Microorganisms

Proc Natl Acad Sci U S A, 2001 Jun 5, 98(12), 6725 - 9 Epub 2001 May 22.
Evidence for clonal propagation in natural isolates of Plasmodium falciparum from Venezuela; Urdaneta L et al.; We have analyzed 75 isolates of Plasmodium falciparum, collected in Venezuela during both the dry (November) and rainy (May-July) seasons, with a range of genetic markers including antigen genes and 14 random amplified polymorphic DNA (RAPD) primers . Thirteen P . falciparum stocks from Kenya and four other Plasmodium species are included in the analysis for comparison . Cross-hybridization shows that the 14 RAPD primers reveal 14 separate regions of the parasite's genome . The P . falciparum isolates are a monophyletic clade, significantly different from the other Plasmodium species . We identify three RAPD characters that could be useful as "tags" for rapid species identification . The Venezuelan genotypes fall into two discrete genetic subdivisions associated with either the dry or the rainy season; the isolates collected in the rainy season exhibit greater genetic diversity . There is significant linkage disequilibrium in each seasonal subsample and in the full sample . In contrast, no linkage disequilibrium is detected in the African sample . These results support the hypothesis that the population structure of P . falciparum in Venezuela, but not in Africa, is predominantly clonal . However, the impact of genetic recombination on Venezuelan P . falciparum seems higher than in parasitic species with long-term clonal evolution like Trypanosoma cruzi, the agent of Chagas' disease . The genetic structure of the Venezuelan samples is similar to that of Escherichia coli, a bacterium that propagates clonally, with occasional genetic recombination.

J Agric Food Chem, 2001 May, 49(5), 2298 - 301
Herbicidal properties of the thaxtomin group of phytotoxins; King RR et al.; The thaxtomins are a group of phytotoxins generated by the bacterium Streptomyces scabies (the main causal organism of potato common scab) . Available members of the group were assessed for herbicidal activity by a variety of standard tests . Test results indicated that thaxtomin A, the predominant member, was also the most physiologically active . Injury symptoms in most instances were similar to those caused by known cellulose biosynthetic inhibitors such as dichlobenil and isoxaben . Although test results indicated that the thaxtomins had many of the biological properties desirable in a commercial herbicide, they nevertheless lacked the systemic phytotoxicity critical to deliver reliable weed control at low rates.

Biometals, 2001 Mar, 14(1), 13 - 22
Influence of divalent cations on the catalytic properties and secondary structure of unadenylylated glutamine synthetase from Azospirillum brasilense; Antonyuk LP et al.; Fully unadenylylated glutamine synthetase (GS) from the endophytic bacterium Azospirillum brasilense Sp245 was isolated and purified . The enzyme was electrophoretically homogeneous and contained strongly bound metal ions, which could not be removed by dialysis . Mn2+, Mg2+, and Co2+ were found to be effective in supporting biosynthetic activity of the A . brasilense GS . Some kinetic properties of Mn2+-activated and Mg2+-activated unadenylylated GS were characterized . Circular dichroism analysis of the enzyme showed that the A . brasilense GS is a highly structured protein: 59% of its residues form alpha-helices and 13% beta-strands . Removal of the metal ions from the A . brasilense GS by treatment with EDTA resulted in alterations in the enzyme secondary structure.

Prehospital Disaster Med, 2001 Jan-Mar, 16(1), 14 - 7
Aseptic efficacy of prefilled syringes in a polluted environment; Ninomiya N et al.; INTRODUCTION: To evaluate the aseptic efficacy of prefilled syringes compared with ampules when used in a polluted environment similar to that at a disaster site . METHODS: The researchers tested epinephrine, 0.1%, atropine sulfate, 0.05%, and lidocaine hydrochloride solutions, 2% (Group A) as well as lidocaine hydrochloride, 10%, sodium bicarbonate, 8.4%, and glucose solutions, 50% (Group B), that frequently are used for intravenous injection and intravenous infusion respectively in Disaster Medicine . Each of these solutions in 10 prefilled syringes (PFSs) and 10 ampules was placed in a box of contaminated soil along with needles and empty syringes for ampules . In the box, each was taken out of its package, all syringes were connected with a needle, and empty syringes were filled with a solution . After this procedure, all syringes were taken out of the box to check their contents for bacterial contamination . RESULTS: No bacterium was observed in any of the 10 PFS samples of Group A and B solutions . In contrast, out of 10 ampule samples, six of the 10 samples containing epinephrine, nine of the 10 containing atropine sulfate, all 10 samples containing lidocaine hydrochloride, 2%, and all of the ampule samples containing Group B solutions tested positive for bacteria . A statistically significant difference was observed between the PFS and ampule samples in all six solutions . CONCLUSION: Results indicate that, in environments with airborne contaminants, the use of prefilled syringes may be useful for preventing bacterial contamination of the medicine inside.

Science, 2001 May 18, 292(5520), 1360 - 3
Bacterial recognition of mineral surfaces: nanoscale interactions between Shewanella and alpha-FeOOH; Lower SK et al.; Force microscopy has been used to quantitatively measure the infinitesimal forces that characterize interactions between Shewanella oneidensis (a dissimilatory metal-reducing bacterium) and goethite (alpha-FeOOH), both commonly found in Earth near-surface environments . Force measurements with subnanonewton resolution were made in real time with living cells under aerobic and anaerobic solutions as a function of the distance, in nanometers, between a cell and the mineral surface . Energy values {in attojoules (10(-18) joules)} derived from these measurements show that the affinity between S . oneidensis and goethite rapidly increases by two to five times under anaerobic conditions in which electron transfer from bacterium to mineral is expected . Specific signatures in the force curves suggest that a 150-kilodalton putative iron reductase is mobilized within the outer membrane of S . oneidensis and specifically interacts with the goethite surface to facilitate the electron transfer process.

Environ Sci Technol, 2001 Jan 1, 35(1), 182 - 91
Ferrographic tracking of bacterial transport in the field at the narrow channel focus area, Oyster, VA; Johnson WP et al.; The first results from an innovative bacterial tracking technique, ferrographic capture, applied to bacterial transport in groundwater are reported in this paper . Ferrographic capture was used to analyze samples during an October 1999 bacterial injection experiment at the Narrow Channel focus area of the South Oyster site, VA . Data obtained using this method showed that the timing of bacterial breakthrough was controlled by physical (hydraulic conductivity) heterogeneity in the vertical dimension as opposed to variation in sedimentsurface or aqueous chemical properties . Ferrographic tracking yielded results that compared well with results from other tracking techniques over a concentration range of 8 orders of magnitude and provided a low detection limit relative to most other bacterial tracking techniques . The low quantitation limit of this method (approximately 20 cells/mL) allowed observation of transport of an adhesion-deficient bacterium over distances greater than 20 m in the fine sand aquifer underlying this site.

Environ Sci Technol, 2001 Jan 1, 35(1), 127 - 32
The influence of sulfide on solid-phase mercury bioavailability for methylation by pure cultures of Desulfobulbus propionicus (1pr3); Benoit JM et al.; To help understand the mechanism and control of Hg uptake in Hg-methylating bacteria, we investigated the effect of sulfide on Hg methylation by pure cultures of the sulfate-reducing bacterium Desulfobulbus propionicus (1pr3) . Our previous research in natural sediments has suggested that Hg methylation occurs most rapidly when sulfide concentrations favor formation of neutral dissolved Hg-S species . In this study, the chemical speciation of Hg in culture media was manipulated by growing D . propionicus across a range of sulfide concentrations, with inorganic Hg (HgI) added in the form of ground ores . A solid-phase, rather than a dissolved source of Hg, was used to simulate the controls on Hg partitioning between solid and aqueous phases found in natural sediments . Methylmercury (MeHg) production by cultures was not related to the absolute solid-phase concentration of Hg in the ores, and it was only weakly related to the dissolved HgI concentration in the medium . However, MeHg production was linearly related to the calculated concentration of the dominant neutral complex in solution, HgS degrees . Furthermore, the diffusive membrane permeability of HgS degrees, as estimated from its octanol-water partitioning coefficient, was found to be sufficient to support MeHg production by cells . The present paper expands on our previous work by providing experimental support of our hypothesis that sulfide influences methylation by affecting the speciation of dissolved HgI and its uptake via passive diffusion.

J Mol Biol, 2001 May 11, 308(4), 765 - 82
Solution structure, backbone dynamics and chitin binding of the anti-fungal protein from Streptomyces tendae TU901; Campos-Olivas R et al.; AFP1 is a recently discovered anti-fungal, chitin-binding protein from Streptomyces tendae Tu901 . Mature AFP1 comprises 86 residues and exhibits limited sequence similarity to the cellulose-binding domains of bacterial cellulases and xylanases . No similarity to the Cys and Gly-rich domains of plant chitin-binding proteins (e.g . agglutinins, lectins, hevein) is observed . AFP1 is the first chitin-binding protein from a bacterium for which anti-fungal activity was shown . Here, we report the three-dimensional solution structure of AFP1, determined by nuclear magnetic resonance spectroscopy . The protein contains two antiparallel beta-sheets (five and four beta-strands each), that pack against each other in a parallel beta-sandwich . This type of architecture is conserved in the functionally related family II of cellulose-binding domains, albeit with different connectivity . A similar fold is also observed in other unrelated proteins (spore coat protein from Myxococcus xanthus, beta-B2 and gamma-B crystallins from Bos taurus, canavalin from Jack bean) . AFP1 is therefore classified as a new member of the betagamma-crystallin superfamily . The dynamics of the protein was characterized by NMR using amide 15N relaxation and solvent exchange data . We demonstrate that the protein exhibits an axially symmetric (oblate-like) rotational diffusion tensor whose principal axis coincides to within 15 degrees with that of the inertial tensor . After completion of the present structure of AFP1, an identical fold was reported for a Streptomyces killer toxin-like protein . Based on sequence comparisons and clustering of conserved residues on the protein surface for different cellulose and chitin-binding proteins, we postulate a putative sugar-binding site for AFP1 . The inability of the protein to bind short chitin fragments suggests that certain particular architectural features of the solid chitin surface are crucial for the interaction .

Infect Immun, 2001 Jun, 69(6), 4055 - 64
Coiled-coil domain of enteropathogenic Escherichia coli type III secreted protein EspD is involved in EspA filament-mediated cell attachment and hemolysis; Daniell SJ et al.; Many animal and plant pathogens use type III secretion systems to secrete key virulence factors, some directly into the host cell cytosol . However, the basis for such protein translocation has yet to be fully elucidated for any type III secretion system . We have previously shown that in enteropathogenic and enterohemorrhagic Escherichia coli the type III secreted protein EspA is assembled into a filamentous organelle that attaches the bacterium to the plasma membrane of the host cell . Formation of EspA filaments is dependent on expression of another type III secreted protein, EspD . The carboxy terminus of EspD, a protein involved in formation of the translocation pore in the host cell membrane, is predicted to adopt a coiled-coil conformation with 99% probability . Here, we demonstrate EspD-EspD protein interaction using the yeast two-hybrid system and column overlays . Nonconservative triple amino acid substitutions of specific EspD carboxy-terminal residues generated an enteropathogenic E . coli mutant that was attenuated in its ability to induce attaching and effacing lesions on HEp-2 cells . Although the mutation had no effect on EspA filament biosynthesis, it also resulted in reduced binding to and reduced hemolysis of red blood cells . These results segregate, for the first time, functional domains of EspD that control EspA filament length from EspD-mediated cell attachment and pore formation.

FEMS Microbiol Rev, 2001 May, 25(3), 309 - 33
The virulence factors of Bordetella pertussis: a matter of control; Smith AM et al.; Bordetella pertussis is the causative agent of whooping cough, a contagious childhood respiratory disease . Increasing public concern over the safety of whole-cell vaccines led to decreased immunisation rates and a subsequent increase in the incidence of the disease . Research into the development of safer, more efficacious, less reactogenic vaccine preparations was concentrated on the production and purification of detoxified B . pertussis virulence factors . These virulence factors include adhesins such as filamentous haemagglutinin, fimbriae and pertactin, which allow B . pertussis to bind to ciliated epithelial cells in the upper respiratory tract . Once attachment is initiated, toxins produced by the bacterium enable colonisation to proceed by interfering with host clearance mechanisms . B . pertussis co-ordinately regulates the expression of virulence factors via the Bordetella virulence gene (bvg) locus, which encodes a response regulator responsible for signal-mediated activation and repression . This strict regulation mechanism allows the bacterium to express different gene subsets in different environmental niches within the host, according to the stage of disease progression.

Eur J Oral Sci, 2001 Apr, 109(2), 109 - 13
Monoclonal antibody against Porphyromonas gingivalis hemagglutinin inhibits hemolytic activity; Hosogi Y et al.; Porphyromonas gingivalis has been implicated as an important pathogen in the development of adult periodontitis . This bacterium possesses hemagglutinating and hemolytic activities to attach and lyse erythrocytes . Hemolysis by this oral pathogen functions to provide heme-containing molecules for growth in the periodontal pocket . We previously constructed a monoclonal antibody using P . gingivalis vesicles as the immunogen, designated as MAb-Pg-vc, which inhibited vesicle-associated hemagglutinating activity . Furthermore, we cloned the gene encoding 130-kDa hemagglutinin (130-kDa HAG) and identified its functional motif for attachment to erythrocytes . Generally, bacterial cell attachment to erythrocytes is an important initial step for expressing hemolysis activity . In the present study, we examined the effect of MAb-Pg-vc on the hemolytic activity of P . gingivalis cells . The MAb-Pg-vc significantly inhibited the hemolytic activity and, further, this inhibitory activity was reduced by the synthetic peptide of the 130-kDa HAG functional motif.

Dtsch Med Wochenschr, 2001 Apr 12, 126(15), 431 - 3
{Mitral valve endocarditis caused by Erysipelothrix rhusiopathiae}; Heidrich JP et al.; HISTORY AND CLINICAL FINDINGS: A 67 year-old country woman was admitted to the hospital because of a four weeks history of continuous catarrh, arthralgia and fever . Recently, she had also developed upper abdominal pain after oral ibuprofen treatment . The clinical examination showed a patient of impaired general condition . The heart and lungs were auscultatory normal and there were no signs of dyspnea, cyanosis or inflammatory skin lesions . EXAMINATIONS: Physical examination of heart and lung, electrocardiography and transthoracic echocardiography were without pathological findings . CLINICAL COURSE: Gastroscopy revealed acute antral gastritis and duodenitis with presence of Helicobacter pylori . Eradication therapy resolved the abdominal symptoms but fever returned after the antibiotic therapy was stopped . The patient developed a severe endocarditis with progressive mitral regurgitation within a few days . Erysipelothrix rhusiopathiae was isolated from blood cultures and identified by conventional and molecular methods . The patient was treated successfully with 3 x 2 g ampicillin daily, applied parenterally for six weeks, and a mitral valve replacement . CONCLUSION: This was an unusual manifestation of systemic Erysipelothrix rhusiopathiae infection . The bacterium Erysipelothrix rhusiopathiae has still to be considered in the diagnosis and treatment of endocarditis in patients with increased risk of exposure (e.g . farmers, butchers and fishermen).

J Mol Evol, 2001 Apr, 52(4), 333 - 41
Horizontal transfer of the photosynthesis gene cluster and operon rearrangement in purple bacteria; Igarashi N et al.; A 37-kb photosynthesis gene cluster was sequenced in a photosynthetic bacterium belonging to the beta subclass of purple bacteria (Proteobacteria), Rubrivivax gelatinosus . The cluster contained 12 bacteriochlorophyll biosynthesis genes (bch), 7 carotenoid biosynthesis genes (crt), structural genes for photosynthetic apparatuses (puf and puh), and some other related genes . The gene arrangement was markedly different from those of other purple photosynthetic bacteria, while two superoperonal structures, crtEF-bchCXYZ-puf and bchFNBHLM-lhaA-puhA, were conserved . Molecular phylogenetic analyses of these photosynthesis genes showed that the photosynthesis gene cluster of Rvi . gelatinosus was originated from those of the species belonging to the alpha subclass of purple bacteria . It was concluded that a horizontal transfer of the photosynthesis gene cluster from an ancestral species belonging to the alpha subclass to that of the beta subclass of purple bacteria had occurred and was followed by rearrangements of the operons in this cluster.

Bioelectrochemistry, 2001 Mar, 53(2), 233 - 41
Effect of D2O and cryosolvents on the redox properties of bacteriochlorophyll dimer and electron transfer processes in Rhodobacter sphaeroides reaction centers; Paschenko VZ et al.; Effects of environmental changes on the reaction pattern of excitation energy trapping and transformation into the "stable" radical pair P+Q(A)-, have been analyzed in isolated reaction centers of the anoxygenic purple bacterium Rhodobacter sphaeroides . The following results were obtained: (a) replacement of exchangeable protons by deuterons significantly retarded the electron transfer steps of primary charge separation, leading to the radical pair P+I- and of the subsequent reoxidation of I- by the quinone acceptor Q(A) but has virtually no effect on the midpoint potential of P/P+ that was found to be 430+/-20 mV; (b) addition of 70% (v/v) glycerol causes a shift of Em by about 30 mV towards higher values whereas the kinetics of the electron transfer reactions remain almost unaffected; (c) in the presence of the cryoprotectant DMSO, a combined effect arises, i.e . a retardation of the electron transfer kinetics comparable to that induced by H/D exchange and simultaneously an upshift of the Em value to 475+/-20 mV, resembling the action of glycerol . These results are discussed within the framework of effects on the midpoint potential due to the dielectric constant of the medium and changes of the charge distribution in the vicinity of the redox groups and the influence of relaxation processes on electron transfer reactions.

Trends Genet, 2001 May, 17(5), 235 - 7
Plagiarized bacterial genes in the human book of life; Ponting CP; The initial analysis of the human genome draft sequence reveals that our 'book of life' is multi-authored . A small but significant proportion of our genes owes their heritage not to antecedent eukaryotes but instead to bacteria . The publicly funded Human Genome Project study indicates that about 0.5% of all human genes were copied into the genome from bacterial sources . Detailed sequence analyses point to these 'horizontal gene transfer' events having occurred relatively recently . So how did the human 'book of life' evolve to be a chimaera, part animal and part bacterium? And what was the probable evolutionary impact of such gene plagiarism?

Biochim Biophys Acta, 2001 Jun 1, 1505(2-3), 209 - 19
Heterologous expression and properties of the gamma-subunit of the Fe-only hydrogenase from Thermotoga maritima; Verhagen MF et al.; Thermotoga maritima is a hyperthermophilic bacterium that contains a complex, heterotrimeric (alpha(beta)gamma) Fe-only hydrogenase . Sequence analysis indicates that the gene encoding the smallest subunit (gamma), hydC, contains a predicted iron-sulfur cluster binding motif . However, characterization of the native gamma-subunit has been hampered by interference from and the inability to separate intact gamma-subunit from the other two subunits (alpha and beta) . To investigate the function and properties of the isolated gamma-subunit, the gene encoding HydG was expressed in Escherichia coli . Two forms of the recombinant protein were obtained with molecular masses of 10 and 18 kDa, respectively . Both contained a single {2Fe-2S} cluster based on metal analysis, EPR and UV-visible spectroscopy . NH2-terminal sequencing revealed that the 10 kDa protein is a truncated form of the intact gamma-subunit and lacks the first 65 amino acid residues . The midpoint potential of the 18 kDa form was -356 mV at pH 7.0 and 25 degrees C, as measured by direct electrochemistry, and was pH dependent with a pK(ox) of 7.5 and a pK(red) of 7.7 . The oxidized, recombinant gamma-subunit was stable at 80 degrees C under anaerobic conditions with a half-life greater than 24 h, as judged by the UV-visible spectrum of the {2Fe-2S} cluster . In the presence of air the protein was less stable and denatured with a half-life of approx . 2.5 h . The recombinant gamma-subunit was electron transfer competent and was efficiently reduced by pyruvate ferredoxin oxidoreductase from Pyrococcus furiosus, with a Km of 5microM and a Vmax of 9 U/mg . In contrast, native T . maritima hydrogenase holoenzyme and its separated alpha-subunit were much less effective electron donors for the gamma-subunit, with a V(max) of 0.01 U/mg and 0.1 U/mg, respectively.

Enferm Infecc Microbiol Clin, 2001 Feb, 19(2), 49 - 52
{Helicobacter pylori infections: antigen detection in stool samples}; Gonzalez-Cuevas A et al.; BACKGROUND: The aim of this study is to evaluate a new diagnostic test to detect Helicobacter pylori antigen in stool samples (HpSA), and compare the results with those obtained by standard techniques (rapid urease test,culture, histological examination of gastric biopsy specimens,13C-urea breath test and serology), in a paediatric population with gastrointestinal symptomatology . PATIENTS AND METHODS: Sixty patients with dyspeptic symptoms (37 females and 23 males;mean age 10.9 years) attending the Gastroenterology Service were included in the study . Exclusion criterium was previous treatment with proton pump inhibitors, bismuth compounds or antibiotics . Rapid urease test, culture and histologic study of gastric biopsies,13C-urea breath test and serology, as well as HpSA, were performed to all patients . RESULTS: Forty seven patients were considered infected by H.pylori on the basis of bacterium isolation and 13C-urea breath test positivity . HpSAwas detected in 45 of the 47 H.pylori positive patients(95.7%) . There were no HpSA false positive . CONCLUSION: Our results show that this new test is highly sensitive (95%) and specific(100%) for detection of H . pylori infection . It has some advantages over other non invasive techniques: it is easy to perform,requires no blood samples and its cost is lower than that of 13C-urea breath test.

Proc Natl Acad Sci U S A, 2001 May 8, 98(10), 5910 - 5 Epub 2001 May 01.
Two enzymes of diacylglyceryl-O-4'-(N,N,N,-trimethyl)homoserine biosynthesis are encoded by btaA and btaB in the purple bacterium Rhodobacter sphaeroides; Klug RM et al.; Betaine lipids are ether-linked, nonphosphorous glycerolipids that resemble the more commonly known phosphatidylcholine in overall structure . Betaine lipids are abundant in many eukaryotes such as nonseed plants, algae, fungi, and amoeba . Some of these organisms are entirely devoid of phosphatidylcholine and, instead, contain a betaine lipid such as diacylglyceryl-O-4'-(N,N,N,-trimethyl)homoserine . Recently, this lipid also was discovered in the photosynthetic purple bacterium Rhodobacter sphaeroides where it seems to replace phosphatidylcholine under phosphate-limiting growth conditions . This discovery provided the opportunity to study the biosynthesis of betaine lipids in a bacterial model system . Mutants of R . sphaeroides deficient in the biosynthesis of the betaine lipid were isolated, and two genes essential for this process, btaA and btaB, were identified . It is proposed that btaA encodes an S-adenosylmethionine:diacylglycerol 3-amino-3-carboxypropyl transferase and btaB an S-adenosylmethionine-dependent N-methyltransferase . Both enzymatic activities can account for all reactions of betaine lipid head group biosynthesis . Because the equivalent reactions have been proposed for different eukaryotes, it seems likely that orthologs of btaA/btaB may be present in other betaine lipid-containing organisms.

J Biol Chem, 2001 Jul 6, 276(27), 24781 - 9 Epub 2001 Apr 30.
Vitreoscilla hemoglobin . Intracellular localization and binding to membranes; Ramandeep et al.; The obligate aerobic bacterium, Vitreoscilla, synthesizes elevated quantities of a homodimeric hemoglobin (VHb) under hypoxic growth conditions . Expression of VHb in heterologous hosts often enhances growth and product formation . A role in facilitating oxygen transfer to the respiratory membranes is one explanation of its cellular function . Immunogold labeling of VHb in both Vitreoscilla and recombinant Escherichia coli bearing the VHb gene clearly indicated that VHb has a cytoplasmic (not periplasmic) localization and is concentrated near the periphery of the cytosolic face of the cell membrane . OmpA signal-peptide VHb fusions were transported into the periplasm in E . coli, but this did not confer any additional growth advantage . The interaction of VHb with respiratory membranes was also studied . The K(d) values for the binding of VHb to Vitreoscilla and E . coli cell membranes were approximately 5-6 microm, a 4-8-fold higher affinity than those of horse myoglobin and hemoglobin for these same membranes . VHb stimulated the ubiquinol-1 oxidase activity of inverted Vitreoscilla membranes by 68% . The inclusion of Vitreoscilla cytochrome bo in proteoliposomes led to 2.4- and 6-fold increases in VHb binding affinity and binding site number, respectively, relative to control liposomes, suggesting a direct interaction between VHb and cytochrome bo.

Biochemistry, 2001 May 8, 40(18), 5573 - 8
A bacteriochlorophyll a antenna complex from purple bacteria absorbing at 963 nm; Permentier HP et al.; A recently isolated species of the photosynthetic purple sulfur bacteria, provisionally called strain 970, was investigated with respect to its antenna function by means of various spectroscopic techniques, including fluorescence and pump-probe absorption difference spectroscopy . The bacterium contains bacteriochlorophyll a and an as yet unidentified carotenoid, perhaps 3,4,3',4'-tetrahydrospirilloxanthin . It has a single antenna complex of the LH1 type, with a Q(y) absorption band situated at the unusually long wavelength of 963 nm at room temperature and 990 nm at 6 K . In contrast to many other species, the reaction center showed two well-separated absorption bands of bacteriopheophytin at 6 K, located at 747 and 762 nm . The primary electron donor showed a bleaching band centered at 925 nm upon photooxidation . Thus, the energy gap between LH1 and the primary electron donor is quite large in this strain: 425 cm(-1) . Nevertheless, trapping occurred with a time constant of 65 +/- 5 ps, similar to the rates observed in other purple bacteria . As in other species, no back-transfer from the reaction center to the antenna was observed . Our results show that strain 970 is a unique subject for the study of antenna and reaction center function and organization.

Biosci Biotechnol Biochem, 2001 Mar, 65(3), 690 - 3
Piezoresponse of the cyo-operon coding for quinol oxidase subunits in a deep-sea piezophilic bacterium, Shewanella violacea; Nakasone K et al.; We have isolated the genes for quinol oxidase from a deep-sea piezophilic bacterium, Shewanella violacea . Analysis of the deduced amino acid sequences of the cyo subunits showed that this oxidase has high similarity to Escherichia coli bo-type quinol oxidase . Northern blot analysis showed that these genes are expressed at a high level when the bacterium is grown at elevated pressure . Upstream in the cyo-operon, a sigma54-binding motif and an octamer sequence unit were found, suggesting that these elements may play a role in regulation of expression of the cyo-operon in response to changes in pressure.

Biosci Biotechnol Biochem, 2001 Mar, 65(3), 666 - 9
Characterization of the gene encoding the beta-lactamase of the psychrophilic marine bacterium Moritella marina strain MP-1; Tanaka M et al.; The beta-lactamase gene (mbla) of the psychrophilic marine bacterium Moritella marina strain MP-1 was identified in a previously isolated genomic DNA fragment and it was expressed in Escherichia coli cells . The mbla gene encoded a protein consisting of 287 amino acid residues . Its predicted amino acid sequence showed approximately 50% identity with that of a number of class A beta-lactamases, especially with that of CARB/PSE type of beta-lactamases (carbenicillinases) . E . coli transformed with the plasmid containing mbla grew on an ampicillin-containing plate at 37 degrees C but not at 42 degrees C, suggesting that the beta-lactamase of this bacterium is heat-labile.

Biochemistry, 2001 Feb 20, 40(7), 2210 - 9
Distinct reactions catalyzed by bacterial and yeast trans-aconitate methyltransferases; Cai H et al.; The trans-aconitate methyltransferase from the bacterium Escherichia coli catalyzes the monomethyl esterification of trans-aconitate and related compounds . Using two-dimensional (1)H/(13)C nuclear magnetic resonance spectroscopy, we show that the methylation is specific to one of the three carboxyl groups and further demonstrate that the product is the 6-methyl ester of trans-aconitate (E-3-carboxy-2-pentenedioate 6-methyl ester) . A similar enzymatic activity is present in the yeast Saccharomyces cerevisiae . Although we find that yeast trans-aconitate methyltransferase also catalyzes the monomethyl esterification of trans-aconitate, we identify that the methylation product of yeast is the 5-methyl ester (E-3-carboxyl-2-pentenedioate 5-methyl ester) . The difference in the reaction catalyzed by the two enzymes may explain why a close homologue of the E . coli methyltransferase gene is not found in the yeast genome and furthermore suggests that these two enzymes may play distinct roles . However, we demonstrate here that the conversion of trans-aconitate to each of these products can mitigate its inhibitory effect on aconitase, a key enzyme of the citric acid cycle, suggesting that these methyltransferases may achieve the same physiological function with distinct chemistries.

Phys Rev Lett, 2001 Apr 30, 86(18), 4167 - 70
Exciton delocalization probed by excitation annihilation in the light-harvesting antenna LH2; Trinkunas G et al.; Singlet-singlet annihilation is used to study exciton delocalization in the light harvesting antenna complex LH2 (B800-B850) from the photosynthetic purple bacterium Rhodobacter sphaeroides . The characteristic femtosecond decay constants of the high intensity isotropic and the low intensity anisotropy kinetics of the B850 ring are related to the hopping time tau(h) and the coherence length N(coh) of the exciton . Our analysis yields N(coh) = 2.8+/-0.4 and tau(h) = 0.27+/-0.05 ps . This approach can be seen as an extension to the concept of the spectroscopic ruler.

Biochemistry, 2001 Feb 27, 40(8), 2387 - 96
Solution structure of the ribosome recycling factor from Aquifex aeolicus; Yoshida T et al.; The solution structure of ribosome recycling factor (RRF) from hyperthermophilic bacterium, Aquifex aeolicus, was determined by heteronuclear multidimensional NMR spectroscopy . Fifteen structures were calculated using restraints derived from NOE, J-coupling, and T1/T2 anisotropies . The resulting structure has an overall L-shaped conformation with two domains and is similar to that of a tRNA molecule . The domain I (corresponding to the anticodon stem of tRNA) is a rigid three alpha-helix bundle . Being slightly different from usual coiled-coil arrangements, each helix of domain I is not twisted but straight and parallel to the main axis . The domain II (corresponding to the portion with the CCA end of tRNA) is an alpha/beta domain with an alpha-helix and two beta-sheets, that has some flexible regions . The backbone atomic root-mean-square deviation (rmsd) values of both domains were 0.7 A when calculated separately, which is smaller than that of the molecule as a whole (1.4 A) . Measurement of 15N-{1H} NOE values show that the residues in the corner of the L-shaped molecule are undergoing fast internal motion . These results indicate that the joint region between two domains contributes to the fluctuation in the orientation of two domains . Thus, it was shown that RRF remains the tRNA mimicry in solution where it functions.

Biochemistry, 2001 Feb 13, 40(6), 1850 - 60
Retardation of proton transfer caused by binding of the transition metal ion to the bacterial reaction center is due to pKa shifts of key protonatable residues; Gerencser L et al.; Transition metal ions bind to the reaction center (RC) protein of the photosynthetic bacterium Rhodobacter sphaeroides and slow the light-induced electron and proton transfer to the secondary quinone, Q(B) . We studied the properties of the metal ion-RC complex by measuring the pH dependence of the dissociation constant and the stoichiometry of proton release upon ligand formation . We investigated the mechanism of inhibition by measuring the stoichiometry and kinetics of flash-induced proton binding, the transfer of (first and second) electrons to Q(B), and the rate of steady-state turnover of the RC in the absence and presence of Cd(2+) and Ni(2+) on a wide pH range . The following results were obtained . (1) The complexation of transition metal ions Cd(2+) and Ni(2+) with the bacterial RC showed strong pH dependence . This observation was explained by different (pH-dependent) states of the metal-ligand cluster: the complex formation was strong when the ligand (Asp and His residues) was deprotonated and was much weaker if the ligand was partly (or fully) protonated . A direct consequence of the model was the pH-dependent proton release upon complexation . (2) The retardation of transfer of electrons and protons to Q(B) was also strongly pH-dependent . The effect was large in the neutral pH range and decreased toward the acidic and alkaline pH values . (3) Steady-state turnover measurements indicated that the rate of the second proton transfer was much less inhibited than that of the first one, which became the rate-limiting step in continuous turnover of the RC . (4) Sodium azide partly recovered the proton transfer rate . The effect is not due to removal of the bound metal ion by azide but probably by formation of a proton-transporting azide network similarly as water molecules may build up proton pathways . (5) We argue that the inhibition comes mainly from pK(a) shifts of key protonatable residues that control the proton transfer along the H-bond network to Q(B) . The electrostatic interaction between the metal ion and these residues may result in acidic pK(a) shifts between 1.5 and 2.0 that account for the observed retardation of the electron and proton transfer.

Biochemistry, 2001 Feb 13, 40(6), 1587 - 95
A refined model of the chlorosomal antennae of the green bacterium Chlorobium tepidum from proton chemical shift constraints obtained with high-field 2-D and 3-D MAS NMR dipolar correlation spectroscopy; van Rossum BJ et al.; Heteronuclear 2-D and 3-D magic-angle spinning NMR dipolar correlation spectroscopy was applied to determine solid-state (1)H shifts for aggregated bacteriochlorophyll c (BChl c) in uniformly (13)C-enriched light harvesting chlorosomes of the green photosynthetic bacterium Chlorobium tepidum . A complete assignment of 29 different observable resonances of the 61 protons of the aggregated BChl c in the intact chlorosomes is obtained . Aggregation shifts relative to monomeric BChl c in solution are detected for protons attached to rings I, II, and III/V and to their side chains . The 2(1)-H(3), 3(2)-H(3), and 3(1)-H resonances are shifted upfield by -2.2, -1, and -3.3 ppm, respectively, relative to monomeric BChl c in solution . Although the resonances are inhomogeneously broadened and reveal considerable global structural heterogeneity, the 5-CH and the 7-Me responses are doubled, which provides evidence for the existence of at least two relatively well-defined structurally different arrangements . Ab initio quantum chemical modeling studies were performed to refine a model for the self-assembled BChl c with two different types of BChl stacks . The BChl in the stacks can adopt either anti- or syn-configuration of the coordinative bond, where anti and syn designate the relative orientation of the Mg-OH bond relative to the direction of the 17-17(1) bond . The analogy between aggregation shifts for BChl c in the chlorosome and for self-assembled chlorophyll a/H(2)O is explored, and a bilayer model for the tubular supra-structure of sheets of BChl c is proposed, from a homology modeling approach.

J Clin Microbiol, 2001 May, 39(5), 1746 - 50
iceA genotypes of Helicobacter pylori strains isolated from Brazilian children and adults; Ashour AA et al.; Data concerning the geographic distribution of iceA alleles are scarce, and information on the association of the gene with the disease is rare and still controversial . Furthermore, no such study has been developed in Brazil, where duodenal ulcer and gastric adenocarcinoma are very common . We investigated, by PCR, the frequency of iceA alleles and cagA status in Helicobacter pylori strains isolated from 142 patients (62 children and 80 adults; 66 female; mean age, 30.0 years; age range, 3 to 78 years) with gastritis, duodenal ulcer, or gastric adenocarcinoma . iceA was identified in bacterium samples obtained from all patients . Eleven (7.7%) of them were infected with multiple strains . Among the patients with nonmixed infection, iceA2 allele was detected in 118 (90.1%) . iceA2 allele was associated with ulcer (P = 0.02) and with carcinoma (P = 0.001) . iceA2 amplicons of 229, 334, or 549 bp were detected, but none of them was associated with the patient's disorder . iceA2 strains were more frequent in patients older than 7 years (P = 0.001) . The gene was also more frequent in strains obtained from males (P = 0.02) . cagA was more common in strains obtained from carcinoma (P = 0.0008) and ulcer patients (P < 0.006) . cagA-positive strains were more frequent in children older than 7 years (P < 0.003) . No association between cagA status and sex was found (P = 0.28) . In conclusion, we think iceA should not be used as a reliable marker for predicting the clinical outcome of H . pylori infection.

J Biol Chem, 2001 Jul 13, 276(28), 25791 - 6 Epub 2001 Apr 26.
Structural determinants of cold adaptation and stability in a large protein; D'Amico S et al.; The heat-labile alpha-amylase from an antarctic bacterium is the largest known protein that unfolds reversibly according to a two-state transition as shown by differential scanning calorimetry . Mutants of this enzyme were produced, carrying additional weak interactions found in thermostable alpha-amylases . It is shown that single amino acid side chain substitutions can significantly modify the melting point T(m), the calorimetric enthalpy Delta H(cal), the cooperativity and reversibility of unfolding, the thermal inactivation rate constant, and the kinetic parameters k(cat) and K(m) . The correlation between thermal inactivation and unfolding reversibility displayed by the mutants also shows that stabilizing interactions increase the frequency of side reactions during refolding, leading to intramolecular mismatches or aggregations typical of large proteins . Although all mutations were located far from the active site, their overall trend is to decrease both k(cat) and K(m) by rigidifying the molecule and to protect mutants against thermal inactivation . The effects of these mutations indicate that the cold-adapted alpha-amylase has lost a large number of weak interactions during evolution to reach the required conformational plasticity for catalysis at low temperatures, thereby producing an enzyme close to the lowest stability allowing maintenance of the native conformation.

J Bacteriol, 2001 May, 183(10), 3204 - 10
A homolog of the CtrA cell cycle regulator is present and essential in Sinorhizobium meliloti; Barnett MJ et al.; During development of the symbiotic soil bacterium Sinorhizobium meliloti into nitrogen-fixing bacteroids, DNA replication and cell division cease and the cells undergo profound metabolic and morphological changes . Regulatory genes controlling the early stages of this process have not been identified . As a first step in the search for regulators of these events, we report the isolation and characterization of a ctrA gene from S . meliloti . We show that the S . meliloti CtrA belongs to the CtrA-like family of response regulators found in several alpha-proteobacteria . In Caulobacter crescentus, CtrA is essential and is a global regulator of multiple cell cycle functions . ctrA is also an essential gene in S . meliloti, and it is expressed similarly to the autoregulated C . crescentus ctrA in that both genes have complex promoter regions which bind phosphorylated CtrA.

J Bacteriol, 2001 May, 183(10), 3169 - 75
Promoter cloning in the radioresistant bacterium Deinococcus radiodurans; Meima R et al.; Deinococcus radiodurans is a highly radiation-resistant bacterium that is classed in a major subbranch of the bacterial domain . Since very little is known about gene expression in this bacterium, an initial study of promoters was undertaken . In order to isolate promoters and study promoter function, a series of integrative vectors for stable chromosomal insertion in D . radiodurans were developed . These vectors are based on Escherichia coli replicons that are unable to replicate autonomously in D . radiodurans and carry homologous sequences for replacement recombination in the D . radiodurans chromosome . The resulting integration vectors were used to study expression of reporter genes fused to a number of putative promoters that were amplified from the D . radiodurans R1 genome . Further analysis of these and other putative promoters was performed by Northern hybridization and primer extension experiments . In contrast to previous reports, the -10 and -35 regions of these promoters resembled the sigma(70) consensus sequence of E . coli.

J Bacteriol, 2001 May, 183(10), 3142 - 8
The N terminus of FliM is essential to promote flagellar rotation in Rhodobacter sphaeroides; Poggio S et al.; FliM is part of the flagellar switch complex . Interaction of this protein with phospho-CheY (CheY-P) through its N terminus constitutes the main information relay point between the chemotactic system and the flagellum . In this work, we evaluated the role of the N terminus of FliM in the swimming behavior of Rhodobacter sphaeroides . Strains expressing the FliM protein with substitutions in residues previously reported in Escherichia coli as being important for interaction with CheY showed an increased stop frequency compared with wild-type cells . In accordance, we observed that R . sphaeroides cells expressing FliM lacking either the first 13 or 20 amino acids from the N terminus showed a stopped phenotype . We show evidence that FliMDelta13 and FliMDelta20 are stable proteins and that cells expressing them allow flagellin export at levels indistinguishable from those detected for the wild-type strain . These results suggest that the N-terminal region of FliM is required to promote swimming in this bacterium . The role of CheY in controlling flagellar rotation in this organism is discussed.

J Bacteriol, 2001 May, 183(10), 3117 - 26
A Phosphopantetheinyl transferase homolog is essential for Photorhabdus luminescens to support growth and reproduction of the entomopathogenic nematode Heterorhabditis bacteriophora; Ciche TA et al.; The bacterium Photorhabdus luminescens is a symbiont of the entomopathogenic nematode Heterorhabditis bacteriophora . The nematode requires the bacterium for infection of insect larvae and as a substrate for growth and reproduction . The nematodes do not grow and reproduce in insect hosts or on artificial media in the absence of viable P . luminescens cells . In an effort to identify bacterial factors that are required for nematode growth and reproduction, transposon-induced mutants of P . luminescens were screened for the loss of the ability to support growth and reproduction of H . bacteriophora nematodes . One mutant, NGR209, consistently failed to support nematode growth and reproduction . This mutant was also defective in the production of siderophore and antibiotic activities . The transposon was inserted into an open reading frame homologous to Escherichia coli EntD, a 4'-phosphopantetheinyl (Ppant) transferase, which is required for the biosynthesis of the catechol siderophore enterobactin . Ppant transferases catalyze the transfer of the Ppant moiety from coenzyme A to a holo-acyl, -aryl, or -peptidyl carrier protein(s) required for the biosynthesis of fatty acids, polyketides, or nonribosomal peptides . Possible roles of a Ppant transferase in the ability of P . luminescens to support nematode growth and reproduction are discussed.

J Med, 2001, 32(1-2), 97 - 112
Different effects of H . pylori water extracts on cytokines, pepsinogen C and gastrin mucosal release in patients with or without duodenal ulcer; Basso D et al.; In the present study we ascertained whether cagA positive and negative H . pylori strains release water soluble products that can influence the production of gastric mucosal cytokines and endocrine (gastrin) or exocrine (pepsinogen C) secretion in 23 H . pylori positive and 19 H . pylori negative patients . Antral biopsies were obtained to classify inflammation, activity, atrophy, intestinal metaplasia and H . pylori density grade . The cagA gene was identified by means of the polymerase chain reaction (PCR) in H . pylori positive colonies after culture of mucosal samples . Three antral biopsies from each patient were incubated with (1.) Water extracts from cagA positive, (2.) Water extracts from cagA negative strains or (3.) H2O (control) at 37 degrees C in a CO2 incubator for 24 hrs . Gastrin, pepsinogen C, IL-1 beta, IL-8, GMCSF, and TNF alpha were measured in the supernatants and mucosal homogenates . H . pylori infection was significantly associated with an increased antral inflammation and activity (chi 2 = 21.7, p < 0.001 and chi 2 = 42.0, p < 0.001), and increased mucosal levels of IL-1 beta, IL-8 and TNF alpha . Water extracts from cagA positive strains enhanced the release of PGC in mucosal biopsy supernatants (p < 0.05) when patients were considered overall and the release of TNF alpha (p < 0.05) when only patients with duodenal ulcer were considered . Water extracts from cagA negative strains stimulated gastrin secretion (p < 0.05) . None of the remaining cytokines were influenced by H . pylori water extracts . In conclusion, pepsinogen C and TNF alpha can be induced by cagA positive water extracts and may contribute to damage the gastric and duodenal mucosa . Our findings indicate that in patients with H . pylori infection the increase of the mucosal levels of IL-1 beta and IL-8 does not depend on H . pylori water soluble products, but probably depends on the entire bacterium.

J Physiol Pharmacol, 2001 Mar, 52(1), 153 - 64
Heat shock protein 70 (HSP70) in gastric adaptation to aspirin in Helicobacter pylori infection; Konturek JW et al.; We have recently shown that adaptation of gastric mucosa to aspirin (ASA) is disturbed in Helicobacter pylori (H . pylori)-infected human stomach, but can be restored by eradication of the bacterium . The aim of this study was 1) to evaluate the influence of H . pylori on expression of heat shock protein 70 (HSP70) during ASA ingestion in these subjects and in mice model and 2) to evaluate, whether altered HSP70 expression might be associated with different adaptation to ASA in H . pylori-positive and eradicated subjects . The gastric mucosal HSP 70 gene expression was determined by quantitative RT-PCR and Western blot and immunohistochemistry during 14 days of ASA ingestion (1 g bid) in the same 8 subjects before and 3 months after successful eradication of H . pylori . In addition, HSP70 mRNA and protein expression were examined in 30 mice without and with H . pylori infection and eradication . During 14 days of ASA treatment, human H . pylori-infected mucosa revealed a decrease of HSP70 expression, while after eradication a higher expression and further increase of HSP70 expression during ASA ingestion were observed . Mice inoculated with H . pylori also exhibited decreased gastric mucosal HSP70 mRNA expression that was restored after eradication therapy . Decreased basal and ASA-induced expression of HSP70 may partly be responsible for impaired gastric adaptation to ASA in H . pylori-positive subjects . We conclude that 1 . The HSP70 gene and protein expression is reduced during infection with H . pylori in men and mice and that gastric adaptation to ASA in H . pylori eradicated subjects is accompanied by increased HSP70 expression; 2 . It is reasonable to assume that decreased HSP70 expression might contribute to disturbed gastric adaptation in H . pylori infection in humans and 3 . The expression of HSP70 plays an important role in the mechanism of gastric adaptation to ASA and that H . pylori infection interferes with this adaptation due to decrease of HSP70 expression in gastric mucosal cells.

Int J Syst Evol Microbiol, 2001 Mar, 51(Pt 2), 679 - 82
Actinomyces catuli sp . nov., from dogs; Hoyles L et al.; An Actinomyces-like bacterium was recovered from two dogs . Based on cellular morphology and biochemical criteria, the unknown bacterium resembled the genus Actinomyces but it did not appear to correspond to any of the currently recognized species of this genus . PAGE analysis of whole-cell proteins confirmed that the strain was phenotypically distinct from all other Actinomyces species and comparative 16S rRNA gene sequencing showed that the bacterium represents an unknown sub-line within the genus . Based on phenotypic and phylogenetic evidence, it is proposed that the bacterium from dogs be classified as a new species of the genus Actinomyces, Actinomyces catuli . The type strain of Actinomyces catuli is CCUG 41709T (= CIP 106507T).

Int J Syst Evol Microbiol, 2001 Mar, 51(Pt 2), 559 - 63
Asaia siamensis sp . nov., an acetic acid bacterium in the alpha-proteobacteria; Katsura K et al.; Five bacterial strains were isolated from tropical flowers collected in Thailand and Indonesia by the enrichment culture approach for acetic acid bacteria . Phylogenetic analysis based on 16S rRNA gene sequences showed that the isolates were located within the cluster of the genus Asaia . The isolates constituted a group separate from Asaia bogorensis on the basis of DNA relatedness values . Their DNA G+C contents were 58.6-59.7 mol%, with a range of 1.1 mol%, which were slightly lower than that of A . bogorensis (59.3-61.0 mol%), the type species of the genus Asaia . The isolates had morphological, physiological and biochemical characteristics similar to A . bogorensis strains, but the isolates did not produce acid from dulcitol . On the basis of the results obtained, the name Asaia siamensis sp . nov . is proposed for these isolates . Strain S60-1T, isolated from a flower of crown flower (dok rak, Calotropis gigantea) collected in Bangkok, Thailand, was designated the type strain ( = NRIC 0323T = JCM 10715T = IFO 16457T).

Pathol Biol (Paris), 2001 Mar, 49(2), 128 - 37
{Contribution of the laboratory to the epidemiologic study of bacterial infections}; Biron M et al.; The laboratory plays a significant role in the epidemiologic investigations by the comparative analysis of the bacterial strains involved in the outbreaks . Recently, the use of molecular analysis methods provided better performance than traditional phenotypic methods which are still used as preliminary tests because of their relatively low cost and technical simplicity . These analyses deal with either the whole chromosome of the bacterium, plasmids or particular genes . The classification of these methods runs up against the lack of consensus concerning their nomenclature . A clearer denomination based upon the technique responsible for revealing the polymorphisms of these various targets, makes it possible to divide these methods in two principal groups: methods of RFLP (based on the fragments resulting from digestion with restriction enzymes) and methods of AFLP (based on the products of amplification by PCR) . The knowledge of the typability of the strains and the qualities of these various methods, particularly their discriminatory power, is essential to the accuracy of the laboratory analysis in the investigations of outbreaks.

BMC Biotechnol . 2001;1(1):1 . Epub 2001 Apr 18.
Inhibition of spontaneous induction of lambdoid prophages in Escherichia coli cultures: simple procedures with possible biotechnological applications; Czyz A et al.; BACKGROUND: Infections of bacterial cultures by bacteriophages are serious problems in biotechnological laboratories . Apart from such infections, prophage induction in the host cells may also be dangerous . Escherichia coli is a commonly used host in biotechnological production, and many laboratory strains of this bacterium harbour lambdoid prophages . These prophages may be induced under certain conditions leading to phage lytic development . This is fatal for further cultivations as relatively low, though still significant, numbers of phages may be overlooked . Thus, subsequent cultures of non-lysogenic strains may be infected and destroyed by such phage . RESULTS: Here we report that slow growth of bacteria decreases deleterious effects of spontaneous lambdoid prophage induction . Moreover, replacement of glucose with glycerol in a medium stimulates lysogenic development of the phage after infection of E . coli cells . A plasmid was constructed overexpressing the phage 434 cI gene, coding for the repressor of phage promoters which are necessary for lytic development . Overproduction of the cI repressor abolished spontaneous induction of the lambda(imm434) prophage . CONCLUSIONS: Simple procedures that alleviate problems with spontaneous induction of lambdoid prophage and subsequent infection of E . coli strains by these phages are described . Low bacterial growth rate, replacement of glucose with glycerol in a medium and overproduction of the cI repressor minimise the risk of prophage induction during cultivation of lysogenic bacteria and subsequent infection of other bacterial strains.

Mikrobiologiia, 2000 Sep-Oct, 69(5), 717 - 21
{Evaluation of the effect of ecologically hazardous pollutants on the bacteriolytic activity of the predatory bacterium Bdellovibrio}; Markelova NIu et al.; We studied the effect of various concentrations of ecologically hazardous pollutants, urea, phenol, diuron, and cadmium ions, on the physiological activity and survival of the parasitic bacterium Bdellovibrio . Experiments showed that the survival of bdellovibrios in the presence of the pollutants was two times higher when they were cultivated on agar than when they were cultivated in liquid medium . The data obtained are in agreement with the recent concept of the surface-associated state as a survival strategy of bdellovibrios in various ecosystems.

Can J Microbiol, 2001 Mar, 47(3), 206 - 12
Regulation of nitrogenase in the photosynthetic bacterium Rhodobacter sphaeroides containing draTG and nifHDK genes from Rhodobacter capsulatus; Yakunin AF et al.; The photosynthetic bacteria Rhodobacter capsulatus and Rhodospirillum rubrum regulate their nitrogenase activity by the reversible ADP-ribosylation of nitrogenase Fe-protein in response to ammonium addition or darkness . This regulation is mediated by two enzymes, dinitrogenase reductase ADP-ribosyl transferase (DRAT) and dinitrogenase reductase activating glycohydrolase (DRAG) . Recently, we demonstrated that another photosynthetic bacterium, Rhodobacter sphaeroides, appears to have no draTG genes, and no evidence of Fe-protein ADP-ribosylation was found in this bacterium under a variety of growth and incubation conditions . Here we show that four different strains of Rba . sphaeroides are incapable of modifying Fe-protein, whereas four out of five Rba . capsulatus strains possess this ability . Introduction of Rba . capsulatus draTG and nifHDK (structural genes for nitrogenase proteins) into Rba . sphaeroides had no effect on in vivo nitrogenase activity and on nitrogenase switch-off by ammonium . However, transfer of draTG from Rba . capsulatus was sufficient to confer on Rba . sphaeroides the ability to reversibly modify the nitrogenase Fe-protein in response to either ammonium addition or darkness . These data suggest that Rba . sphaeroides, which lacks DRAT and DRAG, possesses all the elements necessary for the transduction of signals generated by ammonium or darkness to these proteins.

J Agric Food Chem, 2001 Mar, 49(3), 1200 - 2
Analysis of canthaxanthin and related pigments from Gordonia jacobaea mutants; de Miguel T et al.; A collection of 43 mutant strains of the bacterium Gordonia jacobaea was obtained by means of ethyl methanesulfonate treatment, and the strains were selected for their different pigmentation with respect to the wild-type strain . None of the mutants showed auxotrophy . They all showed good genetic stability and a growth rate similar to that of the parental strain . Canthaxanthin and other carotenoids from these mutants were extracted with acetone and ethanol and separated by high-performance liquid chromatography (HPLC) . These HPLC analyses, together with spectrophotometric detection at 480 nm, revealed variations in the pigment contents of the different mutant strains.

Mol Microbiol, 2001 Apr, 40(2), 387 - 96
Non-heritable change of a spirochaete's phenotype by decoration of the cell surface with exogenous lipoproteins; Bunikis J et al.; Genetic transformation of Borrelia spp . is limited in development and has found application in only one species . For a non-genetic approach for manipulating the phenotype of these spirochaetes, we determined whether exogenous recombinant lipoproteins would incorporate in the cell's outer membrane . Using unlabelled or 125I-labelled Osp proteins, Osp-specific monoclonal antibodies, proteinase K and formaldehyde as reagents, we found that decoration of spirochaetes had the following characteristics . (i) Purified recombinant OspA or OspD lipoproteins associated with Borrelia burgdorferi and B . hermsii cells that lacked abundant lipoproteins of their own . (ii) This decoration of the cells with exogenous OspA did not affect cell's viability . (iii) The decoration was concentration and temperature dependent and stable for at least 24 h . (iv) Like native OspA, the recombinant OspA decorating the cells was accessible to antibodies and proteases and could be cross-linked to the integral outer membrane protein, P66 . (v) Decoration of viable B . burgdorferi and B . hermsii with OspA rendered the cells susceptible to killing by OspA-specific antiserum . Such non-genetic alteration of the surface of a bacterium may be used to study functions and properties of lipoproteins in situ.

Fish Shellfish Immunol, 2001 Feb, 11(2), 143 - 53
Response of haemocyte lysosomes to bacterial inoculation in the oysters Ostrea edulis L . and Crassostrea gigas (Thunberg) and the scallop Pecten maximus (L); Hauton C et al.; Data are presented that demonstrate the application of the neutral red retention assay (NRR) to monitor the effects of a bacterial inoculation on the haemocyte lysosomes of the European flat oyster Ostrea edulis, Pacific oyster Crassostrea gigas and scallop Pecten maximus . Bivalves were acclimated to three temperature regimes (5, 15 and 25 degrees C), at constant salinity for 7 days in the laboratory . Once baseline responses to acclimation temperature had been established, the effects of an in vivo inoculation on haemocyte lysosomal stability were assessed using the NRR assay . Lysosomal membrane stability was reduced in the presence of bacteria for all three species of bivalve, but destabilisation of C . gigas haemocyte lysosomes appeared to be most sensitive to the presence of the bacterium Listonella anguillarum . For all three bivalve species, the reduction in lysosomal stability appeared to be proportional to the growth of the bacterial inoculate . Using appropriate controls, the NRR assay was demonstrated to have great potential as a tool with which to make rapid initial assessments of the immune status of bivalve molluscs.

Scand J Infect Dis, 2001, 33(3), 163 - 74
An update on Helicobacter pylori microbiology and infection for the new millennium; Enroth H et al.; The finding of the bacterium Helicobacter pylori in patients with symptomatic gastric diseases was a breakthrough for both treatment of peptic ulcer disease and studies of other infectious diseases . Helicobacter pylori infection is rare among the young, indicating that improved childhood living conditions have halted the transmission of the bacterium within families, with a parallel decrease in symptomatic gastroduodenal diseases . Extensive strain variation in H . pylori has been demonstrated at both the genomic and the protein level, and the interstrain variation is higher than in any other bacterium studied so far . Pathogenic markers in H . pylori and host genetics are both of importance for disease outcome . Genotypic or phenotypic markers of H . pylori strains may be used to discriminate patients who should undergo eradication therapy from those who might not benefit from it . Possible positive effects of the infection are still under investigation, and several hypotheses regarding the etiology of diseases in different parts of the stomach have been proposed . To be able to separate the disease-causing infections from the silent infections is a real challenge for the new millennium, and one of the most important issues for therapy and prevention, in the research field of H . pylori.

Extremophiles, 2001 Feb, 5(1), 53 - 60
Liposome-mediated DNA uptake and transient expression in Thermotoga; Yu JS et al.; We report here the successful application of a PCR-based method to detect genetic transformation of Thermotoga neapolitana and Thermotoga maritima . Plasmid vectors were constructed using pRQ7, an 846-bp plasmid found in Thermotoga species strain RQ7, which replicates by a rolling circle mechanism . The vector pJY1 was constructed by placing a gene encoding a thermostable chloramphenicol acetyltransferase from Stacphylococcus aureus under the control of the tac promoter and joining this with pRQ7 in a pBluescript vector . A second vector, pJY2, was similarly constructed using a gene encoding a kanamycin nucleotidyltransferase previously engineered for thermostability . Genetic transformation of T . neapolitana and T . maritima spheroplasts was achieved using cationic liposomes . The transforming DNA was detected in cells grown in liquid cultures using polymerase chain reaction amplification of the cat or kan genes . T . neapolitana could maintain pJY1 for at least 25 generations in liquid medium containing chloramphenicol . The pJY2 vector conferred kanamycin resistance to T . maritima cells grown in liquid culture . Isolation of stable transformants on solid media after 2-3 days of incubation at 77 degrees C was not possible with either vector, probably because of the instability of both vectors and antibiotics under these conditions . However, this transformation procedure provides, for the first time, a method to introduce DNA into this hyperthermophilic bacterium for potential applications such as targeted gene disruption analyses.

Tidsskr Nor Laegeforen, 2001 Mar 10, 121(7), 805 - 6
{Human granulocytic ehrlichiosis in Norway}; Kristiansen BE et al.; BACKGROUND: The bacterium that causes human granulocytic ehrlichiosis may be transmitted by ticks . MATERIAL AND METHODS: We describe two patients with human granulocytic ehrlichiosis . During the summer of 1998, both patients were bitten by ticks . Four to 7 days later they developed influenza-like symptoms with fever, headache and myalgia . After 4 and 21 days, respectively, both patients were given doxycycline for suspected bacterial respiratory diseases, and recovered . RESULTS: Blood samples for human granulocytic ehrlichiosis antibodies showed a fourfold increase in titer in one patient and a remaining high titer in the other . Both patients had a positive polymerase chain reaction with primers specific for the Ehrlichia phagocytophilae genogroup . INTERPRETATION: The two patients fulfill the human granulocytic ehrlichiosis diagnostic criteria set by Centers for Disease Controls and Prevention, and are the first two human granulocytic ehrlichiosis cases described in Norway.

Plant Physiol, 2001 Apr, 125(4), 1585 - 90
Expression of bar in the plastid genome confers herbicide resistance; Lutz KA et al.; Phosphinothricin (PPT) is the active component of a family of environmentally safe, nonselective herbicides . Resistance to PPT in transgenic crops has been reported by nuclear expression of a bar transgene encoding phosphinothricin acetyltransferase, a detoxifying enzyme . We report here expression of a bacterial bar gene (b-bar1) in tobacco (Nicotiana tabacum cv Petit Havana) plastids that confers field-level tolerance to Liberty, an herbicide containing PPT . We also describe a second bacterial bar gene (b-bar2) and a codon-optimized synthetic bar (s-bar) gene with significantly elevated levels of expression in plastids (>7% of total soluble cellular protein) . Although these genes are expressed at a high level, direct selection thus far did not yield transplastomic clones, indicating that subcellular localization rather than the absolute amount of the enzyme is critical for direct selection of transgenic clones . The codon-modified s-bar gene is poorly expressed in Escherichia coli, a common enteric bacterium, due to differences in codon use . We propose to use codon usage differences as a precautionary measure to prevent expression of marker genes in the unlikely event of horizontal gene transfer from plastids to bacteria . Localization of the bar gene in the plastid genome is an attractive alternative to incorporation in the nuclear genome since there is no transmission of plastid-encoded genes via pollen.

Mol Microbiol, 2001 Apr, 40(1), 257 - 69
BldD is a direct regulator of key developmental genes in Streptomyces coelicolor A3(2); Elliot MA et al.; BldD is a transcription factor required for aerial hyphae formation in the filamentous bacterium Streptomyces coelicolor . Three targets of BldD regulation were discovered by a number of means, including examination of bld gene interdependence, selective enrichment of chromosomal DNA fragments bound by BldD and searching the promoter regions of known developmental genes for matches to a previously characterized BldD binding site . The three BldD targets identified were the developmental sigma factor genes, whiG and bldN, and a previously uncharacterized gene, designated bdtA, encoding a putative transcription factor . In each target gene, the sequences bound by BldD were characterized by electrophoretic mobility shift and DNase I footprinting assays, and their alignment suggested AGTgA (n)m TCACc as a consensus BldD operator . The in vivo effect of mutation in bldD on the expression of these three target genes was assessed using S1 nuclease protection assays . In each case, target gene expression was upregulated during early colony development in the bldD background, suggesting that, in the wild type, BldD acts to repress premature expression of whiG, bldN and bdtA during vegetative growth.

Biochemistry, 2001 Mar 27, 40(12), 3737 - 47
Excitation trap approach to analyze size and pigment-pigment coupling: reconstitution of LH1 antenna of Rhodobacter sphaeroides with Ni-substituted bacteriochlorophyll; Fiedor L et al.; Replacement of the central Mg in chlorophylls by Ni opens an ultrafast (tens of femtoseconds time range) radiationless de-excitation path, while the principal ground-state absorption and coordination properties of the pigment are retained . A method has been developed for substituting the native bacteriochlorophyll a by Ni-bacteriochlorophyll a ({Ni}-BChl) in the light harvesting antenna of the core complex (LH1) from the purple bacterium, Rhodobacter (Rb.) sphaeroides, to investigate its unit size and excited state properties . The components of the complex have been extracted with an organic solvent from freeze-dried membranes of an LH1-only strain of Rb . sphaeroides and transferred into the micelles of n-octyl-beta-glucopyranoside (OG) . Reconstitution was achieved by solubilization in 3.4% OG, followed by dilution, yielding a complex nearly identical to the native one, in terms of absorption, fluorescence, and circular dichroism spectra as well as energy transfer efficiency from carotenoid to bacteriochlorophyll . By adding increasing amounts of {Ni}-BChl to the reconstitution mixture, a series of LH1 complexes was obtained that contain increasing levels of this efficient excitation trap . In contrast to the nearly unchanged absorption, the presence of {Ni}-BChl in LH1 markedly affects the emission properties . Incorporation of only 3.2 and 20% {Ni}-BChl reduces the emission by 50% and nearly 100%, respectively . The subnanosecond fluorescence kinetics of the complexes were monoexponential, with the lifetime identical to that of the native complex, and its amplitude decreasing in parallel with the steady-state fluorescence yield . Quantitative analysis of the data, based on a Poisson distribution of the modified pigment in the reconstituted complex, suggests that the presence of a single excitation trap per LH1 unit suffices for efficient emission quenching and that this unit contains 20 +/- 1 BChl molecules.

FEMS Microbiol Ecol, 2001 Apr, 35(2), 137 - 144
Biological activity and colonization pattern of the bioluminescence-labeled plant growth-promoting bacterium Kluyvera ascorbata SUD165/26; Ma W et al.; Kluyvera ascorbata SUD165/26 is a spontaneous siderophore-overproducing mutant of K . ascorbata SUD165, which was previously isolated from nickel-contaminated soil and shown to significantly enhance plant growth in soil contaminated with high levels of heavy metals . To develop a better understanding of the functioning of K . ascorbata SUD165/26 in the environment, and to trace its distribution in the rhizosphere, isolates of this bacterium were labeled with either green fluorescent protein or luciferase . When the plant growth-promoting activities of the labeled strains were assayed and compared with the activities of the unlabeled strain, none of the monitored parameters had changed to any significant extent . When the spatial colonization patterns of the labeled bacteria on canola roots were determined after seed application, it was observed that the bacterium was tightly attached to the surface of both roots and seeds, and formed aggregates . The majority of the bacterial population inhabited the upper two thirds of the roots, with no bacteria detected around the root tips.

Vet Microbiol, 2001 May 21, 80(2), 149 - 62
Rapid and accurate typing of Dichelobacter nodosus using PCR amplification and reverse dot-blot hybridisation; Zhou H et al.; Here we describe an approach to genotyping D . nodosus, based on variation in the fimbrial subunit gene (fimA), which uses polymerase chain reaction (PCR) amplification and hybridisation to immobilised oligonucleotides (PCR/oligotyping).The variable region of D . nodosus fimA, amplified and labelled with digoxigenin (DIG) in a single multiplex PCR amplification, was hybridised to a panel of group- and type-specific poly-dT tailed oligonucleotides that were immobilised on a nylon membrane strip . A mixture of positive control poly-dT tailed oligonucleotides was also included on the membrane . After hybridisation the membrane was washed to a defined specificity, and DIG-labelled fragments hybridising were detected with nitroblue tetrazolium (NBT) and 5-bromo-4-chloro-3-indolyl phosphate (SCIP) . The specificity of the oligonucleotides was verified by the lack of cross-reactivity with D . nodosus fimA sequences that had a single base difference . DNA from 14 footrot samples previously genotyped by PCR-SSCP/sequencing {Vet . Microbiol . 71 (2000) 113}, was assayed using the PCR/oligotyping technique . All types of D . nodosus which had been detected previously with a PCR-SSCP/sequencing method were detected by this procedure . However, for three of the 14 footrot samples, PCR/oligotyping detected additional types of D . nodosus . Further PCR amplification using type-specific primers, confirmed that these types of the bacterium were present in the footrot samples . These results indicate that PCR/oligotyping is a specific, accurate, and useful tool for typing footrot samples . In combination with a rapid DNA extraction protocol, D . nodosus strains present in a footrot sample can be accurately identified in less than 2 days.

Epidemiol Infect, 2001 Feb, 126(1), 147 - 52
Presence of Legionellaceae in warm water supplies and typing of strains by polymerase chain reaction; Zietz B et al.; Outbreaks of Legionnaire's disease present a public health challenge especially because fatal outcomes still remain frequent . The aim of this study was to describe the abundance and epidemiology of Legionellaceae in the human-made environment . Water was sampled from hot-water taps in private and public buildings across the area of Gottingen, Germany, including distant suburbs . Following isolation, we used polymerase chain reaction in order to generate strain specific banding profiles of legionella isolates . In total, 70 buildings were examined . Of these 18 (26%) had the bacterium in at least one water sample . Legionella pneumophila serogroups 1, 4, 5 and 6 could be identified in the water samples . Most of the buildings were colonized solely by one distinct strain, as proven by PCR . In three cases equal patterns were found in separate buildings . There were two buildings in this study where isolates with different serogroups were found at the same time.

Epidemiol Infect, 2001 Feb, 126(1), 129 - 33
Survival of Shiga toxin-producing Escherichia coli O157 in marine water and frequent detection of the Shiga toxin gene in marine water samples from an estuary port; Miyagi K et al.; Shiga toxin-producing Escherichia coli (STEC) O157 was investigated with respect to its halotolerance and whether it can survive in marine water . STEC O157 could multiply in a medium containing 5% NaCl and in sterilized marine water, and could survive in unsterilized marine water for at least 15 days . On the basis of these results, we postulated that STEC O157 may survive in natural marine water, and attempted to isolate the bacterium and Shiga toxin gene (stx) from marine water in Japan . The stx, comprising stx1 and stx2, was detected from marine water samples by PCR . STEC and other stx-positive bacteria, however, could not be isolated from these samples in this study . These results indicate that stx-positive bacteria may survive in marine water and suggest the necessity of a survey.

Infect Immun, 2001 May, 69(5), 3502 - 6
Characterization of proteins in the outer membrane preparation of a murine pathogen, Helicobacter bilis; Ge Z et al.; Helicobacter bilis is a bacterial pathogen associated with multifocal hepatitis and inflammatory bowel disease in certain strains of mice . This bacterium colonizes the liver, bile, and lower intestine in mice and has also been isolated from a wide spectrum of laboratory animals . In this study, proteins present in the outer membrane preparation (OMP) of four H . bilis strains isolated from a mouse, a dog, a rat, and a gerbil were characterized and compared with that of Helicobacter pylori, a human gastric pathogen . All four H . bilis strains had similar OMP protein profiles that were distinct from those of H . pylori . Immunoblotting demonstrated that OMP proteins from H . bilis and H . pylori have little cross-reactivity, except for their flagellins . Nine major immunogenic polypeptides were present in the H . bilis OMPs . By using two-dimensional sodium dodecyl sulfate-polyacrylamide gel electrophoresis, five heat-modifiable proteins with molecular masses of 82, 66, 52, 47 and 37 kDa were identified . The N-terminal sequences of the 46- and 47-kDa OMP proteins had no homology with protein sequences available in public databases . These results indicate that H . bilis has a conserved, unique OMP protein profile that is distinct from those of H . pylori.

Infect Immun, 2001 May, 69(5), 3323 - 34
P13, an integral membrane protein of Borrelia burgdorferi, is C-terminally processed and contains surface-exposed domains; Noppa L et al.; To elucidate antigens present on the bacterial surface of Borrelia burgdorferi sensu lato that may be involved in pathogenesis, we characterized a protein, P13, with an apparent molecular mass of 13 kDa . The protein was immunogenic and was expressed in large amounts during in vitro cultivation compared to other known antigens . An immunofluorescence assay, immunoelectron microscopy, and protease sensitivity assays indicated that P13 is surface exposed . The deduced sequence of the P13 peptide revealed a possible signal peptidase type I cleavage site, and computer analysis predicted that P13 is an integral membrane protein with three transmembrane-spanning domains . Mass spectrometry, in vitro translation, and N- and C-terminal amino acid sequencing analyses indicated that P13 was posttranslationally processed at both ends and modified by an unknown mechanism . Furthermore, p13 belongs to a gene family with five additional members in B . burgdorferi sensu stricto . The p13 gene is located on the linear chromosome of the bacterium, in contrast to five paralogous genes, which are located on extrachromosomal plasmids . The size of the p13 transcript was consistent with a monocistronic transcript . This new gene family may be involved in functions that are specific for this spirochete and its pathogenesis.

Rev Sci Tech, 2001 Apr, 20(1), 219 - 51
Mycobacterium leprae and Mycobacterium lepraemurium infections in domestic and wild animals; Rojas-Espinosa O et al.; Mycobacterium leprae, the aetiological agent of leprosy in humans, gives rise to a chronic granulomatous disease that affects primarily the skin and peripheral nerves, and secondarily some internal organs such as the testis and the eye; viscera are seldom involved . Depending on host resistance, leprosy may present as a benign disease (tuberculoid leprosy) or as a malignant disease (lepromatous leprosy), with a spectrum of intermediate stages appearing between the two . Immunity against leprosy depends on the cell-mediated immunity of the host, and this is severely compromised in the malignant (lepromatous) form of leprosy . Although culture of M . leprae has never been achieved in artificial media, the bacterium may be grown in several experimental animals, including the armadillo, non-human primates, and to a certain extent, rodents . Naturally acquired leprosy has been reported in wild nine-banded armadillos (Dasypus novemcinctus) and in three species of non-human primates (chimpanzees {Pan troglodytes}, sooty mangabey monkeys {Cercocebus atys} and cynomolgus macaques {Macaca fascicularis}), thus qualifying leprosy as a zoonosis . Murine leprosy is a leprosy-like disease of rats and mice, caused by Mycobacterium lepraemurium . The disease affects primarily viscera and the skin, and very rarely peripheral nerves . Depending on the host strain, rodent leprosy may also evolve as 'lepromatous' or 'tuberculoid' leprosy, and strains of mouse that develop intermediate forms of the disease may exist . Growth of M . lepraemurium on conventional media for mycobacteria is not successful, but the bacterium has been cultured on an egg yolk-based medium . Naturally acquired murine leprosy has been observed in rats, mice and cats, but not in humans or any other species . Thus, in contrast to human leprosy, murine leprosy is not a zoonosis.

Orv Hetil, 2001 Mar 11, 142(10), 509 - 14
{Determination of cagA, vacA genotypes of Helicobacter pylori with real-time PCR-method}; Ruzsovics A et al.; Presence of cagA gene of Helicobacter pylori (H . pylori) increases proliferation of stomach mucosa and it is an index of raised virulence of the bacteria . The vacA gene of H . pylori induces a serious inflammation of stomach . The purpose of this study was to determine cagA and vacA genotypes of H . pylori using real-time polymerase chain reaction (PCR) method with the double strain DNA-(dsDNA) binding SYBR Green I . dye . Results were compared with those of two immunohistochemical methods . 43 patients' paraffin embedded biopsy tissue samples were examined by histology, epidermal growth factor receptor (EGFR), proliferating cell nuclear antigen (PCNA) immunohistochemistry and melting curve analysis of real-time PCR using LightCycler instrument . Results of histology and real-time PCR from gastric biopsies correlated in 57% of cag acases and in 58% of vac cases . Significant difference was detected between normal and gastritis cases in the presence of cagA gene (p = 0.003) and between normal epithelial and intestinal metaplasia cases in the presence of vacA gene (p = 0.045) by investigation of association of histology and genotype of bacterium . Statistically significant difference (p = 0.02) was found between increased cell proliferation and the presence of gastritis . Significant correlation was found between the presence of cagA gene and EGFR expression in intestinal metaplasia cases (p = 0.0418) . Results underlie the statistics that infection with cagA positive H . pylori strain increases the cell proliferation on the stomach mucosa and raises the chance of development of intestinal metaplasia . Infection with vacA positive H . pylori inhibits the signal-transduction pathway of EGFR, which influences mechanisms of mucosa repair . The role of EGFR and H . pylori infection is yet unclear in intestinal metaplasia and cancer . The authors' method seem to be suitable for determination of genotypes of H . pylori.

Proc Natl Acad Sci U S A, 2001 Apr 10, 98(8), 4681 - 6 Epub 2001 Apr 03.
Proteomic analysis of the bacterial cell cycle; Grunenfelder B et al.; A global approach was used to analyze protein synthesis and stability during the cell cycle of the bacterium Caulobacter crescentus . Approximately one-fourth (979) of the estimated C . crescentus gene products were detected by two-dimensional gel electrophoresis, 144 of which showed differential cell cycle expression patterns . Eighty-one of these proteins were identified by mass spectrometry and were assigned to a wide variety of functional groups . Pattern analysis revealed that coexpression groups were functionally clustered . A total of 48 proteins were rapidly degraded in the course of one cell cycle . More than half of these unstable proteins were also found to be synthesized in a cell cycle-dependent manner, establishing a strong correlation between rapid protein turnover and the periodicity of the bacterial cell cycle . This is, to our knowledge, the first evidence for a global role of proteolysis in bacterial cell cycle control.

Biochemistry, 2001 Apr 10, 40(14), 4253 - 60
X-ray structure analyses of photosynthetic reaction center variants from Rhodobacter sphaeroides: structural changes induced by point mutations at position L209 modulate electron and proton transfer; Kuglstatter A et al.; The structures of the reaction center variants Pro L209 --> Tyr, Pro L209 --> Phe, and Pro L209 --> Glu from the photosynthetic purple bacterium Rhodobacter sphaeroides have been determined by X-ray crystallography to 2.6-2.8 A resolution . These variants were constructed to interrupt a chain of tightly bound water molecules that was assumed to facilitate proton transfer from the cytoplasm to the secondary quinone Q(B) {Baciou, L., and Michel, H . (1995) Biochemistry 34, 7967-7972} . However, the amino acid exchanges Pro L209 --> Tyr and Pro L209 --> Phe do not interrupt the water chain . Both aromatic side chains are oriented away from this water chain and interact with three surrounding polar side chains (Asp L213, Thr L226, and Glu H173) which are displaced by up to 2.6 A . The conformational changes induced by the bulky aromatic rings of Tyr L209 and Phe L209 lead to unexpected displacements of Q(B) compared to the wild-type protein . In the structure of the Pro L209 --> Tyr variant, Q(B) is shifted by approximately 4 A and is now located at a position similar to that reported for the wild-type reaction center after illumination {Stowell, M . H . B., et al . (1997) Science 276, 812-816} . In the Pro L209 --> Phe variant, the electron density map reveals an intermediate Q(B) position between the binding sites of the wild-type protein in the dark and the Pro L209 --> Tyr protein . In the Pro L209 --> Glu reaction center, the carboxylic side chain of Glu L209 is located within the water chain, and the binding site of Q(B) remains unchanged compared to the wild-type structure.

J Biochem Mol Toxicol, 2001, 15(2), 67 - 75
Crystal structure-based studies of cytosolic sulfotransferase; Yoshinari K et al.; Sulfation is a widely observed biological reaction conserved from bacterium to human that plays a key role in various biological processes such as growth, development, and defense against adversities . Deficiencies due to the lack of the ubiquitous sulfate donor 3'-phosphoadenosine-5'-phosphosulfate (PAPS) are lethal in humans . A large group of enzymes called sulfotransferases catalyze the transfer reaction of sulfuryl group of PAPS to the acceptor group of numerous biochemical and xenochemical substrates . Four X-ray crystal structures of sulfotransferases have now been determined: cytosolic estrogen, hydroxysteroid, aryl sulfotransferases, and a sulfotransferase domain of the Golgi-membrane heparan sulfate N-deacetylase/N-sulfotransferase 1 . These have revealed the conserved core structure of the PAPS binding site, a common reaction mechanism, and some information concerning the substrate specificity . These crystal structures introduce a new era of the study of the sulfotransferases .

Microbiology, 2001 Apr, 147(Pt 4), 1045 - 57
Defining the mycoplasma 'cytoskeleton': the protein composition of the Triton X-100 insoluble fraction of the bacterium Mycoplasma pneumoniae determined by 2-D gel electrophoresis and mass spectrometry; Regula JT et al.; After treating Mycoplasma pneumoniae cells with the nonionic detergent Triton X-100, an undefined, structured protein complex remains that is called the 'Triton X-100 insoluble fraction' or 'Triton shell' . By analogy with eukaryotic cells and supported by ultrastructural analyses it is supposed that this fraction contains the components of a bacterial cytoskeleton-like structure . In this study, the composition of the Triton X-100 insoluble fraction was defined by electron microscopic screening for possible structural elements, and by two-dimensional (2-D) gel electrophoresis and MS to identify the proteins present . Silver staining of 2-D gels revealed about 100 protein spots . By staining with colloidal Coomassie blue, about 50 protein spots were visualized, of which 41 were identified by determining the mass and partial sequence of tryptic peptides of individual proteins . The identified proteins belonged to several functional categories, mainly energy metabolism, translation and heat-shock response . In addition, lipoproteins were found and most of the proteins involved in cytadherence that were previously shown to be components of the Triton X-100 insoluble fraction . There were also 11 functionally unassigned proteins . Based on sequence-derived predictions, some of these might be potential candidates for structural components . Quantitatively, the most prevalent proteins were the heat-shock protein DnaK, elongation factor Tu and subunits alpha and beta of the pyruvate dehydrogenase complex (PdhA, PdhB), but definite conclusions regarding the composition of the observed structures can only be drawn after specific proteins are assigned to them, for example by immunocytochemistry.

Microbiology, 2001 Apr, 147(Pt 4), 995 - 1006
Rapid phenotypic change and diversification of a soil bacterium during 1000 generations of experimental evolution; Riley MS et al.; Evolutionary pathways open to even relatively simple organisms, such as bacteria, may lead to complex and unpredictable phenotypic changes, both adaptive and non-adaptive . The evolutionary pathways taken by 18 populations of Ralstonia strain TFD41 while they evolved in defined environments for 1000 generations were examined . Twelve populations evolved in liquid media, while six others evolved on agar surfaces . Phenotypic analyses of these derived populations identified some changes that were consistent across all populations and others that differed among them . The evolved populations all exhibited morphological changes in their cell envelopes, including reductions of the capsule in each population and reduced prostheca-like surface structures in most populations . Mean cell length increased in most populations (in one case by more than fourfold), although a few populations evolved shorter cells . Carbon utilization profiles were variable among the evolved populations, but two distinct patterns were correlated with genetic markers introduced at the outset of the experiment . Fatty acid methyl ester composition was less variable across populations, but distinct patterns were correlated with the two physical environments . All 18 populations evolved greatly increased sensitivity to bile salts, and all but one had increased adhesion to sand; both patterns consistent with changes in the outer envelope . This phenotypic diversity contrasts with the fairly uniform increases in competitive fitness observed in all populations . This diversity may represent a set of equally probable adaptive solutions to the selective environment; it may also arise from the chance fixation of non-adaptive mutations that hitchhiked with a more limited set of beneficial mutations.

J Biol Chem, 2001 Jun 22, 276(25), 22095 - 9 Epub 2001 Mar 29.
Interaction of cytochrome bd with carbon monoxide at low and room temperatures: evidence that only a small fraction of heme b595 reacts with CO; Borisov VB et al.; Azotobacter vinelandii is an obligately aerobic bacterium in which aerotolerant dinitrogen fixation requires cytochrome bd . This oxidase comprises two polypeptide subunits and three hemes, but no copper, and has been studied extensively . However, there remain apparently conflicting reports on the reactivity of the high spin heme b(595) with ligands . Using purified cytochrome bd, we show that absorption changes induced by CO photodissociation from the fully reduced cytochrome bd at low temperatures demonstrate binding of the ligand with heme b(595) . However, the magnitude of these changes corresponds to the reaction with CO of only about 5% of the heme . CO binding with a minor fraction of heme b(595) is also revealed at room temperature by time-resolved studies of CO recombination . The data resolve the apparent discrepancies between conclusions drawn from room and low temperature spectroscopic studies of the CO reaction with cytochrome bd . The results are consistent with the proposal that hemes b(595) and d form a diheme oxygen-reducing center with a binding capacity for a single exogenous ligand molecule that partitions between the hemes d and b(595) in accordance with their intrinsic affinities for the ligand . In this model, the affinity of heme b(595) for CO is about 20-fold lower than that of heme d.

Appl Environ Microbiol, 2001 Apr, 67(4), 1783 - 7
Purification, characterization, and gene cloning of purine nucleosidase from Ochrobactrum anthropi; Ogawa J et al.; A bacterium, Ochrobactrum anthropi, produced a large amount of a nucleosidase when cultivated with purine nucleosides . The nucleosidase was purified to homogeneity . The enzyme has a molecular weight of about 170,000 and consists of four identical subunits . It specifically catalyzes the irreversible N-riboside hydrolysis of purine nucleosides, the K(m) values being 11.8 to 56.3 microM . The optimal activity temperature and pH were 50 degrees C and pH 4.5 to 6.5, respectively . Pyrimidine nucleosides, purine and pyrimidine nucleotides, NAD, NADP, and nicotinamide mononucleotide are not hydrolyzed by the enzyme . The purine nucleoside hydrolyzing activity of the enzyme was inhibited (mixed inhibition) by pyrimidine nucleosides, with K(i) and K(i)' values of 0.455 to 11.2 microM . Metal ion chelators inhibited activity, and the addition of Zn(2+) or Co(2+) restored activity . A 1.5-kb DNA fragment, which contains the open reading frame encoding the nucleosidase, was cloned, sequenced, and expressed in Escherichia coli . The deduced 363-amino-acid sequence including a 22-residue leader peptide is in agreement with the enzyme molecular mass and the amino acid sequences of NH(2)-terminal and internal peptides, and the enzyme is homologous to known nucleosidases from protozoan parasites . The amino acid residues forming the catalytic site and involved in binding with metal ions are well conserved in these nucleosidases.

J Biol Chem, 2001 Jun 1, 276(22), 18984 - 91 Epub 2001 Mar 16.
Activation of human prothrombin by arginine-specific cysteine proteinases (Gingipains R) from porphyromonas gingivalis; Imamura T et al.; The effect of 95- (HRgpA) and 50-kDa gingipain R (RgpB), arginine-specific cysteine proteinases from periodontopathogenic bacterium Porphyromonas gingivalis on human prothrombin activation was investigated . Each enzyme released thrombin from prothrombin in a dose- and time-dependent manner with the former enzyme, containing adhesion domains, being 17-fold more efficient than the single chain RgpB . A close correlation between the generation of fibrinogen clotting activity and amidolytic activity indicated that alpha-thrombin was produced by gingipains R, and this was confirmed by SDS-polyacrylamide gel electrophoresis, thrombin active site labeling, and amino-terminal sequence analysis of prothrombin digestion fragments . Significantly, the catalytic efficiency of HRgpA to generate thrombin (k(cat)/K(m) = 1.2 x 10(6) m(-)1 s(-)1) was 100-fold higher than that of RgpB (k(cat)/K(m) = 1.2 x 10(4) m(-)1 s(-)1) . The superior prothrombinase activity of HRgpA over RgpB correlates with the fact that only the former enzyme was able to clot plasma, and kinetic data indicate that prothrombin activation can occur in vivo . At P . gingivalis-infected periodontitis sites HRgpA may be involved in the direct production of thrombin and, therefore, in the generation of prostaglandins and interleukin-1, both have been found to be associated with the development and progression of the disease . Furthermore, by taking into account that the P . gingivalis bacterium has been immunolocalized in carotid atherosclerotic plaques at thrombus formation sites (Chiu, B . (1999) Am . Heart J . 138, S534-S536), our results indicate that bacterial proteinases may potentially participate in the pathogenesis of cardiovascular disease associated with periodontitis.

J Mol Biol, 2001 Mar 30, 307(3), 951 - 63
Target recognition by EcoKI: the recognition domain is robust and restriction-deficiency commonly results from the proteolytic control of enzyme activity; O'Neill M et al.; We report a genetic and biochemical analysis of a target recognition domain (TRD) of EcoKI, a type I restriction and modification enzyme . The TRDs of type I R-M systems are within the specificity subunit (HsdS) and HsdS confers sequence specificity to a complex endowed with both restriction and modification activities . Random mutagenesis has revealed that most substitutions within the amino TRD of EcoKI, a region comprising 157 amino acid residues, have no detectable effect on the phenotype of the bacterium, even when the substitutions are non- conservative . The structure of the TRD appears to be robust . All but one of the six substitutions that confer a restriction-deficient, modification-deficient (r(-)m(-)) phenotype were found to be in the interval between residues 80 and 110, a region predicted by sequence comparisons to form part of the protein-DNA interface . Additional site-directed mutations affecting this interval commonly impair both restriction and modification . However, we show that an r(-) phenotype cannot be taken as evidence that the EcoKI complex lacks endonuclease activity; in response to even a slightly impaired modification efficiency, the endonuclease activity of EcoKI is destroyed by a process dependent upon the ClpXP protease.Enzymes from mutants with an r(-)m(-) phenotype commonly retain some sequence-specific activity; methylase activity can be detected on hemimethylated DNA substrates and residual endonuclease activity is implied whenever the viability of the r(-)m(-) bacterium is dependent on ClpXP . Conversely, the viability of ClpX(-) r(-)m(-) bacteria can be used as evidence for little, or no, endonuclease activity . Of 14 mutants with an r(-)m(-) phenotype, only six are viable in the absence of ClpXP . The significance of four of the six residues (G91, G105, F107 and G141) is enhanced by the finding that even conservative substitutions for these residues impair modification, thereby conferring an r(-)m(-) phenotype .

Biosci Biotechnol Biochem, 2001 Jan, 65(1), 63 - 71
Purification and some properties of ubiquinol oxidase from obligately chemolithotrophic iron-oxidizing bacterium, Thiobacillus ferrooxidans NASF-1; Kamimura K et al.; Ubiquinol-oxidizing activity was detected in an acidophilic chemolithotrophic iron-oxidizing bacterium, T . ferrooxidans . The ubiquinol oxidase was purified 79-fold from plasma membranes of T . ferrooxidans NASF-1 cells . The purified oxidase is composed of two polypeptides with apparent molecular masses of 32,600 and 50,100 Da, as measured by gel electrophoresis in the presence of sodium dodecyl sulfate . The absorption spectrum of the reduced enzyme at room temperature showed big peaks at 530 and 563, and a small broad peak at 635 nm, indicating the involvement of cytochromes b and d . Characteristic peaks of cytochromes a and c were not observed in the spectrum at around 600 and 550 nm, respectively . This enzyme combined with CO, and its CO-reduced minus reduced difference spectrum showed peaks at 409 nm and 563 nm and a trough at 431 nm . These results indicated that the oxidase contained cytochrome b, but the involvement of cytochrome d was not clear . The enzyme catalyzed the oxidations of ubiquinol-2 and reduced N,N,N',N'-tetramethyl-p-phenylenediamine dihydrochloride . The ubiquinol oxidase activity was activated by the addition of albumin and lecithin to the reaction mixture and inhibited by the respiratory inhibitors KCN, HQNO, NaN3, and antimycin A1, although the enzyme was relatively resistant to KCN, and the divalent cation, Zn2+, compared with ubiquinol oxidases of E . coli.

Biosci Biotechnol Biochem, 2001 Jan, 65(1), 133 - 42
Purification and characterization of bifunctional alginate lyase from Alteromonas sp . strain no . 272 and its action on saturated oligomeric substrates; Iwamoto Y et al.; A marine bacterium (strain No . 272) isolated from sea mud in Omura Bay produced an alginate lyase and was classified as an Alteromonas species . The enzyme was purified from the culture medium of the bacterium by DEAE-Cellulofine, Sephadex G-100 gel chromatography to an electrophoretically homogeneous state in the presence and absence of SDS . The molecular mass of the enzyme was 23 and 33.9 kDa on Sephadex G-100 column chromatography and SDS-polyacrylamide gel electrophoresis, respectively, with an isoelectric point of 3.8 . The predominant secondary structure of the enzyme was found to be most likely beta-structure by circular dichroism . The enzyme was most active at pH 7.5-8.0 and stable around pH 5-11 . The enzyme was more labile in Tris-HCI buffer (pH 7.0) to heat treatment, than in phosphate buffer (pH 7.0) . No of metal ions significantly affected the enzyme activity . The enzyme acted on sodium alginate in an endo-type manner and on two components of alginate, poly-alpha1,4-L-guluronate and poly-beta1,4-D-mannuronate, as judged by routine ultraviolet assay (235 nm) and circular dichroic spectral changes of the substrates . However, the coexisting poly-alpha1,4-L-guluronate and poly-beta1,4-D-mannuronate apparently interacted with the enzyme in a competitive manner . Although the enzyme depolymerized alginate in an endo-type, it did not act on trimeric guluronate and mannuronate, but on the tetramers or more . The kinetic analyses showed that kcat/Km for each oligomer was larger for the guluronate oligomers than for the mannuronate ones, and that the subsite structure of the enzyme most likely consisted of six binding sites from the intrinsic reaction rate constant (kint) and intrinsic substrate binding constant (Kint).

Electrophoresis, 2000 Nov, 21(17), 3833 - 42
Proteome analysis demonstrates complex replicon and luteolin interactions in pSyma-cured derivatives of Sinorhizobium meliloti strain 2011; Chen H et al.; Sinorhizobium meliloti was studied by proteomic analysis to investigate the contribution made by plasmid-encoded functions on the intracellular regulation of this bacterium . Protein profiles of strain 2011 were compared with those from its mutant strains which were either cured of their pRme2011a (also called pSyma) plasmid (strain 818), or contained an extensive deletion of this plasmid (strain SmA146) . Plasmid pSyma contains the nodulation and nitrogen fixation genes and is 1.4 Mbp with an estimated coding potential of 1,400 proteins . However, under the growth conditions used we could detect 60 differences between the parent strain and its pSyma-cured derivative, strain 818 . While the majority of these differences were due to regulatory changes, such as up- and downregulation, some proteins were totally missing in some strains . These 60 proteins were classified into 21 subgroups, A to U, based on their measured protein levels when the cells were grown in the presence or absence of luteolin . Comparisons were made between the different strains to assess the possible interactions of the different proteins of the subgroups and plasmid pSyma . These results suggest that pSyma has a role in the regulation of the expression of genes from the other replicons (3.5 Mbp chromosome and the 1.7 Mbp pSymB plasmid) present in the S . meliloti cells . Proteome analysis provides a sensitive tool to examine the functional organisation of the S . meliloti genome and the intracellular gene interactions between replicons and will provide a powerful analytical tool to complement the genome sequencing of strain 1021.

Electrophoresis, 2000 Nov, 21(17), 3765 - 80
Towards a two-dimensional proteome map of Mycoplasma pneumoniae; Regula JT et al.; A Proteome map of the bacterium Mycoplasma pneumoniae was constructed using two-dimensional (2-D) gel electrophoresis in combination with mass spectrometry (MS) . M . pneumoniae is a human pathogen with a known genome sequence of 816 kbp coding for only 688 open reading frames, and is therefore an ideal model system to explore the scope and limits of the current technology . The soluble protein content of this bacterium grown under standard laboratory conditions was separated by 1-D or 2-D gel electrophoresis applying various pH gradients, different acrylamide concentrations and buffer systems . Proteins were identified using liquid chromatography-electrospray ionization ion trap and matrix-assisted laser desorption/ionization-MS . Mass spectrometric protein identification was supported and controlled using N-terminal sequencing and immunological methods . So far, proteins from about 350 spots were characterized with MS by determining the molecular weights and partial sequences of their tryptic peptides . Comparing these experimental data with the DNA sequence-derived predictions it was possible to assign these 350 proteins to 224 genes . The importance of proteomics for genome analysis was shown by the identification of four proteins, not annotated in the original publication . Although the proteome map is still incomplete, it is already a useful reference for comparative analyses of M . pneumoniae cells grown under modified conditions.

Electrophoresis, 2000 Nov, 21(17), 3740 - 56
Towards the proteome of Mycobacterium tuberculosis; Rosenkrands I et al.; Human tuberculosis is caused by the intracellular pathogen Mycobacterium tuberculosis . Sequencing of the genome of M . tuberculosis strain H37Rv has predicted 3924 open reading frames, and enabled identification of proteins from this bacterium by peptide mass fingerprinting . Extracellular proteins from the culture medium and proteins in cellular extracts were examined by two-dimensional gel electrophoresis using immobilized pH gradient technology . By mass spectrometry and immunodetection, 49 culture filtrate proteins and 118 lysate proteins were identified, 83 of which were novel . To date, 288 proteins have been identified in M . tuberculosis proteome studies, and a list is presented which includes all identified proteins (available at The information obtained from the M . tuberculosis proteome so far is discussed in relation to the information obtained from the complete genome sequence.

Carbohydr Res, 2001 Feb 15, 330(3), 325 - 33
Structure and conformation of a novel genetically engineered polysaccharide P2; Colquhoun IJ et al.; A new exocellular polysaccharide (P2) has been produced by the manipulation of a glycosyl transferase gene (aceP) involved in the biosynthesis of the polysaccharide acetan by the bacterium Acetobacter xylinum strain CKE5 . The P2 polysaccharide has been studied by methylation analysis, reductive cleavage, and 1H and 13C NMR spectroscopy . The data are consistent with the structure predicted when the aceP gene is deactivated: {Molecular structure: see text} . The effect of cooling on proton NMR line width indicates a coil-helix transition in P2 at about 70 degrees C.

Dig Dis Sci, 2001 Jan, 46(1), 46 - 53
Effect of Helicobacter pylori infection on gastric emptying and gastrointestinal hormones in dyspeptic and healthy subjects; Chiloiro M et al.; There is no general agreement as regards the effect of Helicobacter pylori infection on gastric emptying in patients with functional dyspepsia . Food releases several gastrointestinal hormones, and some of these are known to contribute to the regulation of gastric emptying . The aim of this study was to investigate the influence of H . pylori on gastric emptying in dyspeptic and healthy subjects and to verify whether different hormone secretion patterns are affected by the presence of the bacterium . Twenty-seven patients affected by functional dyspepsia and 30 asymptomatic healthy subjects entered the study . H . pylori presence was assessed in controls by IgG antibodies to H . pylori and {13C} urea breath test, and that in patients by Warthin-Starry stain on gastric biopsies . After ingesting a standard solid-liquid meal, an ultrasound examination of gastric emptying was performed . Plasma concentrations of gastrin, cholecystokinin, and pancreatic polypeptide were measured in the fasting and postprandial period for 4 hours . The incidence of H . pylori infection was not higher in functional dyspepsia patients than in controls . As regards gastric emptying, no difference was detected between patients and controls with and without H . pylori infection . On the contrary, the presence of H . pylori infection determined alterations in gastrin levels, which were higher in controls than in patients . Basal CCK levels were higher in the H . pylori-negative patients than H . pylori-positive patients and controls . In conclusion, H . pylori infection seems not to cause alterations in gastric emptying, but rather alterations in gastrin levels . In contrast, the altered levels of CCK account for its involvement in the pathophysiology of H . pylori-negative dyspepsia.

Curr Microbiol, 2001 Mar, 42(3), 151 - 4
Adhesion of the dissimilatory Fe(III)-reducing bacterium Shewanella alga BrY to crystalline Fe(III) oxides; Das A et al.; Shewanella alga BrY adhesion to hydrous ferric oxide, goethite, and hematite was examined . Adhesion to each oxide followed the Langmuir adsorption model . No correlation between adhesion and Fe(III) oxide surface area or crystallinity was observed . Zeta potential measurements suggested that electrostatic interactions do not influence S . alga BrY adhesion to these minerals . Cell adhesion does not appear to explain the recalcitrance of crystalline Fe(III) oxides to bacterial reduction.

Hepatogastroenterology, 2001 Jan-Feb, 48(37), 104 - 6
Synchronous gastric adenocarcinoma and MALT lymphoma in a patient with H . pylori infection . Could the two neoplasms share a common pathogenesis?
Cammarota G, Larocca LM, D'Ugo D, Persiani R, Cianci R, Nocente R, Picciocchi A, Gasbarrini G.
Low-grade primary MALT (mucosa-associated lymphoid tissue) lymphoma of the stomach is a neoplasm with an indolent course and a good prognosis . Patients with this type of neoplasm seem to have a higher risk for other neoplasms . Of interest is the association of gastric MALT lymphoma with gastric adenocarcinoma of intestinal type . We report the case of a patient, with a history of H . pylori-related gastritis, in whom a diagnosis of synchronous gastric adenocarcinoma of intestinal type and low-grade MALT lymphoma, occurring as collision tumors, was made . The stage procedures confirmed the presence of a locally advanced gastric tumor staged as T3 N1 . The patient underwent two cycles of neoadjuvant EEP (etoposide, epirubicin, cisplatin) chemotherapy . After 2 months, a R0 total gastrectomy with D2-lymphoadenectomy was successfully performed . The development of simultaneous primary gastric lymphoma and carcinoma is a rare event . The possible coexistence of both tumors should be kept in mind, especially in patients infected with H . pylori, since a possible etiopathogenetic role of this bacterium has been differently postulated for both disease.

J Med Entomol, 2001 Jan, 38(1), 99 - 107
Contrasts in tick innate immune responses to Borrelia burgdorferi challenge: immunotolerance in Ixodes scapularis versus immunocompetence in Dermacentor variabilis (Acari: Ixodidae); Johns R et al.; The blacklegged tick, Ixodes scapularis Say, transmits the Lyme disease spirochete Borrelia burgdorferi, whereas the American dog tick, Dermacentor variabilis (Say), is unable to transmit the bacterium . We compared the innate immune response of these ticks against spirochetes directly inoculated into the hemocoel cavity of ticks . In I . scapularis, some Borrelia were found associated with hemocytes, while numerous other spiral-shaped, intact bacteria remained free in the hemolymph . In contrast, in D . variabilis only remnants of the bacteria were evident in the hemolymph, indicating lysis; intact spirochetes were rare . Spirochetes were observed bound to or within the organs of both tick species, although many more spirochetes were found associated with the I . scapularis organs . The few spirochetes observed with the D . variabilis organs appeared to be dead because D . variabilis tissues rarely contained culturable bacteria, unlike I . scapularis tissues . When spirochetes were incubated with I . scapularis hemolymph plasma in vitro, bacterial survival and motility were not reduced . In contrast, incubation of spirochetes with D . variabilis hemolymph plasma resulted in > 50% of the spirochetes becoming nonmotile by 45 min . The differences in the responses of the two different tick species indicate that I . scapularis is immunotolerant when challenged with B . burgdorferi and dependent on a slow phagocytic response to clear Borrelia from the hemolymph . In contrast, D . variabilis is highly immunocompetent (i.e., innate immunity), using plasma borreliacidal factors and a rapid increase in phagocytic cells to clear the infection and limit tissue invasion.

Methods Cell Sci, 2000, 22(2-3), 133 - 6
A method for establishing primary cultures of human gastric epithelial cells; Smoot DT et al.; Long-term culture of human gastric epithelial cells has been difficult, and at present no normal human gastric epithelial cell lines are readily available . As part of our experiments to study pathogenesis of H . pylori, a bacterium that infects the stomach, we developed methods to culture normal human gastric epithelial cells . Primary cultures of human gastric epithelial cells can be established from gastric biopsies taken at upper G.I . endoscopy . Enzymatically isolated gastric epithelial-like cells are present in tight colonies on culture dishes within 24 hours of placing the cells in culture . Cells isolated stain positively for cytokeratin and produce neutral mucins, indicating that they are mucin secreting epithelial cells, consistent with gastric epithelial cells . Epithelial cells can be maintained up to 4 weeks in culture with evidence of DNA synthesis up through the first week of culture.

J Infect Dis, 2001 Apr 15, 183(8), 1229 - 37 Epub 2001 Mar 26.
Localization of Tropheryma whippelii rRNA in tissues from patients with Whipple's disease; Fredricks DN et al.; Whipple's disease is caused by a cultivation-resistant bacterium, Tropheryma whippelii . Ultrastructural studies of intestinal biopsy specimens from patients with Whipple's disease have shown that intracellular and extracellular bacteria are present, but the preferred site of growth is unknown . Tissue sections from 8 patients with Whipple's disease and from 19 healthy control subjects were analyzed by use of fluorescence in situ hybridization and laser scanning confocal microscopy, to determine the location of rRNA that would indicate the presence of metabolically active bacteria . T . whippelii rRNA was most prevalent near the tips of intestinal villi, in the lamina propria, just basal to epithelial cells . Most of the bacterial rRNA signal appeared to be located between cells and did not colocalize with the human intracellular protein vimentin . The location of bacterial rRNA in tissues from patients with Whipple's disease provides evidence that bacteria are growing outside cells and suggests that T . whippelii is not an obligate intracellular pathogen.

Biochemistry, 2001 Mar 6, 40(9), 2894 - 900
Alkaline denaturation of the light-harvesting complex II from the purple bacterium Ectothiorhodospira sp.: kinetic evidence of the existence of the 780 nm upper exciton component of the B850 bacteriochlorophylls; Buche A et al.; The light-harvesting complex II of the purple bacteria has two strong near-infrared electronic absorption bands around 800 (B800) and 850 (B850) nm, arising from the Q(y)() transitions of the bacteriochlorophyll a . In the present work, high concentrations of NaOH were used to study the destabilization of the complex of the Ectothiorhodospira sp . The majority of the bacteriochlorophylls were monomerized within 90 min of treatment . However, the kinetic patterns of the two near-infrared bands were remarkably different . After an instantaneous blue shift from 853 to 828 nm, B850 showed a first-order monomerization with a rate constant of -0.016 min(-1) . This instantaneous blue shift was previously attributed to the deprotonation of a lysine and was independent of the monomerization process . The observed native B800 is in fact composed of two bands, one at 796 nm and the other at 780 nm . The band absorbing at 780 nm red shifted also instantaneously to 786-788 nm and then disappeared in a first-order process as B850 . The other band absorbing at 796 nm has a two-step process of monomerization; after a rapid conversion a slower first-order process occurred with a rate constant of -0.025 min(-1) . The similarity between the kinetic behaviors of B850 and the 780 nm band indicated a strong relationship between these two bands . Our interpretation of the results considers the 780 nm band as the upper exciton component of the B850 bacteriochlorophylls.

Nature, 2001 Mar 8, 410(6825), 268 - 76
Exploring complex networks; Strogatz SH; The study of networks pervades all of science, from neurobiology to statistical physics . The most basic issues are structural: how does one characterize the wiring diagram of a food web or the Internet or the metabolic network of the bacterium Escherichia coli? Are there any unifying principles underlying their topology? From the perspective of nonlinear dynamics, we would also like to understand how an enormous network of interacting dynamical systems-be they neurons, power stations or lasers-will behave collectively, given their individual dynamics and coupling architecture . Researchers are only now beginning to unravel the structure and dynamics of complex networks.

Comp Biochem Physiol C Toxicol Pharmacol, 2001 Mar, 128(3), 359 - 66
Studies on the anti-mitogenic, anti-phage and hypotensive effects of several ribosome inactivating proteins; Wang HX et al.; An investigation was conducted to compare the anti-mitogenic, anti-phage and hypotensive activities of several ribosome inactivating proteins (RIPs) in order to ascertain whether the RIPs differed in their potencies in the various bioassays . Agrostin, luffin and saporin elicited a dose-dependent suppression of the mitogenic response of murine splenocytes to concanavalin A . The three RIPs were approximately equipotent in this regard, with near maximal inhibition attained at a dose of 83 nM and approximately 50% inhibition at 830 pM . Trichosanthin was slightly more potent than the three aforementioned RIPs . All of these RIPs were capable of inhibiting the replication of phage M13 in the bacterium Escherichia coli, the ranking of potencies being luffin>trichosanthin>agrostin when tested at a concentration of 3.5 microM . The RIPs gelonin and saporin did not exert a conspicuous antiviral effect at the same dose . After intravenous administration into normotensive rats via the external jugular vein, the RIPs saporin, trichosanthin, gelonin and momordin evoked a mild hypotensive response while luffin and agrostin were inactive . The hypotensive response, however, lacked dose dependence . The RIPs trichosanthin, momordin and gelonin did not affect the blood pressure response to angiotensin I . Chemical modification of the arginine residues of the RIPs brought about a reduction in their ability to inhibit cell-free translation . It appears that the ranking of potency of RIPs in one bioassay was different from the rankings in other assays.

Infect Immun, 2001 Apr, 69(4), 2383 - 9
Expression of Chlamydia pneumoniae polymorphic membrane protein family genes; Grimwood J et al.; The genome of the obligate intracellular bacterium Chlamydia pneumoniae CWL029 encodes a family of 21 proteins with predicted outer membrane localization . These polymorphic membrane proteins (Pmps) are heterogeneous in both amino acid sequence and predicted size but are unified by the conserved amino acid motifs GGAI and FXXN repeated in the N-terminal half of each protein . Reverse transcriptase PCR analysis showed that all pmp genes are transcribed . To determine whether all proteins are expressed, specific antisera were generated by immunization with mutually exclusive synthetic peptides representing each of the 21 predicted Pmps . Each antiserum reacted with, and was typically immunospecific for, the corresponding peptide immunogen by enzyme-linked immunosorbent assay . Western blot analyses of purified elementary bodies showed that 11 of the 21 Pmps were detectable . Attempts to demonstrate by Sarykosyl fractionation that the Pmps were localized to the outer membrane revealed that several of the Pmps were unstable and readily degraded . Analyses of additional C . pneumoniae strains showed that although some Pmps are conserved, others vary between strains, in both molecular weight and level of expression.

Infect Immun, 2001 Apr, 69(4), 2345 - 52
Interleukin-10 stimulates Coxiella burnetii replication in human monocytes through tumor necrosis factor down-modulation: role in microbicidal defect of Q fever; Ghigo E et al.; Coxiella burnetii, an obligate intracellular bacterium, is the agent of Q fever . The chronic form of the disease is associated with the overproduction of interleukin-10 and deficient C . burnetii killing by monocytes . We hypothesized that the replication of C . burnetii inside monocytes requires a macrophage-deactivating cytokine such as interleukin-10 . In the absence of interleukin-10, C . burnetii survived but did not replicate in monocytes . C . burnetii replication (measured 15 days) was induced in interleukin-10-treated monocytes . This effect of interleukin-10 is specific since transforming growth factor beta1 had no effect on bacterial replication . C . burnetii replication involves the down-modulation of tumor necrosis factor (TNF) release . First, interleukin-10 suppressed C . burnetii-stimulated production of TNF . Second, the addition of recombinant TNF to interleukin-10-treated monocytes inhibited bacterial replication . Third, the incubation of infected monocytes with neutralizing anti-TNF antibodies favored C . burnetii replication . On the other hand, deficient C . burnetii killing by monocytes from patients with chronic Q fever involves interleukin-10 . Indeed, C . burnetii replication was observed in monocytes from patients with Q fever endocarditis, but not in those from patients with acute Q fever . Bacterial replication was inhibited by neutralizing anti-interleukin-10 antibodies . As monocytes from patients with endocarditis overproduced interleukin-10, the defective bacterial killing is likely related to endogenous interleukin-10 . These results suggest that interleukin-10 enables monocytes to support C . burnetii replication and to favor the development of chronic Q fever.

Dis Aquat Organ, 2001 Jan 26, 44(1), 17 - 27
Recombinant vaccines against infectious hematopoietic necrosis virus: production by the Caulobacter crescentus S-layer protein secretion system and evaluation in laboratory trials; Simon B et al.; We report the development of an IHNV vaccine produced by a new protein production system based on the bacterium Caulobacter crescentus . The subunit vaccines that were tested contain a 184 amino acid segment of the IHNV glycoprotein in different fusion arrangements with the C . crescentus S-layer protein . Relative percent survival of 26 to 34% was demonstrated in rainbow trout fry for a vaccine that contained the 184 amino acid segment of the IHNV glycoprotein fused to the C-terminal one-quarter of the S-layer protein . Inclusion of the universal mammalian T-cell epitopes developed from the measles fusion protein or the tetanus toxin protein did not increase the effectiveness of the IHNV-G/S-layer recombinant protein.

Syst Appl Microbiol, 2000 Dec, 23(4), 479 - 86
Partial sequencing of the hrpB and endoglucanase genes confirms and expands the known diversity within the Ralstonia solanacearum species complex; Poussier S et al.; We determined partial hrpB and endoglucanase genes sequences for 30 strains of Ralstonia solanacearum and one strain of the blood disease bacterium (BDB), a close relative of Ralstonia solanacearum . Sequence comparisons showed high levels of variability within these two regions of the genome involved in pathogenicity . Phylogenetic analysis based upon sequence comparisons of these two regions revealed three major clusters comprising all Ralstonia solanacearum isolates, the BDB strain constituted a phylogenetically distinct entity . Cluster 1 and cluster 2 corresponded to the previously defined divisions 1 and 2 of Ralstonia solanacearum . Moreover, two subclusters could be identified within cluster 2 . The last cluster, designated cluster 3 in this study, included biovar 1 and N2 strains originating from Africa . This recently described group of strains was confirmed to be clearly different from the other strains suggesting a separate evolution from those of both divisions 1 and 2.

ALTEX, 2001, 18(1), 29 - 33
{100 years of erysipelas prophylaxis: significance and reduction of animal experiments}; Cussler K et al.; The history of erysipelas prophylaxis began in 1882 when Pasteur first discovered the attenuating effect of rabbit passages on the erysipelas bacterium . Ten years later, the German veterinarian Lorenz demonstrated the protecting effect of erysipelas antiserum . He developed a method of serovaccination which was successfully used in Germany for more than 50 years . Both scientists employed laboratory animals for the development of their live vaccines . Lorenz additionally recommended an animal model with grey mice to control the potency of erysipelas sera . In 1944, Fortner and Dinter published the results of their investigation on a skin scarification test in swine . This modus of infection was the basis of the first reliable model for efficacy testing of erysipelas vaccines in domestic animals . Shortly after World War II, the first inactivated erysipelas vaccines were being developed . At that time, also a strict quality control was introduced for this product group which required extensive animal experiments in laboratory mice and pigs for the determination of efficacy . WHO established International Standards for erysipelas vaccines and antisera concerning potency testing in mice . These animal models were finally incorporated in pharmacopoeia monographs . Animal experiments have played an important role in the development and quality control of erysipelas vaccines . And the success of this quality control based on animal experiments has had a significant impact on the quality control systems for veterinary vaccines in general . Today, we have a far more detailed knowledge about pathogenesis and immunology of swine erysipelas . This knowledge now allows the introduction of alternative methods according to the 3R concept . With these new methods, animal numbers can be decreased and suffering caused by challenge infection can be reduced . The ultimate goal, i.e . quality control of erysipelas vaccines carried out without routine performance of animal experiments, should be achieved in the near future.

Eur J Biochem, 2001 Mar, 268(6), 1670 - 8
ATP-citrate lyase from the green sulfur bacterium Chlorobium limicola is a heteromeric enzyme composed of two distinct gene products; Kanao T et al.; The reductive tricarboxylic acid cycle functions as a carbon dioxide fixation pathway in the green sulfur bacterium, Chlorobium limicola . ATP-citrate lyase, one of the key enzymes of this cycle, was partially purified from C . limicola strain M1 and the N-terminal sequence of a 65-kDa protein was found to show similarity toward eukaryotic ATP-citrate lyase . A DNA fragment was amplified with primers designed from this sequence and an internal sequence highly conserved among eukaryotic enzymes . Using this fragment as a probe, we isolated a DNA fragment containing two adjacent open reading frames, aclB (1197 bp) and aclA (1827 bp), whose products showed significant similarity to the N- and C-terminal regions of the human enzyme, respectively . Heterologous expression of these genes in Escherichia coli showed that both gene products were essential for ATP-citrate lyase activity . The recombinant enzyme was purified from the cell-free extract of E . coli harboring aclBA for further characterization . The molecular mass of the recombinant enzyme was determined to be approximately 532--557 kDa by gel-filtration . The enzyme catalyzed the cleavage of citrate in an ATP(-), CoA- and Mg(2+)-dependent manner, where ATP and Mg(2+) could be replaced by dATP and Mn(2+), respectively . ADP and oxaloacetate inhibited the reaction . These properties suggested that ATP-citrate lyase from C . limicola controlled the cycle flux depending on intracellular energy conditions . This paper provides the first direct evidence that a bacterial ATP-citrate lyase is a heteromeric enzyme, distinct from mammalian enzymes.

FEMS Microbiol Ecol, 2001 Mar, 35(1), 85 - 95
Phylogenetic analysis of the succession of bacterial communities in the Great South Bay (Long Island); Kelly KM et al.; Bacterial community composition and succession were examined over the course of the summer season in the Great South Bay, Long Island, NY, USA, using a 16S rDNA clone library approach . There was a progression of changes in dominant species in the libraries during the summer of 1997 . The July library had several groups dominant, the SAR407 relatives of the alpha-Proteobacteria (24%) and the SAR86 (18%), sulfur-oxidizing symbiont relatives (8%) of the gamma-Proteobacteria, and unidentified Cytophaga-Flexibacter representatives (22%) . In August, the Cytophaga-Flexibacter (Gelidibacter sp . and unidentified Cytophaga-Flexibacter representative) and Cyanobacteria (Synechococcus sp.) increased to 28% and 14%, respectively . High GC Gram-positives appeared at 18%, and beta-Proteobacteria (Ralstonia sp.) at 10% . By September these groups had either declined or were absent, while the SAR86 cluster, Pseudoalteromonas and Alteromonas of the gamma-Proteobacteria were dominant in the community (61%) . The dominance of open ocean bacteria along with the presence of Aureococcus anophagefferens (Pelagophyceae) in July suggests possible open ocean coupling to bloom events . Many clones in this study were related to previously described clones from a wide distribution of marine environments, substantiating the cosmopolitan nature of pelagic bacteria . Only one isolated bacterium was closely related to 16S rDNA found in the August library.

FEMS Microbiol Ecol, 2001 Mar, 35(1), 67 - 73
Inhibition of algal spore germination by the marine bacterium Pseudoalteromonas tunicata; Egan S et al.; A collection of 56 bacteria isolated from different surfaces in the marine environment were assayed for their effects on the germination of spores from the common green alga Ulva lactuca . Thirteen bacterial isolates were shown to inhibit spore germination . Of these bacteria, Pseudoalteromonas tunicata displayed the most pronounced effects against algal spores . Further characterisation of the anti-algal activity of P . tunicata was performed and it was found that this bacterium produces an extracellular component with specific activity toward algal spores that is heat-sensitive, polar and between 3 and 10 kDa in size . This biologically active compound was also found to prevent the germination of spores from the red alga Polysiphonia sp . and, given the widespread occurrence of P . tunicata in a range of marine habitats, this may suggest that it is effective against a variety of marine algae.

FEMS Microbiol Ecol, 2001 Mar, 35(1), 11 - 17
Feasibility of using GFP-expressing Escherichia coli, coupled with fluorimetry, to determine protozoan ingestion rates; Parry JD et al.; The feasibility of using a live Escherichia coli population, which had been engineered to express the green fluorescent protein (GFP), coupled with fluorimetry, was tested as a means for determining protozoan ingestion rates . Its potential use was based on evidence that once cells are acidified, e.g . in a food vacuole, the fluorescence is lost . Of the 29 protozoa tested, over 85% ingested the GFP-expressing E . coli and a detailed experiment with the ciliate Tetrahymena pyriformis was carried out, principally to assess the performance of the live bacterium against two commonly used surrogate prey, i.e . fluorescently labelled bacteria (FLB) and fluorescently labelled microspheres (FLMs) . A decrease in GFP-expressing E . coli fluorescence and, hence, concentration, was recorded by fluorimetry and epifluorescence microscopy, with calculated ingestion rates being equivalent . A higher ingestion rate was determined by counting the number of fluorescent E . coli within the ciliate over 120 s, but this was equivalent to that obtained for the stained E . coli using the same direct method of analysis . However, the ciliate was shown to process the stained and unstained E . coli cells differently, with only the latter resulting in an increase in ciliate abundance.

FEBS Lett, 2001 Mar 9, 492(1-2), 33 - 8
ctr1, a gene involved in a signal transduction pathway of the gliding motility in the cyanobacterium Synechocystis sp . PCC 6803; Chung YH et al.; We generated random Tn5 mutations in Synechocystis sp . PCC 6803 in search for genes involved in the signal transduction cascade for the cyanobacterial gliding motility . One of the non-gliding Tn5 mutants, S1-105, had an insertional inactivation in the slr1044 gene encoding a putative methyl-accepting chemotaxis protein . Interposon mutation on the slr1044 (named ctr1) in the bacterium also eliminated gliding motility . In the interposon mutant, the expression of pilA1 was 5-fold decreased compared with that of wild-type and thick pili, that are believed to be the motor for gliding, could not be observed by an electron microscope . Therefore, we suggest that the Ctr1 protein functions as a transducer that regulates the expression of pilA1, and thus is required for the biogenesis of thick pili.

Biochim Biophys Acta, 2001 May 1, 1505(1), 108 - 20
The Na(+) cycle in Acetobacterium woodii: identification and characterization of a Na(+) translocating F(1)F(0)-ATPase with a mixed oligomer of 8 and 16 kDa proteolipids; Muller V et al.; The homoacetogenic bacterium Acetobacterium woodii relies on a sodium ion current across its cytoplasmic membrane for energy-dependent reactions . The sodium ion potential is established by a yet to be identified primary, electrogenic pump connected to the Wood-Ljungdahl pathway . Reactions possibly involved in Na(+) export are discussed . The electrochemical sodium ion potential generated is used to drive endergonic reactions such as flagellar rotation and ATP synthesis . Biochemical and molecular data identified the Na(+)-ATPase of A . woodii as a typical member of the F(1)F(0) class of ATPases . Its catalytic properties and the hypothetical sodium ion binding site in subunit c are discussed . The encoding genes were cloned and, surprisingly, the atp operon was shown to contain multiple copies of genes encoding subunit c . Two copies encode identical 8 kDa proteolipids, and a third copy arose by duplication and subsequent fusion of two genes . Furthermore, the duplicated subunit c does not contain the ion binding site in hair pin two . Biochemical and molecular data revealed that all three copies of subunit c constitute a mixed oligomer . The evolution of the structure and function of subunit c in ATPases from eucarya, bacteria, and archaea is discussed.

J Periodontal Res, 2001 Feb, 36(1), 40 - 7
Involvement of caspases in apoptotic cell death of murine macrophages infected with Actinobacillus actinomycetemcomitans; Nonaka K et al.; Infection of murine macrophages in vitro with periodontopathic bacterium Actinobacillus actinomycetemcomitans induces apoptotic cell death . In this study, we investigated the involvement of caspases in apoptotic cell death of A . actinomycetemcomitans-infected macrophages . Two peptide inhibitors of caspases, benzyloxycarbonyl-Val-Ala-Asp (OMe)-fluoromethyl ketone (Z-VAD-FMK) and benzyloxycarbonyl-Asp-Glu-Val-Asp (OMe)-fluoromethyl ketone (Z-DEVD-FMK), inhibited apoptotic cell death of murine macrophage cell line J774.1 infected with A . actinomycetemcomitans . During the process of apoptosis, interleukin-1beta (IL-1beta) was detected in the culture supernatants of J774.1 cells . IL-1beta secretion was blocked by the caspase-1 inhibitor, Z-VAD-FMK, indicating that caspase-1 is involved in not only the induction of apoptosis but also the IL-1beta secretion from A . actinomycetemcomitans-infected J774.1 cells . Immunoblot analysis revealed that the infection of A . actinomycetemcomitans to J774.1 cells induced the cleavage of retinoblastoma protein (Rb), suggesting that caspase-3 was activated by A . actinomycetemcomitans infection . The cytosol from A . actinomycetemcomitans-infected J774.1 cells induced Rb proteolysis in vitro, which was inhibited by the caspase-3 inhibitor, Z-DEVD-FMK . Furthermore, caspase-3-like activity was markedly increased in J774.1 cells infected with A.actinomycetemcomitans between 12 h and 24 h, which was subsequently inhibited by the addition of caspase-3 inhibitor, Z-DEVD-FMK . These findings indicate that caspase-3 induces apoptosis in J774.1 cells infected with A . actinomycetemcomitans . Taken together, these results suggest that caspase-1 and caspase-3 are involved in the induction of apoptosis in A . actinomycetemcomitans-infected macrophages.

Jpn J Pharmacol, 2001 Jan, 85(1), 84 - 91
Suppression of gingival inflammation induced by Porphyromonas gingivalis in rats by leupeptin; Kitano S et al.; In this study, we developed a procedure to produce gingivitis in rats by inoculation of Porphyromonas gingivalis and studied the contribution of the bacterial cysteine proteinases, Arg-gingipain (Rgp) and Lys-gingipain (Kgp), to the pathology in the gingiva . To adhere the bacterium to periodontal tissues, a cotton thread was inserted between the first and second molar of right maxillary sites of rats . Rats in group A were administered with vehicle alone after bacterial (strain W83) inoculation . In group B, the bacteria were inoculated in combination with leupeptin, a potent inhibitor of Rgp and Kgp, and then leupeptin alone was administered the week after . Rats in group C were administered leupeptin for 6 weeks after bacteria inoculation . All left maxillary gingiva in three groups showed no inflammatory changes . Right maxillary gingiva of group A showed most of the clinical landmarks of gingivitis . Leupeptin exhibited only a little inhibitory effect on this gingivitis in group B, whereas it had a strong inhibitory effect on the inflammation in group C . These results suggest that P . gingivalis-induced gingivitis is attributable to Rgp and Kgp and that leupeptin is more effective in the late phase than the early stage of gingivitis.

J Vet Diagn Invest, 2001 Jan, 13(1), 87 - 8
An enzyme-linked immunosorbent assay for the convenient serodiagnosis of contagious equine metritis in mares; Katz J et al.; An enzyme-linked immunosorbent assay (ELISA) was developed for the serodiagnosis of contagious equine metritis (CEM), a sexually transmitted disease caused by Taylorella equigenitalis . Antigen preparation was simple, and antigens derived from both classical and atypical forms of T . equigenitalis enabled detection of antibody responses elicted in horses experimentally exposed to either form of the bacterium . Sera serially obtained from these horses from 0 to 63 days postexposure were tested by the traditional complement fixation test (CFT) for CEM and with the ELISA, using both antigens separately . There was close agreement between CFT and ELISA methodologies during the postexposure time period used to detect CEM serodiagnostically in regulatory animal health testing programs . Unlike the CFT, which requires an overnight incubation step, the ELISAs are more convenient and can be completed in 3 hours.

Trends Microbiol, 2001 Mar, 9(3), 126 - 9
Lipid chemotaxis and signal transduction in Myxococcus xanthus; Kearns DB et al.; The lipid phosphatidylethanolamine (PE) is the first chemoattractant to be described for a surface-motile bacterium . In Myxococcus xanthus, the specific activity of PE is determined by its fatty acid components . Two active species have been identified: dilauroyl PE and dioleoyl PE . Excitation to dilauroyl PE requires fibril appendages and the presence of two cytoplasmic chemotaxis systems, of which one (Dif) appears to mediate excitation and the other (Frz) appears to mediate adaptation . A possible mechanism for fibril-mediated signal transduction is discussed, along with the potential roles for PE chemotaxis in the context of the M . xanthus life cycle.

Mol Gen Mikrobiol Virusol, 2001, (1), 28 - 32
{A method of genotyping clinical isolates of Ureaplasma urealyticum biovar Parvo}; Ekimov AN et al.; A new method for typing clinical isolates of U . urealyticum (Parvo biovar) is based on SSCP analysis of amplicons of mba gene 5' region and upstream region . The mba gene is coding for MB gene of U . urealyticum . This method allows genotyping of U . urealyticum isolates using vaginal and cervical swabs without culturing . Sixty-two clinical specimens from patients with a history of chronic cystitis, chronic pyelonephritis, chronic salpingo-oophoritis, erosion of the cervix uteri, and spontaneous abortions were tested for U . urealyticum . The bacterium was detected in 64% (40 specimens), 83% (33) of which belonged to Parvo biovar . Parvo biovar isolates were analyzed and genotyped as follows: first genotype 52%, second genotype 33%, and third genotype 16% . Further sequencing of the first and second genotype amplicons showed that the first genotype belonged to serotype 3 and second genotype to serotype 6.

Stomatologiia (Mosk), 2001, 80(1), 20 - 2
{Status of oral mucosa and periodontal tissue in children with gastroduodenal diseases associated with Helicobacter pylori}; Urazova RZ et al.; General and dental status was evaluated in 64 children aged 5-14 years with active chronic gastroduodenitis and gastroduodenal ulcer . Helicobacter pylori was detected by the urease test and morphological analysis of gastric biopsy specimens with subsequent Giemsa or toluidine blue staining . The presence of Helicobacter pylori was confirmed by immunohistochemical analysis with monoclonal antibodies to this bacterium using DAKO kits . Children with gastroduodenal diseases often suffer from chronic catarrhal gingivitis liable to generalization and often develop pronounced changes in the mucosa of the tongue and red lips.

J Dairy Sci, 2001 Feb, 84(2), 524 - 7
On-farm batch pasteurization destroys Mycobacterium paratuberculosis in waste milk; Stabel JR; A recent dairy survey conducted in 1996 by the National Animal Health Monitoring System suggests between 20 and 40% of dairy herds in the United States have some level of Johne's disease . This figure will continue to increase unless producers implement management regimes that will help control the spread of this disease within their herds . The neonatal calf is the target for infection with Mycobacterium paratuberculosis, the causative agent of Johne's disease . Calves become infected via exposure to the bacterium through contaminated feces, bedding, colostrum, and milk . Shedding of viable M . paratuberculosis has been documented in the colostrum and milk of infected dams . This study evaluated the efficacy of on-farm pasteurization to destroy M . paratuberculosis in waste milk fed to calves to circumvent this mode of transmission . In three replicate experiments, waste milk was experimentally inoculated with M . paratuberculosis and heated at 65.5 degrees C for 30 min . No viable bacteria were recovered after 28 wk of incubation . These results suggest that batch pasteurization of waste milk contaminated with M . paratuberculosis was effective at generating a clean product to feed to young calves.

J Cardiovasc Surg (Torino), 2000 Dec, 41(6), 829 - 33
Ischemic cardiovascular disease and Helicobacter pylori . Where is the link?
Pellicano R, Oliaro E, Gandolfo N, Aruta E, Mangiardi L, Orzan F, Bergerone S, Rizzetto M, Ponzetto A.
Coronary heart disease (CHD) is the leading cause of death in western countries . Although several major risk factors have been identified, they fail to account for all the epidemiological variants of the disease, thus warranting research into novel causal agents . Cardiovascular diseases have long been associated with chronic infections acting through the activation of inflammatory pathways, and antibiotic therapy has been shown to produce a dramatic decrease in the rate of disease recurrence in patients with a history of myocardial infarction or unstable angina . The link between Helicobacter pylori (H . pylori) infection and CHD, first described by Mendall et al . in 1994, has been the subject of a multitude of epidemiological and clinical studies; however, these have been so heterogeneous that not two of them are based on a comparable selection of patients and focused on the same kind of disease, e.g . stable coronary heart disease or acute myocardial infarction . Evidence from animal studies supports the thesis that H . pylori plays an extremely important role in the acute phase of myocardial infarction: the bacterium causes platelet aggregation and induces pro-coagulant activity in experimentally infected mice . H . pylori may also contribute to atherosclerosis through an auto-immune process against endothelial cells or an increased concentration of homocysteine in the blood due to decreased levels of folic acid and cobalamin . The exact role of H . pylori cannot yet be fully assessed: there is a clear and present need for further studies with appropriate epidemiological and clinical approaches to investigate through prospective and interventional trial the possible causal relationship between H . pylori and CHD.

Eur J Biochem, 2001 Mar, 268(5), 1323 - 31
Novel methylated triterpenoids of the gammacerane series from the nitrogen-fixing bacterium Bradyrhizobium japonicum USDA 110; Bravo JM et al.; The nitrogen-fixing, symbiotic root-nodule forming bacterium Bradyrhizobium japonicum USDA 110 contained gammacerane derivatives next to triterpenoids of the hopane series . Diploptene, diplopterol, 2 beta-methyldiplopterol, aminobacteriohopanetriol and adenosylhopane were accompanied by tetrahymanol and the corresponding novel methylated homologues 2 beta-methyltetrahymanol, 20 alpha-methyltetrahymanol, and 2 beta,20 alpha-dimethyltetrahymanol . Incorporation of {(2)H(3)}methyl-L-methionine indicated that the additional methyl groups originated from methionine, probably with S-adenosylmethionine acting as methyl donor, with retention of the three deuterium atoms . The simultaneous presence of hopane and gammacerane derivatives seems a characteristic feature of the genus Bradyrhizobium and the phylogenetically closely related Rhodopseudomonas palustris.

Vet Microbiol, 2001 Mar 2, 79(1), 47 - 62
Identification and detection of Actinobacillus pleuropneumoniae by PCR based on the gene apxIVA; Schaller A et al.; The apxIVA gene, a recently discovered RTX determinant of Actinobacillus pleuropneumoniae, was shown to be species-specific . DNA hybridization experiments using probes for various regions of apxIVA revealed that the 3'-terminus of this gene was present in all 14 serotypes of A . pleuropneumoniae but absent from phylogenetically related species . A primer pair spanning this region specifically amplified a 422bp fragment in PCR experiments with DNA from the reference strains of the 14 serotypes and 194 field strains isolated from various geographic locations worldwide . DNA sequence analysis of PCR products derived from all serotypes were identical except in serotypes 3, 8, and 10, which showed minor differences . The PCR did not amplify any product when DNA from 17 different bacterial species closely related to A . pleuropneumoniae was used as template . In addition, the PCR was negative with DNA of several Actinobacillus sp . which were initially characterized as A . pleuropneumoniae using routine phenotypic and serological analyses but which were subsequently shown by 16S rRNA sequence analysis to belong to yet undefined Actinobacillus species . The sensitivity of the PCR was determined to be 10pg of A . pleuropneumoniae DNA . A set of nested primers amplified a 377bp fragment specifically with A . pleuropneumoniae DNA . DNA titration experiments using the flanking and nested primer pairs showed an improved level of sensitivity to approximately 10fg of genomic DNA . The nested PCR was used to monitor the spread of A . pleuropneumoniae in pigs experimentally infected with a virulent serotype 1 strain and housed in a controlled environment facility . A . pleuropneumoniae DNA could be detected by nested PCR in nasal swab samples of infected pigs receiving either a high dose (5x10(5)) or a low dose (1x10(4)) challenge and in unchallenged cohorts that were contact-infected by the inoculated animals . Furthermore, PCR confirmed the presence of A . pleuropneumoniae in 16/17 homogenates from necrotic lung lesions, while the bacterium was successfully recovered from 13 of these lesions by culture.

Science, 2001 Mar 2, 291(5509), 1790 - 2
Biosynthesis of complex polyketides in a metabolically engineered strain of E . coli; Pfeifer BA et al.; The macrocyclic core of the antibiotic erythromycin, 6-deoxyerythronolide B (6dEB), is a complex natural product synthesized by the soil bacterium Saccharopolyspora erythraea through the action of a multifunctional polyketide synthase (PKS) . The engineering potential of modular PKSs is hampered by the limited capabilities for molecular biological manipulation of organisms (principally actinomycetes) in which complex polyketides have thus far been produced . To address this problem, a derivative of Escherichia coli has been genetically engineered . The resulting cellular catalyst converts exogenous propionate into 6dEB with a specific productivity that compares well with a high-producing mutant of S . erythraea that has been incrementally enhanced over decades for the industrial production of erythromycin.

Appl Environ Microbiol, 2001 Mar, 67(3), 1396 - 9
Reductive, coenzyme A-mediated pathway for 3-chlorobenzoate degradation in the phototrophic bacterium Rhodopseudomonas palustris; Egland PG et al.; We isolated a strain of Rhodopseudomonas palustris (RCB100) by selective enrichment in light on 3-chlorobenzoate to investigate the steps that it uses to accomplish anaerobic dechlorination . Analyses of metabolite pools as well as enzyme assays suggest that R . palustris grows on 3-chlorobenzoate by (i) converting it to 3-chlorobenzoyl coenzyme A (3-chlorobenzoyl-CoA), (ii) reductively dehalogenating 3-chlorobenzoyl-CoA to benzoyl-CoA, and (iii) degrading benzoyl-CoA to acetyl-CoA and carbon dioxide . R . palustris uses 3-chlorobenzoate only as a carbon source and thus incorporates the acetyl-CoA that is produced into cell material . The reductive dechlorination route used by R . palustris for 3-chlorobenzoate degradation differs from those previously described in that a CoA thioester, rather than an unmodified aromatic acid, is the substrate for complete dehalogenation.

Appl Environ Microbiol, 2001 Mar, 67(3), 1284 - 91
Spiroplasma symbiont of the pea aphid, Acyrthosiphon pisum (Insecta: Homoptera); Fukatsu T et al.; From a laboratory strain of the pea aphid, Acyrthosiphon pisum, we discovered a previously unknown facultative endosymbiotic bacterium . Molecular phylogenetic analysis based on 16S ribosomal DNA revealed that the bacterium is a member of the genus Spiroplasma . The Spiroplasma organism showed stable vertical transmission through successive generations of the host . Injection of hemolymph from infected insects into uninfected insects established a stable infection in the recipients . The Spiroplasma symbiont exhibited negative effects on growth, reproduction, and longevity of the host, particularly in older adults . Of 58 clonal strains of A . pisum established from natural populations in central Japan, 4 strains possessed the Spiroplasma organism.

Appl Environ Microbiol, 2001 Mar, 67(3), 1239 - 45
Rapid screening method for Mycobactericidal activity of chemical germicides that uses Mycobacterium terrae expressing a green fluorescent protein gene; Zafer AA et al.; The slow growth of mycobacteria in conventional culture methods impedes the testing of chemicals for mycobactericidal activity . An assay based on expression of the green fluorescent protein (GFP) by mycobacteria was developed as a rapid alternative . Plasmid pBEN, containing the gene encoding a red-shifted, high-intensity GFP mutant, was incorporated into Mycobacterium terrae (ATCC 15755), and GFP expression was observed by epifluorescence microscopy . Mycobactericidal activity was assessed by separately exposing a suspension of M . terrae(pBEN) to several dilutions of test germicides based on 7.5% hydrogen peroxide, 2.4% alkaline glutaraldehyde, 10% acid glutaraldehyde, and 15.5% of a phenolic agent for contact times ranging from 10 to 20 min (22 degrees C), followed by culture of the exposed cells in broth (Middlebrook 7H9) and measurement of fluorescence every 24 h . When the fluorescence was to be compared with CFU, the samples were plated on Middlebrook 7H11 agar and incubated for 4 weeks . No increase in fluorescence or CFU occurred in cultures in which the cells had been inactivated by the germicide concentrations tested . Where the test bacterium was exposed to ineffective levels of the germicides, fluorescence increased after a lag period of 1 to 7 days, corresponding to the level of bacterial inactivation . In untreated controls, fluorescence increased rapidly to reach a peak in 2 to 4 days . A good Pearson correlation coefficient (r > or =0.85) was observed between the intensity of fluorescence and the number of CFU . The GFP-based fluorescence assay reduced the turnaround time in the screening of chemical germicides for mycobactericidal activity to < or =7 days.

Water Res, 2001 Mar, 35(3), 835 - 43
Phenanthrene desorption from soil in the presence of bacterial extracellular polymer: observations and model predictions of dynamic behavior; Liu A et al.; The extracellular polymer produced by a bacterium isolated from soil was employed in laboratory studies of desorption of a model polynuelear aromatic hydrocarbon (PAH), phenanthrene . The experimental results show that the selected extracellular polymer enhances the extent of release of soil-bound phenanthrene . A kinetic model was developed as an aid in interpreting the alterations in phenanthrene desorption resulting from polymer addition . The model employs a statistical gamma (gamma) distribution to describe spectrum of rate constants for transfer of phenanthrene from soil to water, and assumes instantaneous binding of phenanthrene to polymer and of polymer to the test soil . The relevant distribution coefficients and statistical parameters of the gamma distribution needed for the model were evaluated in independent experiments . Using these measured parameters, the model provides a satisfactory independent prediction of phenanthrene release from soil to aqueous phase at two test polymer concentrations, 50 mg TOC/L and 100 mg TOC/L . The success of the independent model predictions suggests a mechanism for the influence of extracellular polymer on phenanthrene desorption . The intrinsic, soil-specific, rate constants for solid to solution transfer of phenanthrene do not appear to be changed by bacterial polymer . Instead, polymer binding of phenanthrene in solution results in an increase in driving force for desorption by decreasing the solution concentration of the free, unbound, PAH molecule.

J Biochem (Tokyo), 2001 Mar, 129(3), 411 - 21
Purification and characterization of homo- and hetero-dimeric acetate kinases from the sulfate-reducing bacterium Desulfovibrio vulgaris; Yu L et al.; Two distinct forms of acetate kinase were purified to homogeneity from a sulfate-reducing bacterium Desulfovibrio vulgaris Miyazaki F . The enzymes were separated from the soluble fraction of the cells on anion exchange columns . One acetate kinase (AK-I) was a homodimer (alpha(S)(2)) and the other (AK-II) was a heterodimer (alpha(S)alpha(L)) . On SDS-PAGE, alpha(L) and alpha(S) subunits migrated as bands of 49.3 and 47.8 kDa, respectively, but they had an identical N-terminal amino acid sequence . A rapid HPLC method was developed to directly measure ADP and ATP in assay mixtures . Initial velocity data for AK-I and AK-II were collected by this method and analyzed based on a random sequential mechanism, assuming rapid equilibrium for the substrate binding steps . All kinetic parameters for both the forward acetyl phosphate formation and the reverse ATP formation catalyzed by AK-I and AK-II were successfully determined . The two enzymes showed similar kinetic properties in Mg(2+) requirement, pH-dependence and magnitude of kinetic parameters . These results suggest that two forms of acetate kinase are produced to finely regulate the enzyme function by post-translational modifications of a primary gene product in Desulfovibrio vulgaris.

Microbes Infect, 2001 Jan, 3(1), 11 - 21
Orientia tsutsugamushi infection: overview and immune responses; Seong SY et al.; Orientia tsutsugamushi, an obligate intracellular bacterium, was isolated for the first time in 1930 . Infections by virulent strains are characterized by fever, rash, eschar, pneumonia, myocarditis, and disseminated intravascular coagulation . Here we review the general aspects of O . tsutsugamushi and immune responses in terms of inflammation, protective immune mechanisms, and immunogenic antigens.

FEBS Lett, 2001 Feb 23, 491(1-2), 143 - 7
Probing the binding sites of exchanged chlorophyll a in LH2 by Raman and site-selection fluorescence spectroscopies; Gall A et al.; In this work we have selectively released the 800 nm absorbing bacteriochlorophyll a molecules of the LH2 protein from the photosynthetic bacterium Rhodopseudomonas acidophila, strain 10050, and replaced them with chlorophyll a (Chla) . A combination of low-temperature electronic absorption, resonance Raman and site-selection fluorescence spectroscopies revealed that the Chla pigments are indeed bound in the B800 binding site; this is the first work that formally proves that such non-native chlorins can be inserted correctly into LH2.

EMBO J, 2001 Jan 15, 20(1-2), 231 - 9
A primordial tRNA modification required for the evolution of life?
Bjork GR, Jacobsson K, Nilsson K, Johansson MJ, Bystrom AS, Persson OP.
The evolution of reading frame maintenance must have been an early event, and presumably preceded the emergence of the three domains Archaea, Bacteria and Eukarya . Features evolved early in reading frame maintenance may still exist in present-day organisms . We show that one such feature may be the modified nucleoside 1-methylguanosine (m(1)G37), which prevents frameshifting and is present adjacent to and 3' of the anticodon (position 37) in the same subset of tRNAs from all organisms, including that with the smallest sequenced genome (Mycoplasma genitalium), and organelles . We have identified the genes encoding the enzyme tRNA(m(1)G37)methyltransferase from all three domains . We also show that they are orthologues, and suggest that they originated from a primordial gene . Lack of m(1)G37 severely impairs the growth of a bacterium and a eukaryote to a similar degree . Yeast tRNA(m(1)G37)methyltransferase also synthesizes 1-methylinosine and participates in the formation of the Y-base (yW) . Our results suggest that m(1)G37 existed in tRNA before the divergence of the three domains, and that a tRNA(m(1)G37)methyltrans ferase is part of the minimal set of gene products required for life.

J Bacteriol, 2001 Mar, 183(6), 2013 - 24
Mobile cytochrome c2 and membrane-anchored cytochrome cy are both efficient electron donors to the cbb3- and aa3-type cytochrome c oxidases during respiratory growth of Rhodobacter sphaeroides; Daldal F et al.; We have recently established that the facultative phototrophic bacterium Rhodobacter sphaeroides, like the closely related Rhodobacter capsulatus species, contains both the previously characterized mobile electron carrier cytochrome c2 (cyt c2) and the more recently discovered membrane-anchored cyt cy . However, R . sphaeroides cyt cy, unlike that of R . capsulatus, is unable to function as an efficient electron carrier between the photochemical reaction center and the cyt bc1 complex during photosynthetic growth . Nonetheless, R . sphaeroides cyt cy can act at least in R . capsulatus as an electron carrier between the cyt bc1 complex and the cbb3-type cyt c oxidase (cbb3-Cox) to support respiratory growth . Since R . sphaeroides harbors both a cbb3-Cox and an aa3-type cyt c oxidase (aa3-Cox), we examined whether R . sphaeroides cyt cy can act as an electron carrier to either or both of these respiratory terminal oxidases . R . sphaeroides mutants which lacked either cyt c2 or cyt cy and either the aa3-Cox or the cbb3-Cox were obtained . These double mutants contained linear respiratory electron transport pathways between the cyt bc1 complex and the cyt c oxidases . They were characterized with respect to growth phenotypes, contents of a-, b-, and c-type cytochromes, cyt c oxidase activities, and kinetics of electron transfer mediated by cyt c2 or cyt cy . The findings demonstrated that both cyt c2 and cyt cy are able to carry electrons efficiently from the cyt bc1 complex to either the cbb3-Cox or the aa3-Cox . Thus, no dedicated electron carrier for either of the cyt c oxidases is present in R . sphaeroides . However, under semiaerobic growth conditions, a larger portion of the electron flow out of the cyt bc1 complex appears to be mediated via the cyt c2-to-cbb3-Cox and cyt cy-to-cbb3-Cox subbranches . The presence of multiple electron carriers and cyt c oxidases with different properties that can operate concurrently reveals that the respiratory electron transport pathways of R . sphaeroides are more complex than those of R . capsulatus.

J Bacteriol, 2001 Mar, 183(6), 1945 - 53
Cellulosomal scaffoldin-like proteins from Ruminococcus flavefaciens; Ding SY et al.; Two tandem cellulosome-associated genes were identified in the cellulolytic rumen bacterium, Ruminococcus flavefaciens . The deduced gene products represent multimodular scaffoldin-related proteins (termed ScaA and ScaB), both of which include several copies of explicit cellulosome signature sequences . The scaB gene was completely sequenced, and its upstream neighbor scaA was partially sequenced . The sequenced portion of scaA contains repeating cohesin modules and a C-terminal dockerin domain . ScaB contains seven relatively divergent cohesin modules, two extremely long T-rich linkers, and a C-terminal domain of unknown function . Collectively, the cohesins of ScaA and ScaB are phylogenetically distinct from the previously described type I and type II cohesins, and we propose that they define a new group, which we designated here type III cohesins . Selected modules from both genes were overexpressed in Escherichia coli, and the recombinant proteins were used as probes in affinity-blotting experiments . The results strongly indicate that ScaA serves as a cellulosomal scaffoldin-like protein for several R . flavefaciens enzymes . The data are supported by the direct interaction of a recombinant ScaA cohesin with an expressed dockerin-containing enzyme construct from the same bacterium . The evidence also demonstrates that the ScaA dockerin binds to a specialized cohesin(s) on ScaB, suggesting that ScaB may act as an anchoring protein, linked either directly or indirectly to the bacterial cell surface . This study is the first direct demonstration in a cellulolytic rumen bacterium of a cellulosome system, mediated by distinctive cohesin-dockerin interactions.

J Bacteriol, 2001 Mar, 183(6), 1899 - 908
Reinvestigation of a new type of aerobic benzoate metabolism in the proteobacterium Azoarcus evansii; Mohamed ME et al.; The aerobic metabolism of benzoate in the proteobacterium Azoarcus evansii was reinvestigated . The known pathways leading to catechol or protocatechuate do not operate in this bacterium . The presumed degradation via 3-hydroxybenzoyl-coenzyme A (CoA) and gentisate could not be confirmed . The first committed step is the activation of benzoate to benzoyl-CoA by a specifically induced benzoate-CoA ligase (AMP forming) . This enzyme was purified and shown to differ from an isoenzyme catalyzing the same reaction under anaerobic conditions . The second step postulated involves the hydroxylation of benzoyl-CoA to a so far unknown product by a novel benzoyl-CoA oxygenase, presumably a multicomponent enzyme system . An iron-sulfur flavoprotein, which may be a component of this system, was purified and characterized . The homodimeric enzyme had a native molecular mass of 98 kDa as determined by gel filtration and contained 0.72 mol flavin adenine dinucleotide (FAD), 10.4 to 18.4 mol of Fe, and 13.3 to 17.9 mol of acid-labile sulfur per mol of native protein, depending on the method of protein determination . This benzoate-induced enzyme catalyzed a benzoyl-CoA-, FAD-, and O2-dependent NADPH oxidation surprisingly without hydroxylation of the aromatic ring; however, H2O2 was formed . The gene (boxA, for benzoate oxidation) coding for this protein was cloned and sequenced . It coded for a protein of 46 kDa with two amino acid consensus sequences for two {4Fe-4S} centers at the N terminus . The deduced amino acid sequence showed homology with subunits of ferredoxin-NADP reductase, nitric oxide synthase, NADPH-cytochrome P450 reductase, and phenol hydroxylase . Upstream of the boxA gene, another gene, boxB, encoding a protein of 55 kDa was found . The boxB gene exhibited homology to open reading frames in various other bacteria which code for components of a putative aerobic phenylacetyl-CoA oxidizing system . The boxB gene product was one of at least five proteins induced when A . evansii was grown on benzoate.

Biophys J, 2001 Mar, 80(3), 1591 - 603
Spectroscopy on the B850 band of individual light-harvesting 2 complexes of Rhodopseudomonas acidophila . I . Experiments and Monte Carlo simulations; Ketelaars M et al.; The electronic structure of the circular aggregate of 18 bacteriochlorophyll a (BChl a) molecules responsible for the B850 absorption band of the light-harvesting 2 (LH2) complex of the photosynthetic purple bacterium Rhodopseudomonas acidophila has been studied by measuring fluorescence-excitation spectra of individual complexes at 1.2 K . The spectra reveal several well-resolved bands that are obscured in the single, broad B850 band observed in conventional absorption measurements on bulk samples . They are interpreted consistently in terms of the exciton model for the circular aggregate of BChl a molecules . From the energy separation between the different exciton transitions a reliable value of the intermolecular interaction is obtained . The spectra of the individual complexes allow for a distinction between the intra- and the intercomplex disorder . In addition to the random disorder, a regular modulation of the interaction has to be assumed to account for all the features of the observed spectra . This modulation has a C(2) symmetry, which strongly suggests a structural deformation of the ring into an ellipse.

Biophys J, 2001 Mar, 80(3), 1487 - 97
Effect of high pressure on the photochemical reaction center from Rhodobacter sphaeroides R26.1; Gall A et al.; High-pressure studies on the photochemical reaction center from the photosynthetic bacterium Rhodobacter sphaeroides, strain R26.1, shows that, up to 0.6 GPa, this carotenoid-less membrane protein does not loose its three-dimensional structure at room temperature . However, as evidenced by Fourier-transform preresonance Raman and electronic absorption spectra, between the atmospheric pressure and 0.2 GPa, the structure of the bacterial reaction center experiences a number of local reorganizations in the binding site of the primary electron donor . Above that value, the apparent compressibility of this membrane protein is inhomogeneous, being most noticeable in proximity to the bacteriopheophytin molecules . In this elevated pressure range, no more structural reorganization of the primary electron donor binding site can be observed . However, its electronic structure becomes dramatically perturbed, and the oscillator strength of its Q(y) electronic transition drops by nearly one order of magnitude . This effect is likely due to very small, pressure-induced changes in its dimeric structure.

Carbohydr Res, 2001 Jan 30, 330(2), 231 - 9
Structure of an acidic polysaccharide from a marine bacterium Pseudoalteromonas distincta KMM 638 containing 5-acetamido-3,5,7,9-tetradeoxy-7-formamido-L-glycero-L-manno-nonulosonic acid; Muldoon J et al.; An acidic polysaccharide was obtained from the lipopolysaccharide of Pseudoalteromonas distincta strain KMM 638, isolated from a marine sponge, and found to contain D-GlcA, D-GalNAc, 2-acetamido-2,6-dideoxy-D-glucose (D-QuiNAc) and two unusual acidic amino sugars: 2-acetamido-2-deoxy-D-galacturonic acid (D-GalNAcA) and 5-acetamido-3,5,7,9-tetradeoxy-7-formamido-L-glycero-L-manno-nonulosonic acid (Pse5Ac7Fo, a derivative of pseudaminic acid) . Oligosaccharides were derived from the polysaccharide by partial acid hydrolysis and mild alkaline degradation and characterised by electrospray ionisation (ESI) MS and 1H and 13C NMR spectroscopy . Based on these data and NMR spectroscopic studies of the initial and O-deacetylated polysaccharides, including quaternary carbon detection, 2D COSY, TOCSY, ROESY, H-detected 1H,13C HMQC and HMBC experiments, the following structure of the branched pentasaccharide repeating unit was established: {structure: see text}.

Rinsho Byori, 2000 Dec, 48(12), 1157 - 63
{Nosocomial infection monitoring system featuring detection of local clustering}; Sato K et al.; We have developed a nosocomial infection surveillance system making use of data from laboratory information system . The system makes cross-reference table of detected bacteria according to either the site of occurrence(hospital wards) or antibiotic sensitivity . It is capable of listing all the patients or serial changes in frequency for any specified bacterium . Furthermore, we have developed an algorism to detect local clustering . For each ward, the system calculates all combinations of distance between beds of patients with specified bacteria . We named the statistics as DC(degree of cluster) and its significance was judged by a confidence interval of DC obtained by a bootstrap method by randomly assigning the same number of patients to the beds in the same wards . Retrospective analysis of the distribution of 4 major bacteria in the wards proved that DC is a sensitive indicator of local clustering.

DNA Res, 2000 Dec 31, 7(6), 331 - 8
Complete genome structure of the nitrogen-fixing symbiotic bacterium Mesorhizobium loti; Kaneko T et al.; The complete nucleotide sequence of the genome of a symbiotic bacterium Mesorhizobium loti strain MAFF303099 was determined . The genome of M . loti consisted of a single chromosome (7,036,071 bp) and two plasmids, designated as pMLa (351,911 bp) and pMLb (208, 315 bp) . The chromosome comprises 6752 potential protein-coding genes, two sets of rRNA genes and 50 tRNA genes representing 47 tRNA species . Fifty-four percent of the potential protein genes showed sequence similarity to genes of known function, 21% to hypothetical genes, and the remaining 25% had no apparent similarity to reported genes . A 611-kb DNA segment, a highly probable candidate of a symbiotic island, was identified, and 30 genes for nitrogen fixation and 24 genes for nodulation were assigned in this region . Codon usage analysis suggested that the symbiotic island as well as the plasmids originated and were transmitted from other genetic systems . The genomes of two plasmids, pMLa and pMLb, contained 320 and 209 potential protein-coding genes, respectively, for a variety of biological functions . These include genes for the ABC-transporter system, phosphate assimilation, two-component system, DNA replication and conjugation, but only one gene for nodulation was identified.

Ann Trop Med Parasitol, 2000 Dec, 94(8), 801 - 16
Antibiotics and Wolbachia in filarial nematodes: antifilarial activity of rifampicin, oxytetracycline and chloramphenicol against Onchocerca gutturosa, Onchocerca lienalis and Brugia pahangi; Townson S et al.; The activity against filarial parasites of the antibiotics rifampicin, oxytetracycline and chloramphenicol was examined . In addition, transmission electron microscopy was used to study the effects of rifampicin and oxytetracycline on filarial tissues and on the endosymbiont bacterium, Wolbachia . When tested in vitro at a concentration of 50.0 microM, each of the three antibiotics significantly reduced the motility levels of male Onchocerca gutturosa . Rifampicin, however, was the most active, virtually immobilizing the parasite by the end of the 40-day trial and producing an 84% reduction in viability (as measured by formazan-based colorimetry) . In tests against O . lienalis microfilariae (mff) in CBA mice, the numbers of mff recovered after treatment with oxytetracycline at 100, 25 or 6.5 mg/kg daily, for 15 days, were 56% (P < or = 0.03), 38% (P> 0.05) and 45% (P = 0.05) less than that recovered from the untreated controls, respectively . In another trial in mice, rifampicin (100 mg/kg daily for 15 days) was found to be the most active (causing a 74% reduction in the number of mff recovered--approximately equal to that achieved with the positive control of a single dose of ivermectin at 2 microg/kg), with chloramphenicol also showing significant activity (39% reduction) . In further, in-vivo trials, at three dose levels (100, 25 or 6.25 mg/kg daily, for 15 days), all three antibiotics were tested against adult Brugia pahangi in the peritoneal cavities of jirds . None of the antibiotics produced a significant reduction in the numbers of live worms recovered, although a marginal effect was observed in eight of the nine antibiotic-treated groups . A further extended trial with rifampicin and oxytetracycline resulted in 43% and 38% reductions in worm recoveries, respectively (not statistically significant but consistent with a marginal effect); some of these worms appeared less motile and qualitatively in poor condition compared with those recovered from untreated jirds . Ultrastructural studies of these treated worms revealed that virtually all of the endosymbiont bacteria had been cleared from the parasite tissues . The tissues of the adult worms appeared to be largely intact but with a granulomatous response of host cells adhering to some specimens . However, developing uterine forms appeared to be abnormal and extensively damaged, showing an abrogation of embryogenesis . In contrast, worms recovered from control animals contained large numbers of Wolbachia, had no adherent host cells, and showed normal ultrastructure; the female worms exhibited a full range of intra-uterine developing stages from eggs to stretched mff . It is likely that the activity of these antibiotics against the endosymbiont Wolbachia causes the observed antifilarial activity, although some direct effect of each drug on filarial viability cannot be ruled out.

Int J Syst Evol Microbiol, 2001 Jan, 51(Pt 1), 55 - 9
Arcanobacterium pluranimalium sp . nov., isolated from porpoise and deer; Lawson PA et al.; Two strains of a previously undescribed Arcanobacterium-like bacterium were isolated from a dead harbour porpoise and a dead sallow deer . Biochemical testing and PAGE analysis of whole-cell proteins indicated that the strains were phenotypically closely related to each other and distinct from previously described Actinomyces and Arcanobacterium species . Comparative 16S rRNA gene sequencing studies showed the bacterium to be a hitherto unknown subline within the genus Arcanobacterium . Based on phylogenetic and phenotypic evidence, it is proposed that the unknown bacterium be classified as Arcanobacterium pluranimalium sp . nov . The type strain of Arcanobacterium pluranimalium is CCUG 42575T (= CIP 106442T).

Int J Syst Evol Microbiol, 2001 Jan, 51(Pt 1), 151 - 6
Actinomyces marimammalium sp . nov., from marine mammals; Hoyles L et al.; Three strains of a previously undescribed Actinomyces-like bacterium were isolated from samples taken from two dead seals and a porpoise . Biochemical testing and PAGE analysis of whole-cell proteins indicated the strains were phenotypically similar to each other but different from previously described Actinomyces and Arcanobacterium species . Comparative 16S rRNA gene sequencing studies showed the organisms from marine animals were genetically closely related and represent a hitherto unknown subline within the genus Actinomyces (sequence divergence values > 6% with recognized species) . Based on phylogenetic and phenotypic evidence it is proposed that the unknown bacterium from the seals and a porpoise should be classified as Actinomyces marimammalium sp . nov . The type strain is CCUG 41710T.

Int J Syst Evol Microbiol, 2001 Jan, 51(Pt 1), 133 - 40
Desulfosporosinus meridiei sp . nov., a spore-forming sulfate-reducing bacterium isolated from gasolene-contaminated groundwater; Robertson WJ et al.; Eight strains of spore-forming, sulfate-reducing bacteria, isolated from groundwater contaminated with motor fuel {mostly benzene, toluene ethylbenzene and xylene (BTEX) compounds} in sandy soil near Perth, Australia, were closely related to Desulfosporosinus (previously Desulfotomaculum) orientis DSM 765T (95.3-97.3% 16S rDNA sequence similarity) . Whole-cell fatty acids were dominated by even-carbon, straight-chain saturated and mono-unsaturated fatty acids, in particular 16:0, 16:1cis9, 14:0 and 18:1cis11 . The strains grew at temperatures between 4 and 42 degrees C and in medium containing up to 4% NaCl . The eight strains clustered into two main groups based on phylogeny, randomly amplified polymorphic DNA (RAPD)-PCR patterns and nutritional characteristics . Representatives of the two groups, strain S5 (group A) and strain S10T (group B) had 81% DNA-DNA homology with each other and therefore should be accommodated in the same species . Strain S10T had less than 38% homology with Desulfosporosinus orientis DSM 765T, the most closely phylogenetically related type strain available . The new strains were distinguished from Desulfosporosinus orientis DSM 765T by different banding patterns in a RAPD-PCR, and phenotypically by their inability to utilize fumarate as a carbon and energy source with sulfate as the electron acceptor and by their lower tolerance to NaCl . The DNA G+C contents were 46.8 and 46.9 mol% for strains S5 and S10T, respectively (Desulfosporosinus orientis DSM 765T 45.9 mol%) . It is proposed that these new strains be placed in a new species of the genus Desulfosporosinus . The name Desulfosporosinus meridiei is proposed, with strain S10T as the type strain (= DSM 13257T = NCIMB 13706T).

Biosci Biotechnol Biochem, 2000 Dec, 64(12), 2668 - 74
A cold acclimation protein with refolding activity on frozen denatured enzymes; Kawahara H et al.; We found that a cold acclimation protein from an ice-nucleating bacterium, Patoea ananas KUIN-3, has refolding activity on frozen denatured protein . Based on a SDS-PAGE analysis, we confirmed that the cold shock-treated cells of strain KUIN-3 could produce some cold acclimation proteins that inhibit their syntheses by the addition of chloramphenicol during the cold acclimation . Among such proteins, Hsc25 had refolding activity similar to GroELS . Hsc25 was purified to apparent homogeneity by (NH4)2SO4 precipitation and some chromatographies . The purified Hsc25 was composed of 8 subunits of 25,000 each with a molecular mass of 200,000 and had refolding activity against denatured enzymes, which were denatured by heat-treatment at 100 degrees C, cryopreservation at -20 degrees C, or guanidine hydrochloride, in a manner similar to GroELS . The N-terminal sequence of Hsc25 was Met-Arg-Ala-Ser-Thr-Tyr-His-Ala-Ala-Arg- . Furthermore, Hsc25 had a high level of activity at low temperature (12 degrees C) . Also, the dissociation constants, KD (M) as the binding specificity for enolase, mutarotase, isocitrate dehydrogenase, and lactate dehydrogenase were 1.82x10(-10), 4.35x10(-9), 8.98x10(-12), and 3.05x10(-11), respectively . The affinity of Hsc25 for frozen danatured enzymes was higher than the affinity for heat denatured enzymes when compared with the affinity of GroEL . These results are the first report on the characterization of a purified chaperon that was induced by cold acclimation.

Nature, 2001 Jan 25, 409(6819), 529 - 33
Genome sequence of enterohaemorrhagic Escherichia coli O157:H7; Perna NT et al.; The bacterium Escherichia coli O157:H7 is a worldwide threat to public health and has been implicated in many outbreaks of haemorrhagic colitis, some of which included fatalities caused by haemolytic uraemic syndrome . Close to 75,000 cases of O157:H7 infection are now estimated to occur annually in the United States . The severity of disease, the lack of effective treatment and the potential for large-scale outbreaks from contaminated food supplies have propelled intensive research on the pathogenesis and detection of E . coli O157:H7 (ref . 4) . Here we have sequenced the genome of E . coli O157:H7 to identify candidate genes responsible for pathogenesis, to develop better methods of strain detection and to advance our understanding of the evolution of E . coli, through comparison with the genome of the non-pathogenic laboratory strain E . coli K-12 (ref . 5) . We find that lateral gene transfer is far more extensive than previously anticipated . In fact, 1,387 new genes encoded in strain-specific clusters of diverse sizes were found in O157:H7 . These include candidate virulence factors, alternative metabolic capacities, several prophages and other new functions--all of which could be targets for surveillance.

Vet Hum Toxicol, 2001 Feb, 43(1), 1 - 5
Glue solvent inhalation impairs host resistance to Mycobacterium bovis-induced infection in hamsters; Palermo-Neto J et al.; Industrial organic solvents present in glue are among the common used psychotropic drugs in Brazil and perhaps worldwide; but few data are available concerning the toxic effects of glue sniffing, with almost no information about immunotoxicity . This seems interesting because several drugs and environmental chemicals are recognized as potential immunotoxicants . The present study investigated the effects of forced inhalation of a toluene/n-hexane 1:1 mixture on hamster resistance to Mycobacterium bovis . Adult hamsters were divided at random into 3 equal groups . Animals of Groups E and E inhaled the mixture of toluene/n-hexane twice daily for 37 d . Group C was placed for the same period of time in identical chambers free of solvents . Two days after the beginning of the experiment, Groups E and C were injected ip with 0.5 ml of an activated suspension of M . bovis; Group E received the same volume of a control solution . Hamsters inhaling the toluene/n-hexane mixture (E) exhibited increased weight loss, increased scores of M . bovis colony forming units isolated from liver, lung and spleen, increased granulomatous areas in the liver, lung and spleen . Inhalation of the toluene/n-hexane mixture for 37 d also increased serum cortisol compared to control hamsters . Tuberculosis is an infection with an intracellular bacterium in which sensitivity is determined mainly by host response . The present data demonstrated impaired defense against M . bovis in hamsters inhaling a toluene/n-hexane mixture for 37 d . Since macrophages are the architectural and functional units of the granulomas in tuberculosis, and no data were found about glue solvent effects on cellular immunity, the present data suggest an indirect effect of glue solvents on macrophage/lymphocyte activity via stress induction and central nervous system stimulation of hormonal (ACTH/cortisol) secretion and/or autonomic nervous system activity.

J Am Vet Med Assoc, 2001 Feb 1, 218(3), 367 - 75
Effect of vaccination on experimental infection with Bordetella bronchiseptica in dogs; Ellis JA et al.; OBJECTIVE: To determine comparative efficacy of vaccines administered IM and intranasally, used alone or sequentially, to protect puppies from infection with Bordetella bronchiseptica and determine whether systemic or mucosal antibody response correlated with protection . DESIGN: Randomized controlled trial . ANIMALS: 50 specific-pathogen-free Beagle puppies . PROCEDURE: In 2 replicates of 25 dogs each, 14-week-old puppies that were vaccinated against canine distemper virus and parvovirus were vaccinated against B bronchiseptica via intranasal, IM, intranasal-IM, or IM-intranasal administration or were unvaccinated controls . Puppies were challenge exposed via aerosol administration of B bronchiseptica 2 weeks after final vaccination . Clinical variables and systemic and mucosal antibody responses were monitored for 10 days after challenge exposure . Puppies in replicate 1 were necropsied for histologic and immunohistochemical studies . RESULTS: Control puppies that were seronegative before challenge exposure developed paroxysmal coughing, signs of depression, anorexia, and fever . Vaccinated puppies (either vaccine) that were seronegative before challenge exposure had fewer clinical signs . Puppies that received both vaccines had the least severe clinical signs and fewest lesions in the respiratory tract . Vaccinated dogs had significantly higher concentrations of B bronchiseptica-reactive antibodies in serum saliva before and after challenge . Antibody concentrations were negatively correlated with bacterial growth in nasal cavity and pharyngeal samples after challenge exposure . CONCLUSIONS AND CLINICAL RELEVANCE: Parenterally and intranasally administered vaccines containing B bronchiseptica may provide substantial protection from clinical signs of respiratory tract disease associated with infection by this bacterium . Administration of both types of vaccines in sequence afforded the greatest degree of protection against disease.

Arch Immunol Ther Exp (Warsz), 2000, 48(6), 521 - 7
Mechanisms of Mycobacterium avium pathogenesis; Bermudez LE et al.; Infections caused by Mycobacterium avium are common in AIDS patients and patients with chronic lung diseases . The bacterium can be acquired both through the intestinal route and respiratory route . M . avium is capable of invading mucosal epithelial cells and translocating across the mucosa . The bacterium can infect macrophages, interfering with several functions of the host cell . The host defense against M . avium is primarily dependent on CD4+ T lymphocytes and natural killer cells . Activated macrophages can inhibit or kill intracellular bacteria by mechanisms that are currently unknown, but M . avium can invade resting macrophages and suppress key aspects of their function by triggering the release of transforming growth factor beta and interleukin 10 . Co-infection with HIV-1 appears to be mutually beneficial, with both organisms growing faster.

J Pharm Pharmacol, 2000 Dec, 52(12), 1541 - 6
Recombinant human lactoferrin is effective in the treatment of Helicobacter felis-infected mice; Dial EJ et al.; Recombinant human lactoferrin possesses in-vitro antibiotic and anti-inflammatory activity similar to the native form . It was tested for in-vivo activity in mice infected with the gastritis-inducing bacterium Helicobacter felis . A two-week course of treatment with lactoferrin was sufficient to partially reverse both infection-induced gastritis and the infection rate, and fully reverse gastric surface hydrophobicity changes . A comparison of lactoferrin with amoxicillin and standard triple therapy revealed no differences in infection rate . These results show that recombinant human lactoferrin is effective in a mouse model of Helicobacter infection, and support further testing of this promising agent for this application.

Avian Dis, 2000 Oct-Dec, 44(4), 957 - 62
Outer membrane proteins for serologic detection of Ornithobacterium rhinotracheale infection in turkeys; Lopes V et al.; Ornithobacterium rhinotracheale (ORT) is a bacterium responsible for a respiratory disease in turkeys and chickens and has been identified as one of the emerging respiratory bacterial pathogens . The clinical signs and lesions caused by ORT are very similar to those caused by other respiratory infectious agents; therefore, an accurate diagnostic test is necessary to identify the infection . In this study, we have investigated the use of outer membrane proteins of ORT in an indirect enzyme-linked immunosorbent assay (ELISA) to detect the exposure to ORT infection . Outer membrane proteins of ORT were extracted and used as an antigen in ELISA to detect infection in turkeys exposed to different serotypes of ORT . The ELISA results were compared with the conventional serum plate agglutination test . The agglutination test detected specific antibodies for ORT in 65% of experimentally infected turkeys during the first 2 wk of infection . The ELISA detected up to 100% of infected birds for 8 wk postinfection . The results suggest that ELISA is able to detect the exposure to ORT in later stages of the infection and this assay can be used in serologic surveillance of ORT infection for poultry in the field.

Drug Deliv, 2000 Oct-Dec, 7(4), 237 - 43
Positively charged gelatin microspheres as gastric mucoadhesive drug delivery system for eradication of H . pylori; Wang J et al.; Gastric mucoadhesive drug delivery systems are very promising for eradication of Helicobacter pylori (H . pylori), a spiral bacterium that resides in the gastric mucus layer and at the mucus-epithelial cell interface . New positively charged biodegradable microspheres were prepared using aminated gelatin by surfactant-free emulsification in olive oil, followed by a cross-linking reaction with glutaraldehyde . The amino group contents of the modified gelatin and the microspheres were determined using a 2,4,6-trinitrobenzenesulfonic acid method . With the increase of glutaraldehyde concentration, the amino group content of the microspheres decreased accordingly . The influence of glutaraldehyde concentration, cross-linking reaction time, drug-loading patterns, and type of release media on the in vitro release characteristics of amoxicillin from the microspheres was investigated . Amoxicillin release rate from the modified gelatin microspheres was significantly reduced compared with that from gelatin microspheres . Furthermore, the release was decreased with the increase of glutaraldehyde concentration and/or cross-linking time . On the other hand, a faster release was observed in a lower pH release medium and/or using a lower pH solution for amoxicillin loading . The gastric mucoadhesive properties of the microspheres were evaluated using RITC-labeled microspheres in an isolated rat stomach . The gastric mucoadhesion of the modified gelatin microspheres was markedly improved compared with that of gelatin microspheres . The modified gelatin microsphere proves to be a possible candidate delivery system for the effective eradication of H . pylori.

Arch Microbiol, 2000 Dec, 174(6), 448 - 51
Stable sulfur isotope fractionation during the reduction of thiosulfate by Dethiosulfovibrio russensis; Surkov AV et al.; Stable sulfur isotope fractionation was investigated during reduction of thiosulfate by growing batch cultures of Dethiosulfovibrio russensis at a cell-specific reduction rate of 2.4 +/- 0.72 fmol cell(-1) d(-1) (28 degrees C) . Citrate was used as carbon and energy source . The hydrogen sulfide produced by this sulfur- and thiosulfate-reducing bacterium was depleted in 34S by 11% compared to total thiosulfate sulfur, in agreement with previous results observed for sulfate-reducing bacteria . This indicates the operation of a similar pathway for thiosulfate reduction in these phylogenetically different bacteria.

Biosci Biotechnol Biochem, 2000 Nov, 64(11), 2352 - 9
Characterization of O-acetyl-L-serine sulfhydrylase purified from an alkaliphilic bacterium; Sugihara Y et al.; O-Acetyl-L-serine sulfhydrylase (EC 4.2.99.8) activity was shown to be very high compared with O-acetyl-L-homoserine sulfhydrylase (EC 4.2.99.10) activity and L-cystathionine cleaving activities, in an extract of cells of an alkaliphilic bacterium grown in a synthetic medium . The synthesis of the first enzyme was repressed by approximately 55% by both L-cystine and L-djenkolic acid added to the medium at a concentration of 0.5 mM, but L-methionine (1 mM) and S-adenosyl-L-methionine (0.5 mM) affected it to lesser extents . Its enzyme activity was inhibited by 25% and 12% by methionine (10 mM) and S-adenosylmethionine (5 mM), respectively . The enzyme was purified from the extract through ammonium sulfate fractionation, heat treatment, and chromatography on columns of DEAE-cellulose, Sephacryl S-300, and Octyl Sepharose CL-4B with a recovery of 21% . Polyacrylamide gel electrophoresis with sodium dodecylsulfate of the preparation obtained finally showed its homogeneity and the molecular mass of 37,000 Da for dissociated subunits . Gel filtration of the enzyme on a Sephacryl S-300 column showed an approximate molecular mass of 72,000 Da, suggesting that the enzyme was comprised of two identical subunits . The enzyme catalyzed the beta-replacement reaction with O-acetylserine as a substrate, and showed no reactivity to other O-substituted amino acids tested . The reaction proceeded best at 40 degrees C (when tested at pH 7.5), and at pH 6.5 (at 40 degrees C) . The enzyme kept 90% its activity after incubation at 65 degrees C (at pH 7.5) for 30 min, and more than 90% after 30 min incubation at pHs 7-12 at 30 degrees C . The enzyme had a Km of 4 mM for O-acetyl-L-serine and a Vmax of 37.0 micromol/min/mg of protein, a very low value compared with those of other organisms . However, the content of the enzyme in the extract was calculated to be approximately 3.5% total protein . Sensitivity of the enzyme to carbonyl reagents was very low, although it was shown to have pyridoxal 5'-phosphate as a cofactor by examination of its absorption spectrum . Sulfhydryl reagents tested showed no inhibition . The novelty of this enzyme among analogous sulfhydrylases purified from other organisms was discussed.

Environ Microbiol, 1999 Oct, 1(5), 415 - 20
Anaerobic degradation of naphthalene by a pure culture of a novel type of marine sulphate-reducing bacterium; Galushko A et al.; Incubation of marine sediment in anoxic, sulphate-rich medium in the presence of naphthalene resulted in the enrichment of sulphate-reducing bacteria . Pure cultures with short, oval cells (1.3 by 1.3-1.9 microm) were isolated that grew with naphthalene as the only organic carbon source and electron donor for sulphate reduction to sulphide . One strain, NaphS2, was characterized . It affiliated with completely oxidizing sulphate-reducing bacteria of the delta-subclass of the Proteobacteria, as revealed by 16S rRNA sequence analysis . 2-Naphthoate, benzoate, pyruvate and acetate were used in addition to naphthalene . Quantification of substrate consumption, sulphide formation and formed cell mass revealed that naphthalene was completely oxidized with sulphate as the electron acceptor.

Environ Microbiol, 1999 Jun, 1(3), 213 - 21
Grazing of the copepod Diaptomus connexus on purple sulphur bacteria in a meromictic salt lake; Overmann J et al.; A meromictic lake ecosystem (Mahoney Lake, BC, Canada) was investigated to elucidate the significance of chemocline bacteria in the total carbon cycle under natural conditions . In this lake, primary production by oxygenic phototrophs was insufficient to support the observed net secondary production of the calanoid copepod Diaptomus connexus and the rotifer Brachionus plicatilis, indicating the presence of additional food sources for consumers . Mahoney Lake harbours the densest population of phototrophic sulphur bacteria ever reported in a natural body of water . This layer is located at the interface between oxic and anoxic water layers and is dominated by the purple sulphur bacterium Amoebobacter purpureus . The transfer rates of A . purpureus carbon to D . connexus determined in stratified mesocosms were very low (0.71 ngC copepod(-1) day(-1)) and accounted for only 0.6% of the observed net biomass increase in the zooplankter . Stable stratification within the mesocosms prevented an upwelling of A . purpureus into the oxic part . However, measurements of carbon fluxes, infrared fluorescence microscopy and stable carbon analysis provided cumulative evidence that, under in situ conditions, the cell carbon of purple sulphur bacteria indeed enters the aerobic food chain via the grazing activity of D . connexus . Based on a two-source isotopic mixing model, A . purpureus represents at least 75-85% of the diet of D . connexus . Autumnal upwelling into oxic water layers and aggregation of A . purpureus cells appear to be the main factors determining the high carbon flux from purple sulphur bacteria to zooplankton under natural conditions, and most probably also play a key role in other aquatic ecosystems . Through this pathway, over 53% of the reduced organic matter of purple sulphur bacteria trapped in anoxic bottom waters is returned to the oxic realm.

Cell Microbiol, 2000 Dec, 2(6), 561 - 8
Mycobacterium avium enters intestinal epithelial cells through the apical membrane, but not by the basolateral surface, activates small GTPase Rho and, once within epithelial cells, expresses an invasive phenotype; Sangari FJ et al.; Mycobacterium avium is a common pathogen in AIDS patients that is primarily (but not exclusively) acquired through the gastrointestinal tract, leading to the development of bacteraemia and disseminated disease . To cause infection through the gut, binding and invasion of the intestinal epithelial barrier are required . To characterize this process further, we determined the cell surface(s) (basolateral vs . apical membrane) that M . avium interacts with in intestinal mucosal cells in vitro . The level of binding and invasion of both HT-29 and Caco-2 intestinal cell monolayers by M . avium were similar when the assay was performed with control medium in the presence of Ca2+ (when only the apical surface was exposed), with Ca2+-depleted medium or with Ca2+-depleted medium + 1 mM EGTA (exposure of both apical and basolateral membranes), suggesting that the bacterium enters the apical surface of the epithelial lining . These observations were confirmed by assays in a transwell system and by using fluorescent microscopy . Real-time video microscopy showed that M . avium entry was not associated with membrane ruffling and the use of pharmacological inhibitors of the small GTPases demonstrated that M . avium invasion is dependent on the activation of the small GTPases Rho, but not on Rac or Cdc42 . Passage of M . avium through HT-29 cells led to a phenotypic change (intracellular growth; IG) that was associated with a significantly greater (between five- and ninefold) ability to bind to and invade new monolayers of epithelial cells or macrophages when compared with the invasion by M . avium grown on agar (extracellular growth; EG) . IG phenotype invasion of HT-29 cells also takes place only by the apical surface . M . avium enters intestinal epithelial cells by the apical surface and, once within the cells, changes phenotype, becoming more invasive towards both macrophages and other epithelial cells.

Cell Microbiol, 1999 Jul, 1(1), 51 - 60
Signalling and cellular specificity of airway nitric oxide production in pertussis; Flak TA et al.; Bordetella pertussis, the aetiological agent of whooping cough (pertussis), causes selective destruction of ciliated cells of the human airway mucosa . In a hamster tracheal organ culture model, B . pertussis causes identical cytopathology as does tracheal cytotoxin (TCT), a glycopeptide released by the bacterium . The damage caused by B . pertussis or TCT has been shown to be mediated via nitric oxide (NO*) . Using immunofluorescence detection of the cytokine-inducible NO synthase (iNOS; NOS type II), we determined that B . pertussis induced epithelial NO* production exclusively within non-ciliated cells . This epithelial iNOS activation could be reproduced by the combination of TCT and endotoxin . However, neither TCT alone nor endotoxin alone was capable of inducing epithelial iNOS . This result mirrors the synergistic activity of TCT and endotoxin exhibited in monolayer cultures of tracheal epithelial cells . Therefore, TCT and endotoxin are both important virulence factors of B . pertussis, combining synergistically to cause the specific epithelial pathology of pertussis.

Cancer Lett, 2001 Mar 26, 164(2), 127 - 33
Helicobacter pylori decreases gastric mucosal glutathione; Shirin H et al.; Activation of oxidative stress pathways may contribute to gastric epithelial damage and mutagenesis caused by Helicobacter pylori . We measured the effect of H . pylori on the concentrations of reduced glutathione (GSH), an important endogenous defense against oxidant damage, in gastric epithelial cells in vivo and in vitro . GSH concentrations were significantly lower in gastric biopsies from 19 H . pylori-infected patients than 38 normal controls, and correlated inversely with inflammatory cell numbers . In vitro, H . pylori initially increased GSH levels in AGS cells, but subsequently depleted intracellular GSH stores completely after 24 h . No GSH was detected in H . pylori . Our data suggest that diminished GSH levels with H . pylori colonization of the gastric mucosa may be due to a direct effect of the bacterium as well as through the associated inflammatory response.

Infect Immun, 2001 Mar, 69(3), 1967 - 70
Neutralization of Shiga toxins Stx1, Stx2c, and Stx2e by recombinant bacteria expressing mimics of globotriose and globotetraose; Paton AW et al.; Strains of Escherichia coli producing Shiga toxins Stx1, Stx2, Stx2c, and Stx2d cause gastrointestinal disease and the hemolytic-uremic syndrome in humans . We have recently constructed a recombinant bacterium which displays globotriose (the receptor for these toxins) on its surface and adsorbs and neutralizes these Shiga toxins with very high efficiency . This agent has great potential for the treatment of humans with such infections . E . coli strains which cause edema disease in pigs produce a variant toxin, Stx2e, which has a different receptor specificity from that for the other members of the Stx family . We have now modified the globotriose-expressing bacterium such that it expresses globotetraose (the preferred receptor for Stx2e) by introducing additional genes encoding a N-acetylgalactosamine transferase and a UDP-N-acetylgalactosamine-4-epimerase . This bacterium had a reduced capacity to neutralize Stx1 and Stx2c in vitro, but remarkably, its capacity to bind Stx2e was similar to that of the globotriose-expressing construct; both constructs neutralized 98.4% of the cytotoxicity in lysates of E . coli JM109 expressing cloned stx2e . These data suggest that either globotriose- or globotetraose-expressing constructs may be suitable for treatment and/or prevention of edema disease in pigs.

Infect Immun, 2001 Mar, 69(3), 1389 - 93
Oral administration of formaldehyde-killed recombinant bacteria expressing a mimic of the Shiga toxin receptor protects mice from fatal challenge with Shiga-toxigenic Escherichia coli; Paton JC et al.; Gastrointestinal disease caused by Shiga toxin-producing Escherichia coli (STEC) is frequently complicated by life-threatening toxin-induced systemic sequelae, including the hemolytic uremic syndrome . We previously constructed a recombinant bacterium displaying a Shiga toxin receptor mimic on its surface which neutralized Shiga toxins with very high efficiency . Moreover, oral administration of the live bacterium completely protected mice from challenge with virulent STEC . In this study, we investigated the protective capacity of formaldehyde-killed receptor mimic bacteria, as these are likely to be safer for administration to humans . The killed bacteria completely protected STEC-challenged mice when administered three times daily; incomplete protection was achieved using two doses per day . Commencement of therapy could be delayed for up to 48 h after challenge without diminishing protection, depending on the virulence of the challenge strain . Thus, administration of this agent early in the course of human STEC disease may prevent progression to life-threatening complications.

Ann Intern Med, 2001 Jan 16, 134(2), 115 - 9
Tropheryma whippelii DNA is rare in the intestinal mucosa of patients without other evidence of Whipple disease; Maiwald M et al.; BACKGROUND: Little is known about the pathogenesis of Whipple disease, the reservoirs of Tropheryma whippelii, and the proportion of persons harboring the bacterium without "classic" intestinal abnormalities . OBJECTIVE: To assess the presence of T . whippelii in patients undergoing upper endoscopy for a variety of indications . DESIGN: Prospective and routine diagnostic examination of patients . SETTING: Three academic medical centers in California; Minnesota; and Heidelberg, Germany . PATIENTS: 342 patients undergoing endoscopy for evaluation of dyspepsia or possible peptic ulcer (group A, 173 patients), malabsorption (group B, 37 patients), or clinical suspicion of Whipple disease (group C, 132 patients) . MEASUREMENTS: Small-intestinal biopsy specimens were tested by polymerase chain reaction for T . whippelii DNA and examined for histopathologic abnormalities . RESULTS: All patients with negative histologic findings also had negative results for T . whippelii DNA . CONCLUSIONS: T . whippelii occurs only rarely in intestinal mucosa that lacks histopathologic evidence of Whipple disease . The human small intestinal mucosa is an unlikely reservoir for this organism.

Pediatr Infect Dis J, 2001 Jan, 20(1), 84 - 5
Turicella otitidis mastoiditis in a healthy child; Dana A et al.; Turicella otitidis, a coryneform bacterium, has been associated with acute otitis media . A 5-year-old girl developed acute mastoiditis . Turicella was isolated from the right and left middle ear fluid.

Acta Crystallogr D Biol Crystallogr, 2001 Feb, 57(Pt 2), 314 - 6
Purification, crystallization and preliminary X-ray analysis of the Escherichia coli glucose-1-phosphatase; Jia Z et al.; Encoded by the agp gene, Escherichia coli glucose-1-phosphatase hydrolyzes glucose-1-phosphate in the periplasmic space of the bacterium . It is a potential drug-design target because inositol phosphatases have been identified as important virulence determinants in several human and animal pathogens . The enzyme was isolated and purified to homogeneity from a strain of E . coli CU1867 (an appA-deficient mutant) . Crystals were obtained overnight by the equilibrium vapour-diffusion method from a solution containing 10 mg ml(-1) enzyme, 1.2 M ammonium sulfate and 25% polyethylene glycol monomethyl ether 5000 in 0.1 M MES at pH 6.5 . The crystals belong to space group R3, with unit-cell parameters a = b = 156.0, c = 92.2 A . The diffraction limit was 2.6 A at a rotating-anode X-ray source; a 2.7 A resolution data set has been collected using light mineral oil as a cryoprotectant . The data set was 95.2% complete, with an R(sym) of 0.058 . There were two monomers of glucose-1-phosphatase in the asymmetric unit, which correspond to a V(M) of 2.36 A Da(-1) and 47.5% solvent content . Self-rotation analysis unambiguously shows a twofold non-crystallographic symmetry.

Curr Opin Microbiol, 2001 Feb, 4(1), 21 - 7
Molecular basis for the peripheral nerve predilection of Mycobacterium leprae; Rambukkana A; Mycobacterium leprae, the causative organism of leprosy, has a unique predilection for Schwann cells, the glial cells of the peripheral nervous system . M . leprae invasion of Schwann cells leads to the neurological damage that underlies the sensory motor loss and subsequent deformity and disability associated with this disease . Recent studies have begun to elucidate the early events of M . leprae infection of Schwann cells on a molecular level, and the host and bacterial factors that determine the neural predilection of this bacterium . These advances have now provided novel insights into the mechanisms of bacterial interactions with host cells.

Biochem Soc Trans, 2000 Dec, 28(6), 943 - 5
Biosynthesis of fatty acids in the docosahexaenoic acid-producing bacterium Moritella marina strain MP-1; Morita N et al.; We have isolated the fatty acid biosynthetic (fab) gene cluster taking part in the synthesis of middle-chain fatty acids and a genomic segment which was homologous with the eicosapentaenoic acid-biosynthetic gene cluster from the docosahexaenoic acid (DHA)-producing bacterium Moritella marina strain MP-1 . This segment was presumed to include the DHA-biosynthetic gene cluster of M . marina strain MP-1 . When M . marina strain MP-1 was cultured in medium containing cerulenin, a fatty acid synthesis inhibitor, decreases in levels of middle-chain fatty acids and remarkable increases in levels of DHA were observed . These results suggest that the synthesis of middle-chain fatty acids works independently of the synthesis of DHA.

Biochemistry, 2001 Feb 6, 40(5), 1317 - 24
Nonaheme cytochrome c, a new physiological electron acceptor for {Ni,Fe} hydrogenase in the sulfate-reducing bacterium Desulfovibrio desulfuricans Essex: primary sequence, molecular parameters, and redox properties.; Fritz G et al.; A nonaheme cytochrome c was purified to homogeneity from the soluble and the membrane fractions of the sulfate-reducing bacterium Desulfovibrio desulfuricans Essex . The gene encoding for the protein was cloned and sequenced . The primary structure of the multiheme protein was highly homologous to that of the nonaheme cytochrome c from D . desulfuricans ATCC 27774 and to that of the 16-heme HmcA protein from Desulfovibrio vulgaris Hildenborough . The analysis of the sequence downstream of the gene encoding for the nonaheme cytochrome c from D . desulfuricans Essex revealed an open reading frame encoding for an HmcB homologue . This operon structure indicated the presence of an Hmc complex in D . desulfuricans Essex, with the nonaheme cytochrome c replacing the 16-heme HmcA protein found in D . vulgaris . The molecular and spectroscopic parameters of nonaheme cytochrome c from D . desulfuricans Essex in the oxidized and reduced states were analyzed . Upon reduction, the pI of the protein changed significantly from 8.25 to 5.0 when going from the Fe(III) to the Fe(II) state . Such redox-induced changes in pI have not been reported for cytochromes thus far; most likely they are the result of a conformational rearrangement of the protein structure, which was confirmed by CD spectroscopy . The reactivity of the nonaheme cytochrome c toward {Ni,Fe} hydrogenase was compared with that of the tetraheme cytochrome c(3); both the cytochrome c(3) and the periplasmic {Ni,Fe} hydrogenase originated from D . desulfuricans Essex . The nonaheme protein displayed an affinity and reactivity toward {Ni,Fe} hydrogenase {K(M) = 20.5 +/- 0.9 microM; v(max) = 660 +/- 20 nmol of reduced cytochrome min(-1) (nmol of hydrogenase)(-1)} similar to that of cytochrome c(3) {K(M) = 12.6 +/- 0.7 microM; v(max) = 790 +/- 30 nmol of reduced cytochrome min(-1) (nmol of hydrogenase)(-1)} . This shows that nonaheme cytochrome c is a competent physiological electron acceptor for {Ni,Fe} hydrogenase.

Acc Chem Res, 2001 Jan, 34(1), 40 - 8
Mimicking photosynthetic solar energy transduction; Gust D et al.; Increased understanding of photosynthetic energy conversion and advances in chemical synthesis and instrumentation have made it possible to create artificial nanoscale devices and semibiological hybrids that carry out many of the functions of the natural process . Artificial light-harvesting antennas can be synthesized and linked to artificial reaction centers that convert excitation energy to chemical potential in the form of long-lived charge separation . Artificial reaction centers can form the basis for molecular-level optoelectronic devices . In addition, they may be incorporated into the lipid bilayer membranes of artificial vesicles, where they function as components of light-driven proton pumps that generate transmembrane proton motive force . The proton gradient may be used to synthesize adenosine triphosphate via an ATP synthase enzyme . The overall energy transduction process in the liposomal system mimics the solar energy conversion system of a photosynthetic bacterium . The results of this research illustrate the advantages of designing functional nanoscale devices based on biological paradigms.

Am J Med, 2001 Jan 8, 110(1A), 50S - 54S
Nonsteroidal anti-inflammatory drug gastropathy and Helicobacter pylori: the search for an improbable consensus; Lazzaroni M et al.; Nonsteroidal anti-inflammatory drugs (NSAIDs) and Helicobacter pylori are known to share a number of pathogenic mechanisms, but there is no evidence to show a significant synergistic action between these two risk factors . Studies to assess possible interactions in the pathogenesis of dyspepsia and upper gastrointestinal mucosal lesions have differed in their endpoints, the definition of dyspepsia, and the regimens used for eradication of H . pylori . However, some conclusions may be drawn from the results of clinical trials . As far as dyspepsia is concerned, an association between NSAID dyspepsia and infection with H . pylori, seems likely, but it is difficult to make sense of the discrepant data that are currently available . On the contrary, neither short- nor long-term NSAID administration presents a definite major risk of gastric and duodenal injury or, above all, of ulcer-related complications (bleeding or perforation) in H . pylori-positive patients . Based on these considerations, what recommendations can be made with regard to H . pylori eradication in patients requiring treatment with NSAIDs? H . pylori and anti-inflammatory drugs are probably independent causes of gastric and duodenal damage . Patients taking NSAIDs who are found to have gastric or duodenal ulcers should, therefore, be tested for the bacterium and specifically treated, because H . pylori and NSAID-induced ulcers may be macroscopically indistinguishable . Whether asymptomatic patients taking NSAIDs should be tested and treated for H . pylori infection is still a matter of debate.

FEMS Microbiol Lett, 2001 Jan 15, 194(2), 215 - 20
Biosynthesis of poly-beta-hydroxybutyrate (PHB) is controlled by CydR (Fnr) in the obligate aerobe Azotobacter vinelandii; Wu G et al.; CydR is an Fnr-like protein in the obligatory aerobic nitrogen-fixing bacterium Azotobacter vinelandii . The cydR mutant overproduces the cytochrome bd terminal oxidase . Using two-dimensional polyacrylamide gel electrophoresis, we showed that beta-ketothiolase and acetoacetyl-CoA reductase were also overexpressed in the cydR mutant . Fumarase C and a coenzyme A transferase, possibly succinyl-SCoA transferase, were decreased in this mutant . Enzyme assays confirmed the elevated beta-ketothiolase and acetoacetyl-CoA reductase activities in this mutant . The cydR mutant accumulated poly-beta-hydroxybutyrate throughout the exponential growth phase, unlike the wild-type strain that only accumulated poly-beta-hydroxybutyrate during stationary phase . The results demonstrate that CydR controls poly-beta-hydroxybutyrate synthesis in A . vinelandii.

Anal Biochem, 2001 Feb 15, 289(2), 147 - 56
Liquid chromatography-electrospray mass spectrometry of tunicamycin-type antibiotics; Tsvetanova BC et al.; Several Streptomyces and Clavibacter species produce a family of tunicamycin-like antibiotics (tunicamycins, streptovirudins, corynetoxins, etc.) that inhibit the polyprenol-P:N-acetylhexosamine-1-P translocase family, thus blocking both bacterial cell wall biosynthesis and eukaryotic protein N-glycosylation . The mechanisms of biosynthesis and resistance to these toxins by the producing bacteria are largely unknown . Electrospray ionization (ESI) and matrix-assisted laser desorption ionization (MALDI) mass spectrometric techniques are described that structurally assign tunicamycin N-acylated variants in the picomolar range . A voltage gradient across the ESI inlet port was used to generate fragmentation ions that were structurally diagnostic for the tunicamycins . The application of in-line reversed-phase high-performance liquid chromatography-electrospray MS (LC-ESI-MS) resulted in the identification of eight new tunicamycins . Based on these structural assignments a revised nomenclature for tunicamycins is proposed . Application of the LC-ESI-MS methodology to culture supernatants and cellular extracts of the tunicamycin-producing bacterium, Streptomyces lysosuperificus, confirmed tunicamycin production and showed it to be growth-temperature dependent, but did not detect corynetoxins production in culture by phage-infected Clavibacter toxicus .

J Immunol, 2001 Feb 1, 166(3), 1855 - 62
Outer membrane protein-specific monoclonal antibodies protect SCID mice from fatal infection by the obligate intracellular bacterial pathogen Ehrlichia chaffeensis; Li JS et al.; Previous studies of Ehrlichia chaffeensis infection in the mouse have demonstrated that passive transfer of polyclonal Abs from resistant immunocompetent mice to susceptible SCID mice ameliorated infection and disease, even when Abs were administered during established infection . To identify particular Abs that could mediate bacterial clearance in vivo, E . chaffeensis-specific mAbs were generated and administered to infected SCID mice . Bacterial infection in the livers was significantly lowered after administration of either of two Abs of different isotypes (IgG2a and IgG3) . Moreover, repeated administration of one Ab (Ec56.5; IgG2a) rescued mice from an otherwise lethal infection for at least 5 wk . Both protective Abs recognized the E . chaffeensis major outer membrane protein (OMP)-1g . Further studies revealed that both Abs recognized closely related epitopes within the amino terminus of the first hypervariable region of OMP-1g . Analyses of human sera showed that E . chaffeensis-infected patients also generated serological responses to OMP-1g hypervariable region 1, indicating that humans and mice recognize identical or closely related epitopes . These studies demonstrate that OMP-specific mAbs can mediate bacterial elimination in SCID mice, and indicate that Abs, in the absence of cell-mediated immunity, can play a significant role in host defense during infection by this obligate intracellular bacterium.

J Bacteriol, 2001 Mar, 183(5), 1780 - 3
Role for draTG and rnf genes in reduction of 2,4-dinitrophenol by Rhodobacter capsulatus; Saez LP et al.; The phototrophic bacterium Rhodobacter capsulatus is able to reduce 2,4-dinitrophenol (DNP) to 2-amino-4-nitrophenol enzymatically and thus can grow in the presence of this uncoupler . DNP reduction was switched off by glutamine or ammonium, but this short-term regulation did not take place in a draTG deletion mutant . Nevertheless, the target of DraTG does not seem to be the nitrophenol reductase itself since the ammonium shock did not inactivate the enzyme . In addition to this short-term regulation, ammonium or glutamine repressed the DNP reduction system . Mutants of R . capsulatus affected in ntrC or rpoN exhibited a 10-fold decrease in nitroreductase activity in vitro but almost no DNP activity in vivo . In addition, mutants affected in rnfA or rnfC, which are also under NtrC control and encode components involved in electron transfer to nitrogenase, were unable to metabolize DNP . These results indicate that NtrC regulates dinitrophenol reduction in R . capsulatus, either directly or indirectly, by controlling expression of the Rnf proteins . Therefore, the Rnf complex seems to supply electrons for both nitrogen fixation and DNP reduction.

J Bacteriol, 2001 Mar, 183(5), 1727 - 33
Dissimilatory sulfite reductase (desulfoviridin) of the taurine-degrading, non-sulfate-reducing bacterium Bilophila wadsworthia RZATAU contains a fused DsrB-DsrD subunit; Laue H et al.; A dissimilatory sulfite reductase (DSR) was purified from the anaerobic, taurine-degrading bacterium Bilophila wadsworthia RZATAU to apparent homogeneity . The enzyme is involved in energy conservation by reducing sulfite, which is formed during the degradation of taurine as an electron acceptor, to sulfide . According to its UV-visible absorption spectrum with maxima at 392, 410, 583, and 630 nm, the enzyme belongs to the desulfoviridin type of DSRs . The sulfite reductase was isolated as an alpha2beta)gamma(n) (n > or = 2) multimer with a native size of 285 kDa as determined by gel filtration . We have sequenced the genes encoding the alpha and beta subunits (dsrA and dsrB, respectively), which probably constitute one operon . dsrA and dsrB encode polypeptides of 49 (alpha) and 54 kDa (beta) which show significant similarities to the homologous subunits of other DSRs . The dsrB gene product of B . wadsworthia is apparently a fusion protein of dsrB and dsrD . This indicates a possible functional role of DsrD in DSR function because of its presence as a fusion protein as an integral part of the DSR holoenzyme in B . wadsworthia . A phylogenetic analysis using the available Dsr sequences revealed that B . wadsworthia grouped with its closest 16S rDNA relative Desulfovibrio desulfuricans Essex 6.

J Bacteriol, 2001 Mar, 183(5), 1694 - 706
Genetic footprinting in bacteria; Hare RS et al.; In vivo genetic footprinting was developed in the yeast Saccharomyces cerevisiae to simultaneously assess the importance of thousands of genes for the fitness of the cell under any growth condition . We have developed in vivo genetic footprinting for Escherichia coli, a model bacterium and pathogen . We further demonstrate the utility of this technology for rapidly discovering genes that affect the fitness of E . coli under a variety of growth conditions . The definitive features of this system include a conditionally regulated Tn10 transposase with relaxed sequence specificity and a conditionally regulated replicon for the vector containing the transposase and mini-Tn10 transposon with an outwardly oriented promoter . This system results in a high frequency of randomly distributed transposon insertions, eliminating the need for the selection of a population containing transposon insertions, stringent suppression of transposon mutagenesis, and few polar effects . Successful footprints have been achieved for most genes longer than 400 bp, including genes located in operons . In addition, the ability of recombinant proteins to complement mutagenized hosts has been evaluated by genetic footprinting using a bacteriophage lambda transposon delivery system.

J Bacteriol, 2001 Mar, 183(5), 1680 - 7
The hook gene (flgE) is expressed from the flgBCDEF operon in Rhodobacter sphaeroides: study of an flgE mutant; Ballado T et al.; In this work we identified the flgE gene encoding the flagellar hook protein from Rhodobacter sphaeroides . Our results show that this gene is part of a flagellar cluster that includes the genes flgB, flgC, flgD, flgE, and flgF . Two different types of mutants in the flgE gene were isolated, and both showed a Fla(-) phenotype, indicating the functionality of this sequence . Complementation studies of these mutant strains suggest that flgE is included in a single transcriptional unit that starts in flgB and ends in flgF . In agreement with this possibility, a specific transcript of approximately 3.5 kb was identified by Northern blot . This mRNA is large enough to represent the complete flgBCDEF operon . FlgE showed a relatively high proline content; in particular, a region of 12 amino acids near the N terminus, in which four prolines were identified . Cells expressing a mutant FlgE protein lacking this region showed abnormal swimming behavior, and their hooks were curved . These results suggest that this region is involved in the characteristic quaternary structure of the hook of R . sphaeroides and also imply that a straight hook, or perhaps the rigidity associated with this feature, is important for an efficient swimming behavior in this bacterium.

J Clin Microbiol, 2001 Feb, 39(2), 691 - 5
Rapid detection of mutations in the 23S rRNA gene of Helicobacter pylori that confers resistance to clarithromycin treatment to the bacterium; Matsumura M et al.; We developed a new method capable of detecting point mutations in the 23S rRNA gene of Helicobacter pylori using a LightCycler . Our method can detect a mutation in this gene in less than 1 h and can process many samples at once, thereby contributing to the selection of patients suitable for clarithromycin-based therapy.

J Clin Microbiol, 2001 Feb, 39(2), 460 - 3
Sensitive detection of Ehrlichia chaffeensis in cell culture, blood, and tick specimens by reverse transcription-PCR; Felek S et al.; Ehrlichia chaffeensis is an obligatory intracellular bacterium of monocytes and macrophages and the etiologic agent of human monocytic ehrlichiosis, an emerging zoonosis . The Lone Star tick (Amblyomma americanum) has been implicated as the primary vector of E . chaffeensis . The present study examined the sensitivity of the nested reverse transcription (RT)-PCR based on the 16S rRNA gene relative to that of the nested PCR for detection of E . chaffeensis in infected DH82 cells, experimentally infected dog peripheral blood mononuclear cells, or experimentally infected A . americanum tick samples . The RT-PCR was found to be approximately 100 times more sensitive than the PCR for detection of E . chaffeensis regardless of the nature of the specimens . Thus, this RT-PCR is useful for detection of E . chaffeensis when a high sensitivity is required . Positive results by RT-PCR also imply the presence of viable pathogens . This is the first demonstration of RNA of E . chaffeensis in infected blood and acquisition-fed male, nymphal, and larval A . americanum ticks.

Blood, 2001 Feb 1, 97(3), 812 - 4
Helicobacter pylori eradication can induce platelet recovery in idiopathic thrombocytopenic purpura; Emilia G et al.; Recent reports have suggested an association between Helicobacter pylori infection and idiopathic thrombocytopenic purpura (ITP) . The prevalence of H pylori infection and the effect of its eradication in a series of 30 ITP patients were investigated . H pylori infection has been documented in 13 patients (43.33%) by 13C urea breath test and confirmed by histologic examination . Bacterium eradication with antibiotics, obtained in 12 of 13 infected patients (92.3%), led to a complete response in 4 (33.33%) and to a partial response (platelets 90 x 10(9)/L-120 x 10(9)/L) in 2 (16.66%) . The response was maintained for a median of 8.33 months, but 1 patient relapsed 7 months after eradication . Search for H pylori infection seems appropriate in ITP patients at diagnosis . Bacterium eradication provides a new good option for a nonimmunosuppressive treatment in some ITP patients.

Appl Environ Microbiol, 2001 Feb, 67(2), 688 - 95
Cloning, sequencing, and characterization of a gene cluster involved in EDTA degradation from the bacterium BNC1; Bohuslavek J et al.; EDTA is a chelating agent, widely used in many industries . Because of its ability to mobilize heavy metals and radionuclides, it can be an environmental pollutant . The EDTA monooxygenases that initiate EDTA degradation have been purified and characterized in bacterial strains BNC1 and DSM 9103 . However, the genes encoding the enzymes have not been reported . The EDTA monooxygenase gene was cloned by probing a genomic library of strain BNC1 with a probe generated from the N-terminal amino acid sequence of the monooxygenase . Sequencing of the cloned DNA fragment revealed a gene cluster containing eight genes . Two of the genes, emoA and emoB, were expressed in Escherichia coli, and the gene products, EmoA and EmoB, were purified and characterized . Both experimental data and sequence analysis showed that EmoA is a reduced flavin mononucleotide-utilizing monooxygenase and that EmoB is an NADH:flavin mononucleotide oxidoreductase . The two-enzyme system oxidized EDTA to ethylenediaminediacetate (EDDA) and nitrilotriacetate (NTA) to iminodiacetate (IDA) with the production of glyoxylate . The emoA and emoB genes were cotranscribed when BNC1 cells were grown on EDTA . Other genes in the cluster encoded a hypothetical transport system, a putative regulatory protein, and IDA oxidase that oxidizes IDA and EDDA . We concluded that this gene cluster is responsible for the initial steps of EDTA and NTA degradation.

J Biol Chem, 2000 Apr 14, 275(15), 11222 - 8
Characterization of a novel lipid A containing D-galacturonic acid that replaces phosphate residues . The structure of the lipid a of the lipopolysaccharide from the hyperthermophilic bacterium Aquifex pyrophilus; Plotz BM et al.; According to the 16 S rRNA phylogenetic tree, the hyperthermophilic bacterium Aquifex pyrophilus represents the deepest and shortest branching species of the kingdom Bacteria . We show for the first time that an organism, which is phylogenetically ancient on the basis of its 16 S rRNA and that exists at extreme conditions, may contain lipopolysaccharide (LPS) . The LPS was extracted from dried bacteria using a modified phenol/water method . SDS-polyacrylamide gel electrophoresis and silver stain displayed a ladder-like pattern, which is typical for smooth-form LPS (possessing an O-specific polysaccharide) . The molecular masses of the LPS populations were determined by matrix-assisted laser-desorption ionization mass spectrometry . Lipid A was precipitated after mild acid hydrolysis of LPS . Its complete structure was determined by chemical analyses, combined gas-liquid chromatography-mass spectrometry, matrix-assisted laser-desorption ionization mass spectrometry, and one- and two-dimensional NMR spectroscopy . The lipid A consists of a beta-(1-->6)-linked 2,3-diamino-2,3-dideoxy-D-glucopyranose (DAG) disaccharide carrying two residues each of (R)-3-hydroxytetradecanoic acid and (R)-3-hydroxyhexadecanoic acid in amide linkage and one residue of octadecanoic acid in ester linkage . Each DAG moiety carries one residue of each 3-hydroxytetradecanoic and 3-hydroxyhexadecanoic acid . In the nonreducing DAG, the octadecanoic acid is attached to the 3-hydroxy group of 3-hydroxytetradecanoic acid . Each DAG is substituted by one D-galacturonic acid residue, which is linked to O-1 of the reducing and to O-4 of the nonreducing end . This structure represents a novel type of lipid A.

Mutat Res, 2000 Mar 14, 448(1), 47 - 55
The frequency of mutators in populations of Escherichia coli; Boe L et al.; Owing to occasional spontaneous mutations in genes encoding DNA repair, any population of a reasonable size is expected to harbor a sub-population of genetic mutators . Using a genetically modified strain of Escherichia coli K-12, we have estimated the frequency of mutators to be about 3x10(-5) . By and large, this corresponds to a mutation rate from non-mutators to mutators of 5x10(-6) per bacterium per generation . Using a mutS&Colon;Tn10 derivative as representative for mutators, we estimated the increase in mutation rates in mutators to be 19- to 82-fold, depending on the test-mutation under consideration . The load associated with this increase in mutation rate resulted in a growth inhibition of 1% . From these data, we estimated that the rate of detrimental mutations in the non-mutators to be 2x10(-4)-8x10(-4) . The situations where adaptive mutations may result in an increase in the frequency of mutators are discussed.

J Biol Chem, 2001 Apr 6, 276(14), 10971 - 6 Epub 2001 Jan 05.
Biosynthetic controls on the 13C contents of organic components in the photoautotrophic bacterium Chloroflexus aurantiacus; van Der Meer MT et al.; To assess the effects related to known and proposed biosynthetic pathways on the (13)C content of lipids and storage products of the photoautotrophic bacterium Chloroflexus aurantiacus, the isotopic compositions of bulk cell material, alkyl and isoprenoid lipids, and storage products such as glycogen and polyhydroxyalkanoic acids have been investigated . The bulk cell material was 13 per thousand depleted in (13)C relative to the dissolved inorganic carbon . Evidently, inorganic carbon fixation by the main carboxylating enzymes used by C . aurantiacus, which are assumed to use bicarbonate rather than CO(2), results in a relatively small carbon isotopic fractionation compared with CO(2) fixation by the Calvin cycle . Even carbon numbered fatty acids, odd carbon numbered fatty acids, and isoprenoid lipids were 14, 15, and 17-18 per thousand depleted in (13)C relative to the carbon source, respectively . Based on the (13)C contents of alkyl and isoprenoid lipids, a 40 per thousand difference in (13)C content between the carboxyl and methyl carbon from acetyl-coenzyme A has been calculated . Both sugars and polyhydroxyalkanoic acid were enriched in (13)C relative to the alkyl and isoprenoid lipids . To the best of our knowledge this is the first report in which the stable carbon isotopic composition of a large range of biosynthetic products in a photoautotrophic organism has been investigated and interpreted based on previously proposed inorganic carbon fixation and biosynthetic pathways . Our results indicate that compound-specific stable carbon isotope analysis may provide a rapid screening tool for carbon fixation pathways.

J Biol Chem, 2001 Apr 6, 276(14), 11376 - 81 Epub 2001 Jan 03.
A 33-kDa allergen from rice (Oryza sativa L . Japonica) . cDNA cloning, expression, and identification as a novel glyoxalase I; Usui Y et al.; Cereal proteins are known to cause allergic reactions such as Baker's asthma and severe atopic dermatitis to certain populations . In rice allergy, proteins with molecular masses of 14-16, 26, 33, and 56 kDa have been demonstrated to be potentially allergenic . In this study, to identify and characterize the 33-kDa allergen, designated Glb33, this protein was first purified to homogeneity, and its cDNA clone was isolated . When expressed in Escherichia coli, the recombinant Glb33 was shown to be as reactive as the native Glb33 with mouse IgG and patients' IgE antibodies to Glb33 . The Glb33 cDNA coded for a protein of 291 amino acids with two 120-amino acid residue repeats, and the amino acid sequence showed similarity to glyoxalase I from various organisms, including human, plant, yeast, and bacterium . As expected, both native Glb33 purified from rice seeds and the recombinant protein had glyoxalase I activity that catalyzes condensation of methylglyoxal and glutathione into S-lactoylglutathione . However, Glb33 had a higher sequence identity to the bacterial glyoxalase I rather than to known plant and yeast enzymes . Both the Glb33 transcript and the protein were detected not only in maturing seeds of rice but also in its stem and leaf . Taken all together, the rice allergen, Glb33, was identified to be a novel type of plant glyoxalase I that is expressed in various plant tissues, including maturing seeds.

Int J Syst Evol Microbiol, 2000 Nov, 50 Pt 6, 2157 - 63
Thioalkalicoccus limnaeus gen . nov., sp . nov., a new alkaliphilic purple sulfur bacterium with bacteriochlorophyll b; Bryantseva IA et al.; Four strains of purple sulfur bacteria containing bacteriochlorophyll b were isolated from cyanobacterial mats of soda lakes in the steppe of south-east Siberia, Russia . Cells of all strains were cocci without gas vesicles . Eventually, cells with flagella were seen in the electron microscope, but motile cells were observed very rarely in cultures . Internal photosynthetic membranes were of the tubular type . Photosynthetic pigments were bacteriochlorophyll b and carotenoids with spectral characteristics similar to 3,4,3',4'-tetrahydrospirilloxanthin . The bacteria were obligately phototrophic and strictly anaerobic . Hydrogen sulfide and elemental sulfur were used as photosynthetic electron donors . Thiosulfate was not used . During growth on sulfide, sulfur globules were formed as intermediate oxidation products, deposited inside the cells and centrally located . In the presence of sulfide and sodium bicarbonate, acetate, malate, propionate, pyruvate, succinate, fumarate and yeast extract were photoassimilated . Growth factors were not required . The new bacterium is an obligate alkaliphile growing at pH 8-10 with an optimum at pH 9 . It showed good growth up to 6.0% sodium chloride and up to 8.5% sodium carbonates . Phenotypically, it is similar to Thiococcus pfennigii, but different by virtue of its alkaliphily and salt tolerance . The DNA G+C content was 63.6-64.8 mol %, compared to 69.4-69.9 mol % for Thiococcus pfennigii . The 16S rDNA sequence of strain A26T was approximately 92% similar to that of Thiococcus pfennigii DSM 226 and therefore a new genus and species name, Thioalkalicoccus limnaeus gen . nov . and sp . nov., are proposed for the new bacterium.

Int J Syst Evol Microbiol, 2000 Nov, 50 Pt 6, 1989 - 99
Methanomicrococcus blatticola gen . nov., sp . nov., a methanol- and methylamine-reducing methanogen from the hindgut of the cockroach Periplaneta americana; Sprenger WW et al.; A small irregular coccoid methanogenic bacterium (PAT) was isolated from the hindgut of the cockroach Periplaneta americana . Fluorescence microscopy and transmission electron microscopy of the hindgut of P . americana suggest that the organism occurs abundantly in the microbiota attached to the hindgut wall . The strain produces methane by the reduction of methanol and methylated amines with molecular hydrogen . Acetate, coenzyme M, yeast extract, tryptic soy broth and vitamins are required for growth . The cells lack a rigid cell wall and lyse immediately in buffers of low ionic strength . Maximum rate of growth (specific growth rate, 0.22 h(-1)) occurs in a rich medium at 39 degrees C, at a pH range of 7.2-7.7 and at a salt concentration below 100 mM NaCl . Sequence analysis of the small-subunit rDNA indicates that strain PAT is related to the family Methanosarcinaceae but does not belong to any previously described genus . Therefore, it is proposed that strain PAT be classified in a new genus, related to the Methanosarcinaceae, as Methanomicrococcus blatticola (type strain PAT = DSM 13328T).

Int J Syst Evol Microbiol, 2000 Nov, 50 Pt 6, 1965 - 72
Comparative phylogenetic analyses of members of the order Planctomycetales and the division Verrucomicrobia: 23S rRNA gene sequence analysis supports the 16S rRNA gene sequence-derived phylogeny; Ward NL et al.; Almost complete 23S rRNA gene sequences were obtained from 13 planctomycete strains, the fimbriated, prosthecate bacterium Verrucomicrobium spinosum and two strains of the genus Prosthecobacter . The 23S rRNA genes were amplified by the PCR, using modified primers . The majority of the planctomycete strains investigated were shown to have 23S rRNA genes that were not linked to the 16S rRNA genes . Amplification of the 5'-termini of these genes was achieved using a novel primer-design strategy . Comparative phylogenetic analyses were performed using the 23S rRNA gene sequences determined in this study and previously determined 16S rRNA gene sequences . The phylogenetic dendrograms constructed from both datasets showed that the planctomycetes form a coherent group and distinct lineage within the domain Bacteria . Analysis of 23S rRNA gene sequences of Verrucomicrobium spinosum, Prosthecobacter fusiformis and Prosthecobacter sp . strain FC-2 showed that these organisms cluster together, as was also shown here and previously by analysis of 16S rRNA gene sequences . The distinct phylogenetic position of the division Verrucomicrobia was also supported by analysis of the 23S rRNA gene sequences, and no statistically significant phylogenetic relationship between the division Verrucomicrobia and the planctomycetes was found . The analyses presented in this study also provide further evidence that the chlamydiae are no more related to members of the order Planctomycetales and the division Verrucomicrobia than they are to members of other bacterial lineages.

Oral Microbiol Immunol, 2000 Apr, 15(2), 119 - 23
Identification and characterization of human immunoglobulin G Fc receptors of Fusobacterium nucleatum; Guo M et al.; Several human pathogens express components which can bind to the Fc portion of immunoglobulins . This study was undertaken to characterize the human immunoglobulin G (IgG) Fc-binding activity of Fusobacterium nucleatum, a suspected pathogen involved in periodontal diseases . Fc-binding activity was detected using whole-cell, cell envelope and outer membrane fractions, and it was found to be associated with polypeptides of 40 kDa and 42 kDa, respectively . Amino terminal sequencing of these components revealed them to be homologous to the bacterial porin encoded by fomA gene . Further sequencing of internal peptide fragments obtained by CNBr cleavage suggested that these two proteins are probably isoforms . In summary, we show that a porin-like protein on the surface of F . nucleatum can bind the Fc fragment of the human immunoglobulin G, and this protein may act as a virulence factor to facilitate this bacterium in evading host immune surveillance system.

Oral Microbiol Immunol, 2000 Dec, 15(6), 388 - 92
A Porphyromonas gingivalis genetic locus encoding a heme transport system; Slakeski N et al.; Porphyromonas gingivalis has been implicated in the onset and progression of periodontitis and the availability of hemin for in vitro growth has been associated with virulence of the bacterium in animal models . We report here the cloning and sequence analysis of a P . gingivalis TonB-linked outer membrane receptor gene tlr . This gene was previously identified as a TonB-linked adhesin gene tla and shown to be essential for growth at low concentrations of hemin . The tlr gene is immediately downstream of four open reading frames (htrABCD) that encode a putative ATP binding cassette transport system with sequence similarlity to heme transport systems of other bacteria . Analysis of P . gingivalis W50 mRNA revealed that the htrABCD genes are cotranscribed similar to hemin transport genes of other bacteria.

Gesundheitswesen, 2000 Nov, 62(11), 609 - 14
{Q-fever outbreak in Dortmund in the summer of 1999 . Results of an epidemiological outbreak study}; Reintjes R et al.; In the summer of 1999, the health department of the City of Dortmund registered an increased incidence rate of reported Q-fever-diseases . Q-fever is a zoonosis caused by the Coxiella burnetii bacterium which typically multiplies within cells . To investigate the cause of this outbreak, an investigation was initiated . Clinical and veterinary examinations, investigations of the environment and an epidemiological case-control-study were combined . Patients as well as healthy persons interviewed for comparative purposes were asked to complete a questionnaire on their habits of life and the answers compared . The results of this study show a clear connection between an exposition with sheep, dung (OR = 14.9; 95% CI: 4.9-47) and manure (OR = 18.7; 95% CI: 3.5-180) of infected sheep and the Q-fever outbreak . The study confirmed the assumption that a local sheep farm was the source of infection for the epidemic outbreak of Q-fever in the same quarter of Dortmund.

Gesundheitswesen, 2000 Nov, 62(11), 598 - 603
{Helicobacter pylori--prevalence in the German population}; Seher C et al.; Within the framework of the German National Health interview and Examination Survey determinations of IgG-antibodies against the bacterium Helicobacter pylori in serum samples of study participants were conducted . The prevalence for the total population of Germany was 40% . No differences could be found between sexes . The comparison between study participants from the old and those from the new (territory of the former GDR) federal states of Germany did show that the prevalence rates were significantly higher in all age-groups of the eastern part (former GDR) of Germany . Possible causes and factors of influence are discussed.

FEBS Lett, 2000 Dec 29, 487(2), 213 - 8
Fusion of chromatophores from photosynthetic bacteria with a supported lipid layer: characterization of the electric units; Keller S et al.; Direct electrometric measurements of membrane potential changes are a valuable tool for study of vectorial transfer of electrons, protons, and ions . Commonly model membrane systems are created by fusion of lipid/protein vesicles with lipid-coated thin films . We characterized the electric units resulting from this process using chromatophores from the purple bacterium Rhodobacter sphaeroides and either a Mylar film or a planar modified gold electrode as support . Investigation of the shunting activity of the ionophore gramicidin on the flash-induced potential change demonstrates fusion of individual chromatophores to form independent 'blisters', which preserve an interior aqueous compartment . Under current-clamp conditions the photovoltage follows the change of the membrane potential of the individual blisters.

Biochemistry, 2001 Jan 16, 40(2), 464 - 73
Electron transfer may occur in the chlorosome envelope: the CsmI and CsmJ proteins of chlorosomes are 2Fe-2S ferredoxins; Vassilieva EV et al.; Chlorosomes of the green sulfur bacterium Chlorobium tepidum have previously been shown to contain at least 10 polypeptides {Chung, S., Frank, G., Zuber, H., and Bryant, D . A . (1994) Photosynth . Res . 41, 261-275} . Based upon the N-terminal amino acid sequences determined for two of these proteins, the corresponding genes were isolated using degenerate oligonucleotide hybridization probes . The csmI and csmJ genes encode proteins of 244 and 225 amino acids, respectively . A third gene, denoted csmX, that predicts a protein of 221 amino acids with strong sequence similarity to CsmI and CsmJ, was found to be encoded immediately upstream from the csmJ gene . All three proteins have strong sequence similarity in their amino-terminal domains to {2Fe-2S} ferredoxins of the adrenodoxin/putidaredoxin subfamily of ferredoxins . CsmI and CsmJ were overproduced in Escherichia coli, and both proteins were shown by EPR spectroscopy to contain iron-sulfur clusters . The g-tensor and relaxation properties are consistent with their assignment as {2Fe-2S} clusters . Isolated chlorosomes were also shown to contain {2Fe-2S} clusters whose properties were similar to those of the recombinant CsmI and CsmJ proteins . Redox titration of isolated chlorosomes showed these clusters to have potentials of about -201 and +92 mV vs SHE . The former potential is similar to that measured by redox titration of the clusters in inclusion bodies of CsmJ . Possible roles for these iron-sulfur proteins in electron transport and light harvesting are discussed.

Dis Aquat Organ, 2000 Nov 14, 43(2), 117 - 26
A Piscirickettsia salmonis-like bacterium associated with mortality of white seabass Atractoscion nobilis; Chen MF et al.; Mortality among hatchery-reared juvenile white seabass Atractoscion nobilis in southern California, USA, was associated with infections by a Piscirickettsia salmonis-like organism (WSPSLO) . Infected fish had no consistent external signs other than pale gills, lethargy and impaired swimming behavior . Internally, the kidney and spleen were enlarged, and some fish had livers with multiple pale foci . Smears from infected kidney, liver, and spleen stained with Wright-Giemsa had intracytoplasmic coccoid organisms, often in pairs, that ranged in size from 0.5 to 1.0 microm . Microscopic lesions included multifocal hepatic, renal, and splenic necrosis, and intralesional macrophages often contained the WSPSLO . The bacterium was isolated from infected fish on cell lines of salmonid (CHSE-214) and white seabass (WSBK) origin . The WSPSLO induced plaque formation and destroyed the cell monolayers within 10 to 14 d incubation at temperatures of 15 and 20 degrees C . The bacterium retained infectivity for cell lines up to 14 d at 4 and 13 degrees C, up to 7 d at 20 degrees C, but it was inactivated at 37 and 56 degrees C within 24 and 1 h, respectively . Freezing at -20 degrees C reduced infectivity by 100-fold . Dehydration and resuspension in distilled water completely inactivated the bacterium . In contrast, the WSPSLO retained nearly all of its infectivity for CHSE-214 cells following a 72 h period in seawater at 20 degrees C . Polyclonal rabbit antibodies made to the WSPSLO reacted specifically in indirect fluorescent antibody tests (IFAT) with the bacterium in cell cultures and smears from infected fish tissues . Tissue smears from infected salmon or CHSE-214 cells with P . salmonis reacted weakly with the anti-WSPSLO serum . Conversely, polyclonal anti-P . salmonis serum produced a weakly positive reaction with the WSPSLO from infected CHSE-214 cells . The WSPSLO as propagated in CHSE-214 cells was highly virulent for juvenile coho salmon Oncorhynchus kisutch, inducing 80% mortality within 10 d of intraperitoneal injection of 10(2.5)-50% tissue culture infectious doses per fish . We conclude that the bacterium from white seabass possesses antigenic differences from P . salmonis yet possesses virulence for salmon equal to known strains of P . salmonis.

Can J Microbiol, 2000 Dec, 46(12), 1166 - 70
Primary alcohols and di-alcohols as growth substrates for the purple nonsulfur bacterium Rhodobacter capsulatus; Pantazopoulous PE et al.; Growth experiments were performed with the purple nonsulfur bacterium Rhodobacter capsulatus to test its ability to use aliphatic, methyl-substituted, and unsaturated alcohols, as well as di-alcohols, as carbon sources for growth . Both phototrophic and chemotrophic growth was observed on a wide variety of such alcohols . By contrast, secondary or tertiary alcohols, or primary alcohols containing an ethyl or propyl substituent, did not support growth . In addition, preculture history and serial subculturing were found to be important factors for obtaining reliable growth of R . capsulatus on alcohols . Collectively, these results suggest that the carbon nutritional diversity of Rhodobacter capsulatus is even greater than previously suspected and that besides metabolizing organic acids and fatty acids in nature, this species may also be a major consumer of alcohols.

Curr Biol, 2000 Dec 14-28, 10(24), 1615 - 8
A novel bacterial pathogen, Microbacterium nematophilum, induces morphological change in the nematode C . elegans; Hodgkin J et al.; The Dar (deformed anal region) phenotype, characterized by a distinctive swollen tail, was first detected in a variant strain of Caenorhabditis elegans which appeared spontaneously in 1986 during routine genetic crosses {1,2} . Dar isolates were initially analysed as morphological mutants, but we report here that two independent isolates carry an unusual bacterial infection different from those previously described {3}, which is the cause of the Dar phenotype . The infectious agent is a new species of coryneform bacterium, named Microbacterium nematophilum n . sp., which fortuitously contaminated cultures of C . elegans . The bacteria adhere to the rectal and post-anal cuticle of susceptible nematodes, and induce substantial local swelling of the underlying hypodermal tissue . The swelling leads to constipation and slowed growth in the infected worms, but the infection is otherwise non-lethal . Certain mutants of C . elegans with altered surface antigenicity are resistant to infection . The induced deformation appears to be part of a survival strategy for the bacteria, as C . elegans are potentially their predators.

Transfusion, 2000 Dec, 40(12), 1503 - 7
Psoralen photochemical inactivation of Orientia tsutsugamushi in platelet concentrates; Belanger KJ et al.; BACKGROUND: The risk of transfusion transmission of disease has been reduced by the combination of predonation questions and improved transfusion-transmitted disease assays, but the risk is still present . This study was conducted to determine if psoralen photochemistry could inactivate an obligate intracellular bacterium, with documented potential for transfusion, in PCs to further improve safety . STUDY DESIGN AND METHODS: PCs were inoculated with MNCs infected with Orientia tsutsugamushi . The concentrates were treated with amounts ranging from 0.86 to 138 micromol per L of 4'-(aminomethyl)-4,5',8-trimethylpsoralen hydrochloride (AMT) combined with a constant long-wave UVA light (320-400 nm) exposure of 5 J per cm(2) . The effects of photochemical treatment were analyzed by using a mouse infectivity assay along with in vitro testing by PCR, indirect fluorescence antibody, direct fluorescence antibody, and Giemsa staining . RESULTS: AMT, at 0.86 micromol per L or more, combined with UVA light of 5 J per cm(2), inactivated O . tsutsugamushi that contaminated PCs . The PCs that did not receive the combined treatment caused infection . CONCLUSIONS: The psoralen AMT, in conjunction with UVA light exposure, effectively abolished the infectivity of PCs deliberately contaminated with the scrub typhus organism O . tsutsugamushi, as tested in a mouse infectivity assay.

Plant Cell Physiol, 2000 Dec, 41(12), 1347 - 53
Isolation and purification of the reaction center (RC) and the core (RC-LH1) complex from Rhodobium marinum: the LH1 ring of the detergent-solubilized core complex contains 32 bacteriochlorophylls; Qian P et al.; The reaction center (RC) and the core (RC-LH1) complex were isolated and purified from Rhodobium marinum; together with the LH1 complex {Meckenstock et al . (1992a) FEBS Lett . 311: 128}, a complete set of RC, LH1 and RC-LH1 from the same wild-type strain of a purple photosynthetic bacterium can therefore now be made . Comparison of the BChl a/BPhe a ratio (determined by HPLC) between the RC and the RC-LH1 complexes lead us to the determination of the number of BChls in the LH1 ring to be 32.06+/-2.90, indicating that the LH1 ring from Rh . marinum consists of 16 alphabeta subunits.

Parasitology, 2000 Nov, 121 Pt 5, 493 - 500
Physiological cost induced by the maternally-transmitted endosymbiont Wolbachia in the Drosophila parasitoid Leptopilina heterotoma; Fleury F et al.; Endosymbiotic bacteria of the genus Wolbachia infect a number of invertebrate species in which they induce various alterations in host reproduction, mainly cytoplasmic incompatibility (CI) . In contrast to most other maternally transmitted parasites, manipulation of host reproduction makes the spread of Wolbachia possible even if they induce a physiological cost on their hosts . Current studies have shown that fitness consequences of Wolbachia infection could range from positive (mutualist) to negative (parasitic) but, in most cases, Wolbachia do not have strong deleterious effects on host fitness and the status of association remains unclear . Here, we show that in the Drosophila parasitoid wasp Leptopilina heterotoma, Wolbachia infection has a negative impact on several host fitness traits of both sexes . Fecundity, adult survival and locomotor performance are significantly reduced, whereas circadian rhythm, development time and offspring sex-ratio are not affected . Although the cost of bacterial infection can be overcome by effects on host reproduction i.e . cytoplasmic incompatibility, it could influence the spread of the bacterium at the early stages of the invasion process . Clearly, results underline the wide spectrum of phenotypic effects of Wolbachia infection and, to our knowledge, Wolbachia infection of L . heterotoma appears to be one of the most virulent that has ever been observed in insects.

Infect Immun, 2001 Jan, 69(1), 518 - 28
Dendritic cells phagocytose and are activated by Treponema pallidum; Bouis DA et al.; Cell-mediated immune processes play a prominent role in the clinical manifestations of syphilis, a sexually transmitted disease of humans caused by spirochetal bacterium Treponema pallidum . The immune cell type that initiates the early immune response to T . pallidum thus far has not been identified . However, dendritic cells (DCs) are the first immune-competent cells to encounter antigens within skin or mucous membranes, the principal sites of early syphilitic infection . In the present study, immature DC line XS52, derived from murine skin, was utilized to examine T . pallidum-DC interactions and subsequent DC activation (maturation) . Electron microscopy revealed that T . pallidum was engulfed by DCs via both coiling and conventional phagocytosis and was delivered to membrane-bound vacuoles . The XS52 DC line expressed surface CD14 and mRNA for Toll-like receptors 2 and 4, molecules comprising important signaling components for immune cell activation by bacterial modulins . Both T . pallidum and a synthetic lipopeptide (corresponding to the 47-kDa major membrane lipoprotein) activated the XS52 DC line, as indicated by the secretion of interleukin-12 (IL-12), IL-1beta, tumor necrosis factor alpha, and IL-6 and elevated surface expression of CD54 . The combined data support the contention that DCs stimulated by T . pallidum and/or its proinflammatory membrane lipoproteins are involved in driving the cellular immune processes that typify syphilis.

Infect Immun, 2001 Jan, 69(1), 413 - 9
Role of Fc gamma receptors in triggering host cell activation and cytokine release by Borrelia burgdorferi; Talkington J et al.; Borrelia burgdorferi, the spirochetal bacterium that causes human Lyme disease, encodes numerous lipoproteins which have the capacity to trigger the release of proinflammatory cytokines from a variety of host cell types, and it is generally believed that these cytokines contribute to the disease process in vivo . We previously reported that low-passage-number infectious B . burgdorferi spirochetes express a novel lipidation-independent activity which induces secretion of the proinflammatory cytokine tumor necrosis factor alpha (TNF-alpha) by the mouse MC/9 mast cell line . Using RNase protection assays, we determined that mast cells exposed in vitro to low-passage-number, but not high-passage-number, B . burgdorferi spirochetes show increased expression of additional mRNAs representing several chemokines, including macrophage-inflammatory protein 1alpha (MIP-1alpha), MIP-1beta, and TCA3, as well as the proinflammatory cytokine interleukin-6 . Furthermore, mast cell TNF-alpha secretion can be inhibited by the phosphatidylinositol 3-kinase inhibitor wortmannin and also by preincubation with purified mouse immunoglobulin G1 (IgG1) and IgG2a, but not mouse IgG3, and by a mouse Fc gamma receptor II and III (FcgammaRII/III)-specific rat monoclonal antibody, suggesting the likely involvement of host FcgammaRIII in B . burgdorferi-mediated signaling . A role for passively adsorbed rabbit or bovine IgG or serum components in B . burgdorferi-mediated FcgammaR signaling was excluded in control experiments . These studies confirm that low-passage-number B . burgdorferi spirochetes express a novel activity which upregulates the expression of a variety of host cell chemokine and cytokine genes, and they also establish a novel antibody-independent role for FcgammaRs in transduction of activation signals by bacterial products.

Infect Immun, 2001 Jan, 69(1), 177 - 85
Legionella pneumophila major acid phosphatase and its role in intracellular infection; Aragon V et al.; Legionella pneumophila is an intracellular pathogen of protozoa and alveolar macrophages . This bacterium contains a gene (pilD) that is involved in both type IV pilus biogenesis and type II protein secretion . We previously demonstrated that the PilD prepilin peptidase is crucial for intracellular infection by L . pneumophila and that the secreted pilD-dependent proteins include a metalloprotease, an acid phosphatase, an esterase/lipase, a phospholipase A, and a p-nitrophenyl phosphorylcholine hydrolase . Since mutants lacking type IV pili, the protease, or the phosphorylcholine hydrolase are not defective for intracellular infection, we sought to determine the significance of the secreted acid phosphatase activity . Three mutants defective in acid phosphatase activity were isolated from a population of mini-Tn10-mutagenized L . pneumophila . Supernatants as well as cell lysates from these mutants contained minimal acid phosphatase activity while possessing normal levels of other pilD-dependent exoproteins . Genetic studies indicated that the gene affected by the transposon insertions encoded a novel bacterial histidine acid phosphatase, which we designated Map for major acid phosphatase . Subsequent inhibitor studies indicated that Map, like its eukaryotic homologs, is a tartrate-sensitive acid phosphatase . The map mutants grew within macrophage-like U937 cells and Hartmannella amoebae to the same degree as did wild-type legionellae, indicating that this acid phosphatase is not essential for L . pneumophila intracellular infection . However, in the course of characterizing our new mutants, we gained evidence for a second pilD-dependent acid phosphatase activity that, unlike Map, is tartrate resistant.

EMBO J, 2000 Dec 15, 19(24), 6697 - 703
Expression of the endogenous type II secretion pathway in Escherichia coli leads to chitinase secretion; Francetic O et al.; Escherichia coli K-12, the most widely used laboratory bacterium, does not secrete proteins into the extracellular medium under standard growth conditions, despite possessing chromosomal genes encoding a putative type II secretion machinery (secreton) . We show that in wild-type E.coli K-12, divergent transcription of the two operons in the main chromosomal gsp locus, encoding the majority of the secreton components, is silenced by the nucleoid-structuring protein H-NS . In mutants lacking H-NS, the secreton genes cloned on a moderate-copy-number plasmid are expressed and promote efficient secretion of the endogenous, co-regulated endochitinase ChiA . This is the first time that secretion of an endogenous extracellular protein has been demonstrated in E.coli K-12.

Biochim Biophys Acta, 2001 Jan 19, 1503(3), 377 - 84
Purification of ferredoxins and their reaction with purified reaction center complex from the green sulfur bacterium Chlorobium tepidum; Seo D et al.; Four ferredoxin (Fd) fractions, namely, FdA-D were purified from the green sulfur bacterium Chlorobium tepidum . Their absorption spectra are typical of 2{4Fe-4S} cluster type Fds with peaks at about 385 and 280 nm and a shoulder at about 305 nm . The A(385)/A(280) ratios of the purified Fds were 0.76-0.80 . Analysis of the N-terminal amino acid sequences of these Fds (15-25 residues) revealed that those of FdA and FdB completely agree with those deduced from the genes, fdx3 and fdx2, respectively, found in this bacterium (Chung and Bryant, personal communication) . The N-terminal amino acid sequences of FdC and FdD (15 residues) were identical, and agree with that deduced from the gene fdx1 (Chung and Bryant, personal communication) . The A(385) values of these Fds were unchanged when they were stored for a month at -80 degrees C under aerobic conditions and decreased by 10-15% when they were stored for 6 days at 4 degrees C under aerobic conditions, indicating that they are not extremely unstable . In the presence of Fd-NADP(+) reductase from spinach, and a purified reaction center (RC) preparation from C . tepidum composed of five kinds of polypeptides, these Fds supported the photoreduction of NADP(+) at room temperature with the following K(m) and V(max) (in micromol NADP(+) micromol BChl a(-1) h(-1)): FdA, 2.0 microm and 258; FdB, 0.49 microM and 304; FdC, 1.13 microM and 226; FdD, 0.5 microM and 242; spinach Fd, 0.54 microM and 183 . The V(max) value of FdB was more than twice that previously reported for purified RC preparations from green sulfur bacteria.

J Bacteriol, 2001 Jan, 183(1), 171 - 7
Component of the Rhodospirillum centenum photosensory apparatus with structural and functional similarity to methyl-accepting chemotaxis protein chemoreceptors; Jiang ZY et al.; Photosynthetic bacteria respond to alterations in light conditions by migrating to locations that allows optimal use of light as an energy source . Studies have indicated that photosynthesis-driven electron transport functions as an attractant signal for motility among purple photosynthetic bacteria . However, it is unclear just how the motility-based signal transduction system monitors electron flow through photosynthesis-driven electron transport . Recently, we have demonstrated that the purple photosynthetic bacterium Rhodospirillum centenum is capable of rapidly moving swarm cell colonies toward infrared light as well as away from visible light . Light-driven colony motility of R . centenum has allowed us to perform genetic dissection of the signaling pathway that affects photosynthesis-driven motility . In this study, we have undertaken sequence and mutational analyses of one of the components of a signal transduction pathway, Ptr, which appears responsible for transmitting a signal from the photosynthesis-driven electron transport chain to the chemotaxis signal transduction cascade . Mutational analysis demonstrates that cells disrupted for ptr are defective in altering motility in response to light, as well as defective in light-dependent release of methanol . We present a model which proposes that Ptr senses the redox state of a component in the photosynthetic cyclic electron transport chain and that Ptr is responsible for transmitting a signal to the chemotaxis machinery to induce a photosynthesis-dependent motility response.

J Biol Chem, 2001 Mar 16, 276(11), 8393 - 402 Epub 2000 Dec 13.
Substrate and metal complexes of 3-deoxy-D-manno-octulosonate-8-phosphate synthase from Aquifex aeolicus at 1.9-A resolution . Implications for the condensation mechanism; Duewel HS et al.; 3-Deoxy-D-manno-octulosonate-8-phosphate synthase (KDO8PS) from the hyperthermophilic bacterium Aquifex aeolicus differs from its Escherichia coli counterpart in the requirement of a divalent metal for activity (Duewel, H . S., and Woodard, R . W . (2000) J . Biol . Chem . 275, 22824-22831) . Here we report the crystal structure of the A . aeolicus enzyme, which was determined by molecular replacement using E . coli KDO8PS as a model . The structures of the metal-free and Cd(2+) forms of the enzyme were determined in the uncomplexed state and in complex with various combinations of phosphoenolpyruvate (PEP), arabinose 5-phosphate (A5P), and erythrose 4-phosphate (E4P) . Like the E . coli enzyme, A . aeolicus KDO8PS is a homotetramer containing four distinct active sites at the interface between subunits . The active site cavity is open in the substrate-free enzyme or when either A5P alone or PEP alone binds, and becomes isolated from the aqueous phase when both PEP and A5P (or E4P) bind together . In the presence of metal, the enzyme is asymmetric and appears to alternate catalysis between the active sites located on one face of the tetramer and those located on the other face . In the absence of metal, the asymmetry is lost . Details of the active site that may be important for catalysis are visible at the high resolution achieved in these structures . Most notably, the shape of the PEP-binding pocket forces PEP to assume a distorted geometry at C-2, which might anticipate the conversion from sp(2) to sp(3) hybridization occurring during intermediate formation and which may modulate PEP reactivity toward A5P . Two water molecules are located in van der Waals contact with the si and re sides of C-2(PEP), respectively . Abstraction of a proton from either of these water molecules by a protein group is expected to elicit a nucleophilic attack of the resulting hydroxide ion on the nearby C-2(PEP), thus triggering the beginning of the catalytic cycle.

Biochemistry (Mosc), 2000 Nov, 65(11), 1287 - 91
Influence of metal ions on hydrogenase from the purple sulfur bacterium Thiocapsa roseopersicina; Zadvorny OA et al.; The effects of some metal ions on the activity and activation of Thiocapsa roseopersicina hydrogenase have been studied . Inhibitory effects of Ni2+ and Cd2+ on the catalytic activity of the enzyme were reversible and competitive with respect to methyl viologen (MV) in the reaction of hydrogen oxidation . The affinity of these metal ions to the enzyme increased significantly with increasing pH, suggesting that their interactions are determined by electrostatic forces . Cu2+ and Hg2+ irreversibly inhibited the hydrogenase activity . A decrease in absorption of hydrogenase at 400 nm in the presence of these metal ions is indicative of the destruction of the FeS cluster in the enzyme.

FEMS Microbiol Lett, 2000 Dec 15, 193(2), 261 - 8
Isolation and piezoresponse of the rpoA gene encoding the RNA polymerase alpha subunit from the deep-sea piezophilic bacterium Shewanella violacea; Nakasone K et al.; The rpoA gene encoding the alpha subunit of RNA polymerase from the deep-sea piezophilic bacterium Shewanella violacea DSS12 was cloned and sequenced . The rpoA gene was found to encode a polypeptide consisting of 329 amino acids with a molecular mass of 36238 Da . S . violacea alpha protein was expressed in a ts Escherichia coli mutant, to confirm whether the rpoA gene is functional . It complemented this mutation, indicating a chimeric RNA polymerase is assembled at the non-permissive temperature . Recombinant alpha protein was overexpressed using an expression plasmid harboring the rpoA gene and purified to near homogeneity . Primer extension analysis revealed that two transcriptional initiation sites are recognized by sigma(70) RNA polymerase . It also indicated that pressure response (piezoresponse) in the alpha operon occurred at the transcriptional level, suggesting some positive regulators may interact with the transcriptional apparatus and regulate the expression of the operon at different pressure conditions.

FEMS Microbiol Lett, 2000 Dec 15, 193(2), 195 - 200
Production of green fluorescent protein by the methylotrophic bacterium methylobacterium extorquens; Figueira MM et al.; The production of green fluorescent protein (GFP) in Methylobacterium extorquens was studied by creating four different constructs using pJB3KmD, pRK310 and pVK101 vectors, as well as pLac and soluble methane monooxygenase (sMMO) promoters . Plasmids were introduced into the cells by electroporation . Expression of GFP by selected clones was evaluated by growing cells in complex or defined media . The use of pRK310 as an expression vector containing the lacZ promoter resulted in a 100-fold increase of GFP production when compared to cells containing the pLac-GFP-pJB3KmD construct . Higher production of GFP was observed also in cells containing pLac-GFP-pRK310 and pmmoX-GFP-pVK101 constructs . While the transcriptional regulation of the smmo gene in Methylosinus trichosporium OB3b is known to be copper-dependent, expression of GFP by M . extorquens clones harboring pmmoX-promoters was not strongly controlled by the presence of copper in the medium . The production of GFP was generally constant throughout the growth of M . extorquens carrying the pLac-GFP-pRK310 construct . GFP yields varied between 850 and 1000 microg of GFP g biomass(-1) . However, the yield of GFP in cells carrying pmmoX-GFP-pVK101 was somewhat reduced after the mid-exponential phase of growth.

Int Microbiol, 2000 Jun, 3(2), 107 - 11
Isolation and taxonomic study of a new canthaxanthin-containing bacterium, Gordonia jacobaea MV-1 sp . nov; de Miguel T et al.; This article describes the isolation and taxonomic study of a coryneform isolate of a new Gordonia species (G . jacobaea), strain MV-1, which accumulates several carotenoids, including the ketocarotenoid trans-canthaxanthin . Identification of this new isolate by morphobiochemical methods did not allow unambiguous taxon assignment, but sequencing of the 16S rRNA gene clearly pointed to the genus Gordonia, Gordonia sputi being the closest fit . Differences in certain transversions/transitions in otherwise very well-conserved sequences of the described Gordonia species supported the proposal of this new taxon . The fact that both the best growth and best pigmentation were obtained with glucose, an inexpensive carbon source and at an industrially suitable temperature, suggests that this new bacterial strain may have good potential for the industrial production of canthaxanthin.

Biochim Biophys Acta, 2000 Nov 20, 1460(2-3), 338 - 45
Energy transfer and charge separation in the purple non-sulfur bacterium Roseospirillum parvum; Permentier HP et al.; The antenna reaction centre system of the recently described purple non-sulfur bacterium Roseospirillum parvum strain 930I was studied with various spectroscopic techniques . The bacterium contains bacteriochlorophyll (BChl) a, 20% of which was esterified with tetrahydrogeranylgeraniol . In the near-infrared, the antenna showed absorption bands at 805 and 909 nm (929 nm at 6 K) . Fluorescence bands were located at 925 and 954 nm, at 300 and 6 K, respectively . Fluorescence excitation spectra and time resolved picosecond absorbance difference spectroscopy showed a nearly 100% efficient energy transfer from BChl 805 to BChl 909, with a time constant of only 2.6 ps . This and other evidence indicate that both types of BChl belong to a single LH1 complex . Flash induced difference spectra show that the primary electron donor absorbs at 886 nm, i.e . at 285 cm(-1) higher energy than the long wavelength antenna band . Nevertheless, the time constant for trapping in the reaction centre was the same as for almost all other purple bacteria: 55+/-5 ps . The shape as well as the amplitude of the absorbance difference spectrum of the excited antenna indicated exciton interaction and delocalisation of the excited state over the BChl 909 ring, whereas BChl 805 appeared to have a monomeric nature.

Lipids, 2000 Oct, 35(10), 1061 - 4
Production of eicosapentaenoic acid by a recombinant marine cyanobacterium, Synechococcus sp; Yu R et al.; The eicosapentaenoic acid (EPA) synthesis gene cluster from an EPA-producing bacterium, Shewanella sp . SCRC-2738, was cloned into a broad-host range vector, pJRD215, and then introduced into a marine cyanobacterium, Synechococcus sp . NKBG15041c, by conjugation . The transconjugant cyanobacteria produced 3.7 +/- 0.2% (2.24 +/- 0.13 mg/L) EPA (n-3) and 2.5 +/- 0.2% (1.49 +/- 0.06 mg/L) eicosatetraenoic acid (n-3) of the total fatty acids when the cells were cultured at 23 degrees C at a light intensity of 1,000-1,500 Lux . The EPA and eico-satetraenoic acid contents of the cells were increased to 4.6 +/- 0.6% (3.86 +/- 1.11 mg/L) and 4.7 +/- 0.3% (3.86 +/- 0.82 mg/L), and 7.5 +/- 0.3% (1.76 +/- 0.10 mg/L) and 5.1 +/- 0.2% (1.19 +/- 0.06 mg/L) when they were cultured at low temperature (18 degrees C) and at lower light intensity (40 Lux), respectively.

Microbiology, 2000 Dec, 146 Pt 12, 3141 - 7
A new broad-spectrum protease inhibitor from the entomopathogenic bacterium Photorhabdus luminescens; Wee KE et al.; A new protease inhibitor was purified to apparent homogeneity from a culture medium of Photorhabdus luminescens by ammonium sulfate precipitation and preparative isoelectric focusing followed by affinity chromatography . Ph . luminescens, a bacterium symbiotically associated with the insect-parasitic nematode Heterorhabditis bacteriophora, exists in two morphologically distinguishable phases (primary and secondary) . It appears that only the secondary-phase bacterium produces this protease inhibitor . The protease inhibitor has an M:(r) of approximately 12000 as determined by SDS-PAGE . Its activity is stable over a pH range of 3.5-11 and at temperatures below 50 degrees C . The N-terminal 16 amino acids of the protease inhibitor were determined as STGIVTFKND(X)GEDIV and have a very high sequence homology with the N-terminal region of an endogenous inhibitor (IA-1) from the fruiting bodies of an edible mushroom, Pleurotus ostreatus . The purified protease inhibitor inactivated the homologous protease with an almost 1:1 stoichiometry . It also inhibited proteases from a related insect-nematode-symbiotic bacterium, Xenorhabdus nematophila . Interestingly, when present at a molar ratio of 5 to 1, this new protease inhibitor completely inactivated the activity of both trypsin and elastase . The activity of proteinase A and cathepsin G was partially inhibited by this bacterial protease inhibitor, but it had no effect on chymotrypsin, subtilisin, thermolysin and cathepsins B and D . The newly isolated protease inhibitor from the secondary-phase bacteria and its specific inhibition of its own protease provides an explanation as to why previous investigators failed to detect the presence of protease activity in the secondary-phase bacteria . The functional implications of the protease inhibitor are also discussed in relation to the physiology of nematode-symbiotic bacteria.

J Biol Chem, 2001 Mar 16, 276(11), 7734 - 40 Epub 2000 Nov 30.
Reaction mechanism and stereochemistry of gamma-hexachlorocyclohexane dehydrochlorinase LinA; Trantirek L et al.; gamma-Hexachlorocyclohexane dehydrochlorinase (LinA) catalyzes the initial steps in the biotransformation of the important insecticide gamma-hexachlorocyclohexane (gamma-HCH) by the soil bacterium Sphingomonas paucimobilis UT26 . Stereochemical analysis of the reaction products formed during conversion of gamma-HCH by LinA was investigated by GC-MS, NMR, CD, and molecular modeling . The NMR spectra of 1,3,4,5,6-pentachlorocyclohexene (PCCH) produced from gamma-HCH using either enzymatic dehydrochlorination or alkaline dehydrochlorination were compared and found to be identical . Both enantiomers present in the racemate of synthetic gamma-PCCH were converted by LinA, each at a different rate . 1,2,4-trichlorobenzene (1,2,4-TCB) was detected as the only product of the biotransformation of biosynthetic gamma-PCCH . 1,2,4-TCB and 1,2,3-TCB were identified as the dehydrochlorination products of racemic gamma-PCCH . delta-PCCH was detected as the only product of dehydrochlorination of delta-HCH . LinA requires the presence of a 1,2-biaxial HCl pair on a substrate molecule . LinA enantiotopologically differentiates two 1,2-biaxial HCl pairs present on gamma-HCH and gives rise to a single PCCH enantiomer 1,3(R),4(S),5(S),6(R)-PCCH . Furthermore, LinA enantiomerically differentiates 1,3(S),4(R),5(R),6(S)-PCCH and 1,3(R),4(S),5(S),6(R)-PCCH . The proposed mechanism of enzymatic biotransformation of gamma-HCH to 1,2,4-TCB by LinA consists of two 1,2-anti conformationally dependent dehydrochlorinations followed by 1,4-anti dehydrochlorination.

Curr Infect Dis Rep, 1999 Jun, 1(2), 142 - 147
Chlamydia pneumoniae, the Heart, and Coronary Artery Disease: Is There a Cause and Effect Relationship?
O'Donnell JA.
The possibility that infection with Chlamydia pneumoniae may somehow contribute to the pathogenesis of atherosclerosis continues to be explored by researchers worldwide . A direct cause-and-effect relationship between the bacterium and subsequent development of atherosclerosis has yet to be proved . However, compelling indirect evidence continues to mount in favor of this association . In this article the most recent information on this topic is reviewed . Seroepidemiologic and histopathologic evidence will be highlighted, as well as recent animal models of infection and atherosclerosis . In addition, current studies looking at the association of antichlamydial antibiotic use and risk of adverse cardiovascular outcomes will be detailed.

J Bacteriol, 2000 Dec, 182(24), 6921 - 6
Metabolism of acyl-homoserine lactone quorum-sensing signals by Variovorax paradoxus; Leadbetter JR et al.; Acyl-homoserine lactones (acyl-HSLs) serve as dedicated cell-to-cell signaling molecules in many species of the class Proteobacteria . We have addressed the question of whether these compounds can be degraded biologically . A motile, rod-shaped bacterium was isolated from soil based upon its ability to utilize N-(3-oxohexanoyl)-L-homoserine lactone as the sole source of energy and nitrogen . The bacterium was classified as a strain of Variovorax paradoxus . The V . paradoxus isolate was capable of growth on all of the acyl-HSLs tested . The molar growth yields correlated with the length of the acyl group . HSL, a product of acyl-HSL metabolism, was used as a nitrogen source, but not as an energy source . Cleavage and partial mineralization of the HSL ring were demonstrated by using radiolabeled substrate . This study indicates that some strains of V . paradoxus degrade and grow on acyl-HSL signals as the sole energy and nitrogen sources . This study provides clues about the metabolic pathway of acyl-HSL degradation by V . paradoxus.

DNA Seq, 2000, 11(3-4), 207 - 10
Sequencing the Sinorhizobium meliloti genome; Galibert F et al.; The Sinorhizobium meliloti genome consists of three replicons . This bacterium forms an intricate symbiotic relationship with the roots of certain legumes and is considered as an agriculturally important nitrogen-fixer . A consortium of 6 European laboratories was organized to sequence its single chromosome (3.7 Mb), whereas the other two elements (pSyma 1.4 Mb and pSymb 1.7 Mb) will be sequenced by other groups.

Appl Microbiol Biotechnol, 2000 Oct, 54(4), 564 - 9
The carbon source influences the energetic efficiency of the respiratory chain of N2-fixing Acetobacter diazotrophicus; Luna MF et al.; Acetobacter diazotrophicus is a diazotrophic bacterium that colonizes sugarcane tissues . Glucose is oxidized to gluconate in the periplasm prior to uptake and metabolism . A membrane-bound glucose dehydrogenase quinoenzyme {which contains pyrroloquinoline quinone (PQQ) as the prosthetic group} is involved in that oxidation . Gluconate is oxidized further via the hexose monophosphate pathway and tricarboxylic acid cycle . A . diazotrophicus PAL3 was grown in a chemostat with atmospheric nitrogen as the sole N source provided that the dissolved oxygen was maintained at 1.0-2.0% air saturation . The biomass yields of A . diazotrophicus growing with glucose or gluconate with fixed N were very low compared with other heterotrophic bacteria . The biomass yields under N-fixing conditions were more than 30% less than with ammonium as the N source using gluconate as the carbon source but, surprisingly, were only about 14% less with glucose . The following scheme for the metabolism of A . diazotrophicus through the different pathways emerged: (1) the respiratory chain of this organism had a different efficiency of ATP production in the respiratory chain (P:O ratio) under different culture conditions; and (2) N fixation was one (but not the sole) condition under which a higher P:O ratio was observed . The other condition appears to be the expression of an active PQQ-linked glucose dehydrogenase.

J Chromatogr B Biomed Sci Appl, 2000 Oct 1, 748(1), 167 - 77
Use of non-porous reversed-phase high-performance liquid chromatography for protein profiling and isolation of proteins induced by temperature variations for Siberian permafrost bacteria with identification by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry and capillary electrophoresis-electrospray ionization mass spectrometry; Chong BE et al.; Non-porous reversed-phase high-performance liquid chromatography (NP-RP-HPLC) has been used to separate and isolate proteins from whole cell lysates of ED 7-3, a bacterium from the buried Siberian permafrost sediment . The proteins collected from the liquid eluent of this separation were then analyzed by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) and capillary electrophoresis-electrospray ionization mass spectrometry (CE-ESI-MS) . In order to study the differences in expression of cold-shock proteins (CSPs) at different growth temperatures, cultures of the ED 7-3 strain were prepared at 4 degrees C and 25 degrees C . The goals of this work were twofold: firstly, to identify the presence of CSPs and other proteins that are highly expressed at 4 degrees C but not at 25 degrees C; and secondly, to isolate these proteins for MALDI-TOF-MS and CE-ESI-MS identification . In this initial work, distinct protein profiles were observed for these cultures as a function of temperature . Fraction collection from the eluent of NP-RP-HPLC of some of the highly expressed proteins was performed and the proteins were mass analyzed for molecular mass . Peptide maps of the proteins were generated by tryptic digestion and were analyzed by CE-ESI-MS and MALDI-TOF-MS for database identification of the expressed proteins.

Bioorg Med Chem, 2000 Nov, 8(11), 2609 - 16
Binding of vancomycin group antibiotics to D-alanine and D-lactate presenting self-assembled monolayers; Cooper MA et al.; Peptides terminating in -Lys-D-Ala-D-Ala, -Lys-D-Ala-L-Ala and -Lys-D-Ala-D-Lactate were covalently coupled via an N-terminal aminohexanoic acid linker to a self-assembled monolayer of HS(CH2)15CO2H on a thin gold film . Binding of the glycopeptide antibiotics vancomycin and chloroeremomycin to these surfaces was then measured using a surface plasmon resonance biosensor . Both antibiotics bound with micromolar affinity to the D-Ala-terminating surface and with millimolar affinity to the D-Lactate-terminating surface . Increasing density of these covalently attached peptides on the surface had no effect on the resultant affinities of either antibiotic for the surface . In contrast, when the lipid-anchored peptide N-alpha-docosanoyl-epsilon-acetyl-Lys-D-Ala-D-Ala was inserted into a supported lipid monolayer, the affinity of the strongly dimerizing antibiotic chloroeremomycin for the surface showed a dependence on ligand density . This was not the case with the weakly dimerizing antibiotic vancomycin . The lipid monolayer surface, which is a more realistic model of the surface of a bacterium, was thus better suited for the study of the cooperative binding interactions that occur between dimeric glycopeptide antibiotics and surface-bound ligands.

Microbiol Immunol, 2000, 44(9), 773 - 6
Adherence protects the binding sites of Helicobacter pylori urease from acid-induced damage; Icatlo FC et al.; Colonization by Helicobacter pylori partly depends on acid-dependent adherence by urease to gastric mucin . To further verify the relevance of urease adherence to colonization, the influence of acidity on the binding sites of H . pylori urease was investigated . When enzyme-based in vitro ligand capture assays were used, the effect of acidity on the binding site of H . pylori urease was determined against a backdrop medium consisting of acidic buffers simulating the luminal side of gastric mucus . A high degree of stability was exhibited by adherent urease, suggesting a pivotal role by the denatured enzyme in the persistence of the bacterium within the acidified compartment of gastric mucus.

Phys Rev E Stat Phys Plasmas Fluids Relat Interdiscip Topics, 2000 Jul, 62(1 Pt B), 1034 - 44
Bacterial turgor pressure can be measured by atomic force microscopy; Arnoldi M et al.; We report a study of the deformability of a bacterial wall with an atomic force microscope (AFM) . A theoretical expression is derived for the force exerted by the wall on the cantilever as a function of the depths of indentation generated by the AFM tip . Evidence is provided that this reaction force is a measure for the turgor pressure of the bacterium . The method was applied to magnetotactic bacteria of the species Magnetospirillum gryphiswaldense . Force curves were generated on the substrate and on the bacteria while scanning laterally . With the mechanical properties so gained we obtained the spring constant of the bacterium as a whole . Making use of our theoretical results we determined the turgor pressure to be in the range of 85 to 150 kPa.

J Agric Food Chem, 2000 Nov, 48(11), 5146 - 53
Determination of spinosad and its metabolites in food and environmental matrices . 3 . Immunoassay methods; Young DL et al.; Spinosad is an insect control agent that is derived from a naturally occurring soil bacterium and is effective on several classes of insects, especially Lepidopteran larvae . Spinosad is registered in many countries for use on a variety of crops, including cotton, corn, soybeans, fruits, and vegetables . Residue methods utilizing a magnetic particle-based immunoassay (IA) test kit have been developed and validated for determining spinosad in environmental and food matrices . These methods involve an extraction of the residues from the matrices with appropriate solvents . For some matrices, the sample extracts can be diluted and measured directly by IA without any cleanup . For other matrices, sample extracts are purified using liquid-liquid partitioning and/or solid phase extraction prior to measurement by IA . The methods determine the total residue of spinosad, which includes the active ingredients (spinosyns A and D) and several minor metabolites, including spinosyn B, spinosyn K, and N-demethylspinosyn D . The methods have validated limits of quantitation of 0.0001 microgram/mL in water, 0.05 microgram/g in sediment, and 0.010 microgram/g in crops, crop processed commodities, and animal tissues . This paper briefly summarizes the residue methodology and method validation data for spinosad in 34 food, feed, and environmental matrices.

J Agric Food Chem, 2000 Nov, 48(11), 5131 - 7
Determination of spinosad and its metabolites in food and environmental matrices . 1 . High-performance liquid chromatography with ultraviolet detection; West SD et al.; Spinosad is an insect control agent that is derived from a naturally occurring soil bacterium and is effective on several classes of insects, especially Lepidoptera larvae . Spinosad is registered in many countries for use on a variety of crops, including cotton, corn, soybeans, fruits, and vegetables . Residue methods utilizing high-performance liquid chromatography (HPLC) with ultraviolet (UV) detection have been described for determining spinosad and its metabolites in environmental and food matrices . These residue methods typically involve an extraction with organic solvents, followed by purification using liquid-liquid partitioning and/or solid phase extraction prior to measurement by HPLC-UV . The residue methods determine the active ingredients (spinosyns A and D) and up to three minor metabolites (spinosyn B, spinosyn K, and N-demethylspinosyn D) . The methods have validated limits of quantitation ranging from 0.010 to 0.040 microgram/g . This paper briefly reviews the residue methodology for spinosad and metabolites in food and environmental matrices and provides a summary of method validation results for 61 different sample types, including newly published results for 37 additional crop matrices and processed commodities.

Biochemistry, 2000 Nov 21, 39(46), 14232 - 7
Aspartate-187 of cytochrome b is not needed for DCCD inhibition of ubiquinol: cytochrome c oxidoreductase in Rhodobacter sphaeroides chromatophores; Shinkarev VP et al.; N,N'-dicyclohexylcarbodiimide (DCCD) has been reported to inhibit steady-state proton translocation by cytochrome bc(1) and b(6)f complexes without significantly altering the rate of electron transport, a process referred to as decoupling . In chromatophores of the purple bacterium Rhodobacter sphaeroides, this has been associated with the specific labeling of a surface-exposed aspartate-187 of the cytochrome b subunit of the bc(1) complex {Wang et al . (1998) Arch . Biochem . Biophys . 352, 193-198} . To explore the possible role of this amino acid residue in the protonogenic reactions of cytochrome bc(1) complex, we investigated the effect of DCCD modification on flash-induced electron transport and the electrochromic bandshift of carotenoids in Rb . sphaeroides chromatophores from wild type (WT) and mutant cells, in which aspartate-187 of cytochrome b (Asp(B187)) has been changed to asparagine (mutant B187 DN) . The kinetics and amplitude of phase III of the electrochromic shift of carotenoids, reflecting electrogenic reactions in the bc(1) complex, and of the redox changes of cytochromes and reaction center, were similar (+/- 15%) in both WT and B187DN chromatophores . DCCD effectively inhibited phase III of the carotenoid bandshift in both B187DN and WT chromatophores . The dependence of the kinetics and amplitude of phase III of the electrochromic shift on DCCD concentration was identical in WT and B187DN chromatophores, indicating that covalent modification of Asp(B187) is not specifically responsible for the effect of DCCD-induced effects of cytochrome bc(1) complex . Furthermore, no evidence for differential inhibition of electrogenesis and electron transport was found in either strain . We conclude that Asp(B187) plays no crucial role in the protonogenic reactions of bc(1) complex, since its replacement by asparagine does not lead to any significant effects on either the electrogenic reactions of bc(1) complex, as revealed by phase III of the electrochromic shift of carotenoids, or sensitivity of turnover to DCCD.

Infect Immun, 2000 Dec, 68(12), 6770 - 6
Involvement of CD14 and beta2-integrins in activating cells with soluble and particulate lipopolysaccharides and mannuronic acid polymers; Flo TH et al.; Lipopolysaccharide (LPS) and related bacterial products can be recognized by host inflammatory cells in a particulate, bacterium-bound form, as well as in various soluble, released forms . In the present study we have compared the mechanisms used by LPS, detoxified LPS (DLPS), and mannuronic acid polymers (M-polymers), in solution or covalently linked to particles, in stimulating monocytes to tumor necrosis factor (TNF) production . The addition of recombinant LPS binding protein (LBP) and/or soluble CD14 (sCD14) enhanced the production of TNF from monocytes stimulated with soluble LPS, DLPS, or M-polymer, but did not affect the response to M-polymer or DLPS attached to particles . Treatment of monocytes with antibody to CD14, CD18, or CD11b showed that CD14, but not CR3 (CD11b/CD18), mediated monocyte TNF production in response to the soluble antigens . In contrast, anti-CD14, anti-CD11b and anti-CD18 monoclonal antibodies all inhibited the response to the particulate stimuli . On the other hand, B975, a synthetic analog of Rhodobacter capsulatus lipid A, completely abrogated the monocyte TNF response induced by LPS but did not affect the TNF induction by DLPS or M-polymer, either in soluble or particulate forms . These data demonstrate that the engagement of immune receptors by bacterial products such as LPS, DLPS, and M-polymer is dependent upon the presentation form of their constituent carbohydrates, and that factors such as aggregation state, acylation, carbohydrate chain length, and solid versus liquid phase of bacterial ligands influence the mechanisms used by cells in mediating proinflammatory responses.

Infect Immun, 2000 Dec, 68(12), 6750 - 7
Hemin-binding surface protein from Bartonella quintana; Carroll JA et al.; Bartonella quintana, the agent of trench fever and a cause of endocarditis and bacillary angiomatosis in humans, has the highest reported in vitro hemin requirement for any bacterium . We determined that eight membrane-associated proteins from B . quintana bind hemin and that a approximately 25-kDa protein (HbpA) was the dominant hemin-binding protein . Like many outer membrane proteins, HbpA partitions to the detergent phase of a Triton X-114 extract of the cell and is heat modifiable, displaying an apparent molecular mass shift from approximately 25 to 30 kDa when solubilized at 100 degrees C . Immunoblots of purified outer and inner membranes and immunoelectron microscopy with whole cells show that HbpA is strictly located in the outer membrane and surface exposed, respectively . The N-terminal sequence of mature HbpA was determined and used to clone the HbpA-encoding gene (hbpA) from a lambda genomic library . The hbpA gene is 816 bp in length, encoding a predicted immature protein of approximately 29.3 kDa and a mature protein of 27.1 kDa . A Fur box homolog with 53% identity to the Escherichia coli Fur consensus is located upstream of hbpA and may be involved in regulating expression . BLAST searches indicate that the closest homologs to HbpA include the Bartonella henselae phage-associated membrane protein, Pap31 (58.4% identity), and the OMP31 porin from Brucella melitensis (31.7% identity) . High-stringency Southern blots indicate that all five pathogenic Bartonella spp . possess hbpA homologs . Recombinant HbpA can bind hemin in vitro; however, it does not confer a hemin-binding phenotype upon E . coli . Intact B . quintana treated with purified anti-HbpA Fab fragments show a significant (P < 0.004) dose-dependent decrease in hemin binding relative to controls, suggesting that HbpA plays an active role in hemin acquisition and therefore pathogenesis . HbpA is the first potential virulence determinant characterized from B . quintana.

Infect Immun, 2000 Dec, 68(12), 6677 - 84
Identification of 11 pH-regulated genes in Borrelia burgdorferi localizing to linear plasmids; Carroll JA et al.; When Borrelia burgdorferi is transmitted from the tick vector to the mammalian host, the bacterium experiences alterations in its environment, such as changes in temperature and pH . Previously, we observed numerous alterations in the membrane protein profile when B . burgdorferi B31 was grown at pH 7.0 compared to pH 8.0 . Here we identify 11 genes localizing to linear plasmids that are up-regulated at pH 7.0 relative to pH 8.0 in vitro . Seven genes (bba03, bba24, bba64, bba66, bbe31, bbj41/bbi39 {encoding products that are 99% identical}, and bbk01) were indirectly identified by proteomic analysis of membrane proteins . Another gene, bba36, was identified by screening a B . burgdorferi B31 genomic library with cross-adsorbed hyperimmune rabbit serum . Two additional genes, bba65 and bba73, were identified by Northern blot analysis . Genes bba64, bba65, bba66, bbj41/bbi39, and bba73 are members of paralogous gene family 54, and bbe31 is a member of the closely related paralogous gene family 60 . Gene bba24 is part of a bicistronic operon with bba25 that encodes the well-characterized decorin binding proteins A and B . All 11 genes were transcriptionally regulated, yet the degree of pH regulation varied, with some genes more tightly regulated than others . The regions upstream of these pH-regulated genes appeared to be unrelated, yet many contained dyad repeats ranging from 12 to 25 nucleotides in length that may be involved in the regulation of these genes.

Infect Immun, 2000 Dec, 68(12), 6580 - 6
impA, a gene coding for an inner membrane protein, influences colonial morphology of Actinobacillus actinomycetemcomitans; Mintz KP et al.; Directed mutagenesis of a gene coding for a membrane protein of the periodontopathogen Actinobacillus actinomycetemcomitans was achieved by conjugation . The gene was disrupted by insertion of an antibiotic cassette into a unique endonuclease restriction sequence engineered by inverse PCR . The disrupted gene was cloned into a conjugative plasmid and transferred from Escherichia coli to A . actinomycetemcomitans . The allelic replacement mutation resulted in the loss of a 22-kDa inner membrane protein . The loss of this protein (ImpA) resulted in changes in the outer membrane protein composition of the bacterium . Concurrent with the mutation in impA was a change in the pattern of growth of the mutant bacteria in broth cultures . The progenitor bacteria grew as a homogeneous suspension of cells compared to a granular, autoaggregating adherent cell population described for the mutant bacteria . These data suggest that ImpA may play a regulatory role or be directly involved in protein(s) that are exported and associated with colony variations in A . actinomycetemcomitans.

J Mol Evol, 2000 Nov, 51(5), 433 - 45
Molecular evolution of the myeloperoxidase family; Daiyasu H et al.; Animal myeloperoxidase and its relatives constitute a diverse protein family, which includes myeloperoxidase, eosinophil peroxidase, thyroid peroxidase, salivary peroxidase, lactoperoxidase, ovoperoxidase, peroxidasin, peroxinectin, cyclooxygenase, and others . The members of this protein family share a catalytic domain of about 500 amino acid residues in length, although some members have distinctive mosaic structures . To investigate the evolution of the protein family, we performed a comparative analysis of its members, using the amino acid sequences and the coordinate data available today . The results obtained in this study are as follows: (1) 60 amino acid sequences belonging to this family were collected by database searching . We found a new member of the myeloperoxidase family derived from a bacterium . This is the first report of a bacterial member of this family . (2) An unrooted phylogenetic tree of the family was constructed according to the alignment . Considering the branching pattern in the obtained phylogenetic tree, together with the mosaic features in the primary structures, 60 members of the myeloperoxidase family were classified into 16 subfamilies . (3) We found two molecular features that distinguish cyclooxygenase from the other members of the protein family . (4) Several structurally deviated segments were identified by a structural comparison between cyclooxygenase and myeloperoxidase . Some of the segments seemed to be associated with the functional and/or structural differences between the enzymes.

J Antibiot (Tokyo), 2000 Aug, 53(8), 759 - 64
Characterization of B-5354c, a new sphingosine kinase inhibitor, produced by a marine bacterium; Kono K et al.; B-5354c is a new inhibitor of sphingosine kinase from a novel marine bacterium, SANK 71896 . Kinetic study revealed that B-5354c inhibits sphingosine kinase with a Ki value of 12/microM . The inhibition is noncompetitive with respect to sphingosine . The compound also inhibits sphingosine-1-phosphate formation in human platelets . Experiments using synthetic derivatives of B-5354c indicate that all the three functional groups, i.e., the long unsaturated aliphatic chain, 4-amino and 3-hydroxyl groups are necessary to inhibit sphingosine kinase.

J Food Prot, 2000 Nov, 63(11), 1517 - 22
Detection of guaiacol produced by Alicyclobacillus acidoterrestris in apple juice by sensory and chromatographic analyses, and comparison with spore and vegetative cell populations; Orr RV et al.; Spoilage of fruit juice by Alicyclobacillus acidoterrestris is characterized by a distinct medicinal or antiseptic off odor attributed to guaiacol, a metabolic by product of the bacterium . Detection of low populations of A . acidoterrestris that would precede sensory detection of guaiacol would enable juice processors to select appropriate processing and storage conditions that would minimize or eliminate spoilage . The objective of this study was to determine the recognition threshold of guaiacol in apple juice by sensory analysis and the population of A . acidoterrestris and incubation time at 21 and 37 degrees C necessary for chemical detection of guaiacol . Commercially sterilized apple juice (pH 3.54 +/- 0.04, 11.3 +/- 0.3 degrees Brix) was inoculated with a five-strain mixture of A . acidoterrestris spores (2.98 log10 CFU/ml) and stored at 21 or 37 degrees C for up to 61 days . Using an experienced sensory panel and the forced-choice ascending concentration method of limits, the best estimate threshold (BET) for recognition of guaiacol added to uninoculated apple juice was 2.23 ppb . Numbers of A . acidoterrestris spores and cells in inoculated juice remained constant during the 61-day storage period; however, the panel detected (P < or = 0.01) guaiacol in juice stored at 37 degrees C within 8 days . At three of four sampling times ranging from 13 to 61 days at which the sensory panel detected (P < or = 0.001) guaiacol, concentrations of 8.1 to 11.4 ppb were detected by chromatographic analysis . The panel detected (P < or = 0.1 to P < or = 0.01) guaiacol in five samples stored at 21 to 37 degrees C for 8 to 61 days in which the compound was not detected by chromatographic analyses . It appears that guaiacol content in apple juice inoculated with A . acidoterrestris is not always correlated with numbers of cells, and the limit of sensitivity of chromatographic quantitation of the compound is higher than the BET.

Cell Immunol, 2000 Oct 10, 205(1), 13 - 23
Utilization of CD11b knockout mice to characterize the role of complement receptor 3 (CR3, CD11b/CD18) in the growth of Mycobacterium tuberculosis in macrophages; Melo MD et al.; Using CD11b knockout mice as a source of macrophages (Mphi;), we show that complement receptor 3 (CR3) mediates approximately 40-50% of nonopsonic binding and 50-60% of serum-mediated binding of Mycobacterium tuberculosis to resident Mphi; . We demonstrate that opsonic binding of M . tuberculosis to Mphi; is mediated by an immunoglobulin-independent, heat-labile component of serum, in both the presence and the absence of CD11b . The survival and replication of M . tuberculosis in an in vitro Mphi; model and an in vivo mouse model of infection were not significantly affected by the absence of CD11b, indicating that CR3-mediated uptake of M . tuberculosis is not a major factor in controlling the subsequent intracellular survival of the mycobacteria . However, whether a mycobacterium will gain access to the intracellular environment, and the type of Mφ that the bacterium enters, is significantly affected by the presence or absence of CR3 .

Proc Natl Acad Sci U S A, 2000 Nov 21, 97(24), 13407 - 12
Genetic analysis of calcium spiking responses in nodulation mutants of Medicago truncatula; Wais RJ et al.; The symbiotic interaction between Medicago truncatula and Sinorhizobium meliloti results in the formation of nitrogen-fixing nodules on the roots of the host plant . The early stages of nodule formation are induced by bacteria via lipochitooligosaccharide signals known as Nod factors (NFs) . These NFs are structurally specific for bacterium-host pairs and are sufficient to cause a range of early responses involved in the host developmental program . Early events in the signal transduction of NFs are not well defined . We have previously reported that Medicago sativa root hairs exposed to NF display sharp oscillations of cytoplasmic calcium ion concentration (calcium spiking) . To assess the possible role of calcium spiking in the nodulation response, we analyzed M . truncatula mutants in five complementation groups . Each of the plant mutants is completely Nod- and is blocked at early stages of the symbiosis . We defined two genes, DMI1 and DMI2, required in common for early steps of infection and nodulation and for calcium spiking . Another mutant, altered in the DMI3 gene, has a similar mutant phenotype to dmi1 and dmi2 mutants but displays normal calcium spiking . The calcium behavior thus implies that the DMI3 gene acts either downstream of calcium spiking or downstream of a common branch point for the calcium response and the later nodulation responses . Two additional mutants, altered in the NSP and HCL genes, which show root hair branching in response to NF, are normal for calcium spiking . This system provides an opportunity to use genetics to study ligand-stimulated calcium spiking as a signal transduction event.

Biol Chem, 2000 Sep-Oct, 381(9-10), 993 - 9
Helical tubes of FtsZ from Methanococcus jannaschii; Lowe J et al.; Bacterial cell division depends on the formation of a cytokinetic ring structure, the Z-ring . The bacterial tubulin homologue FtsZ is required for Z-ring formation . FtsZ assembles into various polymeric forms in vitro, indicating a structural role in the septum of bacteria . We have used recombinant FtsZ1 protein from M . jannaschii to produce helical tubes and sheets with high yield using the GTP analogue GMPCPP {guanylyl-(alpha,beta)-methylene-diphosphate} . The sheets appear identical to the previously reported Ca++-induced sheets of FtsZ from M . jannaschii that were shown to consist of 'thick'-filaments in which two protofilaments run in parallel . Tubes assembled either in Ca++ or in GMPCPP contain filaments whose dimensions indicate that they could be equivalent to the 'thick'-filaments in sheets . Some tubes are hollow but others are filled by additional protein density . Helical FtsZ tubes differ from eukaryotic microtubules in that the filaments curve around the filament axis with a pitch of approximately 430 A for Ca++-induced tubes or 590 - 620 A for GMPCPP . However, their assembly in vitro as well-ordered polymers over distances comparable to the inner circumference of a bacterium may indicate a role in vivo . Their size and stability make them suitable for use in motility assays.

Cephalalgia, 2000 Jul, 20(6), 561 - 5
Association between Helicobacter pylori cytotoxic type I CagA-positive strains and migraine with aura; Gasbarrini A et al.; Recent studies have suggested an association between Helicobacter pylori infection and migraine . However, various strains of the bacterium are present, some endowed with greater pathogenicity . In particular, H . pylori type I CagA-positive strains induce a higher release of proinflammatory substances by the gastric mucosa that could trigger systemic vasospasms . The aim of the present study was to assess the prevalence of H . pylori CagA-positive strains in subjects with migraine . One hundred and seventy-five patients affected by migraine (49 with aura, 126 without aura) were consecutively enrolled and matched for sex, age, social background and geographical origin with 152 controls . Helicobacter pylori infection was assessed through 13C-urea breath test . Specific serological IgG against CagA were detected through ELISA . The prevalence of H . pylori infection was similar in migraine patients and in controls (40% vs . 39%, respectively) . Among migraine patients, prevalence of infection was not related to presence or absence of aura (45% vs . 37%, respectively) . However, among infected subjects, a significantly higher prevalence of CagA-positive strains was observed in patients affected by migraine with aura when compared with those affected by migraine without aura (41% vs . 19%, P < 0.01) and with controls (41% vs . 17%, P < 0.01) . CagA-positive H . pylori strains were found to be strongly associated with migraine with aura . A higher inflammatory response of the gastric mucosa to more virulent strains could release substances that may act as triggers of vasospasm in peculiar cerebral arterial districts, probably implicated in the 'aura' phenomenon.

J Bacteriol, 2000 Dec, 182(23), 6732 - 41
Gene cloning and molecular characterization of lysine decarboxylase from Selenomonas ruminantium delineate its evolutionary relationship to ornithine decarboxylases from eukaryotes; Takatsuka Y et al.; Lysine decarboxylase (LDC; EC 4.1.1.18) from Selenomonas ruminantium comprises two identical monomeric subunits of 43 kDa and has decarboxylating activities toward both L-lysine and L-ornithine with similar K(m) and V(max) values (Y . Takatsuka, M . Onoda, T . Sugiyama, K . Muramoto, T . Tomita, and Y . Kamio, Biosci . Biotechnol . Biochem . 62:1063-1069, 1999) . Here, the LDC-encoding gene (ldc) of this bacterium was cloned and characterized . DNA sequencing analysis revealed that the amino acid sequence of S . ruminantium LDC is 35% identical to those of eukaryotic ornithine decarboxylases (ODCs; EC 4.1.1.17), including the mouse, Saccharomyces cerevisiae, Neurospora crassa, Trypanosoma brucei, and Caenorhabditis elegans enzymes . In addition, 26 amino acid residues, K69, D88, E94, D134, R154, K169, H197, D233, G235, G236, G237, F238, E274, G276, R277, Y278, K294, Y323, Y331, D332, C360, D361, D364, G387, Y389, and F397 (mouse ODC numbering), all of which are implicated in the formation of the pyridoxal phosphate-binding domain and the substrate-binding domain and in dimer stabilization with the eukaryotic ODCs, were also conserved in S . ruminantium LDC . Computer analysis of the putative secondary structure of S . ruminantium LDC showed that it is approximately 70% identical to that of mouse ODC . We identified five amino acid residues, A44, G45, V46, P54, and S322, within the LDC catalytic domain that confer decarboxylase activities toward both L-lysine and L-ornithine with a substrate specificity ratio of 0.83 (defined as the k(cat)/K(m) ratio obtained with L-ornithine relative to that obtained with L-lysine) . We have succeeded in converting S . ruminantium LDC to form with a substrate specificity ratio of 58 (70 times that of wild-type LDC) by constructing a mutant protein, A44V/G45T/V46P/P54D/S322A . In this study, we also showed that G350 is a crucial residue for stabilization of the dimer in S . ruminantium LDC.

Can J Microbiol, 2000 Oct, 46(10), 908 - 12
Bartonella henselae infection in British Columbia: evidence for an endemic disease among humans; Cimolai N et al.; Human bartonellosis in North America is mainly associated with Bartonella henselae, and the availability of laboratory diagnostic tools has significantly heightened awareness of the spectrum of human disease that is caused by this bacterium . We detail herein examples of illness in a pediatric population which serve to confirm that B . henselae-associated disease exists in British Columbia . Seroprevalence studies among asymptomatic adults and among children with symptomatic respiratory illness of other causation demonstrated that 36.8% and 18.5% of sera, respectively, had IFA-IgG titres > or = 1:256 . IFA-IgG titres did not vary significantly whether B . henselae ATCC 49793 or a local wild-type B . henselae isolate were used as substrate . An assessment of IgM response was consistent with the proposal that endemic seroprevalence is a function of past rather than recent exposure . Both clinical and serological studies are concordant in providing evidence that B . henselae is endemic in British Columbia.

Minerva Stomatol, 2000 May, 49(5), 227 - 48
{Neutrophil physiology: role and mechanism of action in the immune response at gingival level}; Del Fabbro M et al.; Polymorphonuclear neutrophil granulocytes (PMN) are considered the most important cells of the host immune response against bacterial challenge . The functional mechanism of PMN consists of different steps: tethering, rolling, primary adhesion to the vascular wall, firm adhesion to the activated endothelium in the inflamed region, trans-migration across endothelium, chemotaxis, contact with the bacterium and phagocytosis and, finally, killing of the micro-organism by releasing hydrolytic enzymes and/or by production of toxic substances such as free radicals . Each of these steps is controlled by interactions between cells and many components of the immune system or inflammatory mediators . These interactions generate specific signals, important for cell regulation . Recent technological advances in molecular biology and immunobiology allowed to disclose the precise role of various molecules involved in the immune response, that regulate PMN function; conversely, more factors have been identified, whose role is still unknown . In the process of adhesion, for example, many classes of molecules are involved (selectins, integrins, ICAMs) . The interaction of these molecules (es.: selectin) with their ligands (non completely discovered) is characteristic of specific stages, but may also regulate the successive steps (integrin activation) . In periodontal infections, PMNs of gingival tissue migrate towards bacteria of dental plaque along a chemotactic gradient of specific factors (ICAM-1, IL-8) produced by cells of the junctional epithelium . Such gradient is essential to drive PMNs through molecular traffic . Among the mechanisms used by PMNs to kill bacteria, the importance of nitric oxide (NO) production has been recently pointed out.

Circulation, 2000 Nov 7, 102(19), 2341 - 6
Detection of Chlamydia pneumoniae DNA in CD3+ lymphocytes from healthy blood donors and patients with coronary artery disease; Kaul R et al.; BACKGROUND: Chlamydia pneumoniae is an intracellular bacterium responsible for respiratory tract infections . Recent studies have implicated this organism in the pathogenesis of atherosclerosis . METHODS AND RESULTS: To address how the organism is transported from lungs to cardiac vessels, we characterized the cell population within peripheral blood mononuclear cells (PBMCs) that harbor C pneumoniae DNA . Adherent and nonadherent PBMCs from 28 patients with coronary artery disease (CAD) and 19 healthy blood donors were evaluated for the presence of C pneumoniae DNA by touchdown nested polymerase chain reaction (nPCR) . Of the 28 patients, 10 (36%) had detectable PCR product in their nonadherent and 3 (10%) in their adherent PBMC population . C pneumoniae-specific PCR results were positive for 5 of 19 (26%) healthy blood donors . PCR positivity was detected only in the nonadherent cell population among this group of individuals . Fractionation of nonadherent PBMCs identified C pneumoniae-specific PCR signal among the CD3+ T-cell population exclusively . Of the 18 PCR-positive subjects (13 patients and 5 healthy control subjects), 67% (8 patients and 4 healthy blood donors) tested positive for C pneumoniae-specific IgG serology . Interestingly, 2 patients became PCR negative on a repeated blood draw 5 months after initial detection of C pneumoniae DNA despite retaining C pneumoniae-specific antibodies . CONCLUSIONS: Our results demonstrate marginally significant prevalence of C pneumoniae DNA in patients with CAD compared with healthy subjects (P=0.082) . In contrast, the prevalence of IgG seropositivity among the 2 groups did not reach statistical significance (P=0.306) . We also provide unequivocal evidence for the presence of C pneumoniae DNA predominantly among the circulating CD3+ T-cell population.

Microbiology, 2000 Nov, 146 ( Pt 11), 2957 - 66
A periplasmic, alpha-type carbonic anhydrase from Rhodopseudomonas palustris is essential for bicarbonate uptake; Puskas LG et al.; Intact cells of the purple non-sulfur bacterium Rhodopseudomonas palustris growing anaerobically, but not aerobically, contain carbonic anhydrase (CA) activity . The native enzyme was purified >2000-fold to apparent homogeneity and found to be a dimer with an estimated molecular mass of 54 kDa and a subunit molecular mass of 27 kDa . The CA gene (acaP) was cloned and its sequence revealed that it was homologous to alpha-type CAs . The upstream region of acaP was fused to the lacZ gene and beta-galactosidase activity was measured under different growth conditions . Acetazolamide inhibited purified CA with an IC(50) in the range of 10(-8) M, and in the culture media concentrations as low as 30 microM inhibited phototrophic growth under anaerobic, light conditions when bicarbonate was used . An acaP::KAN:(r) mutant strain was constructed by insertion of a kanamycin-resistance cassette and showed a growth pattern similar to wild-type cells grown in the presence of CA inhibitor . CO(2) gas supplied as an inorganic carbon source reversed the effect of mutation or acetazolamide . CA activity measurements, fusion and Western blot experiments confirmed that CA is expressed under different anaerobic conditions independently of bicarbonate or CO(2) and that there is no expression under aerobic conditions.

Microbiology, 2000 Nov, 146 ( Pt 11), 2815 - 24
Xenorhabdus bovienii T228 phase variation and virulence are independent of RecA function; Pinyon RA et al.; Colony pleomorphism, or phase variation, expressed by entomopathogenic bacteria belonging to the genus Xenorhabdus, is an important factor which determines the association of the bacteria with their nematode symbiont and the outcome of infection of susceptible insect larvae by the bacterium- nematode parasitic complex . The mechanism underlying phase variation is unknown . To determine whether RecA-mediated processes are linked to phase variation, the recA gene of Xenorhabdus bovienii was cloned and sequenced . When expressed in a recA-deleted strain of Escherichia coli, the X . bovienii recA clone was able to complement the loss of RecA function . X . bovienii chromosomal recA insertion mutants showed increased sensitivity to UV . Phase 1 forms did not show altered ability to convert to phase 2 and no significant differences in expression of other phase-dependent characteristics, including phospholipase C, haemolysin, protease, antibiotic activity and Congo Red binding, were noted . Furthermore, the LD(50) of the X . bovienii recA insertion mutant for Galleria mellonella larvae was not significantly different from that of wild-type strains . From these data the authors conclude that recA is unlikely to be involved in phase variation, the expression of phase-dependent characteristics, or virulence factors involved in killing of susceptible larvae.

Enzyme Microb Technol, 2000 Nov 15, 27(9), 691 - 697
At-line monitoring of a submerged filamentous bacterial cultivation using near-infrared spectroscopy; Arnolda SA et al.; The use of near infra-red spectroscopy (NIRS) to monitor a submerged filamentous bacterial bioprocess was investigated . An industrial strain of the filamentous bacterium Streptomyces fradiae was cultured in a 12 litre stirred tank reactor (STR) using a complex medium . This mycelial 4 phase (oil, water, gas and solid) system produced highly complex and variable matrices, therefore monitoring such a complex fluid with NIRS represented a considerable challenge . Nevertheless, successful models for four key analytes (methyl oleate, glucose, glutamate and ammonium) were built at-line (rapid off-line) using NIRS . In the present study, the methods used to formulate, select and validate the models for the key analytes are discussed, with particular emphasis on how the model performance can be critically evaluated . Since previous reports on NIRS in monitoring bioprocesses have either involved simpler matrices, or, in filamentous systems, have not discussed how NIRS models can be critically assessed, the emphasis in the present study on providing an insight into the modelling process in such a complex matrix, may be particularly important to the applicability of NIRS to such industrial bioprocesses.

Rheumatol Int, 2000, 19(6), 219 - 22
Failure to detect Bartonella henselae infection in synovial fluid from sufferers of chronic arthritis; Dillon B et al.; Bartonella henselae causes granulomatous and indolent infection in the immune competent human, and angioproliferation in the context of persistent infection and impaired immunity . This bacterium is found in up to 40% of household cats, from which humans acquire it by either a cat scratch or a bite (hence the name, cat-scratch disease) . Approximately 5% of Australian and US blood donors have serological evidence of past infection, but most associated illnesses are mild or subclinical . A number of lines of evidence prompted us to consider a relationship between rheumatoid arthritis (RA) and Bartonella infection . These include epidemiological associations with household pet exposure; apparent responsiveness of some RA cases to tetracycline therapy; the granulomatous and angioproliferative nature of Bartonella lesions; the insidiousness and high seroprevalence of this infection in the community; and even reported Bartonella infection mimicking juvenile RA . In a small group of patients with chronic arthritides, we found no direct evidence of humoral antibodies to, nor of persistent infection with, Bartonella henselae in synovial fluid . While larger and more invasive studies are likely to provide more confident exclusions of this hypothesis, this suggests that persistent Bartonella infection is unlikely to play a major role in RA.

Dig Liver Dis, 2000 Aug-Sep, 32(6), 468 - 72
Diet and duodenal ulcer; Misciagna G et al.; BACKGROUND: Despite the fact that the main cause of duodenal ulcer incidence and recurrence is the Helicobacter pylori bacterium, more than 80% of Helicobacter pylori-infected people never develop an ulcer . Diet may be one of the most important environmental factors contributing to duodenal ulcer . AIMS: To explore the role of diet in causation, treatment and prevention of duodenal ulcer recurrence . METHODS: All research papers published in English from 1966 to October 1999 present in Medline, involving human subjects, and having duodenal ulcer as outcome, entered the review . RESULTS AND CONCLUSIONS: Soluble fibre from fruit and vegetables seem to be protective against duodenal ulcer and refined sugars a risk factor . The role of fibre in the treatment and prevention of recurrence of duodenal ulcer is uncertain, as is that of essential fatty acids . However, none of the epidemiological studies on the relationship between diet and duodenal ulcer disease controlled for Helicobacter pylori.

Appl Environ Microbiol, 2000 Nov, 66(11), 5019 - 23
Oxygen-dependent growth of the sulfate-reducing bacterium Desulfovibrio oxyclinae in coculture with Marinobacter sp . Strain MB in an aerated sulfate-depleted chemostat; Sigalevich P et al.; A chemostat coculture of the sulfate-reducing bacterium Desulfovibrio oxyclinae and the facultatively aerobic heterotroph Marinobacter sp . strain MB was grown for 1 week under anaerobic conditions at a dilution rate of 0.05 h(-1) . It was then exposed to an oxygen flux of 223 micromol min(-1) by gassing the growth vessel with 5% O(2) . Sulfate reduction persisted under these conditions, though the amount of sulfate reduced decreased by 45% compared to the amount reduced during the initial anaerobic mode . After 1 week of growth under these conditions, sulfate was excluded from the incoming medium . The sulfate concentration in the growth vessel decreased exponentially from 4.1 mM to 2.5 microM . The coculture consumed oxygen effectively, and no residual oxygen was detected during either growth mode in which oxygen was supplied . The proportion of D . oxyclinae cells in the coculture as determined by in situ hybridization decreased from 86% under anaerobic conditions to 70% in the microaerobic sulfate-reducing mode and 34% in the microaerobic sulfate-depleted mode . As determined by the most-probable-number (MPN) method, the numbers of viable D . oxyclinae cells during the two microaerobic growth modes decreased compared to the numbers during the anaerobic growth mode . However, there was no significant difference between the MPN values for the two modes when oxygen was supplied . The patterns of consumption of electron donors and acceptors suggested that when oxygen was supplied in the absence of sulfate and thiosulfate, D . oxyclinae performed incomplete aerobic oxidation of lactate to acetate . This is the first observation of oxygen-dependent growth of a sulfate-reducing bacterium in the absence of either sulfate or thiosulfate . Cells harvested during the microaerobic sulfate-depleted stage and exposed to sulfate and thiosulfate in a respiration chamber were capable of anaerobic sulfate and thiosulfate reduction.

Appl Environ Microbiol, 2000 Nov, 66(11), 5013 - 8
Sulfate reduction and possible aerobic metabolism of the sulfate-reducing bacterium Desulfovibrio oxyclinae in a chemostat coculture with Marinobacter sp . Strain MB under exposure to increasing oxygen concentrations; Sigalevich P et al.; A chemostat coculture of the sulfate-reducing bacterium Desulfovibrio oxyclinae together with a facultative aerobe heterotroph tentatively identified as Marinobacter sp . strain MB was grown under anaerobic conditions and then exposed to a stepwise-increasing oxygen influx (0 to 20% O(2) in the incoming gas phase) . The coculture consumed oxygen efficiently, and no residual oxygen was detected with an oxygen supply of up to 5% . Sulfate reduction persisted at all levels of oxygen input, even at the maximal level, when residual oxygen in the growth vessel was 87 microM . The portion of D . oxyclinae cells in the coculture decreased gradually from 92% under anaerobic conditions to 27% under aeration . Both absolute cell numbers and viable cell counts of the organism were the same as or even higher than those observed in the absence of oxygen input . The patterns of consumption of electron donors and acceptors suggest that aerobic incomplete oxidation of lactate to acetate is performed by D . oxyclinae under high oxygen input . Both organisms were isolated from the same oxic zone of a cyanobacterial mat where they have to adapt to daily shifts from oxic to anoxic conditions . This type of syntrophic association may occur in natural habitats, enabling sulfate-reducing bacteria to cope with periodic exposure to oxygen.

Bioorg Med Chem Lett, 2000 Oct 16, 10(20), 2353 - 6
Highly sensitive and rapid detection of antibody catalysis by luminescent bacteria; Shulman H et al.; A highly sensitive, inexpensive, and facile bioluminescent assay for the detection of catalytic antibodies has been developed . This assay may be used for the early detection of antibody catalysis . The efficiency of this technique was exemplified by the use of the luminescent bacterium VhM42 for monitoring an antibody-catalyzed retroaldol fragmentation reaction with aldolase antibodies 38C2 and 24H6.

Tuber Lung Dis, 2000, 80(4-5), 237 - 42
Deletion of the putative antioxidant noxR1 does not alter the virulence of Mycobacterium tuberculosis H37Rv; Stewart GR et al.; SETTING: The cloned M . tuberculosis noxR1 gene has been shown to confer resistance to reactive nitrogen intermediates (RNI) and reactive oxygen intermediates (ROI) upon Escherichia coli and Mycobacterium smegmatis . OBJECTIVE: To investigate the role of noxR1 in resistance to RNI and virulence of M . tuberculosis . DESIGN: The noxR1 gene was deleted from M . bovis BCG and M . tuberculosis H37Rv by allelic exchange . The mutants were compared to wild type strains with respect to resistance to chemically generated RNI . The virulence of the M . tuberculosis mutant was investigated in a murine model of infection . RESULTS: The NoxR1 mutants grew normally in Sautons and 7H9 broths . The BCG mutant demonstrated decreased resistance to in vitro generated RNI compared to the wild type . Resistance to RNI could be restored to the mutant by reintroduction of the noxR1 locus on a replicating plasmid . However, deletion of noxR1 from M . tuberculosis H37Rv did not result in decreased resistance to RNI nor a difference in growth and survival of the bacterium during murine infection . CONCLUSION: The noxR1 gene locus in M . bovis BCG bestows ability to resist RNI generated in vitro . In M . tuberculosis H37Rv, however, noxR1 is either not involved in RNI resistance and virulence or is better compensated for by other mechanisms . 2000 Harcourt Publishers Ltd.

Biol Trace Elem Res, 2000 Summer, 75(1-3), 167 - 75
Microcalorimetric study of Escherichia coli growth inhibited by the selenomorpholine complexes; Li X et al.; The inhibitory or antibiotic action of four kinds of the selenomorpholine complex on a strain of Escherichia coli was studied by microcalorimetry . Differences in their capacities to inhibit the metabolism of this bacterium were observed . The extent and duration of the inhibitory effect on the metabolism as judged from the rate constant, k, and the half-inhibitory concentration, IC50, varied with the different drugs . The rate constant (k) of Escherichia coli (in the log phase) in the presence of the drugs decreased with increasing concentrations of the drugs (C) . The relationship of k and C is nearly linear for (1) selenomorpholine and (2) selenomorpholine hydrochloride, but for (3) N,N'-methylene bisselenomorpholine and (4) N-dodecyl selenomorpholine, it is not linear . The experimental results reveal that the sequence of antibiotic activity of selenomorpholines is (3) and (4) > (1) > (2).

FEMS Microbiol Ecol, 2000 Oct 1, 34(1), 1 - 7
Measuring growth of a phenanthrene-degrading bacterial inoculum in soil with a quantitative competitive polymerase chain reaction method; Schwartz E et al.; We measured growth of a phenanthrene-degrading bacterium, Arthrobacter, strain RP17, in Forbes soil, amended with 500 microg g(-1) phenanthrene using a quantitative competitive polymerase chain reaction method . The inoculum, which was not indigenous to Forbes soil, grew from 5.55x10(5) colony forming units (cfu) g(-1) to 1.97x10(7) cfu g(-1) within 100 h after the cells were added to the soil . Maximum population density was reached before the highest degradation rate was observed 150 h after the cells were added to soil . Population density remained stable even after 56% of the phenanthrene had mineralized . This study is one of the few documented examples of growth by a non-indigenous bacterium in a non-sterile soil amended with a pollutant.

Curr Opin Microbiol, 2000 Oct, 3(5), 459 - 62
A genomic approach to the understanding of Xylella fastidiosa pathogenicity; Lambais MR et al.; Xylella fastidiosa is a fastidious, xylem-limited bacterium that causes several economically important plant diseases, including citrus variegated chlorosis (CVC) . X . fastidiosa is the first plant pathogen to have its genome completely sequenced . In addition, it is probably the least previously studied of any organism for which the complete genome sequence is available . Several pathogenicity-related genes have been identified in the X . fastidiosa genome by similarity with other bacterial genes involved in pathogenesis in plants, as well as in animals . The X . fastidiosa genome encodes different classes of proteins directly or indirectly involved in cell-cell interactions, degradation of plant cell walls, iron homeostasis, anti-oxidant responses, synthesis of toxins, and regulation of pathogenicity . Neither genes encoding members of the type III protein secretion system nor avirulence-like genes have been identified in X . fastidiosa.

Lijec Vjesn, 2000 Jul-Aug, 122(7-8), 187 - 91
{Trachoma--an endemic and post-endemic problem}; Bujger Z et al.; Trachoma is a specific chronic keratoconjunctivitis, characterized by follicular and papillary hyperplasia of conjunctiva, pannus, and cicatrization in the late stages of the disease . The cause of trachoma is a bacterium, Chlamydia trachomatis (serovar A, B, Ba and C) . There are 146 million people in the world suffering from the active trachoma disease, and 5.9 million are blind because of it . WHO has set the goal to eliminate the blinding trachoma by the year 2020 (GET 2020 Program) . The evaluation of the gravity of the disease has been made according to the Trachoma Simplified Grading System . In order to achieve the goal, it has used the SAFE strategy . The SAFE strategy comprises surgery for trichiasis, antibiotics, facial cleanliness and environmental improvement, especially in water supply and regulated sewage . The endemic trachoma in Croatia is a thing of past . Patients with active disease are rare, usually misdiagnosed and inadequately or insufficiently treated . A recent epidemic of another chlamydial (oculogenital sexually transmitted) disease has forced us to approach the diagnostics and treatment of chlamydial diseases with full responsibility.

Protein Sci, 2000 Sep, 9(9), 1730 - 42
Tryptophanyl fluorescence lifetime distribution of hyperthermophilic beta-glycosidase from molecular dynamics simulation: a comparison with the experimental data; Bismuto E et al.; A molecular dynamics simulation approach has been utilized to understand the unusual fluorescence emission decay observed for beta-glycosidase from the hyperthermophilic bacterium Solfolobus sulfotaricus (Sbeta gly), a tetrameric enzyme containing 17 tryptophanyl residues for each subunit . The tryptophanyl emission decay of Sbeta gly results from a bimodal distribution of fluorescence lifetimes with a short-lived component centered at 2.5 ns and a long-lived one at 7.4 ns (Bismuto E, Nucci R, Rossi M, Irace G, 1999, Proteins 27:71-79) . From the examination of the trajectories of the side chains capable of causing intramolecular quenching for each tryptophan microenvironment and using a modified Stern-Volmer model for the emission quenching processes, we calculated the fluorescence lifetime for each tryptophanyl residue of Sbeta gly at two different temperatures, i.e., 300 and 365 K . The highest temperature was chosen because in this condition Sbeta gly evidences a maximum in its catalytic activity and is stable for a very long time . The calculated lifetime distributions overlap those experimentally determined . Moreover, the majority of trytptophanyl residues having longer lifetimes correspond to those originally identified by inspection of the crystallographic structure . The tryptophanyl lifetimes appear to be a complex function of several variables, such as microenvironment viscosity, solvent accessibility, the chemical structure of quencher side chains, and side-chain dynamics . The lifetime calculation by MD simulation can be used to validate a predicted structure by comparing the theoretical data with the experimental fluorescence decay results.

Can J Surg, 2000 Oct, 43(5), 339 - 46
Helicobacter and disease: still more questions than answers; Kandel G; Since the causative role of Helicobacter pylori in peptic ulcer and gastritis was established, a number of advances have been made . Helicobacter virulence factors have been identified, the changes it causes in gastric acid secretion has been elucidated, and the entire genome of H . pylori has been mapped . Multiple lines of evidence indicate a strong link between the bacterium and noncardia gastric cancer . The infection can be confidently diagnosed by noninvasive serologic tests and the urea breath test . Triple therapy is almost always curative, and the infection almost never recurs in Canadian adults, but eradicating the bacteria in the absence of peptic ulcer only rarely leads to resolution of dyspepsia . New studies suggest that treating Helicobacter may increase the risk of peptic esophagitis and adenocarcinoma of the esophagus and cardia.

Biochemistry (Mosc), 2000 Sep, 65(9), 1060 - 7
Structure of an acidic O-specific polysaccharide of the marine bacterium Pseudoalteromonas sp . KMM 634; Komandrova NA et al.; An acidic O-specific polysaccharide containing D-glucuronic acid (D-GlcA), 2,3-diacetamido-2,3-dideoxy-D-glucuronic acid (D-GlcNAc3NAcA), 2,3-diacetamido-2,3-dideoxy-D-mannuronoyl-L-alanine (D-ManNAc3NAcA6Ala), and 2-acetamido-2,4, 6-trideoxy-4-{(S)-3-hydroxybutyramido}-D-glucose (D-QuiNAc4NAcyl) was obtained by mild acid degradation of the lipopolysaccharide of the bacterium Pseudoalteromonas sp . KMM 634 followed by gel-permeation chromatography . The polysaccharide was cleaved selectively with a new solvolytic agent, trifluoromethanesulfonic acid, to give a disaccharide and a trisaccharide with D-GlcNAc3NAcA at the reducing end . The borohydride-reduced oligosaccharides and the initial polysaccharide were studied by GLC-MS and 1H- and 13C-NMR spectroscopy, and the following structure of the linear tetrasaccharide repeating unit of the polysaccharide was established: -->3)-alpha-D-QuipNAc4Ac4NAcyl-(1-->4)-beta-D-ManpNAc3NAcA6Ala+ ++-(1-->4)-b eta-D-GlcpNAc3NAc3NAcA-(1-->4)-beta-D-GlcpA-(1-->.

Biochem J, 2000 Nov 1, 351 Pt 3, 567 - 78
An examination of how structural changes can affect the rate of electron transfer in a mutated bacterial photoreaction centre; Ridge JP et al.; A series of reaction centres bearing mutations at the (Phe) M197 position were constructed in the photosynthetic bacterium Rhodobacter sphaeroides . This residue is adjacent to the pair of bacteriochlorophyll molecules (P(L) and P(M)) that is the primary donor of electrons (P) in photosynthetic light-energy transduction . All of the mutations affected the optical and electrochemical properties of the P bacteriochlorophylls . A mutant reaction centre with the change Phe M197 to Arg (FM197R) was crystallized, and a structural model constructed at 2.3 A (1 A=0.1 nm) resolution . The mutation resulted in a change in the structure of the protein at the interface region between the P bacteriochlorophylls and the monomeric bacteriochlorophyll that is the first electron acceptor (B(L)) . The new Arg residue at the M197 position undergoes a significant reorientation, creating a cavity at the interface region between P and B(L) . The acetyl carbonyl substituent group of the P(M) bacteriochlorophyll undergoes an out-of-plane rotation, which decreases the edge-to-edge distance between the macrocycles of P(M) and B(L) . In addition, two new buried water molecules partially filled the cavity that is created by the reorientation of the Arg residue . These waters are in a suitable position to connect the macrocycles of P and B(L) via three hydrogen bonds . Transient absorption measurements show that, despite an inferred decrease in the driving force for primary electron transfer in the FM197R reaction centre, there is little effect on the overall rate of the primary reaction in the bulk of the reaction-centre population . Examination of the X-ray crystal structure reveals a number of small changes in the structure of the reaction centre in the interface region between the P and B(L) bacteriochlorophylls that could account for this faster-than-predicted rate of primary electron transfer.

FEMS Microbiol Lett, 2000 Nov 1, 192(1), 91 - 5
Glutamine synthetase gene expression at elevated hydrostatic pressure in a deep-sea piezophilic Shewanella violacea; Ikegami A et al.; A glutamine synthetase gene (glnA) was isolated from a deep-sea piezophilic bacterium, Shewanella violacea strain DSS12 . A 7.5-kb SacI fragment containing the complete glnA gene was cloned and sequenced . The glnA gene was found to encode a protein consisting of 469 amino acid residues, showing 75.0% identity to the glutamine synthetase of Escherichia coli . Primer extension analyses revealed two transcription initiation sites in glnA and expression from each site was positively regulated by pressure . Putative promoters recognized by sigma(70) and sigma(54) were identified in the region upstream of glnA . An electrophoretic mobility shift assay demonstrated that S . violacea sigma(54) specifically binds to the promoter region of glnA, suggesting that sigma(54) may play an important role in pressure-regulated transcription in this piezophilic bacterium.

Chang Gung Med J, 2000 Aug, 23(8), 467 - 75
DNA polymorphism of Mycobacterium abscessus analyzed by infrequent-restriction-site polymerase chain reaction; Su LH et al.; BACKGROUND: Mycobacterium abscessus is an important pathogen that has been increasingly associated with many clinical and nosocomial infections . A reliable molecular typing scheme is essential for the epidemiological study of this rapidly growing mycobacterium . Pulsed-field gel electrophoresis (PFGE), considered to be the gold standard among molecular typing methods, has failed to provide satisfactory results in the molecular typing of this bacterium . A newly developed molecular typing method, infrequent-restriction-site polymerase chain reaction (IRS-PCR), was examined in this study to determine its suitability for fingerprinting M . abscessus isolates . METHODS: Eight clinical isolates of M . abscessus and two reference strains (M . abscessus ATCC 19977 and M . chelonae ATCC 35749) were studied by DNA macrorestriction analysis with XbaI resolved by PFGE, and IRS-PCR assay with adaptors designed for XbaI and HhaI restriction sites . RESULTS: By PFGE, different banding patterns were found in two clinical isolates of M . abscessus; the other isolates yielded only broken DNA and could not be assessed . By IRS-PCR, unique patterns were noted for the 10 isolates; the 10 appeared to be genetically different . CONCLUSION: IRS-PCR may be an efficient substitute for PFGE in analyzing the DNA polymorphism and epidemiology of M . abscessus.

FEMS Microbiol Lett, 2000 Sep 15, 190(2), 203 - 8
Molybdate-dependent expression of dimethylsulfoxide reductase in Rhodobacter capsulatus; Solomon PS et al.; Expression of the dimethylsulfoxide respiratory (dor) operon of Rhodobacter is regulated by oxygen, light intensity and availability of substrate . Since dimethylsulfoxide reductase contains a pterin molybdenum cofactor, the role of molybdate in the regulation of dor operon expression was investigated . In this report we show that the molybdate-responsive transcriptional regulator, MopB, and molybdate are essential for maximal dimethylsulfoxide reductase activity and expression of a dorA::lacZ transcriptional fusion in Rhodobacter capsulatus . In contrast, mop genes are not required for the expression of the periplasmic nitrate reductase or xanthine dehydrogenase in R . capsulatus under conditions of molybdenum sufficiency . This is the first report demonstrating a clear functional difference between the ModE homologues MopB and MopA in this bacterium . The results suggest that MopA is primarily involved in the regulation of nitrogen fixation gene expression in response to molybdate while MopB has a role in nitrogen fixation and dimethylsulfoxide respiration.

Z Gastroenterol, 2000 Aug, 38(8), 627 - 30
Comparative analysis of the Helicobacter pylori status in patients with gastric MALT-type lymphoma and their respective spouses; Fischbach W et al.; Helicobacter pylori is of major importance for the development and progression of gastric MALT-type lymphoma . In case of localized low grade lymphoma successfully treated by Helicobacter pylori eradication reinfection by the bacterium may involve the risk of lymphoma reoccurrence . AIMS: To assess the frequency and type of Helicobacter pylori infection among patients with gastric MALT-type lymphoma and their respective spouses as potential sources of person to person spread of the infection . SUBJECTS: 35 patients with gastric MALT-type lymphoma and their cohabiting spouses . METHODS: We investigated serum IgG titers in response to the infection by Helicobacter pylori and to its virulence factors CagA and VacA by enzyme linked immunosorbent assay (ELISA) and by Western blot . RESULTS: Seropositivity of Helicobacter pylori, Cag A and Vac A was found to be 100/89/69% and 97/86/66% in patients and respective partners, respectively . The seroprevalence rates of the latter group by far exceed those of the German population . CONCLUSION: These data provide evidence for a high Helicobacter pylori infection rate in both patients with gastric MALT-type lymphoma and their respective spouses . Considering the latter as a potential source of reinfection with the risk of lymphoma reoccurrence for the successfully treated patient with gastric MALT-type lymphoma careful follow-up seems highly reasonable to decide on the necessity of a future test-and-treat strategy of this population.

Genomics, 2000 Oct 15, 69(2), 235 - 41
Application of bootstrap techniques to physical mapping; Heber S et al.; Ordering genetic markers or clones from a genomic library into a physical map is a central problem in genetics . In the presence of errors, there is no efficient algorithm known that solves this problem . Based on a standard heuristic algorithm for it, we present a method to construct a confidence neighborhood for a computed solution . We compute a confidence value for putative local solutions derived from bootstrap replicates of the original solution . In the reliable parts, the confidence neighborhood and the computed solution tend to coincide . In regions that are ill-defined by the data, the neighborhood contains additional reasonable alternatives . This offers the possibility of designing further experiments for the badly defined regions to improve the quality of the physical map . We analyze our approach by a simulation study and by application to a dataset of the genome of the bacterium Xylella fastidiosa .

Science, 2000 Oct 13, 290(5490), 347 - 50
Selfish DNA in protein-coding genes of Rickettsia; Ogata H et al.; Rickettsia conorii, the aetiological agent of Mediterranean spotted fever, is an intracellular bacterium transmitted by ticks . Preliminary analyses of the nearly complete genome sequence of R . conorii have revealed 44 occurrences of a previously undescribed palindromic repeat (150 base pairs long) throughout the genome . Unexpectedly, this repeat was found inserted in-frame within 19 different R . conorii open reading frames likely to encode functional proteins . We found the same repeat in proteins of other Rickettsia species . The finding of a mobile element inserted in many unrelated genes suggests the potential role of selfish DNA in the creation of new protein sequences.

Gastroenterol Clin North Am, 2000 Sep, 29(3), 705 - 51
Gastric pathology associated with Helicobacter pylori; Warren JR; A bacterium is associated with a specific gastritis . Neutrophils infiltrate the necks of the glands, just deep to the infected foveolae . This infiltration rarely, if ever, occurs without H . pylori infection . Foveolar epithelial damage is common, with loss of cell structure . Electron microscopy suggests that the bacteria cause this damage as they attach to the superficial cell membrane . These features, defined by Whitehead et al as active changes, appear specific for H . pylori infection . The neutrophils and specific epithelial changes disappear within days of starting treatment for Helicobacter . They rapidly recur if the treatment is unsuccessful . Without treatment, the changes remain for decades and are severe in 10% to 20% of cases . Other changes occur in the mucosa . Reduced mucus secretion occurs in damaged or proliferating epithelium . This reduced secretion occurs near healing ulcers or with other types of inflammation but is often severe when Helicobacter is present . It returns to normal within weeks of treating the infection . The bacteria adhering to the cell membrane may cause this change directly . Lymphoid infiltration occurs with any type of chronic inflammation or immune reaction . The infiltration is not specific for Helicobacter, and it reduces slowly in months or years after eradication of H . pylori . Peptic ulceration, particularly duodenal ulceration, although not specific, is particularly common with H . pylori infection . The long-term inflammation probably causes other gastric pathology . Atrophy is common . Epithelial metaplasia occurs in about 20% of patients, usually mild . Other features, such as scarring, epithelial dysplasia, and in situ malignant change, are less common . They show little improvement after eradicating H . pylori . The part played by the bacteria in their cause remains uncertain . Pathologists see a long-standing chronic gastritis clearly related to a bacterium . The inflammation often is severe and commonly damages the mucosa, with ulceration, atrophy, metaplasia, and occasional premalignant changes . Physicians would treat inflammation of this degree in most other parts of the body . This disease is usually symptomless . There is some controversy, but eradicating Helicobacter often fails to improve nonulcer dyspepsia . This failure results in a continuing argument over whether or not to treat the infection . Meanwhile the pathology continues . A temporary solution to the problem is suggested: Patients infected with Helicobacter can give informed consent . Patients can be told about the infection, the pathology, the poor relationship to symptoms, and side effects of therapy, and they can decide.

Gastroenterol Clin North Am, 2000 Sep, 29(3), 649 - 70
Virulence and pathogenicity of Helicobacter pylori; Go MF et al.; Bacterial and host response factors play significant roles in the pathogenicity of H . pylori-related disease manifestations . The complete DNA sequences for two H . pylori strain genomes have been published . The differences in the sequences between these two unrelated strains may enable clinicians to identify rapidly other conserved and potentially virulent genes and products . Whether these two DNA sequences are sufficient representation of the H . pylori genetic heterogeneity is unknown . The host immune response and the cascade of events that occurs with H . pylori infection are being clarified rapidly . Understanding the role of this gastric bacterium in apoptosis and cellular proliferation would enable clinicians to understand its relationship to ulcerogenesis and gastric malignancy . Piecing together many observations related to H . pylori would result in understanding the interaction of H . pylori factors and host responses that lead to the variety of disease manifestations associated with this chronic infection . The development of animal models with H . pylori and other Helicobacter species has set the stage in which in vitro observations can be tested in the in vivo model.

J Invertebr Pathol, 2000 Aug, 76(2), 95 - 104
Ultrastructure and cytopathology of a rickettsia-like organism causing systemic infection in the redclaw crayfish, Cherax quadricarinatus (Crustacea: decapoda), in Ecuador; Romero X et al.; A study of the ultrastructural characteristics of an intracellular bacterium infecting the redclaw crayfish, Cherax quadricarinatus, a pathogen referred to previously as a rickettsia-like organism (RLO), revealed the presence of different developmental stages . These included a rod-shaped and uniformly electron-dense elementary body (EB) and an intermediate body (IB) . The length of the EB varied between 0.48 and 0.6 microm, and the diameter was 0.3 microm . The IB was 0.75 to 1.1 microm long by 0.36 to 0.44 microm in diameter . Although the EB of this bacterium has ultrastructural characteristics similar to those of Rickettsiella, no information is available regarding its genetic relationship to this genus, and the intracellular bacterium should continue to be referred to as a rickettsia-like organism . The hemocytes had different levels of infection, and the RLO proliferated inside these cells . The EB appeared to be free in the cytoplasm of infected hemocytes and other cells; however, this might be a fixation artifact . The EB was also contained in membrane-bound vacuoles along with the IB . RLO colonies were observed inside small granular cells . No large granular cells were observed in the sections examined; therefore, no data were obtained regarding infection of this type of hemocyte . The fixed phagocytes on the external side of the terminal hepatic arterioles had an activated interrupted layer containing RLO bacteria . Stem cells in the hematopoietic tissue were also infected, and some cells were apparently being released into circulation .

Virus Genes, 2000, 21(1-2), 7 - 12
Evolution of viruses by acquisition of cellular RNA or DNA nucleotide sequences and genes: an introduction; Becker Y; The origins of virus evolution may be traced to Archeabacteria since Inouye and Inouye (6) discovered a retroelement with a gene for reverse transcriptase in the bacterial genome and in the satellite, multiple copy single stranded DNA (msDNA) in the soil bacterium Myxococcus xanthus . It was possible (8) to define the evolution of retroelements in eukaryotic cells of plants, insects (gypsy retrovirus) and vertebrates . The replication of RNA viruses in eukaryotic cells allowed for the viral RNA genome to integrate a cellular ubiquitin mRNA, as reported for BVDV (24) . Another example is the integration of 28S ribosomal RNA into the hemagglutinin gene of an influenza virus . This change in the hemagglutinin gene led to an increased pathogenicity of the influenza virus (25) . In contrast to RNA viruses, DNA viruses had evolved by inserting cDNA molecules derived from mRNA transcripts of cellular genes or foreign viral RNA . It is of interest that the virus acquired cellular genes in the genomes of DNA viruses represent genes that code for proteins that inhibit cellular molecular processes related to HLA class I and II molecules . The other acquired genes are cellular genes that code for cytokines that are capable of inhibiting antigen presentation to T cells by antigen presenting cells (APC) by dendritic Langerhans cells . The acquisition of cellular genes by DNA viruses enhances their pathogenicity by inhibiting the hosts' defense systems.

Clin Chim Acta, 2000 Nov, 301(1-2), 181 - 92
N alpha-methylhistamine: association with Helicobacter pylori infection in humans and effects on gastric acid secretion; Murray S et al.; Infection with the bacterium Helicobacter pylori is associated with altered gastric acid secretion and gastrointestinal disease . Recent work has suggested that N alpha-methylhistamine, produced by the bacterium and acting on histamine receptors in gastric tissue, might be involved . Gastric juice and tissue biopsies from infected patients have been analysed for the presence of N alpha-methylhistamine using a specific and sensitive assay based on gas chromatography mass spectrometry . N alpha-Methylhistamine was detected in five of seven samples of gastric juice from infected patients (5-180 pmol/ml) but was absent in nine uninfected subjects . The compound was not found in fundic and antral biopsies from both subject groups . Helicobacter pylori, cultured on agar and in broth with and without added histamine, was found not to produce detectable levels of N alpha-methylhistamine . Instillation of this compound at 10(-5) mol/l into the gastric lumen produced a significant increase in acid secretion in vivo while plasma gastrin concentration remained unchanged . N alpha-Methylhistamine in gastric juice appears therefore to be associated with infection, although this product is not generated directly by the bacterium . The concentrations found are below those required to affect acid secretion or gastrin production in vivo, although higher local concentrations may exist around a site of infection.

Rev Prat, 2000 Sep 1, 50(13), 1437 - 41
{Helicobacter pylori infection in children}; Dupont C et al.; Helicobacter pylori infection is frequent in children . Its incidence in Europe, around 6% in children aged 6-16 years, varies with the socio-economic level and nutritional status . It may reach 46% in Africa and up to 75% in some institutions . Clinical manifestations debated . Vomiting, dyspepsia and acute pain related to ulcer disease may undisputedly be linked to H . pylori, whereas its role in chronic abdominal has yielded contradictory reports . Direct isolation of the bacterium is classically done through perendoscopic antral biopsies followed by culture and histology . Non-invasive diagnosis methods get a wider use in children . Serodiagnosis is reproducible and easy only in older children . The 13C-urea breath test is sensitive and specific, and seems perfectly suitable in pediatrics . The H . pylori stool antigen test for the detection of infection seems promising but not yet of current clinical use . Triple therapy using amoxicillin-clarithromycin (or metronidazole or tinidazole) and anti-secretory agents is recognised as the most efficient association.

What Is Growth Medium?, What Is Bioengineering?, What Is Protein?, What Is Environmental Microbiology?, What Is Listeria Monocytogenes?, s, Bacterium, r, Microbes, r, Microbe, s, Bacteria, i, Microorganism, s, Streptomycin, a, Fermentations, n, Staphylococcus, e, Pseudomonas aeruginosa, r, Bacteria, o, Schizosaccharomyces, a, Salmonella, s, Salmonella typhimurium, c, Streptococci, c, Paracocci, c, Clostridia, c, Escherichia coli, s, Microorganism, r, Antimicrobial, s, Cholera, e, Erythromycin, s, Salmonella, s, Staphylococcus aureus, n, S. cerevisiae, n, Bacteria, e, Antibiotics

Scientific Publications - Work Done by Microbiology Reader Bioscreen C
Agricultural Microbiology Anaerobic Microbiology Antimicrobial Susceptibility Artificial Atmosphere Bioassay of Antibiotics Biofilm Microbiology Bioreactor Technology Biotechnology Cell Biology Clinical Microbiology Environmental Microbiology Experiments with Yeast	Fermentation Food Microbiology Functional Genomics Gene Technology Growth Media Development Growth Rate and Lag Time Industrial Microbiology Medical/Pharmaceutical Field Microbiological Assay Microbiological Research Microbiology of Cosmetics go to a specific theme...	Military Microbiology Molecular Microbiology Mutagenicity and Genotoxicity Oral Microbiology Patents Postantibiotic Studies Soil Microbiology Spore Microbiology Veterinary Microbiology Waste/Wastewater Treatment Water Microbiology Wine Microbiology

� 2005 Transgalactic Ltd (manufacturer of Bioscreen C software) | Privacy Statement | P.O. Box 1393, 00101 Helsinki, Finland, phone: +358 9 85172920, fax: +358 9 8749481, e-mail: microbiology@bionewsonline.com

Last modified: May 25, 2005