Bacteria

Peptides, 1997, 18(9), 1295 - 9
Expression of rat pro cholecystokinin (CCK) in bacteria and in insect cells infected with recombinant baculovirus; Wang W et al.; Neuropeptide prohormones are generally not abundant in nature as they exits to be processed and contain sites which could be cleaved by a number of cellular proteases . In order to study the processing of prohormones in vitro it is necessary to produce them in quantity . Finding an expression system which produces intact prohormone has been a matter of trial and error . We report that intact rat pro CCK was produced with an amino-terminal His-Tag in e . coli, and it was secreted from sf9 and other insect cells infected with a recombinant baculovirus vector . The bacteria contained about 0.1 micrograms pro CCK/ml of cells . The High 5 insect cells produced 4.3 micrograms/ml medium (as determined by RIA), 10 times as much as sf9 or sf21 . Using a combination of ion exchange, gel filtration and HPLC, the insect cell protein was purified about 150 fold with a recovery of about 16% . The secreted insect cell pro CCK is tyrosine sulfated like its mammalian equivalent . Using these expression systems it is possible to produce significant (microgram to mg) quantities of pro CCK for immunologic, enzymatic and structural studies.

Nature, 1997 Nov 27, 390(6658), 395 - 8
Test of synergistic interactions among deleterious mutations in bacteria; Elena SF et al.; Identifying the forces responsible for the origin and maintenance of sexuality remains one of the greatest unsolved problems in biology . The mutational deterministic hypothesis postulates that sex is an adaptation that allows deleterious mutations to be purged from the genome; it requires synergistic interactions, which means that two mutations would be more harmful together than expected from their separate effects . We generated 225 genotypes of Escherichia coli carrying one, two or three successive mutations and measured their fitness relative to an unmutated competitor . The relationship between mutation number and average fitness is nearly log-linear . We also constructed 27 recombinant genotypes having pairs of mutations whose separate and combined effects on fitness were determined . Several pairs exhibit significant interactions for fitness, but they are antagonistic as often as they are synergistic . These results do not support the mutational deterministic hypothesis for the evolution of sex.

Curr Opin Genet Dev, 1997 Oct, 7(5), 582 - 8
Adaptation of gene expression in stationary phase bacteria; Ishihama A; In nature, bacteria can survive for long periods in non-growing stationary states . Some species of bacteria survive by forming spores but non-spore-forming bacteria, including Escherichia coli, survive in the stationary phase . Gross changes in morphology and physiology occur in the stationary-phase bacteria and concomitantly a state of increased resistance against various stresses is established . The stationary-phase adaptation of E . coli has only recently begun to be investigated at the molecular level.

Zhonghua Wai Ke Za Zhi, 1996 Apr, 34(4), 201 - 4
{Extremity gangrene caused by rare co-infection of multiple bacteria: a case report}; Liu S et al.; Because of progressive infectious necrosis on right hand and forearm for 3 months and the necrosis on left mid-finger for 2 months, a girl patient, Yang Xiaoxia was admitted on 15th, Nov . 1994 . Systemic intoxicative symptom was slight and the necrotic tissue presented black scar . After 3 months treatment by application of multiple antibiotics, local dressing changes and an amputation of right froearm, the necrosis could not be stopped but keeping deteriorating . Through experts' consultation, systemic surpportive therapy, wide-spectrum antibiotics cilastatin sodium and complete debridement were adopted . One week later, the fresh surface of granulation tissue was seen, and skin grafting was performed . The wound healed 3 months later . After further rehabilitation, the left thumb, index and fifth finger showed normal function . A mechanical motional artificial limb was installed on right forearm and discharged . The deep necrotic tissue of left mid-finger was examined . Results of culture from several hospital presented 2 kinds of aerobic bacteria and 10 kinds of the anaerobic, of which, the names of 3 kinds are still unknown . Pathological examination showed chronic pyogenic necrotic infection, spreading from skin to deep muscles and interosseous membrane . And infiltration of eosinophilic granulocytes was found in the infectious region . CONCLUSION: This patients is progressive gangrene of the extremity caused by rare co-infection of multiple bacteria . The characteristics were slight systemic intoxicative symptom, local progressive necrosis and formation of black scar . By means of systemic surpportive therapy, application of wide-spectrum antibiotics cilastatin sodium, complete debridement and skin grafting, the patient was cured.

Biochem Biophys Res Commun, 1997 Oct 29, 239(3), 769 - 74
A molecular aspect of symbiotic interactions between the weevil Sitophilus oryzae and its endosymbiotic bacteria: over-expression of a chaperonin; Charles H et al.; Specific proteins of symbiosis were analyzed by the comparison of two-dimensional electrophoresis protein patterns of symbiotic and aposymbiotic strains of the weevil Sitophilus oryzae . One protein was shown to be exclusively expressed in the aposymbiotic strain and three proteins, including a chaperonin, were characterized in the symbiotic strain pattern . The groE-like operon, encoding the two chaperonins groES and GroEL-like proteins of the endocytobiotes, was sequenced . It was found to be very similar to the groE operon of Escherichia coli (82% identity) . In vitro and ex vivo experiments of protein labelling demonstrated that almost 40% of the endocytobiote protein synthesis ex vivo is focused on the GroEL-like protein . Finally, we showed by northern blotting that heat shock at 38 degrees C results in groEL mRNA accumulation inside the endocytobiotes . This work supports the hypothesis that chaperonins could have an essential physiological function in the maintenance of the symbiotic association.

Appl Environ Microbiol, 1997 Nov, 63(11), 4237 - 42
Numerical dominance of a group of marine bacteria in the alpha-subclass of the class Proteobacteria in coastal seawater; Gonzalez JM et al.; A cluster of marine bacteria within the alpha-3 subclass of the class Proteobacteria accounted for up to 28% of the 16S ribosomal DNA (rDNA) sequences in seawater samples from the coast of the southeastern United States . Two independent oligonucleotide probes targeting 16S rDNA of this "marine alpha" cluster indicate that the group dominates bacterioplankton communities in estuarine and nearshore regions of the southeastern U.S . coast . Marine alpha bacteria decline predictably in abundance with decreasing salinity along estuarine transsects and are not detectable in low-salinity (5%) or freshwater samples . Sequences of 16S rDNA obtained from seawater by PCR with one group-specific oligonucleotide as a primer confirm that the oligonucleotide targets only members of this phylogenetic cluster . Likewise, sequences of 16S rDNA obtained from seawater by PCR with several different pairs of nonspecific primers show an unusually high abundance of marine alpha sequences (52 to 84%) among the clones, which possibly indicates a PCR bias toward the group . Members of the marine alpha group were readily cultured from coastal seawater, accounting for 40% of the colonies isolated on low-nutrient marine agar, based on hybridizations with the group-specific 16S rDNA probe and on sequence analysis . This is the first description of a numerically dominant cluster of coastal bacteria, identified by molecular techniques, that can be readily cultured and studied in the laboratory.

J Bacteriol, 1997 Nov, 179(21), 6764 - 8
Photoresponses of the purple nonsulfur bacteria Rhodospirillum centenum and Rhodobacter sphaeroides; Sackett MJ et al.; We have measured the photoresponse of two purple nonsulfur bacteria, Rhodobacter sphaeroides and Rhodospirillum centenum, under defined conditions in a light beam propagating at 90 degrees to the optical axis of the microscope . This beam presented cells with a steep gradient of intensity perpendicular to the direction of propagation and a shallow gradient in the direction of light propagation . R . centenum, a species that reverses to change direction, accumulated in the light beam, as expected for a "scotophobic" response, while R . sphaeroides, which stops rather than reverses, accumulated outside the light beam . We also compared the behavior of liquid-grown R . centenum, which swims by using a single polar flagellum, to that of surface-grown R . centenum, which swarms over agar by using many lateral flagella and has been shown to move as colonies toward specific wavelengths of light . When suspended in liquid medium, both liquid- and surface-grown R . centenum showed similar responses to the light gradient . In all cases, free-swimming cells responded to the steep gradient of intensity but not to the shallow gradient, indicating they cannot sense the direction of light propagation but only its intensity . In a control experiment, the known phototactic alga Chlamydamonas reinhardtii was shown to swim in the direction of light propagation.

J Comp Pathol, 1997 Aug, 117(2), 185 - 90
Segmented filamentous bacteria in the bovine small intestine; Smith TM; Segmented filamentous bacteria (SFB) were observed in a 28-day-old calf, attached to the absorptive villi . Morphologically, they were similar to SFB described in other animal species . Because these organisms cannot be cultured, further characterization was not possible . The organisms were confined to the upper third of the absorptive villi and were not seen attached to the follicle-associated epithelium of the Peyer's patch, or observed in the caecum or colon . Although they were often associated with minor lesions, their pathological significance was doubtful . With this report, segmented filamentous bacteria have now been described in virtually all the commercially important livestock and poultry species, in other domestic animals, and in man.

J Appl Microbiol, 1997 Oct, 83(4), 518 - 23
A quantitative PCR-ELISA for the rapid enumeration of bacteria in refrigerated raw milk; Gutierrez R et al.; We have developed a quantitative PCR-ELISA for the rapid enumeration of bacteria in refrigerated raw milk using primers designed from conserved regions in the 16S ribosomal RNA gene (rRNA) . The designed primers permitted the amplification of a 147 bp DNA fragment from a wide selection of bacteria which may grow in milk at refrigeration temperatures . Amplified PCR products generated using a digoxigenin-labelled primer were heat-denatured before being quantified by an enzyme-linked immunosorbent assay (ELISA) . A biotinylated probe immobilized onto streptavidin-coated microplates was used to capture the digoxigenin-labelled fragments that were detected with a peroxidase anti-digoxigenin conjugate . Subsequent enzymic conversion of substrate gave distinct absorbency differences when assaying milk samples containing bacteria in the range 10(3)-10(7) cfu ml-1 . The detection threshold for the PCR-ELISA assay developed in this work is 103 cfu ml-1.

J Appl Microbiol, 1997 Oct, 83(4), 421 - 9
Diversity among aromatic hydrocarbon-degrading bacteria and their meta-cleavage genes; Daly K et al.; Sixty-one strains of bacteria capable of growth on 4-methyl benzoic acid (29 isolates) or naphthalene (32 isolates) as the sole source of carbon and energy were isolated from sediments and water samples from the River Tyne, UK . Random amplification of polymorphic DNA from genomic DNA extracted from the different strains demonstrated that 14 of the 4-methyl benzoate-degrading isolates were unique and the remainder fell into seven groups containing two or three isolates that produced identical banding patterns . Thirteen of the naphthalene-degrading isolates were unique and nine groups with two or three identical representatives encompassed all other isolates . Screening of the bacterial strains for the presence of genes homologous to xylE, nahC and bphC by polymerase chain reaction and dot blot hybridization demonstrated that most strains harboured xylE- and/or nahC-like genes and only a single isolate was found that did not harbour any of these genes . None of the isolates harboured bphC-like genes . It was concluded that, while considerable diversity existed in host strains isolated using a single simple enrichment procedure, the extradiol dioxygenase genes involved in aromatic ring cleavage, present in these strains, were conserved to a considerable degree.

Exp Cell Res, 1997 Oct 10, 236(1), 43 - 50
Autofluorescence of live purple bacteria in the near infrared; Albrecht-Buehler G; We have developed a novel microscope with which to study the fluorescence of cells in the near-infrared region (lambda = 750-2500 nm) . For one of its first applications we report on the autofluorescence of live purple bacteria, Rhodospirillum rubrum, and suggest that the autofluorescent component is bacteriochlorophyll . The rapid fading of the autofluorescence of fixed bacteria and of purified bacteriochlorophyll suggests that the live bacteria are able to regenerate their pigment with a time constant of approximately 20 s.

J Biol Chem, 1997 Oct 10, 272(41), 25623 - 7
A component of the chloroplast protein import apparatus functions in bacteria; Pang P et al.; Toc36 is a family of 44-kDa envelope polypeptides previously identified as components of the chloroplast protein import apparatus by virtue of their close physical proximity to translocating proteins . An indication of their function thus remains at large . A heterologous in vivo approach for studying the function of Toc36 was developed in this study by introducing a member of Toc36 into E . coli to assess its effect on bacterial protein translocation . The presence of Toc36 enhances the translocation of two bacterial periplasmic proteins in a manner resembling the chloroplast system . Translocation of the two bacterial periplasmic proteins was less sensitive to sodium azide, resembling more the azide-insensitive nature of the chloroplast protein import process . Mutated Toc36 proteins were not capable of causing the same effect as that observed for unaltered Toc36 . Toc36 was also capable of complementing bacterial strains with temperature-sensitive secA mutations that affected protein translocation . The combined results provide evidence that Toc36 plays a central role in the chloroplast protein translocation process.

J Mol Biol, 1997 Sep 26, 272(3), 301 - 11
Characterization of nucleosome core particles containing histone proteins made in bacteria; Luger K et al.; The four core histone proteins, H2A, H2B, H3, and H4 of Xenopus laevis have been individually expressed in milligram quantities in Escherichia coli . The full-length proteins and the "trypsin-resistant" globular domains were purified under denaturing conditions and folded into histone octamers . Both intact and truncated recombinant octamers, as well as chicken erythrocyte octamer, were assembled into nucleosome core particles using a 146 bp defined-sequence DNA fragment from a 5 S RNA gene . The three types of core particles were characterized and compared by gel electrophoresis, DNase I cleavage, and tyrosine fluorescence emission during stepwise dissociation with increasing ionic strength . Nucleosome core particles containing native and mutant histones made in bacteria have facilitated its X-ray structure determination at 2.8 A resolution .

Vestn Ross Akad Med Nauk, 1997, (7), 8 - 13
{Theoretical rationale for structure-genotoxicity relationships in the series of halogenated short-chain aliphatic compounds for mammals and bacteria}; Kharchevnikova NV et al.; Structure-genotoxicity relationships for mammals and structure-mutagenic activity relationships for bacterial were derived in the series of halogenated short-chain hydrocarbons and alcohols, by using the calculated quantum chemical parameters, namely the energy differences of frontier molecular orbitals and the electronic characteristics of the probable metabolites.

Biosci Rep, 1997 Jun, 17(3), 335 - 42
How do bacteria avoid high oxygen concentrations?
Zhulin IB, Johnson MS, Taylor BL.
Bacteria, such as Escherichia coli and Azospirillum brasilense, avoid microenvironments with elevated oxygen concentrations, not by sensing reactive oxygen derivatives, but by sensing a metabolic down-shift that results from elevated oxygen levels . A novel protein, Aer, and the chemotaxis serine receptor, Tsr, have recently been identified as transducers for aerotaxis which monitor internal energy levels in the bacteria.

Biotechnol Prog, 1997 Sep-Oct, 13(5), 519 - 23
Acetate-specific stress response in acetate-resistant bacteria: an analysis of protein patterns; Lasko DR et al.; Many metabolic byproducts have toxic effects on bacteria, and acetic acid is an excellent model for such molecules . The negative effects of acetate, which include decreased growth rates and specific productivities, appear for Escherichia coli at acetate concentrations lower than 5 g/L . Acetic acid bacteria, however, are naturally resistant to the detrimental effects of acetate in their surroundings; they remain active at acetate levels well over 40 g/L . This study investigated the response to acetate challenges by the naturally acetate-resistant bacteria Acetobacter aceti and Gluconobacter suboxydans to learn more about possible mechanisms of tolerance to otherwise toxic low molecular weight metabolites . Growth studies showed that the resistant bacteria grow more slowly in the presence of acetate but are not slowed nearly so much as is E . coli . In addition, two-dimensional gel electrophoresis (2DE) was applied to study the relative protein patterns of acetate-resistant bacteria during growth in the presence and absence of acetate . In each organism, growth in acetate-containing medium led to elevated levels of many stress response proteins . 2DE analysis of heat-shocked cultures was used to determine which were nonspecific . Elimination of those proteins that were also amplified following heat shock left only eight proteins, here designated acetate-specific stress proteins (Asps), which are overexpressed specifically in response to acetate . Three of these, AspA, AspB, and AspC, appear to be analogous in the two bacterial strains studied, based on their apparent pIs and molecular weights.

Infect Immun, 1997 Oct, 65(10), 4243 - 9
Involvement of p21racA, phosphoinositide 3-kinase, and vacuolar ATPase in phagocytosis of bacteria and erythrocytes by Entamoeba histolytica: suggestive evidence for coincidental evolution of amebic invasiveness; Ghosh SK et al.; Trophozoites of Entamoeba histolytica, the protozoan parasite that causes amebic dysentery, phagocytose bacteria in the colonic lumen and erythrocytes (RBC) in host tissues . Because tissue invasion is an evolutionary dead end, it is likely that amebic pathogenicity is coincidentally selected, i.e., the same methods used to kill bacteria in the colonic lumen are used by parasites to damage host cells and cause disease . In support of this idea, the amebic lectin and pore-forming peptide are involved in binding and killing, respectively, bacteria and host epithelial cells . Here amebic phagocytosis of bacteria, RBC, and mucin-coated beads was disrupted by overexpression of E . histolytica p21(racA-V12), a ras-family protein involved in selection of sites of actin polymerization, which had been mutated to eliminate its GTPase activity . p21(racA-V12) transformants were also defective in capping and cytokinesis, while pinocytosis of fluorescent dextrans was not affected . Wortmannin, a fungal inhibitor of phosphoinositide 3-kinase, markedly inhibited phagocytosis of bacteria, RBC, and mucin-coated beads by wild-type amebae . In contrast to p21(racA-V12) overexpression, wortmannin abolished amebic pinocytosis of dextrans but had no inhibitory effects on capping . Inhibition of amebic vacuolar acidification by bafilomycin also decreased bacterial and RBC uptake . These results, which demonstrate similarities between mechanisms of phagocytosis of bacteria and RBC by amebae and macrophages, support the idea of coincidental selection of amebic genes encoding proteins that mediate destruction of host cells.

Arch Biochem Biophys, 1997 Sep 15, 345(2), 223 - 9
Direct evidence for a soluble methane monooxygenase from type I methanotrophic bacteria: purification and properties of a soluble methane monooxygenase from Methylomonas sp . GYJ3; Shen R et al.; The hydroxylase and reductase components of a soluble methane monooxygenase from type I methanotrophs--Methylomonas sp . GYJ3--were purified by a multiple-step LC procedure . The hydroxylase (approximately 240 kDa, determined by an HPLC-size exclusion chromatography method) has three subunits with molecular masses of 56, 43, and 27 kDa, suggesting that the enzyme has an (alphabeta gamma)2 subunit structure . The HPLC method was developed to purify the hydroxylase component, and the purified protein has a specific activity of 541 nmol propene oxide x mg(-1) protein x min(-1), which is two times the specific activity of the protein purified by the two-step LC procedure . The iron content in the hydroxylase purified by the two-step LC procedure is 2.1 mol of Fe per mole of protein, but the iron content in the protein by the HPLC procedure is 3.78 mol of Fe per mole of protein . The diversity of iron contents in this protein is due mainly to the use of different purification methods . The reductase has a molecular mass of 42 kDa . The UV-VIS spectrum of the protein is similar to that of proteins from other methanotrophs, suggesting that the protein contains a FAD cofactor and a {2Fe-2S} center . The partially purified component B stimulated the MMO activity of the hydroxylase and reductase system by 40-fold.

Gene, 1997 Aug 22, 195(2), 257 - 66
Three insertion sequences from the cyanobacterium Synechocystis PCC6803 support the occurrence of horizontal DNA transfer among bacteria; Cassier-Chauvat C et al.; Three insertion sequences were characterized from the widely-used cyanobacterium Synechocystis PCC6803 . They all harbored a putative transposase sequence flanked by two imperfect inverted repeats, seemed to have duplicated their target insertion site and occurred as multiple copies in the host genome . They exhibited no obvious homology with any other cyanobacterial ISs and were termed IS5S (871 bp), IS4S (1299 bp) and ISS1987 (949 bp) because they were, respectively, homologous to IS5- and IS4-bacterial elements, and to several members of the IS630-Tc1-mariner superfamily of IS elements occurring in a wide range of hosts . This suggests that these IS-elements were spread through horizontal transfer between evolutionary distant organisms . Three IS5S-copies were isolated as a rescue insertion into a replicating plasmid (IS5Sa), or subsequently cloned from a Synechocystis DNA-library probed with IS5Sa (IS5Sb and IS5Sc), and appeared to be almost identical . In the vicinity of IS5Sb, we found the ISS1987 element inserted into the IS4S element . This indicates that the ISS1987 element has been, and could still be, mobile since its transposase sequence is not interrupted with stop codons or translational frameshifts, unlike that which is found in most members of the IS630-Tc1-mariner superfamily of transposable elements.

Zhonghua Hu Li Za Zhi, 1997 Mar, 32(3), 132 - 4
{Analysis of influential factors of suspended bacteria in air in operating rooms}; Ma ZY et al.; In order to control the air borne bacterial contamination of operation in operating rooms, we designed to do air sampling with FA-1 suspending air bacterial particle sampling kits . Samples were from purified operating rooms and nonpurified operating rooms, aseptic operation and contaminated operation . Data were collected in 7 different stages and 3 different altitudes . Data were statistically analysed by means of logistic linear model . The results help us understand the influencing factors of air contamination . Strategies of control of those factors were discussed.

Biosci Biotechnol Biochem, 1997 Aug, 61(8), 1244 - 51
The phylogeny of acetic acid bacteria based on the partial sequences of 16S ribosomal RNA: the elevation of the subgenus Gluconoacetobacter to the generic level; Yamada Y et al.; Thirty-six strains of acetic acid bacteria classified in the genera Acetobacter, Gluconobacter, and Acidomonas were examined for their partial base sequences in positions 1220 through 1375, 156 bases, of 16S rRNA . The strains of the Q10-equipped Gluconobacter species examined were divided into two subgroups, which included the type strains of Gluconobacter oxydans, the type species of the genus Gluconobacter, and of a second species, Gluconobacter cerinus, respectively . The base differences numbered four between the two type strains . The strains of the Q9-equipped species examined classified in the type subgenus Acetobacter of the genus Acetobacter were not very distant phylogenetically from those of the genus Gluconobacter . The calculated number of base differences was 9-6 between the type strains of G . oxydans and G . cerinus and the type strains of Acetobacter aceti and Acetobacter pasteurianus . In contrast, the strains of the Q10-equipped species examined classified in the subgenus Gluconoacetobacter of the genus Acetobacter were very distant phylogenetically from those of the Acetobacter and Gluconobacter species mentioned above . The number of base differences was calculated to be 14-8 . Furthermore, the strains of the methanol-assimilating, Q10-equipped species of the genus Acidomonas examined were located in phylogenetically isolated positions . The type strain of Acidomonas methanolica (identical to Acetobacter methanolicus), the type species of the genus Acidomonas, had 16-9 base differences . The data obtained here indicated that the members of the subgenus Gluconoacetobacter of the genus Acetobacter can be distinguished at the generic level . The new genus Gluconoacetobacter was proposed with the type species, Gluconoacetobacter liquefaciens, in recognition of the genus Acidomonas along with the genera Acetobacter and Gluconobacter in the classification of the acetic acid bacteria.

Biotechniques, 1997 Sep, 23(3), 494 - 8
One primer pair amplifies small subunit ribosomal DNA from mitochondria, plastids and bacteria . Mitochondria, plastids and bacteria; Berschick P; A pair of PCR primers, directed towards conserved regions of small ribosomal subunit RNA (SSU rRNA) genes, was used to amplify segments of animal and plant mtDNA, chloroplast DNA and bacterial DNA by PCR . PCR products of animal, plant and bacterial DNA differ in length, enabling separation for an "individual" sequence analysis . Using this technique, it was found that preparations of the body wall muscle and of mitochondria from the lugworm Arenicola marina used for physiological studies contain significant amounts of bacterial DNA . Since the use of these primers seems not to be taxonomically restricted, it offers new opportunities for phylogenetic and population research.

J Am Dent Assoc, 1997 Sep, 128(9), 1263 - 71
Can one acquire periodontal bacteria and periodontitis from a family member?
Asikainen S, Chen C, Alaluusua S, Slots J.
Recent findings suggest that two major periodontal pathogenes, Actinobacillus actinomycetemcomitans and Porphyromonas gingivalis, are transmitted among family members . The authors discuss the evidence of person-to-person transmission of periodontal bacteria, the significance of saliva as a vehicle of transmission and the methods of verifying clonal similarity of bacterial strains obtained from family members . The authors also discuss the prophylactic and therapeutic implications of the person-to-person spread of periodontal bacteria.

Arch Microbiol, 1997 Oct, 168(4), 249 - 61
Behavioural responses of bacteria to light and oxygen; Armitage JP; Motile bacteria have long been known to swim towards or away from specific environmental stimuli such as nutrients, oxygen or light . Although there has been a detailed description of chemosensory responses in enteric species for several years, there has been little information on the mechanisms involved in responses to stimuli affecting electron transport as these usually also change the electrochemical proton gradient - at least transiently - and, thus, directly change flagellar rotation . There have, however, been major advances recently . Halobacterium salinarium uses a retinal-based sensory system to sense changes in specific wavelengths of light and to signal via a transmembrane sensory protein, which turns out to be homologous to the transmembrane chemoreceptors of Escherichia coli . A FAD-binding protein, also related to these receptors, signals changes in respiratory electron transport in E . coli . Rhodobacter sphaeroides cells do not respond to light or oxygen specifically, but sense a change in the rate of electron transfer, probably again using an electron-transport-chain-linked redox sensor, signalling through a common sensory pathway . These recent studies reveal that bacteria not only sense a range of environmental stimuli but also integrate the signals through common pathways to produce a balanced flagellar response.

Antonie Van Leeuwenhoek, 1997 Jul, 72(1), 29 - 38
Verrucomicrobia div . nov., a new division of the bacteria containing three new species of Prosthecobacter; Hedlund BP et al.; Four strains of nonmotile, prosthecate bacteria were isolated in the 1970s and assigned to the genus Prosthecobacter . These strains were compared genotypically by DNA/DNA reassociation and 16S rDNA based phylogenetic analyses . Genotypic comparisons were complemented with phenotypic characterizations . Together, these studies clearly indicate each Prosthecobacter strain represents a novel species of bacteria . We propose three new species of Prosthecobacter, P . dejongeii strain FC1, P . vanneervenii strain FC2, and P . debontii strain FC3; P . fusiformis is reserved for the type strain of the genus, strain FC4 . Additionally, we propose the genera Prosthecobacter and Verrucomicrobium, currently members of the order Verrucomicrobiales, to comprise a novel higher order taxonomic group, the division Verrucomicrobia div . nov . and the class Verrumicrobiae class nov . Many novel members of the Verrucomicrobia, as revealed by molecular ecology studies, await isolation and description.

Microbiol Mol Biol Rev, 1997 Sep, 61(3), 337 - 76
Biogenesis of respiratory cytochromes in bacteria; Thony-Meyer L; Biogenesis of respiratory cytochromes is defined as consisting of the posttranslational processes that are necessary to assemble apoprotein, heme, and sometimes additional cofactors into mature enzyme complexes with electron transfer functions . Different biochemical reactions take place during maturation: (i) targeting of the apoprotein to or through the cytoplasmic membrane to its subcellular destination; (ii) proteolytic processing of precursor forms; (iii) assembly of subunits in the membrane and oligomerization; (iv) translocation and/or modification of heme and covalent or noncovalent binding to the protein moiety; (v) transport, processing, and incorporation of other cofactors; and (vi) folding and stabilization of the protein . These steps are discussed for the maturation of different oxidoreductase complexes, and they are arranged in a linear pathway to best account for experimental findings from studies concerning cytochrome biogenesis . The example of the best-studied case, i.e., maturation of cytochrome c, appears to consist of a pathway that requires at least nine specific genes and more general cellular functions such as protein secretion or the control of the redox state in the periplasm . Covalent attachment of heme appears to be enzyme catalyzed and takes place in the periplasm after translocation of the precursor through the membrane . The genetic characterization and the putative biochemical functions of cytochrome c-specific maturation proteins suggest that they may be organized in a membrane-bound maturase complex . Formation of the multisubunit cytochrome bc, complex and several terminal oxidases of the bo3, bd, aa3, and cbb3 types is discussed in detail, and models for linear maturation pathways are proposed wherever possible.

Appl Environ Microbiol, 1997 Sep, 63(9), 3359 - 66
Dominant marine bacterioplankton species found among colony-forming bacteria; Pinhassi J et al.; The density of specific aquatic bacteria was determined by use of whole-genome DNA hybridization towards community DNA . From a coastal marine environment (northern Baltic Sea), 48 specific bacteria were isolated on solid media over a 1-year period . Based on the presented hybridization protocol, the total density of the isolates ranged between 7 and 69% of the bacteria determined by acridine orange direct counts . When compared to the number of nucleoid-containing cells, the range increased to 29 to 111% . Thus, our results showed that bacteria able to form colonies on solid media accounted for a large fraction of the bacterioplankton . There were significant changes in the density of the different bacteria over the year, suggesting that bacterioplankton exhibit a seasonal succession analogous to phytoplankton . The bacteria studied were of diverse phylogenetic origin, being distributed among the alpha, beta, and gamma subdivisions of the class Proteobacteria and the cytophaga-flexibacter group . Partial 16S rRNA gene sequence analysis of 29 Baltic Sea isolates as well as of 30 Southern California Bight isolates showed that a majority of the isolates had low similarity (0.85 to 0.95) to reported sequence data . This indicated that the diversity of marine bacteria able to grow on solid media is largely unexplored.

Mol Mar Biol Biotechnol, 1997 Sep, 6(3), 260 - 7
Ribosomal RNA gene dosage in marine bacteria; Kerkhof L et al.; Ribosomal RNA gene dosage was determined for 20 marine heterotrophic bacteria using short probes (< 600 bp) from the Escherichia coli 16S rRNA gene and Southern blot analysis . All Bacterial strains had between 4 and 10 copies of the 16S rRNA genes in their genomes . This report presents important preliminary data for developing quantitative molecular methods to address population dynamics of marine based of 16S rRNA sequences.

Mol Mar Biol Biotechnol, 1997 Sep, 6(3), 238 - 47
Alteration in plasmid DNA following natural transformation to populations of marine bacteria; Williams HG et al.; This article examines alterations in a broad-host-range plasmid (pQSR50) that were observed following transfer to indigenous marine bacteria by natural transformation . Plasmid DNA from the transformants had altered restriction profiles . However, with the exception of the EcoRI site from one transformant (BS10), fragments amplified by polymerase chain reaction (PCR) and encompassing the recognition sites were cleaved by the relevant endonucleases, providing the sites were present . Analysis with DpnI and MboI indicated differences in DNA methylation between pQSR50 and the transformants . The missing EcoRI site from BS10 and smaller EcoRI fragments observed in transformants indicated that rearrangements had also occurred . Evolution of novel plasmid molecules following gene transfer may be an important mechanism by which natural genetic diversity is generated.

Biophys J, 1997 Aug, 73(2), 994 - 1000
Magneto-aerotaxis in marine coccoid bacteria; Frankel RB et al.; Magnetotactic cocci swim persistently along local magnetic field lines in a preferred direction that corresponds to downward migration along geomagnetic field lines . Recently, high cell concentrations of magnetotactic cocci have been found in the water columns of chemically stratified, marine and brackish habitats, and not always in the sediments, as would be expected for persistent, downward-migrating bacteria . Here we report that cells of a pure culture of a marine magnetotactic coccus, designated strain MC-1, formed microaerophilic bands in capillary tubes and used aerotaxis to migrate to a preferred oxygen concentration in an oxygen gradient . Cells were able to swim in either direction along the local magnetic field and used magnetotaxis in conjunction with aerotaxis, i.e., magnetically assisted aerotaxis, or magneto-aerotaxis, to more efficiently migrate to and maintain position at their preferred oxygen concentration . Cells of strain MC-1 had a novel, aerotactic sensory mechanism that appeared to function as a two-way switch, rather than the temporal sensory mechanism used by other bacteria, including Magnetospirillum megnetotacticum, in aerotaxis . The cells also exhibited a response to short-wavelength light (< or = 500 nm), which caused them to swim persistently parallel to the magnetic field during illumination.

J Mol Evol, 1997 Aug, 45(2), 131 - 6
Horizontal transfer of genes coding for the photosynthetic reaction centers of purple bacteria; Nagashima KV et al.; Phylogenetic trees were drawn and analyzed based on the nucleotide sequences of the 1.5-kb gene fragment coding for the L and M subunits of the photochemical reaction center of various purple photosynthetic bacteria . These trees are mostly consistent with phylogenetic trees based on 16S rRNA and soluble cytochrome c, but differ in some significant details . This inconsistency implies horizontal transfer of the genes that code for the photosynthetic apparatus in purple bacteria . Possibilities of similar transfers of photosynthesis genes during the evolution of photosynthesis are discussed especially for the establishment of oxygenic photosynthesis.

J Virol, 1997 Aug, 71(8), 5774 - 81
Human immunodeficiency virus type 1 (HIV-1) protein Vif inhibits the activity of HIV-1 protease in bacteria and in vitro; Kotler M et al.; Human immunodeficiency virus type 1 (HIV-1) Vif is required for productive infection of T lymphocytes and macrophages . Virions produced in the absence of Vif have abnormal core morphology and those produced in primary T cells carry immature core proteins and low levels of mature capsid (M . Simm, M . Shahabuddin, W . Chao, J . S . Allan, and D . J . Volsky, J . Virol . 69:4582-4586, 1995) . To investigate whether Vif influences the activity of HIV-1 protease (PR), the viral enzyme which is responsible for processing Gag and Gag-Pol precursor polyproteins into mature virion components, we transformed bacteria to inducibly express truncated Gag-Pol fusion proteins and Vif . We examined the cleavage of polyproteins consisting of matrix to PR (Gag-PR), capsid to PR (CA-PR), and p6Pol to PR (p6Pol-PR) and evaluated HIV-1 protein processing at specific sites by Western blotting using antibodies against matrix, capsid, and PR proteins . We found that Vif modulates HIV-1 PR activity in bacteria mainly by preventing the release of mature MA and CA from Gag-PR, CA from CA-PR, and p6Pol from p6Pol-PR, with other cleavages being less affected . Using subconstructs of Vif, we mapped this activity to the N-terminal half of the molecule, thus identifying a new functional domain of Vif . Kinetic study of p6Pol-PR autocatalysis in the presence or absence of Vif revealed that Vif and N'Vif reduce the rate of PR-mediated proteolysis of this substrate . In an assay of in vitro proteolysis of a synthetic peptide substrate by purified recombinant PR we found that recombinant Vif and the N-terminal half of the molecule specifically inhibit PR activity at a molar ratio of the N-terminal half of Vif to PR of about 1 . These results suggest a mechanism and site of action of Vif in HIV-1 replication and demonstrate novel regulation of a lentivirus PR by an autologous viral protein acting in trans.

FEMS Microbiol Lett, 1997 Jul 15, 152(2), 355 - 61
Oral bacteria inhibit Helicobacter pylori growth; Ishihara K et al.; Various oral bacterial species were found to inhibit the growth of Helicobacter pylori strains . The growth inhibitory activities of most of these oral bacteria were adversely affected by heating at 80 degrees C for 60 min or by protease treatment, indicating that these bacteria produce bacteriocin-like inhibitory proteins against H . pylori strains . The antagonistic effects of oral bacteria against H . pylori may restrain colonization by this organism in the oral cavity.

J Biochem (Tokyo), 1997 Jul, 122(1), 41 - 8
Structure and expression of the dnaKJ operon of Buchnera, an intracellular symbiotic bacteria of aphid; Sato S et al.; Buchnera sp., an intracellular symbiont of the pea aphid (Acyrthosiphon pisum Harris), is a close phylogenetical relative of Escherichia coli, and synthesizes a large amount of symbionin, a GroEL homolog . The other heat shock protein homologs, which are not expressed as much as symbionin, have not been studied yet . In this study, we cloned the dnaK and dnaJ genes of Buchnera, and revealed that its DnaK and DnaJ are structurally very similar to those of E . coli . Amino acid residues and motifs proposed so far to be essential for the function of the E . coli DnaK and DnaJ were completely conserved in the Buchnera counterparts . However, Buchnera dnaKJ operon could not fully complement mutations of either dnaK or dnaJ of E . coli . This is probably because of a difference in net charge of DnaK and DnaJ between Buchnera and E . coli, and a unique structure of Buchnera DnaJ that prevents heterologous components from operating in concert . Buchnera dnaK and dnaJ formed an operon whose transcription is governed by a promoter structurally homologous to heat shock promoters of E . coli, although the cellular amount of dnaKJ mRNA was not affected by heat shock . Two inverted repeats flanking both sides of E . coli dnaJ were also found in the gene of Buchnera at the corresponding positions, suggesting that expression ratio of DnaK to DnaJ is regulated in a similar manner in the two organisms.

J Med Microbiol, 1997 Jul, 46(7), 571 - 8
Selective translocation of coliform bacteria adhering to caecal epithelium of rats during catabolic stress; Katouli M et al.; Adult conventional rats were starved for 48 h with or without haemorrhage at 24 h, and translocation of caecal coliforms to mesenteric lymph nodes (MLNs) was measured . Translocation was detected in three of 11 rats without haemorrhage, in 6 of 11 starved and sham-operated rats and in 12 of 22 rats after haemorrhage . In contrast, only one of 13 non-instrumented and fed control rats showed translocation . Translocation was associated with more coliforms adhering to caecal epithelium in rats . Coliform isolates from caecum, caecal epithelium and MLNs were characterised and grouped into different biochemical phenotypes (BPTs) by a biochemical fingerprinting method . Of 291 BPTs detected in the caecum of all rats, 108 were also found on caecal epithelium; 36 BPTs were detected in MLNs, of which 17 were not detected either in the caecum or on the caecal epithelium of the corresponding rats . One isolate from each of these 36 BPTs was selected and compared to the others . Four common (C) BPTs (i.e., C1-C4) were identified among them . Strains of C1 formed the majority of isolates from the caecum (79%), caecal epithelium (71%) and MLNs (91%) . In contrast, C2-C4 had a significantly lower incidence both in the caecum and on the caecal epithelium, but not in the MLNs . These findings indicate that not all caecal coliforms adhere to the epithelium during catabolic stress and that for translocation to occur, other bacterial properties besides adhesion are needed . It is also concluded that coliforms with a low incidence in the caecum can translocate with the same efficiency as those with a high incidence.

Curr Microbiol, 1997 Jul, 35(1), 44 - 7
Competition between ruminal cellulolytic bacteria for adhesion to cellulose; Mosoni P et al.; Competition for adhesion to cellulose among the three main ruminal cellulolytic bacterial species was studied using differential radiolabeling (14C/3H) of cells . When added simultaneously to cellulose, Ruminococcus flavefaciens FD1 and Fibrobacter succinogenes S85 showed some competition; however, both species were surpassed competitively by Ruminococcus albus 20 . When R . flavefaciens FD1 and F . succinogenes S85 were already adherent, R . albus 20 adhesion occurred without inhibition but involved R . flavefaciens FD1 detachment.

Microbiologia, 1997 Jun, 13(2), 209 - 14
Growth of methylaminotrophic, acetotrophic and hydrogenotrophic methanogenic bacteria on artificial supports; Urrutia H et al.; The efficiency of organic matter degradation in attached biomass reactors depends on the suitable selection of artificial support for the retention of bacterial communities . We have studied the growth on glass and clay beads of methylaminotrophic, acetotrophic and hydrogenotrophic methanogenic bacterial communities isolated from anaerobic reactors . Bacterial counts were performed by the standard MPN technique . Experiments were performed in 50 ml vials for 12 days at 35 degrees C . Increase in the counts of methylaminotrophic and hydrogenotrophic methanogens occurred on both glass and clay beads . The latter support material also stimulated the growth rate of methylaminotrophic methanogens.

J Anim Sci, 1997 Jun, 75(6), 1621 - 32
Regulation of uterine immune function during the estrous cycle and in response to infectious bacteria in sheep; Ramadan AA et al.; Uterine infections are a major reproductive problem in livestock . We conducted two experiments to investigate factors that may modulate uterine responses to infectious bacteria . In Exp . 1, ewes received intrauterine inoculations of either saline or bacteria (75 x 10(7) cfu of Actinomyces pyogenes and 35 x 10(7) cfu of Escherichia coli) on either d 0 or 7 of the estrous cycle . Vena caval samples containing uteroovarian blood were collected twice daily from 12 h before until 6 d after inoculation . Only ewes inoculated with bacteria on d 7 developed infections . Basal (4.8 vs .4 pmol), lipopolysaccharide-stimulated (14.2 vs 6.1 pmol), and concanavalin A-stimulated (65.8 vs 21.6 pmol) blastogenesis (i.e., {3H}thymidine incorporation) of vena caval lymphocytes was greater (P < or = .002) for ewes inoculated with bacteria or saline on d 0 rather than on d 7 . The number (per 100 white blood cells) of lymphocytes was greater (41.3 vs 30.8, P < .001) and that of neutrophils was less (42.5 vs 51.6, P < .001) in ewes inoculated on d 0 rather than d 7 . Bacteria increased (P < .05) vena caval PGF(2 alpha) but not PGE2 concentrations . In Exp . 2, two protein fractions (molecular weights of > or = 100 kDa and approximately 12.7 kDa) from chromatography of uterine flushings collected on d 0 or 7, or 18 d after ovariectomy on d 0 or 7, modulated phytohemagglutinin-stimulated blastogenesis; the heavier fraction from d 0 had a stimulatory component, but the major effects of the fractions were inhibitory . The differences in immune function and regulation between d 0 and 7 probably explain how the uterus of follicular phase ewes was able to prevent the development of an infection.

J Trauma, 1997 Jun, 42(6), 1073 - 9
Influence of selective decontamination of the digestive tract on cell-mediated immune function and bacteria/endotoxin translocation in thermally injured rats; Yao YM et al.; OBJECTIVE: To determine the influence of pretreatment with selective decontamination of the digestive tract (SDD) on systemic immunosuppression, and the relationship between bacteria/endotoxin translocation and abnormalities of immune function in thermally injured rats . DESIGN, MATERIALS, AND METHODS: Animals were subjected to a 40% full-thickness scald injury, and divided into SDD-treated and control groups . The treatment group received SDD (polymyxin E, tobramycin, and 5-flucytosine) by gavage twice daily for 3 days before the experiment and continued for 5 days after thermal injury . The control group was given the same amount of water . The parameters reflecting cell-mediated immunity, including splenocyte proliferation in response to mitogens, interleukin 2 (IL-2) production, and lymphocyte subpopulation, were measured before injury and 1 and 5 days after burn, respectively . MEASUREMENTS AND MAIN RESULTS: Thermal injury resulted in marked reduction in splenocyte proliferative response to T-cell mitogens, IL-2 production, and T-helper/suppressor cells (CD4/CD8) ratio . Prophylactic treatment with SDD significantly decreased the incidences of bacterial translocation and endotoxemia, prevented suppressive mitogenic response and inadequate IL-2 production (p < 0.05-0.01) but did not affect the abnormal ratio of CD4 to CD8 T lymphocytes in blood (p > 0.05) . CONCLUSIONS: These results suggest that bacteria/endotoxin translocation from the gut appears to be involved in cell-mediated immune dysfunction as a consequence of thermal injury . Pretreatment with SDD might attenuate postburn immunosuppression by preventing translocation events.

Curr Opin Struct Biol, 1997 Jun, 7(3), 407 - 15
Modular multidomain phosphoryl transfer proteins of bacteria; Reizer J et al.; Recent phylogenetic and structural analyses of multidomain phosphoryl transfer proteins of bacteria have revealed that interdomain (but not intradomain) splicing and fusion, as well as domain duplication and deletion, have occurred frequently during evolution . These events have been found to be exceedingly rare in certain other protein families . Domain-shuffling events are illustrated by examples from the superfamilies of phosphoenolpyruvate-dependent sugar phosphotransferase systems, their transcriptional regulatory protein targets of phosphorylation, sensor autokinase/response regulator signal transduction systems, and permeases of the ATP-binding-cassette type.

Surg Clin North Am, 1997 Jun, 77(3), 637 - 50
Wound infection . A failure of wound healing caused by an imbalance of bacteria; Robson MC; Infection in a wound, like infection elsewhere in the body, is a manifestation of a disturbed host-bacteria equilibrium in favor of the bacteria . This not only elicits a systemic septic response but actually inhibits the multiple processes involved in the wound healing scheme . Each process involved in healing is affected when bacteria proliferate in a wound . Wound infection, whether in an intentional operative incision, an acute traumatic laceration, or a chronic pressure ulcer, results when bacteria indigenous to the patient or exogenous to the wound achieve dominance over the systemic and local factors of host resistance . To be able to prevent and manage wound infections requires an understanding of how each prophylactic or therapeutic maneuver works to maintain or re-establish the bacteria-host balance . Only when this equilibrium is in balance can the normal processes of wound healing proceed to give a satisfactory healing trajectory.

Gastroenterology, 1997 Jun, 112(6), 1971 - 8
Effects of intestinal stasis on intercellular adhesion molecule 1 expression in the rat: role of enteric bacteria; Komatsu S et al.; BACKGROUND & AIMS: The mechanisms underlying the inflammatory changes associated with intestinal stasis are poorly understood . The objective of this study was to assess whether endothelial expression of intercellular adhesion molecule 1 (ICAM-1) and leukocyte recruitment are altered after intestinal stasis . METHODS: ICAM-1 expression and granulocyte recruitment were quantified in different tissues of Sprague-Dawley rats using the double-radiolabeled monoclonal antibody technique and peroxidase activity, respectively . RESULTS: Both constitutive and endotoxin-induced ICAM-1 expression were significantly higher in the cecum than in distal colon, a finding that cannot be explained by a difference in endothelial surface area between the two organs . Surgical procedures to improve cecal stool flow (cecostomy, ileocecostomy) elicited a significant decrease in constitutive ICAM-1 expression in both cecum and distal colon . Tissue peroxidase activity was normally higher in cecum than in distal colon, and this difference was significantly reduced by ileocecostomy . Oral administration of antibiotics (kanamycin and/or metronidazole for 2 days) significantly reduced constitutive ICAM-1 expression in the cecum, but not in the distal colon . CONCLUSIONS: This study indicates that intestinal stasis is associated with an increased expression of ICAM-1 and granulocyte infiltration, which may be mediated by enteric bacteria.

Curr Microbiol, 1997 Jun, 34(6), 340 - 7
The osmotic-1 locus of Neurospora crassa encodes a putative histidine kinase similar to osmosensors of bacteria and yeast; Schumacher MM et al.; Osmotically sensitive mutants of Neurospora crassa are unable to grow on medium supplemented with 4% NaCl, have altered morphologies and cell-wall compositions, and are resistant to dicarboximide fungicides . Osmotic-1 (os-1) mutants have a unique characteristic of forming protoplasts that grow and divide in specialized liquid medium, suggesting that the os-1+ gene product is important for cell-wall assembly . A cosmid containing the os-1+ locus of N . crassa, isolated from a genomic cosmid library by chromosomal walk from a closely linked gene, was used to subclone the os-1+ gene by functional complementation of an os-1 mutant . Analysis of the sequence of complementing DNA predicts that os-1+ encodes a predicted protein similar to sensor-histidine kinases of bacteria and a yeast osmosensor-histidine kinase . Importantly, the predicted os-1+ protein is identical to the N . crassa nik-1 predicted protein that was identified by using polymerase chain reaction primers directed against histidine kinase consensus DNA sequences . Our results indicate that nik-1 and os-1 encode the same osmosensing histidine kinase that plays an important role in the regulation of cell-wall assembly and, probably, other cell responses to changes in external osmolarity.

Antonie Van Leeuwenhoek, 1997 May, 71(4), 363 - 8
Molecular evolution in bacteria: surfaces, cathodes and anodes; Trevors JT; Molecular evolution is examined in bacteria with an emphasis on mineral surfaces, membranes, cathodes and anodes . In early molecular evolution, cathode-anode system may have been naturally occurring on a nm to micron scale . Secondly, the cathode-anode system could have been separated by a primitive, permeable lipid or microsphere on a mineral surface, that was a precursor of a more advanced membrane with a charge differential on either side of the membrane . These aspects will be considered from a theoretical evolutionary perspective.

Electrophoresis, 1997 May, 18(5), 834 - 9
Analysis of proteins from different phase variants of the entomopathogenic bacteria Photorhabdus luminescens by two-dimensional zymography; Ong KL et al.; Two-dimensional zymography which combines two-dimensional electrophoresis with zymography was used to analyze proteases and other proteins produced by different phase variants of two strains of Photorhabdus luminescens . Both the primary and secondary phases of P . luminescens strains Hp and Hm secreted proteases . The protease in P . luminescens Hp has a molecular weight (Mr) of 57,000 and an isoelectric point (pI) of 4.4 whereas that in P . luminescens Hm has an Mr of 59,000 and pI of 4.9 . Several putative protease degradation products were clearly visible in the zymograms from both bacterial strains . Two-dimensional zymography also showed that several secretory proteins were present only in particular phase variants and therefore could be used as specific markers . Unexpectedly, the two-dimensional zymography revealed that a nonsecretory protease with an Mr of 47,000 and a pI of 4.0 was present in the cell extracts of all phases of both P . luminescens Hp and Hm . The application of the two-dimensional zymography for the identification of other enzymes was also discussed.

Trends Microbiol, 1997 May, 5(5), 184 - 8
Intercellular communication and group behavior in bacteria; Gray KM; Group behavior in bacterial populations requires intercellular communication, generally by means of self-produced signals . As the model system of bacterial quorum sensing demonstrates, the integration of these 'group' signals with other global regulators can lead to very complex and sophisticated interactions that are not necessarily limited to the signal-producing species alone.

Appl Environ Microbiol, 1997 May, 63(5), 1847 - 51
Glucose transport by mixed ruminal bacteria from a cow; Kajikawa H et al.; The glucose transport of mixed ruminal bacteria harvested from a holstein cow fed 5.0 kg of Italian ryegrass and 1.5 kg of flaked corn a day was investigated . The Eadie-Hofstee plot characterized two transport systems: a high-affinity, low-velocity system and a low-affinity, high-velocity system . The former system (K(m) = 16 microM; Vmax = 2.2 nmol/min/mg of protein) is considered dominant under this feeding condition based on the glucose concentration in the rumen (< 1 mM) . In light of the facts that the protonophore SF6847 and the lipophilic triphenylmethyl phosphonium ion had no effect on the high-affinity system and an artificially generated proton gradient and electrical potential across the cell membrane did not increase glucose transport, a proton motive force is not be involved in the system . On the other hand, from the facts that chlorhexidine inhibited about 90% of the high-affinity system while iodoacetate showed no significant effect, and a high phosphoenolpyruvate-dependent phosphorylation of glucose was actually shown, the phosphoenolpyruvate-dependent phosphotransferase system is considered the main system in the high-affinity system . Moreover, as shown by the facts that harmaline inhibited about 30% of the high-affinity system and the artificially generated sodium gradient across the cell membrane significantly stimulated glucose transport, this system also includes sodium symport to some degree . The high-affinity system was sensitive to a decrease in pH (< 6.5) and was inhibited by the presence of sucrose, mannose, and fructose.

Appl Environ Microbiol, 1997 May, 63(5), 1721 - 4
Subcuticular bacteria from the brittle star Ophiactis balli (Echinodermata: Ophiuroidea) represent a new lineage of extracellular marine symbionts in the alpha subdivision of the class Proteobacteria; Burnett WJ et al.; Many species of echinoderms, in all five extant classes, contain subcuticular bacterial symbionts (SCB) . The role of these extracellular symbionts and the nature of the relationship remain unclear . We have sequenced 16S rRNA genes from symbionts to determine their phylogenetic affinities . Symbionts of an ophiuroid, Ophiactis balli, appear closely related to bacteria within the alpha group of the class Proteobacteria, including intracellular endosymbionts and pathogens . SCB are clearly of separate origin from other documented major groups of marine symbiotic bacteria.

J Biomed Mater Res, 1997 May, 35(2), 217 - 32
Tissue reactions to bacteria-inoculated rat lead samples . I . Effect of local gentamicin release through vicinal sponge or solution-dipping; van Wachem PB et al.; The effect of local gentamicin release through a vicinal collagen sponge or through preoperative solution-dipping of rat lead samples was investigated in an early-infection model . The efficacy of these methods and their effect on tissue response were determined . It was demonstrated that both methods of local gentamicin release suppress lead-related infectious complications as compared to the control lead, which showed a high presence of inflamed/infected tissues and bacterial growth at each explantation time point . The first day the vicinal collagen sponge was more effective in suppressing the infection than was the solution-dipped lead, probably because there is a faster and higher dose release of gentamicin from the sponge . However, continued implantation time revealed that gentamicin release from the solution-dipped lead was more effective than the sponge . This supports our hypothesis that the presence of lumina are decisive for bacterial growth and persistence of implant-related infections.

Biochem J, 1997 Apr 15, 323 ( Pt 2), 393 - 9
Structure of a truncated human surfactant protein D is less effective in agglutinating bacteria than the native structure and fails to inhibit haemagglutination by influenza A virus; Eda S et al.; Surfactant protein D (SP-D) is a lung-specific protein that is synthesized and secreted by lung epithelial cells and is believed to play an important role in lung host defence . This protein belongs to the C-type lectin family, which is characterized by an N-terminal cysteine-rich domain, a collagen-like domain, a neck domain and a carbohydrate recognition domain (CRD) . To elucidate the biological actions of this animal lectin against such pathogens as micro-organisms, the biological activities of a recombinant partial SP-D lacking a collagen-like domain were examined . A recombinant human SP-D, consisting of a short collagen region (two repeats of Gly-Xaa-Yaa amino acid sequences), the neck domain and the CRD, was expressed in Escherichia coli . The recombinant SP-D was purified on a nickel column and then on a maltose-agarose column . This protein can form a trimeric structure owing to the neck domain and exhibits sugar-binding activity and specificity similar to those of native human SP-D . The recombinant SP-D caused dose-dependent and calcium-dependent agglutination of E . coli Y1088 . The agglutination titre (the concentration required to achieve a 50% decrease in light transmission by agglutination) of recombinant SP-D was approx . 6-fold that of native SP-D . As for conglutination, the recombinant trimeric conglutinin required 8-16-fold higher concentrations than the native counterpart . In haemagglutination inhibition (HI) of influenza A virus, although native and recombinant conglutinin showed similar levels of HI activity, the recombinant SP-D was unable to inhibit haemagglutination, even at a concentration approx . 120-fold that of the native SP-D . The lectin precipitation and lectin blot assays showed that the truncated SP-D could bind to influenza A virus as well as native SP-D did . These results indicate that the agglutination activity of trimeric collectins can be largely retained, and furthermore that the oligomeric structure with several hands at opposite sites can enhance agglutination activity . The difference in HI activity against influenza A virus between native and recombinant SP-D suggests that SP-D uses a different mechanism from that of conglutinin to inhibit viral haemagglutination.

Biochemistry, 1997 Apr 15, 36(15), 4489 - 96
pH-metric study of reaction centers from photosynthetic bacteria in micellular solutions: protonatable groups equilibrate with the aqueous bulk phase; Kalman L et al.; Hydrogen ion equilibria of the reaction center protein from photosynthetic purple bacteria Rhodobacter sphaeroides and Rhodobacter capsulatus dissolved in micellular solution were studied by acid-base titration to estimate the water accessibility of protonatable residues of the protein determined from structural data . The ionizable amino acids of the reaction center underwent protonation-deprotonation with protons from the interfacial layer, which, however, exchanged protons from the aqueous bulk phase . The equilibrium was described in terms of the buffering capacity of the multiphase system . The detergents decreased the proton activity coefficient (increased the buffering capacity) of the aqueous solution by a factor of 0.33 (in 0.03% Triton X-100 and LDAO) and 0.12 (0.04% dodecyl beta-D-maltoside) . The observed buffering capacities of the reaction center protein were large and detergent-dependent . However, corrections for proton activities made the pH dependence of buffering capacities in different detergents uniform and similar to that expected from the number and pK values of protonatable groups of the protein . The vast majority of protonatable amino acids of the reaction center are in protonation equilibria with the aqueous bulk phase on an extended time scale.

Biochemistry (Mosc), 1997 Apr, 62(4), 386 - 90
A secretory protein involved in the antagonistic interactions between methanotrophic bacteria; Pashkova NI et al.; Antagonistic interactions in mixed culture of methanotrophic bacteria Methylomonas methanica 12 and Methylocystis minimus 33 were investigated . The inhibitory action of Mcs . minimus exometabolites against Mm . methanica grown in liquid medium was found to be specific . Ultrafiltration established that the molecular weight of the substance having inhibitory activity lies within the range 2-10 kD . The activity is protease sensitive and relatively stable to heating . Electrophoretic analysis showed that a protein with molecular weight of approximately 8 kD prevailed in Mcs . minimus culture liquid . When Mm . methanica cells were incubated in culture liquid of Mcs . minimus, the sorption of the 8 kD protein by target cells was observed . This suggests that the inhibitory effect may be associated with the 8 kD protein which has properties similar to known bacteriocins.

Vet Med (Praha), 1997 Apr, 42(4), 111 - 23
{Use of molecular genetics for identification and differentiation of various strains and species of bacteria}; Rychlik I et al.; The aim of the paper is to inform on methods and practical application of DNA fingerprinting in typing of living organisms . Methods discussed in the review include standard DNA fingerprinting, plasmid profile analysis, RAPD PCR and direct sequencing of selected parts of genomes . In each method molecular basis together with its advantages and limitations is explained . All described methods are supplemented with selected cases of their practical application.

J Appl Microbiol, 1997 Apr, 82(4), 455 - 61
Analysis of cytotoxicity and invasiveness of heterotrophic plate count bacteria (HPC) isolated from drinking water on blood media; Edberg SC et al.; Heterotrophic plate count (HPC) bacteria are naturally present in all aqueous environments . These bacteria undergo multiplication cycles in drinking water, especially in closed containers (bottled water) or in tap water when chlorine levels are dissipated, such as in dead ends in water mains or household plumbing . A study was undertaken to estimate health risk from these naturally occurring bacteria by the determination of cytotoxicity and invasiveness in a human enterocyte cell line . HPC bacteria were isolated from bottled and tap water samples by enumerating them under physical and chemical conditions analogous to human physiology . All HPC bacteria were examined at both log and lag phase of their growth cycles . Bacterial broth supernatant fluids were also tested to serve as critical negative controls . Naturally occurring HPC bacteria demonstrated low invasiveness and cytotoxicity with more than 95% of isolates showing equivalency to broth supernatant fluid . When showing either invasiveness or cytotoxicity, only a small number of cells from the culture were positive . Of those that were positive, log phase HPC bacteria were significantly more cytotoxic and invasive than those from stationary phase . Bacterial broth controls demonstrated varied, but often marked, cytotoxicity.

Appl Environ Microbiol, 1997 Apr, 63(4), 1564 - 9
Influence of water chlorination on the counting of bacteria with DAPI (4',6-diamidino-2-phenylindole); Saby S et al.; Counting bacteria in drinking water samples by the epifluorescence technique after 4',6-diamidino-2-phenylindole (DAPI) staining is complicated by the fact that bacterial fluorescence varies with exposure of the cells to sodium hypochlorite . An Escherichia coli laboratory-grown suspension treated with sodium hypochlorite (5 to 15 mg of chlorine liter-1) for 90 min was highly fluorescent after DAPI staining probably due to cell membrane permeation and better and DAPI diffusion . At chlorine concentrations greater than 25 mg liter-1, DAPI-stained bacteria had only a low fluorescence . Stronger chlorine doses altered the DNA structure, preventing the DAPI from complexing with the DNA . When calf thymus DNA was exposed to sodium hypochlorite (from 15 to 50 mg of chlorine liter-1 for 90 min), the DNA lost the ability to complex with DAPI . Exposure to monochloramine did not have a similar effect . Treatment of drinking water with sodium hypochlorite (about 0.5 mg of chlorine liter-1) caused a significant increase in the percentage of poorly fluorescent bacteria, from 5% in unchlorinated waters (40 samples), to 35 to 39% in chlorinated waters (40 samples) . The presence of the poorly fluorescent bacteria could explain the underestimation of the real number of bacteria after DAPI staining . Microscopic counting of both poorly and highly fluorescent bacteria is essential under these conditions to obtain the total number of bacteria . A similar effect of chlorination on acridine orange-stained bacteria was observed in treated drinking waters . The presence of the poorly fluorescent bacteria after DAPI staining could be interpreted as a sign of dead cells.

Proc Natl Acad Sci U S A, 1997 Apr 1, 94(7), 3274 - 8
Prevention of insect-borne disease: an approach using transgenic symbiotic bacteria; Durvasula RV et al.; Expression of molecules with antiparasitic activity by genetically transformed symbiotic bacteria of disease-transmitting insects may serve as a powerful approach to control certain arthropod-borne diseases . The endosymbiont of the Chagas disease vector, Rhodnius prolixus, has been transformed to express cecropin A, a peptide lethal to the parasite, Trypanosoma cruzi . In insects carrying the transformed bacteria, cecropin A expression results in elimination or reduction in number of T . cruzi . A method has been devised to spread the transgenic bacteria to populations of R . prolixus, in a manner that mimics their natural coprophagous route of symbiont acquisition.

J Biol Chem, 1997 Mar 7, 272(10), 6805 - 11
Phosphorylation of protein kinase Cdelta (PKCdelta) at threonine 505 is not a prerequisite for enzymatic activity . Expression of rat PKCdelta and an alanine 505 mutant in bacteria in a functional form; Stempka L et al.; A structural feature shared by many protein kinases is the requirement for phosphorylation of threonine or tyrosine in the so-called activation loop for full enzyme activity . Previous studies by several groups have indicated that the isotypes alpha, betaI, and betaII of protein kinase C (PKC) are synthesized as inactive precursors and require phosphorylation by a putative "PKC kinase" for permissive activation . Expression of PKCalpha in bacteria resulted in a nonfunctional enzyme, apparently due to lack of this kinase . The phosphorylation sites for the PKC kinase in the activation loop of PKCalpha and PKCbetaII could be identified as Thr497 and Thr500, respectively . We report here that PKCdelta, contrary to PKCalpha, can be expressed in bacteria in a functional form . The activity of the recombinant enzyme regarding substrate phosphorylation, autophosphorylation, and dependence on activation by 12-O-tetradecanoylphorbol-13-acetate as well as the Km values for two substrates are comparable to those of recombinant PKCdelta expressed in baculovirus-infected insect cells . By site-directed mutagenesis we were able to show that Thr505, corresponding to Thr497 and Thr500 of PKCalpha and PKCbetaII, respectively, is not essential for obtaining a catalytically competent conformation of PKCdelta . The mutant Ala505 can be activated and does not differ from the wild type regarding activity and several other features . Ser504 can not take over the role of Thr505 and is not prerequisite for the kinase to become activated, as proven by the unaffected enzyme activity of respective mutants (Ala504 and Ala504/Ala505) . These results indicate that phosphorylation of Thr505 is not required for the formation of functional PKCdelta and that at least this PKC isoenzyme differs from the isotypes alpha, betaI, and betaII regarding the permissive activation by a PKC kinase.

Lett Appl Microbiol, 1997 Mar, 24(3), 207 - 10
Use of oxygen-permeable silicone rubber pouches for growing mass cultures of bacteria; Giambernardi TA et al.; Growth of most bacteria often involves the use of expensive incubated shaker systems . In this report, oxygen-permeable silicone rubber pouches, with oxygen permeability over 100 times higher than other polymers, were employed for growing bacterial cultures . With little, if any, agitation oxygen-permeable silicone rubber pouches produced bacterial growth rates equivalent to growth rates obtained in shaker flasks . The silicone rubber pouch described has a glass cuvette integrated into its design that permits readings of bacterial density without opening the pouch . One can sterilize and store powdered bacterial culture medium in silicone rubber pouches; therefore, bacterial cultures can be initiated by simply adding water and bacteria.

J Bacteriol, 1997 Mar, 179(6), 2047 - 52
Transposition without transposase: a spontaneous mutation in bacteria; Rappleye CA et al.; Transposition mutations are typically associated with the activities of transposable elements such as transposons and insertion sequences, whose mobility is dependent upon transposase enzymes that catalyze exchanges between element ends and target sites . We describe a single transposition event in which a block of donor sequence is inserted at a target site without the involvement of any known transposase or the ends of any known transposable element . We propose that this is a new type of spontaneous mutation which may be difficult to detect in standard mutant hunts but may be of evolutionary importance.

Tidsskr Nor Laegeforen, 1997 Feb 28, 117(6), 838 - 41
{Floor cleaning methods of patients' room . Effect on bacteria, dirt and particles}; Andersen BM et al.; The effect of floor cleaning on bacteria, organic materials and particles in the patients' rooms was studied at Ulleval University Hospital, Oslo, Norway . Four cleaning methods were compared; dust-adhesive (dry), humified, wet mopping, and regular wet washing (RWW) without a mop . The following tests were taken from the floor before and after cleaning: bacterial counts (colony forming units = CFU) and ATP (presence of organic materials), and from the air: CFU/m3 air, and particle counts/m3 air . Humified mopping and dry mopping reduced the bacterial counts from the floor by 75% and 55% respectively (p = 0.005 and p = 0.014, using contact medium) . The wet mopping had no statistically significant effect, while the wet washing even increased the CFU on the floor by 35-50% (p = 0.017 with contact medium, and p = 0.028 with petrifilm) . The two wet methods were the most effective, however, in removing organic materials from the floor; 65% to 70% reduction (p = 0.051 and p =0.008) . The CFU/m3 air was low both before (50-130 CFU/m3) and after (70-110 CFU/m3) cleaning . A slight increase in airborne particles was measured after dry mopping . Combined use of humified mopping and wet mopping is recommended, but is dependent on a well prepared and finished floor surface.

Nucleic Acids Res, 1997 Feb 15, 25(4), 701 - 12
Comparative analysis of the genomes of the bacteria Mycoplasma pneumoniae and Mycoplasma genitalium; Himmelreich R et al.; The sequenced genomes of the two closely related bacteria Mycoplasma genitalium and Mycoplasma pneumoniae were compared with emphasis on genome organization and coding capacity . All the 470 proposed open reading frames (ORFs) of the smaller M.genitalium genome (580 kb) were contained in the larger genome (816 kb) of M.pneumoniae . There were some discrepancies in annotation, but inspection of the DNA sequences showed that the corresponding DNA was always present in M . pneumoniae . The two genomes could be subdivided into six segments . The order of orthologous genes was well conserved within individual segments but the order of these segments in both bacteria was different . We explain the different organization of the segments by translocation via homologous recombination . The translocations did not disturb the continuous bidirectional course of transcription in both genomes, starting at the proposed origin of replication . The additional 236 kb in M.pneumoniae,compared with theM.genitalium genome, were coding for 209 proposed ORFs not identified in M.genitalium . Of these ORFs, 110 were specific to M.pneumoniae exhibiting no significant similarity to M.genitalium ORFs, while 76 ORFs were amplifications of ORFs existing mainly as single copies in M . genitalium . In addition, 23 ORFs containing a copy of either one of the three repetitive DNA sequences RepMP2/3, RepMP4 and RepMP5 were annotated in M.pneumoniae but not in M.genitalium,although similar DNA sequences were present . TheM.pneumoniae-specific genes included a restriction-modification system, two transport systems for carbohydrates, the complete set of three genes coding for the arginine dihydrolase pathway and 14 copies of the repetitive DNA sequence RepMP1 which were part of several different translated genes with unknown function.

Ugeskr Laeger, 1997 Feb 10, 159(7), 952 - 5
{Influence of local air suction on the density of air-borne bacteria during cementation of alloplasties}; Enggaard TP et al.; At joint replacement operations local air suction is used to reduce the air pollution from organic solvents in the operation theatre during insertion of cement and prosthesis . In order to find out whether the local suction in an ultraclean-air operation theatre with laminar airflow influenced the number of colony forming units (cfu) of bacterial in vicinity of the wound, one m3 of air was sampled 20 cm and one metre from the wound before, during and after use of local suction during insertion of cement and prosthesis using a Sartorius membrane filter sampler . There was no significant difference between the groups in the numbers of cfu of bacteria found . It is concluded that use of local air suction over the operative area while cementing hip prosthesis does not affect the number of bacteria in the vicinity of the operation.

Zygote, 1997 Feb, 5(1), 21 - 30
Virus-like particles, bacteria and microsporidia affect spindle-associated membranes in spermatocytes of Lepidoptera species; Wolf KW; Larval testes of four Lepidoptera species were examined using electron microscopy . The testes of one species, the Mediterranean mealmoth Ephestia kuehniella (Pyralidae), were devoid of intracellular pathogens and serve as a control . In this species, metaphase spindles of primary spermatocytes showed a thick layer of perispindle membranes . The membranes were structurally very similar to the agranular endoplasmic reticulum . Membranes of this type occurred also at high frequency throughout the spindle matrix . The analysis of larval testes of Pieris brassicae (Pieridae) revealed virus-like particles within spermatocytes . In another species, Philudoria potatoria (Lasiocampidae), the spermatocytes possessed intracellular bacteria . Whereas the pathogens were found within the germ cells in these species, a fourth species, Plutella xylostella (Plutellide), showed microsporidia within somatic cells of the testis sheath . In all the infected animals, the mass of perispindle membranes was reduced in comparison with spermatocytes of E . kuehniella . However, spindle structure appeared regular in the infected animals . This indicates that a thick layer of perispindle membranes is not decisive for spindle assembly and function in male meiosis of Lepidopera.

Antonie Van Leeuwenhoek, 1997 Feb, 71(1-2), 59 - 67
Enzymology of the oxidation of ammonia to nitrite by bacteria; Hooper AB et al.; The enzymes which catalyze the oxidation of ammonia to nitrite by autotrophic bacteria are reviewed . A comparison is made with enzymes which catalyze the same reactions in methylotrophs and organotrophic heterotrophic bacteria.

Protein Sci, 1997 Feb, 6(2), 464 - 8
Evidence for PDZ domains in bacteria, yeast, and plants; Ponting CP; Several dozen signaling proteins are now known to contain 80-100 residue repeats, called PDZ (or DHR or GLGF) domains, several of which interact with the C-terminal tetrapeptide motifs X-Ser/Thr-X-Val-COO- of ion channels and/or receptors . PDZ domains have previously been noted only in mammals, flies, and worms, suggesting that the primordial PDZ domain arose relatively late in eukaryotic evolution . Here, techniques of sequence analysis-including local alignment, profile, and motif database searches-indicate that PDZ domain homologues are present in yeast, plants, and bacteria . It is suggested that two PDZ domains occur in bacterial high-temperature requirement A (htrA) and one in tail-specific protease (tsp) homologues, and that a yeast htrA homologue contains four PDZ domains . Sequence comparisons suggest that the spread of PDZ domains in these diverse organisms may have occurred via horizontal gene transfer . The known affinity of Escherichia coli tsp for C-terminal polypeptides is proposed to be mediated by its PDZ-like domain, in a similar manner to the binding of C-terminal polypeptides by animal PDZ domains.

Appl Environ Microbiol, 1997 Feb, 63(2), 743 - 8
Competition for cellobiose among three predominant ruminal cellulolytic bacteria under substrate-excess and substrate-limited conditions; Shi Y et al.; The ruminal cellulolytic bacteria Ruminococcus flavefaciens FD-1 and Fibrobacter succinogenes S85 coexisted in substrate-excess coculture with about equal population size, but R . flavefaciens outcompeted F . succinogenes for cellobiose in the substrate-limited cocultures whether the two strains were coinoculated or a steady-state culture of F . succinogenes was challenged by R . flavefaciens . This outcome of competition between these two strains is due to a classical pure and simple competition mechanism based on affinity for cellobiose . Although the population size of F . succinogenes was much higher (> 70%) than that of another cellulolytic species, Ruminococcus albus 7 in substrate-excess coculture, F . succinogenes was replaced by a population of R . albus in the substrate-limited coculture in both coinoculation and challenge experiments . R albus outcompeted F . succinogenes, apparently due to selection in the chemostat of a population of R . albus with a higher affinity for cellobiose . R . albus also outcompeted R . flavefaciens under substrate-limited conditions.

Appl Environ Microbiol, 1997 Feb, 63(2), 734 - 42
Competition for cellulose among three predominant ruminal cellulolytic bacteria under substrate-excess and substrate-limited conditions; Shi Y et al.; Three predominant ruminal cellulolytic bacteria (Fibrobacter succinogenes S85, Ruminococcus flavefaciens FD-1, and Ruminococcus albus 7) were grown in different binary combinations to determine the outcome of competition in either cellulose-excess batch culture or in cellulose-limited continuous culture . Relative populations of each species were estimated by using signature membrane-associated fatty acids and/or 16S rRNA-targeted oligonucleotide probes . Both F . succinogenes and R . flavefaciens coexisted in cellulose-excess batch culture with similar population sizes (58 and 42%, respectively; standard error, 12%) . By contrast, under cellulose limitation R . flavefaciens predominated (> 96% of total cell mass) in coculture with F . succinogenes, regardless of whether the two strains were inoculated simultaneously or whether R . flavefaciens was inoculated into an established culture of F . succinogenes . The predominance of R . flavefaciens over F . succinogenes under cellulose limitation is in accord with the former's more rapid adherence to cellulose and its higher affinity for cellodextrin products of cellulose hydrolysis . In batch cocultures of F . succinogenes and R . albus, the populations of the two species were similar . However, under cellulose limitation, F . succinogenes was the predominant strain (approximately 80% of cell mass) in cultures simultaneously coinoculated with R . albus . The results from batch cocultures of R . flavefaciens and R . albus were not consistent within or among trials: some experiments yielded monocultures of R . albus (suggesting production of an inhibitory agent by R . albus), while others contained substantial populations of both species . Under cellulose limitation, R . flavefaciens predominated over R . albus (85 and 15%, respectively), as would be expected by the former's greater adherence to cellulose . The retention of R . albus in the cellulose-limited coculture may result from a combination of its ability to utilize glucose (which is not utilizable by R . flavefaciens), its demonstrated ability to adapt under selective pressure in the chemostat to utilization of lower concentrations of cellobiose, a major product of cellulose hydrolysis, and its possible production of an inhibitory agent.

Appl Environ Microbiol, 1997 Feb, 63(2), 644 - 51
Development and application of 16S rRNA-targeted probes for detection of iron- and manganese-oxidizing sheathed bacteria in environmental samples; Siering PL et al.; Comparative sequence analysis of the 16S rRNA genes from several Leptothrix and Sphaerotilus strains led to the design of an oligonucleotide probe (PS-1) based on a sequence within the hypervariable region 1 specific for four Leptothrix strains and for one of the four Sphaerotilus natans strains examined . Another probe (PSP-6) was based on a sequence within the hypervariable region 2 . PSP-6 was specific for one of the two evolutionary lineages previously described for Leptothrix spp . (P . L . Siering and W . C . Ghiorse, Int . J . Syst . Bacteriol . 46:173-182, 1996) . Fluorescein-labeled oligonucleotide probes were synthesized, and their specificity for fluorescence in situ hybridization identification was confirmed by a laser scanning microscopy technique (W . C . Ghiorse, D . N . Miller, R . L . Sandoli, and P . L . Siering, Microsc . Res . Tech . 33:73-86, 1996) to compare whole-cell hybridizations of closely related bacteria . Probe specificity was also tested in dot blot against total RNA isolated from four Leptothrix strains, four Sphaerotilus strains, and 15 other members of the class Proteobacteria . When the probes were tested on samples from the Sapsucker Woods wetland habitat where Leptothrix spp . are thought to play a role in manganese and iron oxidation, positive signals were obtained from several sheathed filamentous bacteria including some that were morphologically similar to previously isolated strains of "Leptothrix discophora." Other unknown filamentous sheathed bacteria also gave strong positive signals . This work provides a foundation for future studies correlating the presence of members of the Leptothrix-Sphaerotilus group of sheathed bacteria with manganese and iron oxidation activity in habitats where biological iron and manganese oxidation are important environmental processes.

Nucleic Acids Res, 1997 Feb 1, 25(3), 675 - 6
An effective method of RNA extraction from bacteria refractory to disruption, including mycobacteria; Mangan JA et al.; A high yield, rapid and simple procedure is described for extracting RNA from mycobacteria and other micro-organisms refractory to disruption . The method yielded 20 microg RNA/109 Mycobacterium bovis BCG, more than 10 times greater than our previous method . Intact full length hsp 70 (dnaK) mRNA was detected by northern blotting and quantitated after heat shock by slot blot hybridisation.

J Bacteriol, 1997 Feb, 179(3), 576 - 82
Barriers to heterologous expression of a selenoprotein gene in bacteria; Tormay P et al.; The specificity parameters counteracting the heterologous expression in Escherichia coli of the Desulfomicrobium baculatum gene (hydV) coding for the large subunit of the periplasmic hydrogenase which is a selenoprotein have been studied . hydV'-'lacZ fusions were constructed, and it was shown that they do not direct the incorporation of selenocysteine in E . coli . Rather, the UGA codon is efficiently suppressed by some other aminoacyl-tRNA in an E . coli strain possessing a ribosomal ambiguity mutation . The suppression is decreased by the strA1 allele, indicating that the hydV selenocysteine UGA codon has the properties of a "normal" and suppressible nonsense codon . The SelB protein from D . baculatum was purified; in gel shift experiments, D . baculatum SelB displayed a lower affinity for the E . coli fdhF selenoprotein mRNA than E . coli SelB did and vice versa . Coexpression of the hydV'-'lacZ fusion and of the selB and tRNA(Sec) genes from D . baculatum, however, did not lead to selenocysteine insertion into the protein, although the formation of the quaternary complex between SelB, selenocysteyl-tRNA(Sec), and the hydV mRNA recognition sequence took place . The results demonstrate (i) that the selenocysteine-specific UGA codon is readily suppressed under conditions where the homologous SelB protein is absent and (ii) that apart from the specificity of the SelB-mRNA interaction, a structural compatibility of the quaternary complex with the ribosome is required.

Curr Microbiol, 1997 Feb, 34(2), 103 - 9
Isolation and Characterization of Dehalogenases from2,2-Dichloropropionate-Degrading Soil Bacteria
Schwarze R, Brokamp A, Schmidt FRJ.
Five bacterial strains were isolated from polluted soilscapable of degrading 2,2-dichloropropionate . In crude extracts, dehalogenaseactivity against haloacetates and longer-chained 2-haloalkanoic acids couldbe detected . Results from activity staining indicated that all bacterialstrains expressed a single dehalogenase . In further biochemicalcharacterization, two types of D,L-specific 2-haloalkanoic acid dehalogenaseswere described, which are different from each other not only in molecularweight and electrophoretic mobility, but also in sensitivity towards thiolreagents . Dehalogenases of these strains have been shown to be inducible andare catalyzing halide hydrolysis with inversion of product configuration.

J Biol Chem, 1997 Jan 17, 272(3), 1670 - 6
Pleiotropic effects of puf interposon mutagenesis on carotenoid biosynthesis in Rubrivivax gelatinosus . A new gene organization in purple bacteria; Ouchane S et al.; Rubrivivax gelatinosus mutants affected in the carotenoid biosynthesis pathways were created by interposon mutagenesis within the puf operon . Genetic and biochemical analysis of several constructed mutants suggest that at least crtC is localized downstream of the puf operon and that it is cotranscribed with this operon . Sequence analysis confirmed the genetic data and showed the presence of crtD and crtC genes downstream of the puf operon, a localization different from that known for other purple bacteria . Inactivation of the crtD gene indicated that the two crt genes are cotranscribed and that they are involved not only in the hydroxyspheroidene biosynthesis pathway as in Rhodobacter sphaeroides and R . capsulatus, but also in the spirilloxanthin biosynthesis pathway . Carotenoid genes implicated in the spirilloxanthin biosynthesis pathway were thus identified for the first time . Furthermore, analysis of carotenoid synthesis in the mutants gave genetic evidence that crtD and crtC genes are cotranscribed with the puf operon using the oxygen-regulated puf promoter.

J Basic Microbiol, 1997, 37(3), 205 - 11
Degradation of dimeric lignin model compounds by aerobic bacteria isolated from the hindgut of xylophagous termites; Kuhnigk T et al.; The capability of the intestinal flora from the gut of xylophagous termites of degrading lignin model compounds was investigated . Different dimeric lignin model compounds-degrading bacteria were obtained from the hindgut flora of Mastotermes darwiniensis Froggatt, Reticulitermes santonensis Feytaud, Nasutitermes nigriceps Haldeman and Zootermopsis angusticollis Hagen . In the presence of oxygen dimeric model compounds were degraded by all isolates . This indicates that the hindgut flora of termites is basically able to produce substrate for their host from aromatic extractives of wood.

Membr Cell Biol, 1997, 11(1), 1 - 16
Effect of hydration on the structure, dynamics and function of photosynthetic membranes of purple bacteria; Aksyonov SI et al.; NMR spectra and relaxation times T1 and T2 for 31P in membranes of Rhodobacter sphaeroides were investigated at different relative humidity levels . The results are compared to the hydration curves, fatty acid composition and the structure-dynamic and functional characteristics of the membranes of photosynthetic bacteria Rb . sphaeroides, Rhodospirillum rubrum and Ectothiorhodospira shaposhnikovii . The differences in the state of lipid phase of these membranes are revealed under low humidity, and this is conducive to variability of their structural dynamic and functional characteristics during the hydration process . Based on the results obtained and the data on model systems, four stages of hydration process are distinguished with different effects on the structure and dynamics of membrane components . These stages are: hydration of a portion of polar groups, involvement of water molecules in the hydrogen bonds within macromolecules and the lipid phase, hydration of all polar groups with the appearance of water with high dielectric constant thus making possible the lateral diffusion within the membrane and realization, through water participation, of conditions within organelles and cells required for the process regulation at these levels . The mechanism of water action on various membrane components and their dynamics at each stage are discussed, as well as the effect of different types of motion on the efficiency and regulation of electron transport in the photosynthetic chain of the membranes studied.

Folia Microbiol (Praha), 1997, 42(3), 165 - 70
Diversity and specificity of protein-phosphorylating systems in bacteria; Cozzone AJ; Bacteria harbor three different protein-phosphorylating systems which regulate distinct physiological processes: first, the nucleotide-dependent system which modifies hydroxyl groups of amino acids in protein substrates; second, the two-component system which involves both sensor kinase and response regulator; third, the phosphoenolpyruvate-dependent phosphotransferase system . These systems share a number of structural and functional similarities with the protein-phosphorylating systems of eukaryotes.

Biosystems, 1997, 43(2), 83 - 95
A quantum-theoretical approach to the phenomenon of directed mutations in bacteria (hypothesis); Ogryzko VV; The Darwinian paradigm of biological evolution is based on the independence of genetic variations from selection which occurs afterwards . However, according to the phenomenon of directed mutations, some genetic variations occur mostly when the conditions favorable for their growth are created . I propose that the explanation of this phenomenon should not rely on any special 'mechanism' for the appearance of directed mutations, but rather should be based on the principles of quantum theory . I consider a physical model of adaptation whereby a polarized photon, passing through a polarizer, changes its polarization according to the angle of the polarizer . This adaptation occurs by selection of the 'fitted' polarized state which exists as a component of superposition in the initial state of the photon . However, since the same state of the incoming photon should be decomposed differently depending on the angle of the polarizer, in this case the set of variations subjected to selection depends upon the selective conditions themselves . This reveals the crucial difference between this model of adaptation and canonical Darwinian selection . Based on this analogy, the capacity of a cell to grow in particular conditions is considered an observable of the cell; the plating experiments are interpreted as measurement of this observable . The only nontrivial suggestion of the paper states that the cell, analogously to the polarized photon, may be in a state of superposition of eigenfunctions of the operator which represents this observable, and with some probability can appear as a mutant upon the measurement . Alternative growth conditions correspond to the decomposition of the same state vector into a different superposition, consistent with measurement of a different observable and appearance of different mutants . Thus, consistent with the suggested analogy, directed mutations are explained as a result of random choice from the set of outcomes determined by the environment.

Mikrobiologiia, 1997 Jan-Feb, 66(1), 5 - 13
{Cell differentiation and its regulation during genetic transformation in bacteria}; Prozorov AA; Mechanisms determining cell differentiation at the intracellular and intercellular levels during genetic transformation of certain bacterial species are reviewed . The "predetermination" both of cell outer layers and of chromosomal DNA to transformation before interaction with the transforming DNA is discussed.

Crit Rev Biotechnol, 1997, 17(1), 39 - 67
Xylanolytic enzymes from fungi and bacteria; Sunna A et al.; The development of new analytical techniques and the commercial availability of new substrates have led to the purification and characterization of a large number of xylan-degrading enzymes . Furthermore, the introduction of recombinant DNA technology has resulted in the selection of xylanolytic enzymes that are more suitable for industrial applications . For a successful integration of xylanases in industrial processes, a detailed understanding of the mechanism of enzyme action is, however, required . This review gives an overview of various xylanolytic enzyme systems from bacteria and fungi that have been described recently in more detail.

J Appl Microbiol, 1997 Jan, 82(1), 39 - 47
Filtration of bacteria and yeast by ultrasound-enhanced sedimentation; Hawkes JJ et al.; Continuous flow filtration of suspensions of eukaryotic cells by ultrasonic standing wave enhanced sedimentation has recently been reported . The filtration efficiency for Escherichia coli in such a filter has been characterized at frequencies of 1 and 3 MHz in the present work and compared with results for Saccharomyces cerevisiae . The yeast can be filtered at greater than 99% efficiency at a flow rate of 5 ml min-1 at either frequency . The filtration efficiency of the smaller E . coli at 3 MHz is in excess of 80% at concentrations in the region of 10(10) ml-1 but decreased at lower concentrations . However, E . coli in a mixed suspension with yeast were, because of inter-particle interactions, removed with the filtrate at an efficiency ranging from 80 to 50% over the eight orders of bacterial concentrations tested (down to 10(3) ml-1) at 3 MHz . Quantitative considerations show that poor filtration of pure suspensions of the smaller cells at the lower frequency arises because, at reasonable flow rates, the residence time is not sufficient for the cells to reach the pressure nodal cell concentration regions . The filtration efficiencies of both cell types are comparable at 3 MHz . It is suggested that the more comparable efficiencies arise because concentration regions are narrower at the high frequency and Stokes drag by the filter bulk flow inhibits sedimentation of the concentrated cells.

J Periodontal Res, 1997 Jan, 32(1 Pt 2), 200 - 5
Interactions between periodontopathogenic bacteria and cytokines; Fletcher J et al.; Cytokines produced in response to plaque bacteria clearly play a key role in the periodontal diseases . However, we know very little about the interactions between cytokines and periodontopathogenic bacteria . The aims of this study were to determine whether the key pro-inflammatory cytokines interleukin-1 beta (IL-1 beta) and IL-6 could affect the growth of Actinobacillus actinomycetemcomitans or Porphyromonas gingivalis and to determine whether these organisms could hydrolyse IL-1 beta, IL-6 or the anti-inflammatory IL-1 receptor antagonist (IL-1ra) . Culture medium containing up to 100 ng/ml of IL-1 beta or IL-6 was inoculated with A . actinomycetemcomitans (serotypes a, b and c) or P . gingivalis and growth was monitored by measuring changes in electrical conductivity every 3 min for up to 48 h . IL-1 beta, IL-6 or IL-1ra were added to culture supernatants and incubated for up to 24 h . Samples were taken at various times, analysed by SDS-PAGE and the separated proteins transferred by Western blotting to PVDF membranes and probed with anti-cytokine antibodies . None of the cytokines tested had any effect on the rate of growth or yield of A . actinomycetemcomitans or P . gingivalis . Supernatants from P . gingivalis cultures, but not those from A . actinomycetemcomitans, hydrolysed IL-1 beta, IL-6 and IL-1ra . The hydrolysate from the P . gingivalis supernatant-treated IL-1 beta was unable to stimulate the release of IL-6 from human gingival fibroblasts showing that it had lost biological activity . These results suggest that P . gingivalis can perturb the cytokine network, not only by stimulating the release of cytokines from host cells, but also by removing them from its local environment.

Appl Environ Microbiol, 1997 Jan, 63(1), 239 - 45
Evidence for production of paralytic shellfish toxins by bacteria associated with Alexandrium spp . (Dinophyta) in culture; Gallacher S et al.; A substantial proportion of bacteria from five Alexandrium cultures originally isolated from various countries produced sodium channel blocking (SCB) toxins, as ascertained by mouse neuroblastoma assay . The quantities of SCB toxins produced by bacteria and dinoflagellates were noted, and the limitations in comparing the toxicities of these two organisms are discussed . The chemical nature of the SCB toxins in selected bacterial isolates was determined as paralytic shellfish toxins by pre- and postcolumn high-performance liquid chromatography, capillary electrophoresis-mass spectrometry, and enzyme immunoassay.

Nord Med, 1997 Jan, 112(1), 10 - 3
{The body's defense against intracellular bacteria}; Tarnvik A; The separation of the two pathways of differentiation of CD4 T cells is fundamental to an understanding of host defence against intracellular bacteria . Th1 cells, but not Th2 cells, promote effective host response . Elucidation of the mechanisms responsible for the differentiation of Th1 and Th2 cells will facilitate the development of subcellular vaccines against intracellular bacteria.

Tissue Antigens, 1997 Jan, 49(1), 23 - 8
HLA-B27 presents a peptide from a polymorphic region of its own molecule with homology to proteins from arthritogenic bacteria; Garcia F et al.; A possible mechanism for the pathogenesis of HLA-B27-associated spondyloarthropathies is that peptides from arthritogenic bacteria with homology to endogenous self-peptides presented by HLA-B27, including those derived from HLA-B27 itself, could elicit an autoimmune T-cell response upon infection . We report here that an undecamer corresponding to the polymorphic region of HLA-B27 spanning residues 169-179 is presented in vivo by the B*2701, B*2704 and B*2706 subtypes, but was not detected in the B*2703-bound peptide pool . This peptide binds to B*2705 in vitro with sufficient affinity to allow its natural presentation by this subtype, but it binds with low affinity to B*2703 . In spite of homology of this peptide to proteins from arthritogenic bacteria, its binding specificity does not correlate with current evidence concerning association of HLA-B27 subtypes to ankylosing spondylitis, suggesting that presentation of this peptide is not the critical feature that determines linkage of HLA-B27 to this disease.

Biol Pharm Bull, 1997 Jan, 20(1), 47 - 53
Production of plant non-protein amino acids by recombinant enzymes of sequential biosynthetic reactions in bacteria; Saito K et al.; We constructed the co-expression vector, pFK4, in which two cDNAs encoding serine acetyltransferase (SATase) and beta-(pyrazol-1-yl)-L-alanine/L-cysteine synthase (beta-PA/CSase) from Citrullus vulgaris (watermelon) were over-expressed under the transcriptional control of T7 promoter in Escherichia coli . Accumulation of both SATase and beta-PA/CSase in soluble extracts of E . coli was confirmed by immunoblotting . The high enzymatic activities of SATase and L-cysteine synthase (CSase) were detected in cell-free extracts of E . coli carrying pFK4 . The activities of the formation of beta-PA and L-mimosine, plant non-protein amino acids, from O-acetyl-L-serine (OAS) and the precursor heterocyclic compounds, pyrazole and 3,4-dihydroxypyridine, were also found in the extracts . beta-PA was also produced in vivo from L-serine and pyrazole as precursors by E . coli cells transformed with pFK4 . beta-PA was accumulated mainly in the extra-cellular culture medium . The pronounced accumulation of L-cysteine and L-methionine was observed in the cells transformed with pFK4 . Additionally, we also constructed vectors which carried chimeric genes encoding fusion proteins of SATase and beta-PA/CSase . However, the fusion proteins tended to form insoluble inclusion bodies and thus to exhibit only weak enzymatic activities . The successful results of pFK4 shows the way to create a new sequential biosynthetic pathway of plant specific amino acids in bacterial cells by means of recombinant DNA technology.

Int J Syst Bacteriol, 1997 Jan, 47(1), 217 - 9
Transfer of the bacteriochlorophyll b-containing phototrophic bacteria Rhodopseudomonas viridis and Rhodopseudomonas sulfoviridis to the genus Blastochloris gen . nov; Hiraishi A; The phylogenetic positions of the bacteriochlorophyll (BChl) b-producing budding phototrophic bacteria Rhodopseudomonas viridis and Rhodopseudomonas sulfoviridis were studied on the basis of 16S rRNA gene sequence information . These bacteria formed a tight cluster with the genus Rhodoplanes as a sister group within the alpha-2 subgroup of the Proteobacteria . Genomic DNA-DNA hybridization assays showed that R . viridis and R . sulfoviridis were closely related but were different species . Creation of the genus Blastochloris gen . nov . is proposed to accommodate these BChl b-producing species of phototrophic bacteria.

Anal Chem, 1997 Jan 1, 69(1), 16 - 20
Genetically engineered bacteria: electrochemical sensing systems for antimonite and arsenite; Scott DL et al.; A bacterial sensing system that responds selectively to antimonite and arsenite has been investigated . The bacteria used in these studies have been genetically engineered to produce the enzyme beta-galactosidase in response to these ions . This is accomplished by using a plasmid that incorporates the gene for beta-galactosidase (reporter gene) under the control of the promoter of the ars operon . This plasmid also encodes for the ArsR protein, a regulatory protein of the ars operon, which, in the absence of antimonite or arsenite, restricts the expression of beta-galactosidase . In the presence of antimonite or arsenite the ArsR protein is released from the operator/ promoter region of the ars operon and beta-galactosidase is expressed . The activity of this enzyme was monitored electrochemically using p-aminophenyl beta-D-galactopyranoside as the substrate . The bacterial sensing system responds selectively to arsenite and antimonite (and to a lesser extent arsenate) and shows no significant response to phosphate, sulfate, nitrate, and carbonate.

Oral Dis, 1996 Dec, 2(4), 253 - 62
Rheumatoid factor from periodontitis patients cross-reacts with epitopes on oral bacteria; The J et al.; OBJECTIVES: The objective of this study was to determine the antigenic specificity of rheumatoid factor (RF) that had previously been reported in the serum of patients with periodontitis . DESIGN: IgM-RF was isolated from the serum of five RF-seropositive rheumatoid arthritis patients and 14 RF-seropositive periodontitis and examined for specificity to human IgG and selected oral bacteria . METHODS: IgM-RF was prepared by affinity chromatography on human IgG columns . Human IgG antibody to Capnocytophaga gingivalis, Fusobacterium nucleatum, and Actinobacillus actinomycetemcomitans was isolated by binding and elution of antibody from the bacteria, followed by purification using a rabbit anti-IgG affinity column . MAIN OUTCOME MEASURE: Binding of the isolated IgM-RF was determined using an enzyme-linked immunosorbent assay (ELISA) . The antigens used for detection of binding included isolated human IgG, human IgG antibody bound to the bacteria, and the bacteria alone . Inhibition of the IgM-RF binding with IgG or Fc gamma was used to assess the specificity of the reactivity with IgG and/or the bacteria . RESULTS: The results showed that the IgM-RF reacted with polyclonal human IgG nonspecifically bound to microtiter plates . The reactivity of the IgM-RF was increased when incubated with IgG that bound as antibody to C . gingivalis, F . nucleatum or A . actinomycetemcomitans . However, the IgM-RF did not bind with increased intensity to the specific IgG antibody preparations or to IgG preparations lacking antibody to these micro-organisms . Additionally, the IgM-RF preparations bound to surface components of both C . gingivalis and F . nucleatum . Blocking studies showed that Fc gamma but not IgG inhibited IgM-RF binding to both micro-organisms . CONCLUSIONS: These findings indicate that the RF detected in the serum of some periodontitis patients may be elicited by certain micro-organisms in the subgingival plaque . Furthermore, C . gingivalis and F . nucleatum appear to express surface antigen epitopes that are antigenically related to determinants on IgG can induce cross-reactive IgM-RF.

J Anat, 1996 Dec, 189 ( Pt 3), 537 - 48
The relationship between gut-derived bacteria and the development of the multiple organ dysfunction syndrome; Nieuwenhuijzen GA et al.; Abnormal colonisation, infections of gut origin and bacterial translocation are all signs of gut failure that have been hypothesised as being implicated in the pathogenesis of the multiple organ dysfunction syndrome (MODS) . We have summarised published experimental and clinical studies that have tried to correlate the occurrence or prevention of these phenomena with the development of MODS . We conclude that in some patients loss of intestinal barrier function or the onset of infection precedes the development of MODS . In other patients, however, this relationship is not so clear and it seems that these are epiphenoma of critical illness and may reflect a failure of the host's immune and mechanical defence systems . The causal relationship between these phenomena and the development of MODS is complex and needs further clarification.

Appl Environ Microbiol, 1996 Dec, 62(12), 4499 - 503
Use of potassium depletion to assess adaptation of ruminal bacteria to ionophores; Lana RP et al.; When mixed ruminal bacteria from cattle fed timothy hay were suspended in a medium containing a low concentration of potassium, monensin and lasalocid catalyzed a rapid depletion of potassium from cells . The ionophore-mediated potassium depletion was concentration dependent, and it was possible to describe the relationship with saturation constants . Mixed ruminal bacteria never lost more than 50% of their potassium (Kmax = 46%), and the concentrations of monensin and lasalocid needed to cause half-maximal potassium depletion (Kd) were 178 and 141 nM, respectively . When cattle were fed 350 mg of monensin per day, the ratio of ruminal acetate to propionate decreased from 4.2 to 2.9, and the Kd of monensin was eightfold greater than the value for mixed ruminal bacteria from control animals . Monensin supplementation also caused a twofold increase in the Kd of lasalocid . Lasalocid supplementation (350 mg per day) had no effect on the ruminal acetate-to-propionate ratio, but it caused a twofold increase in the Kd values of monensin and lasalocid . Increases in Kd occurred almost immediately after ionophore was added to the ration, and the Kd values returned to their prefeeding values within 14 days of withdrawal . Ionophore supplementation had no effect on the Kmax values, and approximately 50% of the population was always highly ionophore resistant . Because the Kd values of even adapted ruminal bacteria were low (< 1.5 microM), it appears that a large proportion of the ruminal ionophore is bound nonselectively to feed particles or ionophore-resistant bacteria.

Infect Immun, 1996 Dec, 64(12), 5384 - 9
Effect of in vitro infection of human monocytes with low numbers of Mycobacterium tuberculosis bacteria on monocyte apoptosis; Durrbaum-Landmann I et al.; The effect of Mycobacterium tuberculosis H37Rv on spontaneous apoptosis of human monocytes from healthy donors in vitro was investigated . Infection with low numbers of viable M . tuberculosis bacteria prevented spontaneously occurring apoptosis in monocytes . Our data suggest that apoptosis of monocytes appears to be negatively associated with the presence of tumor necrosis factor alpha.

Gene, 1996 Nov 7, 179(1), 157 - 62
Translation attenuation regulation of chloramphenicol resistance in bacteria--a review; Lovett PS; The chloramphenicol (Cm)-inducible cat and cmlA genes are regulated by translation attenuation, a regulatory device that modulates mRNA translation . In this form of gene regulation, translation of the CmR coding sequence is prevented by mRNA secondary structure that sequesters its ribosome-binding site (RBS) . A translated leader of nine codons precedes the secondary structure, and induction results when a ribosome becomes stalled at a specific site in the leader . Here we demonstrate that the site of ribosome stalling in the leader is selected by a cis effect of the nascent leader peptide on its translating ribosome.

Bull Tokyo Dent Coll, 1996 Nov, 37(4), 183 - 7
Electrochemical bacteriocidal action based on electron transfer of salivary bacteria; Ohne M et al.; Based upon the observation that most oral bacteria are negatively charged, we attempted to restrain the development of oral bacteria in saliva by applying a constant electric potential to an electrode . The development of salivary bacteria was clearly restrained by applying 0.74V electric current for 30 min . This restraint was in inverse proportion to the concentration of the suspension of salivary bacteria . The authors hypothesize that the electrochemical restraining was based on electron transfer between the salivary bacteria and the electrode.

Zhonghua Min Guo Xiao Er Ke Yi Xue Hui Za Zhi, 1996 Nov-Dec, 37(6), 466 - 70
Bacteria-associated hemophagocytic syndrome in childhood acute lymphoblastic leukemia: report of two cases; Hsiao CC et al.; Two children with acute lymphoblastic leukemia presenting with cellulitis and sepsis are described . Both presented as having hemophagocytic syndrome with the manifestations of prolonged fever, jaundice, pancytopenia, coagulopathy and histiocytic proliferation with hemophagocytosis in their bone marrows . It is similar to the virus-associated hemophagocytic syndrome (VAHS), except for the absences of lymphadenopathy, skin rash and hepatosplenomegaly . Concomitant virus infections were excluded in these two cases . Both patients' conditions improved after appropriate antibiotics and intravenous immunoglobulin therapy . The prognosis seemed better in bacteria-associated hemophagocytic syndrome (BAHS) than in VAHS even in immunocompromised patients.

Vet Immunol Immunopathol, 1996 Nov, 54(1-4), 309 - 19
T lymphocyte mediated protection against facultative intracellular bacteria; Splitter G et al.; Acquired immunity against intracellular bacteria is T cell dependent . T cells play a major role in protection against intracellular bacteria, but bacterial antigens recognized by T cells have been studied less extensively than bacterial antigens recognized by B cells . Using T lymphocytes from animals immunized against Brucella abortus, we have screened a bacterial genomic library for genes encoding antigens recognized by T cells . Lymphocytes that proliferated to B . abortus proteins were characterized for phenotype and cytokine activity . Bovine and murine lymphocytes recognized common bacterial antigens and possessed similar cytokine profiles, suggesting an analogous immune response in these two animal species . In vivo protection afforded by a particular cell type is dependent on the bacterial antigens presented and mechanisms of antigen presentation . MHC class I and class II gene knockout animals infected with B . abortus have demonstrated that protection to B . abortus is especially dependent on CD8+ T cells . Knowing the cells required for protection, vaccines can be designed to elicit the protective subset of lymphocytes . Currently, we are testing several recombinant B . abortus proteins using different immunization strategies . Finally, bacterial genes activated following intracellular phagocytosis are being examined using a novel, reporter system adapted to B . abortus.

FEMS Immunol Med Microbiol, 1996 Nov, 16(1), 31 - 8
Anti-endotoxin antibodies directed against Escherichia coli R-1 oligosaccharide core-tetanus toxoid conjugate bind to smooth, live bacteria and smooth lipopolysaccharides and attenuate their tumor necrosis factor stimulating activity; Lugowski C et al.; The reactivity of anti-OS R1-tetanus toxoid serum with various smooth and rough lipopolysaccharides have been determined in enzyme-linked immunosorbent assay (ELISA) and with intact, live smooth bacterial cells in flow cytometry . All tested smooth lipopolysaccharides of R1 core type belonging to nine different O-serotypes reacted strongly with anti-conjugate antibodies . Flow cytometry showed that anti-core antibodies labelled more than 95% of bacterial cells with high intensity of fluorescence . The anti-conjugate serum was able to react with free form of smooth lipopolysaccharides and to inhibit their TNF stimulation activity in in vitro and in vivo models.

Curr Microbiol, 1996 Nov, 33(5), 306 - 11
In vitro metabolism of the stereoisomers of 2,6-diaminopimelic acid by mixed rumen protozoa and bacteria; El-Waziry AM et al.; Formation of lysine from stereoisomers (SI) of 2,6-diaminopimelic acid (DAP) and the epimerization between the three SI of DAP (DAP-SI) by rumen protozoa and bacteria were examined . Mixed rumen protozoa (P) and bacteria (B) were isolated from the rumen of goats given a concentrate and hay cubes and incubated separately with and without a mixture and a single one of the three DAP-SI . In P suspensions, mixed DAP-SI decreased by 10.59% as a whole and converted mainly to lysine by 8.41% during 12 h incubation . When meso-, L- and D-DAP were added singly to the media, the results showed that each DAP-SI interconverted and produced lysine . This means that mixed rumen protozoa have an ability to synthesize lysine from not only meso-DAP but also from D- and L-DAP, though probably via meso-DAP, and hence have DAP epimerase activities for the reversal conversion of each DAP-SI . This is the first discovery to show the interconversion of DAP-SI and synthesis of lysine from them by protozoa . In B suspensions, mixed DAP-SI decreased by 10.92% as a whole and converted to lysine by 4.20% during 12 h incubation . When a single DAP-SI was added to the media, meso-, L- and D-DAP were interconverted and then converted to lysine by the rumen bacteria as well as the protozoa . This also means that mixed rumen bacteria have DAP epimerase activities to interconvert DAP-SI and have an ability to synthesize lysine from not only meso-DAP but also from L- and D-DAP, and this is also the first finding in rumen bacteria.

J Mol Evol, 1996 Nov, 43(5), 523 - 7
The ruminant digestion model using bacteria already employed early in evolution by symbiotic molluscs; Jolles J et al.; The purification and some molecular properties of six lysozymes from the gills of different mytilids and vesicomyids are described: they belong to the previously described Invertebrate lysozyme family . The predominance of the bacterial nutrition in these organisms seems to necessitate the presence of a lysozyme as in the case of the ruminant digestion model.

J Biol Chem, 1996 Oct 25, 271(43), 26677 - 83
Expression of soluble human beta-globin chains in bacteria and assembly in vitro with alpha-globin chains; Yamaguchi T et al.; Authentic soluble human beta-globin chains were produced in Escherichia coli using an expression plasmid (pHE2beta) containing full-length cDNAs coding for human beta-globin chain and methionine aminopeptidase . Spectral properties of the purified beta-globin were identical to those of authentic beta-globin . Soluble beta-globin showed low (16 kDa) and high molecular mass (32 kDa) forms that could be separated by gel filtration chromatography . SDS-polyacrylamide gel electrophoresis and electrospray mass spectrometry revealed the 32-kDa species was dimeric beta-globin formed by an intermolecular disulfide bond, while the 16-kDa species was authentic monomeric beta-globin . Monomeric forms of beta-globin, like authentic native beta-globin, formed tetrameric hemoglobin (Hb) A (alpha2beta2) in vitro upon incubation with alpha-globin, while dimeric forms did not . When beta-globin dimers, however, were converted to monomers by incubation with dithiothreitol, the beta-globin chain monomers assembled with alpha-globin and formed hemoglobin tetramers . alpha-Globin was more thermally unstable than beta-globin, while assembled tetramers promoted higher stability . Disulfide-bonded beta-globin dimers showed a slight increase in thermal stability compared with beta-globin; however, dimers were still more unstable than tetrameric Hb A . These results indicate that presence of alpha chains favors assembly with beta-globin, beta-beta dimers cannot bind alpha chains, and that Hb A tetramer formation results in the most thermally stable species.

J Am Vet Med Assoc, 1996 Oct 15, 209(8), 1468 - 9
Abomasal bloat associated with Sarcina-like bacteria in goat kids; DeBey BM et al.; An epizootic of abdominal tympany in goat kids as a result of abomasal bloat associated with a short duration of clinical signs was fatal in over 200 kids . Histologic examination of sections of abomasum revealed high numbers of bacteria that were morphologically identical to Sarcina sp . Sarcina sp are anaerobic, gas-producing organisms that could cause abomasal bloat . Other reports have proposed that abomasal bloat is caused by abnormal abomasal flora; we propose that in the goat kids reported here, Sarcina sp may represent the abnormal flora.

FEMS Microbiol Lett, 1996 Oct 15, 144(1), 95 - 102
Phylogenetic analysis of tnpR genes in mercury resistant soil bacteria: the relationship between DNA sequencing and RFLP typing approaches; Holt RJ et al.; The diversity of resolvase (tnpR) genes carried by a number of mercury resistant soil bacteria has been investigated by DNA sequencing . The resulting DNA sequence information was compared to previously published tnpR DNA sequences and to previously published restriction fragment length polymorphism (RFLP) data, permitting the relationships between DNA sequencing and RFLP approaches to be studied by the use of phylogenetic trees . DNA maximum likelihood and DNA parsimony were used to construct a variety of phylogenetic trees . DNA sequencing confirmed the validity of RFLP analysis and highlighted the importance of restriction endonuclease choice upon the resulting RFLP patterns and dendrogram topology . The tnpR genes of two previously uncharacterised mercury resistant bacteria, T2-7 and T2-12 were also studied . DNA sequence data placed T2-7 in a previously described gene class, tnpR-D and T2-12 in a new gene class, tnpR-F . The significance of this data with respect to the recombination and evolution events occurring within bacterial populations are discussed.

Arch Oral Biol, 1996 Oct, 41(10), 959 - 64
Use of N-phenylmethazonium methosulphate oxidation of NADH in the quantification of oxygen uptake by oral bacteria under open-system conditions; Traudt M et al.; Technically, open systems are more suited than closed systems for the measurement of oxygen uptake by bacteria present at high cell densities as in dental plaque . Moreover, measurements are easier to perform and can be done faster and continuously . However, quantifications is more difficult and, except for steady-state conditions, has been semiquantitative . The stoichiometric oxidation of NADH by N-phenylmethazonium methosulphate (PMS) is a reaction used here to develop a formula that overcomes this problem and makes it possible to relate quantitatively the pO2 measured easily with an oxygen electrode to the amount of oxygen utilized by respiring bacteria provided with a given amount of substrate . The approach and formula consist of the summing of (i) the oxygen decrease observed during the period of bacterial oxygen consumption and (ii) the oxygen simultaneously entering from the atmosphere . To quantify the entry component, the rate of oxygen diffusion into the mixture needed to be determined: this was done by reducing or exhausting the oxygen content of the medium in various ways and determining the rate constant of atmospheric oxygen entry . The relation between the logarithm of the oxygen concentration (determined from pO2 values using the PMS-NADH reaction) and point of time in the oxygen resaturation process proved to be linear . This enabled calculation of a diffusion rate constant, k, for use in the oxygen utilization formula . The validity of this method for quantification of oxygen use was tested by comparing oxygen consumption determined from the pO2 tracing and the derived formula to the oxygen consumed when fixed amounts of NADH are oxidized by PMS . When oxygen uptake/substrate utilization molar ratios were calculated for each of several NADH concentrations, the resulting values were almost identical . The method proved reliable over most of the oxygen concentration range possible in this system.

Oral Microbiol Immunol, 1996 Oct, 11(5), 332 - 6
Effect of oral bacteria on peripheral blood leukocyte interleukin-6 and soluble interleukin-6 receptor production; Lindemann RA et al.; To determine the effect of pathogenic oral bacteria on interleukin 6 (IL-6) and soluble IL-6 receptor production, we measured their release by human peripheral blood mononuclear cells in vitro . Unseparated peripheral blood mononuclear cells, peripheral blood lymphocytes (monocyte depleted), pure T cells, or monocytes were cultured with Actinobacillus actinomycetemcomitans, Capnocytophaga gingivalis, Capnocytophaga ochracea, Fusobacterium nucleatum or Porphyromonas gingivalis for 24 h . Supernatants were tested for IL-6 and soluble IL-6 receptor by enzyme-linked immunosorbent assay . Only monocytes and peripheral blood mononuclear cells responded with significant IL-6 release in the presence of all bacteria tested . However, peripheral blood lymphocytes were capable of producing IL-6 when activated by phytohemagglutinin or IL-2 followed by bacteria, though substantially less than cultures containing monocytes . No bacteria tested increased soluble IL-6 receptor release over spontaneous soluble IL-6 receptor release . We conclude that monocytes release IL-6 after contact with oral pathogens; however, soluble IL-6 receptor from T cells and monocytes is constitutively produced and may modulate IL-6 actions.

Curr Opin Biotechnol, 1996 Oct, 7(5), 500 - 4
Expression in bacteria other than Escherichia coli; Billman-Jacobe H; Although many bacteria are used for the expression of foreign genes, there is still a need to develop better expression systems . Advances have been made in the stabilization of gene maintenance and in the control of expression, therefore increasing the potential usefulness of some of these bacteria.

J Clin Periodontol, 1996 Oct, 23(10), 955 - 9
Discrepancy between culture and DNA probe analysis for the detection of periodontal bacteria; van Steenbergen TJ et al.; The purpose of this study was to compare a commercially available DNA probe technique with conventional cultural techniques for the detection of Actinobacillus actinomycetemcomitans, Porphyromonas gingivalis and Prevotella intermedia in subgingival plaque samples . Samples from 20 patients with moderate to severe periodontitis were evaluated at baseline and during a 15 months period of periodontal treatment . Paperpoints from 4 periodontal pockets per patient were forwarded to Omnigene for DNA probe analysis, and simultaneously inserted paperpoints from the same pockets were analyzed by standard culture techniques . In addition, mixed bacterial samples were constructed harbouring known proportions of 25 strains of A . actinomycetemcomitans, P . gingivalis and P . intermedia each . A relatively low concordance was found between both methods . At baseline a higher detection frequency was found for A . actinomycetemcomitans and P . gingivalis for the DNA probe technique; for P . intermedia the detection frequency by culture was higher . For A . actinomycetemcomitans, 21% of the culture positive samples was positive with the DNA probe . Testing the constructed bacterial samples with the DNA probe method resulted in about 16% false positive results for the 3 species tested . Furthermore, 40% of P . gingivalis strains were not detected by the DNA probe . The present data suggest that at least part of the discrepancies found between the DNA probe technique used and cultural methods are caused by false positive and false negative DNA probe results . Therefore, the value of this DNA probe method for the detection of periodontal pathogens is questionable.

Biochem Mol Biol Int, 1996 Oct, 40(2), 243 - 52
Structure of bacteriochlorophyll aggregates in chlorosomes of green bacteria: a spectral hole burning study; Novoderezhkin VI et al.; Exciton level structure, homogenous absorption and hole-burning spectra were calculated for different models of bacteriochlorophyll aggregation in chlorosomal antennae of green bacteria . It was demonstrated that none of the earlier proposed models of noninteracting linear bacteriochlorophyll aggregates and linear bacteriochlorophyll chains assembling in tubular aggregates with high density of packing, exhibits the in vivo exciton level structure revealed by hole-burning experiments on intact cells of green bacteria . The models of linear exciton-coupled bacteriochlorophyll chains with a low packing density, approximating that in vivo, were proposed as alternative, to obtain the main spectral features found in natural antennae.

J Exp Med, 1996 Oct 1, 184(4), 1251 - 8
A T cell receptor V alpha domain expressed in bacteria: does it dimerize in solution?
Plaksin D, Chacko S, McPhie P, Bax A, Padlan EA, Margulies DH.
To evaluate the potential for dimerization through a particular T cell receptor (TCR) domain, we have cloned the cDNA encoding a TCR V alpha from a hybridoma with specificity for the human immunodeficiency virus (HIV) envelope glycoprotein 120-derived peptide P18-110 (RGPGRAFVTI) bound to the murine major histocompatibility complex (MHC) class I molecule, H-2Dd . This cDNA was then expressed in a bacterial vector, and protein, as inclusion bodies, was solubilized, refolded, and purified to homogeneity . Yield of the refolded material was from 10 to 50 mg per liter of bacterial culture, the protein was soluble at concentrations as high as 25 mg/ml, and it retained a high level of reactivity with an anti-V alpha 2 monoclonal antibody . This domain was monomeric both by size exclusion gel chromatography and by sodium dodecyl sulfate polyacrylamide gel electrophoresis . Circular dichroism spectra indicated that the folded V alpha domain had secondary structure similar to that of single immunoglobulin or TCR domains, consisting largely of beta sheet . Conditions for crystallization were established, and at least two crystal geometries were observed: hexagonal bipyramids that failed to diffract beyond approximately 6 A, and orthorhombic crystals that diffracted to 2.5 A . The dimerization of the V alpha domain was investigated further by solution nuclear magnetic resonance spectroscopy, which indicated that dimeric and monomeric forms of the protein were about equally populated at a concentration of 1 mM . Thus, models of TCR-mediated T cell activation that invoke TCR dimerization must consider that some V alpha domains have little tendency to form homodimers or multimers.

Proc Natl Acad Sci U S A, 1996 Sep 3, 93(18), 9553 - 8
Cytokine-treated human neutrophils contain inducible nitric oxide synthase that produces nitration of ingested bacteria; Evans TJ et al.; Although the production of NO within rodent phagocytes is well-characterized, its production and function within human phagocytes are less clear . We show here that neutrophils within human buffy coat preparations stimulated with a mixture of interleukin 1, tumor necrosis factor alpha, and interferon gamma contain inducible NO synthase mRNA and protein, one of the enzymes responsible for NO production . The protein colocalizes with myeloperoxidase within neutrophil primary granules . Using an inhibitor of NO synthase, L-N-monomethyl arginine, we show that activity of this enzyme is required for the formation of nitrotyrosine around phagocytosed bacteria, most likely through the intermediate production of peroxynitrite, a reaction product of NO and superoxide anions.

Med Hypotheses, 1996 Sep, 47(3), 179 - 82
An electromagnetic coupling hypothesis to explain the proton translocation mechanism in mitochondria, bacteria and chloroplasts; Menendez RG; Three different mechanisms have been proposed for energy transfer between electron transport and ATP synthesis . The chemiosmotic hypothesis is widely accepted as the central organizing principle for the process in mitochondria bacteria and chloroplasts . A very important problem still unsolved is the manner in which the electron transport in the inner membrane pumps protons from the mitochondrial matrix to the exterior . In order to provide clues to the mechanism of proton translocation, and without any contradiction with the chemiosmotic model, the author wishes to put forward an electromagnetic coupling hypothesis based on the characteristics of the electromagnetic field . The new hypothesis has novel features which could be of biological interest.

Mol Microbiol, 1996 Sep, 21(5), 1049 - 60
Programmed cell death in bacteria: translational repression by mRNA end-pairing; Franch T et al.; The hok/sok and pnd systems of plasmids R1 and R483 mediate plasmid maintenance by killing plasmid-free cells . Translation of the exceptionally stable hok and pnd mRNAs is repressed by unstable antisense RNAs . The different stabilities of the killer mRNAs and their cognate repressors explain the onset of translation in plasmid-free cells . The full-length hok and pnd mRNAs are inert with respect to translation and antisense RNA binding . We have previously shown that the mRNAs contain two negative translational control elements . Thus, the mRNAs contain upstream anti-Shine-Dalgarno elements that repress translation by shielding the Shine-Dalgarno elements . The mRNAs also contain fold-back-inhibition elements (fbi) at their 3' ends that are required to maintain the inert mRNA configuration . Using genetic complementation, we show that the 3' fbi elements pair with the very 5' ends of the mRNAs . This pairing sets the low rate of 3' exonucleolytical processing, which is required for the accumulation of an activatable pool of mRNA . Unexpectedly, the hok and pnd mRNAs were found to contain translational activators at their 5' ends (termed tac) . Thus, the fbi elements inhibit translation of the full-length mRNAs by sequestration of the tac elements . The fbi elements are removed by 3' exonucleolytical processing . Mutational analyses indicate that the 3' processing triggers refolding of the mRNA 5' ends into translatable configurations in which the 5' tac elements base pair with the anti-Shine-Dalgarno sequences.

J Invertebr Pathol, 1996 Sep, 68(2), 141 - 5
Effect of cucurbitacin D on in vitro growth of Xenorhabdus and Photorhabdus spp., symbiotic bacteria of entomopathogenic nematodes; Barbercheck ME et al.; In vitro assays were conducted to determine the effect of cucurbitacin D, an oxygenated tetracyclic triterpenoid found in cucurbits, on the growth of Xenorhabdus isolated from Steinernema carpocapsae (All, Mexican, Agriotos strains), Steinernema riobravis, Steinernema glaseri (NC strain, strain 27), and Photorhabdus from Heterorhabditis bacteriophora (NC, Lewiston strains), and Heterorhabditis sp . (FL2122 strain) . Cucurbitacin D inhibited the growth of four isolates, had no effect on the growth of four isolates, and stimulated the growth of one isolate . Results are discussed in relation to progeny production of entomopathogenic nematodes from insects that have eaten plant material containing cucurbitacin D . This is the first report of an effect of a plant secondary compound on the bacterial symbionts of entomopathogenic nematodes.

Arch Microbiol, 1996 Sep, 166(3), 151 - 9
Formation of the light-harvesting complex I (B870) of anoxygenic phototrophic purple bacteria; Drews G; The light-harvesting (LH) complex I (B870) of anoxygenic photosynthetic purple bacteria is the oligomeric form of its subunit B820 consisting of the low-molecular-weight polypeptides alpha, beta, bacteriochlorophyll (BChl), and carotenoids in the stoichiometric ratio {alpha1 beta1 (BChl2) Crt1-2}n . LHI surrounds the photochemical reaction center (RC) . The major absorption band of the LHI complex is species-specific and is found at 870-890 nm; those of the subunit and the monomeric BChl a (dissolved in methanol) absorb at 820 and 770 nm, respectively . The isolated LHI complex can be reversibly dissociated to the B820 subunit or to the polypeptides and pigments by addition of detergents . Reconstitution of the B820 or the functional B870 complex is still possible after partial truncation of the N- or C-terminal regions of the alpha- or beta-polypeptide or of the beta-polypeptide only . The minimal structural requirements for reconstitution of a spectrally wild-type form after truncation of the polypeptides and/or modifications of the BChl molecule are described . The insertion of the LHIalpha- and LHIbeta-polypeptides into the membrane and the in vivo assembly of LHI, studied in a cell-free system and in whole cells of Rhodobacter capsulatus, depend on the primary structures of both polypeptides, BChl, the chaperones DnaK and GroEL, membrane-bound proteins, and energized membranes . Exchanges, deletions, or insertions of amino acyl residues, especially in the conserved region of the N-terminus of the LHIalpha-polypeptide, prevent or reduce the efficiency and stability of the LHI assembly . Therefore, reconstitution of LHI in a detergent micelle does not exactly reproduce the formation of the LHI complex in the photosynthetic membrane in vivo . The N-terminal domains play a crucial role in the formation of the oligomeric protein scaffold and of the pigment array.Facultatively phototrophic bacteria such as Rhodospirillum (Rsp.) rubrum or Rhodobacter (Rba.) capsulatus can adjust to changes in oxygen tension, light intensity, temperature, and substrates to grow under chemotrophic or phototrophic conditions . The photosynthetic apparatus (PSA), localized mainly on intracytoplasmic membranes (ICM), is usually synthesized only under low oxygen partial pressure . The cellular amount and composition of the PSA are modified upon changing light intensity in relation to cell growth (Drews and Golecki 1995) . The morphogenesis of cellular structures like ICM is quite different from self-assembly . Self-assembly is a reversible process of aggregation of the constituents of a complex structure without protein synthesis and is driven by weak or strong forces in the interactions of the constituents . Morphogenesis results from the interplay of numerous gene products and the cellular organization and is always dependent upon pre-existent structures (Harold 1995) . The morphogenesis of the photosynthetic membrane in purple bacteria has been studied in its different steps . The regulation at the transcriptional and post-transcriptional levels in purple bacteria, and the structure and morphogenesis of the ICM have been described recently (Armstrong 1995; Bauer 1995; Biel 1995; Drews and Golecki 1995; Klug 1995).In this mini-review, I will focus on the minimal requirements for the in vitro assembly of light-harvesting (LH) complex I (B870) from its constituents in detergent micelles and compare the results with observations on the complex process of targeting and import of LHI polypeptides into the membrane and assembly of B870.

Oral Microbiol Immunol, 1996 Aug, 11(4), 242 - 7
Fc gamma-binding bacteria in periodontal lesions; Hillestad M et al.; The proportion of bacteria exhibiting surface Fc gamma-binding proteins was determined in periodontal pockets of 20 patients diagnosed with periodontal disease and in subgingival areas of 20 patients without periodontal lesions . Bacterial smears were examined by fluorescence microscopy based on DNA staining (Hoechst 33256) and staining of Fc gamma-binding proteins by human biotin-labelled Fc gamma and Texas red-conjugated streptavidin . Fc gamma-binding proteins were observed in all smears from the patients diagnosed with periodontitis, and in a majority of the smears high proportions of the bacteria were positive for Fc gamma-binding proteins . In contrast, most smears from patients without periodontal lesions included low or undetectable proportions of bacteria with Fc gamma-binding proteins.

J Bacteriol, 1996 Aug, 178(15), 4742 - 6
Glutathione amide and its perthiol in anaerobic sulfur bacteria; Bartsch RG et al.; Chromatium species produced the novel biological thiol glutathione amide, gamma-L-glutamyl-L-cysteinylglycine amide (GASH), when grown photoheterotrophically . GASH was largely converted to the corresponding perthiol during photoautotrophic growth on sulfide, suggesting that GASH may have a function in anaerobic sulfide metabolism . This unprecedented form of glutathione metabolism was probably present in anaerobic ancestors of modern cyanobacteria and purple bacteria.

J Med Microbiol, 1996 Aug, 45(2), 153 - 4
A novel simple method for quantifying bacteria from endotracheal aspirates; Flanagan PG et al.; A convenient dipstrip method (Bacteruritest; Mast Diagnostics) for bacterial quantification was evaluated with 42 endotracheal aspirates . For 31 specimens, the dipstrip method yielded counts within a 10-fold range of surface plate counts . Two specimens yielded counts by the dipstrip within a 100-fold range of plate counts . Six specimens yielded confluent growth at the greatest dilution tested by the dipstrip method, and counts > 10(10) cfu/ml in the surface plate method . Three specimens yielded no detectable growth by the dipstrip and surface plate counts < 10(2) cfu/ml . Dipstrips provide a cheap, convenient method for the routine quantification of the bacterial load in endotracheal aspirates.

FEBS Lett, 1996 Jul 29, 390(3), 245 - 8
Macromolecular crowding and the mandatory condensation of DNA in bacteria; Zimmerman SB et al.; Cellular DNA in bacteria is localized into nucleoids enclosed by cytoplasm . The forces which cause condensation of the DNA into nucleoids are poorly understood . We suggest that direct and indirect macromolecular crowding forces from the surrounding cytoplasm are critical factors for nucleoid condensation, and that within a bacterial cell these crowding forces are always present at such high levels that the DNA is maintained in a condensed state . The DNA affected includes not only the preexisting genomic DNA but also DNA that is newly introduced by viral infection, replication or other means.

J Clin Invest, 1996 Jul 15, 98(2), 572 - 83
Infection of human intestinal epithelial cells with invasive bacteria upregulates apical intercellular adhesion molecule-1 (ICAM)-1) expression and neutrophil adhesion; Huang GT et al.; The acute host response to gastrointestinal infection with invasive bacteria is characterized by an accumulation of neutrophils in the lamina propria, and neutrophil transmigration to the luminal side of the crypts . Intestinal epithelial cells play an important role in the recruitment of inflammatory cells to the site of infection through the secretion of chemokines . However, little is known regarding the expression, by epithelial cells, of molecules that are involved in interactions between the epithelium and neutrophils following bacterial invasion . We report herein that expression of ICAM-1 on human colon epithelial cell lines, and on human enterocytes in an in vivo model system, is upregulated following infection with invasive bacteria . Increased ICAM-1 expression in the early period (4-9 h) after infection appeared to result mainly from a direct interaction between invaded bacteria and host epithelial cells since it co-localized to cells invaded by bacteria, and the release of soluble factors by epithelial cells played only a minor role in mediating increased ICAM-1 expression . Furthermore, ICAM-1 was expressed on the apical side of polarized intestinal epithelial cells, and increased expression was accompanied by increased neutrophil adhesion to these cells . ICAM-1 expression by intestinal epithelial cells following infection with invasive bacteria may function to maintain neutrophils that have transmigrated through the epithelium in close contact with the intestinal epithelium, thereby reducing further invasion of the mucosa by invading pathogens.

J Dairy Sci, 1996 Jul, 79(7), 1237 - 43
The effect of amino nitrogen on the energetics of ruminal bacteria and its impact on energy spilling; Van Kessel JS et al.; The predominant ruminal bacteria that were obtained from a 10(8) dilution of ruminal fluid could be maintained as a mixed population for long periods as long as the bacteria were provided with a complex mixture of carbohydrates . Growth of predominant ruminal bacteria in carbohydrate-limited, ammonia-excess, continuous cultures (0.07/h) had a low requirement for maintenance energy, but the nongrowth energy dissipation of ammonia-limited, carbohydrate-excess, predominant ruminal bacteria was approximately 10-fold higher (0.96 vs . 0.09 mg of hexose equivalent/mg of protein per h, respectively) . Mathematical derivations indicated that this additional nongrowth energy dissipation could be accommodated by an energy spilling function that was independent of the growth rate . Peptides and amino acids had little impact on the yield of carbohydrate-limited, ammonia-excess, continuous cultures (0.07/ h), but amino N greatly increased the growth rate and yield of excess-energy batch cultures . The change in growth rate and yield that was dependent on amino N indicated that the energy-excess batch cultures had the same capacity to spill energy as did the ammonia-limited, carbohydrate-excess, predominant ruminal bacteria (0.80 vs . 0.86 mg of hexose equivalent/mg of protein per h, respectively) . When the energy-excess batch cultures were provided with amino N, the growth rate increased, the difference in anabolic and catabolic rates was smaller, and less energy was spilled.

Biochem Mol Biol Int, 1996 Jul, 39(4), 671 - 8
The effects of decyl aurachins C and D on the respiratory electron flow of facultative phototrophic bacteria; Romagnoli S et al.; Decyl aurachins C and D are two synthetic compounds related to the natural products aurachins C and D extracted from Stigmatella aurantiaca . Titrations of a range of partial respiratory activities in membranes from facultative phototrophs indicate that decyl aurachin C is more effective than aurachin D in inhibiting the quinol oxidase . Decyl aurachin C also affects the NADH-ubiquinone oxidoreductase of Rhodobacter capsulatus and the cytochrome bc1 complexes of Rb.capsulatus and Rhodospirillum centenum . Titration of the light-induced respiration in Rsp.centenum allowed us to estimate an upper limit for the ubiquinol oxidase concentration of 1.5 +/- 0.2 nmol/mg protein, or a ubiquinol oxidase/cytochrome c oxidase ratio of 3:1.

Appl Environ Microbiol, 1996 Jul, 62(7), 2621 - 8
Detection and characterization of broad-host-range plasmids in environmental bacteria by PCR; Gotz A et al.; Primer systems for PCR amplification of different replicon-specific DNA regions were designed on the basis of published sequences for plasmids belonging to the incompatibility (Inc) groups IncP, IncN, IncW, and IncQ . The specificities of these primer systems for the respective Inc groups were tested with a collection of reference plasmids belonging to 21 different Inc groups . Almost all primer systems were found to be highly specific for the reference plasmid for which they were designed . In addition, the primers were tested with plasmids which had previously been grouped by traditional incompatibility testing to the IncN, IncW, IncP, or IncQ group . All IncQ plasmids gave PCR products with the IncQ primer systems tested . However, PCR products were obtained for only some of the IncN, IncP, and IncW group plasmids . Dot blot and Southern blot analyses of the plasmids revealed that PCR-negative plasmids also failed to hybridize with probes derived from the reference plasmids . The results indicated that plasmids assigned to the same Inc group by traditional methods might be partially or completely different from their respective reference plasmids at the DNA level . With a few exceptions, all plasmids related to the reference plasmid at the DNA level also reacted with the primer systems tested . PCR amplification of total DNA extracted directly from different soil and manure slurry samples revealed the prevalence of IncQ- and IncP-specific sequences in several of these samples . In contrast, IncN- and IncW-specific sequences were detected mainly in DNA obtained from manure slurries.

Proc Natl Acad Sci U S A, 1996 Jun 11, 93(12), 6124 - 8
Novel human DNA alkyltransferases obtained by random substitution and genetic selection in bacteria; Christians FC et al.; DNA repair alkyltransferases protect organisms against the cytotoxic, mutagenic, and carcinogenic effects of alkylating agents by transferring alkyl adducts from DNA to an active cysteine on the protein, thereby restoring the native DNA structure . We used random sequence substitutions to gain structure-function information about the human O6-methylguanine-DNA methyltransferase (EC 2.1.1.63), as well as to create active mutants . Twelve codons surrounding but not including the active cysteine were replaced by a random nucleotide sequence, and the resulting random library was selected for the ability to provide alkyltransferase-deficient Escherichia coli with resistance to the methylating agent N-methyl-N'-nitro-N-nitrosoguanidine . Few amino acid changes were tolerated in this evolutionarily conserved region of the protein . One mutation, a valine to phenylalanine change at codon 139 (V139F), was found in 70% of the selected mutants; in fact, this mutant was selected much more frequently than the wild type . V139F provided alkyltransferase-deficient bacteria with greater protection than the wild-type protein against both the cytotoxic and mutagenic effects of N-methyl-N'-nitro-N-nitrosoguanidine, increasing the D37 over 4-fold and reducing the mutagenesis rate 2.7-5.5-fold . This mutant human alkyltransferase, or others similarly created and selected, could be used to protect bone marrow cells from the cytotoxic side effects of alkylation-based chemotherapeutic regimens.

Virus Res, 1996 Jun, 42(1-2), 81 - 96
The E6 variant proteins E6I-E6IV of human papillomavirus 16: expression in cell free systems and bacteria and study of their interaction with p53; Shally M et al.; Several species of alternatively spliced mRNAs are transcribed from the E6 gene region of human papillomavirus (HPV) 16 . These have the coding capacity for either the full length E6 of 151 amino acids (aa) or four truncated variants, E6I-E6IV, of 43-64 aa . As the first step to identify the putative E6 variants and their functions, we generated cDNAs corresponding to the various E6 open reading frames (ORF) and examined their expression employing in vitro transcription/translation systems and the bacterial pET system . In wheat germ extract, in vitro translation resulted in the production of all five proteins, E6 and E6I-E6IV . These proteins were also expressed as stable fusion proteins from the pET16b and pET17 x b vectors in Escherichia coli . Mobilites of the E6 variant proteins on SDS-acrylamide gels were consistent with their predicted sizes . The authenticity of the synthesized proteins was confirmed by immunoprecipitation with specific antibodies directed against epitopes in the N-terminal portion of E6 as well as antibodies raised against the individual variant proteins produced in E . coli . In rabbit reticulocyte lysate, however, only the full length E6 and the E6IV variant were synthesized . This could be due to inefficient translation as well as lower stability of the short variants . E6I-III, in reticulocyte lysate (RTL) . The ability of the E6 variants to associate with p53 and target its proteolytic degradation in vitro, was examined in coimmunoprecipitation assays, using in vitro synthesized proteins and monoclonal antibodies to p53 . Results of these assays indicated that only the full length E6 efficiently binds to and promotes the degradation of p53 . The E6 variants E6I-E6IV, although able to associate with p53 at a low efficiency, were unable to target its degradation.

Appl Environ Microbiol, 1996 Jun, 62(6), 2163 - 8
Population dynamics of propionate-oxidizing bacteria under methanogenic and sulfidogenic conditions in anaerobic granular sludge; Harmsen HJ et al.; Laboratory-scale upflow anaerobic sludge-bed reactors were inoculated with industrial granular sludge and fed with either propionate or propionate and sulfate . The population dynamics of the propionate-oxidizing bacteria Desulfobulbus sp . and the syntrophically growing strain SYN7 were studied in reactors by dot blot and in situ hybridization with 16S rRNA-based oligonucleotide probes.

Curr Opin Biotechnol, 1996 Jun, 7(3), 287 - 94
Environmental processes mediated by iron-reducing bacteria; Fredrickson JK et al.; Considerable progress has been made towards enhancing our understanding of the phylogeny, ecology and biogeochemical role of dissimilatory iron-reducing bacteria . The known phylogenetic range of iron-reducing bacteria has expanded considerably, as has the known range of iron minerals that serve as a source of Fe(III) for anaerobic respiration . In addition, the number of biotechnological applications of iron-reducing bacteria, including remediation of soils and sediments contaminated with metals, radionuclides and organics, is rapidly expanding.

Genetics, 1996 Jun, 143(2), 637 - 44
Genetic divergence and fitness convergence under uniform selection in experimental populations of bacteria; Korona R; Replicate populations of bacteria were propagated for 1000 generations in the laboratory . The growth substrate was periodically renewed, so that during most generations (cell doublings) it was not limiting . The final clones demonstrated about a 40% fitness increase when competed against their common ancestor . This increase was uniform both among and within populations despite extensive differentiation in correlated traits: cell size, resistance to starvation and dry mass of culture . It is suggested that genetic diversity developed because selection promoted any changes directing cell activity toward a higher maximum growth rate . Evolution of this trait halted at a similar level when some basic constraints on bacterial metabolism were met . The selective values of emerging mutations must have depended on the genetic background . They would be beneficial early in evolution but ineffective near the limit of adaptation . This hypothesis was tested for one mutation that affected both fitness and colony morphology . In some clones it was the first adaptive mutation and provided a third of the total fitness increase, but it was not assimilated by the clones that reached the adaptive ceiling in some other way . Near the limit of adaptation, epistasis levels off the fitnesses of genetically variable clones.

J Appl Bacteriol, 1996 Jun, 80(6), 673 - 81
Rapid physicochemical detachment, separation and concentration of bacteria from beef surfaces; Rodrigues-Szulc UM et al.; A simple, rapid, physicochemical treatment for the removal of viable bacteria from the surface of raw and cooked beef is described . The detachment method was linked to a differential centrifugation step which removed large amounts of particulate food matter and concentrated the detached bacteria . The method increased the numbers of bacteria released from beef surfaces and increased the numbers detected by at least one and a half orders of magnitude, when compared to the traditional 'stomaching' technique . This 1-h separation and concentration method produced cleaner suspensions of bacteria and improved the sensitivity of detection by DEFT and direct plate count.

Biosci Biotechnol Biochem, 1996 Jun, 60(6), 935 - 41
The monoamine regulon including syntheses of arylsulfatase and monoamine oxidase in bacteria; Murooka Y et al.; Bacterial cells respond to monoamine compounds, such as tyramine, dopamine, octopamine, or norepinephrine, and induce the syntheses of tyramine oxidase encoded by tynA and monoamine oxidase encoded by maoA . These monoamine compounds also derepress the synthesis of atsA-specified arylsulfatase that is repressed by sulfur compounds . These complex mechanisms of regulons regulated by monoamine and sulfur compounds has been analyzed by cloning and characterization of genes that are involved in the repression and derepression of the synthesis of arylsulfatase . The atsA gene forms an operon with the atsB gene, which encodes an activator of the expression of atsA . The negative regulator gene for arylsulfatase was found to code for dihydrofolate reductase (folA) . The maoA gene forms an operon with the maoC gene, which has similarity to a dehydrogenase involved in the tyramine metabolism . The moaF gene encoding a 30-kDa protein, which is induced by tyramine, also forms an operon with the moaE gene . Finally, the moaR gene, which is induced by monoamine, was found to play a central role in the positive regulation of the expression of the monoamine regulon (moa) including the atsBA, maoCA, moaEF, and tyn operons . The moaR expression is subject to autogenous regulation and to cAMP-CRP control . The MoaR protein has a helix-turn-helix motif in its C terminus . Thus, the MoaR protein probably regulates the operons by binding to the regulatory region of the moa regulon.

FEBS Lett, 1996 May 27, 387(1), 81 - 4
Exciton delocalization in the antenna of purple bacteria: exciton spectrum calculations using Z-ray data and experimental site inhomogeneity; Dracheva TV et al.; Electron absorption and circular dichroism spectra of the peripheral light-harvesting complex (LH2) of photosynthetic purple bacteria were calculated taking into account the real-life spatial arrangement and experimental inhomogeneous broadening of bacteriochlorophyll molecules . It was shown that strong excitonic interactions between 18 bacteriochlorophyll molecules (BCh1850) within the circular aggregate of the LH2 complex result in an exciton delocalization over all these pigment molecules . The site inhomogeneity (spectral disorder) practically has no influence on exciton delocalization . The splitting between two lowest exciton levels corresponds to experimentally revealed splitting by hole-burning studies of the LH2 complex.

Science, 1996 May 24, 272(5265), 1153 - 5
Bacteria as Mediators of Copper Sulfide Enrichment During Weathering
Sillitoe RH, Folk RL, Saric N.
Supergene chalcocite enrichment during weathering is an economically vital natural process that may lead to severalfold increases in the copper content of sulfide deposits . A scanning electron microscope study of chalcocite (Cu2S) from major enriched copper deposits in northern Chile revealed myriad bacterioform bodies in original growth positions near replacement interfaces with remnant hypogene sulfide grains . These minute (0.03 to 0.2 micrometers) chalcocite bodies are interpreted as fossilized and metallized nannobacteria that promoted the fixation of mobilized copper ions . Bacterial activity may thus be a fundamental factor in supergene enrichment of copper deposits.

Biofizika, 1996 May-Jun, 41(3), 636 - 41
{Effect of aggregate state, tonicity, and level of nutrients in media on recovery of Escherichia coli bacteria from heat damage}; Morozov II; The influence of aggregate condition, nutrient composition and tonicity of incubation medium on recovery from damages induced by heat at 52 degrees C Escherichia coli B/r and Escherichia coli BS-1 cells was studied . The cells were shown to be recovered from heat damages only in liquid and isotonic medium . The observed increase in a number of viable organisms was not greatly depended on source of energy, plastic material and macroelements of incubation medium . The recovered cells showed increase of osmotic tolerance to hyper- and hypotonic shock similar to intact cells . No increase in survivors was observed when heated cells were incubated on solid and/or anisotonic medium . The additional cell killing and high osmosensitivity may be seen in this case . The role of the system of osmotic homeostasis, including membrane state, in the modification of cell viability and osmoresistance of heated bacterial cells was discussed on the base of the data obtained.

Antonie Van Leeuwenhoek, 1996 May, 69(4), 293 - 303
Genome size in bacteria; Trevors JT; This manuscript examines genome size in bacteria . The opposing capability of bacteria to alter their genome sizes and order of genes within limits yet remain somewhat constant provides a mechanisms for diversity and evolution in bacterial populations . Bacteria may have evolved by increasing their genome size and changing gene orders with the assistance of restriction endonucleases cleaving foreign DNA and providing a diverse pool of DNA sequences for recombination . These aspects and selected information on physically mapping bacterial genomes will be discussed.

Ultrastruct Pathol, 1996 May-Jun, 20(3), 203 - 9
Bacteria in biopsies of human hypochlorhydric stomach: a scanning electron microscopy study; Brandi G et al.; A long-lasting condition of hypochloridria leads to a bacterial growth both in the gastric lumen and biopsies of human stomach . Some of these bacteria are probably involved in gastric carcinogenesis, due to their capacity of nitrosation . This study was carried out on biopsies taken during endoscopy from both gastric antrum and the body of patients with or without hypochloridria . Scanning electron microscopy observation shows that bacteria, other than Helicobacter pylori, found in hypochloridria, can be located not only over but also into and under the mucus layer covering the gastric epithelium . In such areas, mechanical and biochemical damage may occur.

J Bacteriol, 1996 May, 178(9), 2709 - 11
Elevated mutation rate in mutT bacteria during starvation: evidence for DNA turnover?
Bridges BA.
The rate of appearance of prototrophic revertants when Escherichia coli tyrA14 (ochre) or trpA23 bacteria were incubated on plates lacking the required amino acid was greatly elevated when the organisms also carried a mutT mutation . One possible explanation for this result is that the amount of DNA replication or turnover under these conditions is much greater than has been previously recognized.

Proc Natl Acad Sci U S A, 1996 Apr 2, 93(7), 2879 - 83
CpG motifs present in bacteria DNA rapidly induce lymphocytes to secrete interleukin 6, interleukin 12, and interferon gamma; Klinman DM et al.; Bacterial infection stimulates the host to mount a rapid inflammatory response . A 6-base DNA motif consisting of an unmethylated CpG dinucleotide flanked by two 5' purines and two 3' pyrimidines was shown to contribute to this response by inducing polygonal B-cell activation . This stimulatory motif is 20 times more common in the DNA of bacteria than higher vertebrates . The current work shows that the same motif induces the rapid and coordinated secretion of interleukin (IL) 6, IL-12, and interferon gamma (but not IL-2, IL-3, IL-4, IL-5, or IL-10) in vivo and in vitro . Stimulatory CpG DNA motifs induced B, T, and natural killer cells to secrete cytokine more effectively than did lipopolysaccharide . Thus, immune recognition of bacterial DNA may contribute to the cytokine, as well as the antibody production characteristic of an innate inflammatory response.

Proc Natl Acad Sci U S A, 1996 Apr 2, 93(7), 2873 - 8
Accelerated evolution and Muller's rachet in endosymbiotic bacteria; Moran NA; Many bacteria live only within animal cells and infect hosts through cytoplasmic inheritance . These endosymbiotic lineages show distinctive population structure, with small population size and effectively no recombination . As a result, endosymbionts are expected to accumulate mildly deleterious mutations . If these constitute a substantial proportion of new mutations, endosymbionts will show (i) faster sequence evolution and (ii) a possible shift in base composition reflecting mutational bias . Analyses of 16S rDNA of five independently derived endosymbiont clades show, in every case, faster evolution in endosymbionts than in free-living relatives . For aphid endosymbionts (genus Buchnera), coding genes exhibit accelerated evolution and unusually low ratios of synonymous to nonsynonymous substitutions compared to ratios for the same genes for enterics . This concentration of the rate increase in nonsynonymous substitutions is expected under the hypothesis of increased fixation of deleterious mutations . Polypeptides for all Buchnera genes analyzed have accumulated amino acids with codon families rich in A+T, supporting the hypothesis that substitutions are deleterious in terms of polypeptide function . These observations are best explained as the result of Muller's ratchet within small asexual populations, combined with mutational bias . In light of this explanation, two observations reported earlier for Buchnera, the apparent loss of a repair gene and the overproduction of a chaperonin, may reflect compensatory evolution . An alternative hypothesis, involving selection on genomic base composition, is contradicted by the observation that the speedup is concentrated at nonsynonymous sites.

AANA J, 1996 Apr, 64(2), 153 - 6
An evaluation of one and two airflow filters in preventing the movement of bacteria through the anesthesia circle system; Smith C et al.; A review of the literature demonstrated that controversy exists as to whether anesthesia circle systems can be a source of transmission of bacteria to patients . The purpose of this study was to evaluate the use of one airflow filter (on the expiratory limb) versus two airflow filters (one on the inspiratory limb and one on the expiratory limb) in the prevention of bacterial migration in the anesthesia circle system, during general anesthesia, using semiquantitative analysis of the number of bacterial colony forming units (CFUs) . This study consisted of two randomized groups receiving one or two airflow filters . Thirty-five volunteers participated in the study . At the conclusion of the surgical cases, a culture was taken of the anesthesia circle system . The cultures were read at 24 and 48 hours for the presence of CFUs . No CFUs were reported in either group . The results of the study were inconclusive . Therefore, the use of one airflow filter on the expiratory limb should remain the standard of care, pending additional research . Some practitioners may use a second airflow filter when there is a greater risk of infection, such as in the case of an immunocompromised patient . However, this study can neither support nor question the effectiveness of this practice.

Arch Microbiol, 1996 Apr, 165(4), 219 - 25
Control of nitrogen fixation by oxygen in purple nonsulfur bacteria
Oelze J, Klein G.
Some members of the facultatively phototrophic bacteria are able to grow diazotrophically in the presence of oxygen . As in other diazotrophs, the nitrogenase of the phototrophic bacteria is highly sensitive to oxygen; therefore, both the function and the expression of nitrogenase are strictly controlled by oxygen . This review focuses on the different levels of oxygen control in the two most extensively studied facultatively phototrophic bacteria, Rhodospirillum rubrum and Rhodobacter capsulatus . Current data show that oxygen controls nitrogen fixation at least at the levels of (1) transcription of nif genes, (2) the accumulation of the three different nitrogenase polypeptides, (3) the cellular activity of nitrogen fixation . In Rba . capsulatus, activation of the nifH promoter is the least oxygen-sensitive step, and nitrogen fixation is the most oxygen-sensitive step . ADP-Ribosylation of nitrogenase, occurring under conditions of ammonium-dependent inactivation of the enzyme, is not observed when Rba . capsulatus is exposed either suddenly or at a steady state to increased oxygen concentrations . Future research is required to understand the mechanisms of protection of nitrogenase against oxygen damage, and also the mechanisms by which oxygen controls the formation and activity of nitrogenase; this will add significantly to the biologically important question of how cells deal with the presence of toxic oxygen.

Trends Genet, 1996 Apr, 12(4), 150 - 5
Who's competent and when: regulation of natural genetic competence in bacteria; Solomon JM et al.; Natural genetic competence, the ability of cells to bind to and to take up exogenous DNA, is widespread among bacteria and might be an important mechanism for the horizontal transfer of genes . Competent cells express specialized proteins that assemble into a DNA-uptake complex . In many organisms, the development of competence and expression of the uptake machinery is regulated in response to cell-cell signaling and/or nutritional conditions . Exciting new progress has been made in characterizing the signals and pathways that regulate the development of competence.

Biotechniques, 1996 Apr, 20(4), 684 - 93
pGATA: a positive selection vector based on the toxicity of the transcription factor GATA-1 to bacteria; Trudel P et al.; The transcription factor GATA-1 is a zinc finger DNA-binding protein essential for the development of red blood cells . When we expressed different regions of the zinc finger domain in bacteria using an isopropyl-beta-D-thiogalactoside (IPTG) inducible system, growth of bacteria harboring the active DNA-binding domain of GATA-1 was rapidly inhibited upon IPTG induction . The growth inhibition pattern suggested it may be occurring at the level of the initiation of replication, and GATA-1 was found to bind to three of the four DNA A protein-binding sites in the origin of replication . This toxicity was used to develop a positive selection vector system in which cloned DNA fragments interfered with the production of the GATA-1 DNA-binding domain . Thus, vector molecules containing the insert of interest are selected for when bacteria are grown in the presence of IPTG . With this system, the vector does not need to be dephosphorylated, purified or completely digested with a restriction enzyme for the efficient cloning of DNA fragments even when the vector-to-insert DNA molar ratio in ligation reactions is 10 to 1 . Moreover, no special strain of Escherichia coli is required, and the selection might also be applicable to other species of bacteria if the toxicity of GATA-1 relates to inhibition of the DNA A protein.

Thorax, 1996 Apr, 51(4), 378 - 84
Value of intracellular bacteria detection in the diagnosis of ventilator associated pneumonia; Torres A et al.; BACKGROUND: Markers of ventilator associated pneumonia are of interest for confirming the diagnosis and for guiding the initial management of this frequent complication of mechanical ventilation . The detection of intracellular organisms in the polymorphonuclear leucocytes (PMNLs) and/or macrophages of bronchoalveolar lavage (BAL) fluid has been suggested as a specific test for the early indication of an infectious pulmonary process . METHODS: The diagnostic value of detecting intracellular organisms in two types of BAL fluid--protected (P-BAL) and conventional (C-BAL)--in 25 patients who died in one unit was prospectively studied . Immediately after death both P-BAL and C-BAL were performed bilaterally . Through a minithoracotomy on both sides of the chest bilateral bronchoscopically guided open lung biopsy samples were obtained from the same area, and an average of eight open lung blind biopsy samples (not bronchoscopically guided) were taken from each lung for histological examination . BAL fluid was examined for quantitative cultures (threshold 10(4) cfu/ml) and for the presence of intracellular organisms and extracellular organisms, and differential cell counts were also performed . RESULTS: Using the histopathology of the bronchoscopically guided open lung biopsies as the gold standard, detection of intracellular organisms in P-BAL (> or = 5%) and C-BAL (> or = 5%) fluids yielded 75% and 57% positive predictive values, and 83% negative predictive values, respectively . Prior treatment with antibiotics decreased the positive and negative predictive values of intracellular organism detection for both types of BAL fluid . The presence of intracellular organisms was correlated with the quantitative cultures of P-BAL and C-BAL samples . Quantitative cultures from P-BAL fluid were less sensitive (22% versus 45%) and more specific (100% versus 55%) than those from C-BAL samples . The percentage of extracellular organisms and the differential cell count in P-BAL and C-BAL samples could not discriminate between the presence or absence of pneumonia . CONCLUSIONS: The presence of > or = 5% intracellular organisms infecting PMNLs or macrophages in P-BAL or C-BAL fluids is a specific marker of ventilator associated pneumonia.

J Laryngol Otol, 1996 Apr, 110(4), 339 - 42
Immunoglobulin-coated bacteria on the tonsillar surface during infectious mononucleosis; Stenfors LE et al.; Sequential bacterial samples were obtained from the tonsillar surface of 19 consecutive patients (12 females, seven males; mean age 16.1 years, range four to 24 years) suffering from infectious mononucleosis with membranous tonsillitis . The specimens were examined with respect to aerobes (culture on blood and chocolate agar plates) and proportions of bacteria coated with immunoglobulins (secretory IgA, IgG, IgM) by using an immunofluorescence assay . In the early stage of the membranous tonsillitis phase, attachment of secretory IgA (SIgA) and IgG to the bacteria was greatly suppressed, as compared with healthy controls . Coating with IgM was evident only late in the membranous tonsillitis phase but was contracted and still evident even after the clinical throat symptoms had abated . The findings suggest that the B-lymphotropic Epstein-Barr virus, causative agent of infectious mononucleosis, exerts a transient suppression of immunoglobulin-coating of bacteria harboured on the tonsillar surfaces, with consequent abundant bacterial attachment to the epithelial cells and massive bacterial colonization on the palatine tonsils.

Zentralbl Veterinarmed A, 1996 Apr, 43(2), 111 - 7
Characterization of camel leukocytes by flow cytometry and microscopic evaluation of granulocyte phagocytosis of fluorescent bacteria; Abdurahman OA et al.; Peripheral blood was obtained from four lactating camels (Camelus bactrianus) and flow cytometry was used to characterize cell populations . The ability of the granulocytes to engulf fluorescent bacteria was studied in vitro using fluorescence microscopy . Three clusters of blood cells (mononuclear cells, neutrophils and eosinophils) were identified by flow cytometry and fluorescent microscopy . Milk, on the other hand, was dominated by cell fragments and no distinct cluster formation was found . The mean yield of blood granulocytes and monocytes isolated on Ficoll gradient was 92.2 +/- 5.4% and 7.9 +/- 5.7%, respectively . Cell viability was 95% . The mean percentage of phagocytic cells was 71.8 +/- 5.9% at 10 min and increased to 97.3 +/- 0.5% at 60 min when observation was terminated . The average number of bacteria per phagocyte was 8.7 +/- 2.1 and 13.1 +/- 0.9 at 10 and 60 min incubation time.

Appl Environ Microbiol, 1996 Mar, 62(3), 1084 - 8
Utilization of individual cellodextrins by three predominant ruminal cellulolytic bacteria; Shi Y et al.; Growth of the ruminal bacteria Fibrobacter succinogenes S85, Ruminococcus flavefaciens FD-1, and R . albus 7 followed Monod kinetics with respect to concentrations of individual pure cellodextrins (cellobiose, cellotriose, cellotetraose, cellopentaose, and cellohexaose) . Under the conditions tested, R . flavefaciens FD-1 possesses the greatest capacity to compete for low concentrations of these cellodextrins.

Can J Microbiol, 1996 Mar, 42(3), 259 - 66
Characterization of sulfate-reducing bacteria isolated from oil-field waters; Tardy-Jacquenod C et al.; The occurrence and metabolic capacities of sulfate-reducing bacteria (SRB) were studied in 23 water samples taken from producing wells at 14 different sites . Oil fields in France, the North Sea, and the Gulf of Guinea were selected and classified according to physicochemical parameters (salinity ranging from 0.3 to 120 g.L-1 and temperature between 29 and 85 degrees C) . After the distribution of SRB within oil fields was studied, several strains of SRB were isolated and characterized metabolically . Twenty of the thirty-seven strains were not related to any known species . Most of the identified strains were members of the genera Desulfovibrio and Desulfotomaculum by molecular, morphological, and physiological properties.

Chemosphere, 1996 Mar, 32(5), 921 - 33
A growth inhibition test with sewage bacteria--results of an international ring test 1995; Strotmann UJ et al.; A bacterial toxicity test method using the determination of growth inhibition of sewage bacteria within an incubation period of 6 hours will be standardized at ISO . A ring test was performed with 24 participants using 3.5-dichlorophenol and potassium cyanide as test substances . The analysis of the test results showed that the method is very accurate and appropriate for determining the bacterial toxicity of chemical compounds . Due to the results obtained 3.5-dichlorophenol was proposed as a reference substance.

Zentralbl Bakteriol, 1996 Mar, 283(3), 346 - 50
Phagocytosis of Helicobacter pylori bacteria differing in the heparan sulfate binding by human polymorphonuclear leukocytes; Chmiela M et al.; Heparan sulfate binding proteins (HSBPs) of Helicobacter pylori facilitate bacterial phagocytosis by human polymorphonuclear leukocytes (PMNs) . H . pylori 25 strain which demonstrates a strong heparan sulfate binding activity was found to be attached to/ingested by PMNs in greater numbers than H . pylori strain 17874 bacteria which lacked this activity . Moreover, heparin inhibited the uptake of cells of H . pylori strain 25 but not of cells of H . pylori strain 17874 by PMNs.

FEMS Immunol Med Microbiol, 1996 Mar, 13(3), 221 - 5
Orchestration of the protective immune response to intracellular bacteria: Francisella tularensis as a model organism; Tarnvik A et al.; Francisella tularensis is used as a model organism in studies of mechanisms behind the induction of a protective T-cell response in the mammalian host . Protective immunity is associated with a CD4 and CD8 T-cell response towards a mosaic of proteins of F . tularensis and due to HLA restriction, each individual selects her own mosaic . No single protein has so far been shown to be immunodominant . Only live F . tularensis affords effective host protection . Subcellular antigen preparations induce only a marginal protective response even when combined with potent adjuvants such as immunostimulating complexes (ISCOMs) . In mice, intradermal injection of live F . tularensis but not of killed bacteria results in an early cytokine expression in the infected liver, including interleukin-12, tumor necrosis factor-alpha, and interferon-gamma . This cytokine response seems to be a prerequisite for effective priming of T cells to an array of proteins of F . tularensis to occur.

Phytochemistry, 1996 Mar, 41(4), 1047 - 55
Purification of (+)-delta-cadinene synthase, a sesquiterpene cyclase from bacteria-inoculated cotton foliar tissue; Davis EM et al.; A sesquiterpene cyclase whose activity is induced in a glandless, bacterial blight-resistant line of cotton (Gossypium hirsutum L.) catalyses the conversion of (E,E)-farnesyl diphosphate to (+)-delta-cadinene . This enzyme was purified by a combination of salt-induced phase separation, hydroxylapatite fractionation, hydrophobic interaction and strong anion-exchange chromatography, and denaturing polyacrylamide gel electrophoresis, followed by renaturation with Tween 80 . The purified enzyme has a molecular weight of 64-65 kDa, and exhibited a single silver-staining band following electrophoresis in analytical denaturing polyacrylamide gels . Amino acid sequences of three tryptic peptides from the enzyme have been determined and are similar to known sequences in other terpene cyclases from plants.

J Bacteriol, 1996 Mar, 178(5), 1451 - 6
Phylogenetic analysis of Metabacterium polyspora: clues to the evolutionary origin of daughter cell production in Epulopiscium species, the largest bacteria; Angert ER et al.; It is rare that there are molecular clues to the evolutionary origin of developmental traits . We have encountered an evolutionary juxtaposition that may explain the origin of the unique replicative morphology of Epulopiscium spp., the largest known bacteria, which reproduce by the internal production of multiple live offspring . We report here a 16S rRNA-based phylogenetic analysis of Metabacterium polyspora, a multiple-endospore-forming, uncultivated inhabitant of guinea pig cecum . Cells of M . polyspora were harvested from cecum contents by sedimentation in a Ficoll gradient and lysed . The bacterial 16S rRNA genes of this lysate were amplified by PCR . Sequence analysis of the cloned PCR products revealed two dominant, closely related 16S rRNA types . In situ hybridization of cecum contents with fluorescently labeled oligonucleotides, diagnostic of these two sequences, showed that they represent distinct strains of M . polyspora . Phylogenetic analyses of the sequences showed that M . polyspora is closely related to Epulopiscium spp . On the basis of this result and other correlations, we propose that the process of sporulation was modified in a predecessor of Epulopiscium spp . to produce live offspring instead of quiescent endospores.

J Chromatogr B Biomed Appl, 1996 Feb 23, 677(1), 53 - 9
Measurement of total and separate stereoisomers of diaminopimelic acid in rumen bacteria by high-performance liquid chromatography; el-Waziry AM et al.; New high-performance liquid chromatographies were examined and applied for the analyses of the total (with one peak) and separate three stereoisomers of 2,6-diaminopimelic acid (DAP) in hydrolysed mixed rumen bacteria . The methods start with the reaction of DAP with 1-fluoro-2,4-dinitrophenylalanine amide for derivatisation . A mixture of 0.05 M triethylamine phosphate (pH 3.0) and acetonitrile (72:28, v/v) was used as an isocratic mobile phase for the total DAP determination (method 1), and a mixture of both solutions (78.5:21.5, v/v) for the determination of the separate three stereoisomers of DAP (method 2) . The flow-rate was 1 ml/min; column, Merck LiChrospher 100 RP-18 (250 x 4 mm I.D.) of 5 microns particle size; column temperature, 40 degrees C; wavelength of detector, 325 nm . The retention times were 17.5 min for total DAP (method 1), and 39.4, 63.1 and 77.7 for meso-, LL- and DD-DAP, respectively (method 2) . Lysine can also be determined by method 2 and the retention time was 122.8 min . The minimum detectable limit was 2.5 microM . The average analytical recoveries were 98.6% for total DAP and 99.1%, 100.4% and 100.2% for meso-, LL- and DD-DAP, respectively . The content of total DAP of the hydrolysed rumen bacteria collected from three goats fed lucerne cube and concentrate ranged from 25.55 to 27.36 mumol/g bacterial DM (method 1) . The contents of the separate stereoisomers of DAP in the hydrolysed rumen bacteria from the three goats ranged from 19.64 to 22.06 and from 4.98 to 5.21 mumol/g bacterial DM for meso- and LL-DAP, respectively (method 2) . DD-DAP was not detected.

J Biol Chem, 1996 Feb 16, 271(7), 3608 - 14
Biosynthesis of inner core lipopolysaccharide in enteric bacteria identification and characterization of a conserved phosphoheptose isomerase; Brooke JS et al.; The lpcA locus has been identified in Escherichia coli K12 novobiocin-supersensitive mutants that produce a short lipopolysaccharide (LPS) core which lacks glyceromannoheptose and terminal hexoses . We have characterized lpcA as a single gene mapping around 5.3 min (246 kilobases) on the E . coli K12 chromosome and encoding a 22.6-kDa cytosolic protein . Recombinant plasmids containing only lpcA restored a complete core LPS in the E . coli strain chi711 . We show that this strain has an IS5-mediated chromosomal deletion of 35 kilobases that eliminates lpcA . The LpcA protein showed discrete similarities with a family of aldose/ketose isomerases and other proteins of unknown function . The isomerization of sedoheptulose 7-phosphate, into a phosphosugar presumed to be D-glycero-D-mannoheptose 7-phosphate, was detected in enzyme reactions with cell extracts of E . coli lpcA+ and of lpcA mutants containing the recombinant lpcA gene . We concluded that LpcA is the phosphoheptose isomerase used in the first step of glyceromannoheptose synthesis . We also demonstrated that lpcA is conserved among enteric bacteria, all of which contain glyceromannoheptose in the inner core LPS, indicating that LpcA is an essential component in a conserved biosynthetic pathway of inner core LPS.

Gene, 1996 Feb 2, 168(1), 73 - 5
FliH and fliI of Borrelia burgdorferi are similar to flagellar and virulence factor export proteins of other bacteria; Ge Y et al.; Two motility genes (fliH and fliI) of the Lyme disease spirochete Borrelia burgdorferi were cloned, physically mapped and sequenced, FliH and FliI showed extensive homology to the proteins involved in the export of flagellar components and to virulence factors found in both animal and plant bacterial pathogens . The results suggest that the flagellar apparatus and associated protein export pathway are well conserved in evolution.

FEMS Microbiol Lett, 1996 Feb 1, 136(1), 1 - 11
Nitrate reduction to ammonia by enteric bacteria: redundancy, or a strategy for survival during oxygen starvation?
Cole J.
Anaerobic metabolism of the simplest, best understood enteric bacteria such as Escherichia coli is unexpectedly complex . Recent studies of the biochemistry and genetics of nitrate reduction via nitrite to ammonia by enteric bacteria have provided insights into the reasons for this complexity . An NADH-dependent nitrite reductase in the cytoplasm works in partnership with the respiratory nitrate reductase on the cytoplasmic side of the membrane when nitrate is abundant . There is also an electrogenic, formate-dependent nitrite reductase ready to work in partnership with a periplasmic nitrate reductase when nitrite is available but nitrate is scarce . A third E . coli nitrate reductase, NarZYWV, and the poorly expressed formate dehydrogenase O possibly facilitate rapid adaptation to oxygen starvation pending the synthesis of the major respiratory formate-nitrate oxidoreductase . Although most anaerobically expressed genes are subject to transcription control, none of them are totally switched off . This enables the bacteria to be ready for a change in fortune: when growing anaerobically with nitrate, they can respond equally rapidly whether times get better with the arrival of oxygen, or get worse when the nitrate is depleted . Far from being redundant, the complexity is essential for survival in a changing environment.

Trends Microbiol, 1996 Feb, 4(2), 69 - 72
Genetic barriers among bacteria; Matic I et al.; Barriers to chromosomal gene transfer between bacterial species control their genetic isolation . These barriers, such as different microhabitats, the host ranges of genetic exchange vectors and restriction-modification systems, limit gene exchange, but the major limitation is genomic sequence divergence . The mismatch-repair system inhibits interspecies recombination, the inducible SOS system stimulates interspecies recombination, while natural selection determines the effective recombination frequencies.

Mutat Res, 1996 Jan 17, 349(1), 51 - 61
Peroxynitrite-induced mutation spectra of pSP189 following replication in bacteria and in human cells; Juedes MJ et al.; Peroxynitrite is a powerful oxidant formed through reaction of nitric oxide with superoxide . Because activated macrophages can produce both nitric oxide and superoxide, it has been proposed that peroxynitrite may contribute to cytotoxicity and increased cancer risks associated with the inflammatory response during chronic infections . We therefore investigated mutagenicity of peroxynitrite in the supF gene of the pSP189 shuttle vector as a mutation target . The plasmid was exposed to 2.5 mM peroxynitrite in vitro, then replicated in Eschericia coli MBL50 and in human AD293 cells . Mutation frequency increased 21-fold in pSP189 replicated in E . coli and 9-fold in plasmid replicated in human cells . Mutations were clustered within the 5' region of the supF gene in plasmids replicated in bacteria . The hot spots were located at positions 108, 113, 116, 124, 126 and 141; more than 25% of all mutations occurred at position 124 . Following replication in human cells, mutations were more widely distributed over the gene, with hot spots at positions 113, 124, 133, 156 and 164; 15% occurred at position 124 . In both systems, the majority of mutations occurred at G:C base pairs, predominantly involving G:C-->T:A transversions (65% when replication was in bacteria and 63% when in human cells) . G:C-->C:G transversions were observed at lower frequency (28% in MBL50 and 11% in AD293 cells), and 11% of mutations found in vectors replicated in AD293 cells were G:C-->A:T transitions . A greater number of large deletions, insertions, tandem and multiple mutations occurred in plasmid replicated in AD293 cells . Differences in mutation spectra following replication in the two systems may be attributable to differences in recognition and repair of the lesions and/or properties of the replication apparatus.

Tsitologiia, 1996, 38(12), 1269 - 73
{The dependence of the osmotic properties of Escherichia coli bacteria on temperature}; Morozov II et al.; The influence of water solutions of NaCl on the osmoresistance and reproduction of E . coli B/r and E . coli Bs-1 at different temperatures was studied . The increase in cell resistance was studied . The increase in cell resistance to NaCl hypertonia was noticed after the temperature rise from 20 to 37 degrees C . In this case the concentration of NaCl in the medium, which made this medium isotonic, was seen to increase too . On the contrary, when the temperature decreased to 0 degrees, the cell resistance to high concentrations of NaCl was found suppressed . In this case the concentration of NaCl in the medium, which made this medium isotonic, was seen to decrease . The salt tolerance of bacteria reproduction was found to depend on the temperature: the tolerance increased with the temperature rise, and vice versa . It is concluded that the solution temperature was to be considered as one of the major factors governing the osmotic bacterial cell homeostasis.

Bull Inst Marit Trop Med Gdynia, 1996, 47(1-4), 93 - 103
The sea to air bacteria transfer from the coastal waters; Marks R et al.; Bacteria transfer from the water into the air may play an important role in bioaerosol cycle . Bubbles raising through the water column collect bacteria but also other suspended material and transport them towards water surface . When the bubble burst at the water surface collected material are skimmed off the bubble to become highly enriched in jet and film drops . After ejection airborne droplets can evaporate and as small droplets can be transported even to remote locations . Such a stream of aerosol droplets may carry stream of bacteria scavenged from the water column . The fate of bacteria in the air may possibly depend on the environmental conditions like intensity of sunlight or ambient air humidity . In addition the wind speed might be responsible for both wave/bubble mediated production of marine originated droplets and their transport in the atmosphere . The evidences that bacteria are transferred from the breaking waves, in particular in the coastal zone, were observed during several field experiments conducted in 1994 and 1995 over the Gulf of Gdansk and the Baltic Sea coast . Enhanced sea to air bacteria transfer were noticed over the polluted waters where in addition gas supersaturations in the water were recorded . Further laboratory investigations of bacteria scavenge via bubbles produced by single capillary and by plume of bubbles produced by ceramic stone indicated high enrichment within both mesophile and psychrophile bacteria categories.

Biol Cell, 1996, 87(1-2), 1 - 8
Towards an understanding of the structural and functional properties of MscL, a mechanosensitive channel in bacteria; Blount P et al.; Whether it be to sense a touch, arterial pressure, or an osmotic gradient across a cell membrane, essentially all living organisms require the capability of detecting mechanical force . Electrophysiological evidence has suggested that mechanosensitive ion channels play a major role in many systems where mechanical force is detected . But, despite their biological importance, determination of the most basic structural and functional features of mechanosensitive channels has only recently become possible . A gene called mscL, which was isolated from Escherichia coli, was the first gene shown to encode a mechanosensitive channel activity . This channel directly responds to tension in the membrane; no other proteins are required . MscL appears to be a homohexamer of a 136 amino acid polypeptide that is highly alpha helical, contains two transmembrane domains, and has both the amino and carboxyl termini in the cytoplasm . The study of the MscL protein remains, to date, one of the most viable options for understanding the structural and functional characteristics of a mechanosensitive channel.

Environ Mol Mutagen, 1996, 28(4), 397 - 404
Database and software for the analysis of mutations at the lacI gene in both transgenic rodents and bacteria; Cariello NF et al.; The use of transgenic rodents for the study of genetic toxicology has increased dramatically in the past several years . A great deal of the recent work has employed the lacI locus in transgenic mice . In addition to the transgenic data, a substantial amount of information exists regarding mutation of the lacI gene in bacteria . In an effort to centralize the information regarding mutations in the lacI gene in both rodents and bacteria, we have created a computerized database that contains information about DNA sequence alterations on about 500 mutations in transgenic rodents and 8,000 mutations in bacteria . We have also produced a software package for the analysis of the lacI database . Routines have been developed for the analysis of single base substitutions, including programs to (i) determine if two mutational spectra are different; (ii) determine if mutations show a DNA strand bias; (iii) determine the frequency of transitions and transversions; (iv) display the number and kind of mutations observed at each base in the coding region; (v) perform nearest neighbor analysis; and (vi) display mutable amino acids in the lacI protein . The software runs only on IBM-compatible machines running Microsoft Windows . The software and lacI database are freely available via the internet sunsite.unc.edu/dnam/mainpage.++ +html).

Annu Rev Microbiol, 1996, 50, 791 - 824
The F0F1-type ATP synthases of bacteria: structure and function of the F0 complex; Deckers-Hebestreit G et al.; Membrane-bound ATP synthases (F0F1-ATPases) of bacteria serve two important physiological functions . The enzyme catalyzes the synthesis of ATP from ADP and inorganic phosphate utilizing the energy of an electrochemical ion gradient . On the other hand, under conditions of low driving force, ATP synthases function as ATPases, thereby generating a transmembrane ion gradient at the expense of ATP hydrolysis . The enzyme complex consists of two structurally and functionally distinct parts: the membrane-integrated ion-translocating F0 complex and the peripheral F1 complex, which carries the catalytic sites for ATP synthesis and hydrolysis . The ATP synthase of Escherichia coli, which has been the most intensively studied one, is composed of eight different subunits, five of which belong to F1, subunits alpha, beta, gamma, delta, and epsilon (3:3:1:1:1), and three to F0, subunits a, b, and c (1:2:10 +/- 1) . The similar overall structure and the high amino acid sequence homology indicate that the mechanism of ion translocation and catalysis and their mode of coupling is the same in all organisms.

Annu Rev Microbiol, 1996, 50, 625 - 43
Spontaneous mutators in bacteria: insights into pathways of mutagenesis and repair; Miller JH; Mutators are cells that have a higher mutation rate than the wild type . Such mutators have been extensively studied in bacteria, and this has led to the elucidation of a number of important DNA repair pathways, as well as revealing new pathways of mutagenesis . Repair defects in humans that lead to mutator phenotypes are responsible for a number of cancer susceptibilities . In some cases, these repair systems are the close counterparts of the equivalent bacterial repair system . Therefore, characterizing bacterial mutators and the repair systems that are deficient can aid in discovering the human homolog of these systems.

Annu Rev Microbiol, 1996, 50, 513 - 52
Mechanisms of adhesion by oral bacteria; Whittaker CJ et al.; Adherence to a surface is a key element for colonization of the human oral cavity by the more than 500 bacterial taxa recorded from oral samples . Three surfaces are available: teeth, epithelial mucosa, and the nascent surface created as each new bacterial cell binds to existing dental plaque . Oral bacteria exhibit specificity for their respective colonization sites . Such specificity is directed by adhesin-receptor cognate pairs on genetically distinct cells . Colonization is successful when adherent cells grow and metabolically participate in the oral bacterial community . The potential roles of adherence-relevant molecules are discussed in the context of the dynamic nature of the oral econiche.

Annu Rev Microbiol, 1996, 50, 375 - 99
Biosynthesis of halogenated metabolites by bacteria; van Pee KH; Halogenated metabolites, originally thought to be infrequent in nature, are actually nothing unusual at all, and are produced by many different organisms, including bacteria . Whereas marine bacteria usually produce brominated compounds, terrestrial bacteria preferentially synthesize chlorometabolites, but fluoro- and iodometabolites can also be found . Haloperoxidases, enzymes capable of catalyzing the formation of carbon halogen bonds in the presence of hydrogen peroxide and halide ions (Cl-, Br- and I-) have been isolated and characterized from different bacteria . These enzymes turned out to be very unspecific and are obviously not the type of halogenating enzymes responsible for the formation of halometabolites in bacteria . A yet-unknown type of halogenating enzyme having both substrate and regio-specificity must be involved in the biosynthesis of halogenated compounds.

Genetica, 1996 Jan, 97(1), 87 - 101
Spontaneous mutations in bacteria: chance or necessity?
MacPhee DG, Ambrose M.
Several investigators have recently reported that significant numbers of appropriately adapted mutants can be induced in bacterial and yeast strains by exposing stationary phase cells to specific environmental challenges . The resulting mutants are said to be both selection-induced and demonstrably non-random in origin; if this interpretation is correct, it is in direct conflict with the conventional neo-Darwinian view, which is that spontaneous mutants are truly random in origin and arise without the intervention of any overtly adaptive forces . We believe that there are alternative ways of accounting for the appearance of many (and probably all) of the additional mutants which proponents of the adaptive mutation theory claim are observed only after they applied the appropriate selective pressure . Having reviewed the available evidence, we consider that most (if not all) of the sorts of mutants which are said to have been induced following exposure of stationary-phase cells to intense selective pressure are equally likely to have been generated during the operation of certain well-known, conventional (and essentially random) cellular DNA repair processes . Evidence in support of our view can be found in the mainstream literature on the origins of spontaneous mutations . We also note that some of the molecular models which have recently been proposed to explain the production of selection-induced mutations preferentially (or even only) in genes of adaptive significance may turn out to be of considerable interest in their own right, even although the mutants whose origins they were intended to explain may turn out to have arisen in a manner which is totally independent of the conditions used for their selection.

Caries Res, 1996, 30(1), 65 - 70
Effect of sucrose intake on numbers of bacteria in plaque expressing extracellular carbohydrate metabolizing enzymes; Mikkelsen L; The effect of sucrose intake versus a sucrose-free diet (substituting glucose for sucrose) on numbers of isolates from early dental plaque expressing extracellular carbohydrate metabolizing enzymes was studied . The bacteria were isolated from 0- to 3-day-old dental plaque formed on the buccal surface of a lower premolar in 6 subjects . A total of 7,987 isolates were tested for the following activities: synthesis of glucan from sucrose, glucanase, fructanase, synthesis of polymers from glucose, and amylase . Sucrose intake was associated with relatively low numbers of isolates expressing the enzyme activities studied at the start of plaque formation and relatively high numbers in 2- and 3-day plaque . The enzyme activities studied are important elements in the pathophysiology of dental caries and may even be addressed as virulence factors.

Rev Inst Med Trop Sao Paulo, 1996 Jan-Feb, 38(1), 9 - 14
Aerobic bacteria, Chlamydia trachomatis, Pneumocystis carinii and Cytomegalovirus as agents of severe pneumonia in small infants; Ejzenberg B et al.; The authors studied 58 infants hospitalized for pneumonia in a semi-intensive care unit . Age ranged from 1 complete to 6 incomplete months . The infants were sent from another hospital in 20 cases and from home in a further 38 . Pulmonary involvement, which was alveolar in 46 cases and interstitial in 12, was bilateral in 31 children . The investigation was carried out prospectively on the etiological agents associated with respiratory infection to look for evidence of aerobic bacteria (blood cultures), Chlamydia trachomatis and Cytomegalovirus (serology), and Pneumocystis carinii (direct microscopy of tracheal aspirated material) . The following infectious agents were diagnosed in 21 children (36.2%): Aerobic bacteria (8), Chlamydia trachomatis (5), Pneumocystis carinii (3), Cytomegalovirus (3), Cytomegalovirus and Chlamydia trachomatis (1), Aerobic bacteria and Cytomegalovirus (1) . Seven cases of infection by Chlamydia trachomatis and/or Cytomegalovirus were diagnosed out of the 12 cases with pulmonary interstitial involvementPIP: This paper reports the results of a prospective study designed to evaluate the occurrence of potential pulmonary pathogens in a group of socioeconomically deprived infants hospitalized in a semi-intensive care unit for severe pneumonia . The study was conducted over a 2-year period and included infants ranging in age from 1 complete to 6 incomplete months . Inclusion criteria for this study were: a) history of acute respiratory disease; b) respiratory rate over 60 times/minute; and c) radiographic exam revealing alveolar or interstitial pulmonary alteration . A total of 58 infants were selected for the study, of which 33 (56.9%) were male and the 25 (43.1%) were female . Mean age was 2.3 months . Pulmonary involvement, which was alveolar in 46 (79.3%) patients and interstitial in 12 (20.7%) patients, was bilateral in 31 (53.4%) infants . The investigation of etiological agents associated with respiratory infection sought evidence of aerobic bacteria (blood cultures), Chlamydia trachomatis and Cytomegalovirus (serology), and Pneumocystis carinii (direct microscopic exam of tracheal aspirate) . The following infectious agents were diagnosed in 21 (36.2%) patients: aerobic bacteria (8), C . trachomatis (5), P . carinii (3), Cytomegalovirus (3), Cytomegalovirus and C . trachomatis (1), aerobic bacteria and Cytomegalovirus (1) . 7 of 12 (58.3%) cases with pulmonary interstitial involvement were infections by C . trachomatis and/or Cytomegalovirus . The authors recommend that the investigation of the role of other infectious agents for this age bracket should continue .

Rapid Commun Mass Spectrom, 1996, 10(10), 1227 - 32
Rapid identification of intact whole bacteria based on spectral patterns using matrix-assisted laser desorption/ionization with time-of-flight mass spectrometry; Holland RD et al.; Matrix assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS) was investigated as a method for the rapid identification of whole bacteria, either by comparison with archived reference spectra or by co-analysis with cultures of known bacteria . Bacteria were sampled from colonies on an agar plate, mixed with the matrix, air-dried, and introduced in batches into the mass spectrometer for analysis . In the first experiment, both bacterial strains that had been previously analyzed to obtain reference spectra and other strains that had not been analyzed were blind-numbered and their spectra were obtained . Those strains that matched reference spectra were found to be correctly identified . A second experiment involved co-analysis of reference strains and bind-numbered strains under identical conditions; species-specific identification was demonstrated by comparison of spectra of the blind-numbered strains with those of the standards . In all of the spectra obtained in these experiments, each bacterial strain showed a few characteristic high-mass ions which are thought to be derived from bacterial proteins . This work represents the first reported instance of successful bacterial chemotaxonomy by MALDI-TOFMS analysis of whole cells . For the strains tested, the method is rapid and simple.

Lab Anim, 1996 Jan, 30(1), 46 - 50
Translocation of bacteria from the gastrointestinal tract in immunodeficient mice; Ohsugi T et al.; Host defence mechanisms associated with the inhibition of translocation of bacteria from the gastrointestinal (GI) tract were investigated in SCID and beige mice after decontamination with oral antibiotics and colonization with Escherichia coli C25 . SCID mice, which have impaired T and B cell function, tended to have a greater incidence of bacterial translocation from the GI tract up to 7 days after inoculation compared with controls . However, after 7 days both SCID and controls cleared the E . coli C25 from the liver, spleen, blood and peritoneal cavity . Beige mice, with impaired NK cell and polymorphonuclear leukocyte function, were not able to clear the inoculated bacteria from their liver by 14 days after inoculation although the controls were cleared by 7 days . Numbers of bacteria in the mesenteric lymph nodes (MLN) of beige mice did not decrease significantly by 14 days after inoculation, whereas numbers in SCID mice decreased markedly within 7 days . These results suggest that defence mechanisms other than T and B cell function are important in the inhibition of systemic infection from the GI tract.

Arch Microbiol, 1996 Jan, 165(1), 1 - 8
Sec-dependent preprotein translocation in bacteria; den Blaauwen T et al.; Translocation of precursor proteins across the cytoplasmic membrane in bacteria is mediated by a multisubunit protein complex termed translocase, which consists of the integral membrane heterotrimer Sec YEG and the peripheral homodimeric ATPase SecA . Preproteins are bound by the cytosolic molecular chaperone SecB and targeted in a complex with SecA to the translocation site at the cytoplasmic membrane . This interaction with Sec YEG allows the SecA/preprotein complex to insert into the membrane by binding of ATP to the high affinity nucleotide binding site of SecA . At that stage, presumably recognition and proofreading of the signal sequence occurs . Hydrolysis of ATP causes the release of the preprotein in the translocation channel and drives the withdrawal of SecA from the membrane-integrated state . Hydrolysis of ATP at the low-affinity nucleotide binding site of SecA converts the protein into a compact conformational state and releases it from the membrane . In the absence of the proton motive force, SecA is able to complete the translocation stepwise by multiple nucleotide modulated cycles.

Microbiology, 1996 Jan, 142 ( Pt 1), 17 - 32
Phylogenetic analyses of the homologous transmembrane channel-forming proteins of the F0F1-ATPases of bacteria, chloroplasts and mitochondria; Blair A et al.; Sequences of the three integral membrane subunits (subunits a, b and c) of the F0 sector of the proton-translocating F-type (F0F1-) ATPases of bacteria, chloroplasts and mitochondria have been analysed . All homologous-sequenced proteins of these subunits, comprising three distinct families, have been identified by database searches, and the homologous protein sequences have been aligned and analysed for phylogenetic relatedness . The results serve to define the relationships of the members of each of these three families of proteins, to identify regions of relative conservation, and to define relative rates of evolutionary divergence . Of these three subunits, c-subunits exhibited the slowest rate of evolutionary divergence, b-subunits exhibited the most rapid rate of evolutionary divergence, and a-subunits exhibited an intermediate rate of evolutionary divergence . The results allow definition of the relative times of occurrence of specific events during evolutionary history, such as the intragenic duplication event that gave rise to large c-subunits in eukaryotic vacuolar-type ATPases after eukaryotes diverged from archaea, and the extragenic duplication of F-type ATPase b-subunits that occurred in blue-green bacteria before the advent of chloroplasts . The results generally show that the three F0 subunits evolved as a unit from a primordial set of genes without appreciable horizontal transmission of the encoding genetic information although a few possible exceptions were noted.

Int J Syst Bacteriol, 1996 Jan, 46(1), 81 - 7
Two coryneform bacteria isolated from the surface of French Gruyère and Beaufort cheeses are new species of the genus Brachybacterium: Brachybacterium alimentarium sp . nov . and Brachybacterium tyrofermentans sp . nov; Schubert K et al.; New species names, Brachybacterium alimentarium and Brachybacterium tyrofermentans, are proposed for two coryneform bacteria isolated from the surfaces of Gruyere and Beaufort cheeses . These two species are similar in their biochemical and chemotaxonomic characteristics but distinct from previously described bacteria . The most distinctive characteristics are the presence of meso-diaminopimelic acid-containing peptidoglycan with a D-Glu-D-Asp interpeptide bridge and the presence of erythritol teichoic acids that contain diaminoglucuronic acid (an uncommon substituent) . The menaquinone pattern of these organisms is unique among coryneform bacteria . DNA-DNA hybridization experiments revealed that the level of hybridization between the two organisms is 15%, which indicates that they are distinct species . Despite the unique biochemical characteristics of these bacteria, a 16S rRNA sequence comparison revealed that they are unquestionably related to Brachybacterium faecium, Brachybacterium nesterenkovii, and Brachybacterium conglomeratum . DNA-DNA hybridization experiments performed with these three species, B . alimentarium, and B . tyrofermentans revealed that the levels of complementarity ranged from 11 to 38%, values that are similar to the values obtained for Brachybacterium strains described previously . With the inclusion of B . alimentarium and B . tyrofermentans the genus Brachybacterium becomes somewhat heterogeneous with respect to chemotaxonomic characteristics.

Curr Opin Struct Biol, 1995 Dec, 5(6), 794 - 7
Light-harvesting mechanisms in purple photosynthetic bacteria; Isaacs NW et al.; The processes by which photosynthetic bacteria capture light and transfer the energy to the reaction centre continue to be studied using an array of methodologies, both physical and biological . With the publication this year of the crystal structure of the LH2 complex from Rhodopseudomonas acidophila and the projection structure of the LH1 complex from Rhodospirillum rubrum, structural models now exist for all the components in the bacterial photosynthetic apparatus.

Curr Opin Genet Dev, 1995 Dec, 5(6), 734 - 8
Genome evolution in enteric bacteria; Ochman H et al.; For more than a decade, the study of bacterial evolution has been dominated by the comparative analysis of nucleotide sequences within and among species . This approach, combined with the characterization of extensive regions of the chromosome by pulsed-field gel electrophoresis, has led to new insights into the dynamics of bacterial genomes.

Biophys J, 1995 Dec, 69(6), 2211 - 25
Energy transfer in spectrally inhomogeneous light-harvesting pigment-protein complexes of purple bacteria; Hess S et al.; Energy transfer within the peripheral light-harvesting antenna of the purple bacteria Rhodobacter sphaeroides and Rhodopseudomonas palustris was studied by one- and two-color pump-probe absorption spectroscopy with approximately 100-fs tunable pulses at room temperature and at 77 K . The energy transfer from B800 to B850 occurs with a time constant of 0.7 +/- 0.05 ps at room temperature and 1.8 +/- 0.2 ps at 77 K and is similar in both species . Anisotropy measurements suggest a limited but fast B800 <--> B800 transfer time (tau approximately 0.3 ps) . This is analyzed as incoherent hopping of the excitation in a system of spectrally inhomogeneous antenna pigment-protein complexes, by a master equation approach . The simulations show that the measured B800 dynamics is well described as energy transfer with a characteristic average nearest-neighbor pairwise transfer time of 0.35 ps among approximately 10 Bchl molecules in a circular arrangement, in good agreement with the recent high-resolution structure of LH2 . The possible presence of fast intramolecular relaxation processes within the Bchl a molecule was investigated by measurement of time-resolved difference absorption spectra and kinetics of Bchl a in solution and in low-temperature glasses . From these measurements it is concluded that fast transients observed at room temperature are due mainly to solvation processes, whereas at 77 K predominantly slower (> 10-ps) relaxation occurs.

J Chromatogr A, 1995 Dec 1, 718(1), 211 - 5
Use of capillary zone electrophoresis in an investigation of peptide uptake by dairy starter bacteria; Moore IL et al.; A capillary zone electrophoresis (CZE) method to separate the peptide series val-glyn, where n is 1 to 4, has been evaluated and compared to separation by reversed-phase high-performance liquid chromatography (RP-HPLC) . The method was able to quantitate peptides present a very low concentrations (down to 0.05 mM) with high reproducibility and accuracy and was capable of separating peptides differing in size by only a single glycine residue . It could also separate the peptides val-gly and leu-gly which differed in only a single side-chain methylene group . The method was fast, required small sample volumes, and proved to be superior to RP-HPLC . The suitability of the CZE method to analyze peptide uptake by dairy starter bacteria is discussed.

Appl Environ Microbiol, 1995 Dec, 61(12), 4505 - 9
Development of a sensitive chemiluminometric assay for the detection of beta-galactosidase in permeabilized coliform bacteria and comparison with fluorometry and colorimetry; Van Poucke SO et al.; We developed a chemiluminometric assay of beta-galactosidase in coliform bacteria, using a phenylgalactose-substituted 1,2-dioxetane derivative as a substrate . Permeabilization of cells is required to ensure the efficient cellular uptake of this compound . By this method, one coliform seeded in 100 ml of sterile water can be detected after a 6- to 9-h propagation phase followed by a 45-min enzyme assay in the presence of polymyxin B . Compared with fluorometry and colorimetry, chemiluminometry afforded 4- and 1,000-fold increases in sensitivity and 1- and 6-h increases in the speed of detection, respectively.

Appl Environ Microbiol, 1995 Dec, 61(12), 4436 - 40
Natural assemblages of marine bacteria exhibiting high-speed motility and large accelerations; Mitchell JG et al.; Natural communities of marine bacteria, an isolate (FMB-Bf3) from one marine community, and Escherichia coli were examined by video microscopy for the magnitude and uniformity of their speed . Natural communities formed tight microswarms that showed higher speeds (mean = 230 microns s-1) than did E . coli (15 microns s-1) or FMB-Bf3 (mean = 62 microns s-1) . Outside the microswarms, the marine bacteria slowed to 45 microns s-1 . Between turns, in mid run, and while travelling in straight lines, the natural-community bacteria accelerated up to 1,450 microns s-2 while the cultured bacteria showed maximum accelerations of 70 and 166 microns s-2 . The frequency distribution of speed change for the marine bacteria was skewed towards a few large negative accelerations and a range of positive accelerations . The general pattern was one of relatively slow increases in speed followed by abrupt declines . The results indicate that the mechanical generation and energetic maintenance, as well as the environmental function, of bacterial motility need reappraisal . We conclude that the standard bacterial motility parameters of low and uniform speed, derived from culture-based studies, are not necessarily applicable to marine bacterial communities.

Genes Dev, 1995 Dec 1, 9(23), 2888 - 902
The SIR2 gene family, conserved from bacteria to humans, functions in silencing, cell cycle progression, and chromosome stability; Brachmann CB et al.; Genomic silencing is a fundamental mechanism of transcriptional regulation, yet little is known about conserved mechanisms of silencing . We report here the discovery of four Saccharomyces cerevisiae homologs of the SIR2 silencing gene (HSTs), as well as conservation of this gene family from bacteria to mammals . At least three HST genes can function in silencing; HST1 overexpression restores transcriptional silencing to a sir2 mutant and hst3 hst4 double mutants are defective in telomeric silencing . In addition, HST3 and HST4 together contribute to proper cell cycle progression, radiation resistance, and genomic stability, establishing new connections between silencing and these fundamental cellular processes.

J Mol Biol, 1995 Nov 10, 253(5), 739 - 48
Autocatalytic gene expression occurs via transertion and membrane domain formation and underlies differentiation in bacteria: a model; Norris V et al.; When bacteria contain two chromosomes, two or more copies of the same gene are present in the same cytoplasm and, if these copies are subject to negative regulation in trans and positive (autocatalytic) regulation in cis, one copy will be expressed at the expense of the other copy(ies) . This autocatalytic process depends on the coupled transcription, or translation and insertion of nascent proteins into the membrane, or transertion . Transertion is responsible for looping genes out of the nucleoid and increasing their accessibility to transcription factors . Transertion of proteins with lipid preferences creates proteolipid domains in the membrane . These domains fuse to give two types of large domains, each associated with the expression of a particular set of genes . These large domains organize kinases, proteases and transcription factors and result in the expression of one set of genes encoding proteins with common lipid preferences from one chromosome and expression of a different set from the other . These intracellular differences underlie the production of different progeny by cell division that follows, for example, reception of extracellular signals, and that constitutes differentiation in bacteria.

J Biol Chem, 1995 Nov 3, 270(44), 26670 - 6
Characterization of the nucleotide binding properties and ATPase activity of recombinant hamster BiP purified from bacteria; Wei J et al.; HSP70 family proteins bind ATP and hydrolyze it, but the precise role of these activities in their in vivo chaperoning function has not been determined . In this report, we characterized wild-type hamster BiP isolated from bacteria in terms of its ATP binding and ATPase activities . Recombinant BiP behaved essentially the same as endogenous BiP in terms of oligomeric status, protease digestion patterns, and ATPase properties . By engineering a Factor Xa cleavable site following the His tag which was used for affinity purification, we demonstrated that the six histidines had no effect on either the structural or ATPase properties of recombinant BiP . We also found that bacteria-synthesized BiP had a tightly bound ADP that was resistant to dialysis . Removal of the bound nucleotide allowed us to directly measure the binding affinity of ATP and ADP to BiP (Kd of 0.2 microM for ATP and 0.29 microM for ADP) by equilibrium dialysis . Careful characterization of wild-type BiP will allow us to use this system to characterize BiP ATP binding site mutants that can be used to probe the role of ATP binding and ATPase activity in BiP functions.

Antonie Van Leeuwenhoek, 1995 Nov, 68(4), 281 - 4
Role of formate and hydrogen in the degradation of propionate and butyrate by defined suspended cocultures of acetogenic and methanogenic bacteria; Stams AJ et al.; The butyrate-degrading Syntrophospora bryantii degrades butyrate and a propionate-degrading strain (MPOB) degrades propionate in coculture with the hydrogen- and formate-utilizing Methanospirillum hungatii or Methanobacterium formicicum . However, the substrates are not degraded in constructed cocultures with two Methanobrevibacter arboriphilus strains which are only able to consume hydrogen . Pure cultures of the acetogenic bacteria form both hydrogen and formate during butyrate oxidation with pentenoate as electron acceptor and during propionate oxidation with fumarate as electron acceptor . Using the highest hydrogen and formate levels which can be reached by the acetogens and the lowest hydrogen and formate levels which can be maintained by the methanogens it appeared that the calculated formate diffusion rates are about 100 times higher than the calculated hydrogen diffusion rates.

Mol Microbiol, 1995 Nov, 18(3), 383 - 90
Quelling the red menace: haem capture by bacteria; Lee BC; Haem is an important bacterial nutrient . As a prosthetic group of several proteins, haem functions as a cofactor mediating oxygen transport, energy generation, and mixed-function oxidation . In addition, the iron chelated in the porphyrin ring may serve as an iron substrate for growth . However, because of its propensity for oxidizing cellular constituents, haem is always associated with proteins . Therefore, the uptake and transit of haem across bacterial membranes requires the participation of protein escorts . Bacteria have evolved a diverse array of surface-exposed receptors dedicated to binding haem and haem-proteins . Following this selective recognition at the bacterial cell surface, haem is transported across the outer membrane via a TonB-dependent process . The control of receptor expression appears to be multifactorial, probably involving a number of global regulators . A model integrating this information is presented.

Mikrobiologiia, 1995 Nov-Dec, 64(6), 751 - 5
{Luminescent bacteria--producers of specific restriction endonucleases}; Repin VE et al.; Luminescent bacteria isolated from the waters of the Black Sea and of the Indian and Pacific Oceans were tested for the presence of restriction endonucleases . For 12 of 19 restriction enzyme producers revealed, restriction sites were determined . The enzymes were identified as isoschizomers of AfIII, BanI, HaeIII, PstI, Sau3AI, and Sau96I . Possible participation of the restriction and modification enzymes in the interaction of bacterial symbionts with the animal macrosymbiont is discussed.

Res Vet Sci, 1995 Nov, 59(3), 272 - 4
Segmented filamentous bacteria associated with lymphoid tissues in the ileum of horses; Lowden S et al.; Segmented filamentous bacteria preferentially attached to the follicle-associated epithelium overlying the lymphoid tissue in samples of the terminal ileum from seven horses examined by scanning electron microscopy . The bacteria adhered to the apical membrane of the enterocytes by a holdfast segment . Each filament tended to be of uniform diameter, but the filaments ranged from 0.7 to 1.4 microns in diameter . The bacteria were usually absent from the adjacent villous epithelium.

FEMS Microbiol Lett, 1995 Nov 1, 133(1-2), 169 - 73
An agarose slide method to follow the fate of bacteria within digestive vacuoles of protozoa; Schlimme W et al.; A method to follow the fate of ingested bacteria within digestive vacuoles of protozoa is presented . Tetrahymena pyriformis, previously fed with bacteria, is deposited onto glass microscope slides covered with a film of nutritive agarose . The protozoa lyse and the digestive vacuoles containing the bacteria stay undamaged and can be observed microscopically . After incubation, microcolonies reveal those vacuoles which contained living bacteria . The method can be used to study the survival ability of the ingested bacteria . It is a potentially valuable technique for studies on digestion efficacy, virulence ability, or escape mechanisms of bacteria from digestion.

Proc Natl Acad Sci U S A, 1995 Oct 10, 92(21), 9757 - 61
Chemotactic signal integration in bacteria; Khan S et al.; Chemotactic signaling in Escherichia coli involves transmission of both negative and positive signals . In order to examine mechanisms of signal processing, behavioral responses to dual inputs have been measured by using photoactivable "caged" compounds, computer video analysis, and chemoreceptor deletion mutants . Signaling from Tar and Tsr, two receptors that sense amino acids and pH, was studied . In a Tar deletion mutant the photoactivated release of protons, a Tsr repellent, and of serine, a Tsr attractant, in separate experiments at pH 7.0 resulted in tumbling (negative) or smooth-swimming (positive) responses in ca . 50 and 140 ms, respectively . Simultaneous photorelease of protons and serine resulted in a single tumbling or smooth-swimming response, depending on the relative amounts of the two effectors . In contrast, in wild-type E . coli, proton release at pH 7.0 resulted in a biphasic response that was attributed to Tsr-mediated tumbling followed by Tar-mediated smooth-swimming . In wild-type E . coli at more alkaline pH values the Tar-mediated signal was stronger than the Tsr signal, resulting in a strong smooth-swimming response preceded by a diminished tumbling response . These observations imply that (i) a single receptor time-averages the binding of different chemotactic ligands generating a single response; (ii) ligand binding to different receptors can result in a nonintegrated response with the tumbling response preceding the smooth-swimming response; (iii) however, chemotactic signals of different intensities derived from different receptors can also result in an apparently integrated response; and (iv) the different chemotactic responses to protons at neutral and alkaline pH may contribute to E . coli migration toward neutrality.

Proc Natl Acad Sci U S A, 1995 Oct 10, 92(21), 9598 - 602
Intracellular coexistence of methano- and thioautotrophic bacteria in a hydrothermal vent mussel; Distel DL et al.; The coexistence of two phylogenetically distinct symbiont species within a single cell, a condition not previously known in any metazoan, is demonstrated in the gills of a Mid-Atlantic Ridge hydrothermal vent mussel (family Mytilidae) . Large and small symbiont morphotypes within the gill bacteriocytes are shown to be separate bacterial species by molecular phylogenetic analysis and fluorescent in situ hybridization . The two symbiont species are affiliated with thioautotrophic and methanotrophic symbionts previously found in monospecific associations with closely related mytilids from deep-sea hydrothermal vents and hydrocarbon seeps.

Virus Res, 1995 Oct, 38(2-3), 205 - 18
The use of African horse sickness virus NS3 protein, expressed in bacteria, as a marker to differentiate infected from vaccinated horses; Laviada MD et al.; Segment 10 of the double-stranded RNA (dsRNA) genome from African horse sickness virus serotype 4 (AHSV-4) was cloned and sequenced . The sequence of the coding region showed a total length of 667 bp . Nucleotide comparisons showed a 95% sequence similarity between serotypes 4 and 9, and 76% between serotypes 4 and 3 . cDNA clones containing the coding region were cloned in the vector pET3xb and expressed in Escherichia coli . The NS3 gene product was synthesised at very high level as an insoluble fusion protein . The recombinant protein was used in a differential ELISA to distinguish horses that were infected with AHSV-4 or vaccinated with live-modified virus from those vaccinated with a purified inactivated vaccine . The results obtained indicate that recombinant NS3 can indeed differentiate between infected and vaccinated animals implying that this recombinant could be developed as a diagnostic reagent, and it would allow the mobility of vaccinated horses . Thus, economical losses associated with this disease could be avoided.

Antonie Van Leeuwenhoek, 1995 Oct, 68(3), 253 - 60
Resolution of batch variations in pyrolysis mass spectrometry of bacteria by the use of artificial neural network analysis; Freeman R et al.; A simple, but stringent, three group model of bacterial interstrain identity (two cultures of the same strain of Escherichia coli) and difference (a culture of a serologically distinct strain) was used in multiple serial weekly subcultures for five weeks to demonstrate the effect of both growth-related (phenotypic) and machine-related variation on pyrolysis mass spectra . An aliquot of serum from a single sample was included in each pyrolysis batch to distinguish machine drift from culture drift . Conventional principal component (PC) canonical variate (CV) analysis was successful within each pyrolysis batch but the variations between batches precluded the use of data from more than one batch in successful PCCV analysis . In contrast, artificial neural networks (ANNs) trained with data from one batch could be successfully used to identify groups in data from non-contemporaneous pyrolysis batches . Although the ANN method will require validation in more complex settings than this simple model, it is a promising approach to the problem of batch constraint in pyrolysis mass spectrometry.

Protein Expr Purif, 1995 Oct, 6(5), 655 - 64
Reconstitution of active human calcineurin from recombinant subunits expressed in bacteria; Rokosz LL et al.; Calcineurin, a protein phosphatase found in eukaryotic cells, presents a challenging problem in heterologous protein expression because it is both heterodimeric and posttranslationally modified . In this paper, we describe the cloning of both subunits (catalytic A and regulatory B) of calcineurin from a human cDNA library and their expression at high levels in Escherichia coli . The calcineurin A subunit is expressed as an insoluble glutathione S-transferase fusion protein, while the calcineurin B subunit is soluble upon direct expression . Catalytically active holoenzyme is derived from the separately expressed subunits using a three-step refolding protocol . First, the fusion protein is solubilized, then it is cleaved at the fusion junction with thrombin, and, finally, a catalytically competent calcineurin A:calcineurin B:calmodulin complex is reconstituted by cofolding the separately purified components . In addition, we show that a similar refolding protocol can be applied to a C-terminally truncated form of calcineurin A, which lacks an autoinhibitory and calmodulin-binding domain.

Lett Appl Microbiol, 1995 Oct, 21(4), 228 - 9
Sulphate-reducing bacteria in bovine faeces; Carli T et al.; Sulphate-reducing bacteria (SRB) were found in all of 200 bovine faeces examined . The number of SRB in bovine faeces ranged from 5 x 10(2) to 6 x 10(8) bacteria g-1 . Of 50 isolates identified, all were assigned to the genus Desulfovibrio.

Appl Environ Microbiol, 1995 Oct, 61(10), 3549 - 55
Heat-tolerant methanotrophic bacteria from the hot water effluent of a natural gas field; Bodrossy L et al.; Methanotrophic bacteria were isolated from a natural environment potentially favorable to heat-tolerant methanotrophs . An improved colony plate assay was developed and used to identify putative methanotrophic colonies with high confidence . Fourteen new isolates were purified and partially characterized . These new isolates exhibit a DNA sequence homology of up to 97% with the conserved regions in the mmoX and mmoC genes of the soluble methane monooxygenase (MMO)-coding gene cluster of Methylococcus capsulatus Bath . The copper regulation of soluble MMO expression in the same isolates, however, differs from that of M . capsulatus Bath, as the new isolates can tolerate up to 0.8 microM copper without loss of MMO activity while a drastic reduction of MMO activity occurs already at 0.1 microM copper in M . capsulatus Bath . The isolates can be cultivated and utilized at elevated temperatures, and their copper- and heat-tolerant MMO activity makes these bacteria ideal candidates for future biotechnological use.

Biochim Biophys Acta, 1995 Sep 6, 1251(2), 161 - 9
Electron paramagnetic resonance studies of ferric cytochrome c' from photosynthetic bacteria; Fujii S et al.; Electronic ground nature of ferric cytochromes c' isolated from five photosynthetic bacteria . Chromatium vinosum ATCC 17899, Rhodobacter capsulatus ATCC 11166, Rhodopseudomonas palustris ATCC 17001, Rhodospirillum molischianum ATCC 14031, and Rhodospirillum rubrum ATCC 11170 has been investigated by electron paramagnetic resonance (EPR) spectroscopy . EPR spectra indicate that the electronic ground state of five ferric cytochromes c' is a quantum mechanical admixed-spin state of a high spin (S = 5/2) and an intermediate spin (S = 3/2) at pH 7.2 and is high-spin state at pH 11.0 . At physiological pH, however, the content of an intermediate spin state differs with the bacterial source of the protein: approximately 50%, Chromatium vinosum; approximately 40%, Rhodobacter capsulatus and Rhodopseudomonas palustris; approximately 10%, Rhodospirillum molischianum and Rhodospirillum rubrum . Computer simulation of the spectra supports this diversity of the contribution of an intermediate spin state . Model studies of the ferric porphyrin complexes suggest that the correlation between content of an intermediate spin state and heme iron displacement from the mean heme plane . Therefore, the variation of the content of an intermediate spin state observed in the present study reflects the subtle difference in the degree of heme iron displacement among the proteins.

J Clin Periodontol, 1995 Sep, 22(9), 723 - 7
An approach to efficacy screening of mouthrinses: studies on a group of French products (II) . Inhibition of salivary bacteria and plaque in vivo; Harper PR et al.; The aim of this study was to determine the value of screening studies to assess the efficacy of antiseptic mouthrinse products relative to proven products . The products tested were 6 antiseptic mouthrinses available in France . 4 contained chlorhexidine (Eludril, Hibident, Parodex and Prexidine) with Hibident considered the positive control . 1 product contained cetylpyridinium chloride (Alodont) and 1 hexetidine (Hextril) . Saline was used as the negative control . The 1st study assessed the persistence of action of the products by recording salivary bacterial counts before and up to 7 h after single rinses . The 2nd study measured the inhibition of plaque regrowth, from a zero baseline, in the absence of tooth-brushing over a 4-day period . Both studies used blind randomised crossover designs balanced for residual effects . Salivary bacterial count reductions with time were highly significantly greater for Parodex to 5 h and Hibident and Prexidine to 7 h; There were no significant differences between the latter three chlorhexidine rinses except at 3 h, when decrements were significantly less with Parodex . Despite a mean trend in favour, Alodont, Eludril and Hextril were not significantly different from saline . Plaque inhibition by area and index was highly significantly different between products . Hibident, Parodex and Prexidine showed similar plaque inhibition and were significantly more effective than all other rinses . Eludril and Hextril were significantly more effective than saline but Alodont was not . Taken with the associated study in vitro and published reports on the same or similar products, it is apparent that efficacy of a product cannot be assumed merely because it contains a known active plaque inhibitor.(ABSTRACT TRUNCATED AT 250 WORDS)

Appl Environ Microbiol, 1995 Sep, 61(9), 3288 - 92
The cellular location of Prevotella ruminicola beta-1,4-D-endoglucanase and its occurrence in other strains of ruminal bacteria; Gardner RG et al.; Prevotella ruminicola B(1)4, TC1-1, TF1-3, and TS1-5 all produced immunologically cross-reacting 88- and 82-kDa carboxymethyl cellulases (CMCases) . P . ruminicola 23, 118B, 20-63, and 20-78 had much lower CMCase activities, and Western blots (immunoblots) showed no cross-reaction with the B(1)4 CMCase antiserum . Fibrobacter succinogenes S85 and Selenomonas ruminantium HD4 and D produced CMCase, but these enzymes were smaller and did not cross-react with the B(1)4 CMCase antiserum . The B(1)4 CMCase antiserum inhibited the B(1)4, TC1-1, TF1-3, and TS1-5 CMCase activities and agglutinated these cells, but it had no effect on the other strains or species . On the basis of these results, the B(1)4 CMCase is a strain-specific enzyme that is located on the outside surface of the cells . P . ruminicola B(1)4 cultures, grown on sucrose, did not have significant CMCase activity, but these cells could bind purified 88- and 82-kDa CMCase but not 40.5-kDa CMCase . Because the 40.5-kDa CMCase is a fully active, truncated form of the CMCase, it appears that the N-terminal domain of the 88-kDa B(1)4 CMCase anchors the CMCase to the cells . Cells grown on cellobiose produced at least 10-fold more CMCase than the sucrose-grown cells, and the cellobiose-grown cells could only bind 15% as much CMCase as sucrose-grown cells . Virtually all of the CMCase activity of exponentially growing cultures was cell associated, but CMCase activity was eventually detected in the culture supernatant . On the basis of the observation that the 88-kDa CMCase was gradually converted to the 82-kDa CMCase when cultures reached the stationary phase without a change in specific activity, it appears that the 82-kDa protein is probably a proteolytic degradation product of the 88-kDa CMCase.

J Gen Virol, 1995 Sep, 76 ( Pt 9), 2161 - 8
Complete nucleotide sequence of the herpesvirus simiae glycoprotein G gene and its expression as an immunogenic fusion protein in bacteria; Slomka MJ et al.; The nucleotide sequence of a 2384 bp portion within the unique short (Us) region of the herpesvirus simiae (simian herpes B virus; SHBV) genome is presented . A partial and a complete open reading frame (ORF) were found within this nucleotide sequence . The partial ORF encodes the C terminus (147 amino acids) of a protein kinase which is highly conserved in the herpes simplex virus type 1 (HSV-1) and type 2 (HSV-2) and simian agent 8 (SA8) Us regions . The complete ORF is located 3' to the partial ORF within the 2384 bp sequence and encodes a 593 amino acid glycoprotein which appears to be closely related to the SA8 glycoprotein G (gG), but shares little amino acid similarity with gG of HSV-1 and -2 . However, the complete ORF shares certain features conserved among most alphaherpesvirus gGs, notably three highly conserved cysteine residues and an adjacent N-glycosylation site . Therefore, it was concluded that this complete ORF encodes the SHBV gG . The 358 amino acid C-terminal portion of SHBV gG was expressed in Escherichia coli as a fusion protein and this was detected by immunoblotting with sera from cynomolgus monkeys which were either experimentally or naturally infected with SHBV . The purified fusion protein was inoculated into rabbits to raise an antiserum which recognized a number of apparently SHBV gG-specific protein bands in extracts from SHBV-infected simian cells.

Microbiol Res, 1995 Sep, 150(3), 311 - 3
Filamentous soil fungi and unidentified bacteria in drinking water from wells and water mains near Bratislava; Frankova E et al.; The occurrence of filamentous fungi in 294 samples of drinking water taken from wells and taps near Bratislava was studied . Fungal contaminants were found in 192 samples (44%) . 39 genera and 64 species of soil filamentous fungi were identified by routine isolation and cultivation methods . Most of them belong to the Deuteromycetes . In the course of fungal cultivation in Czapek-Dox agar supplemented with 20 mg.l-1 tetracycline, colonies of unknown yellow coloured bacteria were observed.

J Periodontal Res, 1995 Sep, 30(5), 369 - 73
Influence of periodontal bacteria and disease status on V beta expression in T cells; Mathur A et al.; Some bacterial antigens such as S . aureus enterotoxins can selectively stimulate T cells that express specific V beta genes of the T cell antigen receptor (TCR) . The purpose of this study was to investigate whether or not periodontal bacteria could similarly alter the expression of V beta families within the TCR complex . Peripheral blood mononuclear cells (PBMNCs) were isolated from 12 patients with early onset periodontitis and 11 periodontally-healthy controls . PBMNCs were incubated in media alone, or co-cultured for 48 h with heat-inactivated A . actinomycetemcomitans, P . gingivalis and P . intermedia . Expression of five V beta families (V alpha beta 2, V beta 5, V beta 6, V beta 8, and V beta 12) was determined by use of monoclonal antibodies . Mean unstimulated expression of V alpha beta 2 and V beta 8 was significantly higher (p < 0.05) in patients than healthy controls . Co-culture with the three bacteria resulted in significant changes (increases or decreases) in V beta expression in 27% of the trials . There were no significant differences in the number or direction of changes in samples from patients and controls . When compared to unstimulated controls, 18 significant increases but no decreases in the percentage of cell expressing V alpha beta 2, V beta 5 or V beta 6 were noted following co-culture with P . intermedia . Overall, co-culture with P . intermedia significantly (p < 0.05) up-regulated expression of the five V beta families studied . These data suggest that periodontal bacteria may alter V beta expression within the T cell receptor complex.

J Anim Sci, 1995 Aug, 73(8), 2469 - 73
Composition of ruminal bacteria harvested from steers as influenced by dietary forage level and fat supplementation; Hussein HS et al.; The objective of this study was to examine the effects of dietary forage level and fat supplementation on the chemical composition of mixed ruminal bacteria (MRB) . Six ruminally cannulated beef steers (354 kg +/- 18) were given ad libitum access to six diets (13.2% CP; DM basis) that were offered twice daily in a 6 x 6 Latin square design . Treatments were arranged as a 2 x 3 factorial with two forage levels (70 vs 30% of dietary DM as corn silage) and three forms of fat supplementation including no canola seed or canola seed added at 10% of dietary DM as whole treated with alkaline hydrogen peroxide or untreated crushed . Canola seed contributed 5% added fat to the total diet . The remaining dietary ingredients were corn, canola meal, molasses, and urea . No interactions (P > .05) between dietary forage level and canola seed supplementation were observed . Concentrations of OM, N, and all amino acids were higher (P < .05) in MRB from steers fed low forage than in MRB from steers fed high forage . Concentrations of purines and GE and the N:purines ratio in MRB were not affected (P > .05) by dietary forage level or canola seed supplementation . Canola seed supplementation did not affect (P > .05) concentrations of OM, N, or most of the amino acids in MRB . Concentrations of four essential amino acids (i.e., isoleucine, leucine, lysine, and phenylalanine) in MRB were decreased (P < .05) due to canola seed supplementation . Dietary forage level did not affect (P > .05) concentrations of long-chain fatty acids in MRB.(ABSTRACT TRUNCATED AT 250 WORDS)

Lett Appl Microbiol, 1995 Aug, 21(2), 99 - 102
Beta-D-galactosidase activity of viable, non-culturable coliform bacteria in marine waters; Davies CM et al.; The beta-D-galactosidase activity of viable but non-culturable (vnc) Escherichia coli cells in seawater was investigated using a rapid fluorimetric enzyme assay . Results from microcosm studies showed that loss of culturability did not necessarily result in loss of the ability to produce the galactosidase enzyme . Even when no culturable cells were detected, a positive enzyme assay response was observed and the activity of the inducible enzyme over time more closely reflected the number of vnc cells present.

J Clin Microbiol, 1995 Aug, 33(8), 2002 - 6
Human Bordetella bronchiseptica infection related to contact with infected animals: persistence of bacteria in host; Gueirard P et al.; Within a period of 2 1/2 years, Bordetella bronchiseptica was isolated four times from a 79-year-old woman with bronchopneumonia . We have demonstrated by pulsed-field gel electrophoresis that this infection was related to contact with infected rabbits . The initial human B . bronchiseptica isolate had a phenotype characteristic of usual B . bronchiseptica clinical isolates; it produced toxin and adhesins, such as adenylate cyclase-hemolysin, filamentous hemagglutinin, and pertactin, and was able to induce lethality in a murine respiratory model . By contrast, although the three successive human isolates produced adhesins, they did not express adenylate cyclase-hemolysin and were unable to induce lethality . This implies that adenylate cyclase-hemolysin is required to induce lethality . We suggest that B . bronchiseptica may persist in the host, with expression of adenylate cyclase-hemolysin being essential for the initiation of infection and expression of adhesins being essential for persistence.

FEBS Lett, 1995 Jul 17, 368(2), 370 - 2
Excitation delocalization over the whole core antenna of photosynthetic purple bacteria evidenced by non-linear pump-probe spectroscopy; Novoderezhkin VI et al.; Anomalously high values of photoinduced absorption changes were revealed in the antenna of photosynthetic purple bacteria . They were found to be 4-16 times greater at the bleaching peak of the antenna than at the bleaching peak of the BChl dimer of the reaction center . This is direct proof of excitation delocalization over many pigment molecules . Calculations according to the model of exciton delocalization over all core antenna BChls allow one to explain the observed phenomenon.

FEMS Microbiol Lett, 1995 Jul 15, 130(1), 7 - 12
Most probable number enumeration of H2-utilizing acetogenic bacteria from the digestive tract of animals and man; Dore J et al.; A method is proposed that allows the enrichment and most probable number estimation of H2/CO2(-)utilizing acetogenic bacteria . It is based on the difference in acetate production for serial dilutions incubated under either a test H2/CO2 (4:1), or a control N2/CO2 (4:1) headspace atmosphere . A nutritionally non-selective medium was used, containing bromoethane-sulfonic acid as inhibitor of methanogenic archaea and 10% pre-incubated clarified rumen fluid . Acetogenic bacteria were enumerated in rumen and hindgut contents of animals and in human feces . They ranged from below 10(2) to above 10(8) per gram wet weight gut content and their population levels were the highest in the absence of methanogenesis . The method described therein should prove useful to better understand the diversity and ecological importance of dominant gut acetogens.

Nature, 1995 Jul 6, 376(6535), 49 - 53
Dynamics of formation of symmetrical patterns by chemotactic bacteria; Budrene EO et al.; Motile cells of Escherichia coli aggregate to form stable patterns of remarkable regularity when grown from a single point on certain substrates . Central to this self-organization is chemotaxis, the motion of bacteria along gradients of a chemical attractant that the cells themselves excrete . Here we show how these complex patterns develop . The long-range spatial order arises from interactions between two multicellular aggregate structures: a 'swarm ring' that expands radially, and focal aggregates that have lower mobility . Patterning occurs through alternating domination by these two sources of excreted attractant (which we identify here as aspartate) . The pattern geometries vary in a systematic way, depending on how long an aggregate remains active; this depends, in turn, on the initial concentration of substrate (here, succinate).

J Periodontal Res, 1995 Jul, 30(4), 264 - 71
Effect of whole oral bacteria and extracted lipopolysaccharides on peripheral blood leukocyte interleukin-2 receptor expression; Lindemann RA et al.; Expression of the interleukin-2 receptor (IL-2R) on T cells is the molecular mechanism that initiates the G0 to G1 transition and is the critical first step for T cell proliferation in response to antigen . The effect of whole periodontal bacteria and lipopolysaccharides (LPS) on peripheral blood mononuclear cell (PBMC) IL-2R expression was examined in vitro . LPS induced a modest but significant increase in high affinity IL-2R alpha/beta (p55/p75 positive) expression on PBMC over untreated cells after 48 h culture . Addition of LPS to PBMC cultures depleted of monocytes had no effect on IL-2R expression compared to untreated cultures . Interleukin-1 (IL-1) caused a similar effect to LPS in 48 h PBMC cultures but IL-1 also increased high affinity IL-2R expression in cultures depleted of adherent mononuclear cells . When antibody to IL-1 was simultaneously added with LPS to PBMC cultures, the high affinity IL-2R inductive effect was reversed at 48 h, suggesting that the LPS effect on PBMC IL-2R was indirect, via monocytes . Whole pathogenic oral bacteria cultured with PBMC at high (100:1), but not low (10:1) bacteria:PBMC ratios had a similar effect to LPS, inducing high affinity IL-2R expression at 48 h . Increases in soluble IL-2R alpha were also measured in supernatants of PBMC incubated with periodontal bacteria compared to untreated controls . In this system, a critical threshold of bacteria was required to activate PBMC perhaps related to the quantity of cell-surface LPS presented to adherent mononuclear cells.

J Clin Periodontol, 1995 Jul, 22(7), 510 - 5
Effect of periodontal treatments on serum IgG antibody titers against periodontopathic bacteria; Horibe M et al.; Serum IgG antibody titers to 7 periodontopathic bacteria in periodontitis patients were measured at the 1st visit and after various periodontal treatments with clinically successful improvement, in order to evaluate what kind of factors are associated with changes of serum antibody titers . 20 patients (10 male and 10 female from 23 to 61 years old) with adult, rapidly progressive periodontitis were enrolled in this study . All patients received initial preparation and most of them also underwent surgical procedure . After the treatments, the mean probing pocket depths decreased from 3.72 mm to 1.56 mm . Serum samples were collected from patients at the initial and final examinations . Serum IgG antibody titers against sonicated antigens of Porphyromonas gingivalis FDC 381, Prevotella intermedia ATCC 25611, Prevotella loescheii ATCC 15930, Fusobacterium nucleatum subspecies nucleatum ATCC 25586, Actinobacillus actinomycetemcomitans FDC Y4, Eikenella corrodens FDC 1073 and Capnocytophaga ochracea # M 12 were determined by enzyme-linked immunosorbent assay . The mean antibody titers to P . gingivalis and P . intermedia decreased significantly after the treatment as compared to their pretreatment levels . The antibody titer to P . gingivalis, especially, decreased in all of the patients examined . A significant relationship was found between the decreased antibody titer to P . gingivalis and the number of teeth which received periodontal surgery, as well as treatment length, and the relationship between the decreased antibody titer to P . intermedia and the number of extracted teeth was also significant . These results suggest that the changes of serum IgG titers against P . gingivalis and P . intermedia are related to the suppression of such pathogens in subgingival plague.

Mol Microbiol, 1995 Jul, 17(2), 205 - 10
Programmed cell death in bacteria: proteic plasmid stabilization systems; Jensen RB et al.; Bacterial plasmids are stabilized by a number of different mechanisms . Here we describe the molecular aspects of a group of plasmid-encoded gene systems called the proteic killer gene systems . These systems mediate plasmid maintenance by selectively killing plasmid-free cells (post-segregational killing or plasmid addiction) . The group includes ccd of F, parD/pem of R1/R100, parDE of RP4/RK2, and phd/doc of P1 . All of these systems encode a stable toxin and an unstable antidote . The antidotes prevent the lethal action of their cognate toxins by forming tight complexes with them . The antidotes are degraded by cellular proteases . Thus, the different decay rates of the toxins and antidotes seem to be the molecular basis of toxin activation in plasmid-free cells . The operons encoding the toxins and antidotes are autoregulated at the level of transcription either by a complex formed by the toxins and the cognate antidotes or by the antidote alone . The cellular targets of the killer proteins have been determined to be DNA gyrase in the case of ccd of F and DnaB in the case of parD of R1 . Surprisingly, the Escherichia coli chromosome encodes at least two of these peculiar gene systems.

FEBS Lett, 1995 Jun 26, 367(2), 107 - 11
The proton-pumping respiratory complex I of bacteria and mitochondria and its homologue in chloroplasts; Friedrich T et al.; The proton-pumping NADH:ubiquinone oxidoreductase, also called complex I, is the first of the respiratory complexes providing the proton motive force which is essential for the synthesis of ATP . Closely related forms of this complex exist in the mitochondria of eucaryotes and in the plasma membranes of purple bacteria . The minimal structural framework common to the mitochondrial and the bacterial complex is composed of 14 polypeptides with 1 FMN and 6-8 iron-sulfur clusters as prosthetic groups . The mitochondrial complex contains many accessory subunits for which no homologous counterparts exist in the bacterial complex . Genes for 11 of the 14 minimal subunits are also found in the plastidial DNA of plants and in the genome of cyanobacteria . However, genes encoding the 3 subunits of the NADH dehydrogenase part of complex I are apparently missing in these species . The possibility is discussed that chloroplasts and cyanobacteria contain a complex I equipped with a different electron input device . This complex may work as a NAD(P)H: or a ferredoxin:plastoquinone oxidoreductase participating in cyclic electron transport during photosynthesis.

Lancet, 1995 Jun 17, 345(8964), 1542 - 4
HLA-B27 binding of peptide from its own sequence and similar peptides from bacteria: implications for spondyloarthropathies; Scofield RH et al.; The spondyloarthropathies are associated by an unknown mechanism with HLA-B27 and certain bacteria . HLA-B27 shares sequence with proteins from enteric bacteria . The B*2705 sequence contains a nonapeptide, LRRYLENGK, predicted to bind in the binding cleft of B27 . Some nonapeptides from enteric organisms that share sequence with this nonapeptide of B27 also bind B27 . These observations suggest an unappreciated mechanism for autoimmunity that may operate in the B27-associated spondyloarthropathies involving peptides bound to and derived from histocompatibility alleles.

Gene, 1995 Jun 9, 158(2), 241 - 6
Production of active mouse DNA polymerase delta in bacteria; Hindges R et al.; The entire cDNA encoding the large subunit of mouse DNA polymerase delta (mPol delta; EC 2.7.7.7) has been cloned and expressed in various bacterial expression systems . A soluble protein could only be obtained when mPol delta was produced as a glutathione S-transferase (GST) fusion protein and the incubation temperature of the expression strain was reduced to 30 degrees C . After purification over a glutathione-Sepharose column, the fractions containing the recombinant (re-) fusion protein showed both DNA Pol and 3'-->5' Exo activities . In situ activity gel analysis indicated that the Pol activity resides in the re-protein . This activity, however, was not stimulated by proliferating cell nuclear antigen (PCNA) . Our data are discussed in the view of the findings of Goulian et al . {J . Biol . Chem., 265 (1990) 16402-16411} that the second mPol delta subunit, the 48-kDa protein, might play an important role in DNA Pol delta-PCNA interaction.

Environ Health Perspect, 1995 Jun, 103 Suppl 5, 29 - 32
Genetic adaptation of bacteria to halogenated aliphatic compounds; Janssen DB et al.; The bacterial degradation and detoxification of chlorinated xenobiotic compounds requires the production of enzymes that are capable of recognizing and converting compounds which do not occur at significant concentrations in nature . We have studied the catabolic route of 1,2-dichloroethane as an example of a pathway for the conversion of such a synthetic compound . In strains of Xanthobacter and Ancylobacter that have been isolated on 1,2-dichloroethane, the first catabolic step is catalyzed by a hydrolytic haloalkane dehalogenase . The enzyme converts 1,2-dichloroethane to 2-chloroethanol but is also active with many other environmentally important haloalkanes such as methylchloride, methylbromide, 1,2-dibromoethane, epichlorohydrin, and 1,3-dichloropropene . Further degradation of 2-chloroethanol proceeds by oxidation to the carboxylic acid and dehalogenation to glycolate . The aldehyde dehydrogenase prevents toxicity of the reactive chloroacetaldehyde that is formed as an intermediate and is necessary for establishing a functional 2-chloroethanol degradative pathway in a strain that is not capable of growth on this compound.

Genetika, 1995 Jun, 31(6), 741 - 52
{Genomic structure of bacteria: uniformity or diversity?}; Prozorov AA; This paper is a survey of data, indicating that, in contrast to widely adopted ideas, bacterial chromosomes and plasmids are not only circular, but also linear . Moreover, certain bacteria contain at least two different chromosomes per cell . Examples of other unusual genome properties in certain representatives of bacteria are also considered.

Biosci Biotechnol Biochem, 1995 Jun, 59(6), 1154 - 6
Degradation of polyaromatic hydrocarbons by organic solvent-tolerant bacteria from deep sea; Abe A et al.; We isolated three organic solvent (OS)-tolerant bacterial strains DS-1051, DS-1902, and DS-313 from a depth of 1,168 m in Sagami Bay, Japan . These isolates were tolerant to various kinds of toxic OSs such as benzene, toluene, and p-xylene . They also could degrade polyaromatic hydrocarbons, naphthalene or biphenyl, in a medium-OS (9:1) two-liquid-phase system . Percentage degradation of polyaromatic hydrocarbons in OS by these strains were higher than those obtained from cultures in which substrates were in the medium without OS.

Mol Microbiol, 1995 Jun, 16(5), 835 - 45
Repair, refold, recycle: how bacteria can deal with spontaneous and environmental damage to proteins; Visick JE et al.; Proteins, like DNA, are subject to various forms of damage that can render them non-functional . Conformational changes and covalent chemical alterations occur spontaneously, and the rates of these reactions can be increased by environmental stresses such as heat, oxidative agents, or changes in pH or osmotic conditions . Although affected proteins can be replaced by de novo biosynthesis, cells--especially those subjected to stress or nutrient limitation--have developed mechanisms which can either restore damaged polypeptides to an active state or remove them . Such mechanisms can spare the biosynthetic capacity of the cell and ensure that the presence of non-functional molecules does not disrupt cell physiology . Three major mechanisms, which operate in bacteria as well as eukaryotic organisms, have been described . First, chaperones not only assist in proper de novo folding of proteins but also provide an important means of restoring activity to conformationally damaged proteins . Second, enzymatic 'repair' systems exist to directly reverse certain forms of protein damage, including proline isomerization, methionine oxidation and the formation of isoaspartyl residues . Finally, proteolysis provides a 'last-resort' means of dealing with abnormal proteins which cannot be repaired . Protein maintenance and repair may be of special importance for bacteria preparing to survive extended periods in stationary phase: both constitutive and induced mechanisms are utilized to permit survival despite greatly reduced protein synthesis.

J Biol Chem, 1995 May 5, 270(18), 10847 - 54
Reconstitution of neuronal Cdc2-like kinase from bacteria-expressed Cdk5 and an active fragment of the brain-specific activator . Kinase activation in the absence of Cdk5 phosphorylation; Qi Z et al.; Neuronal Cdc2-like kinase is a heterodimer of Cdk5 and a 25-kDa subunit which is derived from a brain-specific 35-kDa novel protein, p35 (Lew, J., Huang, Q.-Q., Qi, Z., Winkfein, R . J., Aebersold, R., Hunt, T., and Wang, J . H . (1994) Nature 371, 423-426) . Three truncated forms of p35 including the one corresponding to the 25-kDa subunit of the kinase have been expressed in Escherichia coli and shown to activate a bacteria-expressed Cdk5 with equal efficacy . The shortest truncated form of p35, p21, spanning amino acid residues 88 to 291, has been used to reconstitute active Cdk5 kinase and to characterize the activation reaction . The purified kinase displays similar specific enzyme activity and similar phosphorylation site specificity as the neuronal Cdc2-like kinase purified from bovine brain . Bovine brain extract contains Cdk5 uncomplexed with p35 or p25 which has also been found to be activated by p21 or p25 . The results substantiate the previous suggestion that p35 is a specific Cdk5 activator . Several observations suggest that, unlike other well characterized Cdc2-like kinases whose activities depend on the phosphorylation of the catalytic subunits at a specific site by a distinct kinase, the reconstituted Cdk5/p21 does not depend on the phosphorylation of Cdk5 for activity . The reconstitution of the highly active Cdk5 kinase was achieved without requiring any other kinase in the reconstitution reaction . The possibility of autophosphorylation of Cdk5 on the putative activation site has been ruled out as no phosphorylation occurred on Cdk5 during the enzyme reaction . The rate and extent of the kinase reconstitution were not significantly affected by Mg2+ ATP.

Environ Res, 1995 May, 69(2), 122 - 31
Production of reactive oxygen metabolites by opsonized fungi and bacteria isolated from indoor air, and their interactions with soluble stimuli, fMLP or PMA; Ruotsalainen M et al.; Changes in the levels of free intracellular calcium ({Ca2+}i) and the production of reactive oxygen metabolites (ROM) induced by opsonized indoor air fungi and bacteria in human polymorphonuclear leukocytes (PMNL) were measured . Moreover, modification of a chemotactic peptide (fMLP)-and a tumor promoter (PMA)-induced production of ROM by opsonized fungi and bacteria were studied . The cells were exposed to graded doses of opsonized Candida sp., Aspergillus sp., Cladosporium sp., Stachybotrys sp., Penicillium sp., Paecilomyces sp., or A4 or A91 Streptomyces sp . alone, or together with fMLP or PMA . All the organisms were isolated from air samples of mold-problem buildings . None of the fungi or bacteria induced changes in {Ca2+}i or the production of ROM without opsonization with human serum . Of all opsonized fungi and bacteria, only Candida sp . elevated {Ca2+}i . All fungi and bacteria, except Paecilomyces sp . and Stachybotrys sp., markedly increased the production of ROM in PMNL . Furthermore, A91 Streptomyces sp . and Aspergillus sp . amplified fMLP-induced production of ROM . Only Candida sp . increased PMA-induced phenomen that normally occurs in the lung, was required for biological activity of the fungi and bacteria . Amplification by opsonization of fungi- or bacteria-induced leukocyte activation revealed remarkable changes between these biologically active particles . The present results suggest that many indoor air fungi and bacteria may activate leukocytes to produce oxidative stress, perhaps associated with harmful effects in exposed individuals.

Gaoxiong Yi Xue Ke Xue Za Zhi, 1995 May, 11(5), 265 - 73
{A study on sex hormones in gingival crevicular fluid and black pigmented bacteria in subgingival plaque of pregnant women}; Tsai CC et al.; Gingivitis is one of the most common oral diseases . It is caused by dental plaque and by the factors produced/released from it . The black pigmented bacteria in subgingival dental plaque are thought to be the periodontopathogens . Prevotella intermedia and Porphyromonas gingivalis have been shown to be closely associated with human gingivitis . Prevetella intermedia can use female sex hormones such as progesterone or estradiol as a source of nutrients . In pregnant women, the concentrations of progesterone and estradiol are markedly increased in serum and both are accumulated and found in the gingival tissue . The purpose of this study was to test levels of female sex hormones in gingival crevicular fluid and to observe the relationship between hormones and black pigmented bacteria in subgingival plaque . The results showed that the amount of progesterone found in the gingival crevicular fluid and percentage of black pigmented bacteria in subgingival plaque of pregnant women were markedly higher than in the postpartum stage . The percentage of black pigmented bacteria was positively correlated with the progesterone level, pregnancy and the severity of the gingivitis . Severity of the gingivitis was positively correlated with both the plaque index and the percentage of black pigmented bacteria in subgingival plaque.

J Immunol, 1995 May 1, 154(9), 4576 - 82
Retargeting of CTL by an efficiently refolded bispecific single-chain Fv dimer produced in bacteria; Kurucz I et al.; A single-chain bispecific Fv dimer (bs(sFv)2) having specificity for mouse CD3 epsilon chain and human transferrin receptor was produced in bacterial inclusion bodies . To overcome difficulties associated with in vitro protein folding, we used a novel renaturation approach to obtain active bs(sFv)2 . The protein was dissolved in the weak ionic detergent sodium lauroylsarcosine, and disulfides were formed by oxidation in air . After oxidation, the bs(sFv)2 exhibited very little covalent aggregation and migrated as a single species in nonreducing SDS-PAGE, suggesting that disulfides were correctly paired . The detergent was removed using an ion exchange resin and the protein fractionated by size exclusion chromatography . The recovered 65-kDa protein was monomeric in non-denaturing solvent, homogeneous by SDS-PAGE, and comprised 15 to 20% of material applied to the gel filtration column . This protein bound specifically to both mouse CD3 epsilon chain and human transferrin receptor with affinities indistinguishable from those of the parental Fabs or single-chain Fvs . The bs(sFv)2 specifically redirected mouse cytotoxic T cells to lyse target cells expressing human transferrin receptor at picomolar concentrations . Bacterially produced and detergent oxidized bs(sFv)2 molecules may therefore provide the abundant amounts of homogeneous active material required to redirect cytotoxic cells against tumors and other unwanted cells in animal models and in patients.

Proc Natl Acad Sci U S A, 1995 Apr 25, 92(9), 3958 - 62
Increased sensitivity to gamma irradiation in bacteria lacking protein HU; Boubrik F et al.; The heterodimeric HU protein, isolated from Escherichia coli, is associated with the bacterial nucleoid and shares some properties with both histones and HMG proteins . It is the prototype of small bacterial DNA binding proteins with a pleiotropic role in the cell . HU participates in several biological processes like cell division, initiation of DNA replication, transposition, and other biochemical functions . We show here that bacteria lacking HU are extremely sensitive to gamma irradiation . Expression of either one of the subunits of HU in the hupAB double mutant nearly restores the normal survival rate . This shows that the sensitivity is due to the absence of HU rather than being the result of a secondary mutation occurring in the hupAB cells or a modification of the SOS repair system, since SOS genes are induced normally in the absence of HU . Finally, in vitro studies give an indication of its potential role: HU protects DNA against cleavage by gamma-rays.

Vet Microbiol, 1995 Apr, 44(1), 1 - 9
Characterization of group EF-4 bacteria from the oral cavity of dogs; Ganiere JP et al.; Samples from gingival scrapings of dogs were examined for the presence of CDC Groups EF-4 bacteria . Isolation procedures were performed in 5% sheep blood agar supplemented with thiostrepton and trimethoprim (10 mg/l) . Fifty nine EF-4 strains were isolated from 92% of 49 dogs . Among the Group EF-4 bacteria, the majority of isolates belonged to the arginine-negative (biovar "b") Group EF-4 (42 strains recovered in 82% of dogs) . Seventeen arginine-positive strains (biovar "a") were recovered only from 35% of dogs . The strains were analysed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) . The analysis of electrophoretic protein pattern of these bacteria supported the results of conventional testing, confirmed the distinction between the biovars "a" and "b" of Group EF-4 and supported the division of biovar EF-4b into two subgroups of either producing or non-producing acid from gluconate.

FEMS Immunol Med Microbiol, 1995 Apr, 11(2), 137 - 44
Lipid A-associated proteins from periodontopathogenic bacteria induce interleukin-6 production by human gingival fibroblasts and monocytes; Reddi K et al.; The aim of this study was to determine whether lipid A-associated proteins (LAP) from two periodontopathogenic species of bacteria were able to stimulate interleukin-6 (IL-6) release from human gingival fibroblasts and myelomonocytic cells . LAP and lipopolysaccharide (LPS) were extracted from Porphyromonas gingivalis and Prevotella intermedia and added to cultures of human gingival fibroblasts and mono-mac-6 monocytic cells . Release of IL-6 into the culture supernatants was determined by ELISA . LAP and LPS from Por . gingivalis, but not from Prev . intermedia, stimulated IL-6 release from both cell types in a dose-dependent manner although LPS was less potent than LAP in inducing IL-6 release from the fibroblasts . IL-6 was detectable in cultures of both cell types following stimulation with LAP from Por . gingivalis at a concentration as low as 10 ng/ml . In response to LAP from Prev . intermedia, IL-6 was produced by mono-mac-6 cells but not by fibroblasts . Our results show that bacterial cell wall components other than LPS can induce IL-6 release from cells of the periodontium in vitro . The production of such potent immunomodulatory agents in vivo may contribute to the connective tissue breakdown characteristic of chronic periodontitis.

Biochem Mol Biol Int, 1995 Apr, 35(4), 833 - 40
New concept of energy migration and trapping in purple bacteria . Charge transfer-polaron model; Borisov AYu; A new hypothetical concept of the reaction center (RC) and the core BChl antenna is developed which claims to fit all up to date experimental data . In particular, the concept accounts for a number of findings still waiting for an explanation: a) the "red" shifts of the core BChl absorption peaks relative to those in their corresponding core BChls; b) the reason why in purple bacteria the second P2-P800-BPH-Q brunch of RC is inactive c) recent data parallel 1,2 on a small excitation portion which escapes from the excited RC special pair back to antenna BChls; d) why the primary electron donor is not monomer but a pair of parallel B Chls; e) the reason why the fluorescence spectra of the RC special pairs are enormously red-shifted relative to their absorption spectra.

Mol Reprod Dev, 1995 Apr, 40(4), 408 - 18
Induction of paternal genome loss by the paternal-sex-ratio chromosome and cytoplasmic incompatibility bacteria (Wolbachia): a comparative study of early embryonic events; Reed KM et al.; Paternal genome loss (PGL) during early embryogenesis is caused by two different genetic elements in the parasitoid wasp, Nasonia vitripennis . Paternal sex ratio (PSR) is a paternally inherited supernumerary chromosome that disrupts condensation of the paternal chromosomes by the first mitotic division of fertilized eggs . Bacteria belonging to the genus Wolbachia are present in Nasonia eggs and also disrupt paternal chromosome condensation in crosses between cytoplasmically incompatible strains . Cytoplasmic incompatibility Wolbachia are widespread in insects, whereas PSR is specific to this wasp . PGL results in production of male progeny in Nasonia due to haplodiploid sex determination . The cytological events associated with PGL induced by the PSR chromosome and by Wolbachia were compared by fluorescent light microscopy using the fluorochrome Hoescht 33258 . Cytological examination of eggs fertilized with PSR-bearing sperm revealed that a dense paternal chromatin mass forms prior to the first metaphase . Quantification of chromatin by epifluorescence indicates that this mass does undergo replication along with the maternal chromatin prior to the first mitotic division but does not replicate during later mitotic cycles . Contrary to previous reports using other staining methods, the paternal chromatin mass remains condensed during interphase and persists over subsequent mitotic cycles, at least until formation of the syncytial blastoderm and cellularization, at which time it remains near the center of the egg with the yolk nuclei . Wolbachia-induced PGL shows several marked differences . Most notable is that the paternal chromatin mass is more diffuse and tends to be fragmented during the first mitotic division, with portions becoming associated with the daughter nuclei . Nuclei containing portions of the paternal chromatin mass appear to be delayed in subsequent mitotic divisions relative to nuclei free of paternal chromatin . Crosses combining incompatibility with PSR were cytologically similar to Wolbachia-induced PGL, although shearing of the paternal chromatin mass was reduced . Wolbachia may, therefore, block an earlier stage of paternal chromatin processing in the fertilized eggs than does PSR.

Zhonghua Wai Ke Za Zhi, 1995 Apr, 33(4), 217 - 8
{The effect of platelet-activating factor antagonists on early bacteria translocation of rat after burn injury}; Qin X et al.; 30% third degree burn model of Wistar rat was used in this experiment . The animals were divided randomly into three groups (normal control, burn, and platelet-activating factor antagonist treatment) . After poured E . coli which labelled with acridine orange into intestine, the rats were killed at 6, 12, 24, and 48 hrs postburn, the bacteria in mesentery lymph node (MLN), liver and pulmonary organisms were cultured and counted, also observed by fluorescent microscopy directly . The results showed that, in PAF antagonist (WEB2170) treatment group, the quantity of bacteria in MLN, liver and lung were decreased significantly (P < 0.001) . The labelled bacteria in MLN, liver and lung of burn group were 100%, 80.0%, and 50.0% respectively compared with 40.0%, 30.0%, and 20.0% in treatment group . It is suggested that WEB 2170 could protect the intestine from bacteria translocation after burn injury.

Appl Environ Microbiol, 1995 Mar, 61(3), 985 - 91
Development and testing of improved suicide functions for biological containment of bacteria; Knudsen S et al.; We have developed very efficient suicide functions for biological containment based on the lethal Escherichia coli relF gene . The suicide functions are placed in duplicate within a plasmid and arranged to prevent inactivation by deletion, recombination, and insertional inactivation . The efficiency of this concept was tested in a plasmid containment system that prevents transfer of plasmids to wild-type bacteria . Protection against plasmid transfer was assayed in test tubes and in rat intestine . Protection was efficient and refractory to inactivation by mutation and transposons . The efficiency of the suicide system was also tested in soil and seawater . We show that unprecedented suicide efficiency can be achieved in soil and seawater after suicide induction by IPTG (isopropyl-beta-D-thiogalactopyranoside) . More than 7 orders of magnitude reduction in suicide bacteria was achieved.

Antimicrob Agents Chemother, 1995 Mar, 39(3), 620 - 5
Comparative complement selection in bacteria enables screening for lead compounds targeted to a purine salvage enzyme of parasites; Eakin AE et al.; Expression plasmids encoding the hypoxanthine phosphoribosyltransferases (HPRTs) of Plasmodium falciparum, Schistosoma mansoni, Tritrichomonas foetus, and Homo sapiens were subcloned into genetically deficient Escherichia coli that requires complementation by the activity of a recombinant HPRT for growth on semidefined medium . Fifty-nine purine analogs were screened for their abilities to inhibit the growth of these bacteria . Several compounds that selectively altered the growth of the bacteria complemented by the malarial, schistosomal, or tritrichomonal HPRT compared with the growth of bacteria expressing the human enzyme were identified . These results demonstrate that the recombinant approach to screening compounds by complement selection in a comparative manner provides a rapid and efficient method for the identification of new lead compounds selectively targeted to the purine salvage enzymes of parasites.

Biophys J, 1995 Mar, 68(3), 1089 - 100
Exciton dynamics in circular aggregates: application to antenna of photosynthetic purple bacteria; Novoderezhkin VI et al.; A theoretical model of exciton dynamics in circular molecular aggregates of light-harvesting bacteriochlorophyll of photosynthetic bacteria is proposed . The spectra and anisotropy of photoinduced absorption changes in the femto- and picosecond time domain are under its scope . The excited state of aggregate was treated due to the standard exciton theory, taking into account a pigment inhomogeneity . Dephasing processes via the exciton-phonon interactions were described by means of the Haken-Strobl equation . It was shown that only two exciton levels are dipole-allowed in the case of homogeneous circular aggregate . The pigment inhomogeneity results in the appearance of several weak transitions to higher exciton levels . It was proposed that the minor band (B896) in an absorption spectrum of the B875 complex as well as the similar minor band in spectra of B800-850 complex correspond to electron transition from the ground to the lowest exciton level, whereas the major band corresponds to transition to the higher exciton level . The proposed model shows the subpicosecond decay of anisotropy at the short-wavelength side of absorption band and a high degree of anisotropy at the long-wavelength side, even at high temperatures.

Can J Microbiol, 1995 Mar, 41(3), 235 - 40
Genetic diversity of N2-fixing bacteria associated with rice roots by molecular evolutionary analysis of a nifD library; Ueda T et al.; The rhizosphere of wetland rice has significant N2-fixing activity . It has been suggested that N2 fixation in the rice root zone is associated with the activity of various N2-fixing heterotrophic bacteria that inhabit the rice rhizosphere . Because of the generic diversity, many different isolation media and conditions are required to count and isolate these bacteria . In an attempt to overcome any bias from culture-dependent methods we amplified nifD segments from crude rice root DNA by the polymerase chain reaction . The nifD fragments were then cloned into a pT7 Blue T-vector to construct a nifD library . Sixteen cloned nifD genes chosen at random from the library were sequenced . A comparison with published sequences indicated the presence of seven novel groups of NifD proteins, which implies the existence of at least seven components in the diazotrophic community of rice roots, dominated mainly by proteobacteria . We also observed genetic variability within the clusters, which suggests the coexistence of many closely related bacterial lineages . However, we did not find Azospirillum-like nifD clones, although many reports indicated the widespread presence of Azospirillum spp . Therefore, it remains to be clarified whether Azospirillum species are the widespread N2-fixing bacteria in rice roots.

Eur J Biochem, 1995 Mar 1, 228(2), 297 - 304
Primary structure of the neuronal clathrin-associated protein auxilin and its expression in bacteria; Schroder S et al.; The protein auxilin is a coat component of brain clathrin-coated vesicles . It interacts directly with the heavy chain of clathrin and supports its assembly into regular cages {Ahle, S . & Ungewickell, E . (1990) J . Cell Biol . 111, 19-29} . The combined open reading frames of three cow brain cDNA clones with a total of 4531 nucleotides predict a molecular mass of 99,504 Da for auxilin . The coding region is followed by a very long untranslated region of at least 1670 nucleotides . By Northern analysis, auxilin transcripts are found only in brain tissue . Auxilin is not related to any of the previously sequenced clathrin-binding proteins, but the region of positions 50-350 is 29% identical (similarity 56%) to the corresponding region of the actin-binding protein tensin from chicken fibroblasts . Recombinant auxilin expressed in and purified from bacteria by affinity chromatography is functional with respect to clathrin binding.

Oral Dis, 1995 Mar, 1(1), 26 - 31
Comparison of the osteolytic activity of surface-associated proteins of bacteria implicated in periodontal disease; Reddi K et al.; OBJECTIVES: To compare the osteolytic activity of surface-associated material (SAM) and lipid A-associated proteins (LAPs) from periodontopathogenic bacteria . MATERIALS AND METHODS: Surface-associated material was extracted from the surface and LAPs from the cell walls of a range of periodontopathic bacteria including Actinobacillus actinomycetemcomitans and Eikenella corrodens . These bacterial fractions were assayed to determine their composition and their capacity to induce bone resorption was determined by use of the neonatal murine calvarial bone resorption assay . RESULTS: The SAMs from E . corrodens and A . actinomycetemcomitans demonstrated bone-resorbing capacity at concentrations as low as 1 ng ml-1 which, given the molecular weights of the active components, is in the picomolar range of activity . In contrast, the SAMs from the other three bacteria were significantly less potent and showed a lower efficacy . The LAPs all showed significant, and similar, capacities to induce bone breakdown . CONCLUSIONS: This is the first demonstration that LAP from periodontopathic bacteria can stimulate bone degradation . The LAPs from diverse bacteria all produced similar levels of bone-resorbing activity . In contrast, the SAM showed significant differences in potency and in efficacy (maximal stimulation) . This may mean that in vivo certain periodontopathic bacteria have significantly more bone-resorbing capacity than others and should be therapeutic targets.

J Appl Bacteriol, 1995 Mar, 78(3), 309 - 15
The ability of membrane potential dyes and calcafluor white to distinguish between viable and non-viable bacteria; Mason DJ et al.; Various dyes were assessed for their ability to discriminate between viable and non-viable bacteria . Two methods of killing were employed: by heat treatment or by gramicidin treatment . Staining was carried out in two ways; by staining directly in the medium or by washing cells prior to staining in buffer . Carbocyanine and rhodamine 123 dyes only exhibited small changes in fluorescence between viable and non-viable populations of bacteria . Both oxonol dye (bis 1,3-dibutylbarbituric acid trimethine oxonol) and calcafluor white proved much more useful.

Cell, 1995 Feb 24, 80(4), 603 - 9
Cloning of a novel bacteria-binding receptor structurally related to scavenger receptors and expressed in a subset of macrophages; Elomaa O et al.; A novel murine plasma membrane protein has been identified in subpopulations of macrophages . It has an intracellular N-terminal domain, a transmembrane domain, and an extracellular region with a short spacer, an 89 Gly-Xaa-Yaa repeat-containing collagenous domain, and a C-terminal cysteine-rich domain . In situ hybridization and immunohistochemical staining have localized the protein to a subset of macrophages in the marginal zone of the spleen and the medullary cord of lymph nodes . No expression was observed in macrophages of liver or lung . Transfected COS cells synthesized a native trimeric plasma membrane protein that bound labeled bacteria and acetylated LDL, but not yeast or Ficoll . The results suggest that the novel protein is a macrophage-specific membrane receptor with a role in host defense, as it shows postnatal expression in macrophages, which are considered responsible for the binding of bacterial antigens and phagocytosis.

Cell, 1995 Feb 10, 80(3), 507 - 15
Interspecies gene exchange in bacteria: the role of SOS and mismatch repair systems in evolution of species; Matic I et al.; Analysis of interspecies matings between S . typhimurium and E . coli indicates that the genetic barrier that separates these (and perhaps many other) related species is primarily recombinational . The structural component of this barrier is genomic sequence divergence . The mismatch repair enzymes act as potent inhibitors of interspecies recombination, whereas the SOS system acts as an inducible positive regulator . Interspecies mating triggers a RecBC-dependent SOS response in female bacteria that increases recombination mainly through overproduction of the RecA protein . Mismatch repair acts to reduce the mutation rate and recombination between similar sequences, whereas SOS acts to increase both . These opposing activities allow mismatch repair and SOS systems to determine both the rate of accumulation of sequence divergence and the extent of genetic isolation, which are the key components of the speciation process.

Biochemistry, 1995 Feb 7, 34(5), 1559 - 74
Enzymatic and chemical cleavage of the core light-harvesting polypeptides of photosynthetic bacteria: determination of the minimal polypeptide size and structure required for subunit and light-harvesting complex formation; Meadows KA et al.; To ascertain the minimal structural requirements for formation of the subunit and core light-harvesting complex (LH1), the alpha- and beta-polypeptides of the LH1 from three purple photosynthetic bacteria were enzymatically or chemically truncated or modified . These polypeptides were then used in reconstitution experiments with bacteriochlorophyll a (BChla), and the formation of subunit and LH1 complexes was evaluated using absorbance and circular dichroism spectroscopies . Truncation or modification outside of the conserved core sequence region of the polypeptides had no effect on subunit or LH1 formation . However, the extent of formation and stability of the subunit and LH1 decreased as the polypeptide was shortened inside the core region within the N-terminal domain . This behavior was suggested to be due to the loss of potential ion-pairing and/or hydrogen-bonding interactions between the polypeptides . While the spectroscopic properties of the subunit complexes generated using truncated polypeptides were analogous to those obtained using native polypeptides, in some cases the resulting LH1 complex absorption was blue-shifted relative to the control . Thus, truncation within the N-terminal domain may have long-range effects on the immediate BChla binding environment, since the putative BChla binding site resides near the C-terminal end of the polypeptides . It was also demonstrated that the His located within the membrane-spanning domain on the N-terminal end of the beta-polypeptide is not participating in ligation of the BChla in the reconstituted subunit and therefore probably not in LH1.

Mutat Res, 1995 Feb, 346(2), 77 - 84
Mathematical parameters for quantification of mutational responses in bacteria; Roldan-Arjona T et al.; This paper introduces a new parameter, derivable from dose-response data for induced mutagenesis in bacteria, that can be used to quantify mutational responses in short-term tests . We called this parameter the mutational response of the bipartite experimental system (agent plus cells) . We defined it as being jointly proportional to the efficiency of the mutagen and the sensitivity of the test . We show how this quantity can be used to rank order chemical carcinogens on the basis of their mutagenicity and to determine the strength of any quantitative correlation that may exist between mutagenicity in bacteria and carcinogenicity in rodents . We find that this particular measure of mutational response for 10 direct-acting monofunctional alkylating agents correlates remarkably well with the rodent carcinogenicity of these chemicals measured in terms of their reciprocal TD50 values.

Am J Gastroenterol, 1995 Feb, 90(2), 307 - 9
Acute gastritis associated with infection of large spiral-shaped bacteria; Yang H et al.; We report a case of gastric colonization of large spiral-shaped bacteria in a patient with acute gastritis . Endoscopy showed an acute erosive and hemorrhagic gastroduodenitis . Histopathological examination of antral biopsies revealed intense neutrophil infiltrates with microabscesses . Numerous large spiral-shaped bacteria were seen in the Gram-stained smear of the gastric biopsy . The patient was treated with colloidal bismuth subcitrate and cimetidine . Biopsy taken after treatment showed resolution of infection and histological gastritis . The results provide further evidence that large spiral-shaped bacteria are another infective cause of acute neutrophilic gastritis in humans.

Radiat Res, 1995 Feb, 141(2), 199 - 207
Interpretation of mutation induction by accelerated heavy ions in bacteria; Kozubek S et al.; In this report, a quantitative interpretation of mutation induction cross sections by heavy charged particles in bacterial cells is presented . The approach is based on the calculation of the fraction of energy deposited by indirect hits in the sensitive structure . In these events the particle does not pass through the sensitive volume, but this region is hit by delta rays . Four track structure models, developed by Katz (in Quantitative Mathematical Models in Radiation Biology, pp . 57-83, Springer-Verlag, 1988) . Chatterjee et al . (Radiat . Res . 54, 479-494, 1973), Kiefer and Straaten (Phys . Med . Biol . 31, 1201-1209, 1982) and Kudryashov et al . (Proceedings of the First Soviet Congress on Microdosimetry, Atomizdat, Moscow, 1973), respectively, were used for the calculations . With the latter two models, very good agreement of the calculations with experimental results on mutagenesis in bacteria was obtained . Depending on the linear energy transfer (LET infinity) of the particles, two different modes of mutagenic action of heavy ions are distinguished: "delta-ray mutagenesis," which is related to those radiation qualities that preferentially kill the cells in direct hits (LET infinity > or = 100 keV/microns), and "track core mutagenesis," which arises from direct hits and is observed for lighter ions or ions with high energy (LET infinity < or = 100 keV/microns).

J Virol, 1995 Feb, 69(2), 1093 - 8
Efficient in vivo and in vitro assembly of retroviral capsids from Gag precursor proteins expressed in bacteria; Klikova M et al.; The capsid precursor protein (Gag) of Mason-Pfizer monkey virus, the prototype type D retrovirus, has been expressed to high levels in bacteria under the control of the phage T7 promoter . Electron microscopic studies of induced cells revealed the assembly of capsid-like structures within inclusion bodies that formed at the poles of the cells 6 h after induction with isopropyl-beta-D-thiogalactopyranoside (IPTG) . The inclusion bodies and enclosed capsid-like structures were solubilized completely in 8 M urea, but following renaturation, we observed assembly in vitro of capsid-like structures that demonstrated apparent icosahedral symmetry . These results demonstrate for the first time that retroviral capsid precursors have the propensity to self-assemble in vitro and point to new approaches for the analysis of retroviral assembly and structure.

Glycoconj J, 1995 Feb, 12(1), 22 - 35
Lectins and also bacteria modify the glycosylation of gut surface receptors in the rat; Pusztai A et al.; Oral exposure to lectins or the presence or absence of bacteria in the rat small intestine were shown by histological methods using anti-lectin antibodies or digoxigenin-labelled lectins to have major effects on the state of glycosylation of lumenal membranes and cytoplasmic glycoconjugates of epithelial cells . Taken together with the dramatic effects of exposure to lectins on gut function, metabolism and bacterial ecology, this can be used as a basis for new perspectives of biomedical manipulations to improve health.

Biochemistry, 1995 Jan 17, 34(2), 517 - 23
Structure and properties of the bacteriochlorophyll binding site in peripheral light-harvesting complexes of purple bacteria; Sturgis JN et al.; In this paper, we have examined, using FT resonance Raman spectroscopy, the bacteriochlorophyll (BChl) binding sites in the peripheral light-harvesting complexes extracted from a number of purple bacterial strains . A comparison of interactions of the BChl molecules with their binding sites in these LH2 complexes, together with the primary sequences of the alpha and beta polypeptides, allows three amino acids to be proposed to be involved in the hydrogen bonding of the 9-keto carbonyl of one of the 850-nm-absorbing pair of BChl molecules . Specifically, we show that one keto carbonyl group, which is strongly hydrogen bonded in Rhodobacter sphaeroides LH2, is involved in much weaker interactions in the LH2 complexes from all the other species studied (i.e., Rhodobacter capsulatus, Rubrivivax gelatinosus, Rhodopseudomonas palustris, Rhodopseudomonas acidophila, and Rhodopseudomonas cryptolactis) . This is correlated with the presence of three polar amino acids in the primary sequence of the alpha polypeptide of Rb . sphaeroides which are absent in the sequences from all the other bacteria and probably close to a chromophore . These three residues are a serine at position -4, a threonine at position +6 and another serine at position +17 (numbering relative to the conserved histidine, considered as position 0), in the alpha polypeptide of Rb . sphaeroides . Furthermore, the study of the interactions in natural B800-820 complexes shows that the two 2-acetyl groups of the 820-nm-absorbing BChl molecules are free from hydrogen-bonding interactions . In the light of previous site-selected mutagenesis studies, the lack of such hydrogen bonds seems to be a general phenomenon, associated with the 820-nm absorption of LH2 complexes, and suggests that hydrogen-bonding interactions have a precise molecular role in finely tuning the functional properties of these complexes.

Presse Med, 1995 Jan 14, 24(2), 129 - 32
{Defense mechanisms against bacteria of intracellular development}; Nauciel C; Intracellular bacteria are not inhibited by antibodies . Therefore the main mechanisms of resistance against these pathogens are the influx and activation of mononuclear phagocytes by the synergistic interaction of gamma-interferon and tumour necrosis factor . During the early phase of infection, gamma-interferon is produced by IL-12-activated natural killer cells (IL-12 being mainly produced by macrophages) . In the later phase of infection acquired immunity is T-cell-mediated and involves the Th1 CD4+ subpopulation . These cells produce gamma-interferon when triggered by antigen . There is a complex network of interactions among cytokines . Some cytokines act synergistically to enhance resistance to infection, yet antagonistic interactions can sometimes occur.

FEBS Lett, 1995 Jan 2, 357(1), 16 - 8
Phosphate regulation of biosynthesis of extracellular RNases of endospore-forming bacteria; Znamenskaya LV et al.; The gene for the extracellular ribonuclease of B . pumilus KMM62 (RNase Bp) has been cloned and sequenced . The structural gene for this enzyme is similar to those of the extracellular ribonucleases of B . intermedius 7P (binase) and B . amyloliquefaciens H2 (barnase), as are the regulatory regions of binase and RNase Bp . The regulatory region of the barnase gene, however, is quite different from the other two . In the promoter of the genes for binase and RNase Bp, but not in that for barnase, is a region similar to the Pho box of E . coli . We have established that inorganic phosphate suppresses the synthesis of the binase and RNase Bp, but does not effect the synthesis of barnase.

Mol Biol Rep, 1995-96, 22(2-3), 99 - 109
RNase P from bacteria . Substrate recognition and function of the protein subunit; Kirsebom LA et al.; RNase P recognizes many different precursor tRNAs as well as other substrates and cleaves all of them accurately at the expected position . RNase P recognizes the tRNA structure of the precursor tRNA by a set of interactions between the catalytic RNA subunit and the T- and acceptor-stems mainly, although residues in the 5'-leader sequence as well as the 3'-terminal CCA are important . These conclusions have been reached by several studies on mutant precursor tRNAs as well as cross-linking studies between RNase P RNA and precursor tRNAs . The protein subunit of RNase P seems also to affect the way that the substrate is recognized as well as the range of substrates that can be used by RNase P, although the protein does not seem to interact directly with the substrates . The interaction between the protein and RNA subunits of RNase P has been extensively studied in vitro . The protein subunit sequence is not highly conserved among bacteria, however different proteins are functionally equivalent as heterologous reconstitution of the RNase P holoenzyme can be achieved in many cases.

Sci Prog, 1995, 78 ( Pt 4), 301 - 10
The cold-shock response in bacteria; Wolffe AP; The 'cold shock' response that occurs when exponentially growing Escherichia coli at 37 degrees C are transferred to 10 degrees C leads to the cesation of most protein synthesis, however, about 14 'cold shock' proteins continue to be made . These 'cold shock' proteins facilitate growth at low temperatures . Central to the regulation of this switch in gene expression is the 200 fold induction in the relative rate of synthesis of a small cold-shock protein only 70 amino acids in length, known as CS7.4 . There is a remarkable conservation through evolution of the primary sequence found in this small cold shock protein and that of a nucleic acid binding domain within the Y-box family of eukaryotic gene regulatory proteins . Parallel studies on CS7.4 and the Y-box proteins have elucidated both molecular mechanisms regulating the cold shock response and a novel site for the regulation of eukaryotic gene expression.

Nat Toxins, 1995, 3(6), 428 - 35
Enhancement of domoic acid production by reintroducing bacteria to axenic cultures of the diatom Pseudo-nitzschia multiseries; Bates SS et al.; Axenic cultures of Pseudo-nitzschia multiseries (formerly Pseudonitzschia pungens f . multiseries) produce less domoic acid (DA) than the original bacteria-containing cultures . Bacterial strains isolated from two nonaxenic P . multiseries clones were reintroduced individually into cultures of three axenic P . multiseries strains . The bacteria did not substantially affect division rates or cell yields . However, they did cause a 2- to 95-fold enhancement of DA production (per cell basis) relative to the axenic culture, depending on the P . multiseries and bacterial strain used . Bacteria isolated from a nontoxic Chaetoceros sp . culture also enhanced DA per cell (by 115-fold), showing that it is not necessary for the bacteria to be isolated from a toxic culture in order to enhance toxin production . There was no evidence of intracellular bacteria in disrupted P . multiseries cells obtained from axenic cultures . Our results demonstrate an important, but nonessential, role of extracellular bacterial in DA production . Characterization of the bacterial strains using morphology, substrate utilization, and restriction fragment length polymorphism (RFLP) analyses clearly showed that we had isolated different species of bacteria from the various nonaxenic cultures . We conclude that not one but several bacterial species enhance DA production by P . multiseries.

Scand J Gastroenterol Suppl, 1995, 212, 13 - 8
Bacteria in the aetio-pathogenesis of gastric cancer: a review; Houben GM et al.; Severe atrophic gastritis, a precursor lesion of gastric carcinoma, is connected, in two different ways, with intragastric bacterial colonization: (1) in advanced atrophic body gastritis (type A), achlorhydria or severe hypochlorhydria leads to bacterial overgrowth with aerobic and anaerobic flora enabling the conversion of nitrate to nitrite and further to N-nitroso compounds; (2) the newly re-discovered Helicobacter pylori is probably one of the major causes of chronic atrophic antral gastritis (type B) . Both types of bacteria may be involved in the pathogenesis of multifocal gastritis (type AB) . In the western world, achlorhydric atrophic gastritis is not only found in pernicious anaemia but is latent in about 2 to 6% of the general population . In one study from the Mayo Clinic, about one-third of consecutive gastric carcinomas were present in achlorhydric stomachs, the remainder in acid-secretors . Apart from the N-nitroso compounds, other carcinogenic mechanisms may be active in type A gastritis: elevated serum gastrin; altered cell turnover; immunologic and hereditary traits . The association of H . pylori with gastric carcinoma is mainly based on circumstantial evidence: (i) epidemiological studies indicate a moderately increased risk for gastric cancer in H . pylori-positive subjects compared with H . pylori-negative; (ii) in the presence of H . pylori intragastric levels of the anti-oxidant ascorbic acid are lowered; (iii) H . pylori seems to be linked to mucosal atrophy and intestinal metaplasia; (iv) recent follow-up studies show a significant development of atrophic gastritis in H . pylori-positive patients compared to H . pylori-negative.(ABSTRACT TRUNCATED AT 250 WORDS)

Int J Syst Bacteriol, 1995 Jan, 45(1), 57 - 60
Description of human-derived Centers for Disease Control coryneform group 2 bacteria as Actinomyces bernardiae sp . nov; Funke G et al.; Biochemical, chemotaxonomic, and molecular methods were used to establish the precise taxonomic position of the Centers for Disease Control (CDC) coryneform group 2 bacteria . The results of a comparative 16S rRNA sequence analysis demonstrated that the CDC coryneform group 2 bacteria constitute a distinct species within the genus Actinomyces . Actinomyces pyogenes was found to be the closest genealogical relative of the CDC coryneform group 2 bacteria, although these taxa were readily distinguished from each other and other Actinomyces spp . by using phenotypic criteria . On the basis of our findings we propose the name Actinomyces bernardiae sp . nov . for the CDC coryneform group 2 bacteria . The type strain is DSM 9152 (CCUG 33419).

Arch Surg, 1995 Jan, 130(1), 53 - 8
The effect of endotoxin on intestinal mucosal permeability to bacteria in vitro; Go LL et al.; OBJECTIVE: To examine the role of the intestinal mucosa in bacterial translocation, in vitro bacterial passage across ileal mucosal segments mounted in Ussing chambers were studied in control and endotoxin (lipopolysaccharide)-treated rats . DESIGN: Experimental study . MATERIALS AND METHODS: Three groups of rats were studied . The experimental group received an intraperitoneal injection of lipopolysaccharide, while controls received an equivalent volume of saline solution; a third group received no treatment . Twenty-four hours later, all groups underwent laparotomy and organ culture to assess bacterial translocation . At the same time, a segment of mucosa from the terminal ileum of each animal was mounted in a Ussing chamber, and the transmucosal passage of labeled Escherichia coli from the luminal to serosal surface was assessed by results of serial cultures . RESULTS: In vivo bacterial translocation occurred in 100% of the lipopolysaccharide-treated animals, significantly higher than the incidence seen in controls (25%; P < .05) . In vitro passage of labeled E coli across ileal mucosa in the Ussing chamber occurred in 78% of lipopolysaccharide-treated animals, while in controls transmucosal passage was seen in only 14% (P < .05) . Histologic examination of mucosa from both groups using light and transmission electron microscopy demonstrated no structural differences between groups . CONCLUSIONS: Increased permeability to bacteria at the mucosal level contributes to the bacterial translocation seen in endotoxemia.

Avian Dis, 1995 Jan-Mar, 39(1), 175 - 8
Intralesional herpesvirus, reovirus-like particles, and bacteria in a flock of broiler chicks with spiking mortality, diarrhea, and enterotyphlitis; Goodwin MA et al.; The search for a solitary cause of spiking mortality (so-called spiking mortality syndrome) among broiler chicks has been thwarted by the fact that multiple agents cause similar mortality histograms . In the present case report, we describe intralesional herpesvirus, reovirus-like virus particles, and bacteria in small and large intestines from chicks with a spiking mortality histogram, diarrhea, and enterotyphlitis . We attributed the spiking mortality histogram to starvation coupled with diarrhea.

J Biochem (Tokyo), 1995 Jan, 117(1), 216 - 21
Mouse macrophage metalloelastase expressed in bacteria absolutely requires zinc for activity; Jeng AY et al.; Mouse macrophage metalloelastase was expressed in Escherichia coli . This recombinant enzyme (rMME) was present in the inclusion bodies that were solubilized in 7 M guanidine HCl . After removal of guanidine HCl, rMME was purified with a Q-Sepharose column . Degradation of {3H}elastin by rMME absolutely required Ca2+; the optimal Ca2+ concentration was 5 mM . NaCl stimulated the enzyme activity; maximal stimulation was obtained at 400 mM . The rMME activity was inhibited by metalloprotease inhibitors, but not by serine, aspartyl, or thiol protease inhibitors . Among the divalent cations tested, only Ba2+ and Sr2+ exhibited marginal stimulation of rMME activity in the absence of Ca2+ . Cu2+, Zn2+, or Cd2+ strongly inhibited rMME activity with IC50 values between 68 and 180 microM, while Mg2+, Ba2+, Mn2+, Co2+, and Sr2+ had no effect . The requirement of Zn2+ for rMME activity was determined . Significant enzyme activity was present in rMME treated with EDTA followed by Q-Sepharose column chromatography . Only when the inclusion bodies were solubilized in the presence of 20 mM EDTA, did an enzyme preparation which was absolutely dependent on exogenous Zn2+ for activity result . The optimal Zn2+ concentration for rMME activation was 100 microM . These results indicate that Zn2+ is tightly bound to rMME.

Acta Otolaryngol, 1995 Jan, 115(1), 106 - 11
Imprints from the oropharyngeal mucosa: a novel method for studies of cell-kinetics and spatial relations between leukocytes, epithelial cells and bacteria in the secretion on the surface of the mucosa; Ebenfelt A et al.; Cell-kinetics and spatial relations between the cellular elements in the secretion on the mucosal surfaces of the oral cavity and the pharynx were studied with a new imprint technique whereby pieces of foam-plastic are pressed against the mucosal surfaces and then immediately against a glass slide . For visualisation of leukocytes, epithelial cells and bacteria, imprints were stained according to May Grunewald-Giemsa and with acridine orange . For visualisation and discrimination between T and B-cells, slides were stained with immunohistochemical technique using anti-CD-3 and anti-CD-19, respectively, as antibodies . Imprints were also prepared for scanning electron microscopy (SEM) . The results show that there are large numbers of morphologically intact cells in the secretions and that there are statistically significant differences between the different mucosal areas as regards numbers, types and spatial relations between the cellular elements in the surface secretions . Rather great inter- and intra-individual differences in cellular composition were observed, indicating a dynamic system . This was further documented by observation of a dominance of polymorphonuclear leukocytes on the tonsillar surface, in contrast to the dominance of mononuclear leukocytes in secretion from the mesopharynx . We consider that this new imprint method is reliable and gives representative samples from the surface secretion . The results clearly show the need for further studies concerning the physiological role of the cellular elements in the surface secretion of the oral cavity and mesopharynx.

FEMS Immunol Med Microbiol, 1995 Jan, 10(2), 101 - 8
Serum antibody response to surface-associated material from periodontopathogenic bacteria; Meghji S et al.; Saline extracts of Actinobacillus actinomycetemcomitans, Porphyromonas gingivalis and Eikenella corrodens contain surface-associated components of these bacteria . It has been shown that these extracts are potent stimulators of bone resorption in vitro . The possibility that the components of these surface-associated materials (SAM) could contribute to the serum immune response in patients with juvenile or adult onset forms of rapidly progressive periodontitis were investigated by direct binding ELISA . Very high titres of serum IgG antibodies to SAM from A . actinomycetemcomitans were detected in patients with localized juvenile periodontitis (LJP) . Patients with adult onset rapidly progressive periodontitis (RPP) had significantly raised antibody levels to SAM from P . gingivalis . Both groups of patients had significantly raised levels of antibodies to SAM from E . corrodens compared with control sera . Thus, not only does solubilized SAM have the capacity to induce bone resorption, but it also contributes to the antigenic load on the immune system in LJP and RPP.

Anal Biochem, 1995 Jan 1, 224(1), 390 - 4
Detection of glycoprotein receptors on blotting membranes by binding of live bacteria and amplification by growth; Karlsson A et al.; Conditions have been adapted for detecting bacteria bound to glycoprotein receptors on blotting membranes using a self-enhancing detection method based on bacterial growth . Neutrophil plasma membrane proteins, mediating adherence of mannose-binding type-1-fimbriated Escherichia coli and concanavalin A (Con A) to intact human neutrophils, were separated by SDS-PAGE and transferred onto a polyvinylidene difluoride (PVDF) membrane . The PVDF membrane was immersed in a suspension of mannose-binding type-1-fimbriated E . coli, and after repeated washings, bound bacteria were allowed to multiply into bacterial colonies by placing the membrane on a solid nutrient substratum . About one major and eight minor glycoproteins, some of which also were detected by Con A, selectively induced colony formation in a mannose-inhibitable fashion . Binding of {35S}methionine metabolically labeled E . coli to PVDF membranes produced a virtually identical binding pattern, demonstrating further the accuracy of this self-enhancing detection method which is rapid, simple, and sensitive and avoids radioisotopes.

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