Salmonella typhimurium

Mutat Res, 1992 Feb, 271(1), 89 - 96
Mutagenicity assay for nitroarenes of air pollutants held in leaves of woody plants; Suzuki J et al.; A new method was developed for the detection of mutagenic nitroarenes held in the leaves of woody plants using a small amount of leaves . This method consists of extraction of mutagen from fresh leaves (15-30 g) by ultrasonication with ethyl acetate and purification by elution with benzene on a silica gel column to remove such inhibitory components for mutagenesis as chlorophyll . The mutation assay uses the new Salmonella typhimurium strains YG1021 (a nitroreductase-overproducing strain of TA98) and YG1024 (an O-acetyltransferase-overproducing strain of TA98), which are very sensitive to some nitroarenes in the absence of S9, and standard strain YG1020 (TA98 containing pBR322-Aps) for comparison . This method was applied to woody plants growing on various sites in the Tokyo metropolitan area and the suburbs . It was shown that the leaves of all woody plants tested contained different amounts of mutagens, probably mutagenic nitroarenes, depending upon their growing sites.

Mutat Res, 1992 Feb, 271(1), 1 - 12
Collaborative study using the preincubation Salmonella typhimurium mutation assay for airborne particulate matter in Japan . A trial to minimize interlaboratory variation; Matsushita H et al.; A collaborative study has been performed over a period of 3 years to develop a suitable method for monitoring the mutagenicity of airborne particulate matter . The study was organized with 8 laboratories and performed in the following steps: (1) selection of a suitable technique for each process involved in the mutagenicity monitoring, (2) developing a tentative protocol by combining systematically the selected techniques, (3) evaluation of the protocol by intra- and inter-laboratory studies, (4) modification of the protocol according to the evaluation, and (5) evaluation of the modified protocol by conducting an interlaboratory study . We found a suitable method for mutagenicity monitoring of particles in the atmosphere . Airborne particles were sampled with a high-volume sampler, the samples were stored at -80 degrees C, extracted by sonication using dichloromethane, solvent-exchanged, and assayed by the preincubation method using Salmonella typhimurium TA98 and TA100 . The observed mutagenic activity was normalized with that of an internal standard . Round robin tests revealed that the method resulted in excellent reproducibility . The coefficient of variation for mutagenic activities of airborne particulate samples collected in various districts of Japan were in the range of 14.7 +/- 6.6% to 19.6 +/- 4.0% for strains TA98 and TA100 with and without metabolic activation . We also found that the plate incorporation method was equivalent to the preincubation method for airborne particulate extracts.

Mutat Res, 1992 Feb, 281(2), 143 - 7
Mutagenicity of pyrrolizidine alkaloids in the Salmonella typhimurium/mammalian microsome system; Rubiolo P et al.; The mutagenicity of a series of pyrrolizidine alkaloids, and of extracts from several Italian Senecio species containing pyrrolizidine alkaloids, including S . inaequidens, S . fuchsii and S . cacaliaster, were tested using the Salmonella typhimurium/mammalian microsome system . Retrorsine, senecivernine, seneciphylline and the Senecio extracts showed a weakly mutagenic activity.

Mutat Res, 1992 Feb, 265(2), 263 - 72
Formation of genotoxic metabolites from anthraquinone glycosides, present in Rubia tinctorum L; Blomeke B et al.; Rubia tinctorum L., a medicinal plant used for the treatment of kidney and bladder stones, contains a characteristic spectrum of 9,10-anthraquinone derivatives, which are substituted in only one of the aromatic benzo rings . The majority of the anthraquinones present in the plant itself or in plant extracts are glycosides . We investigated the metabolism of two such glycosides, alizarinprimeveroside (AlP) and lucidinprimeveroside (LuP) . AlP given orally to rats was metabolized to alizarin (Al) and 1-hydroxyanthraquinone (1-HA) . The reductive cleavage of AlP was also observed after treatment of this compound with rat liver enzymes (S9) and NADPH . 1-HA has been reported to induce unscheduled DNA synthesis (UDS) in primary rat hepatocytes (PRH) and intestinal and liver tumors in rats after chronic treatment . The in vitro genotoxicity of 1-HA was confirmed by our present investigations . We also observed that the glycoside AlP was active at inducing UDS in PRH, but the compound was inactive in the Salmonella/microsome assay . Oral administration of LuP to rats resulted in the excretion of lucidin and rubiadin . When LuP was treated with rat liver extract and NADPH, the compound was reduced to rubiadinprimeveroside (RuP), which was hydrolyzed to rubiadin . We have recently shown that lucidin is highly genotoxic in a battery of short-term tests . We now report that rubiadin is also highly genotoxic in Salmonella typhimurium . However, in contrast to lucidin, it requires metabolic activation . In the UDS assay in PRH, rubiadin was even more potent than lucidin and equal to the positive control DMBA . In addition, the glycoside LuP is active in the Salmonella/microsome assay as well as in the UDS assay . The present work demonstrates that the uptake of the anthraquinone glycosides AlP and LuP leads to the rodent carcinogen 1-HA, and to the highly genotoxic compounds lucidin and rubiadin . This extends our previous studies and supports our suggestion that the therapeutic use of Rubia tinctorum may involve a carcinogenic risk.

Mutat Res, 1992 Feb, 265(2), 181 - 93
Modulation of mutagenic properties in a series of DNA-directed alkylating agents by variation of chain length and alkylator reactivity; Ferguson LR et al.; Four series of aniline mustards linked to a DNA-affinic acridine chromophore by alkyl chains of varying length (2-5 carbon atoms) have been studied for their mutagenic properties, as estimated in four strains of Salmonella typhimurium and in Saccharomyces cerevisiae strain D5 . The four series have very different mustard reactivities, as determined by the aniline link group (-O-, -CH2-, -S- or -SO2-) . Some of the derived compounds cause frameshift mutagenesis which can be detected in TA98 and also "petite" mutagenesis activity, neither of which occur to significant extents with the parent mustards or with 9-aminoacridine . None of the derived compounds are as effective as the parent mustards in mitotic crossing-over, nor do they show ability for frameshift mutagenesis in S . typhimurium TA1977 which is typical of acridines . Some of the compounds have comparable frameshift activity to compounds such as ICR-191, but appear to have a different base-pair preference . The results indicate clear structure-activity relationships for the spectrum of mutagenic activity, which relate to both chain length and alkylator reactivity, for these compounds.

Mutat Res, 1992 Feb, 265(2), 149 - 54
Modulating effect of tanshinones on mutagenic activity of Trp-P-1 and benzo{a}pyrene in Salmonella typhimurium; Sato M et al.; The modulating effects of the Chinese medicinal plant 'Tan-shen', the radix of Salvia miltiorrhiza Bunge, on the mutagenic activities of Trp-P-1 (3-amino-1,4-dimethyl-5H-pyrido{4,3-b}indole) and B(a)P (benzo{a}pyrene) were investigated using Salmonella typhimurium TA98 . Ether- and hot water-extracted 'Tan-shen' enhanced both mutagens at low concentrations, but suppressed them at high concentrations . Extracts by ether treatment were more effective than those extracted by hot water . Dihydrotanshinone I, cryptotanshinone, tanshinone I, and tanshinone IIA were isolated from the ether extract by high performance liquid chromatography (HPLC) and were recognized to be the mutagenic modulators . 4 tanshinones enhanced the mutagenicity of Trp-P-1 by 8-24-fold at 20 micrograms/plate and the enhancement was reduced at the higher concentration . Dihydrotanshinone I suppressed Trp-P-1 activity completely at 100 micrograms/plate.

Infect Immun, 1992 Feb, 60(2), 491 - 6
Virulence of non-type 1-fimbriated and nonfimbriated nonflagellated Salmonella typhimurium mutants in murine typhoid fever; Lockman HA et al.; The virulence of Salmonella typhimurium mutants that were unable to synthesize type 1 fimbriae was tested in a murine typhoid fever model . Nonfimbriated mutants (fim) exhibited a lower 50% lethal dose than a wild-type (fim+) strain and produced significantly higher mortality (fim, 55%; fim+, 37% {P less than 0.002}) in mice that were challenged orally . There was no difference in virulence when the wild-type and mutant strains were injected intraperitoneally into mice . The progress of a short-term lethal infection was monitored after oral inoculation of mice with a mixture containing equivalent numbers of fim+ wild-type and fim mutant bacteria . The results indicated that while both strains colonized the intestinal tract equally well and invaded internal organs, the S . typhimurium fim mutant proliferated in the blood of the mice faster than the fim+ strain . The results of the mixed oral challenge suggested that bacteremia caused by fim+ S . typhimurium was reduced or delayed by the sequestration of the fimbriated bacteria in the spleen, liver, and kidneys . Thus, type 1 fimbriae were not virulence factors for S . typhimurium in this model, and the fimbriae may be an impediment to the pathogen in this setting . An S . typhimurium double mutant lacking type 1 fimbriae and flagella (fla) also was tested in mice . The virulence of the fim fla mutant was greatly reduced compared with that of the wild-type strain (mortality from fim fla challenge, 11% {P less than 0.0005}) . The significance of this latter result is discussed in relation to host adaptation by pathogenic salmonellae.

FEMS Microbiol Immunol, 1992 Feb, 4(3), 147 - 53
Detection of porin antigen in serum for early diagnosis of mouse infections with Salmonella typhimurium; Muthukkumar S et al.; The monoclonal antibodies to porin, an outer membrane protein isolated from Salmonella typhimurium and sandwich enzyme linked immunosorbent assay (ELISA) has made possible the detection of porin from sera of S . typhimurium-infected mice . The specificity of the monoclonal antibodies was ascertained based on their cross-reactivity with porins isolated from S . typhi, Shigella flexneri and Escherichia coli and lipopolysaccharide (LPS) of S . typhimurium and E . coli . Serum samples were found to be positive for porin as early as 3 days after intravenous and 5 days after oral infection . In addition, a positive correlation was observed between the bacterial load and the concentration of porin detected in the sera . On the other hand, analysis of sera for anti-porin antibody showed diametrically opposite time kinetics with antigenaemia . These results indicate that porin accumulates in the serum of infected mice much earlier than the appearance of antibodies to porin . Thus detection of porin holds promise for early diagnosis of typhoid.

Gene, 1992 Feb 1, 111(1), 43 - 9
Localization of the exonuclease and polymerase domains of Bacillus subtilis DNA polymerase III; Barnes MH et al.; Structural gene mutants were cloned and exploited to identify the major catalytic domains of Bacillus subtilis DNA polymerase III (BsPolIII), a 162.4-kDa {1437 amino acids (aa)} polymerase: 3'-5' exonuclease (Exo) required for replicative DNA synthesis . Analysis of the sequence, mutagenicity, and catalytic behavior of natural and site-directed point mutants of BsPolIII unequivocally located the domain involved in exonuclease catalysis within a 155-aa residue segment displaying homology with the Exo domain of Escherichia coli DNA polymerase I . Sequence analysis of four structural gene mutations which specifically alter then enzyme's reactivity to the inhibitory dGTP analog, 6-(p-hydroxyphenylhydrazino)uracil, and the inhibitory arabinonucleotide, araCTP, defined a domain (Pol) involved in dNTP binding . The Pol domain was in the C-terminal fourth of the enzyme within a 98-aa segment spanning aa 1175-1273 . The primary structure of the domain was unique, displaying no obvious conservation in any other DNA polymerase, including the distantly related PolIIIs of the Gram- organisms, E . coli and Salmonella typhimurium.

Sci Total Environ, 1992 Jan 15, 111(2-3), 109 - 24
Analysis of the genotoxicity of municipal solid waste incinerator ash; Silkowski MA et al.; Combined bottom and fly ash obtained from a Chicago, IL, municipal solid waste incinerator (MSWI) was extracted with organic solvents, water or acidified water . The mean amounts of organic material isolated from each extraction procedure were 688.2, 91.8 and 167.7 micrograms/g MSWI ash . These extracts were evaluated for toxicity and mutagenicity in Salmonella typhimurium strains TA98 and TA100 . We developed and calibrated a micropreincubation assay to evaluate small concentrations of the organic extracts . No direct-acting mutagens were found, however the acid-treated aqueous extracts were toxic . Materials isolated with methylene chloride methanol were mutagenic after hepatic microsomal activation (S9) . The mutagenic potencies of the organic extract normalized to a per gram ash basis was the induction of 103.46 revertants in TA98 and 247.5 revertants in TA100 . The aqueous extracts were neither toxic nor mutagenic . However, the acid-treated aqueous extract was mutagenic to TA100 . The organic material isolated from the acidic extract had an induced mutagenic potency of 44.2 revertants/mg extract . Normalizing these data indicate a mutagenic potency of 7.4 revertants/g MSWI ash leached.

Cancer Lett, 1992 Jan 10, 61(2), 129 - 34
The effect of ellagic acid on xenobiotic metabolism by cytochrome P-450IIE1 and nitrosodimethylamine mutagenicity; Wilson T et al.; Ellagic acid (EA) is an inhibitor of the in vitro mutagenicity of N-nitrosodimethylamine (NDMA) in Salmonella typhimurium strain TA100 using pyrazole-induced rat liver 9000 x g supernatant (S-9) . In order to understand this activity, the effect of EA on the metabolic hydroxylation of 4-nitrophenol, a substrate, as is NDMA, for cytochrome P-450IIE1 was studied using pyrazole induced rat S-9 and microsomal protein . It is shown that EA has an inhibitory effect on 4-nitrophenol hydroxylase with both enzyme preparations . This effect on cytochrome P-450IIE1 may be responsible, at least in part, for the inhibition of NDMA mutagenicity by EA.

Biochim Biophys Acta, 1992 Jan 6, 1129(2), 228 - 30
The nucleotide sequence of leuB from Salmonella typhimurium; Andreadis A et al.; The nucleotide sequence and deduced polypeptide sequence of the Salmonella typhimurium leuB are reported, as well as a conserved region that might bind the enzyme substrate.

Biochim Biophys Acta, 1992 Jan 6, 1129(2), 223 - 7
Completion of the nucleotide sequence of the 'maltose B' region in Salmonella typhimurium: the high conservation of the malM gene suggests a selected physiological role for its product; Schneider E et al.; We have subcloned and sequenced the genes malF and malM of Salmonella typhimurium, thereby completing the determination of the nucleotide sequence of its 'maltose B' regulon . The malM gene, encoding a periplasmic protein of unknown function in Escherichia coli, is a highly conserved as genes encoding proteins of known function from the same region.

J Mol Biol, 1992 Jan 5, 223(1), 171 - 84
Substructure of the flagellar basal body of Salmonella typhimurium; Sosinsky GE et al.; The Salmonella typhimurium basal body, a part of the flagellar rotary motor, consists of four rings (denoted M, S, P and L) and a coaxial rod . Using low-dose electron microscopy and image averaging methods on negatively stained and frozen-hydrated preparations, we examined whole basal body complexes and subcomplexes obtained by dissociation in acid . Dissociation occurs in steps, allowing us to obtain images of substructures lacking the M ring, lacking the M and S rings, and lacking the M and S rings and the proximal portion of the rod . We obtained images of the L and P ring subcomplex . The existence of a subcomplex missing only the M ring suggests either that the S and M rings derive from two different proteins, or that the M ring is a labile domain of a single protein, which makes up both rings . At the 25 to 30 A resolution of our averaged images, the L, P and S rings appear cylindrically symmetric . Images of the M ring show variability that may be due to differences in angular orientation of the grid, but equally could be due to structural variations . Three-dimensional reconstructions of these structures from the averaged images reveal the internal structure and spatial organization of these components.

J Mol Biol, 1992 Jan 5, 223(1), 27 - 30
Interdomain salt bridges modulate ligand-induced domain motion of the sulfate receptor protein for active transport; Jacobson BL et al.; The refined crystal structure of the liganded form of the Salmonella typhimurium sulfate-binding protein, a periplasmic receptor of active transport, is made up of two globular domains bisected by a deep cleft wherein the dehydrated sulfate is completely engulfed and bound by hydrogen bonds and van der Waals' forces . Two salt bridges (between Glu15 and Arg174 and between Asp68 and Arg134) span the cleft opening . To elucidate the role of the inter-domain salt bridges in the ligand-induced domain motion, the acidic residues were changed (singly and together) to their corresponding amide side-chains by site-directed mutagenesis of the recombinant Escherichia coli sulfate-binding protein . Rapid kinetics and equilibrium measurements of sulfate binding to the purified mutant proteins demonstrate that these salt bridges stabilize the closed liganded form of the receptor and modulate the rate of cleft opening . Our results have new implications in understanding the dynamics of many other multidomain proteins that undergo similar large-scale domain motions.

J Clin Pathol, 1992 Jan, 45(1), 34 - 6
Salmonella bacteraemia in England and Wales, 1981-1990; Threlfall EJ et al.; AIMS: To report the incidence of nontyphoidal salmonellas in England and Wales and identified in the Division of Enteric Pathogens, London between 1981 and 1990 . METHODS: Strains were serotyped and phage typed for Salmonella typhimurium, S enteritidis, and S virchow, using established methods . RESULTS: Overall, less than 2% of nontyphoidal salmonellas isolated from humans were from blood culture . The highest numbers of bloodstream isolates were from infections caused by S enteritidis and S typhimurium, but the highest incidence of septicaemias was attributable to infections with S cholerae-suis, S dublin, and S virchow . 2.2% of S typhimurium isolates phage type 204C were from blood culture; likewise, 5.5% of S virchow phage type 19 . This could be a cause for concern as most isolates of both these phage types are multiresistant to antimicrobial drugs . CONCLUSIONS: Salmonella septicaemia is rare in England and Wales in other than a few serotypes of limited epidemiological importance.

Mol Microbiol, 1992 Jan, 6(1), 47 - 57
Membrane topology of the integral membrane components, OppB and OppC, of the oligopeptide permease of Salmonella typhimurium; Pearce SR et al.; The oligopeptide permease of Salmonella typhimurium is a periplasmic binding protein-dependent transport system . Five gene products, OppABCDF, are required for the functioning of this transporter, two of which (OppB and OppC) are highly hydrophobic, integral membrane proteins and are responsible for mediating passage of peptides across the cytoplasmic membrane . OppB and OppC are each predicted, from their sequences, to span the membrane many times . In this paper we describe experimental evidence confirming these predictions using a combination of biochemical, immunological and genetic procedures . Each of these two proteins is shown to span the membrane six times, with the N- and C-termini both being located at the cytoplasmic face of the membrane . Opp is apparently a typical member of the ABC (ATP-binding cassette) superfamily of transporters . These findings, therefore, have general implications for the organization and function of other ABC transporters, including the human multidrug resistance protein and the product of the cystic fibrosis gene.

Environ Mol Mutagen, 1992, 19(1), 53 - 70
Quantitative structure-activity relationship investigation of the role of hydrophobicity in regulating mutagenicity in the Ames test: 2 . Mutagenicity of aromatic and heteroaromatic nitro compounds in Salmonella Typhimurium TA100; Debnath AK et al.; A quantitative structure-activity relationship (QSAR) has been derived for the mutagenic activity of 117 aromatic and heteroaromatic nitro compounds acting on Salmonella typhimurium TA100 . Relative mutagenic activity is bilin-early dependent on hydrophobicity, with an optimal log P of 5.44, and is linearly dependent on the energy of the lowest unoccupied molecular orbital of the nitro compound . The dependence of mutagenic activity on hydrophobicity and electronic effects is very similar for TA98 and TA100 . Mutagenic activity in TA100 does not depend on the size of the aromatic ring system, as its does in TA9 . The effect of the choice of assay organism, TA98 versus TA100, on nitroarene QSAR is seen to be similar to the effect previously found for aminoarenes . Lateral verification of QSARs is presented as a tool for establishing the significance of a new QSAR.

Environ Mol Mutagen, 1992, 19(1), 37 - 52
A QSAR investigation of the role of hydrophobicity in regulating mutagenicity in the Ames test: 1 . Mutagenicity of aromatic and heteroaromatic amines in Salmonella typhimurium TA98 and TA100; Debnath AK et al.; Quantitative structure-activity relationships (QSAR) have been derived for the mutagenic activity of 88 aromatic and heteroaromatic amines acting on Salmonella typhimurium TA98 + S9 and 67 amines acting on TA100 + S9 . Mutagenic activity is linearly dependent on hydrophobicity, the energy of the highest occupied molecular orbital, and the energy of the lowest unoccupied molecular orbital of the amine . The dependence of mutagenic activity on hydrophobicity and electronic effects is nearly identical for TA98 and TA100 . Mutagenic activity in TA98 is also found to depend on the size of the aromatic ring system . Different QSARs are derived for the mutagenic activity of hydrophilic amines (log P less than 1) acting on either TA98 or TA100 . The mechanism of amine activation and reaction with DNA is considered in light of these findings.

Environ Mol Mutagen, 1992, 19(1), 14 - 20
Direct-acting mutagenic activity in white, rosé, and red wines with the Ara test of Salmonella typhimurium; Ariza RR et al.; Thirty-two commercially produced white, rose, and red wines from Spain were assayed for genotoxicity . The Ara forward mutagenicity assay with Salmonella typhimurium served as the test system . All the wines were mutagenic in the absence of mammalian microsomal activation (S9 mix) and/or glycosidase activities with the exception of one rose wine which gave a clear dose-response relationship, although its mutagenic potency was considered statistically nonsignificant . The mutagenic activity covered nearly a 30-fold range . Compared to white and rose wines, red wines showed the highest levels of mutagenicity; this wine type included four "very potent" (greater than 3,000 AraR mutants/ml) mutagenic wines . The level of wine mutagenicity did not correlate with either the region or the year of production (vintage) . Individual winery methods are suggested as primarily responsible for variations in mutagenic activity . The present study with the Ara test supports the possibility that wine components other than the flavonols quercetin and rutin are the major putative mutagens: (1) white wines, as well as rose or red wines, were detected as being mutagenic; (2) in no case was activation required for the detection of mutagenicity; (3) mutagen(s) were detected mainly (red wine) when not exclusively (white and rose wine) in the polar fraction from XAD-2 chromatography . The high sensitivity of the Ara test has allowed the screening of the mutagenicity of a variety of wines with no previous process of extraction or concentration . The comparison of the mutagenic activity of the entire complex mixture to that of its lyophilized residue has revealed a positive synergistic role for ethanol in the mutagenicity of certain wines . Finally, this work suggests that the Ara test is a useful tool for mutagenicity screening in wines . Thus, this test might play an important role in elucidating the genotoxic mechanism of action of alcoholic beverages, and for studying optional production methods to decrease the mutagenicity of commercial wines.

J Bacteriol, 1992 Jan, 174(2), 643 - 5
Fumarate or a fumarate metabolite restores switching ability to rotating flagella of bacterial envelopes; Barak R et al.; Flagella of cytoplasm-free envelopes of Escherichia coli or Salmonella typhimurium can rotate in either the counterclockwise or clockwise direction, but they never switch from one direction of rotation to another . Exogenous fumarate, in the intracellular presence of the chemotaxis protein CheY, restored switching ability to envelopes, with a concomitant increase in clockwise rotation . An increase in clockwise rotation was also observed after fumarate was added to partially lysed cells of E . coli, but the proportion of switching cells remained unchanged.

J Bacteriol, 1992 Jan, 174(2), 492 - 8
Molecular analysis of the Escherichia coli phoP-phoQ operon; Kasahara M et al.; The phoP-phoQ operon of Salmonella typhimurium is a member of the family of two-component regulatory systems and controls expression of the phoN gene that codes for nonspecific acid phosphatase and the genes involved in the pathogenicity of the bacterium . The phoP-phoQ operon of Escherichia coli was cloned on a plasmid vector by complementation of a phoP mutant, and the 4.1-kb nucleotide sequence, which includes the phoP-phoQ operon and its flanking regions, was determined . The phoP-phoQ operon was mapped at 25 min on the standard E . coli linkage map by hybridization with the Kohara mini set library of the E . coli chromosome (Y . Kohara, K . Akiyama, and K . Isono, Cell 50:495-508, 1987) . The predicted phoP and phoQ gene products consist of 223 and 486 amino acids with estimated molecular masses of 25,534 and 55,297 Da, respectively, which correspond well with the sizes of the PhoP and PhoQ proteins identified by the maxicell method . The amino acid sequences of PhoP and PhoQ of E . coli were 93 and 86% identical, respectively, to those of S . typhimurium.

J Bacteriol, 1992 Jan, 174(2), 390 - 7
Regulation of the Salmonella typhimurium metA gene by the metR protein and homocysteine; Mares R et al.; The DNA sequence of the Salmonella typhimurium metA control region is presented . S1 nuclease mapping was used to determine the transcription initiation site . By measuring beta-galactosidase levels in Escherichia coli strains lysogenized with lambda phage carrying a metA-lacZ gene fusion, the MetR protein was shown to activate the metA gene . Homocysteine, an intermediate in methionine biosynthesis, plays a negative role in the MetR-mediated activation mechanism . Gel mobility shift assays and DNase I protection experiments showed that the MetR protein binds to a DNA fragment carrying the metA control region and protects a 26-bp region beginning 9 bp upstream of the -35 promoter sequence.

J Bacteriol, 1992 Jan, 174(1), 84 - 91
The Salmonella typhimurium virulence plasmid complement resistance gene rck is homologous to a family of virulence-related outer membrane protein genes, including pagC and ail; Heffernan EJ et al.; A fragment of the Salmonella typhimurium virulence plasmid containing the rck locus, when cloned in the recombinant cosmid pADE016, was shown previously to confer high-level complement resistance on both rough and smooth Escherichia coli, Salmonella minnesota, and S . typhimurium and was associated with the production of an outer membrane protein . We determined the nucleotide sequence of the fragment containing the rck locus . Mutations in the two major open reading frames confirmed that the complement resistance mediated by pADE016 was due to a single 555-bp rck gene encoding a 17-kDa outer membrane protein . Analysis of the rck gene revealed that the Rck outer membrane protein consisted of 185 amino acid residues, with a calculated postcleavage molecular mass of 17.4 kDa . Rck is homologous to a family of outer membrane proteins expressed in gram-negative bacteria, two of which have been associated with virulence-related phenotypes: PagC, required by S . typhimurium for survival in macrophages and for virulence in mice; and Ail, a product of the Yersinia enterocolitica chromosome capable of mediating bacterial adherence to and invasion of epithelial cell lines . Rck, most closely related to PagC, represents the third outer membrane protein in this five-member family with a distinct virulence-associated phenotype.

J Bacteriol, 1992 Jan, 174(1), 24 - 9
The CobII and CobIII regions of the cobalamin (vitamin B12) biosynthetic operon of Salmonella typhimurium; Escalante-Semerena JC et al.; A detailed deletion map of the CobII and CobIII regions of the cobalamin biosynthetic (cob) operon of Salmonella typhimurium LT2 has been constructed . The CobII region encodes functions needed for the synthesis of lower ligand 5,6-dimethylbenzimidazole (DMB); CobIII encodes functions needed for the synthesis of the nucleotide loop that joins DMB to the corrin macrocycle . The genetic analysis of 117 deletion, insertion, and point mutations indicates that (i) the CobII and CobIII mutations are contiguous--that is, they are grouped according to function; (ii) the CobII region is composed of four complementation groups (cobJKLM); (iii) cobM mutations do not complement mutations in any of the other three CobII groups; and (iv) CobIII mutations include three complementation groups that correspond to the cobU, cobS, and cobT genes.

Environ Mol Mutagen, 1992, 20(1), 12 - 8
Molecular analysis of mutations induced by the intercalating agent ellipticine at the hisD3052 allele of Salmonella typhimurium TA98; DeMarini DM et al.; We have used DNA colony hybridization, the polymerase chain reaction (PCR), and direct DNA sequencing to determine the mutations induced by the intercalating agent ellipticine in Salmonella typhimurium TA98 in the presence of S9 . Of 400 ellipticine-induced revertants that were selected at a mutant yield that was ninefold over the background, 85.5% contained a GC or CG deletion within a common CGCGCGCG hotspot; this deletion occurred among 47% of the spontaneous revertants . In addition to this hotspot, the ellipticine spectrum contained two deletion warmspots that reside opposite each other in looped-out regions of a possible DNA secondary structure . Ellipticine and its metabolites likely revert Salmonella strain TA98 by forming DNA adducts that promote slippage-mismatches and by stabilizing these slipped mismatched sequences via intercalation . The involvement of these mechanisms, along with a likely role for DNA secondary structures and a possible role for DNA gyrase, may account for the site specificity exhibited by ellipticine in strain TA98.

Mutagenesis, 1992 Jan, 7(1), 77 - 81
Study on the mutagenicity of brandy with the Ara test; Ariza RR et al.; The forward mutation assay to L-arabinose resistance (Ara test) in Salmonella typhimurium was used to demonstrate that evaporated residues of brandy had direct-acting mutagenic activity . The mutagenicity covered a 100-fold range, from 13482 to 127 AraR induced mutants/ml brandy equivalent . Rat liver S9 mix suppressed the mutagenic activity of brandy in the Ara test . The inactivating capacity was independent of microsomal monoxygenase enzymes and appeared to be mediated through a heat stable component of the S9 fraction . Catalase was identified as the putative S9 component responsible for its inactivating capacity . The implication of reactive oxygen species in the direct-acting mutagenicity of brandy was supported by the higher sensitivity of Escherichia coli bacterial strains deficient in two major cellular antioxidant defense (glutathione and/or catalase) compared to their parental wild-type . Phenolic compounds of a polar nature could be responsible for the mutagenicity through the production of reactive oxygen intermediates . Non-matured beverages (gin and non-matured rum) were non-mutagenic . It is conceivable that mutagenic phenolics might be extracted from the wood during maturation in the barrel . Autoxidation of phenolic compounds could be a common mechanism in the mutagenicity of complex mixtures of plant origin.

Mutagenesis, 1992 Jan, 7(1), 37 - 9
Influence of the triazine ring on the mutagenicity of triazinoindoles and some congeners; Lopez-de-Cerain A et al.; Three compounds, which could be considered as precursors or derivatives of the 3-(4'-substituted-benzylidenamino)5H- 1,2,3-triazin{5,4b}indol-4-one series, were selected from the study of their mutagenic activity . Ames tests were performed study of their mutagenic activity . Ames tests were performed using the Salmonella typhimurium strains TA97, TA98, TA100, and TA102, according to the preincubation procedure, both with and without metabolic activation . The 3-amino-5H-1,2,3-triazin{5,4b}indol-4-one has been shown to be a strong S9-independent mutagen, which reverts frameshift and substitution mutations . Nevertheless its potency increases with the addition of microsomal fraction . In contrast, the 2-benzyliden-1-(3-aminoindol)-2-carbohydrazide and the 3-aminoindol-2-carbohydrazide congeners were not mutagenic . These results suggest that the 1,2,3-triazine ring is the principle substructure responsible for the mutagenicity of the triazinoindole congeners studied.

Mutagenesis, 1992 Jan, 7(1), 31 - 5
Bacterial mutagenic evaluation of a series of 4' substituted derivatives of 3-benzylidenamino-5H-1,2,3-triazin{5,4b}indol-4-one; Garcia E et al.; The mutagenicity of ten triazinoindole derivatives was studied in bacteria . The compounds form part of a 3-(4'-substituted-benzylidenamino)-5H-1,2,3-triazin{5,4-b}in dol-4-one series and differ in the physicochemical properties of the substituent at the 4' position of the benzylidenamino group: -H, -OH, -COOH, -OCH3, -COOCH3, -NHCOCH3, -C1, -NO2, -C6H5, and -OC6H5 . They were tested in the TA97, TA98, TA100, and TA102 strains of Salmonella typhimurium, both with and without metabolic activation, using the preincubation procedure . Only the derivatives with phenyl and phenoxy substituents were non-mutagenic . The remaining compounds significantly increased the number of His+ revertants and showed three patterns of activity based upon their mutagenic potency and their response to metabolic activation . Size and hydrophobicity of the 4'-substituents are the physicochemical characteristics that most differentiate the mutagenic triazinoindole derivatives from the nonmutagenic ones.

Mutagenesis, 1992 Jan, 7(1), 13 - 8
Sensitivity of Salmonella typhimurium TA97a to the type of agar used for preparation of Vogel-Bonner plates; Wilcox P et al.; Recent problems with the supply of Difco bacto agar have forced some laboratories to evaluate alternative agars for use in the Salmonella/microsome assay . This led to the independent observation in two laboratories (Boots and Glaxo) that Salmonella typhimurium TA97a is sensitive to certain types of agar that may be used to prepare Vogel-Bonner minimal medium plates . A programme of work was, therefore, undertaken to investigate this phenomenon; 9-aminoacridine hydrochloride (at Boots) and 4-nitro-o-phenylenediamine (at Glaxo) were tested against TA1537 and TA97a using Vogel-Bonner plates prepared with a number of different agars . Three agars (Lab M, Difco Bi-tek and Beckton Dickinson granulated) were identified which, although supporting normal growth of TA1537 revertant colonies, gave much reduced control counts and responses to the mutagens with TA97a . One agar, Becton Dickinson grade A, gave poor responses with TA1537 but produced satisfactory results with TA97a . In contrast to the Vogel-Bonner plates, varying the type of agar used in the top agar overlays had little effect on the responses obtained . On the basis of these comparisons, Becton Dickinson purified agar was selected as a suitable alternative to Difco bacto and it was concluded that laboratories using agars other than these, or purchasing pre-poured plates without specifying the type of agar, should be made aware of potential problems with TA97a.

J Cancer Res Clin Oncol, 1992, 118(6), 447 - 52
Protective role of aqueous turmeric extract against mutagenicity of direct-acting carcinogens as well as benzo {alpha} pyrene-induced genotoxicity and carcinogenicity; Azuine MA et al.; Turmeric (Curcuma longa Linn.) has been shown to inhibit chemical carcinogenesis . In this study, we compared the chemopreventive efficacy of an aqueous turmeric extract (AqTE) and its constituents, curcumin-free aqueous turmeric extract (CFAqTE) and curcumin, using the Salmonella typhimurium mutagenicity assay and the bone marrow micronucleus test in female Swiss mice . AqTE exhibited antimutagenic activity against direct-acting mutagens, 4-nitro-O-phenylenediamine and 1-methyl-3-nitro-1-nitrosoguanidine, in strains TA 98 and TA 100 respectively . Both AqTE and CFAqTE inhibited the mutagenicity of benzo {alpha}pyrene in the two strains in the presence of Aroclor-1254-induced rat liver homogenate . The inhibition in both studies was dose-dependent . Administration of AqTE, CFAqTE and curcumin at a dose of 3 mg/animal 18 h prior to i.p . benzo {alpha}pyrene injection (250 mg/kg) significantly inhibited bone marrow micronuclei formation in female Swiss mice by 43%, 76%, and 65% respectively . Furthermore, the incidence and multiplicity of forestomach tumours induced by benzo {alpha}pyrene (1 mg/animal, twice weekly, p.o . for 4 weeks) in female Swiss mice were significantly inhibited by AqTE, CFAqTE and curcumin given 2 weeks before, during and after the carcinogen treatment . These data indicate that the protection against genomic damage by turmeric extract and its components tested could be necessary for some aspects of its cancer chemoprevention.

Environ Mol Mutagen, 1992, 19(4), 338 - 45
Mutagenicity of beta-alkyl substituted acrolein congeners in the Salmonella typhimurium strain TA100 and genotoxicity testing in the SOS chromotest; Eder E et al.; The beta-alkyl substituted acrolein congeners crotonaldehyde, trans-2-pentenal, trans-2-hexenal, 2,4-hexadienal, and trans-2-heptenal were clearly mutagenic in a slightly modified preincubation Ames test with Salmonella typhimurium TA100 with and without S9 mix using a threefold bacterial cell density and a 90-min preincubation time, whereas trans-cis-2,6-nonadienal did not show any mutagenic activity . The greatest impediment to adequate mutagenicity testing of these compounds is their toxicity toward bacteria . Within the congener family tested, toxicity increases as a function of both chain length and lipophilicity, and it becomes more and more difficult to demonstrate mutagenicity . Mutagenicity decreases with increasing chain length . This effect may be explained by increasing toxicity . The effect of S9 mix seems to be mostly nonenzymatic detoxication by nonspecific scavanger protection of bacterial cytotoxicity . No indication could be found that bioactivation plays a role in S9-mediated reduction of bacterial cytotoxicity . Although positive mutagenic outcomes could be obtained with the SOS chromotest for other alpha, beta-unsaturated carbonyl compounds, these acrolein congeners were not genotoxic in this test, most probably because they are toxic for the Escherichia coli bacteria PQ37 and PQ243.

Environ Mol Mutagen, 1992, 19(4), 331 - 7
Ozone is mutagenic in Salmonella; Dillon D et al.; Ozone is a highly reactive gas that has been tested for genotoxicity in a number of systems . Induced genetic damage resulting from ozone treatment may not be readily observed because of the high toxicity of the chemical and difficulties in generating and administering controlled concentrations . The mutagenicity of ozone was investigated in Salmonella typhimurium using a plate test protocol designed for reactive vapours and gases . Ozone, at two to three consecutive doses, induced weak, albeit statistically significant, mutagenic responses in tester strain TA102 with and without Aroclor-induced rat liver S9 (lowest effective mean concentration of 0.019 ppm; 35 min total exposure) . However, dose-related responses were not always obtained . No mutagenicity was detected in strains TA98, TA100, or TA1535, with or without S9 . In strain TA104, ozone induced a weak response only at a single dose with S9; this response was not reproducible . Mutagenicity was dependent on the ozone flow rate and total exposure time, with variations in the optimum dose-time regimen leading to toxicity or complete inactivity . The data show that ozone is a very weak bacterial mutagen and only when tested under narrowly prescribed, subtoxic dosing conditions.

Environ Mol Mutagen, 1992, 19(4), 311 - 5
Structure-activity relationship in the mutagenic effect of chiral or racemic 2-bromo-propanamides on Salmonella typhimurium; Dolzani L et al.; Some 2-bromo-propanamides were prepared and tested for direct mutagenicity in Salmonella typhimurium TA 100 . Results confirm the mutagenic activity of 2-bromo-N-benzyl-propanamide and indicate that it is independent of enantiomeric configuration . A variation in the chemical structure, namely, the addition of a methyl group at the benzylic carbon, causes the four resulting diastereomers to be devoid of any activity . Conversely, some racemic ring-substituted methoxy and/or hydroxy derivatives of the parent compound displayed mutagenic properties, causing an increase in the number of his+ revertants up to 524 per milligram per plate.

Indian J Med Res, 1992 Jan, 95, 17 - 20
Salmonella typhimurium enterotoxin mediated fluid secretion; Khurana S et al.; Unidirectional Na+ and Cl- fluxes were studied in rats treated with S . typhimurium enterotoxin (S-LT) . There was net absorption of Na+ and Cl- in the control group, while in the toxin treated animals there was net secretion of Na+ and Cl- (P less than 0.001) . There was no change in the transport of D-glucose in the toxin treated group as compared to the control animals . The Na+, K(+)-ATPase pump was unaltered in the S-LT treated animals (198.67 +/- 11.23 nmoles Pi/mg protein/min) as compared to the control group (189.93 +/- 10.09 nmoles Pi/mg protein/min) . There was no change in the unidirectional fluxes of Ca+2 in the S-LT treated animals as compared to the control animals, suggesting no change in the permeability of the S-LT treated intestinal membrane to Ca+2.

Vaccine, 1992, 10(5), 337 - 40
Prophylaxis of Salmonella abortus ovis-induced abortion of sheep by a Salmonella typhimurium live vaccine; Linde K et al.; A Salmonella typhimurium live vaccine with optimal level of attenuation for sheep, constructed by means of 'metabolic drift' mutations, was tested for its efficacy in preventing Salmonella abortus ovis-induced abortions . In two field trials in Kirgiziya, 78,000 to 100,000 first delivery sheep received a fully tolerated single dose of 10(9) c.f.u . live vaccine 2 months before to 4 months after insemination . Alternatively, they were immunized twice with commercial inactivated S . abortus ovis vaccine, or they served as non-immunized controls . The S . abortus ovis-induced abortion frequency in the controls was greater than or equal to 30%, in sheep immunized with inactivated vaccine greater than or equal to 11% . In flocks immunized with live vaccine, the S . abortus ovis-induced abortion frequency did not exceed 0.1% . Thus, use of 'metabolic drift' mutations for construction of stable vaccine strains optimally attenuated for the particular host species proved to be relevant to practice.

Eur J Epidemiol, 1992 Jan, 8(1), 120 - 1
Human salmonellosis transmitted by a domestic turtle; Dessi S et al.; Salmonella typhimurium was isolated in the culture test of a small child admitted to hospital suffering from febrile gastroenteritis with stools containing traces of mucus and blood . Her mother also resulted positive for this microorganism . The family had recently bought a small turtle, imported from Florida, at the city fair . Further tests revealed Salmonella typhimurium in both the turtle's feces and the water in its tank.

Environ Mol Mutagen, 1992, 19(3), 253 - 8
Mutagenicity of benzo(a)pyrenyl-1-sulfate in the Ames test; Irwin SE et al.; Comparison of the mutagenicity of nine isomeric benzo(a)pyrenyl {B(a)P} phenols conjugated with either sulfate or glucuronide was carried out using strain Salmonella typhimurium TA98 . Of the nine conjugates tested, only B(a)P-1-sulfate was mutagenic . Accordingly, the mutagenicity of B(a)P-1-sulfate was compared with that of B(a)P and 1-hydroxybenzo(a)pyrene {B(a)P-1-OH} in the presence and absence of rat lung S9 and Aroclor-induced liver S9 with and without an NADPH-generating system . B(a)P-1-sulfate was slightly mutagenic, whereas B(a)P and the 1-hydroxy derivative were nonmutagenic when S9 fractions and NADPH were omitted . Addition of induced liver S9 with NADPH caused mutagenicity with B(a) -1-OH greater than B(a)P greater than B(a)P-1-sulfate . B(a)P-1-sulfate was the only mutagenic species when lung S9 was added . This mutagenicity did not require NADPH . Sodium sulfite, an inhibitor of arylsulfatase, decreased the mutagenicity of B(a)P-1-sulfate . These data suggest that a unique mutagenic species is generated from B(a)P-1-sulfate via arylsulfatase in rat lung.

Environ Mol Mutagen, 1992, 19(3), 244 - 52
Effects of plate preparation on results in microbial mutation assays; Majeska JB et al.; Glucose autoclaved in an alkaline phosphate solution (heated glucose+salts, HGS) results in the production of a moiety that is nonmutagenic but can interact with a series of 4-{2-(aryl)ethenyl}-2,6-dimethylphenols to result in an increase in bacterial revertants that is dependent on the amount of HGS in the minimal agar plates . The reaction between the HGS and the chemical to form a mutagen is independent of the presence of bacteria, does not result in a nutritive analog to enhance growth of the auxotrophic bacteria, and is effective only in Salmonella typhimurium and Escherichia coli strains that contain the plasmid pKM101 . A sufficient amount of this glucose product may be formed in normal plate preparation to produce apparent mutagenic activity of these chemicals.

Avian Dis, 1992 Jan-Mar, 36(1), 24 - 9
Reaction of the avian respiratory system to intratracheally administered avirulent Salmonella typhimurium; Toth TE et al.; Chickens were inoculated intratracheally (IT) with the SR-11 Salmonella typhimurium deletion mutant x4062 strain . Data collected for 8 days postinoculation (PI) were: signs of respiratory and gastrointestinal disease; histological lesions; the influx, phagocytic proportion, and phagocytic capacity of avian respiratory phagocytes (ARPs); and the proportion of granulocytes vs . macrophages in the lung tissues and lavage fluids of the lungs and air sacs . S . typhimurium-inoculated chickens had no clinical signs of gastrointestinal or respiratory disease but had various degrees of inflammatory changes in the lungs . At 5 hr PI, S . typhimurium-inoculated chickens had approximately 53-fold more ARPs than mock-inoculated controls . Between 26 hr and 8 days PI, the number of ARPs from S . typhimurium-inoculated birds was not significantly higher than the number from the mock-inoculated controls . Flow cytometric analysis of ARPs demonstrated that the proportion of phagocytic ARPs and the phagocytic capacity of ARPs from S . typhimurium-inoculated chickens were significantly higher between 5 and 26 hr PI than those of the ARPs from mock-inoculated chickens . Kinetic changes over 8 days in the granulocyte/macrophage ratios in the lavage fluids, as compared with kinetic changes in the lung tissues, suggested that the granulocytes generally represent a much higher proportion of the ARPs, and egress earlier and in much larger numbers from the tissues to the lumen of lungs and air sacs than do macrophages.

Avian Dis, 1992 Jan-Mar, 36(1), 139 - 42
Effect of feeding selected short-chain fatty acids on the in vivo attachment of Salmonella typhimurium in chick ceca; McHan F et al.; Two groups of 20 chicks each were fed 1% fatty acid continuously starting at 1 day of age, while a control group of 20 chicks received unsupplemented feed . At 2 days of age, chicks were inoculated orally with 1 ml of Salmonella typhimurium (1 x 10(6) colony-forming units/ml) . Ceca were obtained from six chicks of each group at 7, 14, and 21 days of age . At 14 days of age, formic and propionic acids had statistically reduced Salmonella recovery by 2.56 logs and 3.09 logs, respectively, compared with controls . At 21 days of age, both test groups showed significant reductions of approximately 3.6 logs compared with controls . There were no statistical differences in body weights among the groups at 21 days of age.

Environ Mol Mutagen, 1992, 19 Suppl 21, 2 - 141
Salmonella mutagenicity tests: V . Results from the testing of 311 chemicals; Zeiger E et al.; 311 chemicals were tested under code, for mutagenicity, in Salmonella typhimurium; 35 of the chemicals were tested more than once in the same or different laboratories . The tests were conducted using a preincubation protocol in the absence of exogenous metabolic activation, and in the presence of liver S-9 from Aroclor-induced male Sprague-Dawley rats and Syrian hamsters . Some of the volatile chemicals were also tested in desiccators . A total of 120 chemicals were mutagenic or weakly mutagenic, 3 were judged questionable, and 172 were non-mutagenic . The remaining 16 chemicals produced different responses in the two or three laboratories in which they were tested . The results and data from these tests are presented.

Environ Mol Mutagen, 1992, 19(2), 167 - 81
Evaluation of the mutagenic and genotoxic activities of 48 nitroimidazoles and related imidazole derivatives by the Ames test and the SOS chromotest; De Meo M et al.; The mutagenic and genotoxic activities of 48 nitroimidazoles and related imidazole derivatives have been evaluated by using modified versions of the Ames test and the SOS Chromotest . Salmonella typhimurium tester strain TA 100 was used with and without metabolic activation in the Ames test and Escherichia coli tester Strain PQ 37 was used with and without metabolic activation in the SOS Chromotest . Including metronidazole and dimetridazole, 45 derivatives were mutagenic and genotoxic . The mutagenic potencies (MP) ranged from 0.127 to 53,717 revertants/nmol while the SOS induction powers (SOSIP) ranged from 0.00131 to 107 IF/nmol . The overall correlation between MP and SOSIP was r = 0.845 (n = 84) as calculated by linear regression analysis . A higher correlation was observed between MP and SOSIP without the S9 mix than with it . Among the imidazole derivatives, the 5-nitroimidazoles with a lactam ring at the 2-position showed the highest MP and SOSIP . The presence of a nitro group at the 5-position was critical for the mutagenicity and the genotoxicity of the derivatives . Substituents at the 1- and 2-positions were also found to modulate these activities.

Environ Mol Mutagen, 1992, 19(2), 139 - 46
Conditions for detecting the mutagenicity of divalent metals in Salmonella typhimurium; Pagano DA et al.; The mutagenesis of metals in bacteria, as reported in the literature, can best be described as inconsistent . We report that cobalt chloride (Co++), ferrous sulfate (Fe++), manganese sulfate (Mn++), cadmium chloride (Cd++), and zinc chloride (Zn++) could be reproducibly detected as mutagens in Salmonella strain TA97 when preincubation exposures were made in sterile, distilled, deionized water, or in Hepes buffer in NaCl2/KCl2, rather than the standard sodium phosphate buffer . Co++ was also mutagenic under standard preincubation conditions . The individual components of Vogel-Bonner medium, i.e., potassium and ammonium phosphate, citrate, and magnesium sulfate, inhibit mutagenesis by these metals . The phosphates and the citrate probably inhibit by chelating the metals, while data are presented to suggest that Mg++ inhibition of metal mutagenesis is due to competitive inhibition for active transport via the magnesium active transport system in Salmonella . The chelator, diethyldithiocarbamate, inhibited the mutagenicity of Co++, Fe++, Zn++, and Mn++, but enhanced the mutagenicity of Cd++ . The results presented show that divalent metals can be detected as mutagens in Salmonella, and that their lack of detection as mutagens is not due to an inherent insensitivity of Salmonella but to their interaction with media components and/or passive and active transport processes.

Environ Mol Mutagen, 1992, 19(2), 112 - 24
Metal, mutagenicity, and biochemical studies on bivalve molluscs from Spanish coasts; Rodriguez-Ariza A et al.; Three species of marine bivalve molluscs (Chamelea gallina, Ruditapes decussatus, and Crassostrea gigas) have been studied in order to evaluate the levels of pollution on the South Atlantic Spanish littoral . Several transition metals (Cu, As, Cd, Sn, Hg, Pb) were determined as a general index of total contamination . Animals from putative contaminated areas exhibited higher metal contents than those from cleaner waters . C . gigas showed 5-20-fold higher total metal content than the other two species . The mutagenicity of ethanolic extracts was assayed by using both the His reversion and the Ara forward mutation tests . Mollusc tissues from the three species did not contain genotoxins active on TA98 (frameshift mutations) or TA100 (mainly G:C base-pair substitutions), but did contain direct-acting genotoxins of a polar nature and oxidative type . This was based on the following observations: 1) mammalian metabolic activation was not required for mutagenicity, 2) mutagens were eluted with the polar fraction from XAD-2 columns, and 3) mutagenic responses were observed with Salmonella typhimurium TA102 (A:T base-pair substitutions; sensitive to oxidative damages) and Escherichia coli catalase-deficient (AraR forward mutations) strains . No relevant differences were found in the mutagenicity of mollusc extracts from areas with different pollution levels . Otherwise, our data suggest that, in general, animals living in contaminated environments had fewer genotoxins of oxidative type than those from less polluted areas . Such a result might be explained by the observation of increased levels of a number of detoxifying and antioxidant enzymes, such as glutathione-S-transferase, glutathione-peroxidase, catalase, and superoxide dismutase . Thus, contaminated animals seem to be better protected against the oxidative damages induced by metals, in agreement with their lower malondialdehyde levels . To what extent the responsible mutagenic compounds are of endogenous origins, or "Nature's pesticides" (the major toxic chemicals ingested by phytoplankton filter-feeders), and/or the result of human activities remains to be determined.

Vaccine, 1992, 10(1), 61 - 6
Humoral and cell-mediated immunity in mice after immunization with live oral vaccines of Salmonella typhimurium: auxotrophic mutants with two attenuating markers; Mitov I et al.; Persistence and clearance of the vaccinal strains, humoral and cell-mediated immune response and protective immunity were assessed in ICR mice, immunized intraperitoneally or intragastrically with double-marker auxotrophic mutants of Salmonella typhimurium strains 1771 and 3334 (his-pur-) . Strain 3334 possesses in addition the antiepidemic Hst (high sensitivity to tensides) marker which confers decreased survival in the gut and environment . The results showed that the strains are not overattenuated . They revealed preserved multiplication capacity, established carrier state for 28-30 days and induced humoral and cell-mediated immunity as measured by passive haemolysis and microagglutination or footpad swelling tests, respectively . The immune response was determined by biological features of the strains . Strain 1771 induced synthesis of O- and H-antibodies 7-11 days earlier than strain 3334 . Footpad reactions appeared 3-4 days after immunization and a week before the serum antibodies . Cell-mediated immunity showed clear correlation with the protection against challenge with a virulent strain . The present results suggest that the double-marker auxotrophic mutants of S . typhimurium might prove very useful in the development of a live vaccine in further studies on livestock.

Poult Sci, 1992 Jan, 71(1), 59 - 63
Influence of coccidiosis on Salmonella colonization in broiler chickens under floor-pen conditions; Arakawa A et al.; The influence of coccidiosis on colonization of Salmonella typhimurium in broiler chickens under floor pen conditions was studied by semiquantitative methods . Chickens of two groups, unmedicated and medicated with nicarbazin (125 ppm via the feed), were exposed to three species of Eimeria (Eimeria tenella, Eimeria maxima, and Eimeria acervulina) at 2, 3, and 4 wk of age and given S . typhimurium in the feed 2 days later . Salmonella typhimurium was isolated most often (100%) from ceca of chickens exposed at 3 wk of age . Birds in the unmedicated group were positive for S . typhimurium at a higher rate than those in the medicated group . Salmonella typhimurium was detected in livers only in a few unmedicated birds.

Metabolism, 1992 Jan, 41(1), 1 - 2
Fish oil decreases natural resistance of mice to infection with Salmonella typhimurium; Chang HR et al.; Mortality rate in mice fed fish oil for 4 weeks was remarkably higher after a very low peroral (PO) challenge with Salmonella typhimurium, as compared with those fed diets rich in either corn oil or hydrogenated coconut oil, or a low fat (chow) diet . None of the surviving mice fed the fish oil diet showed bacterial counts in their spleens, unlike 45.4% to 66.6% of surviving mice fed high fat or low fat diets . The spleens of mice fed fish oil presented the highest number of bacteria 7 days after intraperitoneal infection with the same bacterial strain . Thus, the current studies demonstrate that a diet rich in fish oil decreases host resistance to infection.

FEMS Microbiol Lett, 1992 Jan 1, 69(2), 101 - 4
The role of ntrA in the anaerobic metabolism of Salmonella typhimurium; Fasciano A et al.; The possible involvement of NtrA in the expression of several anaerobically induced genes in Salmonella typhimurium was investigated . Unlike Escherichia coli, where hydrogenase 3 is ntrA dependent, the introduction of a mutation in ntrA had virtually no effect on the hydrogenase activity, thought to be hydrogenase 3, of S . typhimurium LT7 . Fumarate reductase and alcohol dehydrogenase activities were found to be diminished in ntrA mutant strains, but this may very well be indirect since fdhF mutant strains showed the same effect . These results suggest that in S . typhimurium NtrA is highly specific for the anaerobic expression of fdhF.

J Bacteriol, 1992 Jan, 174(2), 486 - 91
Molecular genetic analysis of the Escherichia coli phoP locus; Groisman EA et al.; We have cloned the Escherichia coli phoP gene, a member of the family of environmentally responsive two-component systems, and found its deduced amino acid sequence to be 93% identical to that of the Salmonella typhimurium homolog, which encodes a major virulence regulator necessary for intramacrophage survival and resistance to cationic peptides of phagocytic cells . The phoP gene was mapped to kilobase 1202 on the Kohara map (25-min region) of the E . coli genome (Y . Kohara, K . Akiyama, and K . Isono, Cell 50:495-508, 1987) and found to be transcribed in a counterclockwise direction . Both E . coli and S . typhimurium phoP mutants were more sensitive than their isogenic wild-type strains to the frog-derived antibacterial peptide magainin 2, suggesting a role for PhoP in the response to various stresses in both enteric species.

Free Radic Res Commun, 1992, 16(1), 1 - 10
Clastogenic and mutagenic actions of active species generated in the 6-hydroxydopamine/oxygen reaction: effects of scavengers of active oxygen, iron, and metal chelating agents; Gee P et al.; A pro-oxidant triphenol, 6-hydroxydopamine (6-OHDA), induced mutations in the Salmonella typhimurium TA 104 tester strain (over the concentration range to 800 microM), and induced chromosomal aberrations in cultured Chinese hamster ovary (CHO) cells at lower concentrations (up to 90 microM) . It was however only marginally mutagenic (up to cytotoxic levels of 200 microM) in the TA102 tester strain . Clastogenicity in the more sensitive CHO cell assay was mediated by activated oxygen . Superoxide dismutase decreased the incidence of chromosomal aberrations by 60% and catalase (or superoxide dismutase plus catalase) decreased the incidence to control levels . The clastogenicity of 6-OHDA was dependent upon unsequestered transition metal ions, since addition of EDTA plus desferrioxamine decreased chromosomal aberrations by 90% . The simplest explanation of the data is that genotoxicity is mediated by active species generated in a Fenton-type reaction between 6-OHDA and H2O2 catalyzed by traces of metals in the medium.

Folia Microbiol (Praha), 1992, 37(3), 188 - 92
Comparison of permuted region lengths in the genomes of related Salmonella typhimurium phages P22 and L; Spanova A; Lengths of permuted regions in the P22 and L phage genomes were estimated from the relative yields of DNA in many electrophoretic bands obtained using several restriction endonucleases . It was found that 3.6 kb (8.7%) of P22-DNA and 7.2 kb (17.8%) of L-DNA were circularly permuted . In both phages the sequential packaging process proceeded in the same direction and four headful-size DNA molecules were, on the average, cleaved in one packaging series . The differences in circular permutation may originate from different genome lengths because their average headful portions are very similar (42.5 kb in P22 and 42.3 kb in L).

Infection, 1992, 20 Suppl 2, S84 - 92
The role of GM-CSF in infection; Freund M et al.; GM-CSF is a hemopoietic growth factor with substantial effects on the proliferation of neutrophils, eosinophils and monocytes/macrophages . Its physiologic role in infection is still poorly understood . The gene for GM-CSF is constitutively transcribed in cells substantial for antiinfectious response . Various cells are activated and induced by TNF and IL-1 to synthesize GM-CSF . No systemic GM-CSF levels can be detected in patients with infection . It is likely that GM-CSF plays its physiological role in the immediate vicinity of the cells by which it is secreted . GM-CSF functionally activates neutrophils, monocytes/macrophages and eosinophils . It may augment T-cell proliferation and function . GM-CSF is effective in mice infected with Staphylococcus aureus or Salmonella typhimurium . Its effect in infectious disease in man should be explored.

Sb Ved Pr Lek Fak Karlovy Univerzity Hradci Kralove Suppl, 1992, 35(3), 219 - 42
{Genotoxic activity test of sodium fluoride in vitro}; Srb V et al.; The artificial drinking water fluoridization provided as a mass preventive measure against dental decay poses another substantial problem which is a possibility of genotoxic action . Up to this date, this matter remains still obscur and is discussed with more or less intensity from time to time . The mentioned fact supported authors to study the impact of short-term 24 hrs sodium fluoride (NaF) action in concentration range of 0-500 mg.1(-1) drinking water in the frame of so-called minimal testing set (analysis of chromosomal aberrations in human peripheral lymphocytes, Ames test) . For the initial NaF concentration applied, the reference value of 1 mg per 1 liter artificial fluoridization was estimated . The use of Ames test with TA 98 and TA 100 Salmonella typhimurium (+/- S9) strains showed no significant increase in revertants responsible of NaF mutagenic activity in any of applied concentrations (0-1300 mg per 1 Petri dish; = 0-520 mg.l-1 converted to the basic supplementative dose) . Cytogenetic analysis of peripheral lymphocytes showed more sensitivity than prototrofic salmonella test . Yet one order higher NaF concentration than its application norm 1 mg.l-1 (i.e . 11 mg.l-1) has induced the occurrence of 3.8% ABB after single addition for 24 hrs to the "healthy" blood cultivated in vitro at short-term . This accounts for a value close to the level of statistically significant difference with regard to the application norm recommended . This level has been even exceeded as for a total count of fragments and exchanged parts . Thus the two orders higher NaF concentration (110.0 mg.l-1) resulted in a strong increase of cells with chromosomal aberrations for all of indicators observed; e.g . 27.5% ABB . Based on literary sources, obtained results and properly experience in practical proceeding artificial fluoridation, the authors concluded that the latter is not adequate to the up-to-date status of knowledge . Besides of economical and technical problems, those scientific are mainly concerned with making doubtful the auto-presumed genotoxic inertness for chronic users of fluoridated drinking water . Author's opinion is that when necessarily provided, the artificial fluoridization of drinking water should be proceeded selectively (in accord with real requirements of an appropriated population group, its age structure and location), temporarily and with intermittent checkout of fluoridization application regimen . To conclude, authors recommend further observation with use of biological model situations in vivo.

Zh Mikrobiol Epidemiol Immunobiol, 1992, (9-10), 50 - 7
{Protection from virulent Salmonella groups B and D after the peroral immunization of chicks with a hybrid of Salmonella typhimurium and Salmonella dublin}; Polotskii IuE et al.; Chickens over 10 days old, infected orally with virulent salmonellae, were found to remain alive . Histologic investigation showed the development of mild enteritis and more pronounced, lasting for more than two weeks, inflammation of the cecum, dissemination and focal lesions in the liver (granulomas, necrosis) . In experiments on the oral immunization of 3-day old chickens the bivalent hybrid of S . typhimurium vaccine strain 274 and S . dublin induced only pronounced blast transformation in lymphatic follicles of the cecum, hyperplasia of activated macrophages and formation of granulomas from these macrophages and lymphocytes . After oral challenge of the immunized chickens with virulent salmonellae of group B (S . typhimurium) and group D (S . enteritidis, S . gallinarum-pullorum) the chickens exhibited sharply pronounced protection against adhesion, colonization and invasion, and a few penetrating bacteria were rapidly destroyed by immune macrophages . Hybrid strain 274/O9 proved to be suitable for use as oral bivalent vaccine against salmonellosis in chickens.

Yi Chuan Xue Bao, 1992, 19(4), 362 - 8
{Isolation of vitamin B2 auxotroph and preliminary genetic mapping in Salmonella typhimurium}; Wang A; The first independent vitamin B2 auxotrophs of Salmonella typhimurium were obtained by using selective medium containing extraordinarily high concentration of B2 (300 micrograms/ml) after mutagenesis . Transduction analysis showed that 21 B2 auxotrophs could be divided into four groups, which were unlinked to each other . It means that at least 4 structural genes were involved in B2 biosynthetic pathway . Preliminary genetic mapping indicated that 2 genes located in 7'-22' and other 2 located in 22'-34' and 61.5'-69' region on the genetic map of S . typhimurium respectively.

Zh Mikrobiol Epidemiol Immunobiol, 1992, (7-8), 42 - 5
{The evaluation of the mutagenic activity of pertussis vaccinal preparations}; Bolgareva GM et al.; Two vaccine preparations obtained from Bordetella pertussis, whole-cell vaccine constituting one of the components of adsorbed DPT vaccine and acellular vaccine, were tested for mutagenicity . The doses of the preparations covered the range 1-100 ED50 . Ames' test and the metaphase analysis of marrow cells of C57BL/6J mice were used . The acellular preparation was also tested on thymectomized mice, taking into consideration chromosomal aberrations in marrow metaphases . Whole-cell and acellular pertussis vaccines did not induce mutations in Salmonella typhimurium and chromosomal aberrations in mouse marrow cells.

Nutr Cancer, 1992, 17(3), 287 - 95
Antimutagenic and anticarcinogenic effects of carotenoids and dietary palm oil; Azuine MA et al.; Four carotenoids, canthaxanthin, beta-carotene, 8H-apo-beta-carotenal, and 8'-apo-beta-carotene methylester were tested for their ability to suppress the mutagenicity of 1-methyl-3-nitro-1-nitrosoguanidine and benzo{a}pyrene (BP) in Salmonella typhimurium tester strain TA 100 . The anticarcinogenic efficacy of the four carotenoids was further assessed in the BP-induced forestomach tumor model in female Swiss mice . The effect of dietary palm oil was also examined in BP-induced neoplasia in the female Haffkine Swiss mouse strain . Canthaxanthin, beta-carotene, 8'-apo-beta-carotenal, and 8'-apo-beta-carotene methylester showed a dose-dependent decrease in the mutagenicity compared with 1-methyl-3-nitro-1-nitrosoguanidine and BP in strain TA 100 . In the BP-induced forestomach tumor model, all four carotenoids showed a similar significant anticarcinogenic effect . Dietary administration of palm oil showed a dose-dependent antitumor activity in the animals . Our results show that the intrinsic antimutagenic and anticarcinogenic properties of the carotenoids are not significantly influenced by their conversion to vitamin A.

IARC Sci Publ, 1992, (116), 323 - 52
Chemicals classified by IARC: their potency in tests for carcinogenicity in rodents and their genotoxicity and acute toxicity; McGregor DB; Chemicals classified by the IARC to its groups 1, 2A, 2B and 3 were examined in an attempt to identify characteristics of their behaviour in experimental studies of carcinogenicity, genotoxicity and acute mammalian toxicity that correlate with those categories . Only those agents for which information on carcinogenic potency was available were studied . In both mice and rats, more chemicals were potent carcinogens if they had been categorized in Group 1 (human carcinogens) than if they had been put into one of the other categories . Not surprisingly, there was a weak association between carcinogenic potency and acute toxicity . Mice were especially sensitive to tumour induction by halides; the lower sensitivity of rats to any carcinogenic effect of halides could be due in part to their higher systemic toxicity in this species: a reduced differential of toxic and carcinogenic doses decreases the dose window in which carcinogenic effects may be demonstrated . It was notable that the human carcinogens were active in those genotoxicity tests with higher specificity for identifying rodent carcinogens . Predictive assays for carcinogenicity that were considered to be highly specific were tests for cytogenetic effects in vivo, unscheduled DNA synthesis in hepatocytes, mutation in any of the five commonly used strains of Salmonella typhimurium and mutation at the hprt locus in mammalian cells . None of the relationships was strong enough to form the basis of a simple categorization, but they could serve to alert investigators to chemicals of special toxicological interest and importance.

Ophthalmic Res, 1992, 24(3), 162 - 8
Retino-choroidal changes in endotoxin-induced uveitis in the rat; Ruiz-Moreno JM et al.; A single injection of 100 micrograms of lipopolysaccharide from Salmonella typhimurium in the foot pads of Lewis rats induced acute inflammation of the eye . Clinically, the disease started as early as 0.5 h and peaked 18 h after the inoculation . The aqueous protein concentration was increased after the inoculation . Histopathologically, cellular infiltrates and proteinaceous exudates were observed in the anterior segment (anterior chamber, iris and ciliary body) . In addition to those changes described in previous reports, the examination of the posterior segment showed retinal vasculitis, hemorrhagic exudates, focal destruction of photoreceptor cells and choroidal infiltration.

Microbiol Immunol, 1992, 36(4), 369 - 80
Bactericidal activities of rat defensins and synthetic rabbit defensins on Staphylococci, Klebsiella pneumoniae (Chedid, 277, and 8N3), Pseudomonas aeruginosa (mucoid and nonmucoid strains), Salmonella typhimurium (Ra, Rc, Rd, and Re of LPS mutants) and Escherichia coli; Kohashi O et al.; Rat defensins were purified and tested for in vitro bactericidal assay against gram-positive and gram-negative bacteria . Staphylococcus aureus (209P, Cowan I, Smith diffuse and Smith compact) were resistant to defensins, whereas Staphylococcus epidermidis, Staphylococcus saprophyticus, Micrococcus lysodeikticus and Bacillus subtilis were less sensitive . Gram-negative bacteria, such as Pseudomonas aeruginosa (mucoid and K) and Klebsiella pneumoniae (Chedid, 277, and 8N3 which were heavily capsulated, moderately capsulated and noncapsulated, respectively) were all very sensitive to defensins and killed within 20 min . Escherichia coli was moderately sensitive and the rough mutants of lipopolysaccharide (LPS) of Salmonella typhimurium LT2, such as Ra, Rc, Rd, and Re were equally sensitive to defensins, being killed within 40 min . Lysozyme did not show any bactericidal activity except against M . lysodeikticus and B . subtilis, whereas it enhanced the bactericidal activity of defensins against P . aeruginosa, E . coli, and K . pneumoniae and suppressed the killing activity of defensins against S . typhimurium and S . aureus . With regard to the three synthetic rabbit defensins, NP1, NP4, and NP5, NP1 showed strong bactericidal activity against K . pneumoniae 277, comparable to that of rat defensins . Neither NP4 nor NP5 showed any bactericidal activity, while NP5 rather enhanced the bactericidal activity of NP1 against K . pneumoniae 277.

Microbiol Immunol, 1992, 36(4), 339 - 50
Molecular cloning and nucleotide sequencing of a novel aminoglycoside 6'-N-acetyltransferase gene from an R-plasmid of Salmonella typhimurium S24 isolated in Taiwan; Peng CF et al.; A conjugative aminoglycoside resistance plasmid pST2 has been isolated from Escherichia coli K-12 14R525, which was mated with a clinical isolate of Salmonella typhimurium S24 . A novel resistance gene of aminoglycoside 6'-N-acetyltransferase{AAC(6')} was cloned from plasmid pST2 on a 1,393 kilobase (kb) of SphI-SalI fragment into vector pACYC184 and pUC18 . This novel AAC(6') gene in plasmid pST2 acetylated kanamycin, amikacin, dibekacin, tobramycin, gentamicin, netilmicin, and sisomicin . The complete nucleotide sequence of the novel AAC(6') gene and its neighboring sequences were also determined . Minicell experiments detected only one protein of 24.7 kilodaltons (kDa) translated from an open reading frame of the 618 base pairs (bp) gene.

Food Addit Contam, 1992 Jan-Feb, 9(1), 29 - 37
N-nitrosamine and mutagenicity formation in Chinese salted fish after digestion; Weng YM et al.; Salted and dried fish (Nemipterus virgatus), acquired from Hong Kong, was treated with 0.43-110 mM nitrite during in vitro digestion using gastric enzymes and the volatile N-nitrosamine content and mutagenicity on Salmonella typhimurium TA100 assayed without concentration . N-Nitrosodimethylamine (NDMA; the only nitrosamine detected) formation was second order in nitrite concentration . When 10 g of fish was treated with 6.96 mM nitrite, 394 nM NDMA was formed . Thiocyanate was catalytic for NDMA formation at nitrite concentration greater than 0.87 mM and when the ratio of thiocyanate to nitrite was greater than 1 . Approximately a 50% inhibition in NDMA formation by ascorbic acid was seen when the ratio of ascorbate to nitrite was approximately 2 or greater and the nitrite concentration was 1.74 mM . Mutagenicity increased with increasing nitrite concentration but the addition of thiocyanate did not increase mutagenicity over nitrite alone . Ascorbate increased mutagenicity even though NDMA formation was inhibited . Even at nitrite concentrations greater than 100-fold higher than expected in vivo, there was insufficient NDMA formed to account for the observed mutagenicity . These data do not exclude the possibility that the observed mutagenicity was due to non-volatile N-nitroso compounds, however, this possibility seems unlikely given the effects of ascorbate and thiocyanate which would be expected to inhibit and enhance non-volatile N-nitroso compound formation.

Environ Mol Mutagen, 1992, 20(3), 211 - 7
The role of glutathione in the bacterial mutagenicity of vapour phase dichloromethane; Dillon D et al.; Dichloromethane (DCM) vapour by inhalation is carcinogenic to rodents and is an in vivo rodent cell clastogen and a bacterial mutagen . It has been suggested that the bacterial mutagenicity of DCM is mediated by glutathione (GSH) conjugation . The involvement of endogenous and exogenous GSH in the conversion of DCM to a bacterial mutagen has been studied in a vapour phase protocol using wild-type and GSH-deficient (NG54; gsh) Salmonella typhimurium TA100 strains in the presence and absence of various rat liver fractions . The effect of the duration of exposure was also investigated in these Salmonella strains and in E . coli WP2 uvrA pKM101 . Dose- and time-related increases in revertants occurred with all metabolic activation systems used (without exogenous metabolic activation; with Aroclor-induced rat liver S9, microsomes, or cytosol fractions), with minor quantitative differences among the 3 strains . Mutagenicity was marginally highest in the presence of cytosol at the highest DCM concentrations . Strain NG54 gsh, which contains approximately 25% of the TA100 level of GSH/microgram protein, was slightly less responsive to DCM-induced mutagenicity than TA100 . Addition of 0.33 mumoles/plate of GSH had little effect on the mutagenic responses of TA100 or NG54 in the presence or absence of S9 . In these 2 strains, exogenous S9 produced small increases in mutagenicity at the highest concentrations of DCM (2 and 4% v/v) . These results suggest that if an interaction between DCM and GSH is required for the activation of DCM to a bacterial mutagen, it occurs at low levels of endogenous GSH and is not significantly affected by GSH supplementation.

Environ Mol Mutagen, 1992, 20(3), 188 - 98
Evaluation of the mutagenicity of an N-nitroso contaminant of the sunscreen Padimate O: N-nitroso-N-methyl-p-aminobenzoic acid, 2-ethylhexyl ester (NPABAO); Dunkel VC et al.; The nitrosamine contaminant, N-nitroso-N-methyl-p-aminobenzoic acid, 2-ethylhexyl ester (NPABAO), of the major sunscreen ingredient Padimate O (4-N,N'-dimethylamino-benzoic acid, 2-ethylhexyl ester) was synthesized and tested for mutagenicity in the Salmonella typhimurium and mouse lymphoma L5178Y TK +/- assays . In contrast to the previously reported positive responses in S . typhimurium tester strains TA100 and TA1535 {Loeppky et al., 1991}, there were no increases in the number of revertants with strains TA98, TA100, TA1535, and TA1538 in either the Salmonella plate incorporation {Ames et al., 1975} or preincubation {Yahagi et al., 1977} assays . Additional testing with Salmonella, following the modified preincubation procedure {Rogan, 1990} that gave the initial positive response, was also negative . Data from the mouse lymphoma assays were also uniformly negative . During synthesis of NPABAO, small amounts of 4-N,N'-dimethylamino-3-nitrobenzoic acid, 2-ethylhexyl ester (DMANBAO) can be formed . To determine whether the reported positive mutagenicity response of NPABAO could be the result of trace amounts of DMANBAO in the NPABAO, that compound was also synthesized and tested for mutagenicity with Salmonella . Positive responses were obtained with tester strains TA98 and TA 1538 but not with TA100 and TA1535, indicating that DMANBAO was not responsible for the increase in revertants originally reported.

Mutat Res, 1992, 280(3), 161 - 8
Effects of supercypermethrin, a synthetic developmental pyrethroid, on four biological test systems; Miadokova E et al.; The genotoxic potential of the insecticide supercypermethrin, a second-generation pyrethroid, was studied on four different test systems . It was non-mutagenic to Salmonella typhimurium strains TA1535, TA100, TA1538, TA98 and TA97 in the presence and absence of S9 mixture . It induced gene conversion at the tryptophan locus and induced point mutations at the isoleucine locus in Saccharomyces cerevisiae cells . A slight increase in the frequency of aberrant anaphases and telophases in root tips of Hordeum vulgare and Vicia faba was observed, but no genotoxic effects were detected in Drosophila melanogaster.

Environ Mol Mutagen, 1992, 20(1), 61 - 72
Comparison of acyltransferase-mediated mutagenicity and nucleic acid binding of N-acetoxy-4-acetylaminobiphenyl by hepatic and bladder microsomes from rats and dogs; Swaminathan S et al.; Acyltransferase-mediated mutagenic and metabolic activation of N-acetoxy-4-acetylaminobiphenyl (N-OAc-AABP) by hepatic tissues of rats and dogs were compared . N-OAc-AABP was mutagenic in Salmonella typhimurium TA98 even in the absence of exogenous enzyme(s) . However, supplementation with hepatic microsomes from dogs showed a dose-dependent increase in mutagenicity of N-OAc-AABP, whereas under the same conditions, rat microsomes were inactive . Incubation of liver microsomes with RNA showed that 46.4 and 11.2 nmole of {3H}N-OAc-AABP were bound/mg RNA/mg protein with dogs and rats, respectively . The hepatic microsome-mediated binding and mutagenicities of N-OAc-AABP were blocked by paraoxon, suggesting the involvement of deacetylase(s) in the activation process . Analyses of the in vitro incubates of N-OAc-AABP with rat and dog liver microsomes revealed the O-deacetylation product N-hydroxy-4-acetylaminobiphenyl (N-OH-AABP) as the major metabolite . The ratios of O-deacetylation of N-O{14C}Ac-AABP versus N-deacetylation of N-OAc-{14C}AABP for hepatic microsomes from dogs and rats were 2.9 and 7.2, respectively . The O- and N-deacetylases are also distributed in bladder tissues and their activities in comparison to the hepatic tissues were lower and amounted to 14.2 and 5.0 nmoles (O/N-deacetylation ratio 2.8) for dogs and 14.8 and 1.7 nmoles per mg protein per min (O/N-ratio of 8.7) for rats . The microsomes from bladder tissues also catalyzed the binding of {3H}N-OAc-AABP to RNA and enhanced its mutagenic response in TA98, both of which were blocked by paraoxon . The occurrence of deacetylase(s) in the target tissues of the bladder carcinogen 4-acetylaminobiphenyl (AABP) suggests that metabolic activation of some of the proximate metabolites could occur within these target organs . Furthermore, since the O-deacetylation product N-OH-AABP is relatively innocuous compared to the N-deacetylation product N-acetoxy-4-aminobiphenyl, these results imply that the refractiveness of rats for 4-aminobiphenyl or AABP-induced bladder carcinogenesis might in part be associated with the higher ratios of microsomal O/N-deacetylase activities . Thus susceptibility to arylamine or arylacetamide-induced liver and bladder carcinogenesis might be influenced by the microsomal deacetylases.

Vaccine, 1992, 10(6), 405 - 11
Synthetic recombinant vaccine expressing influenza haemagglutinin epitope in Salmonella flagellin leads to partial protection in mice; McEwen J et al.; The influenza virus haemagglutinin epitope 91-108, which is a conserved amino acid sequence in all type A H3 strains, was expressed in Salmonella flagellin, to evaluate its potential as a vaccine . For that purpose, a synthetic oligonucleotide comprising 54 bases coding for the corresponding sequence was inserted into the plasmid pLS408 and transformed into Escherichia coli JM101 . Colonies containing the recombinant plasmid were used to transform Salmonella typhimurium LB5000 and were then transduced to a flagellin negative 'live vaccine' aroA mutant of Salmonella dublin . Rabbits immunized either with the live recombinant S . dublin or with the flagellin isolated from it, showed significant levels of IgG response against the synthetic peptide 91-108 as well as against the intact A/Texas/77 influenza virus . Mice immunized with the same preparations developed influenza-specific IgG antibodies in the blood and secreted IgA antibodies in their lungs . Furthermore, these mice showed about 50% protection against challenge infection with the virus . The most successful results were achieved by intranasal immunization with the isolated recombinant flagellin, when employed without the aid of adjuvant.

Mutat Res, 1992 Jan, 281(1), 55 - 61
Genotoxicity and cell proliferative activity of a nitrosated Oroxylum indicum Vent fraction in the pyloric mucosa of rat stomach; Tepsuwan A et al.; In vivo genotoxic activity and cell proliferative activity were examined in the stomach mucosa of male F344 rats by in vivo short-term methods after oral administration of a nitrosated Oroxylum indicum Vent (OiV) fraction, which had been found to be mutagenic without S9 mix to Salmonella typhimurium TA98 and TA100 . Administration of the nitrosated OiV fraction at doses of 1 and 2 g/kg body weight induced dose-dependent DNA single-strand scission (p less than 0.02), determined by the alkaline elution method, in the stomach pyloric mucosa 2 h after its administration: a dose of 2 g/kg body weight induced an 18-fold increase in the DNA elution rate constant . Administration of the nitrosated OiV fraction at doses of 0.7-2.8 g/kg body weight also induced dose-dependent increases, up to 11-fold (p less than 0.05), in replicative DNA synthesis in the stomach pyloric mucosa 16 h after its administration . Moreover administration of the nitrosated OiV fraction at doses of 0.25-2.0 g/kg body weight induced dose-dependent increases, up to 100-fold, in ornithine decarboxylase activity in the stomach pyloric mucosa with a maximum 4 h after its administration . These results demonstrate that the nitrosated OiV fraction has genotoxic and cell proliferative activity in the pyloric mucosa of rat stomach in vivo.

J Bacteriol, 1992 Jan, 174(1), 336 - 41
Characterization of lipopolysaccharide fractions and their interactions with cells and model membranes; Yeh HY et al.; The role of the length of the O-antigen polysaccharide side chain of bacterial lipopolysaccharide (LPS) in biological and model membrane systems was investigated . LPS from Salmonella typhimurium ATCC 14028 was chromatographed on a Sephadex G-200 column in the presence of sodium deoxycholate and separated into three fractions on the basis of molecular size . Sodium dodecyl sulfate-polyacrylamide gel electrophoresis, Western blot (immunoblot), and chemical analyses indicated that these fractions differed from each other primarily in the number of repeating units in the O-antigen polysaccharide side chain . In a biological system fractions 2 and 3 had the same effects to induce mitogenesis in murine lymphocytes, but fraction 1 was less effective than the other two fractions . In a model membrane system, LPS induced changes in small unilamellar vesicles (SUVs) which were measured by changes in the behavior of a fluorescent probe, 1,6-diphenylhexa-1,3,5-triene (DPH), and interaction of increasing amounts of all LPS fractions with SUVs gradually increased DPH anisotropy . Fractions 2 and 3 had similar effects on the SUVs as detected by changes in DPH anisotropy, while fraction 1 had almost twice as much activity as the other two fractions . These results suggest that the polysaccharide side chain of LPS may modulate the ability of biologically active lipid A to interact with cells and model membranes . In addition, factors other than changes in membrane fluidity may play a role in mediating LPS-induced cell activation.

Mutat Res, 1992 Jan, 265(1), 61 - 73
Structural requirements for the induction of the SOS repair in bacteria by nitrated polycyclic aromatic hydrocarbons and related chemicals; Mersch-Sundermann V et al.; The CASE (computer-automated structure evaluation) methodology was used to investigate the structural basis of the SOS-inducing activity of 56 nitrated polycyclic aromatic hydrocarbons (nitroarenes, nPAH) and the unsubstituted parent PAH molecules . Based upon the presence and/or absence of structural features, CASE identified 5 activating (biophores) and 4 inactivating (biophobes) fragments responsible for the SOS-inducing activity . Based upon these fragments, CASE correctly calculated the genotoxicity of 94.6% of the molecules in the training set (sensitivity = 0.85, specificity = 1.0) . Disregarding the questionable experimental results of the unexpected very weak direct-acting activity of the unsubstituted benzo{a}pyrene, dibenzo{a,h}anthracene and 7,12-dimethylbenz{a}anthracene, the concordance of the prediction was 100%, i.e., sensitivity = 1.0, specificity = 1.0 . Additionally, the quantitative analysis of the SOS-inducing potency showed a good correlation between the experimental and predicted results . The present analyses indicate an identity in the structural determinants responsible for SOS induction in E . coli PQ37 (SOS chromotest) and mutagenicity in Salmonella typhimurium.

Mutat Res, 1992 Jan-Mar, 276(1-2), 93 - 100
Results of a comparative study on the Salmonella pre-incubation and plate incorporation assays using test samples from the IPCS collaborative study; Goto S et al.; Three complex mixtures (air particles, diesel particles and a coal tar fraction) and two pure compounds (benzo{a}pyrene and 1-nitropyrene) were tested in both the pre-incubation and the plate incorporation assay employing Salmonella typhimurium TA98 and TA100 . Each experiment was conducted independently 2 or 4 times in duplicate in the presence and absence of metabolic activation . The mutagenic activities were calculated by least squares linear regression from the slope of the linear portion of each dose-response curve . Although slightly higher mutagenic activity was observed in the pre-incubation assay for the two pure compounds and with the plate incorporation assay for the diesel particulate sample, the overall data from both assays gave similar values and good correlations in TA100 and TA98 . The results indicate that the pre-incubation assay could be used for these samples instead of the plate incorporation assay.

Mutat Res, 1992 Jan-Mar, 276(1-2), 3 - 9
Design and implementation of a collaborative study of the mutagenicity of complex mixtures in Salmonella typhimurium; Lewtas J et al.; In 1987, the International Programme on Chemical Safety (IPCS) in collaboration with the U.S . Environmental Protection Agency (U.S . EPA) and the U.S . National Institute of Standards and Technology (U.S . NIST) initiated an international collaborative study of the mutagenicity of complex environmental mixtures in the Ames Salmonella typhimurium mutation assay . The objectives of this study were: (1) to estimate the inter- and intra-laboratory variability associated with the extraction of mixtures for bioassay, (2) to estimate the inter- and intra-laboratory variability associated with the Salmonella typhimurium bioassay when applied to complex mixtures, and (3) to determine whether standard reference complex mixtures would be useful in mutagenicity studies and to evaluate whether reference or certified mutagenicity values determined from this collaborative study should be reported . The complex mixtures used in this study were selected from standard reference materials (SRMs) which had previously been issued by the U.S . NIST as SRM 1597 (coal tar), SRM 1649 (diesel particulate matter) and SRM 1650 (urban air particulate matter) with certified values for polycyclic aromatic hydrocarbons . These SRM complex mixtures are available to scientists as reference standards for analytical chemistry research and are under consideration as SRMs for mutagenicity studies of complex environmental mixtures . This paper briefly describes the final study design, protocol, selection of the complex mixtures, and implementation of this international study.

Mutat Res, 1992 Jan-Mar, 276(1-2), 101 - 15
Mutagenicity and chemical analysis of sequential organic extracts of airborne particulates; Savard S et al.; To obtain insight into the identity of chemicals associated with the mutagenicity of United States National Institute of Standards and Technology (NIST) Standard Reference Materials SRM 1649 (urban dust) and SRM 1650 (diesel particulate), parallel mutagenicity tests and chemical analyses were performed on dichloromethane and sequential organic extracts of these samples . SRM 1649 and 1650 were sequentially extracted with five organic solvents of increasing polarity, in order to partition mutagenic components into discrete fractions . The solvents (with associated polarity index) were as follows: (1) hexane (0.0); (2) hexane:diethyl ether 9:1 (0.29); (3) hexane:diethyl ether 1:1 (1.45); (4) diethyl ether (2.9); (5) methanol (6.6) . 0.9270 g of SRM 1649, and 0.0510 g of SRM 1650 were each extracted three times with 8 ml of each of the solvents, the three aliquots were pooled, and analysed for target organics or solvent-exchanged into DMSO for mutagenicity testing in Salmonella typhimurium strains TA98 and TA100 . The dichloromethane extracts of SRM 1649 and SRM 1650 contained direct-acting mutagens in Salmonella strains TA98 and TA100; SRM 1650 was significantly more potent than SRM 1649 in either strain . Addition of S9 caused a large decrease in mutagenicity of each extract, although SRM 1650 remained more potent . An interesting pattern of mutagenicity was observed for the sequential extracts of SRM 1649 and SRM 1650: the mutagenic potency of SRM 1649 extracts increased with increasing polarity of the extraction solvent while the response of the SRM 1650 extracts was the opposite . This suggests that the direct-acting mutagens in SRM 1650 are unlike those in SRM 1649 . The response, though diminished, was largely unchanged when S9 was included in the test mixture . Chemical analyses on the various extracts were performed using a Hewlett-Packard model 5890 gas chromatograph equipped with a model 5970B mass selective detector (GC-MSD), and a 0.3 microns film thickness cross-linked methyl silicone capillary column (HP 1909A-101) . Selected ion monitoring (SIM) methods were used to analyze for 105 target compounds including PAHs and nitro-PAHs . Chemical analysis of the dichloromethane extracts of SRM 1649 and SRM 1650 identified three main classes of compounds: polyaromatic hydrocarbons (PAH), nitro-polyaromatic hydrocarbons (NO2-PAHs) and heterocyclics . The concentration of target compounds and the proportion of nitro-PAHs and heterocyclic compounds were considerably greater in SRM 1650 than in SRM 1649, consistent with the observed differences in their mutagenic potency . However, the different responses of the dichloromethane extracts in TA98 and TA100 suggest the presence of different (unidentified) compounds.(ABSTRACT TRUNCATED AT 400 WORDS)

Microbiol Immunol, 1992, 36(6), 593 - 602
Type 1 pili enhance the invasion of Salmonella braenderup and Salmonella typhimurium to HeLa cells; Horiuchi S et al.; The relationship between type 1 pili-associated adhesion and invasion to HeLa cells by Salmonella braenderup and S . typhimurium was studied . When the clinical isolates of these strains were grown in L-broth, they showed both type 1 pili formation and mannose-sensitive adhesion to HeLa cells . On the other hand, the type 1 pili-defective mutants, which were obtained either by repeated subcultures on L-agar plates or by the transposon Tn1-insertion mutagenesis of the S . braenderup and S . typhimurium strains, concomitantly lost mannose-sensitive adhesion to HeLa cells . When the HeLa cells were incubated with Salmonella, the type 1 piliated strains invaded the HeLa cells with much higher infection rate than did the type 1 pili-defective strains . The invasion of type 1 piliated strains to HeLa cells was markedly inhibited in the presence of D-mannose . The infectivity of the strain, which lost type 1 pili but still had mannose-resistant adhesion, was slightly higher than that of the strains defective in both mannose-sensitive and mannose-resistant adhesion . These results suggested that type 1 pili have a role in enhancing the invasion of S . braenderup and S . typhimurium to HeLa cells.

Acta Virol, 1992 Jan, 36(1), 25 - 31
Dynamics of non-specific antibacterial activity of the peritoneal cells of mice induced with Coxiella burnetii antigen; Tokarevich NK et al.; It was found that primary immunization with Coxiella burnetii antigen increased mouse resistance to Salmonella typhimurium infection as evidenced by acceleration of bacterial elimination from the peritoneal cavity and a decrease in lethality of experimental animals . The existence of two rises of bactericidal activity of mouse peritoneal cells was ascertained: the "early" on days 1 and 2, and the "late" on day 14 after C . burnetii administration . The first rise was accompanied by some increase in the number of peritoneal cells as well as by some change of their qualitative representation . The second increase of antibacterial activity was detected during the pronounced cellular and humoral immune responses to C . burnetii.

J Med, 1992, 23(5), 327 - 38
Effects of tetanus toxin, Salmonella typhimurium porin, and bacterial lipopolysaccharide on platelet aggregation; Matera C et al.; Endotoxins may interfere with platelet aggregation by interacting with the platelet membrane . The aim of this study was to evaluate the effects of tetanus toxin, Salmonella typhimurium porin, and bacterial lipopolysaccharide (LPS) on platelet aggregation induced by ADP and thrombin in vitro . Spontaneous platelet aggregation and platelet aggregation induced by ADP and thrombin were measured . Our results show that Salmonella typhimurium porin and bacterial LPS enhanced human and rabbit platelet aggregation induced by ADP and thrombin . Tetanus toxin did not affect platelet aggregation.

Vaccine, 1992, 10(12), 811 - 3
Active protection of mice against Salmonella typhi by immunization with strain-specific porins; Isibasi A et al.; NIH mice were immunized with between 2.5 and 30 micrograms of two highly purified porins, 34 kDa and 36 kDa, isolated from the virulent strain Salmonella typhi 9,12, Vi:d . Of mice immunized with 10 micrograms of porins, 90% were protected against a challenge with up to 500 LD50 (50% lethal doses) of S . typhi 9,12,Vi:d and only 30% protection was observed in mice immunized with the same dose of porins but challenged with the heterologous strain Salmonella typhimurium . These results demonstrate the utility of porins for the induction of a protective status against S . typhi in mice.

Environ Mol Mutagen, 1992, 20(4), 289 - 96
Certain tryptophan photoproducts are inhibitors of cytochrome P450-dependent mutagenicity; Rannug U et al.; Two photoproducts, derived from UV-irradiation of the amino acid L-tryptophan and with high Ah (TCDD) receptor binding affinity, were tested for genotoxic and antimutagenic effects . The two indolo{3,2-b}carbazole derivatives, with the molecular weights of 284 and 312, respectively, were tested in Saccharomyces cerevisiae strain D7 for mitotic gene conversion and reverse mutation and in strain RS112 for sister chromatid conversion and gene conversion . No significant (P > 0.05) genotoxic effects were found in strain D7, while strain RS112 showed a small but significant increase in the frequency of sister chromatid conversions . In Chinese hamster ovary (CHO) cells the two compounds induced a statistically significant but less than twofold increase in the frequency of sister chromatid exchanges (SCE) . No mutations were detected when the compounds were tested in Salmonella typhimurium strains TA98 and TA100 . However, both 284 and 312 acted as antimutagens on strain TA100 + S9 in the presence of benzo(a)pyrene . The decrease in mutagenicity by the most potent compound 284 was 20 revertants/nmol . This effect could be explained by an inhibitory effect on the cytochrome P450-dependent ethoxyresorufin O-deethylase (EROD) activity as seen in rat hepatocytes . The two compounds were also tested with hamster cells expressing rat cytochrome P-450IA1 . The results support the conclusion that this cytochrome P-450 isozyme is inhibited by the tryptophan photoproducts . Similar results were also seen with two other high affinity Ah receptor ligands the quinazolinocarboline alkaloids rutaecarpine and dehydrorutaecarpine.

Microbiol Immunol, 1992, 36(3), 269 - 78
The comparison of cell-mediated immunity induced by immunization with porin, viable cells and killed cells of Salmonella typhimurium; Matsui K et al.; A marked level of cell-mediated immunity (CMI) to Salmonella typhimurium-infection in mice, as determined by acquired resistance, delayed-type hypersensitivity, interleukin-2 production and interferon-gamma production, was induced by immunization with porin or viable cells but not with killed cells of S . typhimurium LT2 . When the up-regulation of immune system to each immunogen was studied by comparing increases of Ia-bearing macrophages, the immunization with porin or viable cells, but not killed cells, could stimulate the immune system for more than 14 days . Interleukin-1 (IL-1) production of macrophages to each immunogen was also examined; the result showed that immunization with porin or viable cells could induce a notable level of IL-1 production, while killed cells could not . However, when the abilities to induce these immune responses were compared between UV-killed and heat-killed cells, UV-killed cells were superior to heat-killed cells . These results suggested that the ineffectiveness of immunogen that lacked CMI-inducing ability might be ascribed to the denaturation of antigen and the insufficient inductions of Ia-bearing macrophages and IL-1 production.

Environ Mol Mutagen, 1992, 19(3), 185 - 94
Mutations in topA interfere with the inducible expression of DNA damage response loci in Salmonella typhimurium; Smith CM et al.; Strains of Salmonella typhimurium deficient in topoisomerase I activity (topA mutants) are UV sensitive and non-mutable (Overbye and Margolin: J Bacteriol 146:170-178, 1981) . Using lac-operon fusions to DNA damage inducible (din) loci we investigated whether these observations could be explained by an inability of topA strains to efficiently induce DNA damage responses . Mitomycin C (MMC)-induced expression of lac-operon fusions to uvrB and to a second SOS locus, din-9, was largely eliminated in topA bacteria . The inducible expression of several other din-fusions was also diminished . This inducibility defect was mimicked by growth of din-9 topA+ bacteria in media of high osmolarity, a condition that leads to increased DNA supercoiling . Inhibitors of DNA gyrase efficiently induced din-9 in topA bacteria . Together, these results suggest that the topA effect on din expression may be mediated at the level of DNA supercoiling . The sensitivities of a number of din-fusions to topA paralleled the degree to which they were repressed by excess LexA, suggesting that mutations in topA might influence LexA-operator interactions and/or increase lexA expression.

Environ Mol Mutagen, 1992, 19(2), 156 - 60
Nitrobenzo{a}pyrene-induced DNA amplification in SV40-transformed Chinese hamster embryo cells; Neft RE et al.; Nitrobenzo{a}pyrenes (NBaPs) are ubiquitous environmental pollutants that produce mutations in Salmonella typhimurium and Chinese hamster ovary cells . In this study, 1-, 3-, and 6-NBaP induced amplification of SV40 DNA sequences in an SV40-transformed Chinese hamster embryo cell line which is sensitive to DNA amplification by various known carcinogens . Of the three isomers, 3-NBaP produced the highest level of gene amplification, which was 4.8 relative to untreated controls at a dose of 5 micrograms/ml . Considering the relationship between gene amplification and tumorigenesis, it seems prudent to carry out a more exhaustive analysis of the carcinogenic potential of these agents.

J Bacteriol, 1992 Jan, 174(1), 245 - 53
A method for constructing single-copy lac fusions in Salmonella typhimurium and its application to the hemA-prfA operon; Elliott T; This report describes a set of Escherichia coli and Salmonella typhimurium strains that permits the reversible transfer of lac fusions between a plasmid and either bacterial chromosome . The system relies on homologous recombination in an E . coli recD host for transfer from plasmid to chromosome . This E . coli strain carries the S . typhimurium put operon inserted into trp, and the resulting fusions are of the form trp::put::{Kanr-X-lac}, where X is the promoter or gene fragment under study . The put homology flanks the lac fusion segment, so that fusions can be transduced into S . typhimurium, replacing the resident put operon . Subsequent transduction into an S . typhimurium strain with a large chromosomal deletion covering put allows selection for recombinants that inherit the fusion on a plasmid . A transposable version of the put operon was constructed and used to direct lac fusions to novel locations, including the F plasmid and the ara locus . Transductional crosses between strains with fusions bearing different segments of the hemA-prfA operon were used to determine the contribution of the hemA promoter region to expression of the prfA gene and other genes downstream of hemA in S . typhimurium.

Arch Biochem Biophys, 1992 Jan, 292(1), 179 - 89
Reaction of the nucleotide analogue 2-{(4-bromo-2,3-dioxobutyl)thio}adenosine 2',5'-bisphosphate at the coenzyme site of wild-type and mutant NADP(+)-specific glutamate dehydrogenases from Salmonella typhimurium; Haeffner-Gormley L et al.; Wild-type glutamate dehydrogenase (EC 1.4.1.4) from Salmonella typhimurium reacts at 25 degrees C in 0.1 M phosphate buffer, pH 7, with the nucleotide analogue 2-{(4-bromo-2,3-dioxobutyl)thio}-adenosine 2',5'-bisphosphate (2-BDB-TA 2',5'-DP) to give 78% inactivation . Protection against inactivation was achieved with NADPH, indicating that modification occurred in the region of the coenzyme binding site . After reaction of the enzyme with 2-BDB-TA 2',5'-DP, the dioxo moiety of the bound reagent was reduced with {3H}NaBH4 . The radioactive peptide which corresponds to the sequence Leu282-Cys283-Glu284-Ile285-Lys286 was isolated by HPLC from tryptic digests of inactive modified enzyme but was absent in digests of active enzyme modified in the presence of NADPH . Mutant enzyme E284Q was 64% inactived by 2-BDB-TA 2',5'-DP and modification of the corresponding Leu282-Lys286 peptide was found, while neither mutant enzyme C283I nor C283I:E284Q was inactivated by the nucleotide analogue and no corresponding radioactive peptides were found . These results show that cysteine-283 is the target of the reagent and is located near the coenzyme binding site . The nucleotide analogue 2-{(4-bromo-2,3-dioxobutyl)thio}-1,N6-ethenoadenosine 2',5'-bisphosphate (2-BDB-T epsilon A 2',5'-DP) has also been shown to react with cysteine-283 (L . Haeffner-Gormley et al., 1991, J . Biol . Chem . 266, 5388-5394) . However, the predominant form of the Leu282-Lys286 peptide after reaction with 2-BDB-TA 2',5'-DP contained only 0.17 mol tritium/mol leucine, whereas the 2-BDB-T epsilon A 2',5'-DP-modified peptide contained 1.80 mol tritium/mol leucine; these results indicate that the reaction product of 2-BDB-T epsilon A 2',5'-DP retains two reducible carbonyl groups while these are not available in the product of 2-BDB-TA 2',5'-DP . It is suggested that cysteine-283 reacts primarily at a carbonyl group of 2-BDB-TA 2',5'-DP to form a thiohemiacetal derivative, while it reacts at the methylene group of 2-BDB-T epsilon A 2',5'-DP with displacement of bromide . Both nucleotide analogues also yielded, in small amount, a crosslinked peptide containing the sequences 282-286 and 299-333, indicating proximity between these regions in the native structure.

Int J Tissue React, 1992, 14(5), 211 - 8
Butylated hydroxyanisole produces both mutagenic and desmutagenic derivatives under gastric conditions; Kanazawa K et al.; Dietary butylated hydroxyanisole (BHA) has been known to have inconsistent functions on carcinogenesis, both prevention and initiation . We assumed that both functions of BHA were introduced by the derivatives formed after the reaction with gastric components such as nitrite in the stomach . We then identified the derivatives produced by incubating BHA with sodium nitrite at pH 2.0 or pH 5.0 . Eight derivatives were detected; 2-tert.-butyl-p-quinone (BQ), 3,3'-di-tert.-butyl-biphenyldiquinone-(2,5,2',5') (BBDQ), 2,6-di-tert.-butyl-8-hydroxy-dibenzofuran-1,4-quinone (BHDQ), 6-nitro-BHA, 2,2'-dihydroxy-3,3'-di-tert.-butyl-5,5'-dimethoxy-biphenyl (di-BHA), an oxidized product of di-BHA, and two unstable reaction intermediates . BQ was a major final product at pH 2.0, but not at pH 5.0 . 6-Nitro-BHA and the oxidized products of di-BHA were also the final products . BBDQ was formed from di-BHA and easily converted to BHDQ . Their mutagenicity and desmutagenicity were assayed using Salmonella typhimurium strains . BQ and BBDQ were the mutagens of base-substitution type, BHDQ was the potent desmutagen against a mutagenicity of Trp-P-2, and the others had neither of the two activities . Thus, BHA was found to produce both the mutagen and desmutagen under the gastric conditions . BQ has been previously reported to be easily detoxified by glutathione, and BHA itself is well known to prevent carcinogenesis . In the assessment of dietary BHA on carcinogenesis, since one of the mutagens from BHA is easily detoxified in our bodies and another is converted to a desmutagen, BHA appears to be one of the favourable chemicals for us.

J Am Vet Med Assoc, 1991 Dec 15, 199(12), 1757 - 9
Salmonella typhimurium abscess as a postoperative complication in a horse with colic; Blikslager AT et al.; An 11-year-old, 430-kg fox-trotter stallion was referred for evaluation of colic . A right-sided inguinal hernia was diagnosed . At exploratory laparotomy, the ileum was found to be herniated through the right inguinal canal . Compromised small intestine was resected, jejunocecal anastomosis was performed, and the horse was castrated . Three days after surgery, the stallion would not bear weight on the left hind limb . The musculature of the left thigh region became swollen . Aspiration of the left thigh region yielded serosanguineous fluid from which Salmonella typhimurium was isolated . Ultrasonography of the left thigh revealed multiple hypoechoic areas suggestive of abscess . The left medial thigh region was surgically incised, and a large abscess was drained . Bacteriologic culture of feces yielded S typhimurium . The owner elected to have the horse euthanatized.

Proc Natl Acad Sci U S A, 1991 Dec 15, 88(24), 11470 - 4
Intracellular replication is essential for the virulence of Salmonella typhimurium; Leung KY et al.; Salmonella typhimurium is a facultative intracellular parasite, capable of penetrating, surviving, and multiplying within diverse eukaryotic cell types, including epithelial and phagocytic cells . We have been studying intracellular replication of S . typhimurium and found that it is essential in the pathogenesis of this bacterium . A total of 45,000 independent mini-Mu MudJ transposon mutants in S . typhimurium SL1344 were screened in Madin-Darby canine kidney (MDCK) epithelial cells with a beta-lactam, cefotaxime, to enrich for mutants defective for intracellular replication . Ten different auxotrophic (purine, pyrimidine, purine/methionine, and valine/isoleucine) and three prototrophic replication-defective mutants (Rep-) were identified . All Rep- mutants showed no differences in aerobic and anaerobic growth patterns, motility, serum sensitivity, mouse macrophage survival, iron uptake, and phosphate requirements . All Rep- mutants were unable to multiply inside MDCK, HeLa, and Caco-2 epithelial cells . When required nutrients for various auxotrophs were supplemented, auxotrophs then replicated inside MDCK cells . Although the parental strain multiplies in large vacuoles inside MDCK cells that distort the host cells, MDCK cells infected with the Rep- mutants appeared relatively normal and few bacteria were seen inside vacuoles . The purine auxotrophs and the three prototrophic Rep- mutants were highly attenuated in mice, and oral and intraperitoneal LD50 levels were 3 to 4 orders of magnitude higher than the wild type level . The three prototrophs were invasive and persisted in the murine organs such as livers and spleens for at least 3 weeks . Therefore, these prototrophic genes are needed for intracellular replication and are essential to the virulence of S . typhimurium.

J Biol Chem, 1991 Dec 15, 266(35), 23893 - 9
Crystal structure of the lysine-, arginine-, ornithine-binding protein (LAO) from Salmonella typhimurium at 2.7-A resolution; Kang CH et al.; A wide variety of sugars, amino acids, peptides, and inorganic ions are transported into bacteria by periplasmic transport systems consisting of substrate-specific receptors (binding proteins) and membrane-bound protein complexes . The crystal structure of the lysine-, arginine-, ornithine-binding protein (LAO) at 2.7-A resolution shows that the molecule has a bi-lobal structure and that its topological structure is different from other amino acid-binding proteins but is similar to the sulfate-binding protein and maltose-binding protein . High sequence homology between LAO and the histidine-binding protein (HisJ) and the fact that LAO and HisJ share the same membrane-bound protein complex allow one to define functional regions responsible for the ligand binding and for the interaction with the membrane complex.

Science, 1991 Nov 29, 254(5036), 1342 - 7
Three-dimensional structures of the ligand-binding domain of the bacterial aspartate receptor with and without a ligand; Milburn MV et al.; The three-dimensional structure of an active, disulfide cross-linked dimer of the ligand-binding domain of the Salmonella typhimurium aspartate receptor and that of an aspartate complex have been determined by x-ray crystallographic methods at 2.4 and 2.0 angstrom (A) resolution, respectively . A single subunit is a four-alpha-helix bundle with two long amino-terminal and carboxyl-terminal helices and two shorter helices that form a cylinder 20 A in diameter and more than 70 A long . The two subunits in the disulfide-bonded dimer are related by a crystallographic twofold axis in the apo structure, but by a noncrystallographic twofold axis in the aspartate complex structure . The latter structure reveals that the ligand binding site is located more than 60 A from the presumed membrane surface and is at the interface of the two subunits . Aspartate binds between two alpha helices from one subunit and one alpha helix from the other in a highly charged pocket formed by three arginines . The comparison of the apo and aspartate complex structures shows only small structural changes in the individual subunits, except for one loop region that is disordered, but the subunits appear to change orientation relative to each other . The structures of the two forms of this protein provide a step toward understanding the mechanisms of transmembrane signaling.

J Biol Chem, 1991 Dec 5, 266(34), 23215 - 25
Epitope mapping of four monoclonal antibodies recognizing the hexose core domain of Salmonella lipopolysaccharide; Luk JM et al.; Four murine monoclonal antibodies reactive with distinctive regions of the hexose core domain of Salmonella lipopolysaccharide (LPS) were generated and their epitope specificities were delineated . MAST 56 (IgG1) and MAST 50 (IgG3) antibodies elicited by immunizations with Salmonella typhimurium Rb1 and Rb2 mutants, reacted selectively in enzyme immunoassay with the LPS from rough mutants . In contrast, MATy 1 (IgM) and MATy 2 (IgG2b) antibodies raised by an attenuated Salmonella typhi 620 Ty strain were reactive with LPS from both smooth and rough Salmonellae . Immunoblotting analysis showed that MATy 1 distinguished only the bottom bands (naked LPS core) among the heterogeneous LPS populations, whereas MATy 2 gave a ladder pattern (reactive with both naked and O-chain-substituted LPS cores) . Differential binding specificities of MATy 1 and MATy 2 antibodies to the naked and capped LPS cores were further analyzed utilizing S . typhimurium polysaccharide fractions with different O-chain:core ratios which were obtained after separation by Sephacryl S-200 chromatography . Steric effects on the antibody reactivity by the bulky O-polysaccharide chain were detected . The use of chemically defined native and synthetic saccharides as inhibitors, in combination with the conformation of the Salmonella core oligosaccharide, permitted the definition of antigenic determinants carried in the core domain recognized by each antibody: (i) the branches I and VIII are essential for MATy 1 recognition, (ii) the backbone III-IV-V for MATy 2, (iii) the backbone II-III-IV-V for MAST 56, and (iv) the backbone plus the branch III-IV-V-VIII for MAST 50 . (formula; see text)

Biochim Biophys Acta, 1991 Dec 2, 1129(1), 115 - 8
Cloning and sequence analysis of hydrogenase regulatory genes (hydHG) from Salmonella typhimurium; Chopra AK et al.; The nucleotide sequence of the hydHG operon, comprised of chromosomal genes that regulate labile hydrogenase activity in Salmonella typhimurium, was compared with the reported hydHG sequence of Escherichia coli . Nucleotide sequence analysis of a 4.8 kb EcoRI fragment of Salmonella chromosomal DNA revealed that one of the open reading frames (ORF) encoded a protein of 441 amino acid residues . This large ORF was identified on a 2.7 kb Eco RI/HindIII fragment and coded for the complete hydG gene . The carboxy-terminus (626 bp) of the hydH gene also was present immediately upstream of hydG . Expression of the Salmonella hydG gene in a T7 promoter/polymerase system revealed the presence of a unique 45 kDa protein band . The incomplete hydH gene was not expressed . It is proposed that the labile hydrogenase activity in S . typhimurium may be regulated by the multiple component system.

J Bacteriol, 1991 Dec, 173(23), 7511 - 8
Mutations in rpoA affect expression of anaerobically regulated genes in Salmonella typhimurium; Lombardo MJ et al.; oxrB8, a mutation that diminishes the anaerobic induction of pepT and other anaerobically regulated, oxrA (fnr)-dependent Salmonella typhimurium genes, is an allele of rpoA, the gene for the alpha subunit of RNA polymerase . Four additional rpoA mutations that affect anaerobic pepT expression have been isolated after localized mutagenesis of the rpoA region . All but one of these rpoA mutations appear to have relatively specific effects on genes that require the OxrA (FNR) protein, a positive transcriptional regulator of a family of anaerobically expressed genes . All of these mutations lead to amino acid substitutions in the C-terminal region of the alpha subunit . These results taken with a number of previous observations suggest a role for the alpha subunit in the interaction between RNA polymerase and positive transcriptional regulatory proteins . They also suggest that the C-terminal region of alpha is important for these interactions.

J Bacteriol, 1991 Dec, 173(23), 7481 - 90
Multiple mechanisms contribute to osmotic inducibility of proU operon expression in Escherichia coli: demonstration of two osmoresponsive promoters and of a negative regulatory element within the first structural gene; Dattananda CS et al.; Transcription of the proU operon in Escherichia coli is induced several hundredfold upon growth of cells in media of elevated osmolarity . A low-copy-number promoter-cloning plasmid vector, with lacZ as the reporter gene, was used for assaying the osmoresponsive promoter activity of each of various lengths of proU DNA, generated by cloning of discrete restriction fragments and by an exonuclease III-mediated deletion approach . The results indicate that expression of proU in E . coli is directed from two promoters, one (P2) characterized earlier by other workers with the start site of transcription 60 nucleotides upstream of the initiation codon of the first structural gene (proV), and the other (P1) situated 250 nucleotides upstream of proV . Furthermore, a region of DNA within proV was shown to be involved in negative regulation of proU transcription; phage Mu dII1681-generated lac fusions in the early region of proV also exhibited partial derepression of proU regulation, in comparison with fusions further downstream in the operon . Sequences around promoter P1, sequences around P2, and the promoter-downstream negative regulatory element, respectively, conferred approximately 5-, 8-, and 25-fold osmoresponsivity on proU expression . Within the region genetically defined to encode the negative regulatory element, there is a 116-nucleotide stretch that is absolutely conserved between the proU operons of E . coli and Salmonella typhimurium and has the capability of exhibiting alternative secondary structure . Insertion of this region of DNA into each of two different plasmid vectors was associated with a marked reduction in the mean topological linking number in plasmid molecules isolated from cultures grown in high-osmolarity medium . We propose that this region of DNA undergoes reversible transition to an underwound DNA conformation under high-osmolarity growth conditions and that this transition mediates its regulatory effect on proU expression.

J Bacteriol, 1991 Dec, 173(23), 7464 - 70
Characterization of the major promoter for the plasmid-encoded sucrose genes scrY, scrA, and scrB; Cowan PJ et al.; Sucrose genes from a Salmonella thompson plasmid were cloned in Escherichia coli K-12 . A physical map and a genetic map of the genes were constructed, revealing strong homology with the scr regulon from the Salmonella typhimurium plasmid pUR400 . Two promoters were examined after being subcloned into transcriptional fusion vectors . Primer extension analysis and site-directed mutagenesis were used to identify the precise location of the promoter of scrY, scrA, and scrB . Transcription from this promoter was regulated over a 1,000-fold range by the combined effects of ScrR-mediated repression and catabolite repression . A putative cyclic AMP receptor protein binding site centered 72.5 bp upstream of the start point of transcription of scrY appeared to be essential for full activity of the scrY promoter . Transcription from the putative scrK promoter was far less sensitive to repression by ScrR . In ScrR+ cells, readthrough transcription from the putative scrK promoter into scrY accounted for less than 10% of scrY expression.

J Bacteriol, 1991 Dec, 173(23), 7443 - 8
Bacillus subtilis CheN, a homolog of CheA, the central regulator of chemotaxis in Escherichia coli; Fuhrer DK et al.; The Bacillus subtilis cheN gene was isolated, sequenced, and expressed . It encodes a large negatively charged protein with a molecular weight of approximately 74,000 . The predicted protein sequence has 33 to 34% identity with the Escherichia coli and Salmonella typhimurium CheA and Myxococcus xanthus FrzE sequences . These proteins are found to autophosphorylate and are members of the same histidine kinase signal modulating family . CheN has several conserved regions (including the histidine that is phosphorylated in CheA) that coincide with other autophosphorylated signal transducers . A null mutant is defective in attractant-induced methanol formation and shows no behavioral response to chemoeffectors . These results imply that in B . subtilis the mechanism of chemotaxis involves phosphoryl transfer similar to that in E . coli . However, the CheN null mutant mostly tumbles, whereas CheA mutants swim smoothly, and only in B . subtilis does excitation lead to methyl transfer and methanol formation . Thus, the overall mechanism of chemotaxis is different in the two organisms.

Infect Immun, 1991 Dec, 59(12), 4729 - 31
Interleukin-1 administration to C3H/HeJ mice after but not prior to infection increases resistance to Salmonella typhimurium; Morrissey PJ et al.; Interleukin-1 (IL-1) treatment of C3H/HeN and C3H/HeJ mice prior to infection with Salmonella typhimurium increased the survival fraction only in C3H/HeN mice . IL-1 administration after infection resulted in a significant increase in mean survival time in C3H/HeJ but not C3H/HeN mice . Bacterial growth in IL-1-treated C3H/HeJ mice was less than that in control mice.

Infect Immun, 1991 Dec, 59(12), 4391 - 7
Antibody responses in the lungs of mice following oral immunization with Salmonella typhimurium aroA and invasive Escherichia coli strains expressing the filamentous hemagglutinin of Bordetella pertussis; Guzman CA et al.; The filamentous hemagglutinin (FHA) of Bordetella pertussis was expressed in the attenuated aroA mutant of Salmonella typhimurium, SL3261, and in a strain of Escherichia coli harboring Shigella flexneri plasmid pWR110, which encodes bacterial invasiveness for epithelial cells . Expression of FHA in these strains did not interfere with their ability to invade Henle cells . Immunoglobulins A and G specific for FHA were detected in lung washes of mice following oral immunization with the live recombinant organisms; antibody levels were significantly higher than those in mice immunized with killed bacteria administered orally or intraperitoneally . Live oral vaccines carrying protective antigens of B . pertussis may be an important alternative to new-generation component vaccines against whooping cough.

Int J Food Microbiol, 1991 Dec, 14(3-4), 313 - 24
Fate of unirradiated Salmonella in irradiated mechanically deboned chicken meat; Szczawinska ME et al.; Mechanically deboned chicken meat was irradiated at 0, 1.25 and 2.50 kGy (Cesium 137) and inoculated with Salmonella dublin ATCC 15480, Salmonella enteritidis ATCC 9186 or Salmonella typhimurium ATCC 14028 . Samples were then stored at 5 degrees C and 10 degrees C and were subjected to microbiological analysis directly after irradiation and inoculation (time 0), and after 24, 72, 120, 168 and 216 h of storage . Samples stored at 20 degrees C were examined at time 0 and after 6, 12 and 24 h of storage . Irradiation at 1.25 and 2.50 kGy caused an average reduction in bacterial levels of 2.23 and 3.44 logs, respectively . S . dublin, S . enteritidis and S . typhimurium showed very small, insignificant changes in numbers, during storage of meat for 9 days at 5 degrees C . The final populations of S . dublin and S . typhimurium in samples irradiated before inoculation and stored at 10 degrees C or 20 degrees C were greater than the equivalent populations in samples which had not been irradiated before inoculation . Reduction of indigenous microflora in mechanically deboned chicken meat by irradiation may create better conditions for the growth of salmonellae and may thus increase the risk of salmonellosis when accidental contamination and temperature abuse occur after a radiation treatment . Therefore, irradiated mechanically deboned chicken meat should be properly refrigerated and protected against contamination.

Int J Food Microbiol, 1991 Dec, 14(3-4), 261 - 75
An investigation of the effects of four variables on the growth of Salmonella typhimurium using two types of gradient gel plates; Thomas LV et al.; The effect of four variables (pH, temperature, sodium chloride concentration and sodium nitrite concentration) on the growth of Salmonella typhimurium CRA663 was investigated using a two-dimensional gradient gel technique . Two methods were used . In the first method the gradients comprised NaCl and pH and in the second method a temperature gradient incubator was used to produce a temperature-pH gradient . Using image analysis, the growth on the plates was depicted as three-dimensional wire frame graphs . At neutral pH and in conditions of low salt, growth was observed over the temperature gradient range of 14-41 degrees C . The optimum growth range was reduced to 21-29 degrees C in conditions of acid pH and/or increased NaCl concentration . The growth on the temperature-pH gradient plates had an irregular surface appearance suggesting that changes in growth rate were occurring at different points of temperature and pH . The effects of increased salt concentration together with acidic pH increased the inhibitory effect of the sodium nitrite . The gradient gel plate technique may be a means of rapidly screening the effect of multiple variables on the growth on microorganisms that may be found in food.

Poult Sci, 1991 Dec, 70(12), 2433 - 8
Effect of fructooligosaccharide on Salmonella colonization of the chicken intestine; Bailey JS et al.; The influence of fructooligosaccharide (FOS) on the ability of Salmonella typhimurium to grow and colonize the gut of chickens was investigated . In vitro studies showed that Salmonella did not grow when FOS was the sole carbon source . When FOS was fed to chicks at the .375% level, little influence on Salmonella colonization was observed . At the .75% level, 12% fewer FOS-fed birds were colonized with Salmonella compared with control birds . When chicks given a partially protective competitive exclusion (CE) culture were fed diets supplemented with .75% FOS, only 4 of 21 (19%) chickens challenged with 10(9) Salmonella cells on Day 7 became colonized as compared with 14 of 23 (61%) chickens given CE alone . When chickens were stressed by feed and water deprivation on Day 13 and challenged with 10(9) Salmonella on Day 14, 33 of 36 (92%) chickens fed a control diet were colonized compared with only 9 of 36 (25%) chickens fed a .75% FOS diet . Chickens treated with FOS had a fourfold reduction in the level of Salmonella present in the ceca . Feeding FOS in the diet of chickens may lead to a shift in the intestinal gut microflora, and under some circumstances may result in reduced susceptibility to Salmonella colonization.

Microbiol Rev, 1991 Dec, 55(4), 561 - 85
Oxidative stress responses in Escherichia coli and Salmonella typhimurium; Farr SB et al.; Oxidative stress is strongly implicated in a number of diseases, such as rheumatoid arthritis, inflammatory bowel disorders, and atherosclerosis, and its emerging as one of the most important causative agents of mutagenesis, tumorigenesis, and aging . Recent progress on the genetics and molecular biology of the cellular responses to oxidative stress, primarily in Escherichia coli and Salmonella typhimurium, is summarized . Bacteria respond to oxidative stress by invoking two distinct stress responses, the peroxide stimulon and the superoxide stimulon, depending on whether the stress is mediated by peroxides or the superoxide anion . The two stimulons each contain a set of more than 30 genes . The expression of a subset of genes in each stimulon is under the control of a positive regulatory element; these genes constitute the OxyR and SoxRS regulons . The schemes of regulation of the two regulons by their respective regulators are reviewed in detail, and the overlaps of these regulons with other stress responses such as the heat shock and SOS responses are discussed . The products of Oxy-R- and SoxRS-regulated genes, such as catalases and superoxide dismutases, are involved in the prevention of oxidative damage, whereas others, such as endonuclease IV, play a role in the repair of oxidative damage . The potential roles of these and other gene products in the defense against oxidative damage in DNA, proteins, and membranes are discussed in detail . A brief discussion of the similarities and differences between oxidative stress responses in bacteria and eukaryotic organisms concludes this review.

Res Rep Health Eff Inst, 1991 Dec, (46), 1 - 22; discussion 23-33
Role of ring oxidation in the metabolic activation of 1-nitropyrene; Beland FA; Nitrated polycyclic aromatic hydrocarbons are wide-spread environmental pollutants that have been detected in photocopier toners, airborne particulates, coal fly ash, and diesel engine exhaust emissions . 1-Nitropyrene, a representative nitropolycyclic aromatic hydrocarbon present in diesel particulates, is a mutagen in Salmonella typhimurium and a tumorigen in laboratory animals . The activation of 1-nitropyrene to a bacterial mutagen has been attributed to nitroreduction; however, the metabolic pathways involved in its metabolism to a tumorigen are not known, but may involve nitroreduction, ring oxidation, or a combination of the two . In these experiments, we examined the importance of ring oxidation in the activation of 1-nitropyrene (99.85 to 99.98 percent 1-nitropyrene, 0.15 to 0.02 percent 1,3-, 1,6-, and 1,8-dinitropyrene by mass spectral analyses) to a mammalian-cell mutagen and carcinogen . Chinese hamster ovary cells were used to assess the mutagenicity of ring-oxidized 1-nitropyrene metabolites . In the absence of a rat liver 9,000 x g supernatant, 6-hydroxy-1-nitropyrene, 1-nitropyrene-9,10-oxide, and pyrene-4,5-oxide were the most mutagenic compounds tested . 3-Hydroxy-1-nitropyrene, 8-hydroxy-1-nitropyrene, and 1-nitropyrene-4,5-oxide were weaker mutagens, whereas pyrene and 1-nitropyrene were essentially nonmutagenic . The order of mutagenic potency with S9 was: 1-nitropyrene-4,5-oxide greater than 6-hydroxy-1-nitropyrene approximately 1-nitropyrene-9,10-oxide greater than 1-nitropyrene approximately 3-hydroxy-1-nitropyrene approximately 8-hydroxy-1-nitropyrene greater than pyrene approximately pyrene-4,5-oxide, with the last two compounds being nearly nonmutagenic . The epoxide hydrase inhibitor 1,2-epoxy-3,3,3-trichloropropane increased the mutation frequency fivefold . In addition, guinea pig liver microsomes and Aroclor-induced rat liver microsomes, which increased the formation of 1-nitropyrene-4,5-oxide and 1-nitropyrene-9,10-oxide, increased the mutagenic response . Incubation of 1-nitropyrene-4,5-oxide with calf thymus DNA resulted in the formation of three DNA adducts . A similar adduct pattern was observed when Chinese hamster ovary cells were incubated with the oxide . Inclusion of a nitroreductase, xanthine oxidase, in the in vitro incubations resulted in the formation of an additional adduct identified as N-(deoxyguanosin-8-yl)-1-aminopyrene . This adduct was not observed in Chinese hamster ovary cells treated with 1-nitropyrene-4,5-oxide . 1-Nitropyrene-9,10-oxide reacted with calf thymus DNA to give an adduct pattern similar to that observed with 1-nitropyrene-4,5-oxide . The distribution of adducts was not affected by conducting the reactions in the presence of xanthine oxidase.(ABSTRACT TRUNCATED AT 400 WORDS)

J Vet Pharmacol Ther, 1991 Dec, 14(4), 385 - 94
Distribution of oxytetracycline to tissue cages and granuloma pouches in calves and effect of acute inflammation on distribution to tissue cages; Bengtsson B et al.; The effect of acute inflammation on oxytetracycline (OTC) distribution was studied in a tissue cage model in calves . An acute inflammatory reaction was induced in tissue cages by injecting lipopolysaccharide (LPS) from Salmonella typhimurium . The distribution of OTC to tissue cage fluid (TCF) was also compared with distribution to fluid from granuloma pouches (GPF) . Tissue from LPS-injected cages showed histological changes indicating an acute inflammatory reaction . Concentrations of OTC were higher in LPS cages than in controls; at 1, 2, 4 and 10 h the difference was statistically significant (P less than 0.05) . Numerically the overall elimination rate constant (kel) was larger, elimination half-life (t1/2) shorter, peak concentration (Cmax) higher, and time of peak concentration (Tmax) shorter in LPS cages than in controls . The area under the curve (AUC) of OTC was greater and the ratio AUCTCF/AUCserum was higher in LPS cages than in controls . Although statistically significant differences were not found for all the pharmacokinetic parameters, it was concluded that distribution to and elimination from LPS cages were both faster than in controls . Concentration-time profiles of OTC were similar in TCF and GPF in that concentrations were lower and elimination was more prolonged than in serum . Levels were higher in GPF than in TCF up to 3 h after injection; thereafter the relationship was reversed . Distribution to and elimination processes from GPF appeared to be faster than from TCF as numerically kel was higher, t1/2 shorter and Tmax shorter in GPF than in TCF . It was concluded that the granuloma pouch model and the tissue cage model have similarities in distribution and elimination patterns and that differences are most probably due to differences in the ratio of the surface area to the volume.

Food Chem Toxicol, 1991 Dec, 29(12), 839 - 44
Mutagenic activities of tryptophan metabolites before and after nitrite treatment; Hashizume T et al.; The mutagenic activities of 16 kinds of tryptophan metabolites, before and after nitrite treatment, were examined in the Ames test . None of the compounds showed mutagenic activity before nitrite treatment . After nitrite treatment under acidic conditions, 11 compounds showed mutagenic activity towards Salmonella typhimurium TA100 strain in the absence of a metabolic activation system . Tryptophan induced 1000 revertant colonies/mumol, while 5-hydroxyindole, 5-hydroxytryptamine and 3-hydroxykynurenine, all containing a hydroxy group in the molecule, induced 11,000, 5200 and 2700 revertant colonies/mumol, respectively . These results indicate that the introduction by nitrite treatment of a hydroxy group into the indole or benzene ring of tryptophan-related compounds increases their mutagenic activity.

Toxicol Lett, 1991 Dec, 59(1-3), 51 - 8
Benzo{e}pyrene pretreatment of immature, female C57BL/6J mice results in increased bioactivation of aflatoxin B1 in vitro; Ma XF et al.; Hepatic microsomes were prepared from immature C57BL/6J mice 24 h after receiving intraperitoneal injections of either corn oil, benzo{e}pyrene (BeP, 50 mg/kg) or 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD, 4 x 10(-3) mg/kg) . The capacity of these hepatic microsomes to bioactivate aflatoxin B1 (AFB1), 2-aminoanthracene (AA), benzo{a}pyrene (BaP), 3-methylcholanthrene (MC), 7,12-dimethylbenzanthracene (DMBA), BeP and pyrene (PY) was measured using strain TA100 in the Salmonella typhimurium/microsome reversion assay . BeP pretreatment of mice resulted in a 33% increase in mutagenic potency (MP) of AFB1 over the corn oil controls and a 70% increase in MP relative to TCDD-pretreated microsomes . With AA, BaP and DMBA as promutagens, BeP pretreatment reduced MP an average of 24%, while TCDD pretreatment increased MP of these 3 promutagens 263% compared to controls . Since the general effects of BeP and TCDD on murine hepatic cytochrome P-450 (P450)-mediated activities in this study were discordant, it appears that changes in P450 activity by BeP pretreatment are not mediated through the Ah receptor.

Toxicol Lett, 1991 Dec, 59(1-3), 213 - 20
Mutagenicity studies of kojic acid; Wei CI et al.; Kojic acid, a fungal metabolite produced by some species of Aspergillus and Penicillium, was found to induce sister chromatid exchanges and chromosomal aberrations in Chinese hamster ovary cells in the presence or absence of the rat liver S9 mix . Furthermore, this compound was demonstrated to induce mutations in Salmonella typhimurium strains TA98 and TA100 using both plate-incorporation and preincubation methods.

J Med Microbiol, 1991 Dec, 35(6), 349 - 57
Invasion of HEp-2 cells by strains of Salmonella typhimurium of different virulence in relation to gastroenteritis; Douce GR et al.; Experiments to measure the invasiveness of seven strains of Salmonella typhimurium for HEp-2 cells showed that high inocula (100 bacteria/HEp-2 cell), as used by most workers to synchronise events and to increase the number of bacteria which invade, resulted in recovery of significantly less than 1% of the original inoculum after treatment with gentamicin to kill extracellular bacteria . Also, the cell culture medium became acidic, and microscopic examination of Giemsa-stained monolayers immediately following gentamicin treatment revealed high concentrations of bacteria associated with the cells . Moreover, with bacterium-cell interaction beyond 2 h, many HEp-2 cells became rounded, especially with virulent strains W118 and TML . Thus, the biological significance of the quantitative data was uncertain . The fall in pH and the rounding of HEp-2 cells were prevented by the use of a low (1:1) bacterium: cell ratio; but the recovery of bacteria after treatment with gentamicin was still lower than expected by microscopic examination . After treatment of cells with Triton X-100 to release bacteria, many remained bound to residual cell nuclei . Additional treatment with a rubber policeman, and vigorous pipetting to disperse aggregates of bacteria and cell debris, increased the recovery to c . 10% of the initial inoculum after interaction for 2 h, and 30-80% after 4 h, depending on the strain and experimental conditions . The pattern of invasiveness, but not the absolute count, was highly reproducible on different days and in different hands . However, after interaction exceeding 2 h, the distribution of bacteria was uneven, many cells having no associated organisms, others showing microcolonies.(ABSTRACT TRUNCATED AT 250 WORDS)

Epidemiol Infect, 1991 Dec, 107(3), 521 - 5
The epidemiology of Salmonella in calves: the role of markets and vehicles; Wray C et al.; Environmental contamination has been shown to be an important aspect of the epidemiology of salmonellosis in calves . Markets and transport vehicles are important links in the calf marketing chain and these were investigated to determine the level of salmonella contamination . Salmonellas were isolated from 7 of the 14 markets surveyed, with 31 of 838 samples (3.7%) being positive . Nine different salmonella serotypes, of which the commonest was Salmonella typhimurium, were isolated . Four different phage types of S . typhimurium were detected, the commonest being DT204C . Salmonellas were isolated from 22 of the 107 vehicles (20.6%) examined before washing and from 4 of the 62 vehicles (6.5%) examined after cleaning . Twelve different salmonella serotypes were isolated, of which the most frequent was S . typhimurium . The commonest of the six different S . typhimurium phage types was DT204C . These results indicate that improved cleaning and disinfection routines both for vehicles and markets are necessary to control salmonellosis in calves.

Clin Exp Immunol, 1991 Dec, 86(3), 399 - 404
Molecular mimickry between HLA B27 and Yersinia, Salmonella, Shigella and Klebsiella within the same region of HLA alpha 1-helix; Lahesmaa R et al.; Two new examples of amino acid homology between HLA B27 and microbes triggering HLA B27-associated diseases are described . An outer membrane protein YadA (Yersinia adhesin, previously called Yop1) of Yersinia enterocolitica and Y . pseudotuberculosis shares a linear tetrapeptide with HLA B27 . A cationic outer membrane protein OmpH of Salmonella typhimurium shares homology with five amino acids of HLA B27 in a non-linear fashion . The four amino acids of YadA are also notably included in the hexapeptide identical between Klebsiella pneumoniae nitrogenase and HLA B27, and three of them occur in the pentapeptide shared by a Shigella flexneri protein and HLA B27 . Antibodies against synthetic peptides including HLA B27 homologues sequences of YadA and OmpH were observed in one-third of the patients with HLA B27 associated diseases . Antibodies were directed against a flanking sequence next to the amino acid sequences shared by arthritis-triggering microbes and HLA B27 . The area of identity in each example of this molecular mimicry (Yersinia, Salmonella, Shigella and Klebsiella) is located in the same place on the HLA B27 molecule: between amino acids 70 to 78 in the variable region of alpha 1-helix . This area of HLA B27 molecule includes sites predicted to be important for binding processed antigens.

Carcinogenesis, 1991 Dec, 12(12), 2233 - 7
Evaluation of the in vivo genotoxicity of the structural analogues 2,6-diaminotoluene and 2,4-diaminotoluene using the rat micronucleus test and rat liver UDS assay; George E et al.; The two structural isomers 2,4- and 2,6-diaminotoluene (DAT) differ in their carcinogenic properties; the 2,4-isomer is carcinogenic in rats and mice, whereas the 2,6-isomer has been reported to be non-carcinogenic . Both isomers were reported to be mutagenic in Salmonella typhimurium in the presence of S9, which was confirmed in the present study before in vivo assays were commenced . Both isomers were tested in the rat bone marrow micronucleus test and the rat liver UDS test to investigate how well these assays discriminate between the carcinogenic and the non-carcinogenic isomer . In the micronucleus test both isomers gave weakly positive results; however, with the carcinogen 2,4-DAT this weak effect was only detectable at very toxic doses and therefore the biological relevance of this result is questionable . Thus, the micronucleus test did not discriminate correctly between the carcinogen and the non-carcinogen . With the liver UDS test, discrimination was achieved but the positive effect seen for the carcinogenic isomer was weak and dependent on the method of preparation of the dosing suspensions . The results are discussed in relation to the carcinogenicity data on both compounds . It is concluded that although both isomers are potent genotoxins in vitro they exert their genotoxic potential only weakly in vivo and convincing discrimination between the carcinogenic and non-carcinogenic isomer was not demonstrated.

Mutat Res, 1991 Dec, 264(4), 207 - 12
The influence of the nucleotide excision-repair system on mutagenesis in Salmonella typhimurium LT2 after exposure to low doses of monofunctional alkylating agents; Bacun-Druzina V et al.; The role of nucleotide excision repair in the mutagenicity of the monofunctional alkylating agents N-methyl-N'-nitro-N-nitrosoguanidine (MNNG), methyl methanesulfonate (MMS), N-ethyl-N'-nitro-N-nitrosoguanidine (ENNG), and N-ethyl-N-nitrosourea (ENU) in Salmonella typhimurium was examined . The mutagenic potential of the mutagenic agents used increased in the following order: MMS less than ENU less than ENNG less than MNNG . The results obtained confirm the involvement of nucleotide excision repair in the removal of mutagenic lesions from the DNA of S . typhimurium cells exposed to high doses of methylating as well as ethylating agents . At the low doses of all the alkylating agents used, the nucleotide excision repair-proficient strain was mutagenized more efficiently than the uvrB mutant . This phenomenon, a consequence of competition between nucleotide excision-repair enzymes and constitutive O6-methylguanine-DNA methyltransferase, is discussed.

Mutat Res, 1991 Dec, 264(4), 201 - 6
Repair of cytotoxic lesions induced by N-methyl-N'-nitro-N-nitrosoguanidine in Salmonella typhimurium and Escherichia coli; Matic I et al.; The role of nucleotide excision repair and 3-methyladenine DNA glycosylases in removing cytotoxic lesions induced by N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) in Salmonella typhimurium and Escherichia coli cells was examined . Compared to the E . coli wild-type strain, the S . typhimurium wild-type strain was more sensitive to the same dose of MNNG . Nucleotide excision repair in both bacterial species does not contribute significantly to the survival after MNNG treatment, indicating that the observed differences in survival between S . typhimurium and E . coli should be attributed to DNA-repair systems other than nucleotide excision repair . The survival of the E . coli alkA mutant strain is seriously affected by the lack of 3-methyladenine DNA glycosylase II, accentuating the importance of this DNA-repair enzyme in protecting E . coli cells against the lethal effects of methylating agents . Following indications from our experiments, the existence of an alkA gene analogue in S . typhimurium has been questioned . Dot-blot hybridisation, using the E . coli alkA gene as a probe, was performed, and such a nucleotide sequence was not detected on S . typhimurium genomic DNA . The existence of constitutive 3-methyladenine DNA glycosylase, analogous to the E . coli Tag gene product in S . typhimurium cells, suggested by the results is discussed.

Mutat Res, 1991 Dec, 264(4), 193 - 6
Mutagenicity of 2-methylacrolein, 2-ethylacrolein and 2-propylacrolein in Salmonella typhimurium TA100 . A comparative study; Neudecker T et al.; The C2-alkylated acrolein derivatives 2-methylacrolein, 2-ethylacrolein and 2-propylacrolein are mutagenic in Salmonella typhimurium TA100 . They are direct mutagens, their mutagenic potency being inversely proportional to the size of the alkylating substituent in the C2 position . In the presence of S9 mix, the mutagenicity of all these substances is considerably reduced; the reduction in mutagenicity is inversely proportional to the direct mutagenic potential of the substance . As shown for 2-methylacrolein, the reduction in mutagenicity is dependent on the concentration of S9 in the S9 mix and is not significantly influenced by heat inactivation of the S9 mix or by addition of TCPO, an inhibitor of epoxide hydrolase, to the testing system . There are no indications of enzymatic activation by the metabolizing microsomal system.

Mutat Res, 1991 Dec, 261(4), 261 - 5
Mutagenicity of some heterocyclic amines in Salmonella typhimurium with metabolic activation by human red blood cell cytosol; Duverger-van Bogaert M et al.; Purified human red blood cell cytosol was used to activate the heterocyclic amines 2-amino-3-methylimidazo{4,5-f}quinoline (IQ), 2-amino-3,4-dimethylimidazo{4,5-f}quinoline (MeIQ), 3-amino-1,4-dimethyl-5H-pyrido{4,3-b}indole (Trp-P-1) and 3-amino-1-methyl-5H-pyrido{4,3-b}indole (Trp-P-2) into mutagenic intermediate(s) in the Salmonella test . The liquid preincubation method in the presence of strain TA98 was utilized . In order to understand the mechanism involved in this metabolic activation, some modulators were incorporated in the medium . The results suggest that an oxygenated hemoprotein, probably oxyhemoglobin, is involved in the activation into genotoxic intermediate(s).

Mutat Res, 1991 Dec, 251(2), 233 - 9
Antimutagenicity of propionic acid bacteria; Vorobjeva LI et al.; The antimutagenic effect of dialysed cell extracts of 4 strains of propionic acid bacteria was examined against the mutagenicity of sodium azide in the TA1535 tester strain of Salmonella typhimurium using the Ames test . It was noted that dialysates of 2 strains of Propionibacterium shermanii, P . pentosaceum and P . acnes, significantly reduced sodium azide-induced revertants . The dialysate of propionic acid cocci did not show an antimutagenic effect . The inhibitory activity was enhanced if the mutagen and extract were coincubated for 20 min prior to performing the mutagenicity assay . Antimutagenicity of dialysates from P . shermanii VKM-103 against MNNG and 9-aminoacridine was shown in S . typhimurium strains TA1535 and TA97 . The antimutagenic activity was found in the protein fraction of the cell extract of P . shermanii . The proteins of the dialysate of P . shermanii were separated using a Toyopearl gel column into 3 main peaks according to their molecular weights . The antimutagenic activity towards sodium azide was found in the second and the third peaks . We suggest that dialysates of the cells of propionic acid bacteria contain several kinds of antimutagenic substances with different molecular weights.

Mutat Res, 1991 Dec, 251(2), 227 - 32
In vitro effects of L-ascorbic acid (vitamin C) on aryl hydrocarbon hydroxylase activity in hepatic microsomes of mice; Kiyohara C et al.; When aromatic hydrocarbon (Ah)-responsive and -non-responsive strains of mice were pretreated with 3-methylcholanthrene (MC) or 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), vitamin C reduced the microsomal aryl hydrocarbon hydroxylase (AHH) activity . The AHH inhibitors 7,8-benzoflavone (7,8-BF) and 3-methylsulfonyl-3',4,4',5-tetrachlorobiphenyl (3-MSF-3',4,4',5-tetraCB) showed various inhibitory effects depending upon the types of microsomes, whereas vitamin C exhibited inhibition irrespective of the types of microsomes . 7,8-BF and 3-MSF-3',4,4',5-tetraCB as well as vitamin C suppressed the reverse mutation of the Salmonella typhimurium tester strains TA98 and TA100 induced by benzo{a}pyrene.

Mutat Res, 1991 Dec, 253(3), 215 - 22
A microplate version of the SOS/umu-test for rapid detection of genotoxins and genotoxic potentials of environmental samples; Reifferscheid G et al.; The umu-microtest is a miniaturized automated short-term test version proposed for screening of umuC-dependent mutagenic potentials of chemicals relevant to environmental pollution, river water and industrial waste water . The test is based on the SOS/umu-test and has been modified in order to allow extensive testing of environmental samples . Genetically engineered Salmonella typhimurium (TA1535/pSK1002) are incubated on a microplate rotor in a sloping position for 2 h with the test samples, followed by addition of fresh culture medium to reach a 10-fold dilution of the incubation medium . 2 h later, the activity of the beta-galactosidase, which reflects umuC induction, is determined colorimetrically . The incubation of the bacteria in the presence of the test compounds as well as the assessment of beta-galactosidase activity takes place in 96-well microplates, thus enabling simultaneous screening of large numbers of samples . Data of the genotoxic potentials are available within 8 h . Computer-controlled automation is possible by using a laboratory workstation.

Vet Rec, 1991 Nov 23, 129(21), 461 - 2
Epidemiology of Salmonella typhimurium infection in calves: persistence of salmonellae on calf units; McLaren IM et al.; Salmonella typhimurium DT204C infection is the commonest cause of salmonellosis in calves . On five calf rearing farms a distinct strain, as indicated by plasmid profile analysis, was found to have persisted on the premises for periods ranging from four months to two years, the average being 14 months . The persistence of salmonellae in the environment appears to be an important factor in the epidemiology of calf salmonellosis and clearly indicates the inadequacy of many cleaning and disinfection routines.

FEBS Lett, 1991 Nov 18, 293(1-2), 11 - 5
Interactions between the antimicrobial peptide, magainin 2, and Salmonella typhimurium lipopolysaccharides; Rana FR et al.; Using FT-IR spectroscopy, the effects of magainin 2 on the thermotropic behavior of LPS isolated from wild-type (SL3770) and LPS-mutant strains of Salmonella typhimurium are characterized and compared . The mutant strains include Ra (SL3749), polymyxin-sensitive Rb2(s) (SH5014), polymyxin-resistant Rb2(r) (SH5357) and Rc (HN202) LPS chemotypes, whose polysaccharide chains differ in length but possess an identical number of phosphorylation sites . In all cases, magainin 2 causes a concentration-dependent disordering of the LPS fatty acyl chains . Differences in disordering of LPS correlate more closely with the charge on the LPS molecule (determined by high-resolution 31P NMR) rather than with the length of the LPS sugar side chain, contradicting the currently accepted model for the interaction of cationic antibiotics with the Gram-negative cell envelope.

Science, 1991 Nov 15, 254(5034), 1001 - 3
DNA deaminating ability and genotoxicity of nitric oxide and its progenitors; Wink DA et al.; Nitric oxide (NO), a multifaceted bioregulatory agent and an environmental pollutant, can also cause genomic alterations . In vitro, NO deaminated deoxynucleosides, deoxynucleotides, and intact DNA at physiological pH . That similar DNA damage can also occur in vivo was tested by treating Salmonella typhimurium strain TA1535 with three NO-releasing compounds, including nitroglycerin . All proved mutagenic . Observed DNA sequence changes were greater than 99% C----T transitions in the hisG46 (CCC) target codon, consistent with a cytosine-deamination mechanism . Because exposure to endogenously and exogenously produced NO is extensive, this mechanism may contribute to the incidence of deamination-related genetic disease and cancer.

J Biol Chem, 1991 Nov 15, 266(32), 21548 - 57
Mechanism of mutual activation of the tryptophan synthase alpha and beta subunits . Analysis of the reaction specificity and substrate-induced inactivation of active site and tunnel mutants of the beta subunit; Ahmed SA et al.; The origin of reaction and substrate specificity and the control of activity by protein-protein interaction are investigated using the tryptophan synthase alpha 2 beta 2 complex from Salmonella typhimurium . We have compared some spectroscopic and kinetic properties of the wild type beta subunit and five mutant forms of the beta subunit that have altered catalytic properties . These mutant enzymes, which were engineered by site-directed mutagenesis, have single amino acid replacements in either the active site or in the wall of a tunnel that extends from the active site of the alpha subunit to the active site of the beta subunit in the alpha 2 beta 2 complex . We find that the mutant alpha 2 beta 2 complexes have altered reaction and substrate specificity in beta-elimination and beta-replacement reactions with L-serine and with beta-chloro-L-alanine . Moreover, the mutant enzymes, unlike the wild type alpha 2 beta 2 complex, undergo irreversible substrate-induced inactivation . The mechanism of inactivation appears to be analogous to that first demonstrated by Metzler's group for inhibition of two other pyridoxal phosphate enzymes . Alkaline treatment of the inactivated enzyme yields apoenzyme and a previously described pyridoxal phosphate derivative . We demonstrate for the first time that enzymatic activity can be recovered by addition of pyridoxal phosphate following alkaline treatment . We conclude that the wild type and mutant alpha 2 beta 2 complexes differ in the way they process the amino acrylate intermediate . We suggest that the wild type beta subunit undergoes a conformational change upon association with the alpha subunit that alters the reaction specificity and that the mutant beta subunits do not undergo the same conformational change upon subunit association.

J Exp Med, 1991 Nov 1, 174(5), 1073 - 83
The Salmonella typhimurium locus mviA regulates virulence in Itys but not Ityr mice: functional mviA results in avirulence; mutant (nonfunctional) mviA results in virulence; Benjamin WH Jr et al.; The virulent Salmonella typhimurium strain WB600 carries the mviA allele of the gene mouse virulence A . As shown here, the virulent phenotype of WB600 is the result of a nonfunctional mviA gene . As compared to the functional allele mviA+, mviA increases virulence in Itys mice, but not in Ityr mice . A specific BglII site, mviA4185, between osmZ and galU, located at approximately 35 min on the salmonella chromosome, was within mviA . Insertion of an antibiotic cassette in the mviA4185 site of mviA+ or the homologous mviA4093 site of mviA DNA resulted in virulence when either cassette was recombined into the chromosome . When mviA and mviA+ were both expressed in the same strain with one carried in the chromosome and the other on a plasmid, avirulence was dominant . Replacement of the mviA allele of strain WB600 using P22 transductions of linked antibiotic cassettes cloned into the chromosome of virulent S . typhimurium strains (SR-11, TML, SL1344, C5, ATCC14028, W118-2, and WB600) showed that all but WB600 contained the avirulent mviA+ allele . Southern hybridizations provided no evidence for a second mviA allele anywhere in the genome of the six non-WB600 strains.

Res Microbiol, 1991 Nov-Dec, 142(9), 951 - 63
Sequence and evolution of the FruR protein of Salmonella typhimurium: a pleiotropic transcriptional regulatory protein possessing both activator and repressor functions which is homologous to the periplasmic ribose-binding protein; Vartak NB et al.; The repressor of the fructose (fru) operon of Salmonella typhimurium (FruR) has been implicated in the transcriptional regulation of dozens of genes concerned with central metabolic pathways of carbon utilization . We here report the nucleotide sequence of the gene encoding FruR and analyse both its operator-promoter region and its deduced amino acyl sequence . The FruR protein was overexpressed and was shown to have a molecular weight of about 36 kDa in agreement with the molecular weight deduced from the gene sequence . Sequence analyses revealed that FruR is homologous to 9 distinct bacterial DNA-binding proteins, most of which recognize sugar inducers and all of which possess helix-turn-helix motifs within their N-terminal regions and exhibit sequence identity throughout most of their lengths . FruR is also homologous to the periplasmic ribose-binding protein which serves as a constituent of the ribose transport/chemoreception system . The ribose-binding protein is in turn homologous to binding proteins specific for arabinose and galactose . The periplasmic binding proteins, the structures of some of which have been elucidated in three dimensions, lack the N-terminal helix-turn-helix region, but instead possess N-terminal hydrophobic signal sequences which target them to the periplasm . A phylogenetic tree for the more closely related proteins of this superfamily was constructed, and a signature motif was identified which should facilitate future detection of additional transcriptional regulatory proteins belonging to this family.

Biochim Biophys Acta, 1991 Nov 11, 1090(3), 351 - 4
Nucleotide sequence analysis of purH and purD genes from Salmonella typhimurium; Chopra AK et al.; The purH and purD genes coding for the 5'-phosphoribosyl 5-amino-imidazole-4-carboxamide (AICAR) transformylase and 5'-phosphoribosyl-glycinamide (GAR) synthetase, respectively, were identified on a 4.8 kb Eco RI fragment of chromosomal DNA from Salmonella typhimurium . Nucleotide sequence analysis of the cloned fragment revealed the presence of two large open reading frames (O.R.F.), which were separated by 11 base pairs (bp) . Substantial DNA and amino acid sequence homology was noted between the purH and purD genes of S . typhimurium and Escherichia coli . Expression of the Salmonella purD gene in a T7 polymerase/promoter system revealed the presence of a 49 kDa protein band by SDS-PAGE and subsequent autoradiography . The purH gene of Salmonella was not expressed since the 5' end of this gene was not cloned.

J Mol Biol, 1991 Nov 5, 222(1), 67 - 88
Systematic mutation of bacteriophage T4 lysozyme; Rennell D et al.; Amber mutations were introduced into every codon (except the initiating AUG) of the bacteriophage T4 lysozyme gene . The amber alleles were introduced into a bacteriophage P22 hybrid, called P22 e416, in which the normal P22 lysozyme gene is replaced by its T4 homologue, and which consequently depends upon T4 lysozyme for its ability to form a plaque . The resulting amber mutants were tested for plaque formation on amber suppressor strains of Salmonella typhimurium . Experiments with other hybrid phages engineered to produce different amounts of wild-type T4 lysozyme have shown that, to score as deleterious, a mutation must reduce lysozyme activity to less than 3% of that produced by wild-type P22 e416 . Plating the collection of amber mutants covering 163 of the 164 codons of T4 lysozyme, on 13 suppressor strains that each insert a different amino acid substitutions at every position in the protein (except the first) . Of the resulting 2015 single amino acid substitutions in T4 lysozyme, 328 were found to be sufficiently deleterious to inhibit plaque formation . More than half (55%) of the positions in the protein tolerated all substitutions examined . Among (N-terminal) amber fragments, only those of 161 or more residues are active . The effects of many of the deleterious substitutions are interpretable in light of the known structure of T4 lysozyme . Residues in the molecule that are refractory to replacements generally have solvent-inaccessible side-chains; the catalytic Glu11 and Asp20 residues are notable exceptions . Especially sensitive sites include residues involved in buried salt bridges near the catalytic site (Asp10, Arg145 and Arg148) and a few others that may have critical structural roles (Gly30, Trp138 and Tyr161).

Am J Gastroenterol, 1991 Nov, 86(11), 1675 - 8
Splenic abscess: a diagnostic challenge; Debeuckelaere S et al.; Splenic abscess is uncommon and remains a diagnostic challenge . We present two cases . Both patients had predisposing factors that may have led to the splenic abscess . At admission, both patients presented clinical and roentgenographic signs, suggestive but nonspecific for splenic suppuration . Of particular interest was the isolation of Salmonella typhimurium in our first patient . The literature on splenic abscess is reviewed.

Mutat Res, 1991 Nov, 264(3), 147 - 53
Metabolism of 2,4-dinitrotoluene by Salmonella typhimurium strains TA98, TA98NR and TA98/1,8-DNP6, and mutagenicity of the metabolites of 2,4-dinitrotoluene and related compounds to strains TA98 and TA100; Sayama M et al.; The products detected in the incubation of 2,4-dinitrotoluene (2,4-DNT) with Salmonella typhimurium strains TA98 and TA98/1,8-DNP6 were nitrosonitrotoluenes, hydroxylaminonitrotoluenes, aminonitrotoluenes and dimethyl dinitroazoxybenzene . The capacity of TA98NR to reduce 2,4-DNT was much lower than that of TA98 and TA98/1,8-DNP6 . The bacterial products showed no mutagenic activity in the Ames assay using TA98 and TA100 . These results indicate that the lack of mutagenic activity of 2,4-DNT is not due to low reductive metabolism of 2,4-DNT by the bacteria, but to the lack of mutagenic activity of the bacterial reductive products of 2,4-DNT, including dimethyl dinitroazoxybenzene.

Mutat Res, 1991 Nov, 264(3), 139 - 45
Mutagenic activity of 2-chloro-4-nitroaniline and 5-chlorosalicylic acid in Salmonella typhimurium: two possible metabolites of niclosamide; Espinosa-Aguirre JJ et al.; Niclosamide is an anti-helminthic drug susceptible to being metabolized into a bacterial mutagen by the action of enzymes present in the S9 activation mixture . Additional results from genotoxic studies in rodents and humans suggest that the drug is absorbed from the gastrointestinal tract, and mutagenic metabolites are excreted both in the free form and as conjugated glucuronides . As in the case of other secondary amides, phase I metabolism of niclosamide may result in a hydrolytic cleavage of the amide bond, giving rise to 5-chlorosalicylic acid and 2-chloro-4-nitroaniline as the main metabolites . In this study, the mutagenicity of these compounds was tested using the Salmonella typhimurium assay . Bacterial mutagenicity tests with these 2 compounds reveal a non-mutagenic response with 5-chlorosalicylic acid and a mutagenic one with 2-chloro-4-nitroaniline . However, the mutagenic potency observed with this compound is lower than that of niclosamide . The role of nitroreduction in the activation of niclosamide and 2-chloro-4-nitroaniline was also investigated with the help of S . typhimurium strains TA98NR, YG1020, YG1021 and YG1024 . The results show a pattern of response which is qualitatively similar for both compounds and this indicates that its mutagenicity depends on both nitroreduction and transacetylation.

Mutat Res, 1991 Nov, 251(1), 99 - 107
Characteristics of mutagenesis by glyoxal in Salmonella typhimurium: contribution of singlet oxygen; Ueno H et al.; The characteristics of mutagenesis by glyoxal in Salmonella tester strains TA100 and TA104, and particularly a possible role of active oxygen species, were investigated . Glyoxal was converted into a non-mutagenic chemical with glutathione (GSH) by glyoxalase I, and the mutagenic activity was enhanced by the depletion of intracellular GSH . Glyoxal caused the reduction of nitro blue tetrazolium, which was suppressed by the addition of 2,5-diphenylfuran, superoxide dismutase (SOD) and catalase (CAT), scavengers of singlet oxygen (1O2), superoxide radical (O2-) and hydrogen peroxide (H2O2), respectively . However, only the 1O2 scavenger almost completely suppressed the mutagenic activity of glyoxal . Mutagenicity assays using strains pretreated with N,N-diethyldithiocarbamate of a SOD inhibitor and strains with low levels of SOD and CAT indicated that the mutagenesis by glyoxal was independent of intracellular levels of SOD and CAT, though glyoxal itself repressed them . Therefore, all the results suggest that 1O2 formed from glyoxal is related to its mutagenesis, but that neither O2- nor H2O2 is intracellularly predominantly related to it . The action of glyoxal against SOD and CAT, and the formation of glyoxal adducts with amino acids as their components are also discussed.

Mutat Res, 1991 Nov, 251(1), 13 - 20
Mutagenic activity of 6-azido deoxyhexoses and azido alcohols in Salmonella typhimurium and its inhibition by a structure-similar carbon source in the medium; Juricek M et al.; 6-Azido-6-deoxy (AZd) derivatives of D-glucose, D-mannose, D-altrose, D-allose, L-idose, D-galactose, D-galactonic acid and D-galactitol, 3-azido-1,2-propanediol (azidoglycerol), 3,1-diazido-2-propanol (diazidoglycerol) and (at much higher doses) 2-azidoethanol were mutagenic in Salmonella typhimurium strains TA100 and TA1535 . The mutagenic response was similar to that induced by sodium azide, i.e., the azido compounds failed to induce mutations in strain TA98, and mutagenesis was independent of plasmid pKM101, and independent of external activation . The specific mutagenicity (his+ rev/mmole) of AZd-glucose and AZd-galactose was decreased with increasing concentrations of D-glucose or D-galactose in the minimal agar medium and enhanced 100-fold or more when 0.2% citrate rather than 0.2% glucose served as the carbon source in the medium . Similarly, the mutagenic efficiency of azidoglycerol was inhibited by glycerol but not by D-glucose or D-galactose; however, the mutagenicity of sodium azide was not influenced by any of these carbon sources in the medium . The inhibition of the mutagenic action of azido hexoses and azido alcohols by non-azido structural analogs is assumed to reside in competition in transmembrane transport or for the metabolic pathways.

Mutat Res, 1991 Nov, 251(1), 115 - 21
The involvement of reactive oxygen species in the direct-acting mutagenicity of wine; Ariza RR et al.; The Ara forward mutagenicity assay with Salmonella typhimurium detected wine as a strong mutagen in the absence of mammalian microsomal activation and/or glycosidase activities, in agreement with previous findings . The standard amount (50 microliters) of S9 fraction in the preincubation mutagenesis test abolished most of the mutagenic activity of red wine in the Ara assay . The S9 fraction exerted the same inactivating capacity on hydrogen peroxide and coffee, a complex mixture generating H2O2 . Catalase was identified as the putative S9 component responsible for its inactivating capacity . This specific scavenger for H2O2 abolished around 90% of the mutagenicity of red wine . The suppressing effect of catalase was much less noticeable in white and rose wines . Phenolics are proposed to be responsible for the direct-acting mutagenicity of wine through an auto-oxidative process leading to the production of H2O2.

J Bacteriol, 1991 Nov, 173(22), 7257 - 68
Recombination in Escherichia coli and the definition of biological species; Dykhuizen DE et al.; The DNA sequence of part of the gnd (6-phosphogluconate dehydrogenase) gene was determined for eight wild strains of Escherichia coli and for Salmonella typhimurium . Since a region of the trp (tryptophan) operon and the phoA (alkaline phosphatase) gene have been sequenced from the same strains, the gene trees for these three regions were determined and compared . Gene trees are different from species or strain trees in that a gene tree is derived from a particular segment of DNA, whereas a species or strain tree should be derived from many such segments and is the tree that best represents the phylogenetic relationship of the species or strains . If there were no recombination in E . coli, the gene trees for different genes would not be statistically different from the strain tree or from each other . But, if the gene trees are significantly different, there must have been recombination . Methods are proposed that show these gene trees to be statistically different . Since the gene trees are different, we conclude that recombination is important in natural populations of E . coli . Finally, we suggest that gene trees can be used to create an operational means of defining bacterial species by using the biological species definition.

J Bacteriol, 1991 Nov, 173(22), 7196 - 203
Mismatch repair genes of Streptococcus pneumoniae: HexA confers a mutator phenotype in Escherichia coli by negative complementation; Prudhomme M et al.; DNA repair systems able to correct base pair mismatches within newly replicated DNA or within heteroduplex molecules produced during recombination are widespread among living organisms . Evidence that such generalized mismatch repair systems evolved from a common ancestor is particularly strong for two of them, the Hex system of the gram-positive Streptococcus pneumoniae and the Mut system of the gram-negative Escherichia coli and Salmonella typhimurium . The homology existing between HexA and MutS and between HexB and MutL prompted us to investigate the effect of expressing hex genes in E . coli . Complementation of mutS or mutL mutations, which confer a mutator phenotype, was assayed by introducing on a multicopy plasmid the hexA and hexB genes, under the control of an inducible promoter, either individually or together in E . coli strains . No decrease in mutation rate was conferred by either hexA or hexB gene expression . However, a negative complementation effect was observed in wild-type E . coli cells: expression of hexA resulted in a typical Mut- mutator phenotype . hexB gene expression did not increase the mutation rate either individually or in conjunction with hexA . Since expression of hexA did not affect the mutation rate in mutS mutant cells and the hexA-induced mutator effect was recA independent, it is concluded that this effect results from inhibition of the Mut system . We suggest that HexA, like its homolog MutS, binds to mismatches resulting from replication errors, but in doing so it protects them from repair by the Mut system . In agreement with this hypothesis, an increase in mutS gene copy number abolished the hexA-induced mutator phenotype . HexA protein could prevent repair either by being unable to interact with Mut proteins or by producing nonfunctional repair complexes.

J Bacteriol, 1991 Nov, 173(21), 6896 - 902
Salmonella acid shock proteins are required for the adaptive acid tolerance response; Foster JW; Salmonella typhimurium, as well as other enteric bacteria, experiences significant fluctuations in H+ ion concentrations during growth in diverse ecological niches . In fact, some pH conditions which should kill cells rapidly, such as stomach acidity, are nevertheless tolerated . The complete mechanism for this tolerance is unknown . However, I have recently demonstrated that S . typhimurium has the ability to survive extreme low pH (pH 3.0 to 4.0) if first adapted to mild pH (pH 5.5 to 6.0) . This phenomenon has been referred to as the acidification tolerance response (ATR) . The exposure to mild acid is referred to as preshock, and the proteins involved are called preshock ATR proteins . A second type of encounter with acid, called acid shock, involves shifting cells directly from alkaline conditions (pH 7.7) to acid conditions (pH 4.5 or below) . During acid shock, the organism immediately ceases reproduction and dramatically changes the expression of at least 52 proteins . All but four are distinct from the preshock ATR proteins . Surprisingly, acid shock alone did not afford significant protection against strong acid challenge in minimal medium . Furthermore, inhibiting protein synthesis prior to acid shock revealed that the acid shock proteins do not appear to contribute to acid survival in minimal medium even at pH 4.3 . Constitutive cellular pH homeostatic mechanisms seem sufficient to protect cells at this pH . The data suggest that the induction of acid shock and preshock ATR proteins are separate processes requiring separate signals . However, for S . typhimurium to survive extreme acid conditions, it must induce both the preshock and acid shock systems . Preventing the expression of one or the other eliminates acid tolerance . I propose a two-stage process that allows S . typhimurium to phase in acid tolerance as the environmental pH becomes progressively more acidic.

J Bacteriol, 1991 Nov, 173(21), 6760 - 5
Molecular analysis of the Salmonella typhimurium phoN gene, which encodes nonspecific acid phosphatase; Kasahara M et al.; The phoN gene of Salmonella typhimurium encodes nonspecific acid phosphatase (EC 3.1.3.2), which is regulated by a two-component regulatory system consisting of the phoP and phoQ genes . We cloned the phoN region into a plasmid vector by complementation of a phoN mutant strain and determined the nucleotide sequence of the phoN gene and its flanking regions . The phoN gene could encode a 26-kDa protein, which was identified by the maxicell method as the product of phoN . Results of the enzyme assay and Southern hybridization with chromosomal DNA of Escherichia coli K-12 suggests that there is no phoN gene in E . coli . The regulatory pattern of phoN in E . coli and Southern hybridization analysis of the E . coli chromosome with the S . typhimurium phoP gene suggest that E . coli K-12 also harbors the phoP and phoQ genes.

J Immunol, 1991 Nov 1, 147(9), 3161 - 4
The involvement of tumor necrosis factor in immunity to Salmonella infection; Tite JP et al.; The role of TNF in immunity to Salmonella in mice was studied . Antiserum specific for murine TNF was raised and used to neutralize TNF activity in vivo . Injection of this serum into mice infected with the moderately mouse virulent Salmonella typhimurium strain M525 caused exacerbation of disease . Such treatment had no effect on the course of an infection with an attenuated S . typhimurium aroA (strain SL3261) mutant . However, the protection afforded by immunisation with live SL3261 against challenge with the virulent parent strain (SL1344) was abolished by anti-TNF antiserum . Interestingly both early (3 wk) immunity and late (10 wk) immunity was neutralized by such treatment . Inasmuch as early immunity is considered to be nonspecific and macrophage-mediated while late immunity is considered to be serotype-specific and T cell mediated, this suggests that TNF plays a role in protection from Salmonellosis in both cases.

J Gen Microbiol, 1991 Nov, 137 ( Pt 11), 2505 - 15
The aconitase of Escherichia coli: purification of the enzyme and molecular cloning and map location of the gene (acn); Prodromou C et al.; The aconitase of Escherichia coli was purified to homogeneity, albeit in low yield (0.6%) . It was shown to be a monomeric protein of Mr 95,000 or 97,500 by gel filtration and SDS-PAGE analysis, respectively . The N-terminal amino acid sequence resembled that of the Bacillus subtilis enzyme (citB product), but the similarity at the DNA level was insufficient to allow detection of the E . coli acn gene using a 456 bp citB probe . Phages containing the acn gene were isolated from a lambda-E . coli gene bank by immunoscreening with an antiserum raised against purified bacterial enzyme . The acn gene was located at 28 min (1350 kb) in the physical map of the E . coli chromosome by probing Southern blots with a fragment of the gene . Attempts to locate the gene using the same procedure with oligonucleotide probes encoding segments of the N-terminal amino acid sequence were complicated by the lack of probe specificity and an inaccuracy in the physical map of Kohara et al . (Cell 50, 495-508, 1987) . Aconitase specific activity was amplified some 20-200-fold in cultures transformed with pGS447, a derivative of pUC119 containing the acn gene, and an apparent four-fold activation-deactivation of the phagemid-encoded enzyme was observed in late exponential phase . The aconitase antiserum cross-reacted with both the porcine and Salmonella typhimurium (Mr 120,000) enzymes.

Mol Microbiol, 1991 Nov, 5(11), 2815 - 21
Skp is a periplasmic Escherichia coli protein requiring SecA and SecY for export; Thome BM et al.; Skp of Escherichia coli (OmpH of Salmonella typhimurium) is a protein whose precise function has been obscured by its ubiquity in a wide range of subcellular fractions such as those containing DNA, ribosomes, and outer membranes . Combining in vitro and in vivo techniques we show that Skp is synthesized as a larger precursor that is processed upon translocation across the plasma membrane . Translocation is dependent on the H(+)-gradient, ATP, SecA, and SecY . Upon cellular subfractionation (avoiding non-specific electrostatic interactions) Skp partitions with beta-lactamase into the fraction of soluble, periplasmic proteins . In the context of the export factor properties of Skp previously demonstrated in vitro it is conceivable that this protein is involved in the later steps of protein translocation across the plasma membrane and/or sorting to the outer membrane.

Mol Microbiol, 1991 Nov, 5(11), 2777 - 87
The tonB gene of Serratia marcescens: sequence, activity and partial complementation of Escherichia coli tonB mutants; Gaisser S et al.; The TonB protein plays a key role in the energy-coupled transport of iron siderophores, of vitamin B12, and of colicins of the B-group across the outer membrane of Escherichia coli . In order to obtain more data about which of its particular amino acid sequences are necessary for TonB function, we have cloned and sequenced the tonB gene of Serratia marcescens . The nucleotide sequence predicts an amino acid sequence of 247 residues (Mr 27,389), which is unusually proline-rich and contains the tandem sequences (Glu-Pro)5 and (Lys-Pro)5 . In contrast to the TonB proteins of E . coli and Salmonella typhimurium, translation of the S . marcescens TonB protein starts at the first methionine residue of the open reading frame, which is the only amino acid removed during TonB maturation and export . Only the N-terminal sequence is hydrophobic, suggesting its involvement in anchoring the TonB protein to the cytoplasmic membrane . The S . marcescens tonB gene complemented an E . coli tonB mutant with regard to uptake of iron siderophores, and sensitivity to phages T1 and phi 80, and to colicins B and M . However, an E . coli tonB mutant transformed with the S . marcescens tonB gene remained resistant to colicins Ia and Ib, to colicin B derivatives carrying the amino acid replacements Val/Ala and Val/Gly at position 20 in the TonB box, and they exhibited a tenfold lower activity with colicin D . In addition, the S . marcescens TonB protein did not restore T1 sensitivity of an E . coli exbB tolQ double mutant, as has been found for the overexpressed E . coli TonB protein, indicating a lower activity of the S . marcescens TonB protein . Although the S . marcescens TonB protein was less prone to proteolytic degradation, it was stabilized in E . coli by the ExbBD proteins . In E . coli, TonB activity of S . marcescens depended either on the ExbBD or the TolQR activities.

Microb Pathog, 1991 Nov, 11(5), 347 - 56
Interferon gamma (IFN-gamma) production by gut-associated lymphoid tissue and spleen following oral Salmonella typhimurium challenge; Ramarathinam L et al.; Although IFN-gamma has been shown to play an important role in protection against a systemic S . typhimurium challenge, the in vivo and in vitro production of this cytokine following S . typhimurium infection of the gastrointestinal tract has not been investigated . In this study, IFN-gamma production by gut-associated lymphoid tissue and spleen was investigated in mice following oral challenge with S . typhimurium . Cells obtained from the Peyer's patches (PP), mesenteric lymph nodes (MLN) and spleen (Sp) of mice orally challenged with S . typhimurium were assessed for levels of IFN-gamma mRNA after varying times following in vivo infection . RNA obtained from the above tissues was subjected to reverse transcription followed by PCR amplification using primers specific for murine IFN-gamma . Elevated levels of IFN-gamma mRNA were first detected in the PP at 6 h post-challenge . Elevated levels of IFN-gamma mRNA were then detected in the MLN at 24 h and in the spleen at 4 days post-challenge . These in vivo results were in agreement with the ability of these lymphoid tissues to produce IFN-gamma upon in vitro stimulation with killed S . typhimurium . Neutralization of endogenously produced IFN-gamma by administration of mAb to IFN-gamma completely abrogated resistance to an oral challenge of S . typhimurium . A significant difference in the percent mortality was observed between the antibody-treated and control groups . Evaluation of bacterial spread in the antibody treated group versus the control group at 4 days following oral challenge revealed higher numbers of bacteria in the spleen and liver of antibody treated mice . These results clearly show that IFN-gamma is rapidly produced by gut-associated lymphoid tissue and spleen following oral S . typhimurium infection, and that endogenous production of IFN-gamma is essential in host resistance to S . typhimurium.

Nippon Saikingaku Zasshi, 1991 Nov, 46(6), 929 - 31
{Utilization of D-histidine by the derivative strain TA100 of Salmonella typhimurium LT 2}; Ohtsuka M et al.; In general, wild-type gram-negative enteric bacteria are not able to utilize D-amino acids as the precursors of respective L-amino acids . We found, however, that an L-histidine auxotroph mutant, TA100, derived from Salmonella typhimurium strain LT 2 and used in the Ames test, showed a biphasic growth curve in the presence of both L- and D-histidine at concentrations of 5 micrograms/ml and 100 micrograms/ml, respectively . L-histidine may be utilized preferentially and then, after a short lag, D-histidine may be utilized . The short lag time is therefore considered to be the time required for induction of such an enzyme that converts D-histidine to L-histidine and for uptake of D-histidine by the bacterial cells.

Pharmacol Toxicol, 1991 Nov, 69(5), 386 - 9
Genotoxicity of acrylic bone cements; Jensen JS et al.; The genotoxicity of conventional polymethylmethacrylate (PMMA) and a new formulation of bone cement: methylmethacrylate/n-decylmethacrylate/isobornylmethacrylate (MMA/DMA/IBMA) were tested by micronucleus test and reverse mutation assays of Salmonella typhimurium (Ames test) . In extracts from cement pellets (37 degrees, 72 hr) with water and water/ethanol the concentration of MMA was reduced by 13-19 times with the new formulation and the concentrations of accelerators were reduced by 4-5 times . New chemical constituents (DMA, IBMA, dihydroxy-propyl-p-toluidine) were found in negligible concentrations . In the micronucleus test all three cement brands were found non-mutagenic and in the Ames test scattered increased revertant ratios were found without differences between the three brands . The new formulation does not possess any increased risk of genotoxicity.

Mutagenesis, 1991 Nov, 6(6), 537 - 40
Strong influence of the exposure medium on mutagenicity in the Ames test: 7-methylbenz{a}anthracene-5,6-oxide; Glatt H et al.; We have previously shown that the activity of the ionized mutagen, 1-hydroxmethylpyrene sulphate, is strongly enhanced in Salmonella typhimurium TA98, when KCl is present in the exposure medium (50-fold at a concentration of 125 mM KCl) and that the halogen ion is responsible for this effect . Here we show that KCl has the opposite effect on the activity of the lipophilic mutagen, 7-methylbenz{a}anthracene-5,6-oxide, (10-fold decrease at a concentration of 125 mM) and that K+ accounts for this influence . Many other solutes also decreased the mutagenicity of 7-methylbenz{a}anthracene-5,6-oxide, but to a smaller extent than the K+ salts . The stability of 7-methylbenz{a}anthracene-5,6-oxide did not appear to be altered in the presence of KCl (t1/2 approximately 12 min), as determined from mutagenicity experiments in which the test compound was added to the exposure medium at varying times before the bacteria . Furthermore, the influence of the exposure medium was significantly stronger in strain TA98 than in strain TA100 . Taken together these findings argue for an influence of the medium on the bacteria rather than on the test compound . Parallel studies with other mutagens indicate that exposure in distilled water enhances the mutagenicity of many compounds . Exposure in distilled water, in combination with some other modifications, led to a 400-fold increase of the assay sensitivity towards 7-methylbenz{a}anthracene-5,6-oxide, as compared to the usual plate incorporation assay.

Mutagenesis, 1991 Nov, 6(6), 501 - 6
Inhibitory effects of furocoumarins in Salmonella typhimurium TA98 on the mutagenicity of dictamnine and rutacridone, promutagens from Ruta graveolens L; Schimmer O et al.; Eight furocoumarins differing in their basic structure and substitution pattern (angular, linear, dihydrofuran type) were tested for their ability to reduce the mutagenic potency of dictamnine and rutacridone, two alkaloids present in extracts from Ruta graveolens L . Both compounds need metabolic activation by S9 mix in order to exhibit mutagenicity in Salmonella typhimurium strain TA98 . The furocoumarins used in this study did not show any mutagenicity either with or without S9 mix within the dose range tested . However, all the furocoumarins were able to inhibit the mutagenicity induced by dictamnine as well as by rutacridone in a dose-dependent manner . Imperatorin turned out to be the most efficient inhibitor . The inhibitory effect is probably due to the inactivation of the cytochrome P450 enzyme complex which prevents the activation of the promutagens . This is indicative of the desmutagenic character of the furocoumarins . However, there is also some evidence that the reduction of the mutagenicity induced by dictamnine might be caused to a small extent by a mechanism which possibly depends on the competition with furocoumarins for the same sites in the DNA molecule.

East Afr Med J, 1991 Nov, 68(11), 869 - 74
Aerobic and facultative bacterial isolates from blood cultures of children with clinically diagnosed septicaemia; Odhiambo FA et al.; A total of 120 sets of blood cultures were performed aerobically from 60 children with clinically diagnosed septicaemia at Kenyatta National Hospital, Nairobi . Out of these, 36 (30%) sets from 19 (31.7%) patients yielded bacterial growth while 84 (70%) sets from 41 (68.3%) were negative . Salmonella typhimurium was the most frequently isolated bacteria (63%), followed by Staphylococcus aureus (15.8%) . Salmonella typhimurium isolates were mostly multi-antibiotic resistant, most of them only sensitive to amikacin and cefotaxime, while all were resistant to ampicillin and co-trimoxazole, the most frequently used antibiotic in this hospitalPIP: Between March 1987-January 1988, physicians enrolled 60 pediatric patients with a fever who were admitted to the Kenyatta National Hospital in Nairobi, Kenya for various clinical conditions in a study to determine the types, frequency, and antibiotic sensitivity patterns of aerobic and facultative bacterial isolates . Most of the patients were 13 months-4 years old (45%) . 31.7% of the patients had positive blood cultures . Staphylococcus aureus was the 2nd most common bacteria (15.8%) among these patients . Laboratory personnel isolated Salmonella typhimurium in most patients (63%) . In fact, during the same period, the Diagnostic Microbiology Laboratory at the hospital identified Salmonella species in 48% of all isolated bacteria and 35% of these were S . typhimurium . S . typhimurium tended to be present in children with gastroenteritis (41.8%) or a fever of unknown origin (33.3%) . S . typhimurium was very sensitive to amikacin and cefotaxime, but resistant to ampicillin and sulfamethoxazole-trimethoprim . Health workers in Kenya have frequently administered ampicillin and sulfamethoxazole-trimethoprim, but not amikacin and cefotaxime . 67% of the strains of S . typhimurium were resistant to gentamicin and 33% to chloramphenicol . These results along with those of other reports from this hospital indicated a dramatic rise in Gram negative bacteria resistance to antibiotics . Therefore physicians should no longer consider gentamicin as a 1st line antibiotic in treating suspected septicemia patients .

J Gen Microbiol, 1991 Nov, 137 ( Pt 11), 2617 - 25
Regulation of compatible solute accumulation in Salmonella typhimurium: evidence for a glycine betaine efflux system; Koo SP et al.; The regulation of glycine betaine accumulation has been investigated in Salmonella typhimurium . The size of the glycine betaine pool in the cells is determined by the external osmotic pressure and is largely independent of the external glycine betaine concentration . Analysis of the activity of the ProP and ProU transport systems suggests that other systems must be active in the regulation of the glycine betaine pool . Addition of p-chloromercuribenzoate (PCMB) or p-chloromercuribenzene sulphonate (PCMBS) to cells that have accumulated glycine betaine provokes rapid loss of glycine betaine . The route of glycine betaine efflux under the influence of PCMB is independent of either the ProP or ProU transport systems . Rapid loss of the accumulated pool of glycine betaine in the presence of PCMB is specific to glycine betaine and proline; accumulated pools of serine and lysine are not significantly affected by the -SH reagent . A specific glycine betaine/proline efflux system is postulated on the basis of these data and its role in the regulation of glycine betaine and proline accumulation is discussed.

Mol Microbiol, 1991 Nov, 5(11), 2823 - 31
Regulation of toxA and regA by the Escherichia coli fur gene and identification of a Fur homologue in Pseudomonas aeruginosa PA103 and PA01; Prince RW et al.; A multicopy plasmid containing the Escherichia coli fur gene was introduced into Pseudomonas aeruginosa strain PA103C . This strain contains a toxA-lacZ fusion integrated into its chromosome at the toxA locus . Beta-galactosidase synthesis in this strain is regulated by iron, as is seen for exotoxin A production . Beta-galactosidase synthesis and exotoxin A production in PA103C containing multiple copies of E . coli fur was still repressed in low iron conditions . The transcription of regA, a positive regulator of toxA, was also found to be inhibited by multiple copies of the E . coli fur gene . In addition, the ability of PA103C containing multiple copies of E . coli fur to produce protease was greatly reduced relative to PA103C containing a vector control . A polyclonal rabbit serum containing antibodies that recognize E . coli Fur was used to screen whole-cell extracts from Vibrio cholerae, Shigella flexneri, Salmonella typhimurium and Pseudomonas aeruginosa . All strains tested expressed a protein that was specifically recognized by the anti-Fur serum . These results and those described above suggest that Fur structure and function are conserved in a variety of distinct bacterial genera and that at least some of these different genera use this regulatory protein to control genes encoding virulence factors.

Mol Microbiol, 1991 Nov, 5(11), 2753 - 62
Magnesium transport in Salmonella typhimurium: the influence of new mutations conferring Co2+ resistance on the CorA Mg2+ transport system; Gibson MM et al.; The CorA Mg2+ transport system of Salmonella typhimurium mediates both influx and efflux of Mg2+ . Mutations at the corA locus (83.5 min) confer resistance to Co2+ . Using transposon mutagenesis, three additional Co2+ resistance loci (corB, corC, and corD) were found and mapped to 55, 15, and 3min, respectively, on the S . typhimurium chromosome . No mutations corresponding to the reported corB locus at 95 min in Escherichia coli were obtained . The corB, corC, and corD mutations confer levels of Co2+ resistance intermediate between those of the wild-type and corA mutations . Isogenic strains were constructed containing combinations of transposon insertion mutations in each of the three Co(2+)-resistance loci to assess their influence on the CorA Mg2+ transport system . The Vmax and Km values for 28Mg2+ or for 57Co2+ and 63Ni2+ influx, analogues of Mg2+ transported by the CorA system, were changed less than twofold compared with the wild-type values, regardless of the mutation(s) present . However, while efflux of 28Mg2+ through the CorA system was decreased threefold in strains carrying one or two mutant alleles among corB, corC, or corD, efflux was completely abolished in either a corA or a corBCD strain . Thus, although the corA gene product is necessary and sufficient to mediate Mg2+ influx, Mg2+ efflux requires the presence of a wild-type allele of at least one of the corB, corC or corD loci.

Sangyo Igaku, 1991 Nov, 33(6), 463 - 74
{Toxicology of acetonitrile}; Hashimoto K; Acetonitrile is a high-polarity organic solvent widely used in various chemical industries and laboratories . It was once used in consumer goods such as cosmetics . Acetonitrile is readily absorbed through the skin, by inhalation and by ingestion, and acute poisoning and even fatal effects are possible via these routes . The oral LD50 of acetonitrile in mice, which are one of the most susceptible animals to acetonitrile, is 170-520 mg/kg, and LC50 is about 2,700 ppm after one hour of inhalation . The toxic effects of acetonitrile are attributable to the metabolic release of cyanide, but the symptoms of poisoning may be delayed a few hours or more due to slow hepatic metabolism . No information is available yet about the toxicity of intact molecules of acetonitrile or formaldehyde which may be formed together with cyanide in the body . In subacute toxicity experiments in animals, slight changes in hemograms, histopathologic changes in the lung, increase in thyroid function, and other changes have been reported . No information is available about the accumulation of acetonitrile or its metabolites in tissues following repeated administrations, although formaldehyde is known to have high reactivity with macromolecules . No study has yet been done on the chronic toxicity or carcinogenicity of acetonitrile after prolonged administration . Acetonitrile is not mutagenic in the standard test using Salmonella typhimurium . Inhalation of acetonitrile by pregnant animals may produce malformations in the offspring such as axial skeletal disorders at maternally toxic levels . Education and information about the toxicity and regulations on the marketing of acetonitrile are of great importance for the safe use of this material . Further studies and information are needed on the chronic effects of acetonitrile, especially its carcinogenic potency, to human beings.

Food Chem Toxicol, 1991 Nov, 29(11), 765 - 70
Effect of emodin on cooked-food mutagen activation; Lee H et al.; The herbs Rheum palmatum B and Polygonum cuspidatum S are frequently used as laxatives and anticancer drugs in Chinese medicine . The antimutagenic activity of these herbs as well as their active component emodin was examined in Salmonella typhimurium TA98 . The crude extracts and emodin induced a dose-dependent decrease in the mutagenicity of benzo{a}pyrene (B{a}P), 2-amino-3-methylimidazo{4,5-f}quinoline (IQ) and 3-amino-1-methyl-5H-pyrido{4,3-b}indole (Trp-P-2) . Furthermore, emodin reduced the mutagenicity of IQ by direct inhibition of the hepatic microsomal activation and not by interaction with proximate metabolites of IQ and/or by modification of DNA repair processes in the bacterial cell.

Am J Med Sci, 1991 Nov, 302(5), 296 - 7
Case report: salmonellosis complicated by leukocytoclastic vasculitis; Fincher RE et al.; We report the case of a healthy young Hispanic man with Salmonella typhimurium bacteremia and leukocytoclastic vasculitis . Leukocytoclastic vasculitis has not been previously reported as a complication of salmonella gastroenteritis and bacteremia . Salmonella gastroenteritis is rarely associated with bacteremia in healthy young adults.

J Nat Prod, 1991 Nov-Dec, 54(6), 1531 - 42
Biological activity of novel macrocyclic alkaloids (budmunchiamines) from Albizia amara detected on the basis of interaction with DNA; Mar W et al.; Extracts derived from Albizia amara were found to demonstrate activity in a recently developed hplc system designed to detect compounds capable of interacting with DNA . Further investigation led to the procurement of four sets of alkaloid isolates X1-X4 that were found to be macrocyclic pithecolobine alkaloids . All four isolates interacted with calf thymus DNA and were generally cytotoxic with a battery of cultured mammalian cells . As determined with Salmonella typhimurium strain TM677, isolates X1 and X3 were bactericidal, but not mutagenic . Isolate X1 was found to inhibit the catalytic activity of DNA polymerase, RNA polymerase, and HIV-1 reverse transcriptase . With DNA polymerase, the reaction was shown to be inhibited in a manner that was competitive with respect to DNA . In addition, isolate X1 inhibited each of the following: platelet aggregation, human lymphocyte transformation, phorbol-ester-induced chemiluminescence with human granulocytes, and cyclooxygenase activity . Detection of these alkaloids on the basis of their interaction with DNA exemplifies the validity of this approach.

Mutat Res, 1991 Nov, 261(3), 209 - 16
Lack of mutagenicity of ochratoxin A and B, citrinin, patulin and cnestine in Salmonella typhimurium TA102; Wurgler FE et al.; The Aspergillus mycotoxins ochratoxin A and B, citrinin and patulin as well as combinations of ochratoxin A and citrinin did not induce reverse mutations in Salmonella typhimurium strain TA102 . Therefore there is no indication for the induction of oxidative damage or crosslinks . The same is true for cnestine, a compound extracted from the plant Cnestis glabra.

Mutat Res, 1991 Nov, 261(3), 153 - 62
Antimutagenic and antitumorigenic activities of nordihydroguaiaretic acid; Wang ZY et al.; Nordihydroguaiaretic acid (NDGA), which occurs in the resinous exudates of many plants is used as an antioxidant in fats and oils . In this study we show that NDGA inhibited the mutagenicity of methyl methanesulfonate, benzo{a}pyrene (BP), 2-aminofluorene, and aflatoxin B1 in Salmonella typhimurium strain TA100 or TA98 in the absence and presence of rat hepatic microsomal activation system . The addition of NDGA during and after nitrosation of methylurea (MU) resulted in a dose-dependent inhibition of mutagenicity induced by nitrosation products of MU . In a two-stage skin tumorigenesis protocol using 7,12-dimethylbenz{a}anthracene (DMBA) as the initiating agent followed by twice weekly applications of 12-O-tetradecanoylphorbol-13-acetate (TPA) as tumor promoter, pretreatment of animals with NDGA prior to DMBA application, afforded significant protection against skin tumorigenicity in female SENCAR mice . In additional studies, skin application of NDGA also inhibited the binding of topically applied {3H}BP and {3H}DMBA to epidermal DNA . When assessed in the anti-tumor promotion protocol, pretreatment of animals with NDGA before each application of TPA in DMBA-initiated mouse skin, resulted in 72% decrease in the total number of tumors when compared to non-NDGA pretreated animals . The possible mechanism(s) of the antimutagenic and anti-tumorigenic activities may be due to the multiple effects of NDGA as inhibitor of the carcinogen metabolism and DNA-adduct formation, scavenger of carcinogen free radicals, and as inhibitor of TPA-induced ornithine decarboxylase activity.

J Bacteriol, 1991 Nov, 173(22), 7176 - 85
The Salmonella typhimurium virulence plasmid encodes a positive regulator of a plasmid-encoded virulence gene; Caldwell AL et al.; The 90-kb virulence plasmid of Salmonella typhimurium is necessary for invasion beyond the Peyer's patches to the mesenteric lymph nodes and spleens of orally inoculated mice . Two Tn5 insertions located on the left side of a previously identified 14-kb virulence region (P . A . Gulig and R . Curtiss III, Infect . Immun . 58:3262-3271, 1988) and mapping 272 bp from each other exhibited opposite effects on splenic infection of mice after oral inoculation . spvR23::Tn5 decreased splenic infection by 1,000-fold, whereas a spv-14::Tn5 mutant outcompeted wild-type S . typhimurium for splenic infection by 27-fold in mice fed mixtures of mutated and wild-type S . typhimurium . spvR23::Tn5 was complemented by a virulence plasmid subclone with an insert sequence encoding only an 891-bp open reading frame specifying a 33,000-molecular-weight protein . The amino acid sequence of this open reading frame had significant homology to members of the LysR family of positive regulatory proteins; thus, the gene was named spvR (salmonella plasmid virulence) . To examine the possible regulatory effects of spvR on other virulence genes, we constructed a lacZ operon fusion in a downstream virulence gene, spvB . When spvR subcloned behind the lac promoter was provided on a separate plasmid in trans to the spvB-lacZ operon fusion, transcription of spvB increased 15-fold . spv-14::Tn5, which conferred a competitive advantage to S . typhimurium, increased the expression of a spvR-lacZ operon fusion in cis . spvR is therefore a positive regulator of spvB and an essential virulence gene of S . typhimurium . As opposed to having spvR subcloned behind the lac promoter, the wild-type spvR gene present on the virulence plasmid did not function to positively regulate spvB-lacZ in trans when salmonellae were grown to the log phase in L broth, suggesting that this regulatory system is activated in vivo during infection.

J Bacteriol, 1991 Nov, 173(22), 7151 - 63
Cloning, characterization, and DNA sequence of the rfaLK region for lipopolysaccharide synthesis in Salmonella typhimurium LT2; MacLachlan PR et al.; We have cloned and sequenced the rfaL and rfaK genes for lipopolysaccharide synthesis in Salmonella typhimurium LT2 on a 4.28-kb HindIII fragment from the previously described R' factor pKZ3 (S . K . Kadam, A . Rehemtulla, and K . E . Sanderson, J . Bacteriol . 161:277-284, 1985) . rfaL is thought to encode a component of the O-antigen ligase, and rfaK is believed to encode the N-acetylglucosamine transferase . The genes were identified by the loss of complementation of prototype rfaL and rfaK mutations after Tn1000 mutagenesis . Translation of the nucleotide sequence predicted sizes of 45.9 and 43.1 kDa for the rfaL and rfaK gene products, respectively . Hydropathy analysis of the rfaL product suggested that it was an integral membrane protein . A third gene, rfaZ, was found to be an 808-bp open reading frame on the pyrE side of rfaK . Insertions into rfaZ reduced rfaK complementation, suggesting cotranscription in the pyrE-cysE direction . The rfaL gene is transcribed in the opposite direction in a separate operon which may also include rfaC . An incomplete open reading frame with homology to an Escherichia coli gene in the same region, rfaY, was found on the pyrE side of rfaZ . Complementation studies with Tn1000 insertions in rfaL showed that rfaL446 and rfaL447 are allelic . With the cloning of the rfaL and -K genes, the order of genes within the rfa cluster at 79 units on the linkage map was found to be cysE-rfaDFCLKZYJIBG-pyrE.

Biochim Biophys Acta, 1991 Oct 21, 1097(3), 171 - 6
Studies on the mechanism of Salmonella typhimurium enterotoxin-induced diarrhoea; Khurana S et al.; The unidirectional fluxes of Na+ and Cl- were studied in Salmonella typhimurium enterotoxin-treated rats . There was net secretion of Na+ and Cl- in toxin-treated animals, while in control animals there was net absorption of these ions . In the presence of the Ca(2+)-ionophore, there was net secretion of Na+ and Cl- in the control group, while the ionophore enhanced the secretion of these ions in experimental animals . The calcium channel blocker, verapamil, decreased the secretion induced by salmonella toxin, but could not reverse the secretion to absorption . There was no difference in the net absorption of Ca2+ in both the control and experimental animals . There was a significant increase in the intracellular free calcium concentrations in enterocytes isolated from toxin-treated rat intestines as compared to that in enterocytes isolated from control animals . In the presence of PMA (phorbol-12-myristated-13-acetate) there was net secretion of Na+ and Cl- in the control group, while in the experimental group there was no change in the fluxes of these ions . The selective, potent inhibitor of protein kinase C, H-7 (1-(5-isoquinolinylsulphonyl)-2-methylpiperazine) reversed the secretion of Na+ and Cl- in the toxin-treated group to absorption . The addition of indomethacin also inhibited the secretion induced by salmonella toxin, but failed to reverse it to absorption . However, the addition both H-7 and indomethacin to the experimental group had a partial additive effect . These studies demonstrate that the Salmonella enterotoxin-mediated fluid secretion involves protein kinase C and the arachidonic acid metabolites and perhaps does not involve the extracellular calcium pools.

J Mol Biol, 1991 Oct 20, 221(4), 1461 - 74
Role of the disordered terminal regions of flagellin in filament formation and stability; Vonderviszt F et al.; Terminal regions of flagellin from Salmonella typhimurium, residues 1 to 65 and 451 to 494, have no ordered tertiary structure in solution, which makes them very susceptible to proteolytic degradation . Flagellin was subjected to mild controlled proteolytic treatment with highly specific proteases to remove terminal segments from the disordered regions . It is demonstrated here that various fragments can be readily prepared that differ from each other in 1 x 10(3) to 2 x 10(3) Mr segments in their NH2- or COOH-terminal regions . Terminally deleted fragments of flagellin were used to clarify the role of the disordered regions in the self-assembly of flagellin . The polymerization ability of the fragments was tested by inducing filament formation with ammonium sulfate . We found that fragments of flagellin containing large terminal deletions could form straight filaments, although the stability of these filaments required high salt concentrations . Even a fragment lacking the whole mobile COOH-terminal part of flagellin and 36 residues from the NH2-terminal region could form long filaments . The fragments could be also polymerized onto native flagellar seeds, suggesting that the subunit packing of the filaments of fragments is similar to that of the native ones . The fragments could also copolymerize with native flagellin, resulting in various helical forms . Filaments of fragments were found to be straight at both pH 4.0 and pH 12.5, indicating that they might have lost their polymorphic ability . Our results show that the major part of the disordered terminal regions of flagellin is not essential for polymerization, but it does play an important role in stabilization of the filaments and in influencing their polymorphic conformation.

J Biol Chem, 1991 Oct 15, 266(29), 19510 - 8
Purification of the alternative sigma factor, sigma 54, from Salmonella typhimurium and characterization of sigma 54-holoenzyme; Popham D et al.; The alternative sigma factor sigma 54 of enteric bacteria, or its homologue in other purple bacteria, is required for transcription of genes whose products have diverse physiological roles . Previous studies have indicated that sigma 54 confers on core RNA polymerase the ability to recognize a specific class of promoters but not the ability to isomerize from closed to open complexes . Isomerization requires ATP and one member of a family of activator proteins, it being different activator proteins that allow this form of polymerase to respond to different physiological signals . We have developed a strategy for overproducing and purifying sigma 54 from Salmonella typhimurium and have studied several biochemical properties of reconstituted sigma 54-holoenzyme . The initial binding constant KB for the formation of closed complexes between this holoenzyme and the ginA promoter in our transcription buffer is approximately 3 x 10(8) M-1, which was determined from DNaseI protection assays at 37 degrees C . After the formation of open complexes, several properties of sigma 54-holoenzyme appear to be similar to those of sigma 70-holoenzyme . We have determined the complete nucleotide sequence of the gene encoding sigma 54 (ntrA) in Salmonella.

Biochemistry, 1991 Oct 15, 30(41), 9900 - 7
Primary structure of the assimilatory-type sulfite reductase from Desulfovibrio vulgaris (Hildenborough): cloning and nucleotide sequence of the reductase gene; Tan J et al.; The nucleotide sequence encoding the structural gene (651 bp) and flanking regions for the assimilatory-type sulfite reductase from the sulfate-reducing bacterium Desulfovibrio vulgaris (Hildenborough) was determined after cloning a 1.4 kb HindIII/SalI genomic fragment possessing the gene into Bluescript pBS(+)KS . The primary structure of the protein was deduced, and the molecular mass of the apoprotein was estimated as 24 kDa . The amino acid sequence of the polypeptide shows some similarities at putative {Fe4S4} cluster binding sites in comparison with the heme protein subunit of the larger Escherichia coli and Salmonella typhimurium sulfite reductases and spinach nitrite reductase . This is the first reported sequence of a member of a new class of low molecular weight assimilatory sulfite-reducing enzymes recently identified in a number of anaerobic bacteria {Moura, I., Lina, A . R., Moura, J . J . G., Xavier, A . V., Fauque, G., Peck, H . D., & Le Gall, J . (1986) Biochem . Biophys . Res . Commun . 141, 1032-1041}.

FEMS Microbiol Lett, 1991 Oct 15, 67(3), 291 - 7
Isolation and characterization of bacteriophage FC3-10 from Klebsiella spp; Camprubi S et al.; FC3-10 is a Klebsiella spp . specific bacteriophage isolated on a rough mutant (strain KT707, chemotype Rd) of K . pneumoniae C3 . The bacteriophage receptor for this phage was shown to be the low-molecular mass lipopolysaccharide (LPS) fraction (LPS-core oligosaccharides), specifically the heptose content of the LPS inner-core . This is the first phage isolated on Klebsiella, the receptor for which is the LPS-core . This phage was unable to plate on Salmonella typhimurium LPS mutants with chemotypes Rd2 or Re showing incomplete or no heptose content on their LPS-core, respectively . Spontaneous phage-resistant mutants from different Klebsiella strains were deep-rough LPS mutants or encapsulated revertants from unencapsulated mutant strains.

J Biol Chem, 1991 Oct 15, 266(29), 19519 - 27
Sugar transport by the bacterial phosphotransferase system . Structural and thermodynamic domains of enzyme I of Salmonella typhimurium; LiCalsi C et al.; Enzyme I, the first in the sequence of phosphocarrier proteins of the bacterial phosphoenolpyruvate:glycose phosphotransferase system, is a potential critical point for regulating sugar uptake . The thermal stability of Enzyme I was studied by high sensitivity differential scanning calorimetry . At pH 7.5, thermal unfolding of the protein exhibits two peaks with maxima (Tm) at 47.6 and 55.1 degrees C, indicating that the protein comprises two cooperative unfolding structures . Interaction between the two domains is markedly dependent on pH within the range 6.5-8.5 . At pH 7.5, catalytic activity was unaffected by heating through the first transition but was lost by heating through the second . Cleavage of Enzyme I (63.5 kDa) by trypsin, chymotrypsin, or Staphylococcus aureus V8 protease yields a 30-kDa fragment, EI-N, containing the NH2 terminus and the active site, His-189 . Protease and differential scanning calorimetry experiments show that EI-N is the structural domain corresponding to the cooperative region in the intact enzyme that unfolds at the higher Tm . EI-N catalyzes one activity of Enzyme I; it accepts a phosphoryl group from phosphohistidine-containing phosphocarrier protein but cannot be phosphorylated by phospho-Enzyme I or phosphoenolpyruvate . The phosphoryl transfer between EI-N and the histidine-containing phosphocarrier protein is reversible . Portions of the Salmonella typhimurium ptsI DNA sequence are known; the complete sequence is presented here and compared to Escherichia coli ptsI.

Microb Pathog, 1991 Oct, 11(4), 289 - 95
A hemA mutation renders Salmonella typhimurium avirulent in mice, yet capable of eliciting protection against intravenous infection with S . typhimurium; Benjamin WH Jr et al.; The hemA mutation reduces the virulence of Salmonella typhimurium for mice by at least 10(7)-fold, as measured by change in LD50 . The hemA mutation does not appear to affect killing of salmonella in mice . The salmonella with the hemA mutation persist in the spleen and liver for 2 to 3 weeks following intravenous injection . The most likely effect of the hemA mutation is to block, or retard, growth of S . typhimurium in an aerobic in vivo environment . Intravenous vaccination of susceptible ltys mice with hemA salmonella was able to elicit about 4 logs of protection against invasive infection with wild-type S . typhimurium 78 days after vaccination, at a time when the vaccine strain was no longer detectable in the spleen and liver.

Mol Gen Genet, 1991 Oct, 229(3), 421 - 7
Outer membrane permeability of Escherichia coli K12: isolation, cloning and mapping of suppressors of a defined antibiotic-hypersensitive mutant; Qi SY et al.; We have previously described defined mutants of the TraT protein, an outer membrane lipoprotein specified by F-like plasmids, which sensitize Escherichia coli and Salmonella typhimurium to antibiotics that are normally excluded from the cell . In this paper, the isolation, characterization and molecular cloning of suppressors of one such mutant (pDOC40) is reported . The suppressors, which were isolated by selection for vancomycin-resistant revertants, also restored resistance to several hydrophobic antibiotics although there were no detectable changes in lipopolysaccharides (LPS), phospholipids or outer membrane proteins . Three suppressor loci, provisionally designated sip, for suppression of increased permeability, were cloned in cosmids and mapped by a novel approach involving random sequencing of cloned DNA to identify flanking genes with known map positions . Our results indicate that the sipB locus is located in the 11 min region (485-510 kb) whereas sipC and sipD both map to 82 min (3850-3885 kb) . Additionally, the previously sequenced nlpA gene was also mapped to the 82 min region . The cloned suppressor loci were specific for the permeability phenotype caused by the mutant R6-5 TraT protein and had no effect on the permeability phenotype caused by a related TraT mutant of S . typhimurium.

Mutat Res, 1991 Oct, 253(2), 181 - 91
Inhibition of dinitropyrene mutagenicity in vitro and in vivo using Salmonella typhimurium and the intrasanguinous host-mediated assay; Shah AB et al.; Dinitropyrenes (DNP), present in polluted air, are potent direct-acting mutagens in Salmonella typhimurium TA98 . This mutagenicity is markedly reduced in the presence of rat-liver S9 or microsomes . This has now been confirmed using mouse hepatic fractions . Since most in vitro test systems do not adequately simulate conditions encountered in the intact animal, we have investigated dinitropyrene mutagenicity to Salmonella in the host-mediated assay . 1,8-Dinitropyrene (1,8-DNP) given p.o . to BALB/c mice induced a weak mutagenic effect in S . typhimurium TA98 recovered from the liver 1 h after i.v . administration (optimum time) . Over the entire dose range tested no toxicity to bacterial cells was detected . Mutation induction in vivo was dose-related with maximum response at 1 mg DNP/kg body weight . This optimum dose, however, was non-mutagenic to strains TA98/1,8-DNP6 (O-transacetylase-deficient) or TA98NR/1,8-DNP6 (nitroreductase- and O-transacetylase-deficient) . 1,3-Dinitropyrene and 1,6-dinitropyrene were weakly mutagenic to TA98 at doses similar to 1,8-DNP . Studies with {14C}1,8-DNP showed that 1 h after oral dosing (1 mg/kg), over 100 ng of 1,8-DNP equivalents were present in the liver (= 0.73% dose) . However, only about 5.5 ng were present in the bacterial pellet, suggesting that hepatic components in vivo, as in vitro, bind to DNP, thus interfering with its interaction with Salmonella.

Mutat Res, 1991 Oct, 253(2), 149 - 59
Assessing the use of known mutagens to calibrate the Salmonella typhimurium mutagenicity assay: II . With exogenous activation; Claxton LD et al.; In order to determine the usefulness of selected chemicals as potential reference materials for calibrating the Salmonella assay, two laboratories tested a series of Salmonella mutagens that require exogenous activation . When the variance for individual substances within a bioassay is sufficiently low and the rankings of those substances are of acceptable consistency, they can later be evaluated for use as standard control compounds, as audit materials, and as standard reference materials for comparative bioassay efforts . The purpose of this project, therefore, was to evaluate the variability in the mutagenic response of potential reference chemicals that require exogenous metabolic activation in the standard plate-incorporation Salmonella mutagenicity assay, and to develop ranking criteria for mutagenic activity based on these data . Ten indirect-acting mutagens were tested in two laboratories using Salmonella typhimurium TA100 and an Aroclor-induced rat liver S9 . Each laboratory conducted four definitive testing rounds . A different batch of S9 was utilized for every two rounds . Of the 10 chemicals tested only 2-anthramine had a mean slope value greater than 1000 revertants/micrograms . Three chemicals had slope values between 1000 and 100; and five chemicals had slope values between 100 and 10 . The remaining compound, 9,10-dimethyl-1,2-benz{a}anthracene, could not be placed into a single category because it had slope values on either side of 100 revertants per mg . Coefficients of variance were low (i.e., below 25% in most cases) . The low variability achieved in this study may be accounted for by two parameters of the study . First, based on Claxton et al . (1991a) and the S9 optimization for three compounds, the amount of S9 was calibrated to a set amount of protein per plate (1.1 mg/plate) . Secondly, the 10 test doses were placed in the initial, linear, nontoxic portion of the dose-response curves . The use of ten closely spaced, nontoxic doses allowed for a more accurate estimate of the slope.

Mutat Res, 1991 Oct, 253(2), 137 - 47
Assessing the use of known mutagens to calibrate the Salmonella typhimurium mutagenicity assay: I . Without exogenous activation; Claxton LD et al.; There has been an increasing need in genetic toxicology to progress from strictly qualitative tests to more quantitative tests . This, in turn, has increased the need to develop better quality assurance and comparative bioassay methods . In this paper, two laboratories tested 10 Salmonella mutagens in order to determine the usefulness of selected chemicals as potential reference materials to calibrate the Salmonella assay . If variance within a bioassay is sufficiently low and the rankings of the compounds are of acceptable consistency, the chemicals later could be evaluated for use as standard control compounds, as audit materials, and as standard reference materials for comparative bioassay efforts . The results demonstrated that the chosen chemicals (with the possible exception of dimethylcarbamylchloride) provide such consistent results in the Salmonella mutagenicity bioassay that they can be used for semi-quantitative calibration and as possible bioassay controls, special audit chemicals, and potentially as reference standards in comparative bioassay efforts . Reference standards, whether used as audit materials or in comparative bioassays, must be used concurrently with the test substances of interest; used without bias; used in a standardized, highly controlled bioassay; and be tested across an appropriate dose range . The study also shows that when these compounds are used as reference standards much care must be given to the number and spacing of doses if highly reproducible slope values are to be generated . We recommend use of a pilot test to establish a dose range for definitive tests and the placement of doses for the definitive tests within the first half of the linear dose-response curve . For appropriate comparisons, one should replicate the tests using the defined dose range and analyze the results in a non-biased statistical manner.

J Immunol, 1991 Oct 1, 147(7), 2333 - 9
Lipopolysaccharide responsiveness is an important factor in the generation of optimal antigen-specific T cell responses during infection with gram-negative bacteria; Marshall NE et al.; We previously have found that the endotoxin (LPS) of Gram-negative bacteria is a major determinant of macrophage Ia induction during infection with these organisms . Specifically, i.p . injection of Gram-negative bacteria elicits a striking macrophage Ia response in LPS-responder mice but virtually no response in LPS-low-responder mice . As an extension of these findings, in this report we have tested the hypothesis that the inability of LPS-low responder mice to mount an Ia response during Gram-negative infection may in turn impair their capacity for generation of appropriate antibacterial T cell responses . Our results demonstrate that for a variety Gram-negative organisms (Salmonella typhimurium, Salmonella minnesota, and Escherichia coli), both macrophage Ia induction and the generation of Ag-specific T cell responses are controlled by the lps gene . We also have asked whether the expression of additional toxins (other than LPS) by infecting Gram-negative organisms can "override" this lps gene control of macrophage and T cell responses . We have found that infection of LPS-low-responder mice with an E . coli strain that expresses a hemolytic exotoxin (Hly) leads to the induction of macrophage Ia expression as well as the generation of T cell responses to both the Hly molecule and to other E . coli-associated Ag, whereas no responses are generated during infection with a Hly- strain . This result suggests that LPS-low responder mice have no inherent defect in T cell responsiveness to Gram-negative bacterial Ag but rather that these mice fail to receive an LPS-mediated signal required for the induction of Ia expression and subsequent generation of peritoneal T cell immunity . These findings, when taken together with results presented in the accompanying paper, strengthen the argument that bacterial toxin production (and the ability of the host to respond to the toxin) can represent a critical determinant of the induction of macrophage Ia expression and in turn, of Ag-specific T cell responses during bacterial infection.

J Bacteriol, 1991 Oct, 173(20), 6597 - 604
Synthesis of thiamine in Salmonella typhimurium independent of the purF function; Downs DM et al.; In Salmonella typhimurium, the first five steps in purine biosynthesis also serve as the first steps in the biosynthesis of the pyrimidine moiety of thiamine (vitamin B1) . Strains with null mutations of the first gene of purine-thiamine synthesis (purF) can, under some circumstances, grow without thiamine . This suggests the existence of an alternative pathway to thiamine that can function without the purF protein . To demonstrate the nature and map position of the purF mutations corrected, a fine-structure genetic map of the purF gene was made . The map allows identification of deletion mutations that remove virtually all of the purF gene, as defined by mutations . We describe conditions and mutations (panR) which allow B1 synthesis appears to require enzymes which act mutants lacking purF function . The alternative route of B1 synthesis appears to require enzymes which act subsequent to the purF enzyme in the purine pathway.

J Bacteriol, 1991 Oct, 173(19), 6168 - 73
Transcriptional organization of the rfaGBIJ locus of Salmonella typhimurium; Brazas R et al.; The transcriptional organization of the rfaGBIJ gene cluster of Salmonella typhimurium was studied by using lacZ and cat transcriptional probes . The results indicated that the leftward end of the gene cluster (rfaG-rfaB-rfaI) is an operon that is transcribed from one or more promoters that lie upstream of rfaG . The results further indicated that the product of the rfaH (sfrB) gene acts as a positive regulator of transcription of the entire rfaGBIJ cluster . At least one site required for the RfaH-mediated transcriptional regulation lies within or very close to the upstream promoter.

Cancer Res, 1991 Oct 1, 51(19), 5284 - 91
Activation of amino-alpha-carboline, 2-amino-1-methyl-6-phenylimidazo{4,5-b}pyridine and a copper phthalocyanine cellulose extract of cigarette smoke condensate by cytochrome P-450 enzymes in rat and human liver microsomes; Shimada T et al.; The ability of cigarette smoke condensate to induce a genotoxic response has been measured in liver microsomal and reconstituted monooxygenase systems containing rat and human cytochrome P-450 (P-450) enzymes, as determined by umu gene expression in Salmonella typhimurium TA1535/pSK1002 . The reactivities of amino-alpha-carboline and 2-amino-1-methyl-6-phenylimidazo{4,5-b}pyridine (PhIP), two compounds known to be present at considerable levels in cigarette smoke condensate, were also determined and compared with regard to genotoxicity . Amino-alpha-carboline and PhIP are activated principally by P-450 1A2 enzymes in human and rat liver microsomes: (a) activation of both compounds was catalyzed efficiently by liver microsomes prepared from rats treated with 5,6-benzoflavone, isosafrole, or the commercial polychlorinated biphenyl mixture Aroclor 1254, and the activities could be considerably inhibited by antibodies raised against P-450 1A1 or 1A2; (b) the rates of activation of these compounds were correlated with the amount of human P-450 1A2 and of phenacetin O-deethylation activity in different human liver microsomal preparations, and these activities were inhibited by anti-P-450 1A2; (c) reconstituted enzyme systems containing P-450 1A enzymes isolated from rats and humans showed the highest rates of activation of amino-alpha-carboline and PhIP . In rat liver microsomes PhIP may also be activated by P-450 3A enzymes; activity was induced in rats treated with pregnenolone 16 alpha-carbonitrile and was inhibited by anti-human P-450 3A4 . However, in humans the contribution of P-450 3A enzymes could be excluded as judged by the very low effects of anti-P-450 3A4 on the microsomal activities and poor correlation with P-450 3A4-catalyzed activities in various liver samples . Cigarette smoke condensate strongly inhibited the activation of several potent procarcinogens by human liver microsomes, particularly the reactions catalyzed by P-450 1A2, but was not so inhibitory of the activation reactions catalyzed by P-450 3A4 and of P-450 2D6-catalyzed bufuralol 1'-hydroxylation . Genotoxic components of the cigarette smoke condensate were extracted by using copper phthalocyanine cellulose (blue cotton) . Genotoxicity of this extract was observed only after activation by P-450, and the inhibition of P-450 1A2 activities by these extracts was slight.(ABSTRACT TRUNCATED AT 400 WORDS)

Infect Immun, 1991 Oct, 59(10), 3484 - 91
Gamma interferon production in endotoxin-responder and -nonresponder mice during infection; Freudenberg MA et al.; The production of gamma interferon (IFN-gamma) in response to infection and to a number of other agents was compared in Lpsn (C3H/HeN and C57BL/10ScSn) and Lpsd (C3H/HeJ and C57BL/10ScCr) mouse strains . Large differences in IFN-gamma production were observed between C57BL/10ScCr mice and the other mouse strains . With the exception of C57BL/10ScCr, all mouse strains, including C3H/HeJ, exhibited transient levels of IFN-gamma during infection with Salmonella typhimurium . Spleen cells of these mice, explanted on day 3 of infection, produced in vitro IFN-gamma spontaneously; this production was enhanced considerably by heat-killed S . typhimurium, heat-killed Propionibacterium acnes, concanavalin A (ConA), or lipopolysaccharide (LPS) . These stimuli, except for LPS, also induced IFN-gamma production in cultures of normal spleen cells from noninfected animals . In contrast, C57BL/10ScCr mice produced no IFN-gamma following infection with S . typhimurium . Also, spleen cells of these mice, explanted on day 3 of infection, exhibited no spontaneous IFN-gamma production . A marginal response was obtained by additional stimulation of the cells with killed S . typhimurium, and a moderate response was obtained with ConA . Normal spleen cells from noninfected C57BL/10ScCr mice showed no IFN-gamma response to killed S . typhimurium, killed P . acnes, or LPS and only a low response to ConA . Impaired IFN-gamma production in C57BL/10ScCr mice was also evident during infection with Plasmodium chabaudi chabaudi, with which a low IFN-gamma response was seen only occasionally . Also, spleen cells from infected animals (days 2 to 8 after infection) exhibited only a very low level of IFN-gamma production in vitro; however, this production could be enhanced further by ConA . In comparison, C57BL/10ScSn mice infected with P . chabaudi chabaudi produced significant amounts of IFN-gamma . Spleen cells explanted from infected animals produced IFN-gamma spontaneously in vitro; this production was enhanced further by killed P . acnes and ConA . The results showed that in addition to the defect in LPS responsiveness, C57BL/10ScCr mice possess a defect in IFN-gamma production in response to different stimuli . During infection, IFN-gamma production and sensitization to LPS occurred in parallel . Infected Lpsn mice exhibited enhanced sensitivity and infected Lpsd C3H/HeJ mice exhibited reasonable sensitivity to the lethal effects of LPS . Lpsd C57BL/10ScCr mice remained resistant to LPS when infected with S . typhimurium and exhibited only marginal sensitivity when infected with P . chabaudi chabaudi.

Curr Opin Genet Dev, 1991 Oct, 1(3), 319 - 23
Genetic control of the bacterial flagellar regulon; Jones CJ et al.; A number of cis- and trans-acting transcriptional factors in the flagellar regulons of Caulobacter crescentus and Salmonella typhimurium have been identified and characterized to varying degrees over the past year, bringing us closer to understanding the regulations of these complex gene hierarchies.

Avian Dis, 1991 Oct-Dec, 35(4), 809 - 19
Infection and reinfection of chickens with Salmonella typhimurium: bacteriology and immune responses; Hassan JO et al.; Four-day-old chickens infected orally with a spectinomycin-resistant (Spcr) mutant of a highly invasive avian Salmonella typhimurium strain excreted salmonellae in the feces for at least 10 weeks . When these chickens were reinfected at this time with a nalidixic acid-resistant (Nalr) mutant of the same strain, they excreted this mutant in significantly smaller numbers (P less than 0.01) than did a previously uninfected control group . The Nalr mutant had a shorter survival rate in the tissues of the immunized chickens than in tissues of the control birds . The Spcr mutant stimulated strong IgG, IgA, and IgM responses in serum, small-intestinal contents, and bile . These were detected by enzyme-linked immunosorbent assay (ELISA) against antigens of crude whole bacterial cell protein sonicate, lipopolysaccharide, flagella, and outer-membrane proteins . There was some evidence of an anamnestic response with IgA in bile following reinfection with the Salmonella . The peak response of antibody-producing cells from the spleens of infected chickens, assayed by solid-phase ELISA, occurred at 3 weeks postinoculation . A strong delayed hypersensitivity reaction, detected by foot-pad swelling after inoculation with either whole-cell or outer-membrane proteins, was observed between 2 and 5 weeks after infection with the Spcr mutant . The data indicate that outer-membrane proteins are major immunogens for both humoral and cell-mediated arms of the immune system.

Appl Environ Microbiol, 1991 Oct, 57(10), 2956 - 62
Distribution of plasmid- and chromosome-mediated iron uptake systems in Vibrio anguillarum strains of different origins; Conchas RF et al.; We investigated the incidence of plasmid-mediated and chromosome-mediated iron uptake systems in strains of Vibrio anguillarum that belong to serotypes O1 and O2 and were isolated from different fish species and in different geographic areas . All of the strains gave positive reactions in CAS agar medium and in the Arnow test, which indicated that catechol types of siderophores were produced . The majority of V . anguillarum serotype O1 strains harbored a 65-kb plasmid similar to plasmid pJM1 from strain 775, which encodes the siderophore anguibactin and its outer membrane receptor, protein OM2 . All of the isolates harboring this plasmid promoted the growth of an anguibactin-deficient receptor-proficient mutant derived from strain 775, but none of these isolates promoted the growth of mutants lacking receptor OM2 . Furthermore, under iron-limiting conditions all of these strains induced outer membrane proteins that were identical in size to protein OM2 of strain 775 . In contrast, none of the serotype O2 strains contained a high-molecular-weight plasmid, but all of them induced the growth of mutants defective in the anguibactin-mediated system regardless of the presence or absence of receptor OM2 . The serotype O2 strains, but not the plasmid-bearing serotype O1 strains, also induced the growth of Salmonella typhimurium enb-1 which utilizes only enterobactin as a siderophore.(ABSTRACT TRUNCATED AT 250 WORDS)

Indian J Biochem Biophys, 1991 Oct-Dec, 28(5-6), 352 - 7
Circular dichroism studies of the coenzyme environment in the active sites of mutant forms of the beta-subunit in the tryptophan synthase alpha 2 beta 2 complex; Kayastha AM et al.; The circular dichroism has been used to evaluate the effect of mutation on the environment of the pyridoxal phosphate coenzyme in the active site of the beta-subunit in the tryptophan synthase alpha 2 beta 2 complex from Salmonella typhimurium . Seven mutant forms of the alpha 2 beta 2-complex with single amino acid replacements at residues 87, 109, 188, 306, and 350 of the beta-subunit have been prepared by site-directed mutagenesis, purified to homogeneity, and characterized by absorption and circular dichroism spectroscopy . Since the wild type and mutant alpha 2 beta 2 complexes all exhibit positive circular dichroism in the coenzyme absorption band, pyridoxal phosphate must bind asymmetrically in the active site of these enzymes . However, the coenzyme may have an altered orientation or active site environment in five of the mutant enzymes that display less intense ellipticity bands . The mutant enzyme in which lysine 87 is replaced by threonine has very weak ellipticity at 400 nm . Since lysine 87 forms a Schiff base with pyridoxal phosphate in the wild type enzyme, our results demonstrate the importance of the Schiff base linkage for rigid or asymmetric binding . Although the mutant enzymes display spectra in the presence of L-serine that differ from that of the wild type enzyme, addition of alpha-glycerol 3-phosphate converts the spectra of two of the mutant enzymes to that of the wild type enzyme . We conclude that this alpha-subunit ligand may produce a conformational change in the alpha-subunit that is transmitted to the mutant beta-subunits and partially corrects conformational alterations in the mutant enzymes.

Arzneimittelforschung, 1991 Oct, 41(10), 1053 - 7
Mutagenicity studies on catena-(S)-{mu-{N alpha-(3-aminopropionyl)histidinato(2-)-N1,N2,O:N tau}-zinc}; Shibata K et al.; Z-103 (catena-(S)-{mu-{N alpha-(3-aminopropionyl)histidinato (2-)-N1,N2,O:N tau}-zinc}, CAS 107667-60-7) was examined in the bacterial mutation test, a chromosomal aberration test with mammalian cells in culture and the micronucleus test using male mice . 1 . Z-103 did not increase the number of revertants in Escherichia coli WP2 uvrA when tested at up to 5000 micrograms/plate in the presence or absence of metabolic activation . And Z-103 did not increase mutants in Salmonella typhimurium SD 100 (streptomycin dependent strain) or in Salmonella typhimurium TM677 (8-azaguanine sensitive strain) when tested at up to 5000 micrograms/ml in the presence or absence of metabolic activation . 2 . The chromosomal aberration test was carried out with cultured Chinese hamster lung cells (CHL) . For the direct assay procedure, the cells were treated with 3.3 x 10(-4)-3.3 x 10(-6) mol/l Z-103 for 24 or 48 h, after which time chromosome preparations were made . For the metabolic activation assay procedure, the cells were treated with 1.0 x 10(-3)-3.3 x 10(-6) mol/l of Z-103 for 6 h in the presence or absence of metabolic activation, and the chromosome preparations were made after a further 18-h incubation in the absence of Z-103 and metabolic activation . Z-103 did not cause chromosome aberrations either in the presence or in the absence of metabolic activation . 3 . The micronucleus test was performed in ddY male mice . Z-103 was administered orally to mice at a dose of 400, 200 or 100 mg/kg.(ABSTRACT TRUNCATED AT 250 WORDS)

Cell Biol Toxicol, 1991 Oct, 7(4), 371 - 86
In-vitro testing and the carcinogenic potential of several nitrosated indole compounds; Tiedink HG et al.; 4-chloro-methoxyindole is a naturally occurring compound in Vicia faba which can easily react with nitrite to form a N-nitroso compound . In this in vitro study, the potential genotoxic effects of nitrosated 4-chloro-6-methoxyindole and its structural analogue 4-chloroindole were evaluated for the first time by using both Salmonella and Chinese hamster V79 cells . Additionally, the inhibition of gap junctional intercellular communication in V79 cells by these compounds was determined; this is a validated parameter for tumor-promoting activity . Most assays were also performed with nitrosated indole-3-acetonitrile, a naturally occurring compound in brassicas . Both nitrosated chloroindoles were highly mutagenic to Salmonella typhimurium TA100 without the need of exogenous metabolic activation and were potent inducers of Sister Chromatid Exchanges . Nitrosated indole-3-acetonitrile generated the same effects, although at much higher concentrations . Equivocal results were obtained for the nitrosated chloroindoles in a forward mutation assay using the hypoxanthine guaninephosphoribosyltransferase locus . All nitrosated indole compounds significantly inhibited gap junctional intercellular communication . These results indicate that nitrosated chloroindoles and nitrosated indole-3-acetonitrile should be considered as mutagens and agents with potential tumor-promoting capacity.

Acta Chem Scand, 1991 Oct, 45(9), 935 - 44
A strategy for ranking environmentally occurring chemicals . Part VI . QSARs for the mutagenic effects of halogenated aliphatics; Eriksson L et al.; A strategy for the systematic analysis and priority ranking of environmental chemicals has been applied to a class of 58 halogenated aliphatic hydrocarbons . A training set of ten compounds representing this class, was selected by statistical design . The training set compounds were then subjected to biological testing in the Salmonella typhimurium reverse mutation assay (Ames test) . The measured biological data, recorded as dose-response curves, were analyzed to determine the mutagenic potency (slope of the initial portion) and the mutagen dose (MD 50) required to increase the number of revertants above the background by 50% . For each compound, four mutagenic potency estimates and four MD 50 values were determined, all originating from the tester strains TA 100 and TA 1535 with and without metabolic activation . The obtained responses were analyzed with multivariate techniques to give QSAR models relating the mutagenic potency data to the physico-chemical properties of the compounds . Finally, the derived QSARs were used to predict the mutagenic potencies and the MD 50S for the non-tested compounds in the class.

Microbiologica, 1991 Oct, 14(4), 315 - 23
Biological effects of Veillonella parvula and Bacteroides intermedius lipopolysaccharides; Matera G et al.; A comparative study on the endotoxic effects of lipopolysaccharide (LPS) from Veillonella parvula ATCC 10790 and from Bacteroides intermedius BMH was performed using an in vivo approach in the C57BL/6 mouse . Phenol-water extracted LPS of such anaerobes was purified by ultracentrifugation and DNase/RNase digestion, and characterized by a metachromatic assay for endotoxins and by electrophoresis on SDS-polyacrylamide gel and silver staining . Mouse LD50 for V . parvula LPS was 1.479 mg and for B . intermedius greater than 3.160 mg . Sublethal amounts of the LPS from anaerobes as well as from facultative aerobes decreased daily water intake and body weight in the mouse . Endotoxin from Salmonella typhimurium SL1102, Escherichia coli 0128:B12 and V . parvula had a strong effect on water intake and body weight, whereas Bacteroides intermedius LPS activity was very weak . The results of the present report suggest that V . parvula LPS has a toxic in vivo activity on mouse, which is comparable to LPS from classic enteric organisms and stronger than B . intermedius LPS.

Genetics, 1991 Oct, 129(2), 327 - 32
Control of large chromosomal duplications in Escherichia coli by the mismatch repair system; Petit MA et al.; Excessive recombination between repeated, interspersed, and diverged DNA sequences is a potential source of genomic instability . We have investigated the possibility that a mechanism exists to suppress genetic exchange between these quasi-homologous (homeologous) sequences . We examined the role of the general mismatch repair system of Escherichia coli because previous work has shown that the mismatch repair pathway functions as a barrier to interspecies recombination between E . coli and Salmonella typhimurium . The formation of large duplications by homeologous recombination in E . coli was increased some tenfold by mutations in the mutL and mutS genes that encode the mismatch recognition proteins . These findings indicate that the mismatch recognition proteins act to prevent excessive intrachromosomal exchanges . We conclude that mismatch repair proteins serve as general controllers of the fidelity of genetic inheritance, acting to suppress chromosomal rearrangements as well as point mutations.

Infect Immun, 1991 Oct, 59(10), 3787 - 95
Direct expression of Bordetella pertussis filamentous hemagglutinin in Escherichia coli and Salmonella typhimurium aroA; Guzman CA et al.; Nonfused (i.e., nonhybrid) filamentous hemagglutinin (FHA) of Bordetella pertussis was efficiently expressed in Escherichia coli K-12 and Salmonella typhimurium aroA at levels higher than those found in wild-type B . pertussis when the upstream signals of the gene were replaced and the translation initiation region was engineered to optimize translational efficiency . Inclusion of part of the C-terminal FHA open reading frame, whose translation product does not appear to be part of the major secreted species of FHA, was shown to be important in achieving protein expression in both E . coli and S . typhimurium aroA; removal of the downstream gene sequence abolished recombinant FHA production . The levels of expression observed varied widely according to the construct and host bacterium used.

Eur J Immunol, 1991 Oct, 21(10), 2297 - 302
Mycobacterial heat-shock proteins as carrier molecules; Lussow AR et al.; We have previously shown that the priming of mice with live Mycobacterium tuberculosis var . bovis (Bacillus Calmette-Guerin, BCG) and immunization with the repetitive malaria synthetic peptide (NANP)40 conjugated to purified protein derivative (PPD), led to the induction of high and long-lasting titers of anti-peptide IgG antibodies, overcoming the requirement of adjuvants and the genetic restriction of the antibody response to the peptide (Lussow et al., Proc . Natl . Acad . Sci . USA 1990 . 87:2960) . This initial work led us to the following observations . BCG had to be live for priming to lead to the induction of anti-peptide antibodies . Surprisingly, priming with other living microorganisms which chronically infect the macrophage (e.g . Salmonella typhimurium and Leishmania major) also induced anti-peptide antibodies in mice immunized with PPD-(NANP)40 conjugate . It was, thus, hypothesized that molecules expressed during active infection and also known to be highly conserved between species, namely the heat-shock proteins (hsp), could mediate the T cell sensitization required for the production of anti-peptide antibodies . In fact, when the PPD protion of the conjugate was replaced by a highly purified recombinant protein corresponding to the 65-kDa (GroEL-type) hsp of M . bovis, this resulted in the production of anti-(NANP) IgG antibodies in BCG-primed mice, irrespective of the major histocompatibility complex-controlled responsiveness to the (NANP) sequence itself . Further, similar induction of anti-peptide antibody response was also obtained with a recombinant 70-kDa (DnaK-type) hsp of M . tuberculosis, but not with a small molecular mass (18 kDa) of M . leprae . Finally, an adjuvant-free carrier effect for anti-peptide IgG antibody production in BCG-primed mice, was also exerted by the GroEL hsp of Escherichia coli . This finding that hsp can act as carrier molecules without requiring conventional adjuvants is of potential importance in the development of vaccine strategies.

Rev Latinoam Microbiol, 1991 Oct-Dec, 33(4), 239 - 43
Bacteriological and immunological aspects of conventional and germfree mice infected with Salmonella typhimurium; Nardi RM et al.; Bacterial invasiveness and immunological responses were studied in germfree (GF) and conventional (CV) mice infected with Salmonella typhimurium . Bacterial counts of homogenates prepared from liver and spleen showed that the colony forming units (CFU) increased rapidly in GF mice and reached lethal proportions (10(9) cell per organ) by day 6 . In CV mice, these counts increased to about 10(4.5) log cell per organ by day 6 and then declined slowly . An increase in serotype-specific IgM and IgG levels was noted in CV mice with a maximum by day 2 . Very low values of these IgM and IgG were observed in GF mice during the course of infection . Delayed type hypersensitivity (DTH) response as measured by footpad swelling was higher in CV animals . Higher hypersensitivity to LPS during infection in GF animals resulted in death of all the animals tested for DTH after day 2 . The data obtained suggest that during a rapid invasive bacterial infection, the slow development of immune response of GF mice may result in death of these animals.

J Gen Microbiol, 1991 Oct, 137 ( Pt 10), 2307 - 12
Characterization of lip expression in Salmonella typhimurium: analysis of lip::lac operon fusions; Smith RL et al.; Strains of Salmonella typhimurium which have an auxotrophic requirement for lipoic acid were isolated by mutagenesis with the transposable element Mu dJ . The chromosomal location of these insertion mutations was determined to be at 14 map units by bacteriophage P22-mediated cotransduction . The lip gene is transcribed in the clockwise direction relative to the S . typhimurium genetic map . Strains with lip::lac operon fusions were used to characterize the transcriptional activity of the lip promoter . Transcription of the lip gene is not regulated by catabolite repression or lipoic acid concentration . The data indicate that the lip gene product is expressed constitutively at a low level.

Mol Gen Genet, 1991 Oct, 229(3), 428 - 36
Functional complementation between chromosomal and plasmid mutagenic DNA repair genes in bacteria; Sedgwick SG et al.; The umuDC operons of Escherichia coli and Salmonella typhimurium and the analogous plasmid operons mucAB and impCAB have been previously characterized in terms of their roles in DNA repair and induced mutagenesis by radiation and many chemicals . The interrelationships of these mutagenic DNA repair operons were examined in vivo in functional tests of interchangeability of operon subunits in conferring UV resistance and UV mutability phenotypes to wild-type S . typhimurium and umu mutants of E . coli . This approach was combined with DNA and protein sequence comparisons between the four operons and a fifth operon, samAB, from the S . typhimurium LT2 cryptic plasmid . Components of the E . coli and S . typhimurium umu operons were reciprocally interchangeable whereas impCA and mucA could not function with umuC in either of these species . mucA and impB could also combine to give a mutagenic response to UV . These active combinations were associated with higher degrees of conservation of protein sequence than in other heterologous gene combinations and related to specific regions of sequence that may specify subunit interactions . The dominance of the E . coli umuD44 mutation over umuD was revealed in both wild-type E . coli and S . typhimurium and also demonstrated against impCAB . Finally interspecies transfer showed that the apparently poor activity of the S . typhimurium umuD gene in situ is not the result of an inherent defect in umuD but is due to the simultaneous presence of the S . typhimurium umuC sequence . It is suggested that the limitation of umuD activity by umuC in S . typhimurium is the basis of the poor induced mutability of this organism.

J Bacteriol, 1991 Oct, 173(20), 6453 - 9
Molecular characterization of flgM, a gene encoding a negative regulator of flagellin synthesis in Salmonella typhimurium; Gillen KL et al.; The expression of flagellin in Salmonella typhimurium is coupled to the assembly of complete flagella . Mutations which disrupt this coupling define a gene, flgM, which represses the expression of the flagellin genes in strains with mutations in the basal body, switch, or hook flagellar gene (K . L . Gillen and K . T . Hughes, J . Bacteriol . 173:2301-2310, 1991) . Complementation studies demonstrated that the flgM gene is contained within a 600-bp cloned DNA fragment . Sequence analysis revealed that this fragment carries a small open reading frame corresponding to a 97-amino-acid protein . The FlgM protein observed in a T7-mediated expression system showed an apparent molecular mass of 9.5 kDa, similar to the predicted size of 10.6 kDa . Upstream of the flgM coding region is a putative promoter sequence which shows strong homology to that thought to be recognized by the flagellin-specific sigma factor (FliA) . Consistent with the use of this promoter in vivo, promoter mapping by primer extension demonstrated a transcriptional start site 11 bases downstream from the center of the putative -10 promoter element, which was dependent on functional FliA for full expression.

J Immunol, 1991 Sep 15, 147(6), 1954 - 61
Immunosuppression induced by attenuated Salmonella . Reversal by IL-4; al-Ramadi BK et al.; We previously demonstrated that an aroA- strain of Salmonella typhimurium, which provides excellent protection against virulent Salmonella challenge, also rendered immunized mice unable to mount in vivo and in vitro antibody responses to heterologous Ag . Coculture studies using transwell plates indicated that suppression was mediated by soluble factors . The suppressive cells were identified as belonging to the monocytic linkage . Macrophage precursors as well as mature adherent macrophages mediated the observed suppression . In the present study, the mechanism of immunosuppression was investigated . Suppression was found to be genetically nonrestricted as spleen cells from immunized C3HeB/FeJ mice (H-2k) suppressed the anti-SRBC plaque-forming cell (PFC) responses of normal spleen cells from two MHC noncompatible mouse strains, BALB/c (H-2d) and C57BL/6 (H-2b) . Time course experiments demonstrated that the addition of spleen cells from immunized mice to normal splenocytes as late as day 4 of a 5-day assay was still markedly suppressive . Furthermore, suppression of the PFC responses was accompanied by a profound inhibition of the capacity of immune splenocytes to produce IL-2 in response to in vitro stimulation by Con A . Coculture studies showed that immune spleen cells were able to suppress IL-2 production by normal splenocytes in a dose-dependent fashion . However, the suppressed PFC responses of immune spleen cells could not be reversed by the exogenous addition of up to 200 U/ml of IL-2, suggesting that immune splenocytes are also defective in their ability to respond to IL-2 . In marked contrast, suppression of PFC responses was reduced by more than 50% by the addition of as little as 1 U/ml of IL-4 and was completely abrogated when 5 U/ml of IL-4 were added to in vitro cultures of spleen cells from immunized mice . The antisuppressive action of IL-4 appeared to be via its inhibitory effect on activated macrophages . The implications of the above findings are discussed.

Nucleic Acids Res, 1991 Sep 25, 19(18), 4885 - 90
Cloning, sequencing, expression and characterization of DNA photolyase from Salmonella typhimurium; Li YF et al.; We have cloned the phr gene that encodes DNA photolyase from Salmonella typhimurium by in vivo complementation of Escherichia coli phr gene defect . The S.typhimurium phr gene is 1419 base pairs long and the deduced amino acid sequence has 80% identity with that of E . coli photolyase . We expressed the S.typhimurium phr gene in E.coli by ligating the E.coli trc promoter 5' to the gene, and purified the enzyme to near homogeneity . The apparent molecular weight of S.typhimurium photolyase is 54,000 dalton as determined by SDS-polyacrylamide gel electrophoresis, which is consistent with the calculated molecular weight of 53,932 dalton from the deduced phr gene product . S.typhimurium photolyase is purple-blue in color with near UV-visible absorption peaks at 384, 480, 580, and 625 nm and a fluorescence peak at 470 nm . From the characteristic absorption and fluorescence spectra and reconstitution experiments, S.typhimurium photolyase appears to contain flavin and methenyltetrahydrofolate as chromophore-cofactors as do the E.coli and yeast photolyases . Thus, S.typhimurium protein is the third folate class photolyase to be cloned and characterized to date . The binding constant of S.typhimurium photolyase to thymine dimer in DNA is kD = 1.6 x 10(-9) M, and the quantum yield of photorepair at 384 nm is 0.5.

Biochemistry, 1991 Sep 24, 30(38), 9161 - 9
Structural conservation in parallel beta/alpha-barrel enzymes that catalyze three sequential reactions in the pathway of tryptophan biosynthesis; Wilmanns M et al.; Three successive steps in tryptophan biosynthesis are catalyzed by single-domain proteins, each folded as a parallel beta/alpha-barrel, as observed in the crystal structures of the bienzyme (phosphoribosyl)-anthranilate isomerase:indoleglycerolphosphate synthase from Escherichia coli {Priestle, J.P., Grutter, M . G., White, J . L., Vincent, M . G., Kania, M., Wilson, E., Jardetzky, T . S., Kirschner, K., & Jansonius, J . N . (1987) Proc . Natl . Acad . Sci . U.S.A . 84, 5690-5694} and the alpha-subunit of the tetrameric bienzyme tryptophan synthase from Salmonella typhimurium {Hyde, C . C., Ahmed, S . A., Padlan, E . A., Miles, E . W., & Davies, D . R . (1988) J . Biol . Chem . 263, 17857-17871} . Recent refinement of the crystal structures of these enzymes at atomic resolution revealed that they contain a common phosphate group binding site in the beta/alpha-barrel, created by residues of the loop between beta-strand 7 and alpha-helix 7 and the N-terminus of an additional helix 8' . The close similarities of their beta/alpha-barrel structures permitted the alignment of 50-75% of their respective amino acid sequences . Considerable sequence similarity was detected in the regions spanning the phosphate binding sites, whereas the percentage of identical residues was barely significant for the remaining parts of the enzymes . These observations suggest divergent evolution of these three beta/alpha-barrel enzymes involved in tryptophan biosynthesis . The same phosphate binding site was also observed in six other beta/alpha-barrel enzymes that are functionally unrelated to those involved in tryptophan biosynthesis: triosephosphate isomerase, ribulose-1,5-bisphosphate carboxylase/oxygenase, glycolate oxidase, flavocytochrome b2, trimethylamine dehydrogenase, and tentatively also fructosebisphosphate aldolase.(ABSTRACT TRUNCATED AT 250 WORDS)

Ugeskr Laeger, 1991 Sep 23, 153(39), 2747 - 50
{Salmonella infections in patients with systemic lupus erythematosus}; Prieme HB et al.; A retrospective review was undertaken of zoonotic Salmonella infections among 173 patients with systemic lupus erythematosus (SLE) who were followed by two departments of rheumatology in Copenhagen during an average period of 16 years . A total of six Salmonella infections were registered in five patients as one patient had two episodes of infection with Salmonella typhimurium with an interval of three years . All six infections were diagnosed during the years 1986-1990 . During the period 1984 to 1988, the number of registered Salmonella infections increased from 900 to 3,500 in the Danish background population . All six infections were accompanied by Salmonella bacteraemia . the present investigation and studies of the literature demonstrate a considerably increased risk of Salmonella bacteraemia in SLE patients as compared with the population as a whole . This should be borne in mind when febrile SLE patients are investigated.

J Mol Biol, 1991 Sep 5, 221(1), 31 - 4
Crystallization and preliminary X-ray diffraction study of the ligand-binding domain of the bacterial chemotaxis-mediating aspartate receptor of Salmonella typhimurium; Jancarik J et al.; The periplasmic domain of the aspartate chemotaxis receptor from Salmonella typhimurium has been crystallized in the presence and absence of bound aspartate . Both crystal forms were grown by precipitation with lithium sulfate and diffract to 1.8 A resolution . The aspartate receptor structure is believed to be prototypical of a large class of receptors including those for polypeptide growth factor hormones as well as those for small chemotaxis-affector molecules such as aspartate and serine.

Mutat Res, 1991 Sep, 264(1), 7 - 14
Mutagenicity of wood smoke condensates in the Salmonella/microsome assay; Asita AO et al.; Smoke condensates of woods used for food preservation and aromatization in Nigeria were tested for mutagenic activity using Salmonella typhimurium TA98 and TA100 . The woods were: white mangrove (Avicennia nitida), red mangrove (Rhizophora racemosa), mahogany Khaya sp.), abura (Mitragyna ciliata), alstonia (Alstonia boonei) and black afara (Terminalia ivorensis) . Cigarette tar was tested for comparison . The condensates induced dose-dependent increases in the number of His+ revertants mainly with S9 mix . With the exception of mahogany and cigarette smoke condensate, the smoke condensates induced more revertants/microgram condensate in TA100 than in TA98 . The number of revertants/microgram condensate ranged between 0.04 and 0.9 for the wood smoke condensates and was 0.12 for the cigarette smoke in TA100 . The range was between 0.1 and 0.30 for the wood smoke condensates and 0.18 revertants/microgram condensate for cigarette smoke condensate in TA98 . Concentrations of 7 polycyclic aromatic hydrocarbons (PAHs) in the condensates were determined namely, pyrene, benzo{a}pyrene, benz{a}anthracene, benzo{k}fluoranthene, benzo{b}chrysene, benzo{g,h,i}perylene and dibenzo{a,e}pyrene . The condensates contained varying concentrations of the individual PAHs and those with higher concentrations generally showed greater mutagenic activities . However, the order of mutagenic potency in the bacterial strains differed from the order of PAH concentrations, which were lower than the concentrations at which they are reported to induce mutations . When 6 of the PAHs were mixed in the concentrations in which they were found in the individual condensates, the mixtures did not induce mutation so that the contribution of the PAHs to the mutagenic activities of the condensates could not be determined.

J Appl Bacteriol, 1991 Sep, 71(3), 277 - 84
The adsorption of bacteria to immobilized lectins; Patchett RA et al.; The agglutination of a selection of bacteria by some lectins was examined . The lectin from Codium fragile agglutinated seven strains of Salmonella typhimurium . The lectin from Helix pomatia agglutinated eight of 12 strains of Listeria monocytogenes and a further two strains gave a weak agglutination reaction . Helix pomatia lectin conjugated to magnetic microspheres enabled the adsorption of L . monocytogenes from suspension with subsequent elution by the competing ligand N-acetyl galactosamine . Affinity chromatography of a suspension of L . monocytogenes through a column of H . pomatia lectin immobilized on agarose, also adsorbed cells and enabled subsequent elution with N-acetyl galactosamine . The column technique enabled the more rapid adsorption of bacteria perhaps because of improved interactions between bacteria and immobilized lectin.

Vaccine, 1991 Sep, 9(9), 675 - 81
Surface expression of malarial antigens in Salmonella typhimurium: induction of serum antibody response upon oral vaccination of mice; Schorr J et al.; The Escherichia coli OmpA protein can serve as a carrier for the expression of foreign antigens on the surface of gram-negative bacteria . Employing OmpA vectors, immunogenic moieties of the Plasmodium falciparum blood stage antigens SERP and HRPII have been expressed in the attenuated Salmonella typhimurium SR-11 strain . Upon induction, the malaria specific sequences of 189 (HRPII) and 451 (SERP) amino acids, fused into the OmpA protein, have been expressed . By indirect immunofluorescence studies, live bacteria expressing the fusion proteins react anti-SERP and anti-HRPII sera, respectively, indicating that the hybrid OmpA proteins become integrated into the bacterial outer membrane and expose the malarial antigens at the exterior surface . Mice that were immunized orally with S . typhimurium cells expressing HRPII and SERP on their surface show a humoral immune response as determined by the anti-SERP and anti-HRPII IgG and IgM titres . From these experiments it can be concluded that the OmpA surface expression system in combination with established Salmonella vaccine strains can be used to efficiently deliver large antigens to the mucosal immune system.

Mutat Res, 1991 Sep-Oct, 250(1-2), 169 - 74
Mutagen formation on nitrite treatment of indole compounds derived from indole-glucosinolate; Sasagawa C et al.; The mutagenicities of 8 indole compounds (indole-3-acetonitrile, indole-3-carbinol, indole-3-acetamide, indole-3-acetic acid, 3-methylindole, indole-3-aldehyde, indole-3-carboxylic acid and indole) derived from indole glucosinolate were studied by mutation tests on Salmonella typhimurium TA98 and TA100 and Escherichia coli WP2 uvrA/pKM101 with and without S9 mix . None of the 8 indole compounds were mutagenic, but they became mutagenic on these 3 tester strains when treated with nitrite at pH 3 . The nitrite-treated indole compounds were mutagenic without metabolic activation system (S9 mix), and their mutagenicities were decreased by the addition of S9 mix.

Mutat Res, 1991 Sep-Oct, 250(1-2), 161 - 7
Formation of 2-nitro-3-methylimidazo{4,5-f}quinoline, a directly mutagenic product, by near-ultraviolet irradiation of a mixture of 2-amino-3-methylimidazo{4,5-f}quinoline and N-nitrosodimethylamine; Arimoto S et al.; Direct-acting mutagens to Salmonella typhimurium TA98 were found to be formed from heterocyclic amines on exposure to near-ultraviolet light in the presence of N-nitrosodialkylamines . We have isolated the mutagenic photoproduct formed from 2-amino-3-methylimidazo{4,5-f}quinoline (IQ) and N-nitrosodimethylamine, and the product was identified as 3-methyl-2-nitroimidazo{4,5-f}quinoline (IQ(NO2} . The yield of IQ(NO2) from IQ was estimated to be 17% . Similar light-dependent activation of IQ was noted with 4 different nitrosodialkylamines other than nitrosodimethylamine . Furthermore, MeIQ and MeIQx were also activated with nitrosamine and light . These reactions represent an example of interaction between 2 different classes of mutagens.

Mutat Res, 1991 Sep-Oct, 250(1-2), 145 - 52
Comparative direct-acting mutagenicity of 1- and 2-nitropyrene: evidence for 2-nitropyrene mutagenesis by both guanine and adenine adducts; Yu SY et al.; The mutations and DNA adducts produced by the environmental pollutant 2-nitropyrene were examined in Salmonella typhimurium tester strains . 2-Nitropyrene was a stronger mutagen than its extensively studied structural isomer 1-nitropyrene in strains TA96, TA97, TA98, TA100, TA102, TA104 and TA1538 . Both 1- and 2-nitropyrene were essentially inactive in TA1535 . The mutagenicity of 1- and 2-nitropyrene in TA98 was much higher than in TA98NR and the activity of these compounds in TA100 was much higher than in TA100NR . While 1-nitropyrene exhibited similar mutagenicity in strains TA98 and TA98/1,8-DNP6, the mutagenicity of 2-nitropyrene in TA98/1,8-DNP6 was much lower than in TA98 . Analysis of DNA from TA96 and TA104 incubated with 2-nitropyrene indicated the presence of two adducts, N-(deoxyguanosin-8-yl)-2-aminopyrene and N-(deoxyadenosin-8-yl)-2-aminopyrene . The results suggest that 2-nitropyrene is metabolized by bacterial nitroreductase(s) to N-hydroxy-2-aminopyrene, and possibly by activation to a highly mutagenic O-acetoxy ester . DNA adduct formation with deoxyguanosine and deoxyadenosine correlates with the mutagenicity of 2-nitropyrene in tester strains possessing both G:C and A:T mutational targets.

Mol Gen Genet, 1991 Sep, 229(1), 81 - 5
Induction and cleavage of Salmonella typhimurium UmuD protein; Woodgate R et al.; SOS mutagenesis in prokaryotes is dependent upon the inducible activity of the chromosomally encoded UmuDC proteins, or homologous proteins such as MucAB or ImpCAB which are found on naturally occurring plasmids . Relative to Escherichia coli, however, Salmonella typhimurium is much less responsive to the mutagenic effects of DNA-damaging agents, despite the fact that it possesses both chromosomally and plasmid encoded umu-like operons . In E . coli, activation of the UmuD mutagenesis protein to UmuD' via RecA-mediated proteolysis is a critical step in the mutation fixation pathway . We have used a polyclonal antiserum raised against the E . coli UmuD and UmuD' proteins to show that S . typhimurium expresses cross-reacting material only after treatment with the DNA-damaging agent mitomycin C . The S . typhimurium umuDC operon, therefore, appears to be regulated by mechanisms similar to the E . coli umuDC operon . After induction, the S . typhimurium UmuD protein was processed to UmuD' in both S . typhimurium and E . coli . However, the S . typhimurium UmuD protein appears to be cleaved more efficiently than the E . coli UmuD protein under similar conditions . The data suggest that conversion of UmuD to the mutagenically active UmuD' is not the rate-limiting factor accounting for the weakly mutable phenotype of S . typhimurium.

J Bacteriol, 1991 Sep, 173(18), 5876 - 86
The cysP promoter of Salmonella typhimurium: characterization of two binding sites for CysB protein, studies of in vivo transcription initiation, and demonstration of the anti-inducer effects of thiosulfate; Hryniewicz MM et al.; The cysPTWA operons of Escherichia coli and Salmonella typhimurium encode components of periplasmic transport systems for sulfate and thiosulfate and are regulated as part of the cysteine regulons . In vitro transcription initiation from the cysP promoter was shown to require both CysB protein and either O-acetyl-L-serine or N-acetyl-L-serine, which act as inducers, and was inhibited by the anti-inducer sulfide . Thiosulfate was found to be even more potent than sulfide as an anti-inducer . DNase I protection experiments showed two discrete binding sites for CysB protein in the presence of N-acetyl-L-serine . CBS-P1 is located between positions -85 and -41 relative to the major transcription start site, and CBS-P2 is located between positions -19 and +25 . Without N-acetyl-L-serine, the CysB protein protected the region between positions -63 and -11, which was designated CBS-P3 . In gel mobility shift assays, the mobility of CysB protein-cysP promoter complexes was increased by O-acetyl-L-serine, N-Acetyl-L-serine had no effect in gel shift experiments, presumably because its anionic charge results in its rapid removal from the complex during electrophoresis . Comparison of DNA fragments differing with respect to binding site position indicated that complexes with CysB protein contain DNA that is bent somewhere between CBS-P1 and CBS-P2 and that O-acetyl-L-serine decreases DNA bending . Binding studies with fragments containing either CBS-P2 alone, CBS-P1 alone, or the entire cysP promoter region suggest a model in which the complex of bent DNA observed in the absence of O-acetyl-L-serine contains a single CysB protein molecule bound to CBS-P3 . At relatively low CysB protein concentrations, O-acetyl-L-serine would cause a single CysB protein molecule to bind tightly to CBS-P1, rather than to CBS-P3, thereby decreasing DNA bending and increasing complex electrophoretic mobility . At higher CysB protein concentrations, O-acetyl-L-serine would cause a second molecule to bind at CBS-P2, giving a more slowly migrating complex.

Infect Immun, 1991 Sep, 59(9), 2941 - 7
Swine immunity to an attenuated Salmonella typhimurium mutant containing a recombinant plasmid which codes for production of a 31-kilodalton protein of Brucella abortus; Stabel TJ et al.; Salmonella typhimurium chi 4064, an attenuated delta cya delta crp mutant of S . typhimurium SR-11, was shown to be avirulent in swine . S . typhimurium chi 4064 was used as a carrier for plasmid pBA31-R7, which codes for the expression of a 31-kDa protein from Brucella abortus (BCSP31) . Given orally, S . typhimurium chi 4064(pBA31-R7) colonized the intestine and mesenteric lymph nodes of 5- to 6-week-old crossbred swine . Orally immunized animals developed serum and intestinal antibody responses to the B . abortus 31-kDa protein and to salmonella endotoxin as measured by enzyme-linked immunosorbent assay . Similarly immunized swine did not develop delayed-type hypersensitivity following a subcutaneous injection of recombinant BCSP31 . However, swine parenterally immunized with recombinant BCSP31 incorporated in Freund incomplete adjuvant did develop a delayed-type hypersensitivity response to the homologous antigen . The data indicated that oral presentation of antigen to swine in the context of recombinant S . typhimurium effective stimulated mucosal and systemic antibody-mediated immunity but failed to sensitize swine for either an antigen-specific delayed-type hypersensitivity or a blastogenic response to the cloned BCSP31.

Toxicol Lett, 1991 Sep, 58(1), 59 - 67
The effect of extraction solvent on the mutagenicity of airborne particles; Lee H et al.; Two different solvents (acetone and dichloromethane) were compared for their efficacy in extraction of mutagenic compounds from airborne particulate samples . Their mutagenicity was examined with Salmonella typhimurium TA98 in presence or absence of S9 mix . The total mutagenic activity of the acetone extract was 1.8-7.0-fold that of the dichloromethane extract . The content of 1-nitropyrene, 1,6-dinitropyrene, dibenzo{a,h}anthracene and indo{1,2,3-c,d}pyrene in acetone extracts of airborne particulate samples was 3.8-, 3.6-, 6.6- and 1135-fold that of dichloromethane extracts, respectively . 1,8-Dinitropyrene, benzo{a}pyrene, chrysene, benzo{a}fluoranthene, benzo {a} anthracene, and benzo{g,h,i}perylene were found in the acetone extract, but were negative in the dichloromethane extract under the same conditions . However, the amount of pyrene in the dichloromethane extract was much higher than in the acetone extract . These results indicate that the extraction efficacy of 1-nitropyrene, dinitropyrenes and benzo{a}pyrene is higher with acetone than with dichloromethane . This may be the reason why acetone is the most effective solvent in extraction of mutagens from airborne particulate samples.

J Bacteriol, 1991 Sep, 173(18), 5893 - 900
Mutations in trans that affect formate dehydrogenase (fdhF) gene expression in Salmonella typhimurium; Fasciano A et al.; Expression of the fdhF locus of Salmonella typhimurium is shown to be dependent upon ntrA and oxrB . However, the oxrB8 mutation is pleiotropic and also affects the expression of hyd, pepT, and chlC, whereas a mutation in ntrA does not . Insertional inactivation with Tn10 and localized mutagenesis permitted the definition and partial characterization of two new genes, fdhS and fdhR, which appear to be involved in the positive regulation of fdhF expression . Both genes were mapped to the 71- to 72-min region of the S . typhimurium chromosome with the gene order fdhS-crp-fdhR-rpsL . Mutations in fdhS specifically affect fdhF expression without affecting the expression of the other anaerobically induced genes or enzymes that were tested, including hyd, pepT, chlC, nitrite reductase, sulfite reductase, and trimethylamine-N-oxide reductase . Both fdhR and fdhS may be involved in fdhF regulation vis-a-vis oxygen, since localized mutagenesis produced alleles of both genes that permitted the aerobic expression of fdhF . However, fdhR may more directly interact with fdhF, since insertional inactivation of fdhS does not abolish aerobic expression of fdhF in fdhR mutant strains . Taken together, these results suggest that fdhS and fdhR act in concert under anaerobic conditions to activate fdhF transcription.

Mutat Res, 1991 Sep, 264(1), 1 - 5
Plasmid pSK1002-mediated mutator effect and SOS response and SOS mutagenesis of 2,5-dichloronitrobenzol in Salmonella typhimurium; Jin ZC et al.; The plasmid pSK1002 (umuC'-'lacZ) could increase the number of revertants induced by methyl methanesulfonate (MMS) and 4-nitroquinoline-N-oxide (4NQO) in Salmonella typhimurium TA 1535 (his-) . The values induced by N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) were not different irrespective of the presence or absence of plasmid . However, the plasmid pKM101-mediated mutagenesis-enhancing effect was much greater than that mediated by pSK1002 as induced by the 3 mutagens mentioned above . Moreover, the plasmid pSK1002 could induced umu-mediated SOS response in the presence of any of these 3 mutagens or of mitomycin C, and a dose-response relationship was evident . It shows that pSK1002 (umuC'-'lacZ) has a dual biological effect, namely a mutator effect and the effect of inducing the SOS response . Besides, this study has proved SOS mutagenesis of 2,5-dichloronitrobenzol (2,5-DCNB) because of the dual indicator nature of pSK1002 . Therefore, it is probable that pSK1002 could be further developed and applied in studying the relation between the SOS response and mutagenesis and in identifying environmental SOS mutagens.

Infect Immun, 1991 Sep, 59(9), 2901 - 8
Distribution of the invA, -B, -C, and -D genes of Salmonella typhimurium among other Salmonella serovars: invA mutants of Salmonella typhi are deficient for entry into mammalian cells; Galan JE et al.; Invasion of intestinal epithelial cells is an essential virulence factor of salmonellae . A group of genes, invABC and invD, that allow Salmonella typhimurium to penetrate cultured epithelial cells have previously been characterized (J . E . Galan and R . Curtiss III, Proc . Natl . Acad . Sci . USA 86:6383-6387, 1989) . The distribution of these genes among Salmonella isolates belonging to 37 different species or serovars was investigated by Southern and colony blot hybridization analyses . Regions of high sequence similarity to the invABC genes were present in all Salonella isolates examined, while regions of sequence similarity to the invD gene were present in all but one (S . arizonae) of the isolates tested, with little restriction fragment length polymorphism . Sequences similar to these genes were not detected in strains of Escherichia coli, Yersinia spp., or Shigella spp . invA mutants (unable to express the invABC genes) of several Salmonella species or serovars, including S . typhi, were constructed and examined for their ability to penetrate Henle-407 cells . All mutants were deficient for entry into cultured epithelial cells, indicating that the invABC genes were not only present in these strains but also functional.

Eur J Clin Microbiol Infect Dis, 1991 Sep, 10(9), 747 - 9
Presence of quinolone resistance in a strain of Salmonella typhimurium; Hof H et al.; A human isolate of Salmonella typhimurium was found to be highly resistant to several antibiotics including quinolones (MIC of ciprofloxacin 16 mg/l) . Killing by ciprofloxacin was only achieved after prolonged exposure to drug concentrations above the MIC . The quinolone resistance of this particular strain was not mediated by plasmids which, however, coded for several other resistance properties.

Arzneimittelforschung, 1991 Sep, 41(9), 901 - 4
Enhancement of the mutagenicity of anticancer drugs by the calcium antagonists verapamil and fendiline; Scheid W et al.; The enhancement of the mutagenicity of anticancer drugs by the calcium antagonists verapamil (CAS 52-53-9) and fendiline (CAS 13042-18-7) is reviewed . Both calcium antagonists enhance synergistically the induction of chromosome aberrations (dicentric and ring chromosomes) in cultured human lymphocytes by the antitumor agent bleomycin . Since two other calcium antagonists, nifedipine and diltiazem, when tested with the same system, did not show this effect, the comutagenicity of verapamil and fendiline does not seem to be related with calcium antagonism per se . Verapamil furthermore potentiates the induction of various chromosome and chromatid aberrations in Chinese hamster ovary (CHO) cells in vitro by the antitumor agent mitomycin C . In bacteria (Salmonella typhimurium) verapamil enhances synergistically the induction of gene mutations (frameshifts) by several anticancer drugs, including various anilinoacridine derivatives . When applied alone, neither verapamil which was tested in each of the three studies (human lymphocytes, CHO-cells, and bacteria) nor fendiline, which was tested only in human lymphocytes, proved to be mutagenic . To explain the comutagenicity of verapamil and fendiline, it is assumed that they prevent the mutagen (e.g., bleomycin) to be extruded from the cell . Consequently, the mutagen would be accumulated intracellularly and this would enhance its efficiency.

J Ethnopharmacol, 1991 Sep, 34(2-3), 275 - 8
Studies on the antimicrobial activity of Nigella sativa seed (black cumin); Hanafy MS et al.; Filter paper discs impregnated with the diethyl ether extract of Nigella sativa seeds (25-400 micrograms extract/disc) caused concentration-dependent inhibition of Gram-positive bacteria represented by Staphylococcus aureus . Gram-negative bacteria represented by Pseudomonas aeruginosa and Escherichia coli (but not Salmonella typhimurium) and a pathogenic yeast Candida albicans . The extract showed antibacterial synergism with streptomycin and gentamicin and showed additive antibacterial action with spectinomycin, erythromycin, tobramycin, doxycycline, chloramphenicol, nalidixic acid, ampicillin, lincomycin and sulphamethoxyzole-trimethoprim combination . The extract successfully eradicated a non-fatal subcutaneous staphylococcal infection in mice when injected at the site of infection.

Chem Res Toxicol, 1991 Sep-Oct, 4(5), 540 - 5
Structure-activity relationships of bacterial mutagens related to 3-chloro-4-(dichloromethyl)-5-hydroxy-2(5H)-furanone: an emphasis on the effect of stepwise removal of chlorine from the dichloromethyl group; LaLonde RT et al.; The Salmonella typhimurium (TA100) mutagenicities of six structural analogues of 3-chloro-4-(dichloromethyl)-5-hydroxy-2(5H)-furanone (MX) were determined and compared . These were also compared to previously determined mutagenicities for another four analogues . This study was conducted for the primary purpose of ascertaining the effect of C-6 chlorine-by-hydrogen replacement on mutagenicity . The compounds assayed were 3-chloro-4-(chloromethyl)-5-hydroxy-2(5H)-furanone (3), 3-chloro-4-(chloromethyl)-2(5H)-furanone (4), 3-chloro-4-methyl-5-hydroxy-2(5H)-furanone (7), 3-chloro-4-methyl-2(5H)-furanone (8), 4-methyl-5-hydroxy-2(5H)-furanone (9), and 4-methyl-2(5H)-furanone (10) . Compounds 3, 4, and 7 were mutagenic whereas 8-10 were not . All six compounds were stable under assay conditions . Mutagenicity data for the three active compounds were combined with data of another four active compounds studied previously to obtain an expanded data set . Mutagenicities of the seven compounds were compared, pairwise, in 21 comparisons and then by multiple regression analysis . On the average, chlorine-by-hydrogen replacement of a single chlorine located at a chloromethyl group (C-6) had a markedly greater effect in reducing mutagenicity than a similar replacement at C-3 or a hydroxyl-by-hydrogen replacement at C-5 . The chlorine-by-hydrogen replacement at C-6 of compound 3 resulted in the greatest mutagenicity reduction of any single replacement and amounted to a 10(3)-fold diminished mutagenicity.

J Clin Microbiol, 1991 Sep, 29(9), 1899 - 903
Characterization of murine monoclonal antibodies against serogroup B salmonellae and application as serotyping reagents; Tsang RS et al.; Six murine hybridoma monoclonal antibodies reactive with lipopolysaccharide antigens of Salmonella typhimurium were obtained from a fusion of immune spleen cells from mice immunized with S . typhimurium and NS1 myeloma cells . Four antibodies appeared to be specific for serogroup B salmonellae, while the remaining two antibodies were found to be cross-reactive with Salmonella paratyphi A . The exquisite specificities of the Salmonella serogroup B monoclonal antibodies were demonstrated by their unique reactivities with different serotypes of group B salmonellae but with neither other O serogroups of salmonellae nor a wide spectrum of standard strains of other bacterial species . Serotyping of salmonella strains by the slide agglutination method with two of the serogroup B-specific monoclonal antibodies demonstrated their usefulness as serotyping reagents for the identification of serogroup B salmonellae in a routine diagnostic bacteriology laboratory.

Zhonghua Yu Fang Yi Xue Za Zhi, 1991 Sep, 25(5), 292 - 5
{Plasmid pSK1002-mediated mutator effect and SOS response in Salmonella typhimurium and its use for detection of mutagens}; Jin ZC et al.; The plasmid pSK1002 carrying the fused gene umuC'-'lacZ could increase the number of revertants induced by methyl methanesulfonate (MMS) and 4-nitroquinoline-1-oxide (4NQO) in S . typhimurium LT2 TA 1535(his-) . Maximum revertants were 4.35 and 3.96 times that of the controls without the plasmid . The values induced by N-methyl-N'-nitrosoquanidine (MN-NG) were about the same with or without plasmid . However, the plasmid pKM101-mediated mutagenesis-enhancing effect was much greater than that through the mediation of pSK1002 as induced by the three mutagens mentioned above . Moreover, the plasmid pSK1002 could induce umu-mediated SOS response in the presence, of either mutagen stated above and mitomycin C(MMC) . Maximum levels of beta-galactosidase (beta-gal) activity induced by four mutagens respectively were 4.56, 7.14, 4.94, and 3.42 times that of the controls, and a dose-response relationship was evident . The sensitivity of SOS response was superior to mutagenesis-enhancing effect . It showed that pSK1002 (umuC'-'lacZ) had a dual biological effect, namely, mutator effect and the effect of inducing SOS response . Besides, this study has proved SOS mutagenesis of 2,5-dichloronitrobenzol (2,5-DCNB) . Because of the dual indicator nature of pSK1002, it is probable that pSK1002 would be further developed and applied in studying the relation between SOS response and mutagenesis, and monitoring environmental SOS mutagens.

Zhonghua Yu Fang Yi Xue Za Zhi, 1991 Sep, 25(5), 288 - 91
{The co-mutagenic effect of metabolic extracts of fungi grown on the main grain in high incidence liver cancer areas--Fusui County}; Ruan CC; Twenty strains of the common fungi were isolated from the staple grains in the high incidence liver cancer areas--Fusui county, and their metabolic extracts were prepared . Possible co-mutagenic effects of these metabolic extracts on Salmonella typhimurium TA98 and TA100 mutants were tested . The results showed that in vitro these metabolic extracts had different degrees of co-mutagenic effects . It is considered that these co-mutagenic effects may play an important role in the incidence of liver cancer in Fusui county.

J Biochem (Tokyo), 1991 Sep, 110(3), 462 - 7
Purification and properties of cloned Salmonella typhimurium LT2 sialidase with virus-typical kinetic preference for sialyl alpha 2----3 linkages; Hoyer LL et al.; Subclones containing the Salmonella typhimurium LT2 sialidase gene, nanH, were expressed in Escherichia coli from multicopy derivatives of pBR329 . The cloned sialidase structural gene directed overproduction of sialidase polypeptide which was detected as the major soluble protein species in cell-free extracts . Overproduced enzyme was purified to near electrophoretic homogeneity after 65-fold enrichment using conventional preparative techniques . Unlike all previously investigated sialidases, S . typhimurium sialidase was positively charged (pI greater than or equal to 9.0) . Km, Vmax, and turnover number of the purified sialidase, measured using 2'-(4-methylumbelliferyl)-alpha-D-N-acetylneuraminic acid (MUNeu5Ac), were 0.25 mM, 5,200 nmol min-1, and 2,700 s-1, respectively . These values are the highest yet reported for a sialidase . Sialidase was inhibited by 2-deoxy-2,3-didehydro-N-acetyl-neuraminic acid at unusually high concentrations (Ki = 0.38 mM), but not by 20 mM N-acetylneuraminic acid . Divalent cations were not required for activity . The pH optimum for hydrolysis of MUNeu5Ac was between 5.5 and 7.0 and depended on the assay buffer system . Substrate specificity measurements using natural sialoglycoconjugates showed a 260-fold kinetic preference for sialyl alpha 2----3 linkages when compared with alpha 2----6 bound sialic acids . The enzyme also efficiently cleaved residues from glycoproteins and gangliosides, but not from mucin or sialohomopolysaccharides . S . typhimurium sialidase is thus the first bacterial enzyme to be described with influenza A virus sialidase-like kinetic preference for sialyl alpha 2----3 linkages and to have a basic pI.

Mol Microbiol, 1991 Sep, 5(9), 2261 - 4
Cloning of a sequence of Aquaspirillum magnetotacticum that complements the aroD gene of Escherichia coli; Berson AE et al.; A 2 kb DNA fragment isolated from a cosmid library of Aquaspirillum magnetotacticum strain MS-1 complements the aromatic-metabolite requirements and iron-uptake deficiencies of Escherichia coli and Salmonella typhimurium strains that lack a functional aroD (biosynthetic dehydrodquinase) sequence . All recombinant cosmids selected for their aroD complementation property carry this sequence . No DNA sequence homology has, however, been detected by Southern hybridization between the cloned fragment and the aroD gene of E . coli or the qa2 (catabolic dehydroquinase) gene of Neurospora crassa.

Mol Microbiol, 1991 Sep, 5(9), 2073 - 8
PhoP/PhoQ: macrophage-specific modulators of Salmonella virulence?
Miller SI.
The regulation of gene expression by the two-component regulatory system PhoP/PhoQ is necessary for Salmonella typhimurium survival within macrophages, defensin resistance, acid resistance, and murine typhoid fever pathogenesis . Salmonella experience multiple environments during mammalian infection and survival requires tightly regulated gene expression . After phagocytosis by macrophages, signal transduction by PhoQ results in the transcription of phoP-activated genes (pags) encoding proteins essential to bacterial survival and virulence . One such gene, pagC, encodes an envelope protein with amino acid similarity to an epithelial cell invasion protein of Yersina enterocolitica, Ail, and a bacteriophage lambda outer membrane protein, Lom . The PhoP and PhoQ proteins can also repress the synthesis of proteins, encoded by phoP repressed genes (prgs), when pags are maximally expressed . If prgs encode receptors for toxic compounds, prg repression may protect the cell within macrophages when pag expression is most necessary . At least one prg locus, prgH, is required for full S . typhimurium mouse virulence . Within the macrophage, different environments may stimulate a switch from pag to prg expression that is necessary to Salmonella survival . prg expression may also be necessary for surviving nonmacrophage environments . Study of the PhoP regulon should lead to the discovery of new virulence factors, increase knowledge of how gene regulation is essential to bacterial virulence, and perhaps lead to the development of better vaccines for typhoid fever.

Biomed Environ Sci, 1991 Sep, 4(3), 310 - 6
Studies on the mutagenicity of hair dyes made in China; Wang LL et al.; A total of 13 commercial hair dye products made in China were tested for mutagenicity in 2 short-term bioassays, the histidine-requiring mutants of Salmonella typhimurium (strains TA98 and TA100) and the micronucleus test with mouse bone-marrow polychromatic erythrocyte cells in vivo . The results showed that the 13 hair dyes were not mutagenic in strains TA98 and TA100 with and without S-9 . In the micronucleus test, no mutagenic effect was observed.

Mol Microbiol, 1991 Sep, 5(9), 2233 - 41
The sugar-specific outer membrane channel ScrY contains functional characteristics of general diffusion pores and substrate-specific porins; Schulein K et al.; Escherichia coli K-12 strain PS1-28-37 carries the multicopy plasmid pPSO28-37 containing a DNA fragment coding for two of the proteins that enable bacteria to utilize sucrose as sole carbon source . One of the different gene products of the plasmid is the outer membrane protein, ScrY . This protein was isolated and purified by chromatography across a gel filtration column . Reconstitution experiments with lipid bilayer membrane demonstrated that ScrY formed ion-permeable channels with properties very similar to those of general diffusion pores of enteric bacteria . The presence of sugars in the aqueous phase led to a dose-dependent block of ion transport through the channel, like the situation found with LamB (maltoporin) of Escherichia coli and Salmonella typhimurium . The binding constants of a variety of different sugars were determined . The stability constant for malto-oligosaccharide binding increased with increasing numbers of glucose residues . Disaccharides generally had a larger binding constant than monosaccharides . The binding of different sugars to ScrY and LamB of E . coli is discussed with respect to the kinetics of sugar movement through the channel.

Mutat Res, 1991 Sep, 261(1), 51 - 6
Structure-activity relationships of a series of antitumoral 5,8-quinazolinediones in mutagenicity studies; Callais F et al.; Four antitumoral 5,8-quinazolinediones were examined for their ability to induce mutation in Salmonella typhimurium . Each compound was tested at several concentrations in 4 strains . Relationships were established between the structure of the quinones and their mutagenic activities . The mutagenicity was influenced by (i) the nature of the substituent(s) of the quinonic moiety: the methoxyquinone had no mutagenic properties and the aziridinylquinones were mutagenic in the 4 strains with or without activation by S9 mix; (ii) the presence or the absence of a diaminopolymethylenic chain in the 4 position; (iii) the monomeric or the dimeric structure of the tested compound . Interestingly, the data indicated that the aziridinylquinazolinedione bearing the dimethylaminopropylamino chain in the 4 position was less mutagenic and had greater antitumor activity than the dimeric quinone.

J Immunol, 1991 Sep 1, 147(5), 1647 - 52
Selection of the same major T cell determinants of influenza nucleoprotein after vaccination or exposure to infectious virus; Brett SJ et al.; In the present study, we have compared the T cell antigenic determinants on nucleoprotein (NP) of influenza A/NT/60/68 virus recognized by BALB/c mice (H-2d) after vaccination using several different vehicles with the determinants recognized after exposure to infectious virus . Mice were immunized s.c . with: 1) purified recombinant NP with three different adjuvants--alum, saponin, or CFA; 2) whole inactivated A/Okuda virus in PBS or saponin; or 3) live attenuated Salmonella typhimurium AroA- vector expressing NP . A series of overlapping synthetic peptides that cover more than 90% of the amino acid sequence of NP were used to map the Th cell epitopes . The results showed that the same limited number of major epitopes were recognized after each of the different immunization regimes . Secondary in vivo boosting using the same vehicles as for the primary immunization did not increase the number of different T cell sites recognized . The T cell responses after intranasal infection with infectious A/NT/60/68 or A/PR/8/34 virus also showed a similar pattern of recognition of the major CD4-positive T cell epitopes . The only exception was that the region corresponding to residues 401-419 was only recognized after exposure to NP from A/NT/60/68 but not A/PR/8/34 . This is probably because the two viruses differ in amino acid sequence at positions 408 and 411 within this part of the NP molecule . In contrast to the results observed with CD4-positive T cell epitopes, the major determinant recognized by CD8-positive T cells was only presented after live viral infection . The results in this study have important implications for vaccine design, inasmuch as they indicate that the same dominant CD4 T cell determinants on NP presented by vaccination with NP are also recognized by T cells from mice exposed to infectious virus.

Zentralbl Veterinarmed B, 1991 Sep, 38(7), 545 - 51
Slime capsule and fimbriae on Salmonella typhimurium var . cop.--electron microscopic study; Grund S; On Salmonella typhimurium var . cop . we found, under special culture conditions, on the same cell simultaneously fimbriae and mucoid material which was histochemically identified as an acid mucopolysaccharide . Membrane vesicles or invaginations of the cytoplasmic membrane are mentioned as a possible place of the slime production and the function of the glycocalyx is discussed regarding tenacity, as a diffusion barrier and attachment factor.

Parasite Immunol, 1991 Sep, 13(5), 517 - 30
Inability of Plasmodium vinckei-immune spleen cells to transfer protection to recipient mice exposed to vaccine 'vectors' or heterologous species of plasmodium; Winkel KD et al.; Mice can be immunized to Plasmodium vinckei by repeated infections followed by cure . Such immunity is dependent on CD4 T cells and an architecturally modified spleen, but has little requirement for antibody . Thus, athymic mice can be exposed to P . vinckei and cured, but do not develop immunity . They are resistant to challenge with parasites, however, if they are then given spleen cells from euthymic immunized animals . Such immune spleen cells, however, cannot transfer resistance to normal mice which have been exposed to BCG, Salmonella typhimurium, or vaccinia virus, and are only partially effective in transferring resistance to mice which have been previously immunized with heterologous plasmodia, P . yoelii, P . chabaudi and P . berghei . Mice exposed to varying numbers of irradiated P . vinckei-pRBC do not develop immunity and nor are such animals protected following adoptive transfer of immune spleen cells . Cellular immunity to malaria may not only be dependent on a population of immune CD4 T cells, but may require a specifically architecturally modified spleen which may not occur following either exposure to candidate vaccine vectors, heterologous plasmodia or non-viable homologous plasmodia.

EMBO J, 1991 Sep, 10(9), 2707 - 15
Altering the conserved nucleotide binding motif in the Salmonella typhimurium MutS mismatch repair protein affects both its ATPase and mismatch binding activities; Haber LT et al.; The Salmonella typhimurium and Escherichia coli MutS protein is one of several methyl-directed mismatch repair proteins that act together to correct replication errors . MutS is homologous to the Streptococcus pneumoniae HexA mismatch repair protein and to the Duc1 and Rep1 proteins of human and mouse . Homology between the deduced amino acid sequence of both MutS and HexA, and the type A nucleotide binding site consensus sequence, suggested that ATP binding and hydrolysis play a role in their mismatch repair functions . We found that MutS does indeed weakly hydrolyze ATP to ADP and Pi, with a Km of 6 microM and kcat of 0.26 . To show that this activity is intrinsic to MutS, we made a site-directed mutation, which resulted in the invariant lysine of the nucleotide binding consensus sequence being changed to an alanine . The mutant MutS allele was unable to complement a mutS::Tn10 mutation in vivo, and was dominant over wild type when present in high copy number . The purified mutant protein had reduced ATPase activity, with the Km affected more severely than the kcat . Like the wild type MutS protein, the mutant protein is able to bind heteroduplex DNA specifically, but the mutant protein does so with a reduced affinity.

Gene, 1991 Aug 30, 105(1), 37 - 42
Cloning and characterization of the L-rhamnose regulon in Salmonella typhimurium LT2; Nishitani J et al.; A Salmonella typhimurium LT2 cosmid library was constructed, and a 46-kb recombinant plasmid was isolated that could complement an Escherichia coli rha mutant . Subsequent subcloning generated a 13.6-kb ClaI restriction fragment that contained a functional regulatory element . By complementation analyses using different subclones, the approximate physical locations of rhaT, rhaC1, rhaC2, rhaB, rhaA, and rhaD were determined . The nucleotide sequence spanning the rhaB and rhaC2 genes was determined.

Biochem Biophys Res Commun, 1991 Aug 15, 178(3), 934 - 9
Evidence for isoleucine as a positive effector of the ilvBN operon in Salmonella typhimurium; Davidson JP et al.; Concerted efforts were directed towards understanding the control of acetohydroxy acid synthase (AHAS) in the gyrB mutant hisU1820 of Salmonella typhimurium . A media shift from valine to valine plus isoleucine causes a dramatic 4 to 5 fold burst of AHAS valine sensitive activity which appears to be dependent on translation . DJ19, an isolated valine sensitive derivative of the gyrB mutant, maintains a dramatic increase in AHAS valine sensitive activity upon the addition of isoleucine to valine supplemented cultures, suggesting that the isoleucine effect is specific for valine sensitive AHAS . Evidence supports isoleucine as a positive effector on valine sensitive AHAS expression and that the gyrB mutation accentuates the isoleucine effect.

J Trop Pediatr, 1991 Aug, 37(4), 172 - 5
Bacteriology of acute septic arthritis; Nduati RW et al.; In a study of septic arthritis infants formed the bulk of patients though, notably, neonates were not encountered . Gram-negative bacterial of the Salmonella species, especially Salmonella typhimurium and Klebsiella species were the most important cause of septic arthritis in infants . Staphylococcus aureus was also isolated . The combination of blood cultures and joint aspirate cultures resulted in very high rate (72 per cent) of bacteria isolation . It is strongly recommended that every effort should be made to obtain two bacteriological specimens for culture to improve bacteriological diagnosis of the disease.

Wei Sheng Wu Xue Bao, 1991 Aug, 31(4), 315 - 7
{Regulation of riboflavin biosynthesis in Salmonella typhimurium}; Wang AQ; 7 independent rib genes fusions with MudJ (lacZ, Kanr) were isolated by transposon MudJ mutagenesis in Salmonella typhimurium . 5 of them are blue on the X-gal plate, and the beta-galactosidase activity of the cells grown in E medium containing various concentration of riboflavin were assayed . The results showed that the expression of rib gene are not repressed by riboflavin . It appears to be synthesized constitutively in Salmonella typhimurium.

FEMS Microbiol Immunol, 1991 Aug, 3(4), 229 - 39
Requirement of the conformational stability of a Salmonella ribosomal vaccine for its mouse protection; Kita E et al.; The 43-kDa non-O antigenic component isolated from the crude ribosomal fraction of Salmonella typhimurium {9} was further purified by affinity chromatography (43-kDa protein: 43-kDp) . Immunization with 43-kDp did not induce complete mouse protection in CF1 mice to 500 LD50 of S . typhimurium, although it elicited a substantial IgG antibody response . The 43-kDp exhibited the mitogenicity to splenocytes (CF1 and C3H/HeJ) and B cell-rich populations (CF1) . Complexing 43-kDp with the compact ribosomes of Streptococcus pyogenes by formaldehyde (complex vaccine: CV) elicited both IgM and IgG antibodies to 43-kDp . CV induced a boosting effect to enhance IgG antibody response . Moreover, CV generated delayed-type hypersensitivity to salmonella antigens and also conferred complete protection against 500 LD50 challenge of S . typhimurium to CF1 mice . These abilities of CV were reduced or impaired by RNase digestion . CV was able to induce partial or complete protection in inbred mouse strains (C3H/HeN, C3H/HeJ, DBA/2 and A/J) . These data, in addition to other reports, suggest that conformational stability between ribosomes and contaminating substances such as 43-kDp or O-antigens might be required for the overall effects of the ribosomal vaccine.

Cancer Lett, 1991 Aug, 59(2), 89 - 94
Effect of allixin, a phytoalexin produced by garlic, on mutagenesis, DNA-binding and metabolism of aflatoxin B1; Yamasaki T et al.; Allixin, a phytoalexin isolated from garlic, was examined for its effects on aflatoxin B1(AFB1)-induced mutagenesis using Salmonella typhimurium TA100 as the bacterial tester strain and rat liver S9 fraction as the metabolic activation system . The effects of allixin on the binding of {3H}AFB1 to calf thymus DNA and on the formation of metabolites of {3H}AFB1 were also determined . Allixin showed a dose-related inhibition of Histidine+ revertants induced by AFB1 . Allixin at 75 micrograms/ml inhibited {3H}AFB1 binding to calf thymus DNA and reduced formation of AFB1-DNA adducts . In addition, allixin exhibited a concentration-dependent inhibition of the formation of organosoluble metabolites and the glutathione conjugates of {3H}AFB1 . The data indicate that the effect of allixin on AFB1-induced mutagenesis and binding of metabolites to DNA may be mediated through an inhibition of microsomal P-450 enzymes . Allixin may thus be useful in the chemoprevention of cancer.

Infect Immun, 1991 Aug, 59(8), 2822 - 7
Selective induction of metabolic activation programs in peritoneal macrophages by lipopolysaccharide substructures; Lehmann V et al.; The structural elements of Salmonella typhimurium lipopolysaccharides (LPS) that are able to stimulate peritoneal macrophages to produce increased amounts of prostaglandin E2, ornithine, and citrulline, agents known to modulate immune responses, are described . Two different incomplete lipid A structures which lack the carbohydrate portion, the nonhydroxylated fatty acids lauric acid and myristic acid (lipid A precursor IB), and additional palmitic acid (lipid A precursor IA) stimulated increased prostaglandin E2 synthesis but were unable to augment ornithine and citrulline production at concentrations of up to 0.5 microgram/ml . Acyl-deficient smooth LPS containing lipid A precursors IA and IB substituted by the complete carbohydrate region were able to augment prostaglandin E2 and ornithine production but failed, even at a high concentration (0.5 microgram/ml), to stimulate citrulline production . Moreover, Re glycolipids and smooth intact LPS containing the lipid A region with 3-acyloxyacyl residues possessed all of the structural requirements to induce increased prostaglandin E2, ornithine, and citrulline synthesis . Finally, all of the LPS structures, including lipid A precursors IA and IB stimulated, in combination with gamma interferon, production of citrulline with similar efficiencies . These results demonstrate that LPS contains various substructures including regions of the carbohydrate and lipid A structure that can deliver signals for the activation of peritoneal macrophages . Signals for partial activation of macrophages to produce prostaglandins and ornithine can be delivered by acyl-deficient LPS structures . In contrast, full activation of macrophages to produce citrulline requires an additional signal that is delivered by 3-acyloxyacyl residues of the lipid A region or gamma interferon.

Food Chem Toxicol, 1991 Aug, 29(8), 575 - 8
Maleic acid dimethylester: evaluation of dermal toxicity and genotoxicity; Heimann KG et al.; Maleic acid dimethylester (MAD) was investigated in acute and subacute dermal toxicity studies, for sensitization potential, and for in vivo and in vitro genotoxicity . The acute dermal toxicity in rats was low (LD50 greater than 2000 mg/kg body weight) . Only local effects, erythema and necrosis, occurred at the site of application . Corresponding dose-related effects were observed in a 28-day repeated dermal toxicity study in rats . Treatment-related systemic alterations were observed in feed consumption, body weights, haematology and clinical chemistry at 170 and 500 mg MAD/kg body weight . Based on the results of this study, the no-toxic-effect level of MAD was considered to be 60 mg/kg body weight/day . However, slight dermal irritative effects were also present at the lowest dose level (60 mg/kg body weight) . The primary skin irritation test in rabbits showed only slight erythema and oedema . The results of the maximization test in guinea-pigs indicated a clear sensitizing potential of MAD . In the Ames test, with five strains of Salmonella typhimurium, MAD was not mutagenic up to the highest dose level of 5000 micrograms/plate . In the micronucleus test, in which mice were given 1000 mg MAD/kg body weight by gavage the compound revealed no clastogenic effects.

Food Chem Toxicol, 1991 Aug, 29(8), 517 - 22
Detection of IQ-type mutagens in canned roasted eel; Lee H et al.; Basic extracts of canned roasted eel exhibited the highest mutagenicity among seven kinds of canned products assayed with Salmonella typhimurium TA98 in the presence of S-9 mix . The major mutagenic compounds of canned roasted eel extracts were purified and analysed by HPLC . The mutagenic fractions corresponding to the peaks of standard 2-amino-3,8-dimethylimidazo{4,5-f}quinoxaline(MeIQx) and 2-amino-3,7,8-trimethylimidazo{4,5-f}quinoxaline(7,8-DiMeIQx ) were further confirmed by the comparison of UV spectra, tester strain specificity and nitrite treatment . The estimated contents of MeIQx and 7,8-DiMeIQx were 1.1 ng and 5.3 ng per gram of canned roasted eel, respectively . Cooking temperature and time seemed to be the major factors affecting mutagen formation in fried eel . The type and amount of mutagenic compounds detected in canned roasted eel are likely to be correlated with the relative levels of specific free amino acids in raw eel.

J Trop Med Hyg, 1991 Aug, 94(4), 253 - 60
The relationship of microbial pathogens to acute infectious diarrhoea of childhood; Mathew M et al.; Bacterial, viral and parasitic enteric pathogens were detected in 692 of 916 children below 36 months of age with acute diarrhoea and in 289 of 587 matched controls . The rates of identification of only four groups of pathogens, rotavirus, Shigellae, Salmonella typhimurium and enterotoxigenic E . coli, were significantly higher in the patients . The prevalence of a variety of other enteric pathogens was similar in controls of patients . Shigellosis had a characteristic clinical profile but none of the other agents could be suspected on clinical grounds . The high prevalence of pathogens in controls suggested that the population may be partially protected against a variety of enteric pathogens and that final common pathways leading to diarrhoea may be activated by changes in the microbial ecology of the gut lumen.

Epidemiol Infect, 1991 Aug, 107(1), 213 - 23
Gentamicin-resistant Salmonella typhimurium phage type 204c: molecular studies and strain diversity in a putative bovine outbreak; Platt DJ et al.; As part of the investigation of a putative bovine outbreak, 13 isolates of Salmonella typhimurium phage type 204c were subjected to plasmid analysis . Plasmid profiles suggested that several distinct strains were involved and these observations were supported by minor variations in antibiotic resistance pattern . Restriction enzyme fingerprinting and conjugational segregation of the plasmids confirmed these findings . Although 12 of the 13 isolates were resistant to gentamicin, resistance was conferred by 4 distinct plasmids; 3 of these belonged to Inc I and were distantly related on the basis of restriction fingerprints and the fourth was a resistant derivative of the 60 MDa S . typhimurium serotype-specific plasmid . The molecular evidence refuted the hypothesis that geographical and temporal clustering of these gentamicin-resistant isolates could be explained on the basis of a single epidmiological episode.

Mutat Res, 1991 Aug, 260(4), 321 - 9
Bacterial mutagenicity testing of 49 food ingredients gives very few positive results; Prival MJ et al.; 49 substances permitted for use in food in the United States was tested for mutagenicity in the Ames Salmonella typhimurium assay and in Escherichia coli strain WP2 . Four of these substances caused increases in revertant counts in S . typhimurium . Two of these four (papain and pepsin) were found to contain histidine, and therefore the results of the tests on these two substances could not be taken as demonstrating mutagenicity . The other two substances causing increases in revertant counts (hydrogen peroxide and potassium nitrite) were mutagenic . The results on one chemical, beta-carotene, were evaluated as inconclusive or questionable . The remaining 44 substances were nonmutagenic in the test systems used . It is concluded that, for those generally physiologically innocuous chemicals tested, there are very few 'false positives' in the bacterial test systems used.

Mutat Res, 1991 Aug, 253(1), 97 - 102
Mutagenic properties of 2-amino-N6-hydroxyadenine in Salmonella and in Chinese hamster lung cells in culture; Nagao M et al.; The mutagenicity of the base analogue, 2-amino-N6-hydroxyadenine (AHA), was tested in Salmonella typhimurium TA100 and TA98 and in Chinese hamster lung (CHL) cells . AHA showed very potent mutagenicity in TA100 without S9 mix, inducing 25,000 revertants/micrograms . The mutagenicity increased about 2-fold upon addition of S9 mix containing 10 microliters S9 . AHA was found to be one of the strongest mutagens for TA100 . Addition of S9 mix containing 100 microliters S9 induced no significant increase of revertants with AHA at amounts up to 50 ng per plate . AHA was also mutagenic for the frameshift mutant, TA98, without S9 mix, the mutagenicity for TA98 being about 1/1000 of that for TA100 . When the mutagenicity of AHA was tested in CHL cells, with diphtheria toxin resistance (DTr) as a selective marker in the absence of S9 mix with a 3-h treatment of cells, DTr mutants increased dose-dependently at concentrations of 2.5-15 micrograms/ml . When cells were incubated with AHA for 24 h, a 200-fold increase in the number of DTr mutants was observed; the mutagenicity was 500-fold higher than that of ethyl methanesulfonate . This marked increase of mutagenicity by prolonged incubation may indicate that AHA induces mutations mainly after incorporation into DNA . The addition of a small amount of S9 increased the mutagenicity obtained with a 3-h treatment 2-fold, but a larger amount of S9 decreased the mutagenicity as was found with S . typhimurium TA100.

Mutat Res, 1991 Aug, 253(1), 33 - 46
The genetic activity of N6-hydroxyadenine and 2-amino-N6-hydroxyadenine in Escherichia coli, Salmonella typhimurium and Saccharomyces cerevisiae; Pavlov YI et al.; The genetic activity of 2-amino-N6-hydroxyadenine or 2-amino-N-hydroxylaminopurine (AHA) and N6-hydroxyadenine or 6-N-hydroxylaminopurine (HAP) was studied in S . typhimurium, E . coli and Saccharomyces cerevisiae strains . AHA was a more potent mutagen for bacteria and a less potent mutagen for yeast than HAP . The mutagenic activity of analogs was not influenced by excision, mutagenic or double-strand DNA repair mutations . On the other hand, the uvrBdel mutation has a drastic effect on the mutagenicity and toxicity of both analogs in the Salmonella strains studied . HAP was a very potent mutagen in yeast with a low capability of inducing mitotic recombination contrary to common mutagens, possessed unique intergenic specificity and was able to induce mutations in diploids at rather high frequency.

Mutat Res, 1991 Aug, 263(4), 249 - 55
Activation of some aromatic amines to mutagenic products by human red blood cell cytosol; Duverger-van Bogaert M et al.; The ability of human red blood cell cytosol to activate aromatic amines was evaluated with the Ames test using Salmonella typhimurium TA98 in the liquid preincubation condition . While negative results were obtained with 4-acetylaminofluorene (4AAF) and 1-naphtylamine (1NA), a slight response was observed for 4-aminobiphenyl (4ABP) and 2-naphthylamine (2NA) . Human red blood cell cytosol was able to activate 2-aminofluorene (2AF), 2-acetylaminofluorene (2AAF) and 2-aminoanthracene (2AA) to mutagenic intermediates . Extracts of human red blood cell cytosol incubated with 2AF were analyzed by gas chromatography: N-hydroxy-2-aminofluorene was identified as a metabolite.

Mutat Res, 1991 Aug, 263(4), 203 - 10
Cycloheximide genotoxicity in in vitro and in vivo test systems; Basic-Zaninovic T et al.; The aim of this study was to investigate if there was any genotoxic effect produced by the antibiotic cycloheximide, widely used as a fungicide in agriculture as well as in everyday laboratory practice . The battery of test systems included the bacterium Salmonella typhimurium (strains TA98 and TA100), the yeast Saccharomyces cerevisiae (D7), Allium cepa somatic cells and mouse bone marrow cells . This combination of test systems enabled us to establish possible effects caused by cycloheximide at different levels of the genome and to indicate a possible mechanism of action . The results obtained in experiments showed that cycloheximide did not induce frameshift or base-pair substitution mutations in S . typhimurium regardless of metabolic activation . In S . cerevisiae cycloheximide had only toxic effects but no increase of mitotic gene conversion was noticed under the conditions of the experiment . However, in A . cepa somatic cells as well as in mouse bone marrow cells cycloheximide showed its activity causing different genetic damages, e.g., chromosome breaks, mitotic disturbances and nuclear abnormalities.

J Bacteriol, 1991 Aug, 173(16), 5188 - 93
Suppression of the abnormal phenotype of Salmonella typhimurium rfaH mutants by mutations in the gene for transcription termination factor Rho; Farewell A et al.; Mutations in the rfaH gene have previously been shown to cause premature termination of transcription of the traYZ operon of the F factor and also to prevent expression of the rfaGBIJ gene cluster of Salmonella typhimurium . In the present study, mutants were selected for their ability to restore the normal pattern of rfaGBIJ function . On the basis of this initial section, several classes of extragenic suppressor mutants were isolated that completely or partially corrected the Tra- and Rfa- phenotypes of the prototype rfaH mutant . The suppressor mutations included mutations in rho and mutations that mapped in or close to rpoBC . Other suppressor mutations were located elsewhere on the chromosome, presumably identifying other genes that play a role in the RfaH-mediated transcriptional regulation.

J Bacteriol, 1991 Aug, 173(16), 5168 - 72
Identification and initial characterization of the eutF locus of Salmonella typhimurium; O'Toole GA et al.; We report the isolation and initial characterization of mutations in the newly described eutF locus of Salmonella typhimurium LT2 . Mutations in eutF render a strain unable to utilize ethanolamine as a source of carbon and/or energy and impair growth on ethanolamine as a sole nitrogen source . Strains carrying eutF mutations exhibit a 2-order-of-magnitude decrease in transcription of the unlinked eutDEABCR operon (50 min), which codes for the enzymes needed to catabolize ethanolamine; have only 10% of the ethanolamine ammonia-lyase activity found in the wild type; and show a marked reduction in the rate of ethanolamine uptake . Deletion mapping and three-factor cross analysis results are consistent with the gene order cobA trp eutF tonB at 34 min on the linkage map . We discuss two possible roles for the EutF protein: (i) as an ethanolamine permease or (ii) as a transcription factor required for the expression of the eutDEABCR operon.

J Bacteriol, 1991 Aug, 173(16), 5230 - 3
Analysis of the host ranges of transposon bacteriophages Mu, MuhP1, and D108 by use of lipopolysaccharide mutants of Salmonella typhimurium LT2; Roncero C et al.; The lipopolysaccharide receptors for the mutator bacteriophages Mu, MuhP1, and D108 were investigated with lipopolysaccharide mutants of Salmonella typhimurium LT2 . Mu adsorbed only to mutants lacking the terminal O antigen but retaining the main chain sugars of the core; the side chain N-acetylglucosamine was not required . MuhP1 and D108 adsorbed partially to cells with the same receptors but adsorbed well only to cells with shorter lipopolysaccharides of the Rc and Rd1 chemotypes.

Indian J Exp Biol, 1991 Aug, 29(8), 730 - 7
Mutagenic activity of south Indian food items; Sivaswamy SN et al.; Dietary components and food dishes commonly consumed in South India were screened for their mutagenic activity . Kesari powder, calamus oil, palm drink, toddy and Kewra essence were found to be strongly mutagenic; garlic, palm oil, arrack, onion and pyrolysed portions of bread toast, chicory powder were weakly mutagenic, while tamarind and turmeric were not . Certain salted, sundried and oil fried food items were also mutagenic . Cissus quadrangularis was mutagenic, while 'decoctions' of cumin seeds, aniseeds and ginger were not . Several perfumes, essential oils and colouring agents, which are commonly used were also screened and many of them exhibited their mutagenic potential by inducing the 'reverse mutation' in Salmonella typhimurium tester strains.

Mol Microbiol, 1991 Aug, 5(8), 1903 - 13
A Bacillus subtilis dipeptide transport system expressed early during sporulation; Mathiopoulos C et al.; Two previously identified Bacillus subtilis DNA segments, dciA and dciB, whose transcripts accumulate very rapidly after induction of sporulation, were found in the same 6.2 kb transcription unit, now known as the dciA operon . Analysis of the sequence of the dciA operon showed that its putative products are homologous to bacterial peptide transport systems . The product of the fifth gene, DciAE, is similar to peptide-binding proteins from Escherichia coli and Salmonella typhimurium (DppA and OppA) and B . subtilis (OppA) . A null mutation in dciAE abolished the ability of a proline auxotroph to grow in a medium containing the dipeptide Pro-Gly as sole proline source, suggesting that the dciA operon encodes a dipeptide transport system.

J Autoimmun, 1991 Aug, 4(4), 607 - 15
Identification of the main epitope on human cytochrome P450 IID6 recognized by anti-liver kidney microsome antibody; Gueguen M et al.; Antibodies present in the sera of a group of children with autoimmune hepatitis react with human cytochrome P450 IID6 . cDNA constructions of various fragments of human P450 IID6 were made and expressed and the resulting peptides were tested in immunoblot with patients' sera . These allowed identification of at least two antigenic sites on the P450 molecule . The main one, recognized by all sera tested, is located between amino acids 239 and 271 . Synthesis of three peptides covering this area of the molecule allowed identification of a sequence of three amino acids (tyrosine-tryptophane-asparagine) located at position 261-263 that constitutes the essential part of the epitope . A protein sequence data-base search revealed homologies between this region of human P450 and proteins from Salmonella typhimurium, from human T lymphotropic virus types 1 and 2 and Herpes simplex virus type 1.

J Bacteriol, 1991 Aug, 173(15), 4765 - 72
Type 1 fimbriae of Salmonella enteritidis; Muller KH et al.; Salmonella enteritidis was previously shown to produce fimbriae composed of 14,000-molecular-weight (Mr) fimbrin monomers (J . Feutrier, W . W . Kay, and T . J . Trust, J . Bacteriol . 168:221-227, 1986) . Another distinct fimbrial structure, comprising 21,000-Mr fimbrin monomers, has now been identified . These fimbriae are simply designated as SEF 14 and SEF 21, respectively (for S . enteritidis fimbriae and the Mr {in thousands} of the fimbrin monomer) . A simple method for the purification of both structures was developed by using the different biochemical properties of these fimbriae . SEF 21 remained intact after being boiled in sodium dodecyl sulfate but readily dissociated into subunits of 21,000 Mr at pH 2.2 . The overall amino acid composition and the N-terminal amino acid sequence of the SEF 21 fimbrin were distinct from those of SEF 14 but were virtually identical to the predicted sequence for type 1 fimbrin of Salmonella typhimurium . Immunoelectron microscopy of S . enteritidis clearly revealed fimbrial structures that reacted with immune serum specific to the 21,000-Mr fimbrin . Immune sera raised against this subunit were cross-reactive with type 1 fimbrins found in whole-cell lysates of S . typhimurium, Salmonella illinois, and Salmonella cubana . However, there was no cross-reaction with Escherichia coli type 1 fimbriae or with other fimbrins produced by S . enteritidis . Under certain growth conditions, S . enteritidis produced both SEF 14 and SEF 21 . However, when S . enteritidis was grown at 30 degrees C or lower, only the 21,000-Mr SEF 21 fimbrin could be detected . There was a direct correlation between mannose-sensitive hemagglutination and the presence of SEF 21.

J Bacteriol, 1991 Aug, 173(16), 5129 - 35
Inducible pH homeostasis and the acid tolerance response of Salmonella typhimurium; Foster JW et al.; The acid tolerance response (ATR) is an adaptive system triggered at external pH (pHo) values of 5.5 to 6.0 that will protect cells from more severe acid stress (J . Foster and H . Hall, J . Bacteriol . 172:771-778, 1990) . Correlations between the internal pH (pHi) of adapted versus unadapted cells at pHo of 3.3 indicate that the ATR system produces an inducible pH-homeostatic function . This function serves to maintain the pHi above 5 to 5.5 . Below this range, cells rapidly lose viability . Development of this pH homeostasis mechanism was sensitive to protein synthesis inhibitors and operated only to augment the pHi at pHo values below 4 . In contrast, classical constitutive pH homeostasis was insensitive to protein synthesis inhibitors and was efficient only at pHo values above 4 . Physiological studies indicated an important role for the Mg(2+)-dependent proton-translocating ATPase in affording ATR-associated survival during exposure to severe acid challenges . Along with being acid intolerant, cells deficient in this ATPase did not exhibit inducible pH homeostasis . We speculate that adaptive acid tolerance is important to Salmonella species in surviving acid encounters in both the environment and the infected host.

Gene, 1991 Jul 31, 104(1), 123 - 4
The nucleotide sequence of rpsL and its flanking regions in Salmonella typhimurium; Hughes D et al.; The ribosomal protein (r-protein)-encoding gene, rpsL, and regions flanking it, from Salmonella typhimurium, have been sequenced directly from polymerase chain reaction-amplified chromosomal DNA . The deduced amino acid sequence is identical to that of the Escherichia coli rpsL encoded r-protein . At the nucleotide level, the similarity is 98%, suggesting a strong pressure for the conservation of this important protein . More surprisingly, the noncoding sequences surrounding the gene are also conserved at the 98% level, suggesting that they too are functionally important.

Gene, 1991 Jul 15, 103(1), 135 - 6
Sequence of the phosphomannose isomerase-encoding gene of Salmonella typhimurium; Collins LV et al.; The pmi gene, encoding phosphomannose isomerase, of Salmonella typhimurium, was cloned in Escherichia coli K-12, and the protein product visualised in minicells . The cloned gene was sequenced; there was 77.4% nucleotide homology between the cloned pmi gene and the analogous manA gene of E . coli K-12, and 86.2% amino acid sequence homology between their presumptive gene products.

J Mol Biol, 1991 Jul 5, 220(1), 79 - 88
Point mutations that lock Salmonella typhimurium flagellar filaments in the straight right-handed and left-handed forms and their relation to filament superhelicity; Hyman HC et al.; We have determined the nucleotide sequence of two mutant and the parent fliC genes, encoding the protein flagellin (serotype i), of Salmonella typhimurium . The flagellar filaments of the two mutants, SJW1655 and SJW1660, are locked in the straight-right-handed (R) and straight-left-handed (L) conformations, respectively . Their normal, wild-type, parent strain is SJW1103 . These mutant strains differ from the wild-type by only one base-pair: the mutation of SJW1655 occurs at nucleotide 1346 in the flagellin gene, changing a C.G pair to T.A (alanine 449 to valine) . The mutation of SJW1660 occurs at nucleotide 1277, changing a G.C pair to C.G (glycine 426 to alanine) . The resulting amino acid substitutions are near the C terminus predicted to form an alpha-helical coiled coil . The region contains six heptad repeats . Similar alpha-helical segments (three and four repeats long) are present near the N terminus . Alignment of the 17 flagellin sequences available to date confirms the generality of these segments . The mutations are within that portion of the sequence assigned, by proteolytic cleavage, to the middle flagellin domain whose length corresponds to the six heptad repeats found in the sequence (approximately 50 A) . We have shown that these mutations are the sole cause of the straight phenotype by replacing the mutated segments with a wild-type one and restoring both superhelicity and motility.

J Mol Biol, 1991 Jul 5, 220(1), 67 - 77
A molecular switch: subunit rotations involved in the right-handed to left-handed transitions of Salmonella typhimurium flagellar filaments; Trachtenberg S et al.; Using the combined techniques of cryoelectron microscopy and image analysis, we generated three-dimensional reconstructions of flagellar filaments from straight, right-handed (SJW1655-R) and straight, left-handed (SJW1660-L) Salmonella typhimurium mutants, both of which have the same parental strain (SJW1103) . In the filaments from SJW1655, all flagellin subunits have the same conformation (R), while in filaments from SJW1660, the subunits are all in the alternate (L) conformation . The difference between the two three-dimensional density maps reveal the structural changes that accompany switching of the flagellin subunits between the two conformations . In going from the R to L state, the subunit undergoes a rotation 30 degrees clockwise about a radial axis and 38 degrees clockwise about a vertical axis, and suffers a 50 degrees bend of the outer, relative to the inner, subunit domain . The intersubunit spacing, along the 11-start protofilaments, changes from 51.6 A in the right-handed filament to 52.1 A in the left-handed filament . In order to produce the correct corkscrew shape in native filaments, the change in contacts that produces this shortening of 0.5 A must occur among the inner domains at a radius of about 30 A . We suggest that the changes in the middle domains of the subunit are the switch that forces changes in the inner domains.

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Last modified: May 25, 2005