Salmonella typhimurium

Mutat Res, 1988 Oct, 206(2), 193 - 200
Study on the mutagenicity of nifurtimox and eight derivatives with the L-arabinose resistance test of Salmonella typhimurium; Alejandre-Duran E et al.; The mutagenicity of nifurtimox (nfx) and 8 nfx analogues has been investigated with the L-arabinose forward-mutation assay of Salmonella typhimurium . The nfx analogues tested were obtained by replacing the 3-methyl-4-yl-tetrahydro-1,4-thiazine-1,1-dioxide group of the parent compound with the following other groups: indazol-1-yl (1); pyrazol-1-yl (2); benzimidazol-1-yl (3); 1,2,4-triazol-4-yl (4); 1-methyl-3-methylthio-1,2,4-triazol-4-yl-5-thione (5); 3,5-bis(methylthio)-1,2,4-triazol-4-yl (6); 1-adamantyl (7); 4,6-diphenylpyridin-1-yl-2-one (8) . The mutagenic activity of each chemical was determined by the standard plate-incorporation test, in the presence or absence of the S9 activation mixture . The 9 compounds were mutagenic and exhibited linear dose-mutagenic response relationships . They were direct-acting mutagens and showed a nearly 1000-fold range in mutagenic potency from chemical 1 to nfx . In most cases, the addition of S9 mixture to the test plates decreased the mutagenicity of compounds . This effect was particularly noticeable in the case of chemicals 1-3, 5 and 7 where a more than 70% decrease in mutagenic activity was observed in the presence of the S9 mixture . The mutagenic potency of compounds in the Ara test showed a negative linear correlation with previously reported antitrypanosomal activity . Thus, chemicals 6 and 8 with in vitro activities against Trypanosoma cruzi clearly superior to that of nfx showed 2 of the lowest mutagenic potencies in the Ara test and these were only somewhat higher than the mutagenicity of the reference drug.

Mutat Res, 1988 Oct, 206(2), 131 - 40
Mutagenic activities of selected nitrofluoranthene derivatives in Salmonella typhimurium strains TA98, TA98NR and TA98/1,8-DNP6; Zielinska B et al.; The mutagenic activities of novel nitrofluoranthene derivatives in Salmonella strains TA98, TA98NR and TA98/1,8-DNP6 (with and without S9 addition) are given . These derivatives were produced from the reactions of fluoranthene (FL) and its directly mutagenic 2- and 3-nitro derivatives with covalent dinitrogen pentoxide (N2O5) in CCl4 solution at ambient temperature . The influence of the addition of a nitro group on the observed activity of the resulting di- and tri-nitrofluoranthenes is discussed.

Pediatr Res, 1988 Oct, 24(4), 508 - 11
The effect of postnatal development on the adherence of nonfimbriated and fimbriated Salmonella typhimurium to isolated small intestinal enterocytes; el Monem AM et al.; The adherence of radiolabeled fimbriated (S 7471 OF) and nonfimbriated (S 7471 N) Salmonella typhimurium to small intestinal rat enterocytes was examined during postnatal development . The fimbriated strain invariably adhered in higher numbers than the nonfimbriated strain during all periods of development . The capability of enterocytes to bind Salmonella increased significantly during postnatal development and reached adult levels at weaning time (21 days of age) . Bacterial adherence to enterocytes was similar if the cells were isolated from the proximal or the distal small intestine . Early weaning of pups did not affect the capability of enterocytes to bind Salmonella . Pretreatment of isolated enterocytes from adult animals with rat's milk before exposure to Salmonella had no effect on the level of bacteria that adhered per enterocyte . Conversely, pretreatment of Salmonella with rats' milk before binding to enterocytes from adult animals also did not alter the level of bacteria adhered per enterocyte . These results suggest an age-dependent, postnatal development of available receptors for S . typhimurium on rat enterocytes . The acquisition of these receptors is not affected by mother's milk and is unaltered by early weaning.

Bioorg Khim, 1988 Oct, 14(10), 1419 - 27
{Incorporation of abequose residues into O-specific polysaccharides of Salmonella serotypes B, C2 and C3}; Druzhinina TN et al.; The possibility of chemical-enzymatic synthesis of O-specific polysaccharide and its modified derivatives was demonstrated with a cell envelope preparation from Salmonella typhimurium using synthetic polyprenyl pyrophosphate oligosaccharides and CDP-{14C}Abe . It was shown that during biosynthesis of O-specific polysaccharides from S . newport and S . kentucky abequosylation reaction occurs prior to polymerization of oligosaccharide repeating units.

J Mol Biol, 1988 Sep 20, 203(2), 353 - 72
Structure and organization of Marchantia polymorpha chloroplast genome . IV . Inverted repeat and small single copy regions; Kohchi T et al.; We characterized the genes in the regions of large inverted repeats (IRA and IRB, 10,058 base-pairs each) and a small single copy (SSC 19,813 bp) of chloroplast DNA from Marchantia polymorpha . The inverted repeat (IR) regions contain genes for four ribosomal RNAs (16 S, 23 S, 4.5 S and 5 S rRNAs) and five transfer RNAs (valine tRNA(GAC), isoleucine tRNA(GAU), alanine tRNA(UGC), arginine tRNA(ACG) and asparagine tRNA(GUU)) . The gene organization of the IR regions in the liverwort chloroplast genome is conserved, although the IR regions are smaller (10,058 base-pairs) than any reported in higher plant chloroplasts . The small single-copy region (19,813 base-pairs) encoded genes for 17 open reading frames, a leucine tRNA(UAG) and a proline tRNA(GGG)-like sequence . We identified 12 open reading frames by homology of their coding sequences to a 4Fe-4S-type ferredoxin protein, a bacterial nitrogenase reductase component (Fe-protein), five human mitochondrial components of NADH dehydrogenase (ND1, ND4, ND4L, ND5 and ND6), two Escherichia coli ribosomal proteins (S15 and L21), two putative proteins encoded in the kinetoplast maxicircle DNA of Leishmania tarentolae (LtORF 3 and LtORF 4), and a bacterial permease inner membrane component (encoded by malF in E . coli or hisQ in Salmonella typhimurium).

J Biol Chem, 1988 Sep 15, 263(26), 12986 - 93
Glucose permease of Escherichia coli . Purification of the IIGlc subunit and functional characterization of its oligomeric forms; Meins M et al.; The membrane subunit (IIGlc) of the glucose permease has been purified from overproducing Escherichia coli . About 2 mg of pure protein was obtained from 10 g (wet weight) of cells . IIGlc of E . coli and Salmonella typhimurium are functionally indistinguishable . A small difference was revealed, however, by a monoclonal antibody which neutralizes glucose phosphorylation activity of IIGlc from S . typhimurium, but does not cross-react with IIGlc of E . coli . A dimeric form of purified IIGlc can be detected by chemical cross-linking and by zonal sedimentation at 4 degrees C . Upon mild oxidation a disulfide bond is formed between the subunits of the dimer . Oxidized IIGlc is more stable than the reduced form but is inactive because it cannot be phosphorylated by the cytoplasmic subunit (IIIGlc) of the glucose permease . Cys-421 could be identified as the oxidation-sensitive residue, using a novel assay to detect IIIGlc-dependent phosphorylation of nitrocellulose-bound IIGlc that has been purified by gel electrophoresis . No dimeric form of phosphorylated IIGlc could be detected . Because phosphorylated IIGlc is a catalytic intermediate it is concluded that catalytically active IIGlc is a monomer and that the dimeric form is an artefact observed only with purified resting IIGlc . That IIGlc is active as a monomer is further supported by the observation that monomeric IIGlc catalyzes phosphoryl exchange between glucose and glucose 6-phosphate at equilibrium and that an excess of inactive IIGlc with a serine replacing Cys-421 does not interfere with the activity of wild-type IIGlc as would be expected if interaction between the subunits in a dimer were essential for activity.

Eur J Biochem, 1988 Sep 15, 176(2), 421 - 9
Nucleotide sequence of the carA gene and regulation of the carAB operon in Salmonella typhimurium; Kilstrup M et al.; The carAB operon of Salmonella typhimurium encoding carbamoyl-phosphate synthetase (CPSase) has been cloned, and the nucleotide sequence of the first gene of the operon, carA, together with 760 base pairs of the 5'-flanking region was determined . The product of the carA gene is the small subunit of CPSase . It catalyzes the transfer of the amide group from glutamine to an NH3-site on the heavy subunit . Primer extension and S1 nuclease mapping of in vivo carAB transcripts revealed that transcription is similar to that of Escherichia coli {Piette, J . et al . (1984) Proc . Natl Acad . Sci . USA 81, 4134-4138} in its initiation at two promoters, P1 and P2, controlled by pyrimidines and arginine, respectively . The arginine control is mediated through binding to the arginine repressor (argR) . The involvement of titratable regulatory elements is indicated by the escape from both arginine and pyrimidine control, when the operon is present in multicopies on a plasmid . Measurements of CPSase levels in mutants which allows independent manipulation of the intracellular uracil and cytosine nucleotide pools show, that both uracil and cytosine nucleotides are required for full repression and that limitation of either nucleotide results in derepression of CPSase synthesis . Deletion analyses indicate that regions upstream of the P1 promoter are required for normal expression from this promoter but not from P2.

Nucleic Acids Res, 1988 Sep 12, 16(17), 8207 - 11
Codon usage patterns in Escherichia coli, Bacillus subtilis, Saccharomyces cerevisiae, Schizosaccharomyces pombe, Drosophila melanogaster and Homo sapiens; a review of the considerable within-species diversity; Sharp PM et al.; The genetic code is degenerate, but alternative synonymous codons are generally not used with equal frequency . Since the pioneering work of Grantham's group it has been apparent that genes from one species often share similarities in codon frequency; under the "genome hypothesis" there is a species-specific pattern to codon usage . However, it has become clear that in most species there are also considerable differences among genes . Multivariate analyses have revealed that in each species so far examined there is a single major trend in codon usage among genes, usually from highly biased to more nearly even usage of synonymous codons . Thus, to represent the codon usage pattern of an organism it is not sufficient to sum over all genes as this conceals the underlying heterogeneity . Rather, it is necessary to describe the trend among genes seen in that species . We illustrate these trends for six species where codon usage has been examined in detail, by presenting the pooled codon usage for the 10% of genes at either end of the major trend . Closely-related organisms have similar patterns of codon usage, and so the six species in Table 1 are representative of wider groups . For example, with respect to codon usage, Salmonella typhimurium closely resembles E . coli, while all mammalian species so far examined (principally mouse, rat and cow) largely resemble humans.

Mutat Res, 1988 Sep, 201(1), 181 - 8
Mutagenic and carcinogenic heterocyclic amines in Chinese cooked foods; Zhang XM et al.; Samples of 7 foods commonly eaten in the Northeast of China (i.e . fried and broiled fishes and broiled meat) were tested for mutagenicity on Salmonella typhimurium TA98 with S9 mix . The basic fractions of the samples were mutagenic, inducing 33-2930 revertants/g of cooked food . Fried walleye pollack (a kind of cod fish heated on a stainless steel pan) showed the highest mutagenicity, so attempts were made to isolate mutagens from the basic fraction of this food . The mutagens were purified by treatment with blue cotton and HPLC on a semi-preparative ODS column and analytical cation exchange and ODS columns . 5 mutagens were isolated and identified as 2-amino-3-methylimidazo{4,5-f}quinoline (IQ), 2-amino-3,4-dimethylimidazo{4,5-f}quinoline (MeIQ), 2-amino-3,8-dimethylimidazo{4,5-f}quinoxaline (MeIQx), 2-amino-3,4,8-trimethylimidazo{4,5-f}quinoxaline (4,8-DiMeIQx) and 2-amino-1-methyl-6-phenylimidazo{4,5-b}pyridine (PhIP) . 1 g of fried fish was estimated to contain 0.16 ng of IQ, 0.03 ng of MeIQ, 6.44 ng of MeIQx, 0.10 ng of 4,8-DiMeIQx and 69.2 ng of PhIP . MeIQx and PhIP accounted for 24% and 4.7%, respectively, of the total mutagenicity . The other 3 heterocyclic amines were each responsible for only 0.3-1.2% of the total mutagenicity.

Food Chem Toxicol, 1988 Sep, 26(9), 791 - 6
N,N-diethylphenylacetamide, an insect repellent: absence of mutagenic response in the in vitro Ames test and in vivo mouse micronucleus test; Meshram GP et al.; N,N-diethylphenylacetamide (DEPA), a promising new insect repellent, was tested for mutagenicity in the in vitro Ames Salmonella/microsome mutagenicity test and the in vivo mouse micronucleus test . For the Ames test, DEPA was assayed both in the presence and absence of Aroclor 1254-induced rat-liver S-9 mix (5 and 20% S-9 fraction), using five tester strains of Salmonella typhimurium--TA97a, TA98, TA100, TA102 and TA104 . For the micronucleus test, mice were exposed to DEPA through ip injection for 2 and 5 days in separate experiments, and bone marrow and peripheral blood were sampled 6 and 48 hr after the final injection, respectively . DEPA did not induce a mutagenic response in the Ames test, and mouse bone marrow and peripheral blood micronucleus tests . DEPA was not considered cytotoxic, as a depression of the percentage PCE was not observed at any dose in the range of 1 to 100 mg/kg body weight with either treatment protocol of the micronucleus test.

Res Vet Sci, 1988 Sep, 45(2), 240 - 50
Pathology of calves with diarrhoea in southern Britain; Hall GA et al.; Twenty-one moribund calves with diarrhoea were purchased from 11 farms, their faeces examined for enteropathogens and samples of intestinal tissue removed under anaesthesia . Lesions and presence of enteropathogens on the mucosal surface were scored by histological examination of immunostained paraffin sections . Two or more enteropathogens were detected in 19 calves . Cryptosporidium appeared to be the principal cause of diarrhoea in six calves, rotavirus in four, Salmonella typhimurium in two, bacteria adherent to the surface of the large intestine in two, coronavirus in one and K99+ Escherichia coli in one calf . Diarrhoea in four calves was the consequence of mixed infections in which no one enteropathogen appeared to predominate . In one calf no enteropathogen was detected . Diarrhoea was associated with infections and lesions throughout the small and large intestines . The enteropathogens most frequently associated with lesions in the small intestines were rotavirus, coronavirus and cryptosporidium; in the large intestines they were coronavirus and bacteria apparently adherent to the mucosal surface.

Mutagenesis, 1988 Sep, 3(5), 381 - 7
Concentrated drinking water extracts, which cause bacterial mutation and chromosome damage in CHO cells, do not induce sex-linked recessive lethal mutations in Drosophila; Wilcox P et al.; Concentrated extracts prepared from chlorinated drinking water samples were tested for their ability to induce sex-linked recessive lethal mutations in Drosophila melanogaster . Adult flies were allowed to feed on sucrose solutions prepared using neat or half-strength water extract . The drinking water extracts used for this study were also tested in bacterial fluctuation assays using Salmonella typhimurium TA100 and TA98 and in an in vitro cytogenetic assay using CHO cells . Although the water extracts gave positive results in both of these in vitro tests, there was no evidence of mutagenic activity in the Drosophila studies.

Mol Gen Genet, 1988 Sep, 214(1), 32 - 6
Salmonella typhimurium LT2 metF operator mutations; Stauffer GV et al.; Using an Escherichia coli lac deletion strain lysogenized with lambda phage carrying a metF-lacZ gene fusion (lambda Flac), in which beta-galactosidase levels are dependent on metF gene expression, cis-acting mutations were isolated that affect regulation of the Salmonella typhimurium metF gene . The mutations were located in a region previously defined as the metF operator by its similarity to the E . coli metF operator sequence . Regulation of the metF gene was examined by measuring beta-galactosidase levels in E . coli strains lysogenized with the wild-type lambda Flac phage and mutant lambda Flac phage . The results suggest that the mutations disrupt the methionine control system mediated by the metJ gene product, but not the vitamin B12 control system mediated by the metH gene product . The results also demonstrate that negative control of the metF gene by the metH gene product and vitamin B12 is dependent on a functional metJ gene product.

Food Chem Toxicol, 1988 Sep, 26(9), 745 - 52
Reduction of mutagenicity and toxicity of aflatoxin B1 by chlorine gas treatment; Sen AC et al.; Chlorine gas was used to treat aflatoxin B1 (AFB1) . The time-related exposure study showed that 4 ml (15 mg) pure chlorine gas caused about 90% destruction of 100 micrograms AFB1 within 10 min, at standard temperature and pressure . Four fluorescent reaction products were produced, two of which were identified as 8,9-dichloro-AFB1 and 8,9-dihydroxy-AFB1 (diol) . The use of {14C}AFB1 confirmed the 90% destruction of the compound by chlorine gas . An increased destruction of AFB1 also occurred when an increased amount of chlorine gas was used . The mutagenic activity of the AFB1 sample treated for 10 min was reduced to about 5% of the untreated control using the Salmonella typhimurium strain TA98 in the presence of a rat-liver S-9 mix . A similar time-related reduction in AFB1 toxicity after chlorine treatment was also achieved using the chicken embryo toxicity assay.

Mutat Res, 1988 Sep, 201(1), 241 - 51
Base-change analysis of revertants of the hisD3052 allele in Salmonella typhimurium; Fuscoe JC et al.; This report is an investigation of the specific sequence changes in the DNA of Salmonella hisD3052 revertants induced by a set of specific frameshift mutagens found in our diet . They include B{a}P, aflatoxin B1, and the cooked-food mutagens, IQ, MeIQ, and PhIP . The Salmonella DNA was cleaved with restriction enzymes Sau3A, EcoR1, and Alu1 to give a 620-bp fragment containing the hisD3052 site . The size-fractionated fragments were ligated to the bacteriophage vector M13mp8 . After transformation into E . coli, the recombinants were screened with a nick-translated hisD+ gene probe, and the isolated single-stranded DNA was sequenced . All IQ (13), MeIQ (3), PhIP (5), and aflatoxin B1 (3) induced revertants isolated had a 2-base (-CG- dinucleotide) deletion situated 10 bases upstream from the original hisD3052 -C- deletion . In contrast, 9 of 24 revertants induced by B{a}P had extensive deletions varying from 8 to 26 nucleotides in length and located at various sites along a 45-base-pair sequence beginning at nucleotide 2085 of the his operon . The other 15 B{a}P-induced revertants had a -CG- deletion at the same location as the revertants induced by the other food mutagens . 7 spontaneous revertants were also analyzed; they showed 3 -CG- deletions, 1 insertion and 3 distinct deletions (varying from 2 to 11 bases in size) . In total, 13 distinct base changes are described which lead to reversion of the hisD3052 mutation.

Infect Immun, 1988 Sep, 56(9), 2324 - 9
Effect of small cationic leukocyte peptides (defensins) on the permeability barrier of the outer membrane; Viljanen P et al.; Defensins are small cationic antibacterial peptides that are abundant in polymorphonuclear leukocytes from human and other sources (T . Ganz, M . Selsted, D . Szklarek, S . Harwig, K . Daher, D . F . Bainton, and R . J . Lehrer, J . Clin . Invest . 76:1427-1435, 1985) . We studied whether subinhibitory concentrations of defensins increase the outer membrane (OM) permeability of Escherichia coli, Salmonella typhimurium, and Pseudomonas aeruginosa to hydrophobic probes, as do many other polycations that have been studied previously . Throughout the study, we used polymyxin B nonapeptide (PMBN) as a reference peptide . PMBN has a known potent OM permeability-increasing action . As a sharp contrast to PMBN, subinhibitory concentrations of defensins did not permeabilize (or, under some test conditions, permeabilized very slightly) the OM to the probes that were used (rifampin and Triton X-100) . At bacteriostatic or bactericidal defensin concentrations, some degree of synergism with rifampin was seen.

J Gen Microbiol, 1988 Sep, 134 ( Pt 9), 2535 - 41
Bacteriophage X-2: a filamentous phage lysing IncX-plasmid-harbouring bacterial strains; Coetzee JN et al.; Phage X-2, a filamentous rod about 950 nm in length, was isolated from sewage as plating on strains of Escherichia coli, Salmonella typhimurium or Serratia marcescens carrying either the IncX plasmid R6K, or the unique plasmid R775 . Phage X-2 differs morphologically from a previously described very broad host range filamentous phage X which also lyses plasmid R6K-carrying strains and the phages differ in their resistance to inactivation by diethyl ether . Phage X-2 is serologically unrelated to phage X and the X-like phages IKe and I2-2 . The adsorption site of the phage on the plasmid-bearing strains could not be determined but evidence implicating conjugative pili is presented.

Mutagenesis, 1988 Sep, 3(5), 423 - 7
Caffeine inhibits hepatic-microsomal activation of some dietary genotoxins; Alldrick AJ et al.; Hepatic microsomal fractions (microsomes) were prepared from female BALB/c mice . The potential of caffeine to modify the ability of microsomes to convert the heterocyclic aromatic amines MeIQ, Trp-P-2 and MeIQx, to bacterial mutagens (indicator: Salmonella typhimurium TA98) was investigated . Caffeine inhibited mutagenicity and did so by inhibiting microsomal metabolism of the three compounds, rather than by altering uptake of the active mutagens and/or interacting with the DNA repair processes in the bacterial cell . Notional Ki values determined for the three heterocyclic amines were similar, suggesting that caffeine inhibits at a stage common to the metabolism of all three compounds.

Br Poult Sci, 1988 Sep, 29(3), 521 - 9
Genetics of resistance to Salmonella typhimurium in newly hatched chicks; Bumstead N et al.; 1 . A survey of inbred and partially inbred lines of chickens showed pronounced differences in mortality following challenge of the newly hatched chicks with Salmonella typhimurium . Lines W, 6(1) and N were highly resistant to challenge, whereas lines C and 15I were highly susceptible . 2 . This difference in susceptibility was observed with a range of 5 strains of S . typhimurium of different degrees of virulence and also following both oral and intramuscular challenge . 3 . The inheritance of resistance was studied in detail by examining a series of crosses between the susceptible line C and resistant line W . The pattern of mortality in crosses and back-crosses between these lines indicated resistance is dominant and was consistent with the inheritance of a dominant autosomal resistance gene . 4 . There was no evidence of maternal effects in these crosses, and no evidence of association with the major histocompatability complex.

Zh Mikrobiol Epidemiol Immunobiol, 1988 Sep, (9), 28 - 33
{The role of the aggregation of microbial cells in the development of salmonellosis in mice}; Zhalko-Titarenko VP et al.; The dependence of the invasive action of Salmonella typhimurium in mice on the aggregation of microbial cells has been studied in vivo, as well as in vitro on explanted intestinal tissue . The aggregation of salmonellae on kaolin grains has been found to lead to an increase in the level of adhesion of salmonellae to the intestinal mucosa of mice in vitro, to the accelerated course of infection in mice and their death and to the increased contamination of the spleen . The data obtained in these experiments age indicative of the possibility of the adverse influence of some sorbents on the course of the infectious process and confirm the concept advanced by the authors on the major importance of the surface concentration of salmonellae on the mucous membrane for the effectiveness of contamination.

Sangyo Igaku, 1988 Sep, 30(5), 385 - 91
{Comparative study on the mutagenic activity of rat liver and bladder S9 by fluctuation test}; Hayashi K et al.; Mutagenicity of seven aromatic amines, two heterocyclic amines, two azo compounds and one polycyclic aromatic hydrocarbon was examined with a fluctuation test modified by Gatehouse . The test was performed by using Salmonella typhimurium TA98 in the presence of liver and bladder S9 from PCB pretreated rats . Seven out of 12 compounds showed mutagenic activities with liver S9 and seven with bladder S9 . Benzidine, 3-methylcholanthrene and 2-acetylaminofluorene showed a negative response with bladder S9 but a positive response with liver S9 . The mutagenicity of the seven compounds observed with bladder S9 had a lower sensitivity than with liver S9 . 3-Amino-1,4-dimethyl-5H-pyrido{4,3-b}indole and 3-amino-1-methyl-5H-pyrido{4,3-b}indole showed mutagenic activity at lower concentrations than the other compounds which showed mutagenic activity either with bladder S9 or liver S9 . Mutagenicity of 3-methylcholanthrene was observed at high concentration only in the presence of liver S9 . The findings from the present study suggested that aromatic amines, heterocyclic amines and polycyclic aromatic hydrocarbons were more likely to be activated to strong mutagens with liver S9 than with bladder S9.

J Nat Prod, 1988 Sep-Oct, 51(5), 866 - 73
Plant antimutagenic agents, 1 . General bioassay and isolation procedures; Wall ME et al.; An antimutagenic assay in Salmonella typhimurium has been utilized for a study of the inhibition of the mutagenic activity of 2-aminoanthracene in the presence of the Ames S-9 metabolic activation preparation by crude organic solvent extracts of plant materials . More than 2000 extracts representing 39 families have been tested to date . Confirmed inhibitory activity has been found in 80 samples . More than 60% were nontoxic . Methods for isolation and characterization of pure compounds are presented . Of particular interest is the utilization of large scale preparative hplc for rapid purification of inhibitory chromatographic fractions that were still highly impure.

Mol Biol Evol, 1988 Sep, 5(5), 531 - 48
Evolution of aminobenzoate synthases: nucleotide sequences of Salmonella typhimurium and Klebsiella aerogenes pabB; Goncharoff P et al.; p-Aminobenzoate synthase (PS) and anthranilate synthase (AS) are structurally related enzymes that catalyze similar reactions and produce similar products, para- and ortho-aminobenzoate (anthranilate) . Each enzyme is composed of two non-identical subunits: a glutamine amidotransferase subunit (CoII) and a subunit that produces an aminobenzoate product (CoI) . Nucleotide sequence comparisons of the Escherichia coli genes encoding each of the subunits suggest a common evolutionary origin for both subunits of the enzyme complexes . We report here the nucleotide sequences of the pabB genes that encode Salmonella typhimurium and Klebsiella aerogenes PS CoI . Comparative sequence information suggests that pabB is encoded as the first gene in a multicistronic transcript . Comparison of deduced amino acid sequences of PS CoI genes indicates that the majority of sequence identity occurs in the C-terminal two-thirds of the proteins . Similarly, identities in an alignment of eight PS and AS CoI sequences are confined to the C-terminal segments of the proteins . Secondary-structure predictions for the nine sequences suggest considerable similarity in the folding of the C-terminal portions of the aminobenzoate synthases.

Mutat Res, 1988 Sep-Oct, 209(1-2), 67 - 74
Relationships between structure of nitrated arenes and their mutagenicity in Salmonella typhimurium; 2- and 2,7-nitro substituted fluorene, phenanthrene and pyrene; Hirayama T et al.; In order to elucidate the mechanisms of mutagenic activation of nitroarenes, we studied the relationships between the mutagenic potency and chemical structure of 2-nitro- and 2,7-dinitro-arenes including nitrated fluorene (Fl), dihydrophenanthrene (DHPh), phenanthrene (Ph), tetrahydropyrene (THPy), dihydropyrene (DHPy) and pyrene (Py) together with 9-NO2-Ph, 1-NO2-Py and 1.3-diNO2-Py . The mutagenicity tests were carried out on Salmonella typhimurium TA98, TA98NR and TA98/1,8-DNP6 in the absence of S9 mix . The order of mutability of mononitro- and dinitro-arenes in TA98 is as given below: 2-NO2-THPy less than 2-NO2-Fl less than 2-NO2-DHPh less than 9-NO2-Ph less than 2-NO2-Ph less than 2-NO2-DHPy less than 1-NO2-Py less than 2-NO2-Py, and 2,7-diNO2-DHPh less than 2,7-diNO2-Fl less than 2,7-diNO2-THPy less than 2,7-diNO2-Ph less than 2,7-diNO2-DHPy less than 2,7-diNO2-Py less than 1,3-diNO2-Py . 9-NO2-Ph and 1-NO2-Py, which have been detected in environmental samples, are not as potent mutagens as 2-nitrated phenanthrene and pyrene, respectively . 2-NO2THPy (37.7 rev/nmole) was a weak mutagen, but 2,7-diNO2-THPy (3197 rev/nmole) was as potent a mutagen as 2,7-diNO2 (3925 rev/nmole) . Tetrahydropyrene has a twisted form in its structure . 1,3-diNO2-Py (99660 rev/nmole) was more mutagenic than 2,7-diNO2-Py (37960.0 rev/nmole), and their mutagenicities were correlated with the behavior of the K-band in their UV spectra by the introduction of nitro groups on pyrene.

Mutat Res, 1988 Sep, 201(1), 89 - 96
Study of the causes of direct-acting mutagenicity in coffee and tea using the Ara test in Salmonella typhimurium; Ariza RR et al.; The mutagenic activities of 6 of the chemicals identified in coffee solutions were assayed with the Salmonella Ara test, under experimental conditions optimized for coffee mutagenicity . Caffeine was the only non-mutagenic compound . Among the other 5 chemicals, hydrogen peroxide was the strongest mutagen and chlorogenic acid the weakest; methylglyoxal, glyoxal and caffeic acid exhibited intermediate mutagenicities . The minimal mutagenic doses of these components correlated negatively with their relative concentrations in coffee . It was concluded that chlorogenic acid, caffeic acid, glyoxal and methylglyoxal cannot contribute alone to the mutagenicity of coffee in the Ara test, since their minimal mutagenic concentrations were much higher than their respective levels in the coffee samples assayed . By contrast, 40-60% of the mutagenic activity in coffee and also in tea could be attributed to their H2O2 contents . Catalase abolished more than 95% of the mutagenic activity of coffee, as detected by the Ara test . A similar sensitivity to catalase has been reported by other authors in relation to the coffee mutagenicity identified by the Salmonella His test . Nevertheless, the results presented in this paper suggest that the Ara forward and the His reverse mutation tests are sensitive to the mutagenicity of different constituents in coffee solutions . We propose that the His test, sensitive at high coffee doses, mainly recognizes the mutagenicity of methylglyoxal, whilst the Ara test, sensitive at low coffee doses, mainly detects the mutagenic activity of hydrogen peroxide . The data reported also suggest that the direct-acting mutagenicity(ies) detected by the Ara test in tea solutions is (are) based on similar, if not identical, mechanisms.

Mutat Res, 1988 Sep, 201(1), 189 - 94
Phenotypic and reversion analysis of a Salmonella typhimurium constructed to have an arginine codon at the hisG46 missense codon; Miller JK et al.; Of the 6 single-base mutations that would be predicted to change the missense mutation hisG46 away from a proline codon in the Salmonella/microsome mutagen selection assay for histidine-independent revertants, only 5 have been observed . We have used site-specific mutagenesis to make the unobserved mutant {CCC (proline)----CGC (arginine)} codon in the Salmonella genome . Experiments with this arginine mutant demonstrate that, like bacteria containing the hisG46 mutation, bacteria with the arginine missense mutation are histidine auxotrophs which are capable of reversion to histidine independence . However, unlike the ATP phosphoribosyltransferase coded by the hisG46 his G gene (with a proline), the arginine mutant enzyme is partially active . This is indicated by a histidine-independent phenotype when the arginine hisG gene is present in multiple copies.

Mutat Res, 1988 Sep, 201(1), 127 - 36
Pure exogenous singlet oxygen: nonmutagenicity in bacteria; Dahl TA et al.; Singlet oxygen (1 delta gO2) is the lowest energy-excited state of molecular oxygen, and more reactive than the triplet ground-state molecule . Although singlet oxygen has been implicated in a variety of biological effects, including reactions with DNA or some of its components, evidence for mutagenesis by singlet oxygen has remained unclear . We have previously described a system for bacterial exposure to pure exogenous singlet oxygen that eliminates ambiguity regarding the identity of the reactive species responsible for observed results . Despite the potent toxicity of pure singlet oxygen for several different strains of bacteria, we have found no evidence for mutagenicity of singlet oxygen in 26 Salmonella typhimurium histidine-auxotrophic strains killed to 35% survival . These strains included a variety of base-pair substitution or frameshift target sequences for reversion, including targets responsive to oxidative damage and targets rich in GC base pairs . Some strains combined histidine mutations with one or more mutations affecting DNA-repair capacity . 4 strains possessing the hisG46 mutation also were not mutated when exposed to dose ranges killing less than 28% and up to 99% of the bacteria . The relative frequency of small inphase deletions was assayed in hisG428 bacteria exposed to single oxygen and found to be the same as the spontaneous level . In addition to lack of induction of mutation in these strains, the 8-azaguanine forward mutation assay yielded no evidence of mutagenesis by singlet oxygen in strains killed to 15% survival . No induction of genetic changes by singlet oxygen was seen in an assay for duplication of approximately 1/3 of the bacterial chromosome . Tests for the ability of singlet oxygen to induce lambda prophage in E . coli K12 also proved negative . These studies collectively indicate that pure singlet oxygen generated outside the bacterial cell does not react significantly with the bacterial chromosome in ways leading to base-pair substitutions, frameshift mutations, small or large deletions, large duplications, or damage that interferes with DNA replication and induces the SOS system.

Mutat Res, 1988 Sep, 201(1), 117 - 26
N-nitroso-N-2-fluorenylacetamide: a new direct-acting mutagen and teratogen; Lin JK et al.; Reaction of N-2-fluorenylacetamide (2-FAA, CAS No . 53-96-3) with nitrous fume (N2O3) in glacial acetic acid at 0 degree C yields N-nitroso-N-2-fluorenylacetamide (N-NO-2-FAA), 3-nitro-N-2-fluorenylacetamide, N-nitroso-3-nitro-N-2-fluorenylacetamide and other compounds . N-NO-2-FAA is the major product (80%) and fairly stable at low temperature (-20 degrees C), but extremely labile at ambient temperature . The chemical structure of N-NO-2-FAA is characterized by spectrometric analysis of its naphthol coupling derivatives . This new compound is highly mutagenic to Salmonella typhimurium TA97, TA98, TA100 and TA1538 and requires no microsomal metabolic activation . The mutagenicity of N-NO-2-FAA in TA98 is higher than that of N-methyl-N'-nitro-N-nitrosoguanidine (MNNG, CAS No . 70-25-7) and N-acetoxy-N-2-fluorenylacetamide (N-AcO-2-FAA) . The teratogenic potential of N-NO-2-FAA was studied with white Leghorn chick embryos given a single dose of 1-100 micrograms/egg on day 6 of incubation . A high incidence of flaccid paralysis of the legs and a low incidence of feather, claw and bill malformations were found in the treated group; no such malformed embryos were found in the control group . The teratogenicity of N-NO-2-FAA was found to be weaker than that of MNNG, but comparable to that of N-methyl-N-nitrosourea (CAS No . 684-93-5) . N-NO-2-FAA is a strong electrophile and reacts readily with histidine, lysine, cysteine, glutathione, tryptophan, adenosine, cytidine at neutral pH . In contrast to N-AcO-2-FAA, N-NO-2-FAA does not react significantly with guanosine and thymidine . It seems that N-NO-2-FAA is a strong direct-acting mutagen and probably a new prototype of synthetic carcinogen.

Mutat Res, 1988 Sep, 206(1), 65 - 71
Mutagen formed from tryptophan reacted with sodium nitrite in acidic solution; Ohara A et al.; The reaction products from L-tryptophan treated with nitrite under acidic conditions were investigated for mutagenic activity with the Salmonella typhimurium his reversion assay and for DNA-damaging activity using the rec-assay . The diethyl ether extract of the reaction mixture showed 8 spots on thin-layer chromatography (TLC) . One compound from the TLC had high mutagenic activity for TA98 without S9 mix, with little DNA-damaging activity . The mutagen was purified and identified by instrumental analysis as 2-hydroxy-(1-N-nitrosoindole)propionic acid (NIHP) . The mutagenic activity of NIHP was determined by the induced mutation frequency method; the induced mutation frequency was about 19.2 X 10(-5) at a dose level of 160 micrograms/plate.

Mutat Res, 1988 Sep, 206(1), 55 - 63
Induction of chromosomal aberrations in rat bone marrow cells and mutations in Salmonella typhimurium by benz{a}anthracene derivatives; Ito Y et al.; Benz{a}anthracene (BA) and its derivatives containing methyl and/or ethyl groups in the 7 and/or 12 positions were tested for their ability to induce chromosome aberrations (CA) in rat bone marrow cells and for their mutagenicity to Salmonella typhimurium TA100 or TA98 . The incidence of aberrant cells induced by the BA derivatives, given in lipid emulsion as a single-pulse dose of 50 mg/kg body weight into the caudal vein, was in the order: DMBA greater than EMBA greater than MEBA greater than other BA derivatives = control . The alkyl groups, at least 1 methyl group, at the 7 and 12 positions of BA seemed to be necessary to induce CA, although DEBA having ethyl groups at both the 7 and 12 positions of BA did not induce CA . DMBA or EMBA induced not only gaps and breaks but also exchanges and multiple CA, while the CA induced by other BA derivatives consisted of only gaps and breaks . 7MBA and 12MBA which exhibit carcinogenic activity intermediate between that of DMBA and BA induced few CA in the present system . However, the correlation coefficient between the logarithm incidence of aberrant cells and the carcinogenicity index calculated from the data of 9 BA derivatives including both 7MBA and 12MBA was 0.792 . The relative mutagenicities of the BA derivatives with TA100 in the presence of hepatic S9 from polychlorinated biphenyl (PCB)-treated rats were in the order: BA greater than 7MBA greater than DMBA greater than 12MBA greater than 7EBA greater than EMBA greater than MEBA greater than 12EBA = DEBA = control . The results with TA98 were essentially the same as those with TA100 . The results with TA100 in the presence of hepatic S9 from phenobarbital (PB)-treated rats were in the order: DMBA greater than 12MBA greater than 7MBA greater than 7EBA greater than BA greater than EMBA = MEBA greater than 12EBA = DEBA = control . These findings reveal no obvious relation between the mutagenic activities of the BA derivatives with the PCB-S9 or PB-S9 activating systems and their capacities to induce CA or their reported carcinogenicities . The incidence of CA induced by the dihydrodiols implicated as the metabolic precursors of the active diol epoxide metabolites of several of these BA derivatives was also tested . BA 3,4-dihydrodiol, like BA itself, induced few CA . However, the corresponding dihydrodiols of DMBA, 12MBA and 7MBA, induced relatively high levels of CA.(ABSTRACT TRUNCATED AT 400 WORDS)

Mutat Res, 1988 Sep, 206(1), 41 - 6
Genetic toxicology evaluation of commercial beers . II . Mutagenic activity of commercial beer products in Salmonella typhimurium strains TA98, TA100 and TA102; Brusick DJ et al.; 5 concentrated extracts of commercial beers were prepared using XAD-2 resin . The residues were subjected to evaluation for mutagenic activity in Salmonella typhimurium strains TA98, TA100 and TA102 . The tests were conducted using preincubation protocols including provisions for S9 metabolic activation . Although the extracts did produce moderate toxicity to the Salmonella organisms used in the assays, none of the residues were found to induce mutation up to their maximum testable concentrations.

Mutat Res, 1988 Sep, 206(1), 115 - 25
Mutagenicity of aromatic glycidyl ethers with Salmonella; Rosman LB et al.; 6 aromatic glycidyl ethers containing naphthyl, biphenyl or benzylphenyl substituents were synthesized . These epoxides together with the commercially available compounds 2-biphenylyl glycidyl ether were examined for dose-mutagenicity relationships using the plate incorporation Ames test with Salmonella typhimurium strains TA100 and TA1535 . Structure-mutagenicity relationships were further examined for these compounds and 3 phenyl glycidyl ethers by concurrent testing at a single dose with strain TA100 . Meaningful correlations could not be established for the mutagenicity of these epoxides to their molecular volumes, partition values, nor to their reactivities with the model nucleophile, 4-(4-nitrobenzyl) pyridine . However, it was noted that increased conjugated aromatic unsaturation with its resulting planarity led to increased mutagenicity and that this effect decreased when it was further removed from the epoxide moiety.

J Bacteriol, 1988 Sep, 170(9), 3855 - 63
Ethanolamine utilization in Salmonella typhimurium; Roof DM et al.; Ethanolamine can serve as the sole source of carbon and nitrogen for Salmonella typhimurium if vitamin B12 is present to serve as a cofactor . The pathway for ethanolamine utilization has been investigated in order to understand its regulation and determine whether the pathway is important to the selective forces that have maintained the ability to synthesize B12 in S . typhimurium . We isolated mutants that are defective in ethanolamine utilization (eut mutants) . These mutants defined a cluster of genes located between purC and cysA at 50 min on the Salmonella chromosome . A genetic map of the eut region was constructed . Included in the map are mutations which affect ethanolamine ammonia lyase, the first degradative enzyme, and mutations which affect the second enzyme in the pathway, acetaldehyde dehydrogenase . Transcriptional regulation of the eut genes was studied by using eut-lac operon fusions created by insertion of Mu d lac . Transcription is induced by the simultaneous presence of ethanolamine and B12 in the growth medium . The eut genes constitute a single unit of transcription . One class of mutations located at the promoter-distal end of the eut operon prevent induction of transcription.

Infect Immun, 1988 Sep, 56(9), 2407 - 11
Role of H-2 and non-H-2 genes in control of bacterial clearance from the spleen in Salmonella typhimurium-infected mice; Nauciel C et al.; The ability of mice to clear Salmonella typhimurium from their spleens in the late phase of infection was studied after inoculation with a temperature-sensitive mutant . Clearance of bacteria was delayed in C57BL/6 mice compared with BALB/c, C3H/HeJ, DBA/2, A/J, and CBA mice . The responses of F1 hybrids, backcrosses, and recombinant inbred strains derived from C57BL/6 and BALB/c (both Itys) and of H-2 congenic mice were analyzed . The results showed that the low rate of bacterial clearance was recessive, that the rate of clearance was under polygenic control, and that an H-2-linked gene(s) plays a major role . Among H-2 congenic mice with a C57BL/10 background, three phenotypes of bacterial clearance could be distinguished: high (H-2j, H-2q, and H-2u), intermediate (H-2d, H-2f, H-2k, H-2p, H-2r, H-2s, and H-2v), and low (H-2b) rates . The effect of the H-2 complex was apparent with different genetic backgrounds (Itys and Ityr) . In recombinant inbred strains derived from C57BL/6 (Itys) and A/J (Ityr) mice, the effect of the H-2b haplotype on bacterial clearance appeared to be fully expressed only in strains carrying the Itys allele.

Infect Immun, 1988 Sep, 56(9), 2209 - 17
Roles of motility, chemotaxis, and penetration through and growth in intestinal mucus in the ability of an avirulent strain of Salmonella typhimurium to colonize the large intestine of streptomycin-treated mice; McCormick BA et al.; Previously, it had been shown that an avirulent strain of Salmonella typhimurium, SL5316, with wild-type lipopolysaccharide (LPS) was a far better colonizer of the streptomycin-treated CD-1 mouse large intestine, was far more motile, did not bind to mouse intestinal mucus nearly as well as, but penetrated through a layer of intestinal mucus in vitro far better than an almost isogenic LPS-deficient transductant, SL5325 . In the present investigation, a nonflagellated transductant, SL5681, and a nonchemotactic transductant, SL5784, were isolated from SL5316 and tested for relative colonizing ability versus SL5316 (smooth) and SL5325 (rough) in streptomycin-treated mice . In addition, the Salmonella strains were tested for their ability to grow together in cecal intestinal mucus and in cecal luminal contents, for their tumbling and swimming activities after growth in cecal mucus, and for their ability to adhere to and travel through cecal mucus in vitro . The data show that the nonflagellated and nonchemotactic derivatives colonized large intestine nearly as well as their parent and were far better colonizers than the LPS-deficient mutant, that all the strains grew equally well in cecal mucus but did not grow in cecal luminal contents, and that cecal mucus-grown strains lost tumbling and swimming activities . Furthermore, the LPS-deficient strain adhered to cecal mucus far better but penetrated mucus far worse than did the nonflagellated transductant, the nonchemotactic transductant, and the parent . Thus, motility and chemotaxis do not appear to play a major role in the ability of the avirulent S . typhimurium strains to colonize the mouse large intestine, colonization may require growth in cecal mucus but does not depend on growth in cecal luminal contents, growth in cecal mucus inhibits S . typhimurium motility, and increased adhesion of the LPS-deficient mutant to cecal mucus and its poor ability to penetrate cecal mucus may play a role in its poor intestine-colonizing ability.

Mutat Res, 1988 Sep, 206(1), 83 - 90
Mutagenicity of amino acid and glutathione S-conjugates in the Ames test; Vamvakas S et al.; The mutagenicity of the glutathione S-conjugate S-(1,2-dichlorovinyl)glutathione (DCVG), the cysteine conjugates S-(1,2-dichlorovinyl)-L-cysteine (DCVC) and S-(1,2-dichlorovinyl)-DL-alpha-methylcysteine (DCVMC), and the homocysteine conjugates S-(1,2-dichlorovinyl)-L-homocysteine (DCVHC) and S-(1,2-dichlorovinyl)-DL-alpha-methylhomocysteine (DCVMHC) was investigated in Salmonella typhimurium strain TA2638 with the preincubation assay . DCVC was a strong, direct-acting mutagen; the cysteine conjugate beta-lyase inhibitor aminooxyacetic acid decreased significantly the number of revertants induced by DCVC; rat renal mitochondria (11,000 X g pellet) and cytosol (105,000 X g supernatant) with high beta-lyase activity increased DCVC mutagenicity at high DCVC concentrations . DCVG was also mutagenic without the addition of mammalian activating enzymes; the presence of low gamma-glutamyltransferase activity in bacteria, the reduction of DCVG mutagenicity by aminooxyacetic acid, and the potentiation of DCVG mutagenicity by rat kidney mitochondria and microsomes (105,000 X g pellet) with high gamma-glutamyltransferase activity indicate that gamma-glutamyltransferase and beta-lyase participate in the metabolism of DCVG to mutagenic intermediates . The homocysteine conjugate DCVHC was only weakly mutagenic in the presence of rat renal cytosol, which exhibits considerable gamma-lyase activity, this mutagenic effect was also inhibited by aminooxyacetic acid . The conjugates DCVMC and DCVMHC, which are not metabolized to reactive intermediates, were not mutagenic at concentrations up to 1 mumole/plate . The results demonstrate that gamma-glutamyltransferase and beta-lyase are the key enzymes in the biotransformation of cysteine and glutathione conjugates to reactive intermediates that interact with DNA and thereby cause mutagenicity.

Mol Gen Genet, 1988 Sep, 214(1), 11 - 5
Operon structure of flagellar genes in Salmonella typhimurium; Kutsukake K et al.; In Salmonella typhimurium, more than 40 genes have been shown to be involved in flagellar formation and function and almost all of them have been assigned to three regions of the chromosome, termed region I, region II, and region III . In the present study, a large number of transposon-insertion mutants in these flagellar genes were isolated using Tn10 and Mud1 . The flaV gene was found to be a strong hot spot for Tn10 insertion . Complementation analysis of the polarity effects exerted by the transposon-insertion mutants defined 13 different flagellar operons; 3 in region I, 4 in region II, and 6 in region III . These results are compared with the reported arrangement of the corresponding genes in Escherichia coli.

Mutat Res, 1988 Sep, 201(1), 169 - 80
Mechanisms of mutagenicity and toxicity of sodium selenite (Na2SeO3) in Salmonella typhimurium; Kramer GF et al.; The mechanisms of selenite toxicity and mutagenicity in S . typhimurium have been characterized . In contrast to previous reports, selenite toxicity was shown not to involve nonspecific incorporation into protein via the sulfur metabolic pathways . Selenite toxicity was, however, shown to involve its ability to act as an oxidizing agent, primarily through reactions with sulfhydryls . Strains which lack glutathione (GSH) are more sensitive to killing by sulfhydryl reagents . The selenite sensitivity of such a mutant was a biphasic phenomenon . The mutant was much more sensitive than a strain which contained GSH at lower selenite concentrations whereas, at higher concentrations, the mutant was much more resistant to selenite . The mechanism of selenite toxicity at lower concentrations in this mutant thus appeared to involve damage to intracellular sulfhydryls . The sensitization to higher doses of selenite by GSH could be explained by the generation of toxic oxygen species . The in vitro reactions of selenite with both cysteine and GSH readily produced H2O2 and O2- . A S . typhimurium strain which overproduces superoxide dismutase (SOD) and catalase was more resistant to high concentrations of selenite, but not killing by the lower doses . Pretreatment of cells with a nonlethal dose of selenite induced the synthesis of proteins which protected the cells from killing by H2O2 or high doses of selenite . Selenite was also a mutagen in the tester strain TA104, in which a number of other oxidizing agents have also been found to be mutagens . These results were consistent with a model in which the reactions of selenite and intracellular thiols with concomitant production of active oxygen species are the primary causal agents of selenite mutagenicity and toxicity in S . typhimurium.

Mutat Res, 1988 Sep, 194(2), 131 - 41
A mutation in the DNA adenine methylase gene (dam) of Salmonella typhimurium decreases susceptibility to 9-aminoacridine-induced frameshift mutagenesis; Ritchie L et al.; A mutant of Salmonella typhimurium with a reduced response to mutation induction by 9-aminoacridine (9AA) has been isolated . The mutation (dam-2) is located in the DNA adenine methylase gene . The dam-2 mutant strain exhibits a level of sensitivity to 2-aminopurine (2AP) intermediate between that of the dam+ and the DNA adenine methylation-deficit dam-1 strain, and 2AP sensitivity was reversed by introduction of a mutH mutation or of the plasmid pMQ148 (which carries a functional Escherichia coli dam+ gene) . However, the dam-2 strain is not grossly defective in DNA adenine methylase activity . Whole cell DNA appears full methylated at -GATC- sites . The levels of 9AA required to induce equivalent levels of frameshift mutagenesis in the dam-2 strain were approximately 2-fold higher than for the dam+ strain . Introduction of pMQ148 dam+ reduced the level of 9AA required for induction of frameshift mutations 4-fold in the dam-2 strain and 2-fold in the dam+ strain . The dam-2 mutation had no effect on the levels of ICR191 required for induction of frameshift mutations, but introduction of pMQ148 reduced the ICR191-induced mutagenesis 2-fold . The dam+/pMQ148, dam-2/pMQ148 and dam-1/pMQ148 strains showed identical dose-response curves for both 9AA and ICR191 . These results are consistent with a slightly reduced (dam-2) or increased (pMQ148) rate of methylation at the replication fork . The 2AP sensitivity of the dam-2 strain cannot be simply explained . Furthermore, addition of methionine to the assay medium reverses the 2AP sensitivity of the dam-2 strain, but has no effect on 9AA mutagenesis.

J Bacteriol, 1988 Sep, 170(9), 4304 - 8
Genetic evidence for modulation of the activator by two regulatory proteins involved in the exogenous induction of phosphoglycerate transport in Salmonella typhimurium; Jiang SQ et al.; Previous work from this laboratory has identified in a fragment of DNA, cloned from Salmonella typhimurium, two genes involved in the exogenous induction of phosphoglycerate transport . These two genes, the transporter gene, pgtP, and the activator gene, pgtA, are closely linked physically; they are only 3.4 kilobases apart . In the accompanying paper, we describe the determination of the nucleotide sequence of this 3.4-kilobase DNA segment and show that this segment contains two genes, pgtB and pgtC, encoding two polypeptides of 593 and 397 amino acid residues, respectively . This paper presents an analysis of the effects of insertions and deletions in pgtBC on the expression of pgtP gene and on the expression of lacZ fused to the pgtP gene . The results indicate that both pgtBC genes are necessary for expression of the pgtP gene . Strikingly, deletion of both genes resulted in a constitutive phenotype, suggesting that PgtB and PgtC polypeptides modulate PgtA activity . The expression of the pgtP gene appears to be regulated by the pgtA gene product, which acts as an activator . A model of induction is proposed in which the central feature is the interaction of the three regulatory proteins in the membrane such that the activity of the activator (PgtA) is subject to modulation by the binding of an inducer.

J Bacteriol, 1988 Sep, 170(9), 4299 - 303
Identification of the products and nucleotide sequences of two regulatory genes involved in the exogenous induction of phosphoglycerate transport in Salmonella typhimurium; Yang YL et al.; We describe the determination of the nucleotide sequence of two genes (pgtB and pgtC) contained within the 3.4-kilobase DNA segment sandwiched between the transporter gene, pgtP, and the regulatory gene, pgtA . These two genes are involved in the regulation of expression of phosphoglycerate transport in Salmonella typhimurium . The sequence indicates the presence of two large open reading frames, potentially coding for two polypeptides of 397 and 593 amino acid residues . The two gene products were identified by using the bacteriophage T7 RNA polymerase-T7 promoter coupled system of Tabor and Richardson, and the observed apparent mass of 45 and 69 kilodaltons correlated well with the respective open reading frames . The cellular location of these two polypeptides was directly determined, and the polypeptides were found to be associated with the membrane . Although overall these polypeptides appear to be hydrophilic, there is one hydrophobic transmembrane segment in the smaller polypeptide and four such segments in the larger polypeptide which can account for their association with the membrane . In the accompanying paper, we present genetic evidence that pgtB and pgtC genes are involved in the induction of the pgtP expression by modulating derepressor activity.

J Bacteriol, 1988 Sep, 170(9), 4119 - 24
Organization and temporal expression of a flagellar basal body gene in Caulobacter crescentus; Hahnenberger KM et al.; Caulobacter crescentus assembles a single polar flagellum at a defined time in the cell cycle . The protein components of the flagellar hook and filament are synthesized just prior to their assembly . We demonstrated that the expression of a gene, flaD, that is involved in the formation of the flagellar basal body is under temporal control and is transcribed relatively early in the cell cycle, before the hook and flagellin genes are transcribed . Thus, the order of flagellar gene transcription reflects the order of assembly of the protein components . A mutation in the flaD gene results in the assembly of a partial basal body which is missing the outermost P and L rings as well as the external hook and filament (K.M . Hahnenberger and L . Shapiro, J . Mol . Biol . 194:91-103, 1987) . The flaD gene was cloned and characterized by nucleotide sequencing and S1 nuclease protection assays . In contrast to the protein components of the hook and filament, the protein encoded by the flaD gene contains a hydrophobic leader peptide . The predicted amino acid sequence of the leader peptide of flaD is very similar to the leader peptide of the flagellar basal body P ring of Salmonella typhimurium (M . Homma, Y . Komeda, T . Iino, and R.M . Macnab, J . Bacteriol . 169:1493-1498, 1987).

J Bacteriol, 1988 Sep, 170(9), 3991 - 5
Construction of delta aroA his delta pur strains of Salmonella typhi; Edwards MF et al.; Salmonella typhi strains with two deletion mutations, each causing an attenuating auxotrophy, have been constructed from strains Ty2 and CDC 10-80 for possible use as oral-route live vaccines . An aroA(serC)::Tn10 transposon insertion was first transduced from a Salmonella typhimurium donor into each wild-type S . typhi strain . Transductants of the Aro- SerC- phenotype were treated with transducing phage grown on an S . typhimurium strain with an extensive deletion at aroA; selection for SerC+ yielded transductants, some of which were delta aroA . A his mutation was next inserted into a delta aroA strain in each line by two steps of transduction . Two deletions affecting de novo purine biosynthesis were used as second attenuating mutations: delta purHD343, causing a requirement for hypoxanthine (or any other purine) and thiamine, and delta purA155, causing an adenine requirement . The purHD343 deletion was introduced into the delta aroA his derivatives of each strain by cotransduction with purH::Tn10, and the purA155 deletion was introduced into the CDC 10-80 delta aroA his derivative by cotransduction with an adjacent silent Tn10 insertion by selection for tetracycline resistance . Tetracycline-sensitive mutants of each of the three delta aroA his delta pur strains were isolated by selection for resistance to fusaric acid . The tetracycline-sensitive derivative of the CDC 10-80 delta aroA his delta purA155 strain, designated 541Ty, and its Vi-negative mutant, 543Ty, constitute the candidate oral-route live-vaccine strains used in a recent volunteer trail (M . M . Levine, D . Herrington, J . R . Murphy, J . G . Morris, G . Losonsky, B . Tall, A . A . Lindberg, S . Stevenson, S . Baqar, M . F . Edwards, and B . A . D . Stocker, J . Clin . Invest . 79:885-902, 1987) . Tetracycline-sensitive mutants of the delta aroA his delta purHD derivative of strains Ty2 and CDC 10-80 may also be appropriate as live vaccines but have not been tested as such.

J Bacteriol, 1988 Sep, 170(9), 3903 - 9
Differential regulation by cyclic AMP of starvation protein synthesis in Escherichia coli; Schultz JE et al.; Of the 30 carbon starvation proteins whose induction has been previously shown to be important for starvation survival of Escherichia coli, two-thirds were not induced in cya or crp deletion mutants of E . coli at the onset of carbon starvation . The rest were induced, although not necessarily with the same temporal pattern as exhibited in the wild type . The starvation proteins that were homologous to previously identified heat shock proteins belonged to the latter class and were hyperinduced in delta cya or delta crp mutants during starvation . Most of the cyclic AMP-dependent proteins were synthesized in the delta cya mutant if exogenous cyclic AMP was added at the onset of starvation . Furthermore, beta-galactosidase induction of several carbon starvation response gene fusions occurred only in a cya+ genetic background . Thus, two-thirds of the carbon starvation proteins of E . coli require cyclic AMP and its receptor protein for induction; the rest do not . The former class evidently has no role in starvation survival, since delta cya or delta crp mutants of either E . coli or Salmonella typhimurium survived starvation as well as their wild-type parents did . The latter class, therefore, is likely to have a direct role in starvation survival . This possibility is strengthened by the finding that nearly all of the cya- and crp-independent proteins were also induced during nitrogen starvation and, as shown previously, during phosphate starvation . Proteins whose synthesis is independent of cya- and crp control are referred to as Pex (postexponential).

Carcinogenesis, 1988 Sep, 9(9), 1523 - 7
Fusarium moniliforme metabolites: genotoxicity of culture extracts; Lu SJ et al.; Fusarin C (FC) is a potent mutagen which has been isolated from Fusarium moniliforme culture extracts (FME) . We have confirmed that the mutagenicity of these extracts is enhanced by phenobarbital- or Aroclor-induced microsomes and shown that: (i) additional, direct-acting, mutagens are present in crude extracts from F . moniliforme cultures; (ii) Salmonella typhimurium TA 100 exposed to FME in the presence of S9 mixtures shows an increased number of DNA strand breaks as detected by intercalation of ethidium bromide; (iii) exposure of polyoma-transformed rat fibroblast cells to HPLC-purified FC induced asynchronous replication of polyoma DNA sequences, a phenomenon also observed when these cells were exposed to a variety of other carcinogens; (iv) FME can alkylate 4-(p-nitrobenzyl)pyridine in the absence of S9 mix, although less efficiently than styrene oxide; and (v) these additional direct-acting mutagens, present in crude extracts from F . moniliforme cultures, may be responsible for the DNA adducts formed by reaction with calf thymus DNA in the absence of metabolic activation and detected by the 32P-postlabeling assay . All of these observations suggest that significant health effects may be associated with human exposure to F . moniliforme and that further studies on its metabolites are needed.

J Mol Biol, 1988 Aug 20, 202(4), 787 - 808
Three-dimensional reconstruction of the flagellar filament of Caulobacter crescentus . A flagellin lacking the outer domain and its amino acid sequence lacking an internal segment; Trachtenberg S et al.; We obtained a three-dimensional reconstruction of the flagellar filament of Caulobacter crescentus CB15 from electron micrographs of negatively stained preparations . The C . crescentus filament appears, both in negative stain and in the frozen-hydrated state, significantly smoother and narrower than other filaments . Its helical symmetry, and unit cell size, however, are similar to that of other filaments . Although the molecular weight of the C . crescentus flagellin is about half that of other plain flagellins, there is only one monomer per unit cell as indicated by diffraction studies and by linear mass density measurements with the scanning transmission electron microscope . Alignment of the primary amino acid sequences of Salmonella typhimurium (serotype i) and C . crescentus (29,000 Mr) flagellins shows that whereas there is homology at the amino and carboxyterminal ends of the two sequences, the central segment of the S . typhimurium sequence has no homology to that of C . crescentus . A correlated comparison between the three-dimensional reconstructions of the two filaments and primary amino acid sequences of the two flagellins suggests that: (1) the C . crescentus subunit is missing the outer molecular domain but is, otherwise, similar to that of S . typhimurium; (2) the outer molecular domain in S . typhimurium corresponds, therefore, to a central stretch of the primary amino acid sequence; and (3) the outer molecular domain, missing in C . crescentus, is not obligatory for flagellar motility.

Carcinogenesis, 1988 Aug, 9(8), 1513 - 5
Modifying role of vitamins on the mutagenic action of N-methyl-N'-nitro-N-nitrosoguanidine; Shetty TK et al.; Several vitamin compounds have been tested for their ability to suppress the mutagenicity of N-methyl-N'-nitro-N-nitrosoguanidine, a direct acting mutagen/carcinogen, in Salmonella typhimurium strain TA100 . Menadione, alpha-tocopherol, retinal and retinol have displayed high inhibitory activity . The antimutagenic activity of menadione, in particular, has been found to be remarkable in as much as less than equimolar amount can reduce the mutagenic potency of the carcinogen by 50% . In vitro data suggest that its action is mediated by accelerating the deactivation of the N-nitroso carcinogen, possibly involving the formation of a quinone radical.

J Appl Toxicol, 1988 Aug, 8(4), 243 - 8
In vitro mutagenicity of water contaminants in complex mixtures; Varma MM et al.; Trihalomethanes, Carbon tetrachloride and trichloroethylene were tested in single, binary and multi-complex mixtures using standard tester strains TA1535, TA1537, TA98 and TA100 of Salmonella typhimurium with and without addition of an in vitro metabolizing fraction S-9 . Chloroform (CHCl3) was found to be mutagenic in all strains without S-9 activation . However, when tested with Bromoform (15%), which was nonmutagenic singly, the combined effect of the mixture was nonmutagenic . CCl4 was a direct mutagen (without S-9) in all strains except TA 1535 . When combined with 85% CHCl3, only strains TA1535 and TA1537 were mutagenic . When tested with mammalian activation (S-9), CCl4 was mutagenic in all strains . However, when tested with CHCl3 (CHCl3 and CCl4-85:15), the mutagenic capability was lost . With or without S-9 Activation multi-complex mixture of CHCl3, CCl4 and TCE (85:8:7) was mutagenic for a narrow range of doses in all strains.

J Med Microbiol, 1988 Aug, 26(4), 281 - 4
Changes in hepatic superoxide dismutase and xanthine oxidase activity in mice infected with Salmonella typhimurium and Pseudomonas aeruginosa; Takahashi M et al.; Liver xanthine oxidase (XOD) and superoxide dismutase (SOD) activities were compared in mice during Salmonella typhimurium and Pseudomonas aeruginosa infections . We observed that XOD activity rose but SOD activity fell for the first 11 days after infection with smooth type S . typhimurium, coinciding with the period of bacterial growth in the liver . Rough type S . typhimurium did not establish an infection and mice inoculated with this strain showed no variation in enzyme activities . P . aeruginosa infection was mild but stimulated both XOD and SOD activities.

Jpn J Genet, 1988 Aug, 63(4), 343 - 57
Cloning and nucleotide sequence of the brnQ gene, the structural gene for a membrane-associated component of the LIV-II transport system for branched-chain amino acids in Salmonella typhimurium; Ohnishi K et al.; The genetically defined gleR-brnQ region responsible for the branched-chain amino acid transport in Salmonella typhimurium was mapped in the 3.3-kilobase SalI-PstI segment of plasmid pOH56 by complementation analysis . By subcloning and genetic recombination analysis, the gleR and brnQ3 mutational sites were localized within the 0.85-kilobase SalI-EcoRV segment, and brnQ4 within the 0.8-kilobase EcoRV-HindIII segment . The nucleotide sequence of the brnQ gene and its flanking regions was determined . The brnQ gene is encoded by the sequence starting 24 base pairs upstream from the EcoRV site . Transcription of the brnQ gene starts at three sites separated by 171, 173 and 174 nucleotides, respectively, from the initiation codon . The promoter sequences can be seen in the immediate upstream region of the transcription initiation sites . There is a long silent region between the transcription initiation sites and a potential Shine-Dalgarno nucleotide sequence . The coding sequence of the brnQ gene, which is 1317 base pairs long, specifies a very hydrophobic protein of 439 amino acid residues.

Food Chem Toxicol, 1988 Aug, 26(8), 691 - 8
Impaired murine resistance to Salmonella typhimurium following oral exposure to the trichothecene T-2 toxin; Tai JH et al.; On orally exposing Salmonella-resistant C3H/HeN mice to the trichothecene T-2 toxin (1 mg/kg body weight), challenging with Salmonella typhimurium, and continuing to dose with T-2 toxin on alternate days for 3 wk, the LD50 for the organism decreased by five orders of magnitude, in comparison with control mice not treated with T-2 toxin . In the absence of S . typhimurium, T-2 toxin did not cause lethal effects when administered at this level . Increased mortality in response to S . typhimurium challenge was dependent on T-2 toxin dose in the range 0 to 1 mg/kg for this regimen . The toxin did not significantly affect intestinal infection but did increase splenic counts in mice challenged with a range of S . typhimurium doses and also accelerated body-weight loss in infected animals . Mice challenged with the organism exhibited similar mortality when T-2 toxin treatment was begun 1 day prior to infection or at 5 or 9 days after infection . A time-related decrease in mortality, relative to that found for the standardized co-challenge described above, was observed when T-2 toxin administration was begun at 9, 13 or 23 days after infection . The results indicated that, depending on the challenge dose of the organism, both early and late phase acquired immune response to S . typhimurium could be impaired by T-2 toxin . Markedly enhanced susceptibility to gram-negative bacterial infection is another manifestation of trichothecene toxicity and may be an important aetiological factor in animal health problems that are associated with these mycotoxins.

Toxicol Lett, 1988 Aug, 42(2), 193 - 8
Effect of certain trace elements on the mutagenicity of N-methyl-N'-nitro-N-nitrosoguanidine; Francis AR et al.; Tests have been carried out to detect inhibitory activity of various trace elements on mutagenesis induced by the carcinogen N-methyl-N'-nitro-N-nitrosoguanidine in Salmonella typhimurium strain TA100 . Selenium has been found to be most active in this regard while copper has displayed moderate inhibitory ability . The action of selenium is mediated through an interaction resulting in rapid deactivation of the carcinogen.

J Bacteriol, 1988 Aug, 170(8), 3627 - 32
Pausing of flagellar rotation is a component of bacterial motility and chemotaxis; Lapidus IR et al.; When bacterial cells are tethered to glass by their flagella, many of them spin . On the basis of experiments with tethered cells it has generally been thought that the motor which drives the flagellum is a two-state device, existing in either a counterclockwise or a clockwise state . Here we show that a third state of the motor is that of pausing, the duration and frequency of which are affected by chemotactic stimuli . We have recorded on video tape the rotation of tethered Escherichia coli and Salmonella typhimurium cells and analyzed the recordings frame by frame and in slow motion . Most wild-type cells paused intermittently . The addition of repellents caused an increase in the frequency and duration of the pauses . The addition of attractants sharply reduced the number of pauses . A chemotaxis mutant which lacks a large part of the chemotaxis machinery owing to a deletion of the genes from cheA to cheZ did not pause at all and did not respond to repellents by pausing . A tumbly mutant of S . typhimurium responded to repellents by smooth swimming and to attractants by tumbling . When tethered, these cells exhibited a normal rotational response but an inverse pausing response to chemotactic stimuli: the frequency of pauses decreased in response to repellents and increased in response to attractants . It is suggested that (i) pausing is an integral part of bacterial motility and chemotaxis, (ii) pausing is independent of the direction of flagellar rotation, and (iii) pausing may be one of the causes of tumbling.

J Bacteriol, 1988 Aug, 170(8), 3509 - 12
Mode of peptidoglycan synthesis in Salmonella typhimurium: single-strand insertion; Cooper S et al.; The synthesis of peptidoglycan by Salmonella typhimurium at the molecular level has been analyzed by studying the pattern of insertion of newly synthesized strands into the preexisting cell wall . We have measured the acceptor-donor radioactivity ratio during short labeling periods, and we found values between 0 and 0.2 . This is less than the ratio observed by Burman and Park (Proc . Natl . Acad . Sci . USA, 81:1844-1848) for peptidoglycan synthesis in Escherichia coli . We propose that insertion of new strands occurs as single strands.

J Bacteriol, 1988 Aug, 170(8), 3421 - 6
Nucleotide sequence and transcription start point of the phosphoglycerate transporter gene of Salmonella typhimurium; Goldrick D et al.; We identified the phosphoglycerate transporter gene of Salmonella typhimurium and its polypeptide product and determined the nucleotide sequence of the gene . The predicted translation product was a protein of 406 amino acid residues and was extremely hydrophobic, a feature that is consistent with its role in membrane transport . Hydropathy analysis suggested that there are eight transmembrane segments of at least 20 amino acid residues for the protein . The transcription start point was mapped to lie at position -44 relative to the putative translational initiation start point . Comparison of PgtP with UhpT and GlpT, the membrane-bound proteins involved in the transport of hexose-6-phosphate and glycerol-3-phosphate, respectively, revealed a very high degree of amino acid sequence similarity among them, reflecting not only similar structures and functions among these polypeptides but also a common evolutionary origin for them.

Epidemiol Infect, 1988 Aug, 101(1), 75 - 82
Salmonella typhimurium phage type 141 infections in Sheffield during 1984 and 1985: association with hens' eggs; Chapman PA et al.; Food poisoning due to Salmonella typhimurium phage type 141 was unusual in the Sheffield area before 1984 . The sudden increase in incidence of this phage type during 1984 and 1985, and its causative role in several small outbreaks in this period have been investigated . Epidemiological and laboratory investigations suggested that hens' eggs were the most likely source of S . typhimurium phage type 141.

EMBO J, 1988 Aug, 7(8), 2611 - 7
Overproduction of peroxide-scavenging enzymes in Escherichia coli suppresses spontaneous mutagenesis and sensitivity to redox-cycling agents in oxyR-mutants; Greenberg JT et al.; Mutations that suppressed the H2O2 sensitivity of Escherichia coli oxyR- strains caused elevated levels of one three enzymes that destroy organic and hydrogen peroxides: catalase-hydroperoxidase I (the katG gene product), catalase-hydroperoxidase II (controlled by katEF) or alkyl hydroperoxide reductase (specified by the ahp genes) . The continuous high-level expression of any one of these enzymes also conferred resistance in an oxyR deletion mutant against other compounds such as N-ethylmaleimide and the superoxide-generator menadione . Overproduction of alkyl hydroperoxide reductase, but not of the catalases, gave resistance to the organic oxidant cumene hydroperoxide . The E . coli delta oxyR strains also exhibited a strongly elevated frequency of spontaneous mutagenesis, as reported for such mutants in Salmonella typhimurium . This mutagenesis was greatly diminished by the individual overexpression of these scavenging enzymes . All of these phenotypes--enzyme overproduction, resistance to oxidants and suppression of spontaneous mutagenesis--remained linked upon transduction of the mutant katG or ahp genes . Peroxides thus appear to mediate the toxicity of a variety of redox agents, and are produced in sufficient quantity during normal metabolism to cause a substantial increase in 'spontaneous' mutations in cells that lack adequate antioxidant defenses.

Mol Gen Genet, 1988 Aug, 213(2-3), 332 - 8
Characterization of Tn10d-Cam: a transposition-defective Tn10 specifying chloramphenicol resistance; Elliott T et al.; We have constructed a small, transposition-defective derivative of the transposon Tn10 that carries the chloramphenicol acetyltransferase gene of pACYC184 . This new genetic element, Tn10d-Cam, transposes when Tn10 transposase is provided from a multi-copy plasmid . Transposon insertion mutagenesis of Salmonella typhimurium was performed by using a strain carrying a Tn10d-Cam insertion in an Escherichia coli F' episome as the donor in transductional crosses into recipients that carried a plasmid expressing Tn10 transposase . Tn10d-Cam insertion mutations were also generated by complementation in cis of Tn10d-Cam by a cotransducible Tn10 element that overproduces transposase . Here, transposase was provided only transiently, and the Tn10d-Cam insertion mutations were recovered in a transposase-free strain . Cis complementation was used for mutagenesis of a plasmid target . The site specificity of insertion and the effect of insertions on expression of a downstream gene were investigated, using Tn10d-Cam insertions in a plasmid carrying a segment of the histidine operon.

J Bacteriol, 1988 Aug, 170(8), 3725 - 30
Salmonella typhimurium mutants lacking NAD pyrophosphatase; Park UE et al.; NAD can serve as both a purine and a pyridine source for Salmonella typhimurium . Exogenous NAD is rapidly broken down into nicotinamide mononucleotide and AMP by an NAD pyrophosphatase, the first step in the pathway for the assimilation of exogenous NAD . We isolated and characterized mutants of S . typhimurium lacking NAD pyrophosphatase activity; such mutants were identified by their failure to use exogenous NAD as a purine source . These mutants carry mutations that map at a new locus, designated pnuE, between 86 and 87 min on the Salmonella chromosome.

J Bacteriol, 1988 Aug, 170(8), 3682 - 8
Dominant lethal mutations in the dnaB helicase gene of Salmonella typhimurium; Maurer R et al.; A class of dominant lethal mutations in the dnaB (replicative helicase) gene of Salmonella typhimurium is described . The mutated genes, when present on multicopy plasmids, interfered with colony formation by Escherichia coli host strains with a functional chromosomal dnaB gene . The lethal phenotype was expressed specifically in supE (glutamine-inserting) host strains and not in Sup+ strains, because the mutant genes, by design, also possessed an amber mutation derived from a glutamine codon . Mutations located at 11 sites by deletion mapping and DNA sequence analysis varied in the temperature dependence and severity of their lethal effects . None of the mutations complemented a dnaB(Ts) host strain at high temperature (42 degrees C) . Therefore, these nonfunctional DnaB proteins must engage some component(s) of the DNA replication machinery and inhibit replication . These mutations are predicted to confer limited, specific defects in either the catalytic activity of DnaB or the ability of DnaB to interact with one of its ligands such as DNA, nucleotide, or another replication protein . The variety of mutant sites and detailed phenotypes represented in this group of mutations may indicate the operation of more than one specific mechanism of lethality.

Proc Natl Acad Sci U S A, 1988 Aug, 85(15), 5620 - 4
Chromosomal location and structure of the operon encoding peptide-chain-release factor 2 of Escherichia coli; Kawakami K et al.; The prfB gene encodes peptide-chain-release factor 2 of Escherichia coli, which catalyzes translation termination at UGA and UAA codons . The gene, identified by sequencing, is located at the 62-min region of the E . coli chromosome . The prfB gene is followed by an open reading frame encoding a 57,603-Da protein . This downstream open reading frame was identified as herC, a gene defined by a suppressor mutation that restores replication of a ColE1 plasmid mutant . RNA blot hybridization and S1 nuclease protection analyses of in vivo transcripts showed that prfB and herC are cotranscribed into a 2800-base transcript in the counterclockwise direction with respect to the E . coli genetic map . Thus, we refer to the two genes as the prfB-herC operon . Data are presented that suggest that supK, a mutation in Salmonella typhimurium that suppresses UGA termination, is the structural gene for Salmonella release factor 2 . Translation control within the prfB-herC operon and the relationship of these genes to a tRNA methyltransferase are discussed.

Nucleic Acids Res, 1988 Jul 25, 16(14B), 6789 - 802
IS150: distribution, nucleotide sequence and phylogenetic relationships of a new E . coli insertion element; Schwartz E et al.; Recently we identified the new insertion (IS) sequence IS150 in various strains of Escherichia coli K-12 . We have screened other strains of E . coli and Salmonella typhimurium for the presence of homologous sequences . The strains of E . coli K-12 and W tested contain one or more copies of homology to IS150 . We have also determined the complete nucleotide sequence of a copy of IS150 inserted into IS1 . Comparison of nucleotide and deduced amino acid sequences of IS150, IS2, IS3, IS51, IS600 and IS629 reveals significant homologies suggesting that these elements are members of a family of phylogenetically related insertion sequences.

Med J Aust, 1988 Jul 18, 149(2), 94 - 5
Mycotic aneurysm of the thoracic aorta caused by Salmonella typhimurium; Golledge CL et al.; A fatal case of mycotic aneurysm of the thoracic aorta is described . Salmonella typhimurium was isolated from blood cultures and from cultures of a post-mortem sample of the aneurysm . A review of the literature showed that while endovascular infection is a recognized complication of salmonellal septicaemia in the elderly, infection of the thoracic aorta by Salmonella spp . is rare . A combination of surgery and antibiotic therapy always is required for a successful outcome.

J Biol Chem, 1988 Jul 5, 263(19), 9155 - 61
The yeast SEC53 gene encodes phosphomannomutase; Kepes F et al.; Yeast sec53 cells incubated at a restrictive temperature (37 degrees C) accumulate inactive and incompletely glycosylated forms of secretory proteins within the lumen of the endoplasmic reticulum . A defect in glycosylation of alpha-factor precursor has been reproduced in vitro using membranes and cytosol isolated from sec53 mutant cells . Normal glycosylation is restored in reactions supplemented with a cytosolic fraction from wild type cells, with GDP-mannose, or with mannose 1-phosphate and GTP, but not with mannose 6-phosphate and GTP . This pattern of stimulation suggests that extracts of sec53 cells are deficient in phosphomannomutase activity or in the production of a precursor of mannose 1-phosphate . Several lines of evidence demonstrate that SEC53 encodes the yeast phosphomannomutase . Direct assay of soluble fractions from independent alleles of sec53 shows low to negligible phosphomannomutase, but nearly normal levels of phosphomannoisomerase activity . The residual phosphomannomutase activity in mutant cell lysates is thermolabile in proportion to the severity of the sec53 cell growth defect . Introduction of the SEC53 gene on a multicopy plasmid into sec53 or wild type yeast and into Salmonella typhimurium results in an increase in phosphomannomutase activity that correlates with elevated expression of the Sec53 protein . Finally, the Sec53 protein and phosphomannomutase activity cofractionate exactly in a 70-fold partial purification involving gel filtration and DEAE chromatography . The secretory defect in sec53 cells may now be explained by a deficit in GDP-mannose production.

FEBS Lett, 1988 Jul 4, 234(1), 165 - 8
Inaccurate protein synthesis in a mutant of Salmonella typhimurium defective in transfer RNA pseudouridylation; Negre D et al.; Protein synthesis was studied comparatively in a wild-type strain of Salmonella typhimurium and in hisT mutant cells defective in the pseudouridylation of transfer RNA . From a quantitative point of view, no significant differences between the two types of strain was observed when measuring the rate of protein synthesis during either exponential growth or starvation for histidine . In contrast, the qualitative analysis of proteins by two-dimensional gel electrophoresis showed that histidine-starved hisT cells mistranslate the genetic program at a higher frequency than exponentially growing hisT cells or either starved or unstarved hisT+ cells.

J Dairy Sci, 1988 Jul, 71(7), 1756 - 63
Separation of immunoglobulin and transferrin from blood serum and plasma by metal chelate interaction chromatography; Al-Mashikhi SA et al.; Metal chelate interaction chromatography was used to separate Ig, transferrin, and albumin from blood serum and blood plasma . A column was packed with iminodiacetic acid: 1,4-butanediol diglycidyl Sepharose 6B or Sephacryl S-300 and loaded with copper, zinc, nickel, or cobalt ion . Radial immunodiffusion assay indicated that Ig-rich fractions of blood serum obtained from Zn-, Ni-, Co-, and Cu-loaded columns contained 23.2, 81.3, 79.4, and 98.1% active IgG, respectively . Transferrin was recovered from the second peak . When the same conditions of metal chelate interaction chromatography were used for blood plasma, hemoglobin tended to bind strongly to the Cu-loaded column and was eluted only with 50% ethanol . Modification of histidine residues in Ig and transferrin with diethyl pyrocarbonate almost completely destroyed their binding ability to the column . Immunoglobulin G separated showed antilipopolysaccharide antibody activity against Escherichia coli, Salmonella typhimurium, and Bordettella parapertussis.

Carcinogenesis, 1988 Jul, 9(7), 1277 - 81
Metabolism and mutagenic activity of benzo{k}fluoranthene and 3-, 8- and 9-fluorobenzo{k}fluoranthene; Weyand EH et al.; The metabolism of 3-, 8- and 9-fluorobenzo{k}fluoranthene (B{k}F) relative to B{k}F was investigated . The major metabolites of B{k}F formed in vitro using rat liver S-9 metabolism systems were 8,9-dihydro-8,9-dihydroxyB{k}F, the 2,3-quinone of B{k}F and 3-, 8- and 9-hydroxyB{k}F . Fluorine substitution within the structure of B{k}F substantially altered the types of metabolites formed in vitro . The most pronounced effect was observed with 9-fluoroB{k}F . In contrast to B{k}F, the 8,9-dihydro-8,9-dihydroxy-, 9-hydroxy- and 10,11-dihydro-10,11-dihydroxy derivatives were not detected as metabolites of 9-fluoroB{k}F . However, either the 2,3- or 4,5-dihydrodiol of 9-fluoroB{k}F was detected . In the case of 8-fluoroB{k}F, neither the 8- nor 11-hydroxy- derivatives were detected . The principle dihydrodiols formed from 8-fluoroB{k}F were the 10,11-dihydrodiol and either the 2,3-or 4,5-dihydrodiol . The pattern of metabolites formed with 3-fluoroB{k}F was similar to that observed with B{k}F with the exception that neither the 3- nor 4-hydroxy derivatives were formed . Mass spectral data indicated that fluoro substitution is not lost to any appreciable extent during the metabolism of 3-, 8- and 9-fluoroB{k}F . The mutagenic activity of these B{k}F fluoro derivatives along with B{k}F, 2,3-dihydro-2,3-dihydroxyB{k}F, the 2,3-quinone of B{k}F and 8,9-dihydro-8,9-dihydroxyB{k}F were evaluated in Salmonella typhimurium TA100 in the presence of rat liver S-9 metabolism systems . 3-FluoroB{k}F was more mutagenic than B{k}F, while both 8- and 9-fluoroB{k}F were less active . While the 2,3-dihydrodiol and 2,3-quinone were weakly active, the 8,9-dihydrodiol had similar mutagenic potency to B{k}F.

J Exp Med, 1988 Jul 1, 168(1), 25 - 32
Protective immunity evoked by oral administration of attenuated aroA Salmonella typhimurium expressing cloned streptococcal M protein; Poirier TP et al.; Attenuated strains of Salmonella have been used effectively as vaccines against typhoid fever . We have investigated the use of such strains to deliver cloned antiphagocytic virulence determinants of unrelated bacteria . The aroA strain of S . typhimurium SL3261 was transformed with a low-copy plasmid vector pMK207, which contains the cloned gene spm5 encoding streptococcal M protein, the major virulence factor of these organisms . The transformed SL3261 expressed type 5 M protein in the cytoplasmic fraction, and when fed orally to BALB/c mice, evoked both serum and salivary IgA, IgG, and IgM antibodies directed against type 5 M protein . The orally immunized mice were completely protected against both intranasal and intraperitoneal challenge infections with virulent S . typhimurium SL1344 or M5 streptococci . These studies provide evidence that an attenuated strain of Salmonella can be used effectively as a general vaccine vehicle to deliver antiphagocytic virulence determinants of unrelated bacteria.

J Bacteriol, 1988 Jul, 170(7), 3150 - 7
DNA sequences of the cysK regions of Salmonella typhimurium and Escherichia coli and linkage of the cysK regions to ptsH; Byrne CR et al.; Nucleotide sequences of the cysK regions of Salmonella typhimurium and Escherichia coli have been determined . A total of 3,812 and 2,595 nucleotides were sequenced from S . typhimurium and E . coli, respectively . Open reading frames of 323 codons were found in both species and were identified as those of cysK by comparison of deduced amino acid sequences with amino- and carboxyl-terminal amino acid analyses of the S . typhimurium cysK gene product O-acetylserine (thiol)-lyase A . The two cysK DNA sequences were 85% identical, and the deduced amino acid sequences were 96% identical . The major transcription initiation sites for cysK were found to be virtually identical in the two organisms, by using primer extension and S1 nuclease protection techniques . The -35 region corresponding to the major transcription start site was TTCCCC in S . typhimurium and TTCCGC in E . coli . The deviation of these sequences from the consensus sequence TTGACA may reflect the fact that cysK is subject to positive control and requires the cysB regulatory protein for expression . Sequences downstream of cysK were found to include ptsH and a portion of ptsI, thus establishing the exact relationship of cysK with these two genes . A 290-codon open reading frame, which may represent the cysZ gene, was identified upstream of cysK.

J Dairy Sci, 1988 Jul, 71(7), 1747 - 55
Separation of immunoglobulins and lactoferrin from cheese whey by chelating chromatography; Al-Mashikhi SA et al.; Different adsorption and chelating chromatographic methods were used to isolate immunoglobulins and lactoferrin from cheese whey . Among three adsorption solid supports (silica, controlled pore glass, and alumina), controlled pore glass showed the highest adsorption of immunoglobulins; however, its capacity was low . 1,4-Butanediol diglycidyl etheriminodiacetic acid on Sepharose 6B was loaded with copper ion and used for the same purpose . Of the two peaks eluted using pH gradient, the first yellowish peak was rich in lactoferrin and the second was rich in Ig . The purity of IgG in the Ig rich fraction as indicated by radial immunodiffusion was 77.2 and 53.0% for acid whey and Cheddar cheese whey, respectively . The capacity of the column was high; a 25-ml copper charged column could absorb Ig from 1 L of cheese whey . Modification of histidine residues in Ig with diethyl pyrocarbonate almost completely eradicated the adsorption, implicating the coordination compound formation between histidine in Ig and Cu on the chelating column as the adsorption mechanism . Enzyme-linked immunosorbent assays of the Ig thus separated demonstrated their binding activity against lipopolysaccharides extracted from Escherichia coli, Salmonella typhimurium, and Bordetella parapertussis.

Biochem Pharmacol, 1988 Jul 1, 37(13), 2585 - 93
Preparation, toxicity and mutagenicity of 1-methyl-2-nitrosoimidazole . A toxic 2-nitroimidazole reduction product; Noss MB et al.; 1-Methyl-2-nitrosoimidazole (INO), the 2-electron reduction product of 1-methyl-2-nitroimidazole (INO2), was prepared by electrochemical reduction of INO2 to 2-hydroxylamino-1-methyl-imidazole (INHOH), followed by back oxidation with iodine . Although stable in crystalline form, INO reacted in water, phosphate-buffered saline, and mammalian cell growth medium . Half-lives for decay were determined by UV-visible spectroscopy . INO was found to be highly toxic towards Chinese hamster ovary (CHO) cells, concentrations of 10-60 microM producing significant cytotoxicity . The rate of INO decay was found to be increased in the presence of CHO cells . INO was also toxic and mutagenic towards Salmonella typhimurium TA-100 . When compared on a molar basis to the parent nitro compound INO2, and the 4- and 6-electron reduction products INHOH and 2-amino-1-methylimidazole (INH2), INO was by far (two orders of magnitude) the most toxic under aerobic conditions . These results suggest that the nitroso reduction product of 2-nitroimidazoles may be the reduced species responsible for hypoxic cell selective toxicity of 2-nitroimidazoles.

Am J Vet Res, 1988 Jul, 49(7), 1188 - 92
Differential effect of T-2 toxin on murine host resistance to three facultative intracellular bacterial pathogens: Listeria monocytogenes, Salmonella typhimurium, and Mycobacterium bovis; Ziprin RL et al.; The effect of T-2 toxin, a radiomimetic immunosuppressive agent, on resistance to the facultative intracellular bacterial pathogens Listeria monocytogenes (strain EGD), Mycobacterium bovis (BCG Copenhagen 1331), and Salmonella typhimurium was determined . Female Swiss ICR mice were given a single dose of T-2 toxin (4 mg/kg of body weight) by gastric gavage . On the seventh day after toxin administration, the mice were infected by intraperitoneal inoculation with L monocytogenes, S typhimurium, or M bovis . Mice given the toxin also were exposed to respirable droplet nuclei containing L monocytogenes or M bovis . The effect of the toxin on the course of infection was monitored by observing mortality or by enumeration of bacteria in the spleen or lungs of infected mice . The toxin increased resistance to infection with L monocytogenes initiated by intraperitoneal inoculation, but reduced resistance to M bovis infection initiated by intraperitoneal inoculation . The toxin had no appreciable effect on the course of salmonellosis or on resistance to infection initiated by inhalation of L monocytogenes or M bovis aerosols . Therefore, it was concluded that T-2 toxin does not necessarily reduce resistance to infection in mice . The toxin's effect on the course of in vivo bacterial infections depends on the nature of the infective agent and the route of inoculation.

Plasmid, 1988 Jul, 20(1), 10 - 6
Genetic and molecular characterization of an epidemic plasmid coding for multidrug resistance in Salmonella typhimurium of human origin; Sharma PL et al.; All 201 multidrug resistant Salmonella typhimurium strains isolated from epidemics in India contained nonconjugative (157 strains) or conjugative (44 strains) Inc F1me multiresistance plasmids . Two small R-plasmids of 7 MDa which coded for resistance to either ampicillin or streptomycin and sulfamethoxazole were also detected along with other plasmids . The small plasmids were members of group 1 and group 2 incompatibility groups . Restriction endonuclease analysis of conjugative (96 MDa) and nonconjugative (88 MDa) Inc F1me plasmids showed considerable similarity except for the presence of unique fragments among both the groups and the loss of fragments corresponding to the smaller size of the nonconjugative plasmid . A single Inc F1me plasmid appears responsible for various outbreaks of multiresistant S . typhimurium in different parts of India.

Mutagenesis, 1988 Jul, 3(4), 349 - 53
Mutagenicity of furoquinoline alkaloids in the Salmonella/microsome assay . Mutagenicity of dictamnine is modified by various enzyme inducers and inhibitors; Hafele F et al.; Furoquinoline alkaloids are activated to mutagens by microsomal preparations of rat liver . The mutagenic effects decrease with the increasing number of methoxyl-substituents on the furoquinoline skeleton . After metabolic activation dictamnine, gamma-fagarine and skimmianine exhibit strong mutagenicity in Salmonella typhimurium strains TA98 and TA100 and have comparatively little or no activity in the corresponding non-R-factor strains TA1538 and TA1535 . This indicates that these compounds primarily act as frameshift mutagens . The activation capacity of the metabolizing mixture depends on the amount of microsomal protein . Pretreatment of male Wistar rats with phenobarbital (Pb) or 3-methylcholanthrene results in an increase in the metabolic capacity of the corresponding liver microsome preparations, Pb induction showing the greater effect . Various enzyme inhibitors, such as carbon monoxide, metyrapone, SKF-525A, 7,8-benzoflavone and methimazole, decrease the activation capacities of rat liver preparations, whereas 1,1,1-trichloropropene-2,3-oxide has no effect . These results suggest that furoquinolines are activated to mutagenic metabolites by cytochrome-P-450 and cytochrome-P-448, and possibly by the flavin-containing monooxygenase.

Mutagenesis, 1988 Jul, 3(4), 323 - 8
Inter-individual variation in the mutagenic activation of 2-acetylaminofluorene by human liver in relation to animal metabolic models; Smith AJ et al.; A relatively large, reproducible inter-individual variation was found in the ability of 17 human liver S9 samples to mediate the mutagenicity of 2-acetylaminofluorene (2AAF) in Salmonella typhimurium strain TA98 . In an animal model, variation in metabolic activation of 2AAF did not appear to relate to the phenotype of debrisoquine 4-hydroxylase since hepatic S9 from poor and extensive metabolizer phenotypes (female DA and female Wistar rat, respectively) mediated the mutagenicity of this aromatic amide equally well . Approximately one-third of human liver samples exhibited an ability to detoxify 2AAF in a modified bacterial mutagenicity assay in a manner similar to that shown by guinea pig (but not rat or rabbit) S9 . However, only in 2/14 human preparations was the detoxification inhibited by 8-hydroxyquinoline which has previously been recognized as an inhibitor of a detoxifying 'transoxygenation' in guinea pig liver . The results support a growing body of evidence for inter-individual variation in human carcinogen metabolism which may be important in determining susceptibility to chemical carcinogenesis.

Mutagenesis, 1988 Jul, 3(4), 303 - 9
Genotoxic activity of the N-acetylated metabolites of the food mutagens 2-amino-3-methylimidazo{4,5-f}quinoline (IQ) and 2-amino-3,4-dimethylimidazo{4,5-f}quinoline (MeIQ); Brunborg G et al.; The genotoxic potential of the food mutagens 2-amino-3-methylimidazo{4,5-f}quinoline (IQ) and 2-amino-3,4-dimethylimidazo{4,5-f}quinoline (MeIQ) and their N-acetylated metabolites (AcIQ and AcMeIQ, respectively) has been studied, in order to evaluate whether an initial N-acetylation of IQ or MeIQ is important for the overall in vivo genotoxicity of the compounds . When incubated with uninduced (control) rat hepatocytes, both the acetylated and the unacetylated compounds appeared to be relatively stable, whereas water-soluble metabolites (i.e . not extractable by ethyl acetate at alkaline pH) were rapidly formed with hepatocytes from PCB-induced animals . No DNA damage was induced by IQ or MeIQ in hepatocytes isolated from control rats, as measured by alkaline elution . In hepatocytes from PCB-pretreated rats, IQ, MeIQ, AcIQ and AcMeIQ induced DNA damage at low (10(-6) M) concentrations, with AcIQ being more potent than IQ whereas AcMeIQ was less potent than MeIQ . Similar patterns were observed when unscheduled DNA synthesis was measured in hepatocytes . The compounds induced sister chromatid exchanges in Chinese hamster V79 cells with PCB-induced hepatocytes as activation system; IQ and AcIQ were equal while AcMeIQ had less activity than MeIQ . The compounds were also compared in bacterial mutagenesis test systems (Salmonella typhimurium TA98) . With hepatocyte activation, AcIQ was slightly more potent than IQ, whereas AcMeIQ was markedly less mutagenic than MeIQ . With subcellular fractions as activation system (rat liver S9 or microsomes), the N-acetylated compounds were similar to or less mutagenic than their parent compounds . The mutagenic effects of AcIQ and AcMeIQ in bacteria with microsomal activation were markedly reduced by the deacetylase inhibitor paraoxon.(ABSTRACT TRUNCATED AT 250 WORDS)

Mutagenesis, 1988 Jul, 3(4), 293 - 6
Anti-mutagenicity of catechin against environmental mutagens; Nagabhushan M et al.; Catechu is the non-mutagenic component of betel quid . We have tested catechu extract and catechin for anti-mutagenic activity in Salmonella typhimurium strain TA98 against environmental mutagens relevant to India . Catechu extract, as well as catechin, shows a dose-dependent decrease in the mutagenicity of tobacco and masheri extracts, and bidi and cigarette smoke condensates in TA98 with S9 mix . Mutagenicity of extracts of charred and non-charred meat in TA98 is also inhibited by catechu extract and catechin in a dose-dependent manner with or without S9 mix.

Food Chem Toxicol, 1988 Jul, 26(7), 631 - 5
The genotoxic activity of glycerol in an in vitro test battery; Doolittle DJ et al.; Glycerol, a widely distributed constituent of food and an additive used in cigarette manufacture, has been tested for genotoxic potential in a battery of short-term genotoxicity assays . Glycerol was evaluated in the Ames Salmonella typhimurium mutagenesis assay (strains TA98, TA100, TA1535, TA1537 and TA1538), in the rat hepatocyte unscheduled DNA synthesis assay, in the Chinese hamster ovary (CHO) chromosome aberration assay, the CHO sister chromatid exchange assay and the CHO mammalian mutagenesis assay . All assays (except the rat hepatocyte unscheduled DNA synthesis assay) were conducted both with and without the addition of Aroclor-induced rat liver S-9 . The results of all tests were negative, showing that neither glycerol nor its metabolites have genotoxic activity in the battery of tests used.

Radiobiologiia, 1988 Jul-Aug, 28(4), 563 - 5
{Biological action of plutonium-239 on Salmonella typhimurium}; Gafieva ZA et al.; Salmonella typhimurium cells were exposed in a 239Pu citrate solution . Cell death and induction of gene mutations were an exponential function of gamma radiation dose . LD37 was 34.8 Gy; mutation doubling dose, 19 Gy.

J Bacteriol, 1988 Jul, 170(7), 3032 - 9
Pilin-gene phase variation of Moraxella bovis is caused by an inversion of the pilin genes; Marrs CF et al.; Moraxella bovis Epp63 can express either of two different pilin proteins, called alpha and beta . We have previously cloned and sequenced the beta-pilin gene and now report that DNAs isolated from bacteria expressing alpha pilin have hybridization patterns consistently different from those of bacteria expressing beta pilin . The phase variation between alpha- and beta-pilin gene expression appears to be associated with an inversion of about 2 kilobases of DNA, whose endpoints occur within the coding region of the expressed pilin gene . Comparisons of the beta-pilin gene sequence with those of well-studied bacterial inversion systems revealed a stretch of 58% sequence similarity (21 of 36 base pairs) between the left inverted repeat of the Salmonella typhimurium flagellar hin control region and the amino-terminal portion of the beta-pilin gene.

Mol Gen Genet, 1988 Jul, 213(1), 125 - 33
Regulation of proline utilization in Salmonella typhimurium: molecular characterization of the put operon, and DNA sequence of the put control region; Hahn DR et al.; The two genes required for proline utilization (put) in Salmonella typhimurium form a divergent operon . Extensive genetic evidence suggests that transcription of the put operon is autoregulated by the putA gene product, a membrane-associated dehydrogenase . In order to understand the mechanism of regulation, we characterized plasmid clones of the put operon . A 7.5 kb clone contains both of the put structural genes and regulatory sites . This clone only expressed two unique proteins corresponding to the putA and putP gene products . By comparing the physical and genetic maps of the put operon, the position of the put regulatory region was defined and the DNA sequence of this region was determined . Analysis of the DNA sequence indicated several potential regulatory sites for the put genes . Based on genetic and physical mapping studies, the most likely regulatory sites are two convergent promoters approximately 30 bp apart . A 27 bp palindrome located between the two promoters may be the operator for autoregulation by the PutA protein . The putA translational start site is 40 bp downstream of its putative mRNA start site . The putP promoter and its translational start site are separated by a 400 bp untranslated region.

Zh Mikrobiol Epidemiol Immunobiol, 1988 Jul, (7), 9 - 11
{Effect of cyclic 3,5-adenosine monophosphate on the virulence of Salmonella typhimurium}; Boichenko MN et al.; To study the role of cAMP in the virulence of S . typhimurium, cAMP-producing plasmid pTG 4 was transferred to cAMP-deficient S . typhimurium mutant . The transfer of the plasmid enhanced the virulence of the microorganisms due to the increased destruction of macrophages and the intensified multiplication of salmonellae in the spleen of mice.

J Bacteriol, 1988 Jul, 170(7), 3243 - 8
Structure of the gene encoding phosphoribosylpyrophosphate synthetase (prsA) in Salmonella typhimurium; Bower SG et al.; The Salmonella typhimurium gene prsA, which encodes phosphoribosylpyrophosphate synthetase, has been cloned, and the nucleotide sequence has been determined . The amino acid sequence derived from the S . typhimurium gene is 99% identical to the derived Escherichia coli sequence and 47% identical to two rat isozyme sequences . Strains containing plasmid-borne prsA have been used to overproduce and purify the enzyme . The promoter for the S . typhimurium prsA gene was identified by deletion analysis and by similarity to the promoter for the E . coli prsA gene . The location of the prsA promoter results in a 416-base-pair 5' untranslated leader in the prsA transcript, which was shown by deletion to be necessary for maximal synthesis of phosphoribosylpyrophosphate synthetase . The S . typhimurium leader contains a 115-base-pair insert relative to the E . coli leader . The insert appears to have no functional significance.

J Bacteriol, 1988 Jul, 170(7), 3223 - 7
Expression of the divergent tricarboxylate transport operon (tctI) of Salmonella typhimurium; Widenhorn KA et al.; Membrane-associated gene products of shock-sensitive bacterial transport operons are often difficult to detect . A 4.5-kilobase DNA fragment, known to completely encode the Salmonella typhimurium tctI operon, was cloned in both orientations behind the T7 phage promoter phi 10 and expressed by using the T7 polymerase-promoter system of Tabor and Richardson (S . Tabor and C . C . Richardson, Proc . Natl . Acad . Sci . USA 82:1074-1078, 1985) . Under these conditions, five proteins were clearly demonstrated . One DNA strand was shown to encode the periplasmic (29,000-Mr) C protein (as a 31,000-Mr precursor), a 19,000-Mr protein, and a 40,000- to 45,000-Mr protein which ran as a diffuse band on sodium dodecyl sulfate-polyacrylamide gel electrophoresis . The opposite strand carried the information for two additional proteins of 29,000 and 14,000 Mr . By Tn5 mutagenesis, subcloning of Tn5 insertions, and subcloning of various deletion mutants it was shown that the tctI system is divergently transcribed . The periplasmic binding protein (C protein) is the first product of one operon, followed by the 19,000-Mr and 45,000-Mr integral inner membrane proteins . On the opposite strand only the 29,000-Mr protein was essential for tctI function, and it was found to be weakly attached to the inner membrane . Thus tctI encodes four proteins, one periplasmic, two integral, and one peripheral to the cytoplasmic membrane, with the genes arranged as tctA tctB tctC tctD.

J Bacteriol, 1988 Jul, 170(7), 3115 - 24
Molecular cloning and characterization of supQ/newD, a gene substitution system for the leuD gene of Salmonella typhimurium; Stover CK et al.; The isopropylmalate isomerase of Salmonella typhimurium and Escherichia coli is a complex of the leuC and leuD gene products . The supQ/new D gene substitution system in S . typhimurium restores leucine prototrophy to leuD mutants of S . typhimurium . Previous genetic evidence supports a model that indicates the replacement of the missing LeuD polypeptide by the newD gene product . This model proposed that this gene substitution is possible when a mutation at the supQ locus (near newD) liberates unaltered newD polypeptide from its normal complex with the supQ protein product . In this study, recombinant plasmids carrying newD, supQ, or both were transformed into E . coli and S . typhimurium strains deleted for the leuD and supQ genes to test the supQ/newD gene substitution model for suppression of leucine auxotrophy . It was determined that the newD gene encodes a 22-kilodalton polypeptide which can restore leucine prototrophy to leuD deletion strains and that a functional supQ gene prevents this suppression . It was also determined that the supQ and newD genes are separated by a gene encoding a 50-kilodalton protein, pB . While there is extensive DNA sequence homology between the leucine operons of S . typhimurium and E . coli, DNA hybridization experiments did not indicate substantial homology between the newD and leuD genes . These data, taken together with previously obtained genetic data, eliminate the possibility that supQ and newD are recently translocated segments of the leucine operon.

J Mol Biol, 1988 Jun 20, 201(4), 663 - 73
Structure and expression of the ompB operon, the regulatory locus for the outer membrane porin regulon in Salmonella typhimurium LT-2; Liljestrom P et al.; The ompB operon of Salmonella typhimurium encodes a positive transcriptional regulator OmpR and an inner membrane protein EnvZ . Both proteins are needed for the proper expression of the outer membrane proteins OmpC and OmpF . We have determined the nucleotide sequence of the ompB locus and its adjacent regions . A comparison between the S . typhimurium and Escherichia coli sequences revealed that the ompB locus is highly conserved . The sequence data also showed that ompR and envZ form an operon, where the coding regions overlap by four base-pairs . Utilizing ompR-lacZ and envZ-lacZ gene fusions, the translational levels of expression of these two genes were measured, showing that ompR is considerably more efficiently expressed than envZ . Analysis of ompR frameshift mutations showed that translation of envZ is almost totally dependent on the translation of the upstream gene ompR . The mechanism of this translational coupling appears to be a reinitiation of the ribosome at the overlapping region of the two genes . The characteristics of the OmpR and EnvZ proteins were in agreement with the known functions and cellular locations of these proteins . OmpR was found to contain a putative DNA binding site, while EnvZ contained two hydrophobic stretches typical of transmembrane regions . Both OmpR and EnvZ show extensive homologies with many proteins from a number of different origins, all of which function in pairs and through which environmental signals modulate gene expression . Hence, the tightly coupled synthesis of these proteins seems to be essential in eliciting a proper response in the transmembrane regulation of gene expression.

Sci Total Environ, 1988 Jun 15, 72, 1 - 9
Isolation of dinitropyrene in emission gas from a municipal incinerator and its formation by a photochemical reaction; Kamiya A et al.; In a previous paper, direct-acting mutagenicity was reported in emission gas from incomplete municipal incineration using Salmonella typhimurium TA-98 and TA-100 . This paper reports the detection of dinitropyrene (DNP) as a direct-acting mutagen using nitrogen selective gas chromatography . The gas-phase photochemical reaction of pyrene with nitrogen dioxide was examined in a quartz vessel with various reaction times and temperatures . 1-Nitropyrene (1-NP) was readily formed from pyrene in the absence of light irradiation and at low temperature, but DNP was not formed under similar conditions . DNP formation was catalyzed by nitric acid . The formation of DNP is dependent on light irradiation, temperature and HNO3 as catalyst . In a combustion source these factors affect the formation of DNP.

J Bacteriol, 1988 Jun, 170(6), 2884 - 5
Aerobic excretion of 1,2-propanediol by Salmonella typhimurium; Baldoma L et al.; Salmonella typhimurium excreted the rhamnose fermentation product 1,2-propanediol not only under anaerobic conditions, but also under aerobic conditions . The absence of an aldehyde dehydrogenase enzymatic activity that oxidizes to lactate the lactaldehyde formed in the dissimilation of rhamnose raised the intracellular concentration of the aldehyde which was alternatively reduced to the excretable 1,2-propanediol by a residual propanediol oxidoreductase activity.

J Bacteriol, 1988 Jun, 170(6), 2698 - 704
Identification of a site of ATP requirement for signal processing in bacterial chemotaxis; Smith JM et al.; In Escherichia coli and Salmonella typhimurium, ATP is required for chemotaxis and for a normal probability of clockwise rotation of the flagellar motors, in addition to the requirement for S-adenosylmethionine (J . Shioi, R . J . Galloway, M . Niwano, R . E . Chinnock, and B . L . Taylor, J . Biol . Chem . 257:7969-7975, 1982) . The site of the ATP requirement was investigated . The times required for S . typhimurium ST23 (hisF) to adapt to a step increase in serine, phenol, or benzoate were similar in cells depleted of ATP and in cells with normal levels of ATP . This established that ATP was not required for the chemotactic signal to cross the inner membrane or for adaptation to the transmembrane signal to occur . Depletion of ATP did not affect the probability of clockwise rotation in E . coli cheYZ scy strains that were defective in the cheY and cheZ genes and had a partially compensating mutation in the motor switch . Strain HCB326 (cheAWRBYZ tar tap tsr trg::Tn10), which was deficient in all chemotaxis components except the switch and motor, was transformed with the pCK63 plasmid (ptac-cheY+) . Induction of cheY in the transformant increased the frequency of clockwise rotation, but except at the highest levels of CheY overproduction, clockwise rotation was abolished by depleting ATP . It is proposed that the CheY protein is normally in an inactive form and that ATP is required for formation of an active CheY* protein that binds to the switch on the flagellar motors and initiates clockwise rotation . Depletion of ATP partially inhibits feedback regulation of the cheB product, protein methylesterase, but this may reflect a second site of ATP action in chemotaxis.

Infect Immun, 1988 Jun, 56(6), 1589 - 92
Lipopolysaccharide structure determines ionic and hydrophobic binding of a cationic antimicrobial neutrophil granule protein; Farley MM et al.; Bactericidal activity and binding of a 57,000-dalton cationic antimicrobial neutrophil granule protein (CAP57) are determined by the presence on bacteria of O-antigen polysaccharide chains and the availability of negatively charged groups in the lipid A region, the inner core region, or both regions of lipopolysaccharide . Polymyxin B (PMB)-resistant mutants with well-defined alterations in lipid A structure and charge (pmrA) are also more resistant to CAP57 . We used biologically active radioiodinated CAP57 to study the characteristics and kinetics of binding to a sensitive Rb lipopolysaccharide chemotype, Salmonella typhimurium SH9178, and the relatively resistant pmrA mutant strain SH7426 . Binding occurred rapidly and was specific and saturable . Because CAP57 appears to be bound in a manner similar to that of PMB, competition binding studies were performed . Excess PMB did compete with CAP57 for binding to SH9178 . Nonapeptide, a polycationic derivative of PMB that has lost its hydrophobic portions, demonstrated a marked decrease in ability to compete for binding with CAP57 compared with PMB . This demonstrated the importance of hydrophobic binding in the interaction of CAP57 with the microbial surface . Thus, we have shown that binding of CAP57 to SH9178 is specific, saturable, and similar to binding of PMB . Both hydrophobic and ionic properties of CAP57 appear to be necessary for binding.

Carcinogenesis, 1988 Jun, 9(6), 951 - 8
Microsomal metabolism of 1-nitrobenzo{e}pyrene to a highly mutagenic K-region dihydrodiol; Fu PP et al.; Aerobic metabolism of 1-nitrobenzo{e}pyrene (1-nitro-BeP) by rat liver microsomes produced 1-nitro-BeP trans-4,5-dihydrodiol, 6-hydroxy-1-nitro-BeP, and 8-hydroxy-1-nitro-BeP . When 3,3,3-trichloropropylene 1,2-oxide was incorporated into the metabolism, 1-nitro-BeP 4,5-oxide was the predominant metabolite, and 1-nitro-BeP trans-4,5-dihydrodiol was not detected . All of the metabolites were purified by both reversed- and normal-phase HPLC and characterized by analysis of their mass and 500 MHz proton NMR spectral data . 1-Nitro-BeP was not metabolized under hypoxic conditions . 1-Nitro-BeP and its four metabolites were assayed in Salmonella typhimurium tester strains TA98, TA98NR and TA98/1,8-DNP6, both in the presence and absence of S9 activation . As predicted, 1-nitro-BeP was a weak mutagen without S9 (2 revertants/micrograms in TA98); the addition of S9 resulted in approximately 18, 17 and 4 revertants/micrograms in TA98, TA98NR and TA98/1,8-DNP6 respectively . The two phenolic metabolites were mutagenic both in the presence and absence of S9, producing moderate responses (19-84 revertants/micrograms) . In addition, while the 1-nitro-BeP 4,5-oxide was only weakly mutagenic in TA98 (6-14 revertants/micrograms), 1-nitro-BeP trans-4,5-dihydrodiol was unexpectedly potent (approximately 300 revertants/micrograms both with and without S9) . These results indicate that microsomal epoxidation of 1-nitro-BeP followed by epoxide hydrolase-catalyzed hydrolysis of the resulting epoxide to the 1-nitro-BeP trans-4,5-dihydrodiol results in the most potent mutagenic derivatives . The weak mutagenicity of 1-nitro-BeP 4,5-oxide demonstrates that not all epoxides of nitrated polycyclic aromatic hydrocarbons (PAHs) are more mutagenic than the corresponding parent nitro-PAHs . Also, the lower S9-mediated mutagenicity of 1-nitro-BeP in TA98/1,8-DNP6 compared with TA98 indicates that the mutagenicity of 1-nitro-BeP is dependent upon nitroreduction and transesterification . Finally, we previously hypothesized that nitrated PAHs with their nitro substituents perpendicular or nearly perpendicular to the aromatic rings are very weak or nondirect-acting mutagens in Salmonella typhimurium tester strains . The results reported in this communication demonstrate that ring-oxidized derivatives of nitro-PAHs do not always follow this structure--mutagenicity correlation.

Carcinogenesis, 1988 Jun, 9(6), 907 - 10
Mutagenicity of hexachloro-1,3-butadiene and its S-conjugates in the Ames test--role of activation by the mercapturic acid pathway in its nephrocarcinogenicity; Vamvakas S et al.; The mutagenicity of hexachloro-1,3-butadiene and its S-conjugates 1-(glutathion-S-yl)-1,2,3,4,4-pentachloro-1,3-butadiene (GTB), 1,4-(bis-glutathion-S-yl-1,2,3,4-tetrachloro-1,3-butadiene (BGTB) and 1,4-(bis-cystein-S-yl)-1,2,3,4-tetrachloro-1,3-butadiene (BCTB) was investigated in Salmonella typhimurium TA100 using a modified preincubation assay . GTB was a direct-acting mutagen; the mutagenic potency of GTB was markedly enhanced by rat kidney microsomes or mitochondria and less so by cytosol . The bis-conjugates BGTB and BCTB were not mutagenic in the strains TA100, TA2638 and TA98 . Purified HCBD was not mutagenic either without exogenous metabolic activation or with rat liver microsomes fortified with NADPH . Preincubation with rat liver microsomes and glutathione resulted in an unequivocal mutagenic activity of HCBD which was increased by additional inclusion of rat kidney microsomes . The cysteine conjugate beta-lyase inhibitor aminooxyacetic acid decreased the mutagenicity of HCBD and its S-conjugates . These results provide strong evidence that formation of the corresponding monoglutathione S-conjugate from HCBD and subsequent cleavage of this conjugate by gamma-glutamyltranspeptidase and beta-lyase may be responsible for the nephrocarcinogenicity of the parent compound in vivo, whereas formation of the bis-glutathione S-conjugate probably plays no role in the organ specific effects of HCBD.

Carcinogenesis, 1988 Jun, 9(6), 1001 - 5
The effect of pyrazole, phenobarbital, ethanol and 3-methylcholanthrene pretreatment on the in vivo and in vitro genotoxicity of N-nitrosopyrrolidine; Gold B et al.; The in vitro genotoxicity of N-nitrosopyrrolidine (NPy) has been studied in Salmonella typhimurium strain TA1535 in the presence of untreated and pyrazole-, phenobarbital (PB)-, 4-day ethanol (EtOH)-, 10-day EtOH- and 3-methylcholanthrene (3-MC)-pretreated male Sprague-Dawley rat liver S-9 fractions . Unless stated otherwise, the last pretreatment exposure was 24 h prior to sacrifice and isolation of hepatic enzymes . Pyrazole and EtOH (10-day exposure) both effectively induced the conversion of NPy into a mutagen at doses as low as 500 microM . PB and EtOH (4-day exposure) had a modest enhancing effect on the number of revertants scored, while 3-MC and uninduced S-9 fractions gave results not significantly different from background (no NPy) . The same pretreatment protocols were used to determine the in vivo genotoxicity of NPy in rat liver using the technique of alkaline elution . The inducing agents had the exact opposite effect in vivo with control, 3-MC- and 4-day EtOH-treated animals showing the highest level of DNA damage . Pyrazole and 10-day EtOH pretreatments gave DNA elution rate constants comparable to animals not treated with NPy . However, in 10-day EtOH-pretreated animals which were administered NPy without a 24-h interval between EtOH and NPy exposure, DNA damage was observed at the same high levels as was seen in uninduced and 3-MC treated rats . The results are discussed in terms of a detoxification role for microsomal proteins and that the observed in vivo DNA damage may be induced by enzymes associated with the nuclear compartment.

Cell Biol Toxicol, 1988 Jun, 4(2), 173 - 86
The lack of genotoxicity of sodium fluoride in a battery of cellular tests; Tong CC et al.; In a comprehensive assessment of genotoxicity, sodium fluoride was evaluated in a battery of cellular tests providing different genetic end points and biotransformation capabilities . The tests included the following: rat hepatocyte primary culture/DNA repair assay, Salmonella typhimurium histidine locus reversion assay, adult rat liver epithelial cell/hypoxanthine guanine phosphoribosyl transferase mutation assay, and sister chromatid exchange in two target cell types, human peripheral blood lymphocytes and Chinese hamster ovary cells . Negative findings were made in all assays, indicating that sodium fluoride is not genotoxic in these assays.

Anticancer Drug Des, 1988 Jun, 3(1), 67 - 76
Microbial mutagenicity of chlorambucil, its half-mustard and mitomycin C: a modified screening strategy for genetic toxicology of bis-alkylating anti-tumour drugs; Ferguson LR et al.; Early assessment of the genetic toxicology of anti-tumour drugs often employs microbial assays, particularly a group of specially developed Salmonella typhimurium strains (uvrB-) which are DNA repair-deficient due to a defective uvrB gene . While such strains are more sensitive than the wild-type to the mutagenic effects of many classes of compound, the DNA cross-linking agent chlorambucil (which is a known human carcinogen) has been shown to be toxic but non-mutagenic in this assay . The mutagenic activities of chlorambucil, its half-mustard analogue and another cross-linking agent (mitomycin C) were thus evaluated in a DNA-proficient strain of the yeast Saccharomyces cerevisiae and also in two isogenic sets of four S . typhimurium strains differing in uvrB gene and plasmid pKM101 presence . In yeast, all three compounds were effective mutagens and recombinogens, while in bacteria the two cross-linking agents were significantly mutagenic in the uvrB+ (DNA repair-proficient) but not in the uvrB- strains . By comparison, the half-mustard was mutagenic in both the uvrB- and uvrB+ strains . This work suggests that it is unwise to rely on results from the commonly used S . typhimurium bacterial strains for evaluating the mutagenicity of DNA cross-linking agents destined as clinical anti-tumour drugs . The use of yeast plus at least one of the sets of four strains employed in this study would provide information more directly relevant to mammalian cells, which are DNA repair-proficient . In addition, a comparison of the patterns of bacterial mutagenicity and toxicity provides evidence for the mode of action (DNA cross-linking or monoadduct formation) of compounds within a series.

Int J Food Microbiol, 1988 Jun, 6(4), 309 - 16
The survival and recovery of Salmonella typhimurium phage type U285 in frozen meats and tryptone soya yeast extract broth; Barrell RA; The survival of S . typhimurium U285 was studied in cooked minced beef, sausage mixture and tryptone soya yeast extract (TSY) broth stored at freezer temperatures (-18 degrees C to -20 degrees C) for up to 10 weeks . Survival, as indicated by changes in viable counts, was best in minced beef followed by sausage mixture and TSY broth . Metabolic injury was minimal in each substrate whereas structural injury was detected, especially in TSY broth . Recovery, as indicated by changes in viable counts during thawing at room temperature, was generally complete after thawing 10 g or 10 ml amounts for 2 h . Viable counts obtained after thawing at refrigerator temperature for 24 h were similar to those obtained after 2h at room temperature . For specimens containing low inocula of salmonellae (0.5 cells/g), more isolations were obtained with pre-enrichment than with direct enrichment for minced beef and sausage mixture.

Biomed Environ Sci, 1988 Jun, 1(1), 83 - 9
A preliminary study of the changes in the direct-acting mutagenicities of several nitropolycyclic aromatic hydrocarbons after exposure under sunlight; Xu XB et al.; Five commercially available nitropolyclyclic aromatic hydrocarbons (nitro-PAH), namely, 4-nitrobiphenyl, 2-nitrofluorene, 9-nitroanthracene, 1-nitropyrene, and 2,7-dinitrofluorene, were exposed under restricted sunlight in the open air . The direct-acting mutagenicities of the samples after an exposure of 45 days were measured in order to compare them with those of the original samples in the Ames Salmonella typhimurium bioassay . It was found that the mutagenicities of some nitro-PAH do not change significantly while the mutagenicities of others increase or decrease after exposure . A preliminary study of nitro-PAH reaction products after exposure using GC, GC/MS, and FT-IR is also reported.

Cell Biol Toxicol, 1988 Jun, 4(2), 225 - 39
The genotoxicity of lucidin, a natural component of Rubia tinctorum L., and lucidinethylether, a component of ethanolic Rubia extracts; Westendorf J et al.; The genotoxic activity of lucidin (1,3-dihydroxy-2-hydroxymethyl-9,10-anthraquinone), a natural component of Rubia tinctorum L., was tested in a battery of short-term tests . The compound was mutagenic in five Salmonella typhimurium strains without metabolic activation, but the mutagenicity was increased after addition of rat liver S9 mix . In V79 cells, lucidin was mutagenic at the hypoxanthine-guanine phosphoribosyl transferase gene locus and active at inducing DNA single-strand breaks and DNA-protein cross-links as assayed by the alkaline elution method . Lucidin also induced DNA repair synthesis in primary rat hepatocytes and transformed C3H/M2-mouse fibroblasts in culture . We also investigated lucidinethylether, which is formed from lucidin by extraction of madder roots with boiling ethanol . This compound was also mutagenic in Salmonella, but only after addition of rat liver S9 mix . Lucidinethylether was weakly mutagenic to V79 cells which were cocultivated with rat hepatocytes . The compound did not induce DNA repair synthesis in hepatocytes from untreated rats, but positive results were obtained when hepatocytes from rats pretreated with phenobarbital were used . We conclude that lucidin and its derivatives are genotoxic.

J Gen Microbiol, 1988 Jun, 134 ( Pt 6), 1737 - 46
Molecular cloning, physical mapping and expression of the bet genes governing the osmoregulatory choline-glycine betaine pathway of Escherichia coli; Andresen PA et al.; An analysis of the bet genes governing the osmoregulatory choline-glycine betaine pathway of Escherichia coli was performed . A 9 kb BamHI fragment, located 30 to 39 kb counterclockwise of the EcoRI site of lacZ, coded for all known Bet activities . The following genes were identified: the betA gene for the choline dehydrogenase, the betB gene for the betaine aldehyde dehydrogenase, and the betT gene or operon for the high-affinity choline transport . The betB and the betT genes were named in this paper, and the clockwise gene order was shown to be betA,B,T . Subcloning gave plasmids which expressed each of the three Bet activities separately . The cloned bet genes remained osmotically regulated, indicating the existence of several osmotically regulated promoters in the bet region . Salmonella typhimurium, which carried the bet region of E . coli in the broad-host-range vector pRK293 expressed the three Bet activities and displayed increased osmotic tolerance in the presence of choline.

Mol Gen Mikrobiol Virusol, 1988 Jun, (6), 37 - 43
{Cloning and expression of the histidine operon of Salmonella typhimurium in cells of Escherichia coli}; Lisenkov AF et al.; The histidine operon of Salmonella typhimurium and its fragments were cloned in Escherichia coli cells on a multicopy plasmid . Expression of the cloned genes and histidine production by the variants possessing the hisG mutation which desensibilizes the ATP phosphoribosyl transferase for histidine were studied . Amplification of the complete operon including the hisG gene enables histidine accumulation of 2-3 g/l after 72 hours of fermentation.

J Toxicol Sci, 1988 Jun, 13 Suppl 1, 245 - 56
Mutagenicity test of cefodizime sodium; Ohuchida A et al.; The mutagenicity of cefodizime sodium (THR-221) was investigated by the reverse mutation test using seven bacterial strains (Salmonella typhimurium strains TA100, TA98, TA1535, TA1537 and TA1538, and Escherichia coli strains WP2 and WP2uvrA) and the chromosomal aberration test with cultured Chinese hamster lung (CHL) cells . The reverse mutation test was carried out in dose range from 0.0025 to 5.0 micrograms/plate in the absence and presence of mammalian metabolic activation system . Antibacterial effects were observed at concentrations more than 0.25 microgram/plate, and no significant increases in the number of revertants were observed at the dose levels where antibacterial effects were not detected . THR-221 caused no increases in the number of chromosomal aberrants at dose levels of 0.75, 1.5, 3.0 and 6.0 mg/ml in the absence and presence of the metabolic activation . These results indicate that THR-221 has no mutagenic activity.

EMBO J, 1988 Jun, 7(6), 1863 - 9
DNA supercoiling and the leu-500 promoter mutation of Salmonella typhimurium; Richardson SM et al.; DNA supercoiling is an important, but relatively poorly understood factor which influences promoter function . leu-500 is a point mutation in the promoter of the leucine operon of Salmonella typhimurium which confers leucine auxotrophy . It can be phenotypically suppressed by mutations in the topA gene, which encodes topoisomerase I, implicating DNA supercoiling in the regulation of this promoter . We have demonstrated that phenotypic suppression of this mutant promoter is transcriptional, and that topA mutations restore function to the mutant promoter . Transcription from the leu-500 promoter was examined in a series of strains harbouring topA and tos (presumptive gyr) mutations, each of which exhibits a different level of in vivo plasmid supercoiling . Promoter function did not correlate with the level of supercoiling but rather with the presence or absence of a functional topA gene . Furthermore, when cloned onto a multicopy plasmid, the leu-500 promoter failed to function, even in a topA background . Thus, local rather than global changes in DNA topology are implicated in the activation of this promoter.

Biochimie, 1988 Jun, 70(6), 757 - 68
A degradation pathway of propionate in Salmonella typhimurium LT-2; Fernandez-Briera A et al.; Salmonella typhimurium LT-2 can utilize propionate as its sole carbon source . Studies on growth, oxidation by resting cell suspensions and by permeabilized cells, suggest that the propionate is transported by the acetate system . This result was confirmed using labeled propionate and acetate . ATP-monocarboxylate phosphotransferase, acyl-CoA orthophosphate acyl-transferase, propionyl-CoA dehydrogenase, acrylyl-CoA hydratase, lactate dehydrogenase, phosphoenolpyruvate (PEP) synthase and PEP-carboxylase activities have been identified in extracts of cells grown on propionate . Mutants deficient in PEP-carboxylase and synthase are unable to utilize propionate . On the basis of results obtained, it seems that the propionate degradation pathway occurs via acrylate and that PEP-synthase and PEP-carboxylase are essential enzymes.

Appl Environ Microbiol, 1988 Jun, 54(6), 1591 - 4
Plasmid profile analysis of a salmonellosis outbreak and identification of a restriction and modification system; Whiley SJ et al.; After an outbreak of salmonellosis in humans caused by Salmonella typhimurium bacteriophage type 135, 62 isolates from human, animal, and water sources were retained for further analysis . Most of the isolates (92%) could be placed in one of five plasmid pattern groups, with a majority containing a common 60-kilobase plasmid and a smaller 3.8-kilobase-pair plasmid . This small plasmid, pIMVS1, was labeled with {32P}phosphate and used as a probe in subsequent colony and Southern hybridization studies . We concluded that pIMVS1 from isolates obtained from humans was genetically different from plasmids of a similar size found in isolates from chickens . Studies to characterize pIMVS1 were undertaken to determine if it codes for known virulence factors . It did not appear to be associated with the formation of attachment pili or major outer membrane proteins . By using transposon mutagenesis techniques, Tn3(Apr) was inserted into pIMVS1, and the existence of a restriction and modification system was deduced.

Biotechnol Appl Biochem, 1988 Jun, 10(3), 273 - 86
Biochemical and immunochemical analysis of gangliosides of human small cell lung carcinoma: production of monoclonal antibodies against a unique marker of small cell lung carcinoma, ganglioside Fuc GM1; Fuchs BB et al.; Immunization of mice with a pure preparation of the ganglioside adsorbed on Salmonella typhimurium and hybridization of splenocytes with myeloma P3-X63-Ag 8.653 have resulted in hybridomas producing monoclonal antibodies against ganglioside Fuc GM1, a marker of human small cell lung carcinoma . Characterization of four hybridomal clones and data on the antigenic specificity of the monoclonal antibodies are given . All four monoclonal antibodies reacted only with Fuc GM1 in an enzyme-linked immunosorbent assay . In radioimmunodetection of the antigen on thin-layer plates, two of the four monoclonal antibodies gave cross-reactions with Fuc GD1b . The obtained monoclonal antibodies have revealed the presence of Fuc GM1 in all seven cases of small cell lung carcinoma we have studied and the absence of Fuc GM1 in the normal human lung tissue and in lung adenocarcinomas.

J Bacteriol, 1988 Jun, 170(6), 2816 - 26
DNA supercoiling and the anaerobic and growth phase regulation of tonB gene expression; Dorman CJ et al.; We show that several interacting environmental factors influence the topology of intracellular DNA . Negative supercoiling of DNA in vivo is increased by anaerobic growth and is also influenced by growth phase . The tonB promoter of Escherichia coli and Salmonella typhimurium was found to be highly sensitive to changes in DNA supercoiling . Expression was increased by novobiocin, an inhibitor of DNA gyrase, and was decreased by factors which increase DNA superhelicity . Expression of the plasmid-encoded tonB gene was enhanced by gamma delta insertions in cis in a distance- and orientation-independent fashion . Both the res site and the TnpR protein of gamma delta, which is known to function as a type I topoisomerase, were required for this activation . tonB expression increased during the growth cycle and was reduced by anaerobiosis . There was excellent correlation between tonB expression from a plasmid and the level of supercoiling of that plasmid under a wide range of conditions . The chromosomal tonB gene was regulated in a manner identical to that of the plasmid-encoded gene . Thus, the physiological regulation of tonB expression in response to anaerobiosis and growth phase appears to be mediated by environmentally induced changes in DNA superhelicity.

J Bacteriol, 1988 Jun, 170(6), 2668 - 75
Sequence of the dnaB gene of Salmonella typhimurium; Wong A et al.; The dnaB gene of Escherichia coli encodes a helicase that operates at replication forks of the bacterium and certain of its bacteriophages to produce separated strands suitable for subsequent use by primase and DNA polymerase III . Here, we present the sequence of the dnaB gene of Salmonella typhimurium, a functionally interchangeable analog of the E . coli dnaB gene . The DnaB proteins of these two organisms, inferred from the DNA sequences, are identical in length and in 93% of amino acid residues . Extended portions of the DnaB proteins are also similar to two phage-encoded DNA replication proteins: the gene 4 helicase-primase of coliphage T7 and, as reported previously (H . Backhaus and J . B . Petri, Gene 32: 289-303, 1984), the gene 12 protein of Salmonella phage P22 . In contrast, little similarity was found between DnaB and either the UvrD repair helicase or transcription termination factor Rho (an RNA-DNA helicase) . These results identify S . typhimurium DnaB as a member of the DnaB family of proteins by structural, as well as functional, criteria and provide the basis for the eventual identification, by mutational studies, of residues in DnaB critical for its function.

Infect Immun, 1988 Jun, 56(6), 1436 - 41
Natural killer cell activation and interferon production by peripheral blood lymphocytes after exposure to bacteria; Klimpel GR et al.; We have previously shown that peripheral blood natural killer (NK) cells have significant levels of cytotoxic activity against Shigella flexneri-infected HeLa cells . In this report, we show that NK cell activity against K562 tumor cells and Shigella flexneri-infected HeLa cells can be greatly enhanced by preincubating peripheral blood lymphocytes (PBL) for 18 h with kanamycin-treated Shigella flexneri or Salmonella typhimurium . Cell-free supernatants obtained from PBL-bacteria cultures contained high levels of interferon (IFN) activity, which was characterized as a mixture of IFN-gamma and IFN-alpha . Cytotoxic activity associated with PBL precultured with shigellae was associated with predominantly CD16+ (Leu-11+) and CD2+ (OKT-11+) cells . Further, IFN production was dependent upon the presence of CD16+ and CD2+ cells at culture initiation . Enhancement of cytotoxic activity associated with PBL-bacteria cultures did not, however, appear to be dependent upon IFN production, since low numbers of bacteria which failed to stimulate IFN production induced high levels of NK cell activity . Lipopolysaccharide appeared not to be involved in bacteria-induced IFN production or enhanced NK cell activity, since Salmonella lipopolysaccharide failed to induce IFN production or enhance NK cell activity . These results suggest that IFN production by NK cells and the killing of bacteria-infected cells play an important role in host defense against facultative intracellular bacterial infections.

Biochemistry, 1988 May 17, 27(10), 3709 - 14
ATP-dependent inactivation and slow binding inhibition of Salmonella typhimurium D-alanine:D-alanine ligase (ADP) by (aminoalkyl)phosphinate and aminophosphonate analogues of D-alanine; Duncan K et al.; In Salmonella typhimurium, D-alanine:D-alanine ligase (ADP) (EC 6.3.2.4) is the second enzyme in the three enzyme D-alanine branch pathway of peptidoglycan biosynthesis . The interaction of this enzyme with a possible transition-state analogue, the (aminoalkyl)phosphinate D-3-{(1-aminoethyl)phosphinyl}-2-heptylpropionic acid {Parsons et al . (1987) Abstracts of Papers, 193rd National Meeting of the American Chemical Society, Denver, CO, MEDI 63, American Chemical Society, Washington, DC}, has been studied . This compound is a potent active site directed inhibitor and is competitive with D-alanine (Ki = 1.2 microM); it exhibits time-dependent inhibition in the presence of ATP . Kinetic analysis revealed a rapid onset of steady-state inhibition (kon = 1.35 X 10(4) M-1 s-1) followed by slow dissociation of inhibitory complex(es) with a half-life of 8.2 h . The inhibitory complex was shown to consist of E...I...ATP in equilibrium with E...I, Pi, and ADP . Similar time-dependent inhibition was also observed with D-(1-aminoethyl)phosphonic acid (D-Ala-P) (Ki = 0.5 mM; kon = 27 M-1 s-1; t1/2 for regain = 1.73 min) but not with D-(1-aminoethyl)phosphinic acid, which behaved as a simple competitive inhibitor (Ki = 0.4 mM) . The mechanism of inhibition is discussed in the light of the precedents of glutamine synthase inhibition by methionine sulfoximine and phosphinothricin.

Biochemistry, 1988 May 17, 27(10), 3701 - 8
Isolation, cloning, and sequencing of the Salmonella typhimurium ddlA gene with purification and characterization of its product, D-alanine:D-alanine ligase (ADP forming); Daub E et al.; A gene coding for D-alanine:D-alanine (D-Ala-D-Ala) ligase (ADP forming) (EC 6.3.2.4) activity has been isolated from a lambda library of Salmonella typhimurium DNA . Insertion mutations in the gene indicate that the gene is not essential for growth of the bacterium . The encoded enzyme was purified from an overproducing strain of S . typhimurium . D-Ala-D-Ala ligase is a protein of 39,271 molecular weight and has a kcat of 644 min-1 at pH 7.2 . A 2.4-kilobase SalI-SphI fragment containing the gene was sequenced, and the ddlA gene consists of 1092 nucleotides . The gene sequence was compared to the sequence of the ddl gene of Escherichia coli {Robinson, A . C., Kenan, D . J., Sweeney, J., & Donachie, W . D . (1986) J . Bacteriol . 167, 809-817} . Because of differences between the S . typhimurium gene and the E . coli ddl gene, the S . typhimurium gene has been named ddlA.

Experientia, 1988 May 15, 44(5), 447 - 9
Analysis of structural features responsible for the sweetness of the sesquiterpene, hernandulcin; Compadre CM et al.; The relationship between sweetness and structure was studied for several analogues of the intensely sweet sesquiterpene, hernandulcin . These derivatives were prepared synthetically, and were spectroscopic and conformational analysis . With the exception of the parent substance, none of the derivatives tested proved to be sweet . Evidence gathered in this study suggests that hernandulcin binds to its putative receptor through a three-point interaction, involving the C-1 carbonyl and C-1' hydroxyl groups, and the double bond between C-4' and C-5' . In the course of a preliminary safety assessment, the 3-desmethyl derivative of hernandulcin was found to be mutagenic toward Salmonella typhimurium strain TM677.

Cancer Res, 1988 May 15, 48(10), 2740 - 3
Inhibition of beta-propiolactone-induced neoplasia of the forestomach and large bowel by 4-mercaptobenzene sulfonate in mice and rats; Hochalter JB et al.; Studies have been initiated to find compounds that can trap direct-acting carcinogens within the lumen of the gastrointestinal tract and thus prevent these carcinogens from attacking tissues of the host . Sodium 4-mercaptobenzene sulfonate (4-MBSNa) is a potent nucleophile and was found to react rapidly in vitro with the direct-acting carcinogen beta-propiolactone (BPL) . In further investigations 4-MBSNa was shown to inhibit mutagenesis resulting from exposure of Salmonella typhimurium strain TA-100 to BPL and a second direct-acting carcinogen, N-methyl-N'-nitro-N-nitrosoguanidine . Subsequent experiments were performed to determine if 4-MBSNa would inhibit BPL-induced carcinogenesis in vivo . In the first of these, 4-MBSNa was administered by p.o . intubation to female A/J mice 5 min before p.o . administration of BPL . Under these conditions inhibition of carcinogenesis of the forestomach occurred . In a second experiment, 4-MBSNa was given by rectal intubation 5 min before BPL also administered intrarectally . Administration of BPL intrarectally produced adenomatous polyps of the large intestine . The occurrence of these neoplasms was inhibited by the prior administration of 4-MBSNa . The data presented show that 4-MBSNa has the capacity to trap direct-acting carcinogens and to inhibit the occurrence of BPL-induced neoplasia.

J Biol Chem, 1988 May 5, 263(13), 6268 - 75
Site-directed cross-linking . Establishing the dimeric structure of the aspartate receptor of bacterial chemotaxis; Milligan DL et al.; Cysteine residues introduced at specific locations in the aspartate receptor of Salmonella typhimurium provide anchor points for cross-linking and serve as chemical markers for structural studies of this oligomeric receptor . These markers have been used to measure the rate of subunit exchange between oligomeric receptors and to show that ligand binding inhibits this exchange . The cysteine-containing receptors can be oxidatively cross-linked to completion within the oligomeric receptor, indicating that the receptor has an even number of subunits . Based on this observation, a technique has been developed that can be used to determine the oligomeric structure of proteins under a variety of experimental conditions . The technique involves the measurement of the effect of dilution by "cysteineless" receptor subunits on cross-linking and reveals that the aspartate receptor is dimeric in detergent solution, in a mixed-micelle system, and in reconstituted membrane vesicles . Binding of aspartate does not change the oligomeric structure of the receptor, indicating that transmembrane signaling occurs within an oligomeric receptor of constant size.

Carcinogenesis, 1988 May, 9(5), 869 - 71
Synthesis of 2-azido-3-methylimidazo{4,5-f}quinoline and photolytic generation of a highly reactive and mutagenic IQ derivative; Wild D et al.; Azido-IQ (2-azido-3-methylimidazo{4,5-f}quinoline), a novel analog of the food mutagen and carcinogen IQ (2-amino-3-methylimidazo{4,5-f}quinoline) was synthesized and characterized . Both thermolysis and photolysis of this azide yield a short-lived nitrene which can react as an electrophile either directly or via protonation to a nitrenium ion . Reaction of the nitrene/nitrenium ion with water produces N-hydroxy-IQ; reactions with nucleotides and with DNA (in vitro and in cells) produce adducts efficiently . Correspondingly, high frequencies of mutations are induced in Salmonella typhimurium by photolyzed azido-IQ . Comparative mutation assays with the S . typhimurium strains TA98 and the hydroxylamine-resistant TA98/1,8-DNP6 provide evidence for a novel mechanism of mutation, direct reaction of the nitrene or nitrene-derived nitrenium ion with DNA without involvement of the hydroxylamine . The photolysis of arylazides promises to be a very convenient and generally applicable non-enzymatic procedure for the cell-free or intracellular generation of short-lived and highly reactive electrophilic species which are assumed to be identical with the metabolically formed ultimate mutagens/carcinogens of arylamines and nitroarenes.

J Antibiot (Tokyo), 1988 May, 41(5), 648 - 54
Terpentecin, an inhibitor of DNA synthesis; Tamamura T et al.; Terpentecin at a concentration of 0.78 microgram/ml decreased the number of viable cells of Escherichia coli NIHJ to less than one thousandth the starting number in an hour when added to an exponentially growing culture in a nutrient broth . During this time, the turbidity of the cell suspension kept increasing as fast as the control . Microscopic inspection of the cells exposed to terpentecin under these conditions revealed that the cells were elongated . Terpentecin at a concentration of 6.25 micrograms/ml inhibited incorporation of {14C}thymidine into the acid-insoluble material of cells of E . coli NIHJ by 70% in 30 minutes in contrast to little or no inhibition of the incorporation of {14C}uridine or {14C}leucine . Under similar conditions, terpentecin did not inhibit either membrane transport (uptake) of {14C}thymidine into the cells or the metabolic conversion of the precursor into various cellular acid-soluble components . Terpentecin at a higher concentration (70 micrograms/ml) inhibited by 40% in 30 minutes the incorporation of {methyl-3H}thymidine triphosphate into the DNA fraction of toluene-treated cells of E . coli JE6296 (pol A-) . Terpentecin showed stronger antibacterial activities against Bacillus subtilis M45T (rec-) and E . coli BE1121 (rec A-) than against their corresponding wild type strains . However, terpentecin showed no mutagenicity by the Ames test with Salmonella typhimurium strains TA100, TA98, TA92, TA1538, TA1537 and TA1535, and with E . coli WP2 (uvr A) . Terpentecin at a lower concentration (0.07 micrograms/ml) inhibited growth in vitro of mouse leukemia L1210 cells by 50% . With the mammalian cells again the incorporation of {14C}thymidine into the acid-insoluble cell material was inhibited more strongly than incorporation of {14C}uridine and {14C}leucine . There was no sign of mutagenicity by the micronucleus test using mice.

Mutat Res, 1988 May, 208(1), 39 - 44
Harman and norharman induce SOS responses and frameshift mutations in bacteria; Oda Y et al.; Norharman and harman, beta-carboline derivatives with comutagenic activity in Salmonella typhimurium, were examined for their activity to induce SOS responses in S . typhimurium using the umu-test and mutations in Escherichia coli . The inducibility of the umuC gene by norharman and harman was assayed by measuring the levels of beta-galactosidase activity in tester cells harbouring the umuC'-'lacZ fusion gene on a plasmid . In the umu-test, both norharman and harman weakly induced umuC gene expression at 25-100 and 50-150 micrograms/ml, respectively . In the mutation test using reversion from trpE9777 to Trp+, harman was relatively more potent than norharman in inducing the mutations . These results indicate that norharman and harman induce SOS responses as well as reversion of trpE9777 frameshift mutation in bacteria.

Mutat Res, 1988 May, 208(1), 33 - 8
The mutagenic activity of chlorpromazine; Obaseiki-Ebor EE et al.; The mutagenic activity of chlorpromazine hydrochloride based on the Ames plate incorporation test and the modified fluctuation test in the presence and absence of liver microsomal enzyme (S9 fraction) and NADPH was determined . The results indicated that chlorpromazine required activation for mutagenic activity for the reversion of some of the tester bacterial strains from tryptophan and histidine dependence to independence respectively . The positive response of Escherichia coli WP2 trp, uvrA, E . coli WP2 trp (pKM101 and pAQ1) and Salmonella typhimurium his TA102 indicated that chlorpromazine mediates base-pair substitution and frame-shift mutagenesis.

Mutat Res, 1988 May-Aug, 205(1-4), 79 - 90
Application of a cellular test battery in the decision point approach to carcinogen identification; Williams GM et al.; The assessment of the potential carcinogenicity of a chemical requires a systematic approach taking into account various types of data . Important information on the DNA reactivity and other genetic effects of chemicals can be obtained from a battery of cellular tests . A battery is described which includes DNA repair in hepatocytes, mutagenesis in Salmonella typhimurium, mutagenesis, chromosome alterations, and transformation in mammalian cells . The interpretation of findings in this battery for the identification of potential carcinogenicity of chemicals is discussed.

Mutat Res, 1988 May, 193(3), 269 - 73
Frameshift lesions induced by oxazolopyridocarbazoles are recognized by the mismatch repair system in Escherichia coli; Rene B et al.; The simple reversible intercalating agent isopropyl-OPC (iPr-OPC) induces frameshift-1 mutations in Salmonella typhimurium and Escherichia coli . The mutagenic responses of S . typhimurium and E . coli wild-type strains are not proportional to the amount of drug intercalated into double-stranded nucleic acids in living bacteria; it occurs only above a minimum level of binding . The fact that mismatch-repair-deficient (mutS) as well as adenine-methylation-deficient (dam) E . coli mutants are hypermutable at low concentrations of iPr-OPC suggests that the majority of mutants induced by this intercalating drug occur as mismatch-repairable mutations (or lesions) in the newly synthesized DNA strand close to the replication fork.

Mutat Res, 1988 May, 193(3), 219 - 27
pH induced damage and repair in E . coli; Musarrat J et al.; Escherichia coli lost its colony-forming ability when suspended in Tris/NaOH or Tris/Mg2+ buffers of pH 10.0 and 4.0, respectively . A significant decrease in the survival of radiation-sensitive mutants recA, polA, res, rer and lexA was observed as compared to their wild-type counterpart under these conditions . The alkali-injured cells were found to recover when incubated at 37 degrees C for 2 h in 0.05 M phosphate buffer of pH 8.0, whereas no such liquid holding recovery was observed in recA and lexA mutants . Recovery in phosphate buffer was not affected by metabolic inhibitors . As a result of alkali treatment, the sensitivity of bacteria to ultraviolet light (UV) was enhanced . However, on incubation for 2 h in recovery buffer at 37 degrees C, the bacteria regained partial UV resistance . Bacteria exposed to alkaline environment exhibited an enhanced level of mutagenesis . Contrary to the treated wild-type, the mutants recA and lexA did not exhibit any increase in the mutation frequency . Alkali treatment to GC----AT transition mutants of Salmonella typhimurium, TA102 and TA104 resulted in the highest number of revertants per plate.

J Immunol, 1988 May 1, 140(9), 3180 - 5
Host resistance to mucosal gram-negative infection . Susceptibility of lipopolysaccharide nonresponder mice; Eden CS et al.; The effect of Lps on the resistance of mice to gram-negative infection was compared in two genetically different backgrounds; C3H and C57BL . To mimic the natural sequence of pathogenetic events, infection was induced via a mucosal surface (intravesically), with Escherichia coli which remained at the mucosal site and Salmonella typhimurium which invaded to e.g., livers and spleens . Susceptibility was assessed as the bacterial persistence in kidneys, bladders, livers, and spleens at various times after infection . The initial clearance of both bacterial species from the mucosal site was significantly impaired in Lpsd mice both in the C3H and C57BL backgrounds . In the C57BL mice, additional unknown determinants conferred increased resistance to mucosal infection compared to the C3H mouse . For S . typhimurium, these resistance factors and alleles at the Lps locus dominated over Ity as determinants of resistance to mucosal infection . The Itys genotype conferred a significant increase in the susceptibility only to systemic infection, especially in the Lpsd, Itys mice . These results demonstrate an important difference between the genetic determinants of host resistance at mucosal and systemic sites, and emphasize the role of LPS induced host defense mechanisms for bacterial clearance from mucosal surfaces.

J Bacteriol, 1988 May, 170(5), 2374 - 8
Regulation of cytoplasmic proline levels in Salmonella typhimurium: effect of osmotic stress on synthesis, degradation, and cellular retention of proline; Csonka LN; I investigated the effects of osmotic stress on the synthesis and catabolism of proline in Salmonella typhimurium by measuring the intracellular and extracellular proline levels in various strains . In the wild-type strain, exposure to 0.8 M NaCl did not cause a significant change in the intracellular proline level; however, it brought about a 6.5-fold increase in the intracellular glutamate pool size . These results indicate that gamma-glutamyl kinase is inhibited by proline in wild-type cells in media of normal or elevated osmolarity . I also tested whether proline is subject to turnover in cells wild type with respect to the enzymes of the proline degradation pathway . In strains that were wild type for proline biosynthesis, the loss of the proline catabolic enzymes, due to putA mutations, did not result in a statistically significant increase in the intracellular proline levels . Therefore, in the wild-type strain, proline turnover does not seem to be important for control of the intracellular proline levels . However, in a proline-overproducing mutant, a putA lesion caused a threefold increase in the intracellular proline level and a 6.5-fold increase in the extracellular proline level, indicating that proline is subject to turnover in the overproducing mutant . The proline-overproducing mutants excreted large quantities of the proline into the culture medium; osmotic stress altered the partitioning of proline such that the ratio of intracellular to extracellular levels of proline increased with increased osmotic stress . The increased cellular retention of proline in media of high osmolarity is probably due to the functioning of the ProP and ProU proline transport systems, which are stimulated under conditions of osmotic stress.

J Bacteriol, 1988 May, 170(5), 2344 - 51
Near-UV stress in Salmonella typhimurium: 4-thiouridine in tRNA, ppGpp, and ApppGpp as components of an adaptive response; Kramer GF et al.; We have examined the role of 4-thiouridine in the responses of Salmonella typhimurium to near-UV irradiation . Mutants lacking 4-thiouridine (nuv) and mutants defective in the synthesis of ppGpp (guanosine 5'-diphosphate-3'-diphosphate) (relA) were found to be sensitive to killing by near-UV . Near-UV induced the synthesis of a set of proteins that were not induced in the nuv mutant . Some of these proteins were identified as oxidative defense proteins, and others were identified as ppGpp-inducible proteins . Over 100-fold increases in ApppGpp (adenosine 5', 5"'-triphosphoguanosine-3"'-diphosphate, the adenylylated form of ppGpp) were observed in wild-type cells after near-UV irradiation but not in the 4-thiouridine-deficient mutant . These data support a model in which ppGpp and ApppGpp, a dinucleotide proposed to be synthesized by tRNA-aminoacyl synthetases as a response to the cross-linking of 4-thiouridine in tRNA by near-UV, induce the synthesis of proteins necessary for resistance to near-UV irradiation.

J Bacteriol, 1988 May, 170(5), 2159 - 62
Anaerobic metabolism of the L-rhamnose fermentation product 1,2-propanediol in Salmonella typhimurium; Obradors N et al.; When grown anaerobically on L-rhamnose, Salmonella typhimurium excreted 1,2-propanediol as a fermentation product . Upon exhaustion of the methyl pentose, 1,2-propanediol was recaptured and further metabolized, provided the culture was kept under anaerobic conditions . n-Propanol and propionate were found in the medium as end products of this process at concentrations one-half that of 1,2-propanediol . As in Klebsiella pneumoniae (T . Toraya, S . Honda, and S . Fukui, J . Bacteriol . 139:39-47, 1979), a diol dehydratase which transforms 1,2-propanediol to propionaldehyde and the enzymes involved in a dismutation that converts propionaldehyde to n-propanol and propionate were induced in S . typhimurium cultures able to transform 1,2-propanediol anaerobically.

J Clin Lab Immunol, 1988 May, 26(1), 49 - 53
The limitation of the human neutrophil chemiluminescence response by extracellular peroxidase is stimulus dependent: effect of added horse radish peroxidase on the response induced by both soluble and particulate stimuli; Dahlgren C et al.; When polymorphonuclear leukocytes (PMNL) interact with soluble and particulate stimuli, the cells increase their production of oxidative metabolites . This increased production can be measured as luminol amplified light emission or chemiluminescence (CL) . The CL response of human PMNL has been investigated, and it was found that the formyl-methionyl-leucyl-phenylalanine (FMLP) and the phorbol myristate acetate (PMA) induced responses were limited by the amount of available peroxidase, whereas the ionomycin induced response was unaffected by the amount of extracellular peroxidase . A small increase in the response induced by the Salmonella typhimurium MR10 bacteria upon addition of peroxidase was also observed . The results indicate that stimuli inducing an intracellular response in PMNL are insensitive to the amount of extracellularly released peroxidase, whereas the response induced by stimuli also generating an extracellularly located production of oxidative metabolites are highly influenced by the amount of peroxidase available extracellularly . Furthermore, the extracellularly localized peroxidase dependency is reduced at higher luminol concentrations . The use of the luminol-amplified chemiluminescence technique in various types of scientific investigations is discussed.

Mutat Res, 1988 May, 199(1), 85 - 93
Modifying role of dietary factors on the mutagenicity of aflatoxin B1: in vitro effect of trace elements; Francis AR et al.; Using Salmonella typhimurium strains TA100 and TA98 tests have been carried out to detect the inhibitory activity of various trace elements on mutagenesis induced by aflatoxin B1 (AFB1) in the presence of a rat liver microsomal activation system . Several trace elements have shown significant modulating activity in both the strains, while a few show inhibition only in a particular strain . Among the most effective elements are copper, manganese, zinc and selenium, all of which exhibit an inhibition pattern which is dose-dependent . Copper, in particular, shows exceptional activity, since the molar excess dose of this element required to inhibit AFB1 mutagenicity by 50% has been observed to be very low . The action of trace elements is possibly mediated through interaction with microsomal enzymes, thereby modulating the formation of the reactive metabolite before modification of DNA . These results suggest that certain trace elements notably copper may have potential anticarcinogenic activity against AFB1.

J Bacteriol, 1988 May, 170(5), 2379 - 82
Transcriptional regulation of the proC gene of Salmonella typhimurium; Brady RA et al.; We found that the expression of beta-galactosidase in Salmonella typhimurium strains carrying proC-lacZ fusions was neither repressed by excess proline nor derepressed by proline limitation . Except for a three- to fourfold decrease in the beta-galactosidase specific activity under conditions causing a severely reduced growth rate, the expression of the proC-lacZ fusions was nearly invariant under a variety of culture conditions . Thus, the proC gene is unlike most other amino acid biosynthetic genes in that its expression is nearly constitutive.

Microb Pathog, 1988 May, 4(5), 385 - 91
Plasmid-associated virulence of Salmonella enteritidis; Hovi M et al.; Plasmid-associated virulence of Salmonella enteritidis was studied using plasmid-cured and plasmid-reintroduced strains . The plasmidless strain was unable to grow in the liver of mice after intravenous inoculation . Reintroduction of the plasmid pEX106 from the original S . enteritidis fully restored its capacity to grow in the mice . The plasmid pEX102 of Salmonella typhimurium introduced into the plasmid-cured S . enteritidis had a similar effect . The smooth lipopolysaccharide character of the S . enteritidis strains was not affected by the presence or absence of the plasmid, and the same was true of their high resistance to complement in guinea-pig serum as such or with added antibody.

Can J Microbiol, 1988 May, 34(5), 686 - 7
A chromosomal mutation mediating increased expression of pyrE in Salmonella typhimurium is located within the proposed attenuator; Neuhard J et al.; A chromosomal mutation resulting in 15- to 20-fold increased expression of the Salmonella typhimurium pyrE gene has been cloned and sequenced . The mutation was found to be a single base-pair transition of GC to AT, and occurred within a region of dyad symmetry (attenuator) located just upstream of the pyrE structural gene.

J Appl Bacteriol, 1988 May, 64(5), 459 - 63
Inactivation of bacteria by Purogene; Harakeh S et al.; The bacteriocidal efficacy of Purogene, a stabilized aqueous solution of chlorine dioxide (ClO2) was examined using bacteria of concern to public health . The organisms tested were: Escherichia coli, Pseudomonas aeruginosa, Yersinia enterocolitica, Klebsiella pneumoniae, Streptococcus pyogenes Group A, Salmonella typhimurium and Bacillus subtilis . The test organisms responded differently to inactivation by Purogene . At least a 4 log reduction in bacterial counts was noted when Purogene was applied at a concentration of 0.75 mg/l . Since Purogene is a stabilized complex, it was necessary to provide a chemical environment suitable for the release of ClO2 in this solution . This was done by varying the pH of Purogene from 3.5 to 8.6 (pH of Purogene is 8.6) while keeping the pH of the experimental medium constant (pH 7.0) . The results showed that Purogene was most efficacious at the lowest pH tested (pH 3.5) . This indicates that as chlorine dioxide solutions were reduced to chlorite (which predominates at pH 8.6), their bacteriocidal efficacy was reduced, suggesting free chlorine dioxide as the active disinfecting species.

Biokhimiia, 1988 May, 53(5), 842 - 7
{Lipopolysaccharide-induced hydrolysis of plasmalogenic phosphatidylethanolamine in human platelets}; Viktorov AV et al.; The composition of human platelet major phospholipids-phosphatidylcholine (PC), phosphatidylinositol (PI), phosphatidylserine (PS), phosphatidic acid (PA), sphingomyelin (SM), plasmalogenic and diacyl species of phosphatidylethanolamine (PPE and APE, respectively) was quantitatively analyzed by high performance liquid chromatography . Incubation (10 min, 37 degrees C) of washed platelets with lipopolysaccharide B (LPS) of Salmonella typhimurium was found to produce (in the absence of aggregation) marked hydrolysis of PI (ca . 15%) and PPE (ca . 19%) containing the bulk of polyenic fatty acids . PC and APE were less degraded (8-9%), while the amounts of PS and SM were practically unchanged and the level of PA rose by 20% . Addition of thrombin to LPS-pretreated platelets resulted in their more rapid aggregation which was accompanied by a decreased and nearly equal hydrolysis of APE and PPE (7-8%) as compared with control platelets (10 and 12%, respectively) . The extent to which PI was degraded (ca . 34%), by the action of thrombin was not affected by preliminary incubation with LPS . It is suggested that thrombin (as well as LPS) activating endogenous phospholipase(s) A2 can liberate from PPE not only arachidonic acid but also other essential polyenic fatty acids present in PPE in relatively high amounts . Besides, the agents studied may activate the intrinsic platelet system of rapid arachidonoyl transfer from diacyl PC and PE to PPE.

Arch Fr Pediatr, 1988 May, 45(5), 337 - 9
{Recurrent infections caused by Salmonella typhimurium}; Lachaux A et al.; We report the case of a 27 month-old girl with recurrent Salmonella typhi murium infections . The study of the neutrophil cells showed a transitory selective deficiency of the chemiluminescent response . After 5 months of pefloxacine therapy, recovery was obtained.

Chem Res Toxicol, 1988 May-Jun, 1(3), 175 - 8
Thioacylating intermediates as metabolites of S-(1,2-dichlorovinyl)-L-cysteine and S-(1,2,2-trichlorovinyl)-L-cysteine formed by cysteine conjugate beta-lyase; Dekant W et al.; The bioactivation mechanism of S-(1,2-dichlorovinyl)-L-cysteine (DCVC) and S-(1,2,2-trichlorovinyl)-L-cysteine (TCVC) was studied with cysteine conjugate beta-lyase (beta-lyase) from Salmonella typhimurium and with the pyridoxal phosphate model N-dodecylpyridoxal bromide (PL-Br) as catalysts and with GC/MS to identify the metabolites formed . PL-Br converted S-2-benzothiazolyl-L-cysteine to 2-mercaptobenzothiazole and S-benzyl-L-cysteine to benzyl mercaptan, demonstrating the ability of PL-Br to serve as a model for beta-lyase . PL-Br and bacterial beta-lyase converted DCVC to chloroacetic acid and chlorothionoacetic acid and TCVC to dichloroacetic acid . Incubations of PL-Br with the S-conjugates in the presence of diethylamine resulted in the formation of N,N-diethylchlorothioacetamide from DCVC and of N,N-diethyldichlorothioacetamide from TCVC . Attempts to trap the enethiols, which are the expected initial products formed by beta-elimination, by reaction with methyl iodide in incubations with the beta-lyase model were not successful . The formation of thioacylating agents from the enethiols may contribute to the cytotoxic and mutagenic effects of DCVC and TCVC.

Vet Microbiol, 1988 May, 17(1), 59 - 64
The effect of halofuginone on the excretion of Salmonella typhimurium by experimentally infected chickens; Barrow PA et al.; The effect of feeding halofuginone at 3 and 6 ppm on the excretion of Salmonella typhimurium by experimentally infected chickens was studied . A standardized procedure was used involving the oral inoculation of 72-h-old specific pathogen-free chickens with 10(8) organisms of a nalidixic acid-resistant mutant of a strain of S . typhimurium . At weekly intervals, cloacal swabs were taken and a semi-quantitative assessment was made of the numbers of Salmonella organisms excreted . When compared with the control group of infected chickens fed unmedicated food, the group fed halofuginone at 3 ppm showed no significant increase in excretion rate . The group fed 6 ppm showed a slight increase in excretion which was statistically significant.

Mutat Res, 1988 May, 199(1), 235 - 42
Effect of the homokaryotic state of the uvs-2 allele in Neurospora crassa on formaldehyde-induced killing and ad-3 mutation; de Serres FJ et al.; Formaldehyde was tested for its killing and mutagenic activities in the ad-3 forward-mutation test in Neurospora crassa . The test was conducted in 3 two-component heterokaryons (dikaryons) of N . crassa in order to determine the effect of the uvs-2 allele, which causes a defect in nucleotide excision repair, on formaldehyde-induced killing and the induction of ad-3 mutants . These dikaryons were homokaryotic for uvs-2+ (H-12), homokaryotic for usv-2 (H-59), and heterokaryotic for uvs-2 (H-71) . Formaldehyde induced killing and ad-3 mutants in H-12, but the presence of uvs-2 in the homokaryotic state (H-59) resulted in a 9-fold increase in killing and a 40-fold increase in the induction of ad-3 mutants . This increased sensitivity to formaldehyde-induced killing and mutation conferred by uvs-2 in the homokaryotic state (H-59 vs . H-12) is similar to that noted by others in Escherichia coli . Salmonella typhimurium and Saccharomyces cerevisiae . The dikaryon heterokaryotic for uvs-2 (H-71) has the same sensitivity to formaldehyde-induced ad-3 mutation as H-12, indicating that uvs-2 is recessive to uvs-2+.

Infect Immun, 1988 May, 56(5), 1076 - 83
Inactivation of suppressor T-cell activity by nontoxic monophosphoryl lipid A; Baker PJ et al.; Treatment with nontoxic monophosphoryl lipid A (MPL), which was derived from a polysaccharide-deficient, heptoseless Re mutant of Salmonella typhimurium, was found to inactivate suppressor T-cell activity, as evidenced by a decrease in the degree of low-dose immunological paralysis expressed and an increase in the magnitude of the antibody response to type III pneumococcal polysaccharide . The effects produced, which could not be attributed to the polyclonal activation of immune B cells by MPL, were dependent upon the dose of MPL used, as well as the time when MPL was given relative to low-dose priming or immunization with type III pneumococcal polysaccharide . Neither amplifier nor helper T-cell activity was decreased by treatment with the same, or larger, doses of MPL . The significance of these findings to the use of MPL as an immunological adjuvant or an immunomodulating agent is discussed.

Mol Gen Genet, 1988 May, 212(2), 287 - 94
Regulation of pyrC expression in Salmonella typhimurium: identification of a regulatory region; Kelln RA et al.; Deletion analysis of a plasmid carrying the entire pyrC gene of Salmonella typhimurium served to localize the regulatory region within a 120 base pair DNA fragment comprising the promoter-leader region and the first 10 codons of pyrC . A region of dyad symmetry is present in the leader DNA and may result in the formation of a stable hairpin in the transcript with part of the Shine-Dalgarno sequence included in the stem . Four independently-isolated regulatory mutants, overexpressing pyrC, were found to have point mutations within the symmetry region and, significantly, the mutations occurred in sequences pertaining to either side of the stem of the putative hairpin of the transcript . All four mutations would decrease the stability of the hairpin, suggesting that pyrC expression is controlled at the level of translation . Additional evidence for translational control was provided by the finding that synthesis of galactokinase mediated from a pyrC-galK transcriptional fusion is not regulated by pyrimidines . The importance of the symmetry region in the leader was further emphasized by showing that pyrC expression is strongly affected when this region is deleted, inverted, or structured as a tandem duplication.

Carcinogenesis, 1988 May, 9(5), 771 - 7
Glutathione mutagenesis in Salmonella typhimurium is a gamma-glutamyltranspeptidase-enhanced process involving active oxygen species; Stark AA et al.; Reduced glutathione (GSH) is mutagenic in Salmonella in the presence of gamma-glutamyltranspeptidase (GGT), with the highest response obtained in strain TA102 . Reduced cysteinylglycine, one of the products of GGT metabolism of GSH, is mutagenic in the absence of GGT . In strain TA102, GSH mutagenesis was dependent on molecular oxygen, enhanced by iron, inhibited by EDTA, desferrioxamine mesylate, mannitol, butylated hydroxyanisole, peroxidase and catalase, but not by superoxide dismutase . Binding of GSH or its GGT-dependent metabolites to DNA in vitro was not detected . This is consistent with a model of an indirect mechanism of mutagenesis, i.e . cleavage of GSH by GGT, followed by facile auto-oxidation of the resulting cysteinylglycine, with the production of free radicals which lead to the (pen)ultimate mutagen, H2O2.

Mol Gen Genet, 1988 May, 212(2), 246 - 51
Cloning and nucleotide sequence of the Salmonella typhimurium LT2 metF gene and its homology with the corresponding sequence of Escherichia coli; Stauffer GV et al.; The Salmonella typhimurium LT2 metF gene, encoding 5,10-methylenetetrahydrofolate reductase, has been cloned . Strains with multicopy plasmids carrying the metF gene overproduce the enzyme 44-fold . The nucleotide sequence of the metF gene was determined, and an open reading frame of 888 nucleotides was identified . The polypeptide deduced from the DNA sequence contains 296 amino acids and has a molecular weight of 33,135 daltons . Mung bean nuclease mapping experiments located the transcription start point and possible transcription termination region for the gene . There is a 25 bp nucleotide sequence between the translation termination site and the possible transcription termination region . This region possesses a GC-rich sequence that could form a stable stem and loop structure once transcribed (delta G = -9 kcal/mol), followed by an AT-rich sequence, both of which are characteristic of rho-independent transcription terminators . The nucleotide and deduced amino acid sequences of the S . typhimurium metF gene are compared with the corresponding sequences of the Escherichia coli metF gene . The nucleotide sequences show 85% homology . Most of the nucleotide differences found do not alter the amino acid sequences, which show 95% homology . The results also show that a change has occurred in the metF region of the S . typhimurium chromosome as compared to the E . coli chromosome.

APMIS, 1988 May, 96(5), 400 - 6
Vesicular stomatitis virus infection enhances invasiveness of Salmonella typhimurium; Bukholm G et al.; When mouse fibroblast L-929 cells were pre-infected with vesicular stomatitis virus, an enhancement of invasiveness by Salmonella typhimurium was observed . The effect was more pronounced when higher virus doses were used . Short-time (5 h) pre-incubation with virus caused a moderate enhancement of invasiveness . When virus pre-incubation time was increased to 8 h or 13 h, a further enhancement was observed . Results obtained after pre-incubation with UV inactivated virus were similar to that achieved by the short-time pre-incubation with the corresponding viable virus preparation . This indicates (i) an early phase of virus infection, when virus causes enhancement of invasiveness that is not dependent on viral nucleic acid induced metabolism, and (ii) a later phase, when virus-induced metabolism is necessary for the enhancement . When virus and bacteria were given concomitantly to infant mice, lethality was increased compared to groups that only received virus or bacteria . The data indicate that vesicular stomatitis virus aggravates infection with a facultatively intracellular bacterium, partly by enhancing the invasiveness of the bacteria.

J Bacteriol, 1988 May, 170(5), 2221 - 8
Identification and characterization of the products of six region III flagellar genes (flaAII.3 through flaQII) of Salmonella typhimurium; Homma M et al.; A portion of flagellar region III of the Salmonella typhimurium genome has been cloned and shown to contain six genes: flaAII.3, flaAIII, flaS, flaR, flaQI, and flaQII . Of these, all but flaQI were known to exist from mutant studies; the former flaQ has been renamed flaQII . The genes were shown by minicell analysis to encode proteins with apparent molecular masses of 28, 48, 15, 46, 17, and 37 kilodaltons, respectively . The presence of a flagellar-gene-specific promoter in the vicinity of flaQI was established by testing expression of the plasmid-encoded tetracycline resistance gene in artificial constructions . In minicell preparations, the flaAII.3 and flaR products were found principally in the cytoplasmic fraction; the rest were found principally in the membrane fraction . A comparison between the homologous genes of S . typhimurium and Escherichia coli confirmed that their genomic organizations were similar and that their products had similar molecular masses and isoelectric points.

J Bacteriol, 1988 May, 170(5), 2185 - 91
Analysis of lipopolysaccharide biosynthesis in Salmonella typhimurium and Escherichia coli by using agents which specifically block incorporation of 3-deoxy-D-manno-octulosonate; Goldman RC et al.; Antibacterial agents which specifically inhibit CTP:CMP-3-deoxy-D-manno-octulosonate cytidylyltransferase activity were used to block the incorporation of 3-deoxy-D-manno-octulosonate (KDO) into lipopolysaccharide . Lipopolysaccharide synthesis ceased, molecules similar in structure to lipid A accumulated, and bacterial growth ceased following addition of such agents to cultures of Salmonella typhimurium and Escherichia coli . Although four major species of lipid A accumulated in S . typhimurium, their kinetics of accumulation were different . The least polar of the major species was IVA {O-(2-amino-2-deoxy-beta-D-glucopyranosyl)-(1----6)-2-amino-2-deoxy-a lph a- D-glucose, acylated at positions 2, 3, 2', and 3' with beta-hydroxymyristoyl groups and bearing phosphates at positions 1 and 4'}, a molecule previously isolated from bacteria containing a kdsA mutation (C . R . H . Raetz, S . Purcell, M . V . Meyer, N . Qureshi, and K . Takayama, J . Biol . Chem . 260:16080-16088, 1985) . Species IVA accumulated first and to the greatest extent following addition of the inhibitor, with other more polar derivatives appearing only after IVA attained half its maximal level . In contrast, only two major species of precursor accumulated in E . coli following addition of the inhibitor . One of these species was identical to IVA from S . typhimurium on the basis of chemical composition, fast atom bombardment mass spectroscopy, and comigration on Silica Gel H, and it also accumulated prior to a more polar species of related structure . We conclude that the addition of KDO to precursor species IVA is the major pathway of lipid A-KDO formation in both S . typhimurium LT2 and E . coli and that accumulation of the more polar species lacking KDO only occurs in response to accumulation of species IVA following inhibition of the normal pathway.

J Bacteriol, 1988 May, 170(5), 2113 - 20
Structural gene for NAD synthetase in Salmonella typhimurium; Hughes KT et al.; We have identified the structural gene for NAD synthetase, which catalyzes the final metabolic step in NAD biosynthesis . This gene, designated nadE, is located between gdh and nit at 27 min on the Salmonella typhimurium chromosome . Mutants of nadE include those with a temperature-sensitive lethal phenotype; these strains accumulate large internal pools of nicotinic acid adenine dinucleotide, the substrate for NAD synthetase . Native gel electrophoresis experiments suggest that NAD synthetase is a multimeric enzyme of at least two subunits and that subunits from Escherichia coli and S . typhimurium interact to form an active heteromultimer.

Zh Mikrobiol Epidemiol Immunobiol, 1988 May, (5), 81 - 4
{Changes in the bactericidal activity of macrophages from mice with various degrees of resistance to Salmonella typhimurium infection as affected by interferon}; Spivak NIa et al.; The bactericidal activity of mouse macrophages with different sensitivity to Salmonella infection has been studied . The sensitivity of BALB/c mice to S . typhimurium infection is associated with the low bactericidal activity of their macrophages . The introduction of interferon stimulates the bactericidal activity of macrophages sensitive to Salmonella infection of mice, which sharply enhances the resistance of the animals to this infection.

Biochem Biophys Res Commun, 1988 Apr 29, 152(2), 843 - 8
A male-specific renal cytochrome P-450 isozyme(s) responsible for mutagenic activation of 3-methoxy-4-aminoazobenzene in mice; Degawa M et al.; Renal microsomes from male mice (BALB/c, DBA/2 and BALB/c x DBA/2 F1) showed about 10-fold greater activity for mediating mutagenic activation of 3-methoxy-4-aminoazobenzene (3-MeO-AAB) toward Salmonella typhimurium TA98 than did the corresponding hepatic microsomes, as compared on the basis of nmol of microsomal cytochrome P-450 . On the other hand, female renal microsomes and other extrahepatic microsomes (lung, small intestine and colon) in both sexes of mice showed little or no activity for converting 3-MeO-AAB to mutagen(s) . The mutagenic activation of 3-MeO-AAB with the male renal enzyme(s) was definitely inhibited by cytochrome P-450 inhibitors, 7,8-benzoflavone and SKF 525A . All these findings suggest that in mice, there is a male-specific renal 3-MeO-AAB activation enzyme(s), a cytochrome P-450 isozyme(s), which is different, at least in proportion and/or in nature, from hepatic cytochrome P-450 isozymes.

J Biol Chem, 1988 Apr 15, 263(11), 5061 - 9
Purification and characterization of the fructose-inducible HPr-like protein, FPr, and the fructose-specific enzyme III of the phosphoenolpyruvate: sugar phosphotransferase system of Salmonella typhimurium; Sutrina SL et al.; The proteins comprising the fructose-specific phosphoenolpyruvate:sugar phosphotransferase system were investigated using a strain of Salmonella typhimurium which lacks the general phosphotransferase system proteins, HPr and Enzyme I, synthesizes the fructose phosphotransferase system proteins, FPr, Enzyme IIfru, Enzyme IIIfru, and fructose-1-phosphate kinase, constitutively, and expresses the Enzyme I-like protein Enzyme I . Enzyme I activity was found in the cytoplasmic fraction, Enzyme IIfru in the membrane fraction, and FPr and Enzyme IIIfru activities were distributed between the two fractions . Extraction of membranes with butanol and urea led to quantitative release of the membrane-associated Enzyme IIIfru and FPr activities, while Enzyme IIfru remained with the membranes . FPr was purified to homogeneity using ion exchange chromatography, gel filtration, and reversed phase high pressure liquid chromatography (HPLC), and its amino acid composition and N-terminal sequence were determined . A complex of FPr and Enzyme IIIfru (Mr 50,000) was also purified to near homogeneity using ion exchange chromatography, gel filtration, and chromatography on hydroxylapatite . When the purified complex was analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, it was visualized as two protein bands with mobilities corresponding to molecular weights of about 40,000 (Enzyme IIIfru) and 9,000 (FPr) . Neither the FPr and Enzyme IIIfru activities nor the proteins represented by these two bands separated during the above chromatography steps or using any of several other techniques, including reversed phase HPLC, indicating a very tight association . Active Enzyme IIIfru free of FPr was never isolated or observed . The proteins could be separated in denatured form by gel filtration in the presence of guanidine HCl or urea . Free FPr and the FPr-Enzyme IIIfru complex were characterized, and the properties of free and complexed FPr were compared to those of HPr.

Science, 1988 Apr 15, 240(4850), 336 - 8
Oral Salmonella typhimurium vaccine expressing circumsporozoite protein protects against malaria; Sadoff JC et al.; Immunization with radiation-attenuated malaria sporozoites induces potent cellular immune responses, but the target antigens are unknown and have not previously been elicited by subunit vaccines prepared from the circumsporozoite (CS) protein . A method is described here for inducing protective cell-mediated immunity to sporozoites by immunization with attenuated Salmonella typhimurium transformed with the Plasmodium berghei CS gene . These transformants constitutively express CS antigens and, when used to immunize mice orally, colonize the liver, induce antigen-specific cell-mediated immunity, and protect mice against sporozoite challenge in the absence of antisporozoite antibodies . These data indicate that the CS protein contains T cell epitopes capable of inducing protective cell-mediated immunity, and emphasize the importance of proper antigen presentation in generating this response . Analogous, orally administered vaccines against human malaria might be feasible.

Biochemistry, 1988 Apr 5, 27(7), 2282 - 7
Glucosamine synthetase from Escherichia coli: kinetic mechanism and inhibition by N3-fumaroyl-L-2,3-diaminopropionic derivatives; Badet B et al.; N3-(4-Methoxyfumaroyl)-L-2,3-diaminopropionic acid (FMDP; 1, R = OMe), a member of a new class of glutamine analogues, has been investigated as an inhibitor of pure Escherichia coli glucosamine synthetase . Product and dead-end inhibition studies indicate an ordered association to the enzyme with the sugar molecule binding prior to substrate or inhibitor . The inactivation exhibits pseudo-first-order kinetics, is irreversible, and occurs faster in the presence of fructose 6-phosphate, a behavior previously reported {Chmara, H., Andruszkiewicz, R., & Borowski, E . (1986) Biochim . Biophys . Acta 870,357} for the partially purified enzyme from Salmonella typhimurium . The ratio kinact/Kirr of 5500 makes compound 1 (R = OMe) one of the most efficient inhibitors of glucosamine synthetase to date . Inhibition occurs with partial covalent incorporation of L-FMDP into glucosamine synthetase . In the presence of fructose 6-phosphate, enzyme inactivation with {2-3H}-DL-FMDP is associated with the incorporation of 0.75 equiv of inhibitor and with the modification of 0.78 thiol residue per enzyme subunit . This result is the first evidence for covalent entrapment of the entire inhibitor molecule following FMDP-mediated glucosamine synthetase inactivation . Preliminary inactivation with 6-diazo-5-oxo-L-norleucine, known to alkylate selectively the NH2-terminal cysteine residue, completely prevents radioactivity incorporation . Therefore, this inhibitor is postulated to covalently modify glucosamine synthetase through direct addition of the thiol nucleophile from the terminal cysteine residue to the Michael acceptor 1, so acting as an affinity label rather than a mechanism-based inhibitor.

Mol Gen Mikrobiol Virusol, 1988 Apr, (4), 44 - 8
{Sensitivity of Vibrio cholerae to the lethal and mutagenic effects of UV-irradiation mediated by the presence of plasmids}; Tiganova IG et al.; The effect of UV-irradiation on Vibrio cholerae cells and its changes mediated by the plasmid R245 have been studied . Vibrio cholerae strains 569B and RV31 have been shown to be considerably more sensitive to lethal effect of UV-irradiation as compared with Escherichia coli and Salmonella typhimurium cells . Highly toxigenic strain 569B and practically atoxigenic strain RV31 have the same UV-sensitivity . Lethal effect of UV-irradiation on Vibrio cholerae cells is increased when the irradiated cells are plated on enriched media . UV-induction of mutations was not registered in plasmidless strains of Vibrio cholerae . Plasmid R245 increases UV-resistance of vibrio cells and makes them UV-mutable.

Carcinogenesis, 1988 Apr, 9(4), 567 - 71
Hepatic cytochrome P-450 isozyme(s) induced by dietary carcinogenic aromatic amines preferentially in female mice of DBA/2 and other strains; Degawa M et al.; DBA/2, BALB/c or (BALB/c X DBA/2)F1 (CDF1) mice of both sexes were treated for 1 week with a dietary hepatocarcinogenic tryptophan pyrolysate component (Trp P-1 or Trp P-2), and the activity of hepatic microsomal enzyme(s) for mutagenic activations of Trp P-1 and Trp P-2 were assessed by means of a mutation test with Salmonella typhimurium TA98 . In both Ah-responsive (BALB/c and CDF1) and Ah-nonresponsive (DBA/2) mice, the dietary treatment with Trp P-1 or Trp P-2 resulted in a significant increase of the enzyme activity for mutagenic activations of Trp P-1 and Trp P-2 in females but not in males, except the case of male BALB/c mice treated with dietary Trp P-1 . Also induction of enzyme(s) in female mice was suppressed by an administration of testosterone . The induced hepatic microsomal enzyme(s) was demonstrated to be cytochrome P-450 isozyme(s) (mol . wt of 55,000 daltons) by immunoblots with use of an anti-rat cytochrome P-448 monoclonal antibody and by selective inhibition of the activity by addition of 7,8-benzoflavone into the mutation assay system . These findings indicate that carcinogenic aromatic amines such as Trp P-1 and Trp P-2 are able to induce hepatic cytochrome P-450 isozyme(s) not only in Ah-responsive mice (BALB/c and CDF1) but also in Ah-nonresponsive DBA/2 mice and that the cytochrome P-450 induction is controlled by androgen(s).

Mutat Res, 1988 Apr, 204(4), 683 - 8
Genotoxicity of epoxy resin hardeners in the hepatocyte primary culture/DNA repair test; Mori H et al.; The genotoxicity of 9 chemicals used as epoxy resin hardeners was examined in the DNA repair test with rat hepatocytes . DNA repair synthesis was elicited by 7 chemicals, i.e., 4-aminodiphenyl ether, 4,4-diaminodiphenyl ether, 3,4,4'-triaminodiphenyl ether, 3,3'-dichloro-4,4'-diaminodiphenyl ether, 1,3-phenylenedi-4-aminophenyl ether, 4,4'-diaminodiphenyl methane and 4,4'-methylene-bis(2-chloroaniline) . The positive results obtained with 4 epoxy resin hardeners of unknown carcinogenicity, i.e., 4-amino-diphenyl ether, 3,4,4'-triaminodiphenyl ether, 3,3'-dichloro-4,4'-diaminodiphenyl ether and 1,3-phenylene-di-4-aminophenyl ether suggest that they may be carcinogens . The genotoxicity of 1,4-phenylene-di-4-aminophenyl ether, of unknown carcinogenicity, and 4,4'-diaminodiphenyl sulfone, for which there is no sound proof of carcinogenicity, was not confirmed in the DNA repair test . The result with 4,4'-diaminodiphenyl sulfone was in agreement with its lack of mutagenicity in Salmonella typhimurium.

Mutat Res, 1988 Apr, 203(2), 95 - 101
Effect of dipyridoimidazole pretreatment on mutagen activation in rats; de Meester C et al.; Rats were pretreated with a single oral dose of different mutagenic fractions obtained from glutamic acid pyrolysate: Glu-P-2 (2-amino-dipyrido{1,2-a:3',2'-d}imidazole), Glu-P-3 (3-amino-4,6-dimethyldipyrido{1,2-a:3',2'-d}imidazole), the tar residue and a basic extract (B2) . The liver S9 fractions of these animals were used to investigate the mutagenic activation of 3 promutagens (2-aminoanthracene, Glu-P-2 and Glu-P-3) in Salmonella typhimurium strain TA1538 . Different factors were analyzed; influence of the structure of the compounds administered, doses, time interval between pretreatment and sacrifice and sex of the rats . Interpretation of the hepatic induction effects was complicated, however, by the fact that simple oral pretreatment with the solvents (DMSO or ethanol) enhances the activation of the substrates tested for mutagenicity . A dose-effect relationship was found between 2-AA mutagenic activation and Glu-P-2 pretreatment . Glu-P-3 induced the activation of 2-AA more than did Glu-P-2, in the male as in the female . The mutagenicity of 2-AA activated with S9 from male rats was found to be optimal after 24 h pretreatment with 20 mg Glu-P-2/kg b.w . The mutagenicity of Glu-P-2 was poorly influenced by the different pretreatments applied to either the males or the females, whereas some dose effect was found in the autoinduction of Glu-P-2 mutagenicity . Compared to Glu-P-2, the mutagenicity of Glu-P-3 was increased at higher levels when tested with S9 from males pretreated with the same compound, but no differences were observed between males and females.

Infect Immun, 1988 Apr, 56(4), 1000 - 2
Effect of protein malnutrition on salmonellosis and fever; Bradley SF et al.; Protein-malnourished rats had greater numbers of bacteria in their livers and spleens compared with numbers in control rats following a sublethal intraperitoneal dose of Salmonella typhimurium . However, the febrile responses of both groups of rats to infection were similar . The ability to mount a normal febrile response does not necessarily reflect the ability of the host to contain an infection.

Vet Immunol Immunopathol, 1988 Apr, 18(3), 259 - 67
Immune response of sheep to oral and subcutaneous administration of live aromatic-dependent mutant of Salmonella typhimurium (SL1479); Lascelles AK et al.; The major objective of the present study was to determine whether oral immunization with a live aromatic-dependent strain of Salmonella typhimurium (SL1479) was capable of stimulating an intestinal immune response in sheep similar to that induced by combined intraperitoneal injection followed by oral boosting . The results showed that repeated oral immunization was incapable of stimulating an anti-flagella antibody containing cell (ACC) response in the lamina propria of the intestine even though primary oral administration of 5 x 10(9) live SL1479 gave rise to an ACC response in intestinal lymph which was predominantly of the IgM isotype . ACC reached a peak 9-10 days after oral administration when ACC comprised 0.5-1% of total lymphocytes in lymph . An ACC response of similar isotope specificity also occurred in popliteal prefemoral lymph of unprimed sheep following regional subcutaneous injection of SL1479 . Oral administration of SL1479 to orally primed sheep did not reinvoke an ACC response in lymph although IgG1-ACC were observed in medullary cords of mesenteric lymph nodes of sheep 6-8 days after the booster dose of SL1479 . The results suggest that the protective immunity elicited by oral administration of SL1479 cannot be attributed to induction of a local intestinal antibody production.

J Dairy Sci, 1988 Apr, 71(4), 1078 - 84
Changes in blastogenic activity of bovine blood mononuclear cells throughout the nonlactating period; Torre PM et al.; Mononuclear cells were isolated from bovine blood by density gradient centrifugation to determine variation in mitogen-induced mononuclear cell activity throughout the nonlactating period . In a preliminary study, optimum concentrations of Concanavalin A, phytohemagglutinin, Salmonella typhimurium lipopolysaccharide, and three Escherichia coli lipopolysaccharides were determined using six cows as blood donors . Concanavalin A, phytohemagglutinin, and E . coli 0111:B4 lipopolysaccharide were selected for further studies . Mitogenic responses of blood mononuclear cells from five cows were evaluated at drying off, 14 to 16 and 28 to 30 d of involution, 12 to 14 d prepartum, and at parturition . Concanavalin A-treated cells exhibited greater blastogenic activity than phytohemagglutinin-treated cells . Response of cells to Concanavalin A increased slightly through 28 to 30 d of involution and decreased markedly at parturition . Blastogenic activity of cells treated with phytohemagglutinin decreased throughout the nonlactating period and was lowest at parturition . Activity of lipopolysaccharide-treated mononuclear cells increased through 28 to 30 d of involution . However, response of mononuclear cells to lipopolysaccharide was minimal compared with response to Concanavalin A and phytohemagglutinin . Variation in peripheral blood mononuclear cell activity throughout involution may parallel mammary gland mononuclear cell activity, affecting susceptibility of the mammary gland to new intramammary infections.

Vaccine, 1988 Apr, 6(2), 155 - 60
Avirulent Salmonella typhimurium delta cya delta crp oral vaccine strains expressing a streptococcal colonization and virulence antigen; Curtiss R 3rd et al.; Salmonella typhimurium SR-11 strains lacking adenylate cyclase and the cyclic AMP receptor protein (CRP) due to deletion (delta) mutations in the cya and crp genes, respectively, are avirulent for mice and induce high level protective immunity against subsequent challenge with wild-type virulent S . typhimurium SR-11 cells . The avirulence of these delta cya delta crp mutants has been enhanced by elimination of the 100 kb virulence plasmid pStSR100 without impairing immunogenicity . The present report confirms the avirulence and immunogenicity of these mutant strains, demonstrates that immunization of both four- and eight-week-old mice has no adverse effect on weight gain, and that immunity lasts at least ninety days following initial immunization . Avirulent S . typhimurium strains have been endowed with the ability to produce several streptococcal colonization and virulence antigens for the purpose of constructing recombinant bivalent oral vaccine strains . Important antigenic determinants of the Streptococcus sobrinus surface protein antigen A (SpaA), presumed to be a critical colonization antigen of S . sobrinus, are expressed at high level by the delta cya delta crp S . typhimurium strains . The recombinant vaccine strains are stable in vitro and in animals (for a period of at least eight days) where they localize to the gut-associated lymphoid tissue (GALT).

Fundam Appl Toxicol, 1988 Apr, 10(3), 537 - 46
An evaluation of the genotoxic potential of glyphosate; Li AP et al.; The potential genotoxicity of glyphosate, the active ingredient in Roundup herbicide, was tested in a variety of well-established in vitro and in vivo assays including the Salmonella typhimurium and Escherichia coli WP-2 reversion assays, recombination (rec-assay) with Bacillus subtilis . Chinese hamster ovary cell gene mutation assay at the hypoxanthine/guanine phosphoribosyl transferase gene locus, hepatocyte primary culture/DNA repair assay, and in vivo cytogenetics assay in rat bone marrow . No genotoxic activity was observed in the assays performed . The data suggest that glyphosate should not pose a genetic risk to man.

Can J Vet Res, 1988 Apr, 52(2), 264 - 8
The effect of sodium chloride extract and commercial lipopolysaccharides of Escherichia coli and Salmonella typhimurium on chickens; Nakamura K et al.; In chickens inoculated into the heart with a sodium chloride extract of Escherichia coli strain (serotype O2) isolated from a chicken with colibacillosis, characteristic hemorrhages into the anterior chamber of the eyes (hyphema) were found . Significant lesions were limited to the eyes . Cyclophosphamide-treated chickens were more sensitive to the extract than untreated chickens and hyphema was usually seen in association with hemorrhages of the iris . These activities were not reduced by heating the extract at 60 degrees C for one hour or by trypsin digestion . Chickens inoculated into the heart with commercial lipopolysaccharides of E . coli (serotypes O111:B4 and O55:B5) and Salmonella typhimurium showed similar lesions in the eyes as the chickens inoculated with the sodium chloride extract . These findings suggest that the endotoxin may induce hyphema in chickens.

APMIS, 1988 Apr, 96(4), 299 - 305
Characteristics of the granulocyte chemiluminescence reaction following an interaction between human neutrophils and Salmonella typhimurium bacteria; Lock R et al.; The production of reactive oxygen metabolites by neutrophils is thought to play a key role in the host defence against invading microorganisms . The production of these oxidative metabolites can be measured as chemiluminescence . In this study, two strains of Salmonella typhimurium were used as stimuli, and the opsonin-independent CL response from neutrophils challenged with these bacteria was investigated . The strains used, S . typhimurium 395 MS and a rough (Rd Epi-2) mutant 395 MR10, differ with respect to physicochemical surface characteristics . When neutrophils were exposed to the phagocytic prey, only the MR10 bacteria induced a CL response . The response induced by the MS bacteria was less than 2% of that induced by MR10 . In order to study the relation between intra and extracellularly generated CL, systems were used which selectively inhibit the intra and extracellular CL, respectively . Using these systems it was found that a predominant part of the response was of intracellular origin . When the neutrophils were treated with cytochalasin B (5 micrograms) before the addition of the bacteria, the CL response was reduced to around 37% of the value obtained from untreated cells, and the relation between the extra and the intracellular parts of the response was changed . The mechanism(s) and biological consequences of the extracellular and intracellular generation of oxygen metabolites, respectively, are discussed.

Mutat Res, 1988 Apr, 204(4), 627 - 43
Assessment of the mutagenic potential of a fungicide Bavistin using multiple assays; Pandita TK; The fungicide Bavistin was assessed for mutagenic potential by various assays . Bavistin was found to be unable to induce gene mutation in Salmonella typhimurium, but it was able to induce transfection inhibition in Mycobacterium smegmatis . Bavistin was able to induce immediate genotoxic effects in plants but these were not carried through in development as in the long term no genotoxic effects were observed by the progeny test . Bavistin did induce micronuclei formation and did cause an increase in the ratio of normochromatic to polychromatic erythrocytes in mice . It was able to induce a very low frequency of sister-chromatid exchange in human lymphocytes and in addition, it was observed that the chemical affected the mitotic index but did not affect the cell cycle duration . Present studies indicate that the pesticide shows a positive response in 4 out of 5 different test systems (Table 8) and most of the observations support that Bavistin is genotoxic.

Mutat Res, 1988 Apr, 204(4), 615 - 21
On the mutagenic and recombinogenic activity of certain herbicides in Salmonella typhimurium and in Aspergillus nidulans; Kappas A; The plant growth-regulating hormones indole-3-acetic acid (IAA) and indole-3-butyric acid (IBA), both strong recombinogens in Aspergillus nidulans, were tested in Salmonella typhimurium strains for his revertants at a range of concentrations from 1 to 2000 micrograms/plate with and without metabolic activation and were found negative . Also 3 herbicides of the chlorophenoxy group, 2,4-(dichlorophenoxy)acetic acid (2,4-D), 2,4-(dichlorophenoxy)butyric acid (2,4-DB) and 4-chloro-2-methylphenoxyacetic acid (MCPA), which show a plant growth hormone-like activity, and 2 of the triazine group, 2-ethylamino-4-chloro-6-isopropylamino-1,3,5-triazine (atrazine) and 2,4-bis(isopropylamino)6-chloro-1,3,5-triazine (propazine) were tested in S . typhimurium for point mutations and in A . nidulans for mitotic recombination . 2,4-D and MCPA were found to be weakly mutagenic at concentrations between 250 and 750 micrograms/plate in strain TA97a and only after metabolic activation and were recombinogens by inducing mainly mitotic crossing-over in A . nidulans at concentrations of 4-48 microM and 1500-3000 microM, respectively . 2,4-DB, atrazine and propazine were negative in both the Ames and the Aspergillus tests.

Mutat Res, 1988 Apr, 204(4), 577 - 83
Activation of anti-Trypanosoma cruzi drugs to genotoxic metabolites promoted by mammalian microsomal enzymes; Ferreira RC et al.; Salmonella typhimurium TA100 and its nitroreductase-deficient derivative, TA100 NR, were used to reevaluate the mutagenic activities of benznidazole and nifurtimox . Mutagenicity and toxicity of nifurtimox were abolished in the TA100 NR tester strain under aerobic or anaerobic conditions and addition of rat liver extracts did not alter the results . However, benznidazole showed a significant mutagenicity and toxicity to the nitroreductase-deficient strain TA100 NR under hypoxic conditions . Addition of rat liver extracts enhanced the observed mutagenicity and toxicity of benznidazole even more . In the presence of O2 the genotoxic activities of benznidazole to the TA100 NR tester strain were eliminated . These results lead us to conclude that bacterial enzymes were responsible for the previously observed genotoxic effects of nifurtimox and benznidazole on S . typhimurium TA100 . Moreover, under anaerobic conditions, only benznidazole could be metabolized by mammalian nitroreductases into a mutagenic derivative.

Cancer Res, 1988 Apr 1, 48(7), 1781 - 7
Reactivity with DNA bases and mutagenicity toward Salmonella typhimurium of methylchrysene diol epoxide enantiomers; Melikian AA et al.; The reactions with DNA and mutagenic activities toward Salmonella typhimurium TA 100 of the R,S,S,R and S,R,R,S enantiomers of anti-1,2,-dihydroxy-3,4-epoxy-1,2,3,4-tetrahydro-5-methylchrysene (anti-5-MeC-1,2-diol-3,4-epoxide), anti-5-MeC-7,8-diol-9,10-epoxide, and anti-6-MeC-1,2-diol-3,4-epoxide were compared because among these compounds only the R,S,S,R enantiomer of anti-5-MeC-1,2-diol-3,4-epoxide is highly tumorigenic . The major products formed in the reaction of each racemic diol epoxide with DNA were two pairs of deoxyguanosine (dGuo) and deoxyadenosine (dAdo) adducts; one product in each pair was formed from the R,S,S,R enantiomer and the other from the S,R,R,S enantiomer of each racemic diol epoxide . Formation of products from R,S,S,R enantiomers exceeded formation of those from S,R,R,S enantiomers in each case . Among the R,S,S,R enantiomers, 5-MeC-1,2-diol-3,4-epoxide, which has a methyl group in the same bay region as the epoxide ring, was most reactive toward DNA, and in particular toward dGuo . The dGuo/dAdo adduct ratios were greater for the products formed from the R,S,S,R enantiomer compared to the S,R,R,S enantiomer of each diol epoxide . The dGuo/dAdo adduct ratios were also greater for the enantiomers of anti-5-MeC-1,2-diol-3,4-epoxide than for the enantiomers of either anti-5-MeC-7,8-diol-9,10-epoxide or anti-6-MeC-1,2-diol-3,4-epoxide . In S . typhimurium TA 100, the R,S,S,R enantiomer of anti-5-MeC-1,2-diol-3,4-epoxide was the most mutagenic compound (6700 revertants/nmol), followed by the R,S,S,R enantiomer of anti-5-MeC-7,8-diol-9,10-epoxide (1500 revertants/nmol) . The other diol epoxide enantiomers were weakly active or inactive at the doses tested . The results of this study demonstrate that both the absolute configuration of a diol epoxide and the position of the methyl group have major effects on its reactivity with DNA . The greatest reactivity is seen in an R,S,S,R enantiomer with the methyl group and epoxide ring in the same bay region, e.g., the highly tumorigenic and mutagenic 5-MeC-1R,2S-diol-3S,4R-epoxide . Comparison of the dGuo/dAdo adduct ratios of the various diol epoxides with their tumorigenic and mutagenic activities suggests that dGuo adducts are important in the expression of biological activity of methylchrysene diol epoxides.

J Immunol, 1988 Apr 1, 140(7), 2395 - 400
Pleiotropic effects of the Bcg gene . I . Antigen presentation in genetically susceptible and resistant congenic mouse strains; Denis M et al.; The Ag-presentation ability of Bcgr and Bcgs spleen cells was studied in two sets of Bcg-congenic systems; namely, the BALB/c-BALB/c.Bcgr pair and the B10.A-B10.A-Bcgr pair, by using three sonicated soluble bacterial Ag (mycobacterium bovis bacillus Calmette-Guerin, Salmonella typhimurium, and Brucella abortus) as well as a particulate Ag (heat-killed Escherichia coli) . Pulsed Bcgr spleen cells were shown to induce a stronger proliferation of the T cell-indicator system than their Bcgs counterparts . No difference in Ag-presenting ability could be shown between Bcgr and Bcgs peritoneal macrophages from normal animals . However, elicited peritoneal macrophages from immune Bcgr mice were superior in their Ag-presentation ability . Differences at the level of Ag presentation of Bcgr and Bcgs splenic cells were investigated further . Depletion of T cells and B cells did not alter the differences in Ag-presenting ability between Bcgr and Bcgs spleen cells . Furthermore, splenic dendritic cells of Bcgr or Bcgs allelic types were equally efficient in presenting bacillus Calmette-Guerin Ag to accessory cell-depleted T cells . In a final experiment, it was shown that spleen macrophages were the cell type involved in the superior Ag presentation by Bcgr splenic cells.

Mikrobiyol Bul, 1988 Apr, 22(2), 95 - 100
{Outbreak of food poisoning caused by Salmonella typhimurium}; Ulutan F et al.; In this paper, a food poisoning outbreak of 42 people who ate the sucuk (Turkish sausage flavored with garlic) which was made of the same meat has been described . Salmonella typhimurium was isolated from the stool of 20 patients and from the sucuk . Efficacy rate of Ofloxacin was 75 percent in these 20 patients treated Ofloxacin.

Avian Dis, 1988 Apr-Jun, 32(2), 324 - 9
Effect of anticoccidial and antimicrobial feed additives on prevention of Salmonella colonization of chicks treated with anaerobic cultures of chicken feces; Bailey JS et al.; Chicks were treated orally on the day of hatch with either fresh or frozen competitive exclusion (CE) cultures (native gut microflora) . Chicks were fed either unmedicated feed or one of five commercial broiler starter rations or nine experimental feed mixtures containing varying amounts and combinations of anticoccidial and antimicrobial medicaments . After 2 days, they were challenged with approximately 10(6) colony-forming units of a nalidixic-acid-resistant strain of Salmonella typhimurium . Six days later, chicks were sacrificed and ceca were analyzed for S . typhimurium . Colonization of 2-day-old chicks was prevented or at least greatly reduced in most instances by treatment of chicks with a CE culture, but the efficacy of CE broth cultures stored at -70 C diminished over time . Not all CE cultures tested gave equal protection against Salmonella colonization, and CE cultures were more susceptible to some feed additives than others . Of the commercial or experimental feed tested, only the feed containing the combination of nicarbazin and bacitracin interfered with the protective effect of the CE culture.

Avian Dis, 1988 Apr-Jun, 32(2), 215 - 9
The influence of physical and environmental variables on the in vitro attachment of Salmonella typhimurium to the ceca of chickens; McHan F et al.; This investigation was designed to study the effect of exposure time, pH, age of bird, and native intestinal microflora on the in vitro attachment of Salmonella typhimurium to the ceca of chickens . Ceca were surgically removed from chickens immediately after euthanasia, and the interiors were exposed to S . typhimurium as intact ceca with contents, intact ceca rinsed free of contents, or inverted rinsed ceca . Attachment of S . typhimurium was slightly higher in washed than in unwashed ceca . Neither pH nor age of chicks affected attachment of the organism to ceca . There was no difference in attachment of salmonellae to inverted washed ceca after 1, 2, 3, 5, and 10 min exposure, but a one log difference was noted between 10 min and 30 sec.

J Hosp Infect, 1988 Apr, 11(3), 220 - 5
Effect of chlorhexidine-containing detergent, non-medicated soap or isopropanol and the influence of neutralizer on bacterial pathogenicity; Rotter ML et al.; In handwashing experiments with Salmonella typhimurium the effect of chlorhexidine (CHX) on the pathogenicity of surviving bacteria was assessed with and without a neutralizer in a mouse model of infection . Without neutralizer the LD50 of CHX handwash fluids was raised . Neutralizer in suspensions of untreated bacteria caused a reduction of LD50 up to 1.2 logs . Thus, in contrast to soap or alcohol, CHX without neutralizer exerted a slight 'depathogenizing' action and neutralizer a slight 'pathogenizing' effect in the experimental model used . However, in comparison to the efficiency of handwashing procedures which reduce the number of bacteria available for transfer by at least 3.0 to 4.2 logs, the size of these effects seems to be negligibly small and unpredictable . Therefore, the single most important parameter in assessing the potency of disinfectants remains the reduction of viable counts with time.

Mol Gen Genet, 1988 Apr, 212(1), 134 - 41
Structure of the Saccharomyces cerevisiae URA4 gene encoding dihydroorotase; Guyonvarch A et al.; The URA4 gene of Saccharomyces cerevisiae, coding for the third enzyme of the pyrimidine pathway, has been cloned through phenotypic complementation of a ura4 mutant of S . cerevisiae . Subcloning of an original 9 kb DNA fragment, carrying the yeast URA4 gene, allowed us to localize the gene on a 2 kb ClaI--BamHI fragment . The sequence of the URA4 structural gene and surrounding DNA was determined by the dideoxynucleotide chain termination method . The URA4 gene encodes a dihydroorotase subunit of calculated molecular weight 40,600 . S1 nuclease mapping indicated that transcription of URA4 is initiated at four major start sites located at positions -41, -30, -22 and -18 . A set of potentially significant sequences was identified in the 5' OH non-coding region of the gene . The deduced amino acid sequence of dihydroorotase was examined and compared with homologous amino acid sequences of Salmonella typhimurium, Escherichia coli and Drosophila melanogaster . S . cerevisiae dihydroorotase shows 40% homology with the S . typhimurium and E . coli enzymes and 23% homology with the D . melanogaster enzyme . A potential active site has been predicted for dihydroorotase from these comparisons.

Mutat Res, 1988 Apr, 204(4), 675 - 82
DNA strand breaks and mutations caused by penbutolol, a beta blocker; Hussain SS et al.; Sixteen beta-adrenergic receptor blockers were screened for their mutagenic potential using Salmonella typhimurium strains TA98 and TA100 . All except penbutolol were found to be nonmutagenic . Penbutolol was cytotoxic to human fibroblasts and Chinese hamster V79 cells . These effects could be due to its ability to induce DNA-strand breaks detected by hydroxyapatite chromatography, which remained unrepaired within 1 h of incubation . Under the same conditions strand-breaking activity of propranolol, timolol and indenolol could not be detected . Three potential impurities of penbutolol were ineffective in causing DNA-strand breakage and one metabolite of this drug was found to be nonmutagenic.

Carcinogenesis, 1988 Apr, 9(4), 611 - 7
Influence of DT diaphorase on the mutagenicity of organic and inorganic compounds; De Flora S et al.; The metabolic activation or detoxification of mutagens and carcinogens of several chemical classes was investigated in the presence of various rat liver and lung subcellular fractions and of dicoumarol, a specific inhibitor of DT diaphorase activity . His- Salmonella typhimurium strains were used as targets of mutagenicity . Dicoumarol partially prevented the metabolic activation of some promutagens, such as the heterocyclic amines 2-amino-3,4-dimethylimidazo{4,5-f}quinoline and 3-amino-1-methyl-5H-pyrido{4,3-b}indole, and a cigarette smoke condensate . Moreover, detailed experiments, also using purified enzyme, confirmed the participation of DT diaphorase in the metabolic reduction of 4-nitroquinoline N-oxide 4NQO and of hexavalent chromium {Cr(VI)} compounds . The results obtained provide evidence for broad involvement of DT diaphorase in the metabolism of both organic and inorganic mutagens and carcinogens . Moreover, they suggest a dual role of this enzyme, providing not only a cellular detoxifying system but also, with a few substrates, an activating mechanism.

Gene, 1988 Mar 31, 63(2), 245 - 52
Analysis of the functional domains of biosynthetic threonine deaminase by comparison of the amino acid sequences of three wild-type alleles to the amino acid sequence of biodegradative threonine deaminase; Taillon BE et al.; The nucleotide sequence of the gene, ilvA, for biosynthetic threonine deaminase (Tda) from Salmonella typhimurium was determined . The deduced amino acid sequence was compared with the deduced amino acid sequences of the biosynthetic Tda from Escherichia coli K-12 (ilvA) and Saccharomyces cerevisiae (ILV1) and the biodegradative Tda from E . coli K-12 (tdc) . The comparison indicated the presence of two types of blocks of homologous amino acids . The first type of homology is in the N-terminal portion of all four isozymes of Tda and probably indicates amino acids involved in catalysis . The second type of homology is found in the C-terminal portion of the three biosynthetic isozymes and presumably is involved in either (i) the binding or interaction of the allosteric effector isoleucine with the enzyme, or (ii) subunit interactions . The sites of amino acid changes of two E . coli K-12 ilvA alleles with altered response to isoleucine are consistent with the conclusion that the C-terminal portion of biosynthetic Tda is involved in allosteric regulation.

Biochem Pharmacol, 1988 Mar 15, 37(6), 1021 - 5
Identification of the hepatic cytochrome P-450 isozymes induced and decreased by picloram; Reidy GF et al.; Microsomes from male rats treated with picloram (100 mg/kg/day) for 7 days showed a 48% decrease in 16 alpha-hydroxylase activity when incubated with (4-14C) androstenedione . These data are consistent with the assertion that picloram decreases the titer of hepatic male specific cytochrome P-450h . Several lines of evidence suggested that picloram is an inducer of hepatic cytochrome P-450 in male rats . First, SDS polyacrylamide gel electrophoresis revealed an intensified hepatic microsomal polypeptide (MW 54,000) following picloram pretreatment . This polypeptide co-migrated with protein bands which were correspondingly intensified after pretreatment with known inducers of cytochrome P-450d (3-methylcholanthrene and isosafrole) . Second, no increase in the binding of metyrapone to picloram treated microsomes was noted compared with controls, suggesting no increase in phenobarbital-inducible forms of cytochrome P-450 . Third, hepatic microsomes from picloram treated rats activated 2-amino-3-methylimidazo {4,5-f} quinoline (a cytochrome P-450d mediated catalysis) causing a 5-fold increase in the number of induced Salmonella typhimurium TA98 revertant colonies formed compared with control microsomes . Fourth, the binding of n-octylamine to hepatic microsomes from picloram-treated rats showed, like microsomes from 3-methylcholanthrene-treated rats, an increase in the proportion of high-spin cytochrome P-450 present . Cytochrome P-450d is known to be a high spin haemoprotein.

Biochem Biophys Res Commun, 1988 Mar 15, 151(2), 891 - 6
Sensory transduction in bacterial chemotaxis involves phosphotransfer between Che proteins; Wylie D et al.; The CheA protein of the Salmonella typhimurium chemotaxis system is phosphorylated by ATP . Phospho-CheA transfers its phosphoryl group to a second chemotaxis protein, CheY . Unlike phospho-CheA, phospho-CheY is relatively unstable, rapidly decaying to phosphate and CheY . We propose that phosphorylation of CheY may play a role in its function as a tumble regulator to control motor behavior in response to attractant and repellent stimuli.

Biochem Biophys Res Commun, 1988 Mar 15, 151(2), 672 - 8
Site-directed mutagenesis of the alpha subunit of tryptophan synthase from Salmonella typhimurium; Ahmed SA et al.; Site-specific mutagenesis has been used to prepare two mutant forms of the alpha subunit of tryptophan synthase from Salmonella typhimurium in which either cysteine-81 or cysteine-118 is replaced by a serine residue . These mutant proteins are potentially useful for x-ray crystallographic studies since a heavy metal binding site is specifically eliminated in each mutant . The purified mutant proteins are fully active in four reactions catalyzed by the wild type alpha 2 beta 2 complex of tryptophan synthase . However, the mutant alpha 2 beta 2 complexes dissociate more readily and are less heat-stable than the wild type alpha 2 beta 2 complex . Thus, cysteine-81 and cysteine-118 of the alpha subunit serve structural but not functional roles.

J Mol Biol, 1988 Mar 5, 200(1), 163 - 80
The 2 A resolution structure of the sulfate-binding protein involved in active transport in Salmonella typhimurium; Pflugrath JW et al.; The crystal structure of the liganded form of the sulfate-binding protein, an initial receptor for active transport of sulfate in Salmonella typhimurium, has been solved and refined at 2.0 A resolution (1 A = 0.1 nm) . The final model, which consists of 2422 non-hydrogen atoms, one sulfate substrate and 143 water molecules, yields a crystallographic R-factor of 14.0% for 16,959 reflections between 8 and 2 A . The structure deviates from ideal bond lengths and angle distances by 0.015 A and 0.037 A, respectively . The protein is ellipsoid with overall dimensions of 35 A x 35 A x 65 A and consists of two similar globular domains . The two domains are linked by three distinct peptide segments, which though widely separated in the amino acid sequence, are in close proximity in the tertiary structure . As these connecting segments are located near the periphery of the molecule, they further serve as the base or a "boundary" of the deep cleft formed between the two domains . Despite the unusual interdomain connectivity, both domains have similar supersecondary structure consisting of a central five-stranded beta-pleated sheet sandwiched by alpha-helices on either side . The arrangement of the two domains gives rise to the ellipsoidal shape and to the cleft between the two domains wherein the sulfate substrate is found and completely engulfed . A discovery of considerable importance is that the sulfate substrate is tightly held in place primarily by seven hydrogen bonds, five of which are donated by main-chain peptide NH groups, another by a serine hydroxyl and the last by the indole NH moiety of a tryptophan side-chain; there are no positively charged residues, nor cations, nor water molecules within van der Waals' distance to the sulfate dianion . All the main-chain peptide units associated with the sulfate are in turn linked (via the peptide CO group) to arrays of hydrogen bonds . Three of these arrays are composed of alternating peptide units and hydrogen bonds within the solvent-exposed part of three alpha-helices and two are linked to a histidine and an arginine residue . The sulfate-binding protein bears strong similarity to the structures of four other periplasmic binding proteins solved in our laboratory which are specific for L-arabinose, D-galactose/D-glucose, leucine/isoleucine/valine and leucine . The similarity includes the ellipsoidal shape and the two globular domain structures, each domain consisting of a central beta-pleated sheet flanked by alpha-helices.(ABSTRACT TRUNCATED AT 400 WORDS)

Immunopharmacology, 1988 Mar-Apr, 15(2), 123 - 30
Polyarthritis and the air pouch reaction: dissimilarity of adjuvant and collagen models; De Brito FB et al.; The formation of an air pouch in the subcutaneous tissues of a rat previously inoculated intradermally with Freund's mycobacterial adjuvant for the induction of arthritis, provokes a marked but transient inflammatory reaction in the cavity lining of the pouch . The dependence of this reaction on arthritis development was investigated . It was found that rats inoculated with mycobacterial adjuvant by subcutaneous or intraperitoneal injection failed to produce either a pouch reaction or develop arthritis . Intradermal injections of carrageenan, mycobacteria (M . tuberculosis in saline), Freund's incomplete adjuvant alone or containing Salmonella typhimurium lipopolysaccharide and Bordetella pertussis organisms or mycobacterial adjuvant containing egg albumin were also ineffective . Intradermal injections of type II collagen in Freund's incomplete adjuvant did induce arthritis but no pouch reaction; however, this could be elicited after direct challenge with antigen . Pretreatment of rats intraperitoneally with saline suspensions of mycobacteria or a moderate dose of cyclophosphamide prevented both the pouch reaction and arthritis developing to intradermal mycobacterial adjuvant . Pretreatment of rats with mycobacteria was without effect on type II collagen-induced arthritis . From the results of this study it would appear that the air pouch reaction and arthritis induced by adjuvant are directly associated . The inability of collagen to induce a similar reaction demonstrates a fundamental dissimilarity with mycobacterial adjuvant in its mechanism of production of arthritis.

Food Chem Toxicol, 1988 Mar, 26(3), 209 - 14
Formation of a mutagenic diazoquinone by interaction of phenol with nitrite; Kikugawa K et al.; Reaction of phenol with nitrite under mildly acidic conditions produced p-nitrosophenol, p-diazoquinone and o-diazoquinone . p-Diazoquinone showed mutagenicity in Salmonella typhimurium strains TA98 and TA100 without metabolic activation; the number of his+ revertant colonies in strain TA98 was 85 with a dose of 20 nmol (after deduction of the background (control) number of about 20) . Higher doses of the compound were bactericidal . While the reaction of phenol with an equivalent amount of nitrite at pH 3 produced p-nitrosophenol in high yield, reaction with excess nitrite produced a high yield of p-diazoquinone . p-Nitrosophenol was converted to p-diazoquinone by reaction with nitrite . Formation of o-diazoquinone also increased with increasing amounts of nitrite . The formation of these compounds was not greatly affected by the presence of dimethylamine . Nitrosation of dimethylamine with nitrite was stimulated by phenol because of the formation of p-nitrosophenol and its stimulatory effect . Thus, the reaction of phenol with nitrite can produce mutagenic p-diazoquinone, and can also stimulate nitrosation of secondary amines by production of p-nitrosophenol.

Hinyokika Kiyo, 1988 Mar, 34(3), 473 - 7
{Two cases of acute renal failure associated with non-typhoid Salmonella infection}; Suzuki Y et al.; Two cases of acute renal failure associated with non-typhoid Salmonella infection are reported . Case 1: A 49-year-old man was admitted with the complaint of severe watery diarrhea and oliguria . Stool culture revealed Salmonella typhimurium . Laboratory data showed hyponatremia and acute renal failure . Hemodialysis was performed 3 times and renal failure was improved . Case 2: A 63-year-old woman was admitted with complaint of severe watery diarrhea, nausea, and fever . Stool culture revealed Salmonella E group . Septic shock appeared after admission, and anti-shock therapy was immediately carried out . Acute renal failure was cured without hemodialysis, even though multiple organ failure had occurred concomitantly . We discussed the management of patients with Salmonella infection, especially those with acute renal failure.

Mutagenesis, 1988 Mar, 3(2), 169 - 73
The bacterial mutagenicity of synthetic all-trans fecapentaene-12 changes when assayed under anaerobic conditions; Venitt S et al.; Fecapentaenes are potent mutagens produced in the anaerobic environment of the human colon . The aim of this study was to determine the effect of anaerobic conditions on the bacterial mutagenicity of all-trans fecapentaene-12, a synthetic fecapentaene . Fecapentaene-12 was tested aerobically and anaerobically at doses from 0.25 to 4 micrograms/plate in agar-overlay assays with Salmonella typhimurium TA98 and TA100 and Escherichia coli WP2uvrA(pKM101), and 0.01 to 2 micrograms/ml in fluctuation test with TA100 . In agar-overlay tests, fecapentaene-12 was less mutagenic to the frameshift mutant TA98 under aerobic conditions than under anaerobic conditions (average slopes of 3.8 and 31.6 revertants/micrograms respectively) . Aerobic assays using TA100 and E . coli WP2uvrA-(pKM101) gave respective slopes of 62.9 and 167.6 . Anaerobic assays with these base-substitution mutants gave negative results under conditions in which positive controls were mutagenic . However, the numbers of spontaneous revertants in these anaerobic assays were substantially lower than normal . Microtitre fluctuation tests, known to perform equally well under both aerobic and anaerobic conditions, were conducted with TA100 to confirm that the activity of fecapentaene-12 as a base-substitution mutagen was attenuated under anaerobic conditions . Replicate aerobic assays gave an average slope (revertants/well/microgram) of 0.41, compared with 0.056 for anaerobic assays--a greater than 7-fold difference . There was no significant difference in slope between aerobic and anaerobic positive controls . Thus, fecapentaene-12 may have two distinct modes of action, acting as a base-substitution mutagen and as a frameshift mutagen . Anaerobic conditions suppress the base-substitution activity but not the frameshift activity.(ABSTRACT TRUNCATED AT 250 WORDS)

Mutagenesis, 1988 Mar, 3(2), 137 - 40
Genotoxicity of 2-nitropropane and 1-nitropropane in Salmonella typhimurium and human lymphocytes; Goggelmann W et al.; A 10- and 12-fold increase of revertant numbers could be demonstrated for 2-nitropropane (2-NP of greater than 99% purity) tested in the preincubation assay with Salmonella typhimurium strains TA 100 and TA 98 in the presence and absence of S9 mix . In the nitroreductase-deficient strains TA 100NR and TA 98NR, 2-NP was less mutagenic than in the parent strains . In human lymphocytes the induction of a weak clastogenic effect and of sister chromatid exchanges required exogenous metabolic activation . No significant mutagenic or cytogenetic response was found with 1-nitropropane of 97% purity in S . typhimurium or human lymphocytes.

J Pharm Sci, 1988 Mar, 77(3), 259 - 64
Microbial transformation of the antihistaminic drug triprolidine hydrochloride; Hansen EB Jr et al.; The production of a known mammalian metabolite of the antihistamine triprolidine through fungal metabolic transformation has been demonstrated . The filamentous fungus Cunninghamella elegans ATCC 9245 was grown in Sabouraud dextrose broth containing triprolidine hydrochloride monohydrate . One major metabolite was extracted with methylene chloride, isolated by high-performance liquid chromatography, and identified by its proton-nuclear magnetic resonance and desorption chemical ionization mass spectral properties as hydroxymethyl triprolidine (2-{1-(4-hydroxymethylphenyl)-3-(1-pyrrolidinyl-1-propenyl)} pyridine) . After 240 h of incubation, the hydroxymethyl derivative represented approximately 55.0% of the initial dose . Fungal oxidation of hydroxymethyl triprolidine to the corresponding carboxylic acid triprolidine derivative (also a known mammalian triprolidine metabolite) was not observed . No mutagenic activity was observed for triprolidine and hydroxymethyl triprolidine by reversion of Salmonella typhimurium strains TA97, TA98, TA100, and TA104 at concentrations up to 1000 and 200 micrograms/plate, respectively . These results suggest that the fungal metabolism of triprolidine to the hydroxymethyl derivative occurs predominantly through pathways which do not result in mutagenic activation . Incubation of C . elegans with triprolidine under an 18O2 atmosphere and subsequent electron impact mass spectral analysis of the hydroxymethyl triprolidine formed indicate that molecular oxygen was incorporated into the methyl group and suggest a mono-oxygenase catalyzed reaction . This study parallels previous studies on the mammalian metabolism of triprolidine and clearly indicates that the microbial transformation of triprolidine is a useful alternative for the synthesis of potential mammalian metabolites.

Mutat Res, 1988 Mar-Apr, 207(3-4), 205 - 12
Mutagenicity of naphthacene, a non-bay-region aromatic hydrocarbon, in Salmonella; Pahlman R; Naphthacene (2,3-benzanthracene, tetracene) was tested for mutagenicity towards Salmonella typhimurium strains TA1535, TA1537, TA1538, TA98 and TA100 . Mutagenicity was seen in all strains except in TA1535 when liver S9 fraction from rats or mice was present . The increases in the number of revertants induced by naphthacene equalled those by other naturally occurring polycyclic aromatic hydrocarbons, benzo{a}pyrene and dibenz{ac}anthracene, in the strains TA98 and TA100.

Mutat Res, 1988 Mar, 198(1), 1 - 8
DNA binding and mutagenicity of ethyl methanesulfonate in wild-type and uvrB cells of Salmonella typhimurium; Matijasevic Z et al.; The extent of DNA ethylation and the influence of excision repair on ethyl methanesulfonate (EMS) mutagenesis of Salmonella typhimurium were examined . The relationship between the dose to DNA and the exposure concentration of EMS was linear . EMS induction of his+ revertants followed exponential kinetics and did not parallel the increase in total DNA ethylation . Mutant induction was influenced by the cells' nucleotide excision repair ability . Although mutagenized to a larger extent than the wild-type (uvr+) strain at high doses, the uvrB strain was more resistant to the mutagenic effect of low doses of EMS.

J Med Microbiol, 1988 Mar, 25(3), 221 - 5
Abortive phage-infection and UV-protection markers on Col I plasmids from epidemic strains of Salmonella; Barker RM; Cultures of Escherichia coli carrying ColI plasmids received in conjugation from strains of Salmonella typhimurium and S . agona were examined for abortive infection (Abi) of phage BF23 and for enhanced resistance to the lethal action of UV-irradiation (Uvr) . The Abi character of stored cultures of E . coli was also compared with the reaction of the same stock culture tested 5 years before . Seven of the eight potential types differentiated by three characters were represented among 160 ColI plasmids: ColIa Abi+ Uvr+ (3 plasmids), ColIa Abi- Uvr+ (1), ColIa Abi- Uvr- (2), ColIb Abi+ Uvr+ (85), ColIb Abi+ Uvr- (5), ColIb Abi- Uvr+ (4), ColIb abi- Uvr- (60) . Recognition that different plasmid types could be carried by strains of a clone proved useful in the interpretation of the epidemic spread of strains of S . typhimurium of phage type/biotype 141/9f in Scotland and in tracing the ancestry of a recently emerged rhamnose non-fermenting mutant strain of S . agona.

J Immunol, 1988 Mar 1, 140(5), 1638 - 44
Induction of activated macrophages in C3H/HeJ mice by avirulent Salmonella; Schafer R et al.; A single injection of viable Salmonella typhimurium SL3235, an avirulent organism blocked in the aromatic pathway, induced the generation of activated peritoneal macrophages in three different C3H mouse strains, including macrophage-defective C3H/HeJ mice . Macrophages obtained from immunized mice were cytotoxic for B16 melanoma cells, P815 mastocytoma cells, and TU-5 fibrosarcoma cells and microbicidal in vitro for the obligate, intracellular, protozoan parasite Leishmania major . The capacity of live SL3235 to activate C3H/HeJ macrophages contrasts with the failure of live Bacillus Calmette-Guerin to induce activated macrophages in this mouse strain . Although viable SL3235 were capable of fully activating cells of both normal and defective mice, a dose-dependent difference was observed in the number of organisms necessary for induction of tumoricidal macrophages in C3HeB/FeJ (normal) and C3H/HeJ (defective) animals . As few as 80 viable SL3235 were capable of activating C3HeB/FeJ macrophages whereas 5 X 10(4) organisms were required to activate C3H/HeJ macrophages . Maximal macrophage activation occurred 7 to 10 days after SL3235 inoculation in C3H/HeJ and C3HeB/FeJ mice . Acetone-killed cells of SL3235 had some but not all of the activity of the living Salmonella . A single in vivo injection of the nonviable preparation resulted in the induction of tumoricidal macrophages in C3HeB/FeJ but not in C3H/HeJ mice, even when tested over a wide dosage range . Injection of acetone-killed cells of SL3235 did, however, result in a population of primed macrophages in C3H/HeJ mice, as explanted cells could be induced to express activated macrophage effector activities after additional treatment in vitro with either LPS or IFN-gamma . Thus, in vivo administration of viable SL3235 is, by itself, capable of eliciting the full series of steps required for activation of C3H/HeJ macrophages, whereas killed SL3235 only provides signals sufficient to prime these defective macrophages for further activation in vitro . AI 15613

Arch Dermatol, 1988 Mar, 124(3), 396 - 8
Dinitrochlorobenzene is inherently mutagenic in the presence of trace mutagenic contaminants; Wilkerson MG et al.; 2,4-Dinitrochlorobenzene (DNCB) is used for immunotherapy of alopecia areata and verruca vulgaris . We initially postulated that the presence of mutagenic contaminants in commercially available DNCB might account for part of its mutagenicity . We have now characterized changes in the dose-mutagenic response curve of 99% DNCB modified by adding 1% concentrations of known contaminants: 1-chloro-2-nitrobenzene; 1,3-dinitrobenzene; and 2,4-dichloronitrobenzene . Dose-response curves were generated using Salmonella typhimurium tester strains TA-98 and TA-100 at concentrations of 0, 1, 5, 10, 25, 50, and 100 micrograms per plate in a modified Ames assay . We observed a linear dose-response relationship with a slight, but nonsignificant, shift to the right when contaminants were added . We conclude that DNCB is itself mutagenic, and that contaminants play a minor role in its observed mutagenicity.

Proc Natl Acad Sci U S A, 1988 Mar, 85(5), 1403 - 7
CheA protein, a central regulator of bacterial chemotaxis, belongs to a family of proteins that control gene expression in response to changing environmental conditions; Stock A et al.; During bacterial chemotaxis, the binding of stimulatory ligands to chemoreceptors at the cell periphery leads to a response at the flagellar motor . Three proteins appear to be required for receptor-mediated control of swimming behavior, the products of the cheA, cheW, and cheY genes . Here we present the complete nucleotide sequence of the Salmonella typhimurium cheA gene together with the purification and characterization of its protein product . The protein is a 73,000 Mr cytoplasmic constituent . Amino acid-sequence comparisons indicate that it belongs to a family of bacterial regulatory proteins including the products of the cpxA, dctB, envZ, ntrB, phoR, phoM, and virA genes . Each member of this family has a conserved domain of approximately equal to 200 residues within its C terminus . We have previously shown that another chemotaxis protein, CheY, represents a domain of protein structure that has been conserved within a second large family of bacterial regulatory proteins . Each protein of the CheA family seems to function as a regulator of a different CheY homologue . Although each pair of proteins appears to produce a specialized response to a distinct type of stimulus, the relationships in primary structure suggest that a similar molecular mechanism may be involved.

Mutagenesis, 1988 Mar, 3(2), 147 - 52
Synthesis and mutagenic activity of nitro-imidazoarenes . A study on the mechanism of the genotoxicity of heterocyclic arylamines and nitroarenes; Dirr A et al.; A series of nitro-imidazoarenes (nitro-IAs) were synthesized from the corresponding amino-imidazoarenes (amino-IAs) . These two classes of compounds are structurally related to the potent food mutagen and carcinogen, 2-amino-3-methylimidazo{4,5-f}quinoline (IQ) . The mutagenic activities of the nitro-IAs were assayed in the Salmonella typhimurium frameshift tester strains TA98, TA98/1,8-DNP6 and TA98NR without use of extracellular metabolization . Nitro-IQ, the nitro counterpart of IQ, was two times more mutagenic than IQ . In general, the mutagenic activities of the nitro-IAs varied over 50,000-fold . The relationships between the chemical structures and mutagenic activities are identical with those previously reported for the corresponding amino-IAs: the methyl group on the imidazole ring and the quinoline-nitrogen were found to be required for potent mutagenic activity . The reductive activation of the nitro-IAs is not carried out primarily by the 'classical' nitroreductase of Salmonella which is defective in TA98NR . The O-acetyltransferase defective in TA98/1,8-DNP6 is required for the efficient production of the ultimate mutagens of the nitro-IAs . The interchangeability of the structure-activity relationships of the nitro-IAs and amino-IAs reflects a basic similarity of the mechanisms of the mutagenicity of the two classes of compounds . It is likely that N-hydroxy compounds are proximate metabolites common to the nitro-IAs and amino-IAs; they are further activated by an acetyl-CoA-dependent O-acetyltransferase of Salmonella . It is very likely a property of the ultimate mutagen, possibly a nitrenium ion, which governs the mutagenic potency of the different nitro- and amino-IAs and thus determines the structure-activity relationships.

J Bacteriol, 1988 Mar, 170(3), 1076 - 81
Unmasking of bacteriophage Mu lipopolysaccharide receptors in Salmonella enteritidis confers sensitivity to Mu and permits Mu mutagenesis; Muller KH et al.; The human pathogen Salmonella enteritidis 3b was found to be highly resistant to phage P22 and Mu derivatives . The Mu sensitivity (musA1) allele from Salmonella typhimurium could be transferred to S . enteritidis 3b at low frequency by cotransduction with hisG::Tn10 . Sensitivity to Mu resulted in a large reduction in the number of lipopolysaccharide core-region oligosaccharides that were substituted with O-antigen polysaccharide . The residual high-molecular-weight lipopolysaccharide appeared to be a hybrid displaying O antigens which were immunologically related to those of S . typhimurium and not to those of S . enteritidis . Consequently, Mu d1(Ap lac) could then be transduced into Mus strains forming stable lysogens . On temperature induction, Mu transposition could easily be used to generate mutations in genes coding for cell surface antigens including fimbriae, lipopolysaccharide, and flagella.

Mutat Res, 1988 Mar-Apr, 207(3-4), 99 - 105
Antimutagenic effects of chemicals on mutagenesis resulting from excision of a transposon in Salmonella typhimurium; MacPhee DG et al.; We have found that a temperature-sensitive mutation in the polA gene of Salmonella typhimurium strain LT2 causes precise excision of transposon Tn10 to occur at significantly increased frequencies in cells incubated at the restrictive temperature . In our experiments, precise excision from a site in the tryptophan operon was measured by determining the frequency of reversion of the auxotrophic trp1014::Tn10 polA7 strain to prototrophy on defined medium containing a trace amount of broth . Because the yields of revertants at 37 degrees C were of the order of 200 colonies per plate, it was possible to measure the effects of chemical inhibitors on the processes involved in precise excision . We now report that all of the DNA-repair inhibitors we have studied (caffeine, ethionine, acriflavine, procaine and cinnamaldehyde) are effective inhibitors of precise excision of Tn10, and can therefore be defined as antimutagens.

Eur J Epidemiol, 1988 Mar, 4(1), 110 - 4
Porin content modifies resistance of Salmonella typhimurium to phagocytosis; Tufano MA et al.; Mutants of Salmonella typhimurium, which contain different quantities of outer membrane proteins, show different susceptibility to phagocytosis . We correlate susceptibility to phagocytosis with molecular surface characteristics which are responsible for invasiveness and virulence of bacteria.

J Bacteriol, 1988 Mar, 170(3), 1063 - 8
Effect of lipopolysaccharide structure on reactivity of antiporin monoclonal antibodies with the bacterial cell surface; Bentley AT et al.; We studied the reactivity of 66 anti-Escherichia coli B/r porin monoclonal antibodies (MAbs) with several E . coli and Salmonella typhimurium strains . Western immunoblots showed complete immunological cross-reactivity between E . coli B/r and K-12; among 34 MAbs which recognized porin in immunoblots of denatured outer membranes of E . coli B/r, all reacted with OmpF in denatured outer membranes of E . coli K-12 . Extensive reactivity, although less than that for strain B/r (31 of 34 MAbs), occurred for porin from a wild-type isolate, E . coli O8:K27 . Only one of the MAbs reacted with porin in denatured outer membranes of S . typhimurium . Even with immunochemical amplification of the Western immunoblot technique, only six MAbs recognized S . typhimurium porin (OmpD), demonstrating that there is significant immunological divergence between the porins of these species . Antibody binding to the bacterial surface, which was analyzed by cytofluorimetry, was strongly influenced by lipopolysaccharide (LPS) structure . An intact O antigen, as in E . coli O8:K27, blocked adsorption of all 20 MAbs in the test panel . rfa+ E . coli K-12, without an O antigen but with an intact LPS core, bound seven MAbs . When assayed against a series of rfa E . coli K-12 mutants, the number of MAbs that recognized porin surface epitopes increased sequentially as the LPS core became shorter . A total of 17 MAbs bound porin in a deep rough rfaD strain . Similar results were obtained with S . typhimurium . None of the anti-E . coli B/r porin MAbs adsorbed to a smooth strain, but three antibodies recognized porin on deep rough (rfaF, rfaE) mutants . These data define six distinct porin surface epitopes that are shielded by LPS from reaction with antibodies.

Biochemistry, 1988 Feb 23, 27(4), 1125 - 31
A new synthesis of adenosine 5'-({gamma(R)-17O,18O}-gamma-thiotriphosphate) and its use to determine the stereochemical course of the activation of glutamate by glutamine synthetase; Bethell RC et al.; A new synthetic route to adenosine 5'-({gamma(R)-17O,18O}-gamma-thiotriphosphate) is described which combines chemical methods for introducing the heavy oxygen isotopes and enzymic methods for achieving the enantiospecificity . This material was used as a substrate for the activation of glutamate catalyzed by glutamine synthetase from Salmonella typhimurium . Analysis of the chirality of the {16O,17O,18O}thiophosphate produced showed that the reaction proceeds with inversion of configuration on phosphorus . This result, taken together with the positional isotope exchange studies of Midelfort and Rose {Midelfort, C . F., & Rose, I.A . (1976) J . Biol . Chem . 251, 5881-5887}, demonstrates that the activation of glutamate to form gamma-glutamyl phosphate proceeds by a direct "in-line" transfer of the phosphoryl group.

J Am Vet Med Assoc, 1988 Feb 15, 192(4), 527 - 9
Septicemic salmonellosis and suspected phenylbutazone toxicosis in an aged pony; Hondalus MK et al.; A 16-year-old pony with signs of intermittent abdominal pain was treated with phenylbutazone in excess of the recommended dosage . Endoscopy revealed ulceration of the esophagus, stomach, and proximal portion of small intestine . The pony developed diarrhea . Salmonella typhimurium was isolated from the blood and feces . Treatment included fluids, trimethoprim-sulfadiazine, sucralfate, and ranitidine hydrochloride . The diarrhea resolved, as did the gastrointestinal ulceration . This case was unusual because septicemia with salmonellosis is an uncommon finding in adult equids . Also, complications commonly seen in neonatal septicemia (septic arthritis, nephritis, and hepatitis) were not observed . Phenylbutazone toxicosis and stress were considered possible causes for the gastrointestinal ulceration.

Cancer Res, 1988 Feb 15, 48(4), 907 - 12
L-arabinose resistance test with Salmonella typhimurium as a primary tool for carcinogen screening; Dorado G et al.; The L-arabinose resistance test with Salmonella typhimurium (Ara test) is a forward mutation assay which selects a single phenotypic change (from L-arabinose sensitivity to L-arabinose resistance) in a unique tester strain (an araD mutant) . The present study examined the ability of the Ara test to identify as mutagens different classes of chemical carcinogens, including six with detection problems in most bacterial assays . A noncarcinogen related in chemical structure to the selected carcinogen was included whenever possible . A total of 25 organic compounds was assayed by means of a standard mutagenesis procedure: the plate-incorporation test in the presence (if required) of 10% S9 from rat liver induced with Aroclor 1254 . Chemicals giving negative or inconclusive results were then retested using other common in vitro mutagenesis conditions . The Ara test detected as mutagens all but one (Urethane) of the 15 established carcinogens and six out of the nine chemicals with questionable or nonassayed carcinogenicity . The compound mutagenic at the lowest dose was ethionine (0.57 nmol), one of the carcinogens undetected by the popular histidine reverse mutation assay (Ames test) or by the SOS chromotest . Actually, only benzo(a)pyrene was found mutagenic at a dose (0.77 nmol) close to that of ethionine . The data reported in this paper suggest that the Ara forward mutation test is less prone than the His reverse mutation test or the SOS chromotest to misclassify as negative carcinogenic compounds . Consequently, it should be considered as an alternative to other bacterial assays in general, massive, and primary screening for genotoxic carcinogens.

Biochem Pharmacol, 1988 Feb 15, 37(4), 577 - 81
Biochemical characterization of glutathione-deficient mutants of Escherichia coli K12 and Salmonella strains TA1535 and TA100; Bouter S et al.; Glutathione-deficient mutants of Escherichia coli K12/343/408 and Salmonella typhimurium TA1535 and TA100 were characterized biochemically by measuring the rate of formation of (14C)gamma-glutamylcysteine and (14C)glutathione in cell-free extracts of the strains . gamma-Glutamylcysteine synthetase activity was found to be absent in the NGR-2 mutant of E . coli and in the Salmonella mutants TA1535/NG-19, TA100/NG-57 and TA100/NG-11, while only low activities were found in the NGR-9 and NG-54 mutant of E . coli and Salmonella respectively . These results correspond with the decreased levels of glutathione found in these strains . Extracts of the parent strains have normal glutathione levels and show high gamma-glutamylcysteine synthetase activities . It is concluded that the present GSH-deficient strains of E . coli and Salmonella are gshA mutants, analogous to those previously described in E . coli . In addition, the present results show that the fluorometric method used for the determination of glutathione, employing o-phthalaldehyde as a reagent, is not specific for glutathione (at pH 8.0), but also sensitively reacts with gamma-glutamylcysteine.

Mutat Res, 1988 Feb, 197(2), 289 - 302
Metabolism of mutagenic polycyclic aromatic hydrocarbons by photosynthetic algal species; Schoeny R et al.; Polycyclic aromatic hydrocarbons (PAH) known to produce carcinogenic and mutagenic effects have been shown to contaminate waters, sediments and soils . While it is accepted that metabolites of these compounds are responsible for most of their biological effects in mammals, their metabolism, and to a large extent their bioactivity, in aquatic plants have not been explored . Cultures of photosynthetic algal species were assayed for their ability to metabolize benzo{a}pyrene (BaP), a carcinogenic PAH under conditions which either permitted (white light) or disallowed (gold light) photooxidation of the compound . Growth of Selenastrum capricornutum, a fresh-water green alga, was completely inhibited when incubated in white light with 160 micrograms BaP/l medium . By contrast concentrations at the upper limit of BaP solubility in aqueous medium had no effect on algal growth when gold light was used . BaP quinones and phenol derivatives were found to inhibit growth of Selenastrum under white light incubation . BaP phototoxicity and metabolism were observed to be species-specific . All 3 tested species of the order Chlorococcales were growth-inhibited by BaP in white light whereas neither the green alga Chlamydomonas reinhardtii nor a blue-green, a yellow-green or an euglenoid alga responded in this fashion . Assays of radiolabeled BaP metabolism in Selenastrum showed that the majority of radioactivity associated with BaP was found in media as opposed to algal cell pellets, that the extent of metabolism was BaP concentration dependent, and that the proportion of various metabolites detected was a function of the light source . After gold light incubation, BaP diols predominated while after white light treatment at equal BaP concentrations, the 3,6-quinone was found in the highest concentration . Extracted material from algal cell pellets and from media was tested for mutagenicity in a forward mutation suspension assay in Salmonella typhimurium using resistance to 8-azaguanine for selection . Direct-acting mutagens were detected in extracted media from incubation of Selenastrum with 400 micrograms BaP/l for 1 day in gold light . Extracts of media from algae incubated in gold light from 1 to 4 days with 1200 micrograms BaP/l were found to have direct-acting mutagens as well as those requiring further metabolism . Media extracts from white light incubations of BaP were mutagenic upon addition of rat liver homogenates . Activity of these materials from white light treatment are largely attributable to unmetabolized BaP.

Carcinogenesis, 1988 Feb, 9(2), 255 - 8
Metabolism of K-region derivatives of 1-nitropyrene by rat liver in vitro; Roy AK et al.; The metabolism of K-region derivatives of 1-nitropyrene was studied in order to provide insight into factors that may contribute to their mutagenic activities and to obtain information on unknown metabolites of 1-nitropyrene . Using 9000 g supernatant from livers of Aroclor-treated rats, 1-nitro-pyrene-4,5-diol, a mutagenic metabolite of 1-nitropyrene, was metabolized to 1-aminopyrene-4,5-diol, a mixture of 1-nitropyrene-4,5,9,10-tetraols, 1-amino-4,5-pyrenedione and 1-nitro-4,5-pyrenedione . 1-Nitro-5H-phenanthro{4,5-bcd}pyran-5-one, a highly mutagenic lactone, was not detected . The metabolism of 1-nitro-4,5-pyrenedione yielded only 1-amino-4,5-pyrenedione; the lactone was not observed . No metabolites were detected when the lactone was incubated under conditions identical to those employed for 1-nitro-4,5-diol and 1-nitro-4,5-pyrenedione . Upon re-examination of the metabolism of 1-nitropyrene, we were able to detect 1-nitropyrene-4,5,9,10-tetraol, 1-amino-4,5-pyrenedione and 1-nitro-4,5-pyrenedione as minor metabolites in addition to the major metabolites reported previously . The results of this study, combined with the mutagenicity data for the K-region derivatives of 1-nitropyrene, suggest that nitroreduction of 1-nitropyrene-4,5-diol and 1-nitro-4,5-pyrenedione to the corresponding hydroxylamines is an important pathway for their metabolic activation in Salmonella typhimurium and their metabolic activation in Salmonella typhimurium and possibly in mammalian systems.

Biochem Pharmacol, 1988 Feb 1, 37(3), 459 - 65
Metabolic activation of environmental carcinogens and mutagens by human liver microsomes . Role of cytochrome P-450 homologous to a 3-methylcholanthrene-inducible isozyme in rat liver; Shimada T et al.; The metabolic activation of procarcinogens and promutagens by human liver microsomal cytochrome P-450 has been investigated by means of a newly developed method measuring the induction of umu gene in Salmonella typhimurium TA1535/pSK1002 {T . Shimada and S . Nakamura, Biochem . Pharmac . 36, 1979 (1987)} . The chemicals examined were aflatoxin B1 (AFB1), eight carcinogenic heterocyclic aromatic amines isolated from protein and amino acid pyrolysates, and 2-aminoanthracene . Liver microsomes from six patients catalyzed the metabolic activation of these chemicals; 2-amino-3,5-dimethylimidazo{4,5-f}quinoline (MeIQ) and AFB1 were most actively bioactivated, followed by 2-amino-3-methylimidazo{4,5-f}quinoline (IQ), 2-aminoanthracene (2-AA) and 2-amino-3,8-dimethylimidazo{4,5-f}quinoxaline . At least two forms of human cytochrome P-450 may be involved in the activation of these procarcinogens . This suggestion was supported by the following lines of evidence: (a) addition of non-ionic detergent Emulgen 913 to the incubation mixture caused a more profound inhibition of microsome-catalyzed activation of AFB1 than of MeIQ, IQ and 2AA, (b) 7,8-benzoflavone stimulated the activation of AFB1 by about 2.5-fold, whereas it inhibited significantly the reactions with MeIQ, IQ and 2AA, and (c) polyclonal antibodies against a 3-methylcholanthrene-inducible form of rat cytochrome P-450 (P-450d) caused a marked inhibition of the metabolic activation of MeIQ, IQ and 2-AA by human liver microsomes though they did not show any effects on the microsomal activation of AFB1 . Data are also presented showing that none of the reactions catalyzed by human liver microsomes were inhibited by antibodies to a phenobarbital-inducible form of rat cytochrome P-450 (P-450b) . These results suggest that the human cytochrome P-450 isozyme that is immunochemically similar and, thus, homologous to rat P-450d plays a major role in the metabolic activation of several procarcinogens examined, and that the activation of AFB1 is catalyzed by another and, possibly, not phenobarbital-inducible form(s) of human cytochrome P-450.

Zh Mikrobiol Epidemiol Immunobiol, 1988 Feb, (2), 118 - 21
{The role of IgM in paratyphoid immunity}; Peshkus IuK et al.; The authors analyze the results of studies on the effect produced by the immunization of calves with paratyphoid vaccine on the production of agglutinins, changes in the blood serum immunoglobulin levels, and the specificity of IgM to Salmonella dublin and Salmonella typhimurium antigens . The highest level of agglutinins to paratyphoid antigens in the blood sera of the immunized calves was registered on days 14-21 after immunization, changes in the levels of different immunoglobulin classes being insignificant . The agglutination test and the enzyme immunoassay have revealed that antibodies to S . dublin anb S . typhimurium antigens belong to IgM.

Mutat Res, 1988 Feb, 204(2), 207 - 17
Comparison of the mutagenicity of amsacrine with that of a new clinical analogue, CI-921; Ferguson LR et al.; The mutagenicity of CI-921, the 4-methyl-5-(N-methyl)carboxamide derivative of the clinical antileukaemia agent, amsacrine, has been assessed using both bacterial and mammalian cells . CI-921 is distinguished from amsacrine in its high activity against some experimental tumours and is currently undergoing phase I clinical trial . Like 9-aminoacridine and amsacrine, CI-921 is mutagenic to the Salmonella typhimurium frameshift tester strain TA1537, but shows no sign of inducing base pair changes in strain TA100 . In Chinese hamster cell culture, however, it differs from 9-aminoacridine in causing extensive chromosomal aberrations and an increase in mutations at the hypoxanthine-guanine phosphoribosyltransferase locus . It induces the formation of tightly packed and multilayered colonies in treated cultures of C3H/10T1/2 cells, but its action differs from that of benzo{a}pyrene, which induces type III fibroblastic multilayered colonies . Side-by-side comparison of the mutagenic properties of CI-921 and amsacrine showed no substantial differences at similar toxicity, suggesting that the increased lipophilicity and DNA-binding affinity of CI-921, which are thought to contribute to its increased antitumour activity, do not concomitantly increase the efficiency of in vitro mutagenesis or cell transformation.

Mutat Res, 1988 Feb, 204(2), 185 - 93
Activation of the food-derived mutagen 2-amino-3-methylimidazo{4, 5-f}quinoline by human-liver microsomes; McManus ME et al.; The ability of human-liver microsomes to metabolically activate the food-derived heterocyclic amine, 2-amino-3-methylimidazo{4,5-f}quinoline (IQ), and the model mutagen, 2-aminofluorene (AF), has been investigated using Salmonella typhimurium TA98 . In 6 subjects tested the number of revertants produced by 0.1 micrograms IQ per mg microsomal protein varied from 11, 830 +/- 320 to 42, 830 +/- 290 (mean +/- SD) . With the same livers and a dose of 10 micrograms AF per plate the number of revertants varied from 15,770 +/- 1600 to 29,380 +/- 810 per mg microsomal protein . Metyrapone and alpha-naphthoflavone caused differential inhibition of the mutagenesis of both IQ and AF indicating the involvement of different forms of cytochrome P450 in the metabolic activation of these amines in human-liver microsomes . In presence of human-liver microsomes IQ produced no detectable increase in mutations at the hypoxanthine phosphoribosyl transferase locus in lymphocytes and caused no increase in micronuclei formation at realistic exposure levels.

Mutat Res, 1988 Feb, 204(2), 123 - 9
Mutagenicity of methyl isocyanate in the modified test conditions of Ames Salmonella/microsome liquid-preincubation procedure; Meshram GP et al.; Methyl isocyanate (MIC) was tested for mutagenicity using the Ames Salmonella/microsome liquid-preincubation procedure with slight modification of test conditions . In the modification the preincubation mixture was incubated at 10 degrees C for 60 min . MIC was assayed both in the presence and absence of Aroclor-1254-induced S9, using 5 tester strains of Salmonella typhimurium, TA97a, TA98, TA100, TA102 and TA104 . MIC induced mutagenic response in two base-pair substitution strains, TA100 and TA104, in the presence and absence of S9 . However, mutagenic response in the presence of S9 was low as compared to that in the absence of S9 . In the comparative mutagenic activity at 3 different preincubation test conditions (37 degrees C for 20 min, 20 degrees C for 40 min and 10 degrees C for 60 min), optimum mutagenic response was observed at 10 degrees C for the 60-min test condition . However, no mutagenic response was observed at 37 degrees C for the 20-min test condition.

Mutat Res, 1988 Feb, 204(2), 117 - 21
Inverse correlation between combined mutagenicity in Salmonella typhimurium and strength of coordinate bond in mixtures of cobalt(II) chloride and 4-substituted pyridines; Ogawa HI et al.; Cobalt(II) chloride (CoCl2), non-mutagenic by itself, has been tested for mutagenic activity in the presence of 4-substituted pyridines in the test strains of Salmonella typhimurium . CoCl2 was found to be mutagenic in strains TA1537 and TA2637, when combined pyridine, with methyl isonicotinate, 4-methyl-pyridine, 4-ethylpyridine, 4-chloropyridine or 4-bromopyridine . Mixtures of CoCl2 and isonicotinic acid, 4-cyanopyridine, 4-aminopyridine, or 4-dimethylaminopyridine exhibited no mutagenicity . Judging from the spectral observations, such combined mutagenicity may be due to the formation of moderate to weak complexes between these compounds and the Co(II) cation.

Toxicol Lett, 1988 Feb, 40(2), 183 - 92
Mutagenic activity of some textile dyes in different test systems; Przybojewska B et al.; The Salmonella/microsome mammalian test, the micronucleus and the dominant lethal tests on mice were used to study mutagenic effects of three dyes widely used in the textile industry . Direct Black 19:1, Direct Red 81 and Acid Blue 62 increased the frequency of micronucleated polychromatic erythrocytes in bone marrow of mice . Out of all dyes tested, only Direct Black 19:1 appeared to be an indirect mutagen inducing reverse mutations in two strains of Salmonella typhimurium TA 1538 and TA 98 . None of them produced dominant lethal mutations in germ cells of male mice.

Toxicol Appl Pharmacol, 1988 Feb, 92(2), 286 - 94
Detection and mechanism of formation of the potent direct-acting mutagen 2-bromoacrolein from 1,2-dibromo-3-chloropropane; Omichinski JG et al.; The nematocide 1,2-dibromo-3-chloropropane (DBCP) was converted to products which are mutagenic for Salmonella typhimurium TA 100 in the presence of rat liver microsomes, NADPH, and oxygen . Typical in vivo and in vitro inhibitors of cytochrome P-450 decreased DBCP mutagenicity in the presence of microsomes . Addition of glutathione to cytosolic preparations failed to bioactivate DBCP to mutagenic metabolites . Mutagenicity studies with selectively deuterated analogs showed that substitution of deuterium for hydrogen at C-1 or C-3 of DBCP modestly decreased mutagenicity, but that deuteration at both C-1 and C-3 markedly decreased mutagenicity . The formation rates of the potent direct-acting mutagen, 2-bromoacrolein (2-BA), in incubations of DBCP and its deuterated analogs with rat liver microsomes, correlated with the isotope effects on mutagenicity . Characterization of 2-BA was accomplished by gas chromatography-mass spectrometry using positive-ion chemical ionization . Mass spectral analysis of 2-BA formed from specifically deuterated analogs of DBCP indicated that initial oxidative dehalogenation at C-1 followed by a spontaneous beta-elimination reaction was the preferred pathway in the formation of 2-BA from DBCP . These results demonstrate that mutagenic metabolites of DBCP are formed by cytochrome P-450-mediated oxidative metabolism, and that 2-BA is a major mutagen formed.

Mutat Res, 1988 Feb, 203(1), 39 - 45
Response of the L-arabinose forward mutation assay of Salmonella typhimurium to frameshift-type mutagens; Hera C et al.; The present study was designed to evaluate the capacity of the L-arabinose resistance test of Salmonella typhimurium in the detection of frameshift-type mutagens . To this end the response of the Ara test was examined with respect to 15 chemicals which had been previously described as able to revert the Ames tester strain TA97 . The mutagenicity of each compound was determined by the liquid test under experimental conditions which optimize the mutagenic response of the Ara test with the tester strain BA9 . Strain TA97 was used simultaneously with BA9 . The Ara forward-mutation assay efficiently detected the mutagenic activity of 14 out of the 15 chemicals assayed . PR toxin was the only compound which gave a weak dose response without doubling the spontaneous mutant level . In comparison with the Ara test, a total of 3 chemicals (HZ, PE and PR toxin) were not found to be mutagenic with strain TA97 . In most cases (11/15) the mutagenic response of the Ara test was comparatively greater than that of strain TA97 . Three chemicals (DEO, PRF and 9-AA) were detected with quite similar degrees of sensitivity by both mutation assays . ICR-191, which seems highly specific in reverting frameshift mutations with added cytosines in a run of cytosines, was the only chemical with a lower mutagenic activity in the Ara test than in strain TA97 . The results enhance the interest of the L-arabinose forward-mutation assay as an alternative to the set of specific tester strains used by the histidine reverse-mutation assay in massive, general and primary screening for genotoxic agents.

Mutat Res, 1988 Feb, 197(2), 303 - 12
The plant activation of m-phenylenediamine by Tradescantia clone 03 and clone 4430 cells in liquid suspension culture; Anderson VA et al.; In this study, we expanded the use of the genus Tradescantia to investigate the plant activation of promutagens and further refine the methodology of the plant cell/microbe coincubation assay . Liquid suspension cell cultures of Tradescantia clone 03 and Tradescantia clone 4430 were used to activate the promutagen m-phenylenediamine into a mutagenic compound which was detected by Salmonella typhimurium strain TA98 in the plant cell/microbe coincubation assay . Optimum treatment parameters were established for both plant cell lines . Optimum was defined as the lowest concentration or shortest time period that provided consistently positive results and high rates of revertants . Preliminary experiments with both cell lines defined 2.5 mumoles m-phenylenediamine per plate as the optimum concentration to be used in the determination of the optimal coincubation period and the optimal concentration of plant cells . These experiments also determined the optimal physiological stage at which both clones should be used in the coincubation assay . Differences were found in the optimal of coincubation (1h for clone 03, 2 h for clone 4430) and growth stage (mid-log for clone 03, mid- to late-log for clone 4430) . Similar activation responses were seen for both clones when the concentration of plant cells (mg/ml) was varied . Under optimized conditions, clone 03 cells demonstrated an approximately 10% higher activation response than clone 4430.

Mutat Res, 1988 Feb, 197(2), 207 - 19
The plant cell/microbe coincubation assay for the analysis of plant-activated promutagens; Plewa MJ et al.; The preincubation and suspension procedures of the plant cell/microbe coincubation assay are described and the activation of 2-aminofluorene and m-phenylenediamine by cultured tobacco, cotton, carrot and maize cells is compared . The assay measures the plant activation of promutagens into genotoxins detected in Salmonella typhimurium as well as toxicity in plant and microbial cells . At concentrations of 2-aminofluorene 0-0.5 mumoles/reaction tube, the rank order of the efficiency of activation by plant cells was tobacco much greater than cotton greater than carrot . Cultured maize cells did not activate 2-aminofluorene . The tobacco cell activation of 2-aminofluorene was inhibited 50% by 750 microM diethyldithiocarbamate under conditions that did not affect the cell viability . Tobacco cells were also the most efficient plant cells in activating m-phenylenediamine (0-5 mumoles/reaction tube) . The 'biological affinity' of m-phenylenediamine for the activation system in tobacco cells was approximately 100 microM.

J Med Microbiol, 1988 Feb, 25(2), 139 - 46
Expression of an antigen in strains of Salmonella typhimurium which reacts with antibodies to cholera toxin; Clarke GJ et al.; Six strains of Salmonella typhimurium (W118, TML, SL1027, LT7, M206 and Thax 1) of different virulence were examined for the presence of antigens which react with antibodies to cholera toxin (anti-CT) . A fluorescent-antibody-labelling technique employing anti-CT was used to analyse antigen expression . A rapid increase in the proportion of cells producing a CT-related antigen was demonstrated in cells in early log phase (1-4 h growth) followed by a rapid decline during mid-late log phase in each of the six strains . The nature of the CT-related antigen was analysed by immunoblotting using anti-CT . An antigen of mol . wt equivalent to a high-mol . wt species of CT B subunit was detected in polymyxin-B extracts of all strains but greater amounts were observed in the strains that we consider avirulent . Nothing equivalent to a CT A-related subunit was observed in any of the strains . The relatedness of the salmonella antigen to CT was limited . The high-mol . wt antigen was not disrupted in the denaturing conditions of SDS-PAGE; nothing was detected by enzyme-linked immunosorbent assays with either ganglioside or anti-CT as anchor.

J Bacteriol, 1988 Feb, 170(2), 842 - 51
Novel regulatory loci controlling oxygen- and pH-regulated gene expression in Salmonella typhimurium; Aliabadi Z et al.; Three new loci were discovered, each of which participates in the regulation of anaerobic gene expression . The regulatory gene earA negatively regulates the expression of the anaerobiosis-inducible gene aniG as well as that of at least three other genes, as determined by two-dimensional polyacrylamide gel electrophoresis . The earA locus maps at 86 min . The expression of aniG was also shown to be controlled by changes in external pH under aerobic and anaerobic conditions . Maximal expression was observed under anaerobic conditions at an external pH of 6.0 . Significant transcriptional activity was also observed under aerobic conditions at pH 6.0 . This was in contrast to hyd, whose expression was dependent upon anaerobiosis and varied with external pH . The pH dependence disappeared under fully aerobic conditions . Mutations in earA had no effect upon hyd expression . The two other regulators identified were oxrF, which controls aniH, and oxrG, which, in concert with oxrA and oxrB, controls aniC and aniI . The oxrG locus was mapped to 88 min and appears to code for a positive regulator . Various oxr mutants were subjected to two-dimensional polyacrylamide electrophoretic analysis of anaerobiosis-inducible proteins . Several pathways of anaerobic control were observed by means of these techniques.

Infect Immun, 1988 Feb, 56(2), 419 - 23
Characterization of aromatic- and purine-dependent Salmonella typhimurium: attention, persistence, and ability to induce protective immunity in BALB/c mice; O'Callaghan D et al.; Stable transposon-generated auxotrophic mutations in aroA, purA, and purE or aroA and purA together were introduced into Salmonella typhimurium strains which were virulent in mice . Strains harboring any of these mutations were attenuated when tested in BALB/c mice . purE strains were less attenuated than aroA or purA strains . Both aroA and purA mutants persisted for several weeks in the livers and spleens of the mice after intravenous infection, although the numbers of viable cells detected at various times after infection differed . aroA strains persisted at a higher level than purA strains and were effective live vaccines given intravenously or orally . purA strains were ineffective as oral vaccines and were poor intravenous vaccines . Strains harboring both aroA and purA mutations together were ineffective vaccines when administered orally or intravenously even though they persisted in the livers and spleens of the mice for long periods after intravenous infection.

Jpn J Med Sci Biol, 1988 Feb, 41(1), 1 - 13
An outbreak of salmonellosis in newly imported cynomolgus monkeys; Takasaka M et al.; Serious salmonellosis occurred in groups of cynomolgus monkeys newly imported into Tsukuba Primate Center for Medical Science from the Philippines in 1985 . During the quarantine period, Salmonella typhimurium (29 strains) and S . stanley (1 strain) were isolated from 30 of 130 imported monkeys . Twenty-eight of the 30 infected monkeys excreted mainly watery diarrhea, and occasionally bloody mucous stool . Seven of the 28 clinical cases infected with S . typhimurium resulted in death or in moribund state . In both the small and large intestines of autopsied monkeys, acute inflammatory changes were observed.

Eur J Clin Microbiol Infect Dis, 1988 Feb, 7(1), 45 - 7
Salmonella bacteremia in African patients with human immunodeficiency virus infection; De Wit S et al.; During a two-year period, 26 Central African patients with AIDS or AIDS-related complex were seen in two Belgian hospitals and five of these patients presented with non-typhoid Salmonella bacteremia . Three additional patients were observed in a Rwandese hospital . These eight African patients were compared with 16 non-AIDS patients with non-typhoid Salmonella bacteremias . The patients with AIDS or AIDS-related complex did not have gastroenteritis, but they did have a high recurrence rate and high prevalence of Salmonella typhimurium . Long-term antibiotic prophylaxis seems warranted for such patients despite the high frequency of side effects from antibioticsPIP: Between January 1982 and December 1983, health practitioners at 2 Belgian hospitals examined 26 Africans with human immunodeficiency virus (HIV) infection . 5 of these patients also had non-typhoid Salmonella bacteremia . These 5 patients originated from Zaire . 3 additional patients with both acquired immunodeficiency syndrome (AIDS) or AIDS-related complex (ARC) and Salmonella bacteremia were seen at a hospital in Rwanda . Researchers compared these 8 African patients with 16 non-African, non-HIV patients with Salmonella bacteremias . 4 of these 16 patients experienced associated gastroenteritis, but none of the AIDS or ARC patients had gastroenteritis which is often the case with HIV infections . The AIDS or ARC patients did, however, have a high recurrence rate and high prevalence of Salmonella typhimurium . Therefore, a longterm antibiotic prophylaxis seems appropriate for such patients even though there is a high frequency of side effects from antibiotics . Further studies are warranted to evaluate efficacy and toleration of longterm prophylaxis, such as with the antibiotics called quinolines, in HIV infected patients .

Infect Immun, 1988 Feb, 56(2), 310 - 3
Genetic control of Salmonella typhimurium-induced depression of delayed-type hypersensitivity to sheep erythrocytes in mice; Nauciel C et al.; Infection of mice with a temperature-sensitive mutant of Salmonella typhimurium C5TS allowed the survival of genetically susceptible mice . The ability to mount a delayed-type hypersensitivity (DTH) response to sheep erythrocytes during infection with C5TS was studied in various inbred mouse strains, recombinant inbred strains derived from C57BL/6 (susceptible) and A/J (resistant) mice, and C3H congenic mice . Suppression of the DTH response to sheep erythrocytes was found in mice that carried the Itys allele, the H-2b haplotype, or both . These genes are known to increase susceptibility to S . typhimurium infection . In contrast, no DTH response suppression was observed in mouse strains that carried other genes that increased susceptibility to S . typhimurium, e.g., DBA/2 and C3H/HeJ . Apart from a transient suppression in A/J mice, the DTH responses of resistant mice (A/J and CBA) were normal or increased . The DTH response to sheep erythrocytes could be restored in immunodepressed mice by increasing the immunizing dose, suggesting the possible role of activated macrophages in depression of the DTH response.

Carcinogenesis, 1988 Feb, 9(2), 327 - 9
Inhibition of 2-aminofluorene mutagenesis in bacteria by inducers of cytochrome P-450d; Miller DM et al.; Certain chemical inducers of rat liver microsomal cytochrome P-450d are tightly bound to the cytochrome . We investigated the ability of two inducers of cytochrome P-450d, Aroclor 1254 and isosafrole, to inhibit the microsomal activation of 2-aminofluorene to a mutagen as measured in Salmonella typhimurium . Butanol treatment of microsomes from isosafrole-treated rats removed an inhibitory metabolite of isosafrole and increased 2-aminofluorene mutagenesis by approximately 2-fold over controls . Butanol treatment of microsomes from Aroclor 1254-treated rats failed to either remove any of the Aroclor 1254 associated with microsomal cytochrome P-450 or affect 2-aminofluorene-induced mutagenesis . However, addition of Aroclor 1254 to butanol-treated microsomes from isosafrole-treated rats almost completely inhibited 2-aminofluorene mutagenesis . Aroclor 1254 completely inhibited the cytochrome P-450d-dependent estradiol 2-hydroxylase activity of butanol-treated microsomes from isosafrole-treated rats . Thus, we suspect that certain congeners from Aroclor 1254, a widely used mixture for induction of cytochrome P-450 activities, could inhibit cytochrome P-450d and partially mask its ability to metabolize some chemicals to mutagens.

Biull Eksp Biol Med, 1988 Feb, 105(2), 158 - 60
{Ability of a lipopolysaccharide toxin to intensify the functional response of human thrombocytes to thrombin stimulation}; Viktorov AV et al.; The preincubation of isolated washed human platelets with lipopolysaccharide toxin (LPS) from Salmonella typhimurium (10 min, 37 degrees) speeds up the thrombin-induced aggregation . Besides, LPS-pretreatment was shown to alter the turnover of polyphosphoinositides stimulated by thrombin and significantly elevated concentrations of diacylglycerol and thromboxane B2 in comparison with control platelets . However, LPS does not influence on the lipid fluidizing effect of thrombin action as testifies by ESR spectroscopy with doxyl-stearic acids as spin-probes . An LPS pretreatment of platelets that induces no aggregation by itself is proposed might transform cells into a state of hidden activation" associated with the accumulation of such products as diacylglycerol and precursors of thromboxane B2 . Addition of thrombin to such "preactivated" platelets could cause a more effective aggregation.

J Bacteriol, 1988 Feb, 170(2), 883 - 8
Cloning and properties of the Salmonella typhimurium tricarboxylate transport operon in Escherichia coli; Widenhorn KA et al.; The tricarboxylate transport operon (tctI) was cloned in Escherichia coli as a 12-kilobase (kb) fragment from an EcoRI library of the Salmonella typhimurium chromosome in lambda gtWES . It was further subcloned as a 12-kb fragment into pACYC184 and as an 8-kb fragment into pBR322 . By insertional mutagenesis mediated by lambda Tn5, restriction mapping, and phenotypic testing, the tctI operon was localized to a 4.5-kb region . The tctC gene which encodes a periplasmic binding protein (C protein) was located near the center of the insert . E . coli/tctI clones on either multicopy or single-copy vectors grew on the same tricarboxylates as S . typhimurium, although unusually long growth lags were observed . E . coli/tctI clones exhibited similar {14C}fluorocitrate transport kinetics to those of S . typhimurium, whereas E . coli alone was virtually impermeable to {14C}fluorocitrate . The periplasmic C proteins (C1 and C2 isoelectric forms) were produced in prodigious quantities from the cloned strains . Motile E . coli/tctI clones were not chemotactic toward citrate, whereas tctI deletion mutants of S . typhimurium were . Taken together, these observations indicate that tctI is not an operon involved in chemotaxis.

J Bacteriol, 1988 Feb, 170(2), 588 - 97
Overproduction of the MotA protein of Escherichia coli and estimation of its wild-type level; Wilson ML et al.; The motA gene of Escherichia coli was placed under the control of a high-level promoter, that of the tryptophan operon of Serratia marcescens . In the presence of the inducer beta-indoleacrylic acid, MotA was synthesized at greatly elevated levels and inserted without apparent limit into the inner membrane . Growth and motility were impaired, but not drastically so, indicating that MotA by itself does not act as a proton ionophore . Antibody raised against the overproduced protein was used to estimate that a wild-type cell contained 600 +/- 250 copies of MotA . This number is more than would be needed to surround each flagellar basal body with a single circlet of MotA protein; possible interpretations of the result are discussed . The antibody was also used to establish that the MotA protein of Salmonella typhimurium has a similar molecular weight to that of E . coli and is immunologically cross-reactive with it; functional complementation of S . typhimurium motA mutants by the E . coli gene was established.

J Bacteriol, 1988 Feb, 170(2), 534 - 9
Rapid response to osmotic upshift by osmoregulated genes in Escherichia coli and Salmonella typhimurium; Jovanovich SB et al.; The rapid in vivo response of both Escherichia coli and Salmonella typhimurium osmoregulated genes to an osmotic upshift was analyzed in detail by using chromosomal operon fusions . Within 10 min after the addition of 0.3 M NaCl to the culture medium, the differential rates of expression of both an S . typhimurium proU-lac fusion and a proP-lac fusion increased by 180- and 17-fold respectively, while an E . coli ompC-lac fusion increased by 3.4-fold . For all three stimulated promoters, the increased rate of expression was maintained until about 40 min after the osmotic upshift . Thereafter, proU expression continued at a steady-state rate that was 27-fold higher than that of the control, while proP and ompC expression fell to 1.4- and 2-fold of the control rates, respectively . In contrast, expression of an E . coli ompF-lac fusion decreased twofold within 2.5 min . For proU, the length of the lag phase, which preceded the onset of the rapid response, increased with the degree of osmotic upshift, above a threshold of 0.2 M NaCl; the onset of the rapid proU response also preceded the resumption of growth . The rapid response phase, which was first quantitated for proU, proP, ompC, and ompF in this study, is an important component of the osmoregulation of these promoters . The addition of the osmoprotectant glycine betaine at the time of osmotic upshift decreased both the length of the rapid response and the subsequent steady-state of expression of proU.

J Bacteriol, 1988 Feb, 170(2), 736 - 43
Isolation and characterization of a selenium metabolism mutant of Salmonella typhimurium; Kramer GF et al.; Selenium is a constituent in Escherichia coli of the anaerobic enzyme formate dehydrogenase in the form of selenocysteine . Selenium is also present in the tRNA of E . coli in the modified base 5-methylaminomethyl-2-selenouracil (mnm5Se2U) . The pathways of bacterial selenium metabolism are largely uncharacterized, and it is unclear whether nonspecific reactions in the sulfur metabolic pathways may be involved . We demonstrated that sulfur metabolic pathway mutants retain a wild-type pattern of selenium incorporation, indicating that selenite (SeO32-) is metabolized entirely via selenium-specific pathways . To investigate the function of mnm5Se2U, we isolated a mutant which is unable to incorporate selenium into tRNA . This strain was obtained by isolating mutants lacking formate dehydrogenase activity and then screening for the inability to metabolize selenium . This phenotype is the result of a recessive mutation which appears to map in the general region of 21 min on the Salmonella typhimurium chromosome . A mutation in this gene, selA, thus has a pleiotropic effect of eliminating selenium incorporation into both protein and tRNA . The selA mutant appears to be blocked in a step of selenium metabolism after reduction, such as in the actual selenium insertion process . We showed that the absence of selenium incorporation into suppressor tRNA reduces the efficiency of suppression of nonsense codons in certain contexts and when wobble base pairing is required . Thus, one function of mnm5Se2U in tRNA may be in codon-anticodon interactions.

Biochemistry, 1988 Jan 26, 27(2), 824 - 32
Folding of homologous proteins: conservation of the folding mechanism of the alpha subunit of tryptophan synthase from Escherichia coli, Salmonella typhimurium, and five interspecies hybrids; Stackhouse TM et al.; The equilibrium and kinetic properties for the urea-induced unfolding of the alpha subunit of tryptophan synthase from Escherichia coli, Salmonella typhimurium, and five interspecies hybrids were compared to determine the role of protein folding in evolution . The parent proteins differ at 40 positions in the sequence of 268 amino acids, and the hybrids differ by up to 15 amino acids from the Escherichia coli alpha subunit . The results show that all the proteins follow the same folding mechanism and are consistent with a previously proposed hypothesis {Hollecker, M., & Creighton, T . E . (1983) J . Mol . Biol . 168, 409; Krebs, H., Schmid, F . X., & Jaenicke, R . (1983) J . Mol . Biol . 169, 619} that the folding mechanisms are conserved in homologous proteins . Analysis of the kinetic data suggests that the 15 positions at which the parent proteins differ in the amino folding unit, residues 1-188, do not play a role in a rate-limiting step in folding that has been previously identified as the association of the amino and carboxyl folding units {Beasty, A . M., Hurle, M . R., Manz, J . T., Stackhouse, T . S., Onuffer, J . J., & Matthews, C . R . (1986) Biochemistry 25, 2965} . One or more of the 25 positions at which the parent proteins differ in the carboxyl folding unit, residues 189-268, do appear to play a role in this same rate-limiting step.

J Biol Chem, 1988 Jan 15, 263(2), 958 - 64
Diaminopropionate ammonia-lyase from Salmonella typhimurium . Purification and characterization of the crystalline enzyme, and sequence determination of the pyridoxal 5'-phosphate binding peptide; Nagasawa T et al.; We have found a wide occurrence of alpha,beta-diaminopropionate ammonia-lyase in bacteria and actinomycetes . Considerable amounts of this enzyme were found in Salmonella typhimurium . The enzyme was purified and crystallized from S . typhimurium (IFO 12529) . The relative molecular mass of the native enzyme, estimated by the ultracentrifugal equilibrium method, is 89,000 Da, and the enzyme consists of two subunits identical in molecular mass . The enzyme exhibits absorption maxima at 278 and 413 nm and contains 2 mol of pyridoxal 5'-phosphate(pyridoxal-P)/mol of enzyme . The enzyme catalyzes the alpha,beta-elimination reaction of both L- and D-alpha,beta-diaminopropionate, the most suitable substrates, to form pyruvate and ammonia . The L- and D-isomers of serine were also degraded, though slowly . After the internal Schiff base with pyridoxal-P had been reduced with sodium borohydride, followed by trypsin or lysyl endopeptidase digestion of the enzyme, we determined the sequence of about 20 amino acid residues around the lysine residue which binds pyridoxal-P . No homology was found in either the amino acid sequence of the pyridoxal-P binding peptide or the amino-terminal amino acid sequence between the enzyme and other pyridoxal-P-dependent enzymes.

Proc Natl Sci Counc Repub China B, 1988 Jan, 12(1), 14 - 20
Mutagenicity of Maillard browning reaction products from various nitrosated amino acid-glucose mixtures; Yen GC et al.; Ten different amino acid-glucose Maillard browning products before and after reaction with nitrite were evaluated by the Ames mutagenicity assay . No mutagenic response was observed in the methylene chloride extracts of any browning products tested before nitrosation . However, mutagenicity was showed in most of the browning mixtures, e.g., glycine-glucose, lysine-glucose (I), arginine-glucose, phenylalanine-glucose (II), and methionine-glucose after nitrosation when examined by Salmonella typhimurium strains TA98 and TA100 either with or without S-9 metabolic activation . Among the browning mixtures, (I) and (II) showed the greatest mutagenic activity after reaction with nitrite . The mutagenicity of lysine-glucose with nitrite was dependent on browning intensity, nitrosation pH, nitrosation time, nitrite level and blocking agents.

J Toxicol Environ Health, 1988, 24(3), 345 - 56
Mutagenic potential of binary mixtures of nitro-polychlorinated dibenzo-p-dioxins and related compounds; Donnelly KC et al.; The mutagenic potential of binary mixtures of nitro-polychlorinated dibenzo-p-dioxins and other environmentally related compounds was determined using Salmonella typhimurium strain TA98 in the standard plate incorporation assay . Samples tested included binary mixtures of 4-nitro-4'-chlorobiphenyl with 6-nitro-4,2',3',4',5'-pentachlorobiphenyl, 4-nitrobenzo-p-dioxin with 4-nitro-2,3,8-trichlorodibenzo-p-dioxin, and benzo{a}pyrene with either nitropentachlorobiphenyl or nitrotrichlorodibenzo-p-dioxin . Inhibition was the primary interaction observed for the mixtures of polyhalogenated dioxins or biphenyls with the direct-acting mutagens nitrodibenzo-p-dioxin or nitrochlorobiphenyl . At the highest dose tested, nitrotrichlorodibenzo-p-dioxin inhibited the bacterial mutagenicity of nitrodibenzo-p-dioxin by almost 50%, while pentachlorobiphenyl inhibited the mutagenicity of nitrobiphenyl by 34% . Conversely, synergism was the primary interaction observed for mixtures of halogenated aromatics with the promutagen benzo{a}pyrene . The addition of nitrotrichlorodioxin to benzo{a}pyrene enhanced the mutagenicity of the latter compound by as much as 70%, while the mutagenic potential of a mixture of benzo{a}pyrene and nitropentachlorobiphenyl was approximately 50% greater than the mutagenicity of benzo{a}pyrene alone . In summary, mixtures of nonmutagenic nitropolyhalogenated biphenyls or dibenzo-p-dioxins appear to inhibit the mutagenicity of direct-acting mutagens, while these same compounds seem to enhance the mutagenic potential of the promutagen benzo{a}pyrene.

J Cancer Res Clin Oncol, 1988, 114(2), 215 - 6
Absence of in vitro mutagenicity of the fluid from breast cysts of women with macrocystic disease; Arzimanoglou II et al.; Cystic fluid from 30 Greek women suffering from macrocystic disease was tested for mutagenicity in the Salmonella typhimurium mutagenicity assay using three bacterial strains in the presence or absence of liver homogenate . None of the samples tested showed mutagenic potential in this test supporting the absence of potential carcinogens in the cyst fluids.

Pediatr Infect Dis J, 1988 Jan, 7(1), 44 - 8
Predictors for extraintestinal infection in Salmonella enteritis in Thailand; Sirinavin S et al.; To identify the risks and predictors for extraintestinal Salmonella infection (ETI) in infants and children with nontyphoidal Salmonella enteritis, we performed a retrospective review of 326 infants and children with diarrhea and rectal swab cultures positive for nontyphoidal Salmonella enteritis seen at Ramathibodi Hospital between 1981 and 1983 . Nineteen patients had bacteremia . The overall rate of bacteremia was 5.8% which was 24.3% of those having blood cultures taken . Salmonella typhimurium was the most common cause of ETI and the most invasive among the common serotypes causing enteritis . The clinical characteristics of the patients with high probabilities of having ETI were: younger than 6 months of age; high body temperature; and immunocompromising conditions . The observed frequency of ETI in these patients was 21.9 to 26.3% compared with 0 to 0.7% in patients without those risk factors.

Carcinogenesis, 1988 Jan, 9(1), 37 - 43
Various short-term assays and two long-term studies with the plasticizer di(2-ethylhexyl)phthalate in the Syrian golden hamster; Schmezer P et al.; The plasticizer di(2-ethylhexyl)phthalate (DEHP) and its main metabolite monethylhexylphthalate (MEHP) were investigated in several short-term in vitro assays, including mutagenicity in Salmonella typhimurium TA102, a strain sensitive to mutations arising as a cause of oxidative DNA damage . Also DNA amplification in SV40-transformed Chinese hamster cells and DNA damage in rat and hamster hepatocytes were investigated . The two compounds were not genotoxic in any of the test systems . Furthermore, DEHP was investigated in two long-term bioassays with Syrian golden hamsters using both i.p . (max . total dose 54 g/kg) and inhalative (7-10 mg/kg) application . In both experiments an additional group of animals received a combination treatment of DEHP with N-nitrosodimethylamine (NDMA) . These studies were included in order to elucidate whether the observed influence of DEHP on the microsomal enzyme activity (Seth, 1982) may effect the carcinogenic activity of NDMA . There was no significant increase in tumor incidence after application of only DEHP via both routes . However, the occurrence of liver malignancies was significantly (P less than 0.001) reduced after the combination treatment in the inhalation study.

Zentralbl Bakteriol Mikrobiol Hyg {A}, 1988 Jan, 267(3), 395 - 403
{Effect of Propionibacterium granulosum KP-45 on the resistance to Listeria monocytogenes and Salmonella typhimurium infections}; Hof H et al.; Killed bacterial cells of Propionibacterium granulosum KP-45 were found to be potent modifiers of non-specific resistance of mice against infection with either Listeria monocytogenes or Salmonella typhimurium . Injection of P . granulosum 7 days prior to infection resulted in marked splenomegaly . Disseminated acute inflammatory foci were found histologically in the liver . These mice were apparently less susceptible to infection, since definitely lower bacterial counts were determined . Simultaneous application of both P . granulosum KP-45 and L . monocytogenes resulted, however, in increased susceptibility of mice to infection, since definitely higher bacterial counts were found and the inflammatory reaction to infection was markedly enhanced.

Environ Mol Mutagen, 1988, 11(3), 315 - 22
Flavone mutagenicity in Salmonella typhimurium: dependence on the pKM101 plasmid and excision-repair deficiency; MacGregor JT et al.; Flavones mutagenic in Salmonella typhimurium fall into two distinct classes, characterized by different structural and metabolic activation requirements and by different strain responses . The mutagenic potencies of a prototype agent of each class, quercetin (3,3',4',5,7-hydroxyflavone) and norwogonin (5,7,8-hydroxyflavone), were determined in tester strains differing in excision-repair capability and in the presence or absence of plasmid pKM101 . Two series of strains were used, one with the hisD3052 frameshift mutation and one with the hisG46 missense mutation . With both agents and for both series of strains, the mutagenic response was markedly dependent on the absence of excision repair and the presence of the pKM101 plasmid.

Environ Mol Mutagen, 1988, 11(2), 225 - 34
Mutagenic potency of chlorofuranones and related compounds in Salmonella; Ishiguro Y et al.; One of the mutagenic byproducts associated with chlorinated humic waters and kraft pulp bleaching effluents was recently identified as 3-chloro-4-(dichloromethyl)-5-hydroxy-2(5H)-furanone . This compound and several related chlorofuranones and precursors were synthesized and evaluated for direct-acting mutagenicity in Salmonella typhimurium tester strain TA100 . Mutagenicity was greatest for 3-chloro-4-(dichloromethyl)-5-hydroxy-2(5H)-furanone, its 5-methoxy derivative, and the precursor in their synthesis, 3-(dichloromethyl)-2,4,4-trichloro-2-butenoic acid . Several of the compounds were tested in the presence of added rat liver homogenate S9 fraction, and in all cases mutagenicity was substantially reduced . An important structural feature which may govern the mutagenic response in these instances appears to be the cis arrangement of CHCl2 and Cl substituents on a carbon-carbon double bond . These compounds may also be transformed in vitro to the same acyclic chlorine substituted alpha, beta-unsaturated aldehyde derivative, which is proposed to be the agent responsible for the observed mutagenicity.

Environ Mol Mutagen, 1988, 11(2), 195 - 206
Comparative mutagenicity of nine brands of coffee to Salmonella typhimurium TA100, TA102, and TA104; Shane BS et al.; Nine coffee preparations, four caffeinated instant brands, three caffeinated drip coffees, and two decaffeinated coffees, one of which was an instant brand, were evaluated for mutagenicity by the Ames assay using Salmonella typhimurium TA100, TA102, and TA104 . All the coffees contained direct-acting mutagens, which reverted the three strains . The inclusion of a rat microsomal enzyme preparation reduced the mutagenic response of the three strains in the presence of some of the coffee samples . Both glyoxal and methylglyoxal, 1,2-dicarbonyls found in the coffees were mutagenic . The concentration of glyoxal, methyglyoxal, diacetyl, and guiacol were measured by gas chromatography/mass spectrometry . Caffeine, furfural, and 5-methylfurfural concentrations were determined by high performance liquid chromatography . Although lower concentrations of methyglyoxal were found in the drip caffeinated coffees, the mutagenic potency of these preparations was higher than the instant coffees on a weight basis especially when TA104 was the indicator organism . Our findings agree with those of other workers who have shown that carbonyl compounds, which were present in all the brands tested, are partially responsible for the mutagenic response of coffee but that additional mutagens are also present.

Chem Biol Interact, 1988, 65(1), 59 - 71
Bacterial cysteine conjugate beta-lyase and the metabolism of cysteine S-conjugates: structural requirements for the cleavage of S-conjugates and the formation of reactive intermediates; Vamvakas S et al.; The cysteine conjugate beta-lyase mediated metabolism and the mutagenicity of the synthetic cysteine conjugates S-(2-chloroethyl)-L-cysteine (CEC), S-(2-chlorovinyl)-L-cysteine (CVC), S-(1,2,3,3,3-pentachloroprop-1-enyl)-L-cysteine (PCPC), S-(pentachlorophenyl)-L-cysteine (PCPhC), S-(chloro-1,2,2-trifluoroethyl)-L-cysteine (CTFEC), S-benzyl-L-cysteine (SBC) and S-methyl-L-cysteine (SMC) were investigated in Salmonella typhimurium strains TA100, TA2638, TA102 and TA98 to establish structure/activity relationships . Bacterial 100,000 X g supernatants cleaved CTFEC, PCPC, CVC, PCPhC and SBC to pyruvate; pyruvate formation was inhibited by the beta-lyase inhibitor aminooxyacetic acid (AOAA) in all cases . Of the compounds tested, CEC, PCPC and CVC were mutagenic in the Ames-test . CTFEC, PCPhC and SBC failed to increase the number of revertants above control levels . The mutagenicity of PCPC and CVC could be inhibited by AOAA . CEC exerted a potent mutagenic effect in the Ames-test which was not affected by AOAA; CEC was not transformed to pyruvate by bacterial beta-lyase . Neither pyruvate formation nor mutagenicity were observed with SMC . These results indicate that the structure of the substituent on the sulfur atom is an important determinant for the biological activity of cysteine S-conjugates . Electronegative and/or unsaturated substituents are required for beta-lyase catalysed beta-elimination reactions . The formation of chemically unstable thiols, which may be converted to thioacylating intermediates, seems to be a prerequisite for beta-lyase dependent mutagenicity of S-conjugates.

Environ Mol Mutagen, 1988, 11 Suppl 12, 1 - 157
Salmonella mutagenicity tests: IV . Results from the testing of 300 chemicals; Zeiger E et al.; Three hundred chemicals were tested for mutagenicity, under code, in Salmonella typhimurium, using a preincubation protocol . All tests were performed 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 . The results and data from these tests are presented.

Toxicol Lett, 1988 Jan, 40(1), 21 - 8
Mutagenicity of monochlorodibenzofurans detected in the environment; Matsumoto M et al.; Recently, monochlorodibenzofuran, which is formed by the reaction of dibenzofuran with residual chlorine, has been detected in tap water in one region of Japan . The mutagenicities of 1-, 2-, 3-, and 4-chlorodibenzofuran were tested using Salmonella typhimurium TA98 and TA100 . 1-Chlorodibenzofuran and 4-chlorodibenzofuran proved to be practically non-mutagenic, while 2-chlorodibenzofuran was weakly mutagenic . Unlike these three isomers, 3-chlorodibenzofuran was markedly mutagenic, and the intensity of its mutagenicity in TA98 was about one-fifth and in TA100 about one-twentieth of that of benzo{a}pyrene.

J Trauma, 1988 Jan, 28(1 Suppl), S217 - 9
The effect of trauma to the leg on the first-pass uptake of bacteria by the lung; Behm KE et al.; Our previous studies have shown that the first-pass pulmonary uptake of lidocaine and serotonin were not impaired by bullet wounding of the leg . Since there is decreased resistance to bacterial infection with trauma, it was of interest to study the uptake of bacteria . First-pass pulmonary uptake of 51-chromium-labeled, killed Salmonella typhimurium bacteria was studied in 26 pigs . In 16 controls, four injections at hourly intervals revealed an initial uptake of 84.5% +/- 1.5 (Mean +/- S.E.M.) and a 95% first-pass uptake of 78.6% +/- 2.4, and no significant change with time . In the ten traumatized animals only the values at 5 hours were significantly lower than the controls . It is concluded that repeated injections of killed Salmonella typhimurium bacteria without trauma do not interfere with the ability of the lung to remove these bacteria during their first passage through the lung, but that with trauma to the leg do to a slight degree.

Environ Mol Mutagen, 1988, 11(1), 79 - 90
Photochemical formation of mutagenic compounds from alkenes and ozone or nitrogen dioxide; Victorin K et al.; In order to investigate the possible formation of mutagenic compounds from alkenes emitted in ambient air, laboratory experiments were performed with Salmonella typhimurium strain TA100 in a small-scale flow-through exposure system . The reaction time for mixtures of alkenes with ozone or nitrogen dioxide was 40 minutes, and the exposure time for bacteria was 6 hours . Ozone gave rise to a small mutagenic effect in combination with 1,3-butadiene or vinyl chloride, with and without ultraviolet (UV) irradiation, but not in combination with ethene or propene . Nitrogen dioxide gave rise to a mutagenic effect in combination with propene, 1,3-butadiene, or vinyl chloride, but only after UV irradiation . The mutagenic activity was highest with butadiene and seemed to be dose-related to the concentration of nitrogen dioxide . Nitrogen dioxide with ethene did not produce a mutagenic effect . A mixture of ethene, propene, and butadiene, tested with ozone or nitrogen dioxide with UV irradiation, did not potentiate each other's mutagenic effect.

Environ Mol Mutagen, 1988, 11(1), 65 - 77
A method for studying the mutagenicity of some gaseous compounds in Salmonella typhimurium; Victorin K et al.; A dynamic flow-through exposure system was designed for mutagenicity studies of gaseous compounds in Salmonella . Salmonella typhimurium strain TA100 was the primary tester strain . The dose ranges were 0.5-20% of vinyl chloride, ethene, propene, and 1,3-butadiene, 1-200 ppm of ethylene oxide, 0.5-20 ppm of nitrogen dioxide, and 0.1-3.5 ppm of ozone . The gas flow rate was 250, 500, or 1,000 ml/min, and the exposure time was 6 or 7 hours . Of the tested gases, vinyl chloride, ethylene oxide, and nitrogen dioxide were mutagenic . Ethene, propene, and 1,3-butadiene were not mutagenic in this system . Ozone is bacteriotoxic, and no mutagenic effect could be demonstrated in the nontoxic dose range . The exposure system was considered suitable for studies on gaseous chemicals.

Mutat Res, 1988 Jan, 197(1), 39 - 49
Modulation of the mutagenic effects of 2-amino-3-methylimidazo{4,5-f}quinoline (IQ) and 2-amino-3,4-dimethylimidazo{4,5-f}quinoline (MeIQ) in bacteria with rat-liver 9000 x g supernatant or monolayers of rat hepatocytes as an activation system; Holme JA et al.; An in vitro protocol was designed to separate the process of metabolic activation from the mutational events . Cultured rat hepatocytes were first incubated with the food mutagens 2-amino-3-methylimidazo{4,5-f}quinoline (IQ) or 2-amino-3,4-dimethylimidazo{4,5-f}quinoline (MeIQ) . After the incubation period the medium was removed and further incubated with Salmonella typhimurium TA98 . A high direct mutagenic activity of the culture medium was then measured . The half-lives of the mutagenic metabolites formed from IQ and MeIQ were in the order of 45 min . The presence of the cytochrome P450 inhibitors alpha-naphthoflavone and metyrapone during the pre-incubation period reduced the accumulation of mutagenic metabolites . No effects of ascorbate on the mutagenic effects of IQ and MeIQ were seen . (+)-Catechin, another antioxidant and free-radical scavenger, markedly enhanced the number of IQ/MeIQ-induced revertants when added to the hepatocytes . In contrast, (+)-catechin clearly decreased the number of revertants when 9000 X g supernatant from rat liver (S9) was used as an activation system . No marked effect of pentachlorophenol, an inhibitor of hepatocyte sulfation and bacterial O-acetylation, was seen using hepatocytes as an activation system, while the mutagenic activity of both IQ and MeIQ was reduced by 90% in the S9/Salmonella system . The addition of an inhibitor of glucuronidation, galactosamine, or the nucleophile glutathione caused no or only minor decreases in the genotoxic effects of the IQ compounds . With both S9 and hepatocytes as activation systems the relative mutagenic effects observed in the S . typhimurium strains TA98 and TA98 NR were in the same order of magnitude, while a large decrease was seen with TA98/1,8-DNP6 . The results show that this in vitro test protocol may be useful as a tool to study mechanisms involved in the formation of mutagenic metabolites.

J Med Microbiol, 1988 Jan, 25(1), 41 - 7
Electronmicroscopic studies on the location of salmonella proliferation in the murine spleen; Wang XM et al.; Highly susceptible inbred male C57BL/6 mice were infected intraperitoneally with 2 x 10(7) cfu of a virulent Salmonella typhimurium strain . Tissue sections were taken from the spleen 2 and 3 days after infection for examination by electronmicroscopy . Rapid infiltration of polymorphs and macrophages was evident at the site of infection . These inflammatory phagocytes displayed avid destructive action against ingested bacteria . Bacterial multiplication occurred primarily in extracellular locations within sinusoids or in lesions containing disintegrating host cells.

J Leukoc Biol, 1988 Jan, 43(1), 11 - 7
Glycolipid induced proliferation of lipopolysaccharide hyporesponsive C3H/HeJ splenocytes; Tomai MA et al.; Although the C3H/HeJ mouse is hyporesponsive to lipopolysaccharides (LPS), certain forms of the lipid A fraction have been shown to stimulate cells from this mouse strain . To determine the role of the oligosaccharide chain length on the lipid A-induced proliferation of C3H/HeJ splenocytes, a panel of glycolipids from R-chemotypes (Re, Rc, and Rd) and a nontoxic monophosphoryl lipid A (MPL) were tested . The MPL cells isolated from the MPL of Salmonella minnesota, Salmonella typhimurium, and the Reglycolipids isolated from Escherichia coli were found to be effective at stimulating the LPS-hyporesponsive spleen cells . A Re-glycolipid isolated from a different strain of E . coli cells was inactive, as were the S . minnesota Rc and Rd chemotypes . Proliferation induced by MPL and the active Re preparations was dose dependent and was inhibited by polymyxin B . Thus, if contamination of the Re-LPS or MPL with lipid A-associated protein occurred, it was below functional levels . The data suggest that the C3H/HeJ spleen cells are capable of responding to certain glycolipids, but they may lack the ability to convert native LPS into a stimulatory signal . In addition, a monosaccharide precursor of lipid A (lipid X), and a monoacyl glucosamine phospholipid derivative of lipid X (MaGP), were capable of inhibiting the proliferation induced by the MPL and Re-glycolipids . These data are compatible with the existence of a spleen cell receptor for lipid A.

J Infect Dis, 1988 Jan, 157(1), 78 - 84
Oral immunization with live, avirulent fla+ strains of Salmonella protects mice against subsequent oral challenge with Salmonella typhimurium; Hackett J et al.; Some strains of Salmonella, when fed to mice, establish a nonlethal, limited infection in the Peyer's patches of the small intestine . When such mice are later challenged orally with a normally lethal dose of virulent Salmonella typhimurium, a protective effect of the prior vaccination is seen . In an effort to characterize the determinant(s) of the avirulent strains responsible for this protective effect, we examined the cell envelope protein profiles of five such protective strains and of eight strains of Salmonella that were both nonpersistent and nonprotective when fed to mice . The protective strains produced high levels of flagellin . We made otherwise isogenic fla+ and fla- derivatives of two such strains and showed that although the fla- derivatives colonized mice as well as did the fla+ strains, the fla- derivatives given orally showed a much reduced ability to protect mice from S . typhimurium challenge . Both fla+ and fla- strains induced cellular immunity in vaccinated mice.

J Bacteriol, 1988 Jan, 170(1), 422 - 30
Rate and topography of cell wall synthesis during the division cycle of Salmonella typhimurium; Cooper S; The rates of synthesis of peptidoglycan and protein during the division cycle of Salmonella typhimurium have been measured by using the membrane elution technique and differentially labeled diaminopimelic acid and leucine . The cells were labeled during unperturbed exponential growth and then bound to a nitrocellulose membrane by filtration . Newborn cells were eluted from the membrane with fresh medium . The radioactivity in the newborn cells in successive fractions was determined . As the cells are eluted from the membrane as a function of their cell cycle age at the time of labeling, the rate of incorporation of the different radioactive compounds as a function of cell cycle age can be determined . During the first part of the division cycle, the ratio of the rates of protein and peptidoglycan synthesis was constant . During the latter part of the division cycle, there was an increase in the rate of peptidoglycan synthesis relative to the rate of protein synthesis . These results support a simple, bipartite model of cell surface increase in rod-shaped cells . Before the start of constriction, the cell surface increased only by cylindrical extension . After cell constriction started, the cell surface increased by both cylinder and pole growth . The increase in surface area was partitioned between the cylinder and the pole so that the volume of the cell increased exponentially . No variation in cell density occurred because the increase in surface allowed a continuous exponential increase in cell volume that accommodated the exponential increase in cell mass . Protein was synthesized exponentially during the division cycle . The rate of cell surface increase was described by a complex equation which is neither linear nor exponential.

J Bacteriol, 1988 Jan, 170(1), 42 - 7
Isolation of Salmonella typhimurium cys genes by transduction with a library of recombinant plasmids packaged in bacteriophage P22HT capsids; Monroe RS et al.; We have prepared a library of Salmonella typhimurium genomic fragments cloned in pBR322 and packaged in P22HT capsids . Plasmids carrying 24 of 26 specific genes searched for were isolated by transduction at frequencies of 1 to 344 per 10(6) plasmid transductants . All 11 known genes of the cysteine regulon were isolated from this library, including cysK, which we had previously been unable to clone in a recombinant plasmid with an Escherichia coli host . This library provides a simple and rapid method for isolating most S . typhimurium genes by using S . typhimurium itself as a host and should be particularly useful for cloning genes that might be deleterious to E . coli.

J Bacteriol, 1988 Jan, 170(1), 372 - 9
Comparative nucleotide sequence analysis of growth-rate-regulated gnd alleles from natural isolates of Escherichia coli and from Salmonella typhimurium LT-2; Barcak GJ et al.; A comparative study of gnd genes from Escherichia coli strains isolated from natural populations and laboratory strains and from Salmonella typhimurium was undertaken . In the accompanying paper (G . J . Barcak and R . E . Wolf, Jr., J . Bacteriol . 170:365-371, 1988), we showed that the growth-rate-dependent regulation of gnd expression was conserved among four natural E . coli isolates and E . coli B/r in a manner qualitatively similar to that of the gene from E . coli K-12 . Here, we report the DNA sequence of the 5' regulatory region and the first 125 codons of the structural gene for the five E . coli gnd genes and the gnd gene from S . typhimurium LT-2 . The sequences differed from one another by 5% on the average . All sequences defined putative secondary structures of the mRNA leader, which were previously proposed to be important in the regulation of the K-12 gene . In addition, a sequence between codons 69 and 74, which is highly complementary to the ribosome-binding site of the mRNA, was conserved in all the genes . The sequence data are discussed with respect to potential regulatory consequences.

J Bacteriol, 1988 Jan, 170(1), 345 - 51
Identification and characterization of starvation-regulated genetic loci in Salmonella typhimurium by using Mu d-directed lacZ operon fusions; Spector MP et al.; We used the technique of Mu d-directed lac operon fusion formation in an effort to identify loci in Salmonella typhimurium which are transcriptionally regulated by nutrient starvation conditions . We identified lacZ operon fusions in eight genetic loci, all of which exhibited increased transcription when starved for two or more of the following nutrients: nicotinate, phosphate, ammonium, glucose, and sulfate . The loci have been designated stiA to stiH for starvation-inducible loci . Mutations in two sti loci (stiC and stiD) significantly decreased cell viability during prolonged periods of nicotinate starvation, stiA and stiD are linked and map at 30 min . The stiC, stiE, stiG, and stiH loci mapped at approximately 77, 43, 88, and 56 min, respectively, on the S . typhimurium linkage map.

J Bacteriol, 1988 Jan, 170(1), 213 - 7
Formate-nitrate respiration in Salmonella typhimurium: studies of two rha-linked fdn genes; Paveglio MT et al.; Localized mutagenesis was used to obtain rha-linked mutations in Salmonella typhimurium, resulting in defects in the nitrate reductase-linked formate dehydrogenase (FDHN) . The fdn mutants obtained fell into two groups which differed in several respects . Group I isolates lacked FDHN activity under all conditions examined and exhibited wild-type levels of the hydrogenase-linked formate dehydrogenase (FDHH) . Group II isolates appeared defective in FDHN only when freshly prepared extracts were assayed; restoration of both FDHN and formate-nitrate reduction activity occurred on incubation of extracts for 2 to 3 h . Protease inhibitors prevented restoration . Group II isolates were also characterized by a conditional FDHH activity; this activity was absent unless the growth medium designed to optimize wild-type FDHH was altered either by lowering glucose concentration or by adding thiosulfate . Cotransduction of fdn with rha ranged from 4 to 22% for the group I isolates and from 20 to 40% for the group II isolates . Temperature-sensitive isolates from both groups synthesized FDHN activity with altered thermostability . In vitro complementation occurred in mixed extracts of amber mutants of the two respective classes . The results are consistent with two distinct rha-linked fdn genes, for which we suggest using the designations fdnB (group I) and fdnC (group II).

J Bacteriol, 1988 Jan, 170(1), 197 - 202
Nucleotide sequence of the Salmonella typhimurium mutS gene required for mismatch repair: homology of MutS and HexA of Streptococcus pneumoniae; Haber LT et al.; The mutS gene product of Escherichia coli and Salmonella typhimurium is one of at least four proteins required for methyl-directed mismatch repair in these organisms . A functionally similar repair system in Streptococcus pneumoniae requires the hex genes . We have sequenced the S . typhimurium mutS gene, showing that it encodes a 96-kilodalton protein . Amino-terminal amino acid sequencing of purified S . typhimurium MutS protein confirmed the initial portion of the deduced amino acid sequence . The S . typhimurium MutS protein is homologous to the S . pneumoniae HexA protein, suggesting that they arose from a common ancestor before the gram-negative and gram-positive bacteria diverged . Overall, approximately 36% of the amino acids of the two proteins are identical when the sequences are optimally aligned, including regions of stronger homology which are of particular interest . One such region is close to the amino terminus . Another, located closer to the carboxy terminus, includes homology to a consensus sequence thought to be diagnostic of nucleotide-binding sites . A third one, adjacent to the second, is homologous to the consensus sequence for the helix-turn-helix motif found in many DNA-binding proteins . We found that the S . typhimurium MutS protein can substitute for the E . coli MutS protein in vitro as it can in vivo, but we have not yet been able to demonstrate a similar in vitro complementation by the S . pneumoniae HexA protein.

J Bacteriol, 1988 Jan, 170(1), 117 - 25
Identification of a repressor gene involved in the regulation of NAD de novo biosynthesis in Salmonella typhimurium; Zhu N et al.; Mutations at the nadI locus affect expression of the first two genes of NAD synthesis, nadA and nadB, which are unlinked . Genetic data imply that the regulatory effects of nadI mutations are not due to indirect consequences of physiological alterations . Two types of mutations map in the nadI region . Common null mutations (nadI) show constitutive high-level expression of the nadB and nadA genes . Rare nadIs mutations cause constitutive low-level expression of nadB and nadA . Some nadIs mutations shut off the expression of the biosynthetic genes sufficiently to cause a nicotinic acid auxotrophy . Spontaneous revertants of auxotrophic nadIs mutants have a NadI- phenotype, including some with deletions of the nadI locus . The nadI locus encodes a repressor protein acting on the unlinked nadA and nadB genes.

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