Salmonella typhimurium

J Bacteriol, 1991 Jan, 173(2), 710 - 9
Nucleotide sequence and characterization of a Bacillus subtilis gene encoding a flagellar switch protein; Zuberi AR et al.; The nucleotide sequence of the Bacillus subtilis fliM gene has been determined . This gene encodes a 38-kDa protein that is homologous to the FliM flagellar switch proteins of Escherichia coli and Salmonella typhimurium . Expression of this gene in Che+ cells of E . coli and B . subtilis interferes with normal chemotaxis . The nature of the chemotaxis defect is dependent upon the host used . In B . subtilis, overproduction of FliM generates mostly nonmotile cells . Those cells that are motile switch less frequently . Expression of B . subtilis FliM in E . coli also generates nonmotile cells . However, those cells that are motile have a tumble bias . The B . subtilis fliM gene cannot complement an E . coli fliM mutant . A frameshift mutation was constructed in the fliM gene, and the mutation was transferred onto the B . subtilis chromosome . The mutant has a Fla- phenotype . This phenotype is consistent with the hypothesis that the FliM protein encodes a component of the flagellar switch in B . subtilis . Additional characterization of the fliM mutant suggests that the hag and mot loci are not expressed . These loci are regulated by the SigD form of RNA polymerase . We also did not observe any methyl-accepting chemotaxis proteins in an in vivo methylation experiment . The expression of these proteins is also dependent upon SigD . It is possible that a functional basal body-hook complex may be required for the expression of SigD-regulated chemotaxis and motility genes.

Infect Immun, 1991 Jan, 59(1), 398 - 406
Prostaglandin E release from human monocytes treated with lipopolysaccharides isolated from Bacteroides intermedius and Salmonella typhimurium: potentiation by gamma interferon; Nichols FC et al.; The purpose of this investigation was to examine gamma interferon potentiation of lipopolysaccharide (LPS) responses in human monocytes by using phenol-water-extracted (unfractionated) and highly purified LPS preparations isolated from Bacteroides intermedius and Salmonella typhimurium . Phenol-water-extracted LPS preparations from these bacteria were further purified by chromatography over Sepharose-CL-4B . LPS enrichment in pooled column fractions was assessed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and quantitation of hydroxy-fatty acid and 2-keto-3-deoxyoctulosonic acid content, protein contamination, and anthrone-reactive material . Monocyte stimulation by LPS, measured as prostaglandin E (PGE) release, was assessed with and without gamma interferon treatment . Cells were either treated simultaneously with gamma interferon and LPS or pretreated with gamma interferon prior to LPS stimulation . PGE release from counterflow-isolated monocytes was quantitated during the 0- to 24-h and 24- to 48-h culture intervals . Contrary to previous results from this laboratory, phenol-water-extracted LPS preparations from B . intermedius and S . typhimurium were similar in their capacities to stimulate PGE release from monocytes . Molecular sieve chromatography was found to remove substantial amounts of high-molecular-weight polysaccharide contaminants only from the B . intermedius LPS but did not significantly alter the potency of either B . intermedius or S . typhimurium LPS . Gamma interferon cotreatment did not potentiate the release of PGE with any of the LPS preparations tested . However, 24-h pretreatment of monocytes with gamma interferon followed by a 24-h exposure to LPS resulted in significant potentiation of PGE release over LPS alone . In addition, B . intermedium preparations were approximately threefold more potent than similarly prepared LPS isolates from S . typhimurium following gamma interferon pretreatment . These results indicate that gamma interferon can selectively potentiate the effects of B . intermedius LPS in human monocyte isolates.

Mikrobiyol Bul, 1991 Jan, 25(1), 94 - 107
{The mutagenic effects of sodium nitrite and monosodium glutamate used as food additives demonstrated by the Salmonella microsome test system}; Akin A et al.; In this study, the mutagenicity of sodium nitrite (an antimicrobial agent) and monosodium glutamate (a flavoring agent), which are widely used as food additives, have been evaluated . They were tested for mutagenicity in the Salmonella/microsome test system by employing plate-incorporation test in the absence and presence of rat-liver fraction, S 9 . No mutagenic activity was seen for monosodium glutamate in the Salmonella/microsome test system by using the tester strains Salmonella typhimurium TA98, TA100, TA1535 and TA1538 . Sodium nitrite was found mutagenic on S . typhimurium TA1535, whereas it was found weakly mutagenic on S . typhimurium TA100, in the presence and absence of rat-liver fraction, S 9.

Infection, 1991, 19 Suppl 4, S224 - 8
Liposomes and nanoparticles as vehicles for antibiotics; Kreuter J; Colloidal drug carriers such as liposomes and nanoparticles are easily taken up by phagocytic cells and accumulate in the organs of the reticuloendothelial system . Therefore, they hold promise as carriers for the treatment of intracellular infections with antibiotics that would normally not find easy access to intracellular sites . Consequently, in in vitro and in vivo experiments the therapeutic efficacy of substances such as amphotericin B, dihydrostreptomycin, amikacin, ampicillin, stibogluconate against a number of microorganisms including Leishmania donovani, Candida albicans, Staphylococcus aureus, Mycobacterium avium, Listeria monocytogenes, and Salmonella typhimurium was increased significantly by binding to liposomes and nanoparticles.

Microbiol Immunol, 1991, 35(3), 187 - 98
The 106-kilobase plasmid of Salmonella braenderup and the 100-kilobase plasmid of Salmonella typhimurium are not necessary for the pathogenicity in experimental models; Horiuchi S et al.; Among 1.041 clinical isolates (77 serovars) of Salmonella which had been derived from cases with acute enterocolitis, 601 (58%) contained one or more plasmids . Large serovar-specific plasmids were seen in 95 of 307 isolates (31%) of Salmonella typhimurium, in 34 of 34 isolates (100%) of Salmonella enteritidis and in 36 of 38 isolates (94.7%) of Salmonella braenderup: the sizes of which were 100, 60 and 106 kilobases (kb), respectively . In order to determine the role of these plasmids in pathogenicity for enterocolitis, the plasmids were eliminated from some strains of S . braenderup and S . typhimurium and the pathogenicity of the plasmid-less strains was compared with that of the parent strains by invasiveness to HeLa cells, fluid accumulation in the rabbit ligated ileal loop, lesion of mucosal tissue and the Sereny test . The virulence of all the plasmid-less strains was as strong as that of the plasmid-bearing strains in these pathogenicity assay systems . We therefore concluded that the 106-kb plasmid of S . braenderup and the 100-kb plasmid of S . typhimurium are not necessary for their pathogenicity in the experimental models: invasiveness to HeLa cells, fluid accumulation in the rabbit ligated ileal loop, and Sereny test.

Environ Mol Mutagen, 1991, 18(1), 41 - 50
Genotoxicity of nitrated polycyclic aromatic hydrocarbons and related structures on Escherichia coli PQ37 (SOS chromotest); Mersch-Sundermann V et al.; To determine the genotoxicity of nitrated polycyclic aromatic hydrocarbons and related molecules (nPAH) we examined 24 compounds representative of nitroanthracenes, nitrofluorenes, nitronaphthalenes, nitropyrenes, and nitroquinolines for genotoxicity in Escherichia coli PQ37 (SOS-chromotest) . To enhance the sensitivity of the tester strain and optimize metabolic activation we used a modified test protocol and S9-mix composition . All chemicals with the exception of 9-nitroanthracene, 1- and 2-nitronaphthalene, 2-methyl-1-nitronaphthalene, and 5-, 6-, and 8-nitroquinoline induced the SOS system of E . coli PQ37 . As expected from previously referred mutagenicity studies, the highest SOS inducing potencies (SOSIP) were exhibited by the dinitropyrenes (SOSIP = 151-416), 4-nitroquinoline-N-oxide (SOSIP = 62), and 3-nitrofluoranthese (SOSIP = 16) . Except for some nitronaphthalenes, the nPAHs showed their highest genotoxicity in the absence of an exogeneous metabolic activation system . The results were compared to those reported for the bacterial mutagenicity of these substances in Salmonella typhimurium TA98.

Environ Mol Mutagen, 1991, 18(1), 35 - 40
Inhibitory effect of lichen constituents on mutagenicity induced by heterocyclic amines; Osawa T et al.; Physodic acid, one of the main constituents of Hypogymnia enteromorpha, inhibited the mutagenicity of indirect mutagens, including benzo{a}pyrene and heterocyclic amines in Salmonella typhimurium TA 98 . In contrast, it was not effective against direct mutagens such as 6-nitropiperonal and adriamycin . Its antimutagenicity was not associated with free-radical scavenging or antioxidative activities . Physodic acid seemed to inhibit the formation of reactive metabolites, such as N-hydroxy-Trp-P-2, by blocking the hepatic microsomal oxidation systems . Another component of H . enteromorpha, physodalic acid, also inhibited mutagenicity of a heterocyclic amine, Trp-P-2, in S . typhimurium TA 98, even though it was reportedly mutagenic in S . typhimurium TA 100.

Microb Pathog, 1991 Jan, 10(1), 47 - 59
Expression cloning of Yersinia enterocolitica O:3 rfb gene cluster in Escherichia coli K12; al-Hendy A et al.; The genes of Yersinia enterocolitica serotype O:3 (YeO3) that determine the synthesis of the O-side-chain of the lipopolysaccharide, the rfb region, were cloned into plasmid pBR322 . The O-side-chain of YeO3 was expressed by the clone both in Escherichia coli and Salmonella typhimurium indicating that the entire rfb region was included in the clone . It was shown by restriction mapping, deletion analysis and transposition mutagenesis that about 10.4 kilobase pairs of DNA was essential for the synthesis and expression of the O-side-chain . The correct assembly of the O-side-chain on the cell surface of the clone was confirmed by immunofluorescence microscopy and slide agglutination . Immunoblotting using monoclonal antibody specific for the O-side-chain of YeO3 revealed that the O-side-chain material synthesized by the clone in E . coli was similar to that of YeO3 . The clone did not show the in vitro temperature variation in O-side-chain expression characteristic of YeO3 . Instead analogous O-side-chain was produced both at 25 degrees C and at 37 degrees C . Using transposon Tn2507, which carries a promotorless chloramphenicol acetyltransferase (CAT) gene, transcriptional fusions with the target DNA were generated . When testing the ability of mutated clones to produce CAT, transcription was shown to occur in a uniform direction throughout the whole rfb region . In colony hybridizations, using the cloned insert as a probe, homologous DNA was detected only in pathogenic Y . enterocolitica serotypes.

IARC Sci Publ, 1991, (105), 584 - 7
Stability of mutagenic nitrosated products of indole compounds occurring in vegetables; Tiedink HG et al.; Levels of indolylglucosinolates in Brassica vegetables correlated significantly with the amounts of N-nitroso compounds formed in these vegetables after nitrite treatment . Nitrosation of indole-3-carbinol, indole-3-acetonitrile and indole, hydrolysis products of an indolylglucosinolate, resulted in formation of nitrosated products, which were directly mutagenic to Salmonella typhimurium TA100 . The nitrosated products were unstable at pH 2 but stable at pH 8 . Experiments to elucidate the mechanisms behind these differences in stability showed an equilibrium between the nitrosated indole compound and the free compound plus nitrite.

IARC Sci Publ, 1991, (105), 558 - 63
Inhibition by fatty acids of direct mutagenicity of N-nitroso compounds; Takeda K et al.; Fatty acids inhibited the direct mutagenicity of N-nitroso compounds in Salmonella typhimurium TA1535, Escherichia coli WP2 and WPhcr-, and E . coli H/r30R (wild) and Hs30R (uvrA) . This inhibitory activity was dependent on the concentration of fatty acids, and fatty acids with longer alkyl chain were more potent . Of the N-nitroso compounds tested, alpha-hydroxy nitrosamines underwent the strongest inhibitory effect . The rate of decomposition was not changed by addition of fatty acids . The partitioning property of the mutagens was altered but not to such a degree as to explain the amount of inhibition . No significant difference in alkylating activity of the N-nitroso compounds was observed in phosphate and acetate buffers . A stronger inhibition of mutagenicity by a butylating mutagen was detected in E . coli WP2 than in WP2hcr- and in E . coli H/r30R than in Hs30R, suggesting that excision repair was a possible mechanism of inhibition . The mutagenicity and cytotoxicity of alpha-hydroxy nitrosamines in Chinese hamster V79 cells were also inhibited by acetate.

IARC Sci Publ, 1991, (105), 535 - 7
Modulation of genotoxic activity of tobacco smoke; Balansky RM et al.; Tobacco smoke (TS) caused a three- to nine-fold increase in the frequency of his+ revertants in Salmonella typhimurium TA98 but not in TA97a, TA100 or TA102 . Activation by a post-mitochondrial fraction obtained from the liver of rats pretreated with Aroclor-1254 or methylcholanthrene was required; fractions from phenobarbital-pretreated or untreated rats had no effect . Vitamins A and E, but not ascorbic acid, inhibited the TS-induced mutagenesis by up to 63%, whereas glutathione and cysteine increased it slightly . Na2SeO3, but neither CoCl2 nor caffeine, inhibited the mutagenic effect of TS by 46-56% . In Chinese hamster ovary cells, both Na2SeO3 and caffeine strongly potentiated the number of chromosomal aberrations induced by TS, while theophilline slightly reduced its clastogenic effect . Treatment of mice with TS for 60 min/day increased the frequency of micronuclei in polychromatic erythrocytes in bone marrow and in fetal liver and the number of NCE micronuclei in peripheral blood by four to five fold . Simultaneous treatment of mice with TS and Na2SeO3 reduced the clastogenic effect of TS . Ascorbic acid had no effect on clastogenicity but reduced toxicity as measured by body weight loss . Both Na2SeO3 and ascorbic acid suppressed the induction of TS-induced hyperplastic and metaplastic changes in bronchial mucosa but had no effect on the number of urethane-induced lung adenomas . Vitamins A and E and ascorbic acid may have a protective effect against the toxic and genotoxic activities of TS.

IARC Sci Publ, 1991, (105), 404 - 6
Biological and chemical properties of alkanediazotates as active species of N-nitroso compounds; Ukawa S et al.; The mutagenicity and chemical reactivity of (E)- and (Z)-potassium alkanediazotates, as precursors of corresponding alkanediazohydroxides, were investigated . In three microbial strains, Salmonella typhimurium TA1535 and Escherichia coli WP2 and WP2hcr-, the effect of changing the alkyl group on mutagenic potency was similar for (E)- and (Z)-diazotates, N-alkyl-N-nitrosoureas and alpha-hydroxynitrosamines . The capacity to alkylate nicotinamide, measured in an aqueous phosphate buffer, decreased with increasing alkyl chain length . Specific mutagenicity in S . typhimurium TA1535 was linearly related to alkylating activity . These results confirm that alkanediazohydroxides are the active alkylating species of N-nitroso compounds, and that their mutagenicity is determined by their alkylating activity.

IARC Sci Publ, 1991, (105), 339 - 42
Mutagenicity, DNA damage and DNA adduct formation by N-nitroso-2-hydroxyalkylamine and corresponding aldehydes; Scherer G et al.; The potent carcinogen N-nitrosodiethanolamine (NDELA) becomes mutagenic to Salmonella typhimurium TA98 and TA100 when activated by alcohol dehydrogenase from yeast or horse liver . Metabolic pathways different from alpha-oxidation might therefore be important for the activation of N-nitroso-2-hydroxyalkylamines such as NDELA . In an in-vitro test system (Namalva cells), neither NDELA nor N-nitrosoethyl-2-hydroxyethylamine was genotoxic, whereas the corresponding metabolites from alcohol dehydrogenase-mediated oxidation, N-nitroso-2-hydroxymorpholine and N-nitrosoethylethanalamine, induced single-strand breaks even at low doses . An immuno-slot-blot assay was used to study the formation of O6-2-hydroxyethyldeoxyguanosine in rat liver after oral administration of different N-nitroso-2-hydroxyalkylamines . When given at equimolar doses (0.375 mmol/kg), DNA hydroxyethylation was considerably lower (6.7 mumol/mol deoxyguanosine) with NDELA than with N-nitrosoethyl-2-hydroxyethylamine (48.7 mumol/mol deoxyguanosine) or N-nitrosomethyl-2-hydroxyethylamine (72.1 mumol/mol deoxyguanosine) . N-Nitroso-2-hydroxymorpholine did not form detectable levels of O6-2-hydroxyethyldeoxyguanosine.

IARC Sci Publ, 1991, (105), 244 - 52
Nitrosation of tertiary aromatic amines related to sunscreen ingredients; Loeppky RN et al.; Possible routes to the formation of the sunscreen contaminant, 2-ethylhexyl 4-N-methyl-N-nitrosoaminobenzoate, have been investigated in a study of the nitrosation chemistry of 2-ethylhexyl 4-N,N-dimethylaminobenzoate (Padimate-O) and related tertiary and secondary amines . Padimate-O and the corresponding ethyl ester nitrosate rapidly at 25 degrees C in either N2O3:ether or HNO2:HOAc to produce a mixture of alkyl 4-N-methyl-N-nitrosoaminobenzoate and alkyl 4-N,N-dimethylamino-3-nitrobenzoate, the former of which is the major product . The nitrosative dealkylation of these amines at this low temperature is unusual . Asymmetrical amines exhibit a preference for nitrosative demethylation (methyl versus ethyl or benzyl), but the cleavage ratios in N2O3:ether are time-dependent, suggesting competing mechanisms with different reactant kinetic orders . A radical cation route would explain the unusual reactivity, which may compete with the established nitrosative dealkylation mechanism . 2-Ethylhexyl 4-N-methyl-N-nitrosoaminobenzoate was mutagenic in two strains of Salmonella typhimurium in the Ames assay.

J Bacteriol, 1991 Jan, 173(1), 86 - 93
A Salmonella typhimurium virulence protein is similar to a Yersinia enterocolitica invasion protein and a bacteriophage lambda outer membrane protein; Pulkkinen WS et al.; The phoP-phoQ-regulated pagC locus is essential for full virulence and survival within macrophages of Salmonella typhimurium . The protein product, DNA sequence, and transcript of pagC were determined . The pagC locus encodes a single 188-amino-acid membrane protein that is similar to the ail-encoded eucaryotic cell invasion protein of Yersinia enterocolitica and the lom-encoded protein of bacteriophage lambda . The similarity of PagC and Ail to Lom leads us to hypothesize that Lom is a virulence protein and that bacteriophage gene transfer and lysogeny could have led to the development of proteins essential to survival within macrophages and eucaryotic cell invasion.

Infect Immun, 1991 Jan, 59(1), 449 - 52
Role of ompR-dependent genes in Salmonella typhimurium virulence: mutants deficient in both ompC and ompF are attenuated in vivo; Chatfield SN et al.; A Salmonella typhimurium strain harboring stable mutations in both ompC and ompF was constructed from the mouse-virulent strain S . typhimurium SL1344 . When administered orally to BALB/c mice the strain was attenuated, with the 50% lethal dose (LD50) reduced by approximately 1,000-fold . However, the intravenous LD50 was reduced only by approximately 10-fold . The ompC ompF mutant persisted in murine tissues for several weeks following oral challenge, and mice immunized with this mutant were well protected against challenge with virulent SL1344 . A strain harboring a stable mutation in tppB behaved in a manner similar to that of strain SL1344 in vivo, while a strain harboring mutations in ompC, ompF, and tppB behaved as an ompC ompF mutant in vivo, indicating that the tppB operon is not required for virulence in S . typhimurium.

Folia Microbiol (Praha), 1991, 36(3), 240 - 5
Elimination of plasmids pKM 101 and F'lac from Salmonella typhimurium and Escherichia coli by bisammonium salt . The effect of outer membrane pattern; Sykora P et al.; Plasmid-curing activity of N,N'-bis(decyldimethyl)-1,6-hexanediammonium dibromide, BDHD, was tested on six different plasmids in E . coli and plasmid pKM 101 in S . typhimurium . BDHD eliminated the F'lac plasmid from E . coli cells only with a low efficiency . Plasmid pKM 101 was eliminated from S . typhimurium cells significantly and this effect was dependent on an outer membrane pattern . A deep-rough mutant of S . typhimurium is completely resistant to curing activity of BDHD, while part-rough and smooth cells are susceptible to it . In contrast to pKM 101, a cryptic plasmid being present in S . typhimurium cells was not eliminated by BDHD . The curing activity of sodium dodecyl sulfate, acridine orange, crystal violet, and promethazine was also affected by the outer membrane pattern of S . typhimurium cells.

Eur J Cancer, 1991, 27(4), 478 - 82
Increased intracellular killing of bacteria in vitro by monocytes of patients with metastatic melanoma before and during treatment with interferon-gamma and interferon-alpha; Osanto S et al.; The effect of recombinant human interferon-gamma (rHuIFN-gamma) and interferon-alpha (rHuIFN-alpha) as in vivo stimuli for the activation of human monocytes was investigated on the basis of the bactericidal activity of peripheral blood monocytes in 11 patients with metastatic melanoma before and during treatment with interferons . Patients received increasing doses of rHuIFN-gamma and a fixed dose of rHuIFN-alpha, both administered subcutaneously three times a week . The rates of intracellular killing of Listeria monocytogenes and Salmonella typhimurium after in vitro phagocytosis by monocytes collected from melanoma patients before interferon treatment were increased (P less than 0.01) by a factor of 1.7 and 1.4, respectively, relative to the rate constants in blood monocytes of healthy donors . During treatment with the interferons, the rates of intracellular killing of the bacteria by patients' monocytes did not further increase . The findings underscore the immunogenicity of malignant melanoma and put into question the macrophage activating activity of IFN-gamma with respect to the bactericidal activity of monocytes.

Asia Pac J Public Health, 1991, 5(3), 256 - 61
Observations on the ecology of Salmonella waycross and Salmonella typhimurium on Guam; Haddock RL et al.; A period of high incidence of human Salmonella infections on the island of Guam saw the emergence of S . waycross as the most commonly isolated serotype as well as a concurrent decreasing proportion of isolates due to S . typhimurium . Predation of local rodents by an introduced snake is believed to account for the decreased prevalence of S . typhimurium infections, but reasons for the increased prevalence of S . waycross infections are unknown.

IARC Sci Publ, 1991, (115), 255 - 60
Mutagenicity and effects of ochratoxin A on the frequency of sister chromatid exchange after metabolic activation; Hennig A et al.; Primary cultures of hepatocytes derived from untreated rats were incubated in the presence of ochratoxin A for 24 h . Five different strains of histidine auxotroph Salmonella typhimurium were exposed to conditioned cell culture medium before being tested for mutagenicity . A clear hepatocyte-mediated mutagenic response was observed in TA1535, TA1538 and TA100 . In addition, sister chromatid exchange frequency was increased in human peripheral lymphocytes that had been incubated in the presence of conditioned medium derived from ochratoxin A-exposed hepatocytes.

J Reprod Fertil Suppl, 1991, 44, 509 - 16
Experimental models of endotoxaemia related to abortion in the mare; Kindahl H et al.; Three different routes of administering Salmonella typhimurium endotoxin to mimic naturally occurring endotoxaemia were tried in the mare . Bolus injection, repeated bolus injections and continuous low-dose infusion were compared with prostaglandin F2 alpha release, leucocyte count and clinical response . A biphasic prostaglandin release and a pronounced leucopenia of almost identical patterns were seen in all models . Repeated bolus injections showed that the second injection initiated only a small prostaglandin release indicating the development of refractoriness to the treatment . A similar refractoriness or desensitization occurred during the low-dose infusion . Flunixin meglumine, a potent inhibitor of prostaglandin biosynthesis, administered in different combinations in association with endotoxin demonstrated that this compound must be used at an early stage to prevent endotoxaemia and its deleterious effects on pregnancy . Taken together, the results show that horses are sensitive to endotoxins such that a short period of challenge (about 30 min) is enough to cause clinical signs and reproductive disorders.

Indian J Pathol Microbiol, 1991 Jan, 34(1), 22 - 5
Salmonella typhimurium isolated from bacteraemia; Suresh KP et al.; During a two year period, a total of 15 strains of S . typhimurium were isolated and analysed by phage typing . Of these, 13 were found untypable, while two strains belonged to phage 76 and 22 . All the strains were sensitive to Gentamicin and Cephaloridine . All but one showed multiple drug resistance.

Indian J Pathol Microbiol, 1991 Jan, 34(1), 17 - 21
Salmonella phage types in Bombay from 1983 to 1987; Roche RA et al.; A total of 156 strains of Salmonella isolated at T.N . Medical College and B.Y.L . Nair Ch . Hospital, Bombay over a period of 5 years from 1983 to 1987 were subjected to Phage Typing . Out of the 111 Salmonella typhi strains, phage type A was found in highest proportion (45.95%), followed by phage type E1 (15.32%), 0(9.91%), Deg . Vi . (9.91%) and C5(5.41%) . Salmonella paratyphi A had phage type pattern of 1(60.0%), 2(22.86%) and Untypable (14.29%) . Majority of the Salmonella typhimurium isolates (90.0%) were untypable.

Arch Microbiol, 1991, 156(4), 307 - 11
Prolonged environmental stress via a two step process selects mutants of Escherichia, Salmonella and Pseudomonas that grow at 54 degrees C; Droffner ML et al.; A prolonged incubation of Escherichia, Salmonella or Pseudomonas at 48 degrees C with nalidixic acid selected mutants (T48) able to grow at 48 degrees C . A prolonged incubation at 54 degrees C of the T48 mutants selected mutants (T54) able to grow at 54 degrees C . These mutants were susceptible to the same bacteriophages as the original mesophilic strains . Auxotrophic phenotypes of Escherichia coli and Salmonella typhimurium mesophilic parents were demonstrated by these mutants if they were cultivated on minimal agar with cellobiose at 48 degrees C or 54 degrees C or on a minimal agar with glucose at 37 degrees C . The T48 alleles mapped in the gyrA region of E . coli or S . typhimurium chromosome . In S . typhimurium the T54 alleles, which permit growth at 54 degrees C, were shown by cotransductional analysis to be linked to gyrA.

Arch Microbiol, 1991, 156(4), 281 - 9
Structure and expression of the Chlorobium vibrioforme hemA gene; Majumdar D et al.; The green sulfur bacterium, Chlorobium vibrioforme, synthesizes the tetrapyrrole precursor, delta-aminolevulinic acid (ALA), from glutamate via the RNA-dependent five-carbon pathway . A 1.9-kb clone of genomic DNA from C . vibrioforme that is capable of transforming a glutamyl-tRNA reductase-deficient, ALA-dependent, hemA mutant of Escherichia coli to prototrophy was sequenced . The transforming C . vibrioforme DNA has significant sequence similarity to the E . coli, Salmonella typhimurium, and Bacillus subtilis hemA genes and contains a 1245 base open reading frame that encodes a 415 amino acid polypeptide with a calculated molecular weight of 46174 . This polypeptide has over 28% amino acid identity with the polypeptides deduced from the nucleic acid sequences of the E . coli, S . typhimurium, and B . subtilis hemA genes . No sequence similarity was detected, at either the nucleic acid or the peptide level, with the Rhodobacter capsulatus or Bradyrhizobium japonicum hemA genes, which encode ALA synthase, or with the S . typhimurium hemL gene, which encodes glutamate-1-semialdehyde aminotransferase . These results establish that hemA encodes glutamyl-tRNA reductase in species that use the five-carbon ALA biosynthetic pathway . A second region of the cloned DNA, located downstream from the hemA gene, has significant sequence similarity to the E . coli and B . subtilis hemC genes . This region contains a potential open reading frame that encodes a polypeptide that has high sequence identity to the deduced E . coli and B . subtilis HemC peptides . hemC encodes the tetrapyrrole biosynthetic enzyme, porphobilinogen deaminase, in these species.(ABSTRACT TRUNCATED AT 250 WORDS)

Int J Immunopharmacol, 1991, 13(5), 541 - 8
Effect of the new immunostimulator HAB 439 on cell-mediated immunity against intracellular bacteria; Dickneite G et al.; The isoxazoline derivative HAB 439 was tested for its enzyme inhibiting potency and was found to be an inhibitor of aminopeptidase B (IC50 = 22.5 micrograms/ml) . In further immunopharmacological experiments its efficacy to stimulate cell-mediated immunity was evaluated . HAB 439 was shown to stimulate DTH-reaction against Salmonella typhimurium and Listeria monocytogenes . HAB 439 protected animals against infection by reducing the bacterial load in livers and spleens and by decreasing the mortality rate . Treatment with the antibiotic ampicillin induced a decreased DTH-reaction in mice which was demonstrated to be due to a reduction of the antigen to be presented to the immune system and not to immune suppression . HAB 439 restored the impaired immune response to S . typhimurium and L . monocytogenes in a dose-dependent way . Restoration of DTH was shown to lead to an improvement of protection in ampicillin-treated mice which were challenged with the intracellular bacteria.

Nauchnye Doki Vyss Shkoly Biol Nauki, 1991, (7), 58 - 63
{The effect of cyclooxygenase inhibition on the indices of the thrombocyte-vascular link in hemostasis and on the free-radical processes of lipid oxidation in experimental Salmonella intoxication}; Malov VA et al.; Injection of Salmonella typhimurium endotoxin to the laboratory animals (rabbits) in dose of 1 mg/ml (LD84) induces the particular changes in the thrombocyte vessels system of hemostasis: decrease of aggregatory ability of thrombocytes, increase of thromboxane A2 and prostacyclin activation of lipid peroxidation process . Use of indomethacin--the cyclooxygenase inhibitor--leads to less progressive alterations of the studied parameters of the thrombocyte vessels hemostasis and lipid peroxidation processes.

Microbios, 1991, 67(272-273), 141 - 9
Physiological effects of the lipopolysaccharide of Vibrio vulnificus on mice and rats; McPherson VL et al.; Vibrio vulnificus is a pathogenic, marine, Gram-negative bacterium which commonly enters and infects humans via open wounds or the ingestion of raw seafood . The lipopolysaccharide (LPS) of V . vulnificus has recently been characterized, but the biological activity of this putative endotoxin is unknown . Three treatment groups were used to test its activity: saline (negative control), the LPS of Salmonella typhimurium (a known endotoxin), and the LPS of V . vulnificus . Whereas, intravenous injections of the S . typhimurium LPS caused mortality in two strains of mice, V . vulnificus LPS was not lethal . However, intraperitoneal injections into rats of both V . vulnificus and S . typhimurium LPS were pyrogenic . Intravenous injections of V . vulnificus LPS in rats caused decreased mean arterial pressure within 10 min which further declined, leading to death in 30 to 60 min . S . typhimurium LPS caused similar responses at the same concentration . The data suggest that the LPS of V . vulnificus may be a factor contributing to the virulence of this organism.

Free Radic Biol Med, 1991, 11(6), 545 - 55
Does hydrogen peroxide exist "free" in biological systems?
Schubert J, Wilmer JW.
Hydrogen peroxide (H2O2) can diffuse far from the site of production to intracellular locations where biological effects may be greater . The diffusion range is extended by H2O2 carriers formed spontaneously by hydrogen bonding with monomeric and polymeric compounds, including amino and dicarboxylic acids, peptides, proteins, nucleic acid bases, and nucleosides . Hydrogen peroxide adducts (HPAs) are readily synthesized, e.g., crystalline histidine (His)-H2O2 adducts . An equilibrium exists between an adduct-forming compound and H2O2 . The detection and relative stabilities of HPAs are measured by the degree of decomposition of H2O2 as influenced by test compounds in buffered solution competing with glucose or fructose for H2O2 . The HPAs delay decomposition of H2O2 up to several hundredfold . The overall charge on an HPA, i.e., its ability to penetrate cell membranes, influences the cytotoxic and clastogenic effects of H2O2 . Growth inhibition of Salmonella typhimurium LT2 by H2O2 is enhanced by neutral HPAs but decreased by anionic HPAs . Addition of catalase 1, 10, or 30 min after inoculation of S . typhimurium LT2 reduces or nearly eliminates partial growth inhibition by H2O2, but a neutral HPA, especially His-H2O2, transported H2O2 into the cells within 1 min, and in about 10 min completely inhibited growth . The stability of HPAs decreases with increasing pH or increasing temperature, while added Fe(II) in the presence and absence of EDTA accelerates H2O2 and HPA decomposition . Calculations indicate H2O2 hydrogen bonds with nucleic acid-base pairs with no apparent bond strain and energy stabilization comparable to normal hydrogen bonding.

J Biochem Toxicol, 1991 Winter, 6(4), 277 - 82
Purified NAD(P)H-quinone oxidoreductase enhances the mutagenicity of dinitropyrenes in vitro; Hajos AK et al.; The effect of highly purified rat liver cytosolic NAD(P)H-quinone oxidoreductase {EC 1.6.99.2} on the mutagenicity of 1,3- 1,6- and 1,8-dinitropyrene (DNP) was studied in the Ames Salmonella typhimurium mutagenicity assay . NAD(P)H-quinone oxidoreductase over the range of 0.02-0.8 micrograms/plate (38-1500) units increased up to threefold the mutagenicity of all three DNPs in S . typhimurium TA 98 . In TA98NR, a strain deficient in "classical" nitro-reductase, the mutagenicity of 1,6- and 1,8-DNP was essentially unchanged, whereas that of 1,3-DNP was markedly reduced . NAD(P)H-quinone oxidoreductase enhanced the mutagenicity of 1,6- and 1,8-DNP to approximately equivalent extents in TA98NR and TA98 . The mutagenicity of 1,3-DNP in TA98NR was potently enhanced by the addition of NAD(P)H-quinone oxidoreductase in a dose-responsive manner . In the presence of 0.8 micrograms NAD(P)H-quinone oxidoreductase, 1,3-DNP displayed a mutagenic response in TA98NR that was comparable to that obtained in TA98 . NAD(P)H-quinone oxidoreductase was found to increase the mutagenicity of 1,6- but not 1,3- or 1,8-DNP to mutagenic intermediates in TA98/1,8-DNP6, a strain deficient in O-acetyltransferase activity . The results suggest that NAD(P)H-quinone oxidoreductase not only catalyzes reduction of the parent DNP but also that of partially reduced metabolites generated from that DNP . Such reductive metabolism may lead to increased formation of the penultimate mutagenic species.

Int Arch Allergy Appl Immunol, 1991, 96(2), 161 - 7
Delayed-type hypersensitivity antigens detected in culture supernatants of Salmonella typhimurium; Cho N et al.; Protein antigens eliciting delayed type hypersensitivity (DTH) were analyzed and purified from the supernatants of protein-free cultures in which Salmonella typhimurium TV148 organisms had grown . DTH activity was measured by the footpad swelling test in mice immunized with living organisms of S . typhimurium TV148 or Escherichia coli K-12 . DTH activity in the culture supernatant was specific to TV148-immunized mice . This activity was destroyed by pronase . DTH activity was unable to pass through an ultrafilter with an exclusion limit of 10 kD . After condensation of the supernatant and following centrifugation (100,000 g for 1 h), the DTH activities of the sediment and the supernatant were examined, and both showed DTH activity . Further analyses of DTH antigens in the supernatant by HPLC gel filtration separated the activity into three portions . The most active portion was further fractionated by hydroxyapatite HPLC, revealing the presence of two DTH antigens, with molecular weights of 65 and less than 10 kD . These results indicate that the culture supernatant of S . typhimurium TV148 organisms contains a variety of macromolecular protein DTH-eliciting antigens, and one of the antigens is 65 kD, which is dissociated partly by organic solvents into a low molecular weight (less than 10 kD) antigen.

Environ Mol Mutagen, 1991, 18(4), 224 - 30
Analysis of Salmonella typhimurium hisD3052 revertants: the use of oligodeoxyribonucleotide colony hybridization, PCR, and direct sequencing in mutational analysis; Kupchella E et al.; A rapid method for determining the DNA sequences of Salmonella typhimurium hisD3052 revertants is presented . DNA colony hybridization was used to analyze revertants previously studied by Isono and Yourno {Proc Natl Acad Sci USA 71:1612-1617, 1974} . Synthetic oligodeoxyribonucleotide probes (18-mers) were able to distinguish sequences that differed by a single base pair . Mutant his sequences not identified by probing analysis were amplified using polymerase chain reaction (PCR) and directly sequenced . The combined use of DNA-colony hybridization and direct sequencing offers a precise and rapid means for the molecular characterization of hisD3052 revertants.

Arch Toxicol, 1991, 65(8), 633 - 9
DNA binding, adduct characterisation and metabolic activation of aflatoxin B1 catalysed by isolated rat liver parenchymal, Kupffer and endothelial cells; Schlemper B et al.; In vitro studies with rat liver parenchymal, Kupffer and endothelial cells isolated from male Sprague-Dawley rats were undertaken to investigate cell-specific bioactivation of aflatoxin B1, DNA binding and adduct formation . In the mutagenicity studies, using homogenates of all three separated liver cell populations (co-incubated with NADP+ and glucose-6-phosphate as cofactors for the cytochrome P-450 monooxygenase system) parenchymal, Kupffer and endothelial cells were able to activate aflatoxin B1 to a metabolite mutagenic to Salmonella typhimurium TA 98 . In the case of nonparenchymal cells (i.e . Kupffer and endothelial cells) 10-fold higher concentrations of aflatoxin B1 had to be used to obtain a similar number of revertants to that observed with parenchymal cells . Induction studies with Aroclor 1254 led to a striking decrease in the activation of aflatoxin B1 in parenchymal cells, whereas nonparenchymal cells had a slightly enhanced metabolic activation capacity for aflatoxin B1 . Metabolism studies with microsomes from induced and noninduced cells using testosterone as substrate revealed comparable results: after induction with Aroclor 1254, parenchymal cells showed a 60% decrease in the formation rate of 2 alpha-hydroxytestosterone, whereas the formation rate of this metabolite remained unchanged in nonparenchymal cells; 2 alpha-hydroxytestosterone is specifically formed by cytochrome P-450 IIC11, which also catalyses the activation of aflatoxin B1 to its epoxide . When freshly isolated, intact cells were incubated with tritiated aflatoxin B1, a dose-dependent aflatoxin B1 binding to DNA in parenchymal and nonparenchymal cells was observed . HPLC analysis of DNA acid hydrolysates of all three cell types showed the major adduct to be 8,9-dihydro-8-(N7-guanyl)-9-hydroxy-aflatoxin B1.

Folia Microbiol (Praha), 1991, 36(3), 317 - 8
Colicin E1 export in Salmonella typhimurium wild-type and lipopolysaccharide mutants; Viejo BM et al.; Colicin export was studied in different Salmonella typhimurium strains lacking the O-antigen repeating units (O-) and different strains with different chemotypes for the lipopolysaccharide core, as well as the wild-type strain (O+), to determine the role of lipopolysaccharide length on colicin E1 export . While the lipopolysaccharide length influences the levels of external hemolytic activity in S . typhimurium, no effect was detected on colicin E1 export.

Biotech Histochem, 1991, 66(6), 307 - 15
Decontamination of aqueous solutions of biological stains; Lunn G et al.; Aqueous solutions of a number of biological stains were completely decontaminated to the limit of detection using Amberlite resins . Amberlite XAD-16 was the most generally applicable resin but Amberlite XAD-2, Amberlite XAD-4, and Amberlite XAD-7 could be used to decontaminate some solutions . Solutions of acridine orange, alcian blue 8GX, alizarin red S, azure A, azure B, Congo red, cresyl violet acetate, crystal violet, eosin B, erythrosin B, ethidium bromide, Janus green B, methylene blue, neutral red, nigrosin, orcein, propidium iodide, rose Bengal, safranine O, toluidine blue O, and trypan blue could be completely decontaminated to the limit of detection and solutions of eosin Y and Giemsa stain were decontaminated to very low levels (less than 0.02 ppm) using Amberlite XAD-16 . Reaction times varied from 10 min to 18 hr . Up to 500 ml of a 100 micrograms/ml solution could be decontaminated per gram of Amberlite XAD-16 . Fourteen of the 23 stains tested were found to be mutagenic to Salmonella typhimurium . None of the completely decontaminated solutions were found to be mutagenic.

Acta Microbiol Pol, 1991, 40(1-2), 65 - 70
Impaired bactericidal activity of serum of a child suffering from focal proliferative glomerulonephritis; Jankowski S et al.; The serum of a child with focal proliferative glomerulonephritis was found to exhibit a weaker bactericidal activity against Pseudomonas aeruginosa, Salmonella typhimurium, Salmonella enteritidis and Escherichia coli strains as compared with sera of the child's parents . The child's serum showed a low haemolytical activity of complement as well as a low C3 concentration . The authors believe that the abnormal complement concentration could cause the impaired bactericidal activity of the patient serum.

Lab Delo, 1991, (11), 60 - 3
{DNAase activity, a method of differentiating hospital strains of Salmonella typhimurium}; Lysov PS et al.; Measurements of DNAse activities in Salmonella typhimurium strains of various origins have demonstrated that hospital strains are characterized by the highest DNAse activity . This activity correlates with the presence of R-plasmids in the cells . High DNAse activity of hospital strains is a stable marker, and therefore may be used for intraspecies differentiation of S . typhimurium.

J Bacteriol, 1991 Jan, 173(1), 234 - 44
Identification and characterization of dppA, an Escherichia coli gene encoding a periplasmic dipeptide transport protein; Olson ER et al.; We describe the isolation and analysis of an Escherichia coli gene, dppA, and its role in dipeptide transport . dppA maps near min 79 and encodes a protein (DppA) that has regions of amino acid similarity with a peptide-binding protein from Salmonella typhimurium (OppA) . Like OppA, DppA is found in the periplasmic space and thus is most likely a dipeptide-binding protein . Insertional inactivation of dppA results in the inability of a proline auxotroph to utilize Pro-Gly as a proline source . dppA-dependent Pro-Gly utilization does not require any of the three major proline transport systems, demonstrating that DppA is not simply a dipeptidase . An in vivo competition assay was used to show that DppA is probably involved in the transport of dipeptides other than Pro-Gly . Transcription of dppA is repressed by the presence of casamino acids, suggesting that the cell alters its dipeptide transport capabilities in response to an environmental signal.

Teratog Carcinog Mutagen, 1991, 11(2), 65 - 76
Analysis of rat lymphocyte activation of benzo{a}pyrene, 2-acetylaminofluorene, and several of their metabolites to mutagenic and DNA-damaging species in vitro; Gao N et al.; Rat lymphocytes are a potentially useful and convenient cell system for monitoring the genotoxic effects of chemicals in vivo, but little is known about the ability of these cells to metabolize promutagens to genotoxic species . In this study, Fischer 344 rat lymphocytes were treated in vitro with benzo{a}pyrene (BaP), 2-acetylaminofluorene (2-AAF), and several of their metabolites, and DNA damage was measured using nucleoid sedimentation analysis . Of the BaP derivatives, BaP 4,5-oxide and BaP 7,8-diol-9, 10-epoxide decreased lymphocyte nucleoid sedimentation, whereas BaP and BaP 7,8-dihydrodiol had little effect . Among the 2-AAF derivatives, N-acetoxy-2-AAF, N-hydroxy-2-AAF, and N-hydroxy-2-aminofluorene damaged rat lymphocyte nucleoids, whereas 2-AAF, 2-aminofluorene, and fluorene produced little detectable damage . The decrease in nucleoid sedimentation produced by N-hydroxy-2-AAF was not inhibited by paraoxon, salicylamide, or 2-aminofluorene, whereas paraoxon inhibited damage produced by N-acetoxy-2-AAF . In co-culture assays, rat lymphocytes increased the mutagenicity of N-hydroxy-2-AAF in Salmonella typhimurium strain TA98, but mediated little or no mutagenic response with BaP, BaP 7,8-dihydrodiol, and 2-AAF . Also, human lymphocytes, but not rat lymphocytes, mediated a positive mutagenic response with BaP 7,8-dihydrodiol in Chinese hamster ovary UV5 cells . Although rat lymphocytes may metabolize certain proximal genotoxic chemicals to DNA-damaging species (e.g., N-hydroxy-2-AAF), these data suggest that in vivo lymphocyte DNA damage is more likely to result from lymphocytes encountering reactive chemical derivatives produced by other cells . It is also clear that differences exist between the ability of human and rat lymphocytes to activate promutagens, and this may impact on the use of the rat model to predict the genotoxicity of chemicals in humans.

Teratog Carcinog Mutagen, 1991, 11(2), 103 - 14
DNA strand breaks induced in cultured human and rodent cells by chlorohydroxyfuranones--mutagens isolated from drinking water; Chang LW et al.; Chlorohydroxyfuranones, by-products of chlorine disinfection and drinking water contaminants, are shown to produce DNA strand breaks in human and rodent cells . One chlorohydroxyfuranone, 3-chloro-4-dichloromethyl-5-hydroxy-2{5H}-furanone (MX), a potent bacterial mutagen, induces 232 +/- 89 DNA strand breaks.(cell-microM)-1 in human CCRF-CEM cells over a concentration range of 4.4 to 220 microM . This constitutes a DNA damage potency comparable to dimethylsulfate (DMS) . By comparison, 3,4-dichloro-5-hydroxy-2{5H}-furanone (MA), another chlorohydroxyfuranone which is approximately four orders of magnitude less mutagenic than MX in Salmonella typhimurium strain TA100, is only about tenfold less potent as an inducer of DNA strand breaks in these cells, i.e., 18.2 +/- 3.1 strand breaks.(cell-microM)-1 . The DNA strand-breaking potential of MX is inactivated by prior incubation with a rat liver S9 homogenate . In addition, both chlorohydroxyfuranones are ineffective at producing DNA strand breaks in primary rate hepatocytes (PRH) at concentrations below those which produce cytotoxicity as assessed by release of the cellular enzyme lactate dehydrogenase (LDH) . Prior treatment of the PRH with 750 microM diethyl maleate, a glutathione-depleting agent, did not enhance the cytotoxicity nor the DNA strand-breaking potential of either chlorohydroxyfuranone . This could indicate that glutathione-glutathione-S-transferase is not an important mechanism for the detoxification of these compounds in PRH.

Teratog Carcinog Mutagen, 1991, 11(1), 55 - 60
A genotoxicological study of hexachlorobenzene and pentachloroanisole; Siekel P et al.; The potential mutagenic activity of hexachlorobenzene (HCB) and pentachloroanisole (PCA) was investigated . No genotoxicity after application on Salmonella typhimurium (Ames test), Escherichia coli, and human peripheral blood lymphocytes in vitro was observed.

Acta Derm Venereol, 1991, 71(1), 77 - 9
Sweet's syndrome associated with Salmonella typhimurium infection; Zillikens D et al.; A 41-year-old woman presented with the typical clinical and pathohistological features of acute febrile neutrophilic dermatosis (AFND) . The disease had been preceded by diarrhoea and vomiting for 2 weeks . Stool cultures proved positive for Salmonella typhimurium infection . Antibiotic therapy and tapering oral steroids led to a complete remission of skin lesions within 2 weeks . To our knowledge, this is the first report of Sweet's syndrome associated with salmonellosis.

Boll Ist Sieroter Milan, 1991-92, 70(1-2), 505 - 12
Survival of bacteriophage 1 of the Salmonella typhimurium phage typing scheme in 4 different types of sterile soil; Leonardopoulos J et al.; The survival of bacteriophage 1 of the Salmonella typhimurium phage typing scheme was studied in four different types of sterile soil at 4.20 and 37 degrees C . The longevity of the phage was generally short, not exceeding 36 days and depended on the temperature and the type of soil.

Biochemistry, 1990 Dec 25, 29(51), 11280 - 92
Catalytic activities of human liver cytochrome P-450 IIIA4 expressed in Saccharomyces cerevisiae; Brian WR et al.; A human liver cytochrome P-450 (P-450) IIIA4 cDNA clone was inserted behind an alcohol dehydrogenase promoter in the plasmid vector pAAH5 and expressed in Saccharomyces cerevisiae (D12 and AH22 strains) . A cytochrome P-450 with typical spectral properties was expressed at a level of approximately 8 x 10(5) molecules/cell in either strain of yeast . The expressed P-450 IIIA4 had the same apparent monomeric Mr as the corresponding protein in human liver microsomes (P-450NF) and could be isolated from yeast microsomes . Catalytic activity of the yeast microsomes toward putative P-450 IIIA4 substrates was seen in the reactions supported by cumene hydroperoxide but was often lower and variable when supported by the physiological donor NADPH . The catalytic activity of purified P-450 IIIA4 was also poor in some systems reconstituted with rabbit liver NADPH-P-450 reductase and best when both the detergent 3-{(3-cholamidopropyl)dimethylammonio}-1-propanesulfonate and a lipid extract (from liver or yeast microsomes) or L-alpha-1,2-dilauroyl-sn-glycero-3-phosphocholine were present . Under these conditions the expressed P-450 IIIA4 was an efficient catalyst for nifedipine oxidation, 6 beta-hydroxylation of testosterone and cortisol, 2-hydroxylation of 17 beta-estradiol and 17 alpha-ethynylestradiol, N-oxygenation and 3-hydroxylation of quinidine, 16 alpha-hydroxylation of dehydroepiandrosterone 3-sulfate, erythromycin N-demethylation, the 10-hydroxylation of (R)-warfarin, the formation of 9,10-dehydrowarfarin from (S)-warfarin, and the activation of aflatoxins B1 and G1, sterigmatocystin, 7,8-dihydroxy-7,8-dihydrobenzo{a}pyrene (both + and - diastereomers), 3,4-dihydroxy-3,4-dihydrobenz{a}anthracene, 3,4-dihydroxy-3,4-dihydro-7, 12-dimethylbenz{a}anthracene, 9,10-dihydroxy-9,10-dihydrobenzo{b}fluoranthene, 6-aminochrysene, and tris(2,3-dibromopropyl) phosphate to products genotoxic in a Salmonella typhimurium TA1535/pSK1002 system where a chimeric umuC' 'lacZ plasmid is responsive to DNA alkylation . Reaction rates were stimulated by 7,8-benzoflavone and inhibited by rabbit anti-P-450 IIIA (anti-P-450NF), troleandomycin, gestodene, and cimetidine . Evidence was obtained that rates of reduction of ferric P-450 IIIA4 in yeast microsomes and the reconstituted systems are slow and at least partially responsible for the lower rates of catalysis seen in these systems (relative to liver microsomes) . The results of these studies with a defined protein clearly demonstrate the ability of P-450 IIIA4 to catalyze regio- and stereoselective oxidations with a diverse group of substrates, and this enzyme appears to be one of the most versatile catalysts in the P-450 family.

J Mol Biol, 1990 Dec 20, 216(4), 897 - 910
TonB protein of Salmonella typhimurium . A model for signal transduction between membranes; Hannavy K et al.; The tonB gene product is required for several outer membrane transport processes in bacteria . The tonB gene from Salmonella typhimurium was sequenced and found to be similar to that of Escherichia coli . The TonB protein is highly proline-rich and includes an unusual segment consisting of multiple X-Pro dipeptide repeats . A synthetic peptide corresponding to this segment has been used to raise anti-TonB antibodies . TonB was shown to be associated with the cytoplasmic membrane, apparently anchored via a single hydrophobic N-terminal segment . Protease accessibility studies, and the use of a series of TonB-beta-lactamase fusions, showed that the rest of the TonB protein is periplasmic . Unusually, export of TonB is not accompanied by cleavage of the N-terminal signal peptide . In the accompanying paper, we show that TonB interacts directly with the outer membrane FhuA (TonA) receptor . Thus, TonB must span the periplasm, providing a link between the cytoplasmic membrane and receptors in the outer membrane . On the basis of these data, and those published by other laboratories, we propose a model whereby TonB serves as a "mechanical" linkage that, by transmitting protein conformational changes from the cytoplasmic membrane across the periplasm, acts as a means of coupling energy to outer membrane transport processes . Such a mechanism has general implications for signal transduction within and between proteins.

J Mol Biol, 1990 Dec 20, 216(4), 883 - 95
Structure and function of X-Pro dipeptide repeats in the TonB proteins of Salmonella typhimurium and Escherichia coli; Brewer S et al.; The TonB protein is required for several outer membrane transport processes in bacteria . A short 33-residue peptide segment of TonB has been studied by 1H and 13C nuclear magnetic resonance spectroscopy . The sequence of this peptide segment contains multiple Glu-Pro and Lys-Pro dipeptide repeats that maintain rigid, elongated structures and flank a short connecting segment that adopts a beta-strand configuration . This TonB peptide is shown to interact specifically with the FhuA protein, the outer membrane receptor for ferrichrome-iron, providing the first direct evidence that the TonB protein interacts with outer membrane receptors . Interaction with the FhuA protein involves the extended structural element containing positively charged Lys-Pro repeats, and suggests a functional role for this segment of the TonB protein . As TonB is anchored in the cytoplasmic membrane the protein must, uniquely, span the periplasm . These data, together with studies described in the accompanying paper, suggest a model by which TonB serves to transduce conformational information over extended distances, from the cytoplasmic membrane to the outer membrane.

Toxicology, 1990 Dec 17, 65(1-2), 1 - 22
Genotoxicity evaluation of lithium hypochlorite; Weiner ML et al.; Lithium hypochlorite (LiOCl), the pool and spa sanitizer/algicide, was evaluated for genotoxicity in a battery of studies designed to evaluate potential mutagenicity, DNA damage and chromosome aberrations . LiOCl was not mutagenic in the Ames test when tested in Salmonella typhimurium strains TA98, TA100, TA1535, TA1537, TA1538 or in the hypoxanthine-guanine phosphoribosyl transferase (HGPRT) mutation assay in Chinese hamster ovary (CHO) cells without metabolic activation . LiOCl did not induce DNA damage in the unscheduled DNA synthesis assay using rat primary hepatocytes . Effects on metaphase chromosomes were evaluated in vitro in CHO cells at 12 and 18 h exposure without S9 and at 12 and 22 h following a 2 h exposure with S9 . LiOCl induced a statistically significant increase in chromosome aberrations at the high dose only at both harvest times without S9 and at the late harvest time with S9 . There were significant increases in chromosome aberrations at the low dose, low-mid and high doses, but not at the high mid-dose at the early harvest time with S9 . However, LiOCl did not increase chromosome aberrations when tested orally in rats at maximally tolerated doses . Bone marrow cells, collected 6, 24 and 48 h after a single oral dose of LiOCl to rats (100, 500, 1000 mg/kg in males; 50, 250, 500 mg/kg in females) showed no increase in the incidence of aberrations . In general, the weight of the evidence indicates that LiOCl is not genotoxic.

J Immunol, 1990 Dec 15, 145(12), 4317 - 21
Hepatitis B virus nucleocapsid/pre-S2 fusion proteins expressed in attenuated Salmonella for oral vaccination; Schodel F et al.; Hybrid HBV nucleocapsid-pre-S(2) fusion proteins were stably expressed in several aromatic-dependent attenuated Salmonella typhimurium and Salmonella dublin strains . When these live recombinant bacteria were administered i.p . to BALB/c mice they induced high titer anti-hepatitis B virus core Ag (HBc) and detectable anti-pre-S2 serum antibodies . Upon oral feeding of the recombinant salmonellae to mice, the rate of seroconversion to anti-HBc was dependent on the salmonella strain used . With the best carrier strain high titer anti-HBc antibodies and lower titer anti-pre-S2 serum IgG antibodies were observed two weeks after a single oral immunization . The Ig class and IgG subclass distribution of anti-HBc antibodies after i.p . and oral immunization is consistent with the induction of functional T cell help.

Cancer Res, 1990 Dec 15, 50(24), 7789 - 92
Activation of mitomycin C by NADPH:cytochrome P-450 reductase; Bligh HF et al.; Mitomycin C is an alkylating agent used in cancer chemotherapy that shows some specificity towards hypoxic cells . The therapeutic effects of this compound are thought to result from its metabolic activation by enzymes such as NADPH:cytochrome P-450 reductase . In a previous report we described a Chinese hamster ovary cell line resistant to mitomycin C, which had a decreased NADPH:cytochrome P-450 reductase activity coupled with a lower rate of mitomycin C metabolism . In order to provide further evidence that the lower reductase activity is a factor in the resistance mechanism, we incorporated NADPH:cytochrome P-450 reductase into cytotoxicity assays and showed that it significantly sensitizes cells to mitomycin C . Also, the difference in drug sensitivity between the wild-type and drug-resistant Chinese hamster ovary cells was no longer observed . In addition to these studies, we expressed a rat liver NADPH:cytochrome P-450 reductase cDNA in a Salmonella typhimurium strain, LR5000 . The bacteria expressing the rat NADPH: cytochrome P-450 reductase showed increased sensitivity to mitomycin C when incubated with this compound under aerobic conditions . However, under hypoxic conditions increased sensitivity was not observed . This parallels the previous finding with mitomycin C-resistant Chinese hamster ovary cells . These data provide direct evidence for the role of NADPH:cytochrome P-450 reductase in the cytotoxic action of this mitomycin C under aerobic but not hypoxic conditions and suggest that reduced levels of this enzyme can lead to drug resistance . P-450 reductase expressed in S . typhimurium may provide a valuable tool for evaluating the role of this enzyme in the toxicity of drugs activated through a one electron reduction pathway.

Eur J Biochem, 1990 Dec 12, 194(2), 655 - 61
Purification and fractionation of lipopolysaccharide from gram-negative bacteria by hydrophobic interaction chromatography; Fischer W; By hydrophobic interaction chromatography on octyl-Sepharose, lipopolysaccharide (LPS) of Escherichia coli Re mutant and of wild-type smooth-form (S-form) Salmonella typhimurium and Salmonella abortus equi is fractionated according to increasing amount of fatty acids . Thereby a fractionation of S-form LPS according to the length of the O-polysaccharide chain also occurs, because with increasing of fatty acids there is a decrease in the mean length of the O-polysaccharide chain from approximately 30 to 4 repeating units . Molecular species of Re-mutant LPS contain four 3-hydroxytetradecanoyl residues in addition to which dodecanoic, tetradecanoic and possibly hexadecanoic acid, appear in this sequence . Among the molecular species of S-form LPS, dodecanoic, tetradecanoic and hexadecanoic acids appear in the same order, but in contrast to Re-mutant LPS a significant fraction of S-form LPS contains less than four 3-hydroxytetradecanoyl residues . Hydrophobic interaction chromatography also proved an effective one-step purification procedure of LPS as was shown with a crude preparation from S-form S . typhimurium.

Eur J Biochem, 1990 Dec 12, 194(2), 573 - 8
Cloning, nucleotide sequence and regulation of the Salmonella typhimurium pyrD gene encoding dihydroorotate dehydrogenase; Frick MM et al.; The Salmonella typhimurium pyrD gene encoding dihydroorotate dehydrogenase was cloned and sequenced . In total, a sequence of 1286 nucleotide pairs was determined wherein a single open-reading-frame of 1011 bp, encoding a polypeptide of 336 amino acids having 95% similarity with the Escherichia coli pyrD gene product, was identified . A region of hyphenated-dyad symmetry exists within the leader region affording the potential for the formation of a stable secondary structure in the 5' end of the transcript . Mutations from several regulatory mutants were located within the region of dyad symmetry which would impart changes in the transcript within the putative secondary structure, implicating the secondary structure in regulation . Primer extension analysis revealed multiple transcriptional start sites located six to nine nucleotides downstream from the Pribnow box, with the primary initiation site differing in repressing and derepressing growth conditions . The results are discussed in terms of a translational attenuation model for regulation of pyrD expression.

Changgeng Yi Xue Za Zhi, 1990 Dec, 13(4), 290 - 5
{Epidemiology and clinical evaluation of Salmonella enteritis}; Suen TY et al.; There was a local epidemic of Salmonella enteritis in southern part of Taiwan during the summer of 1989 . From July through September 1989, a total 162 cases of enteritis were analysed in Chang Gung Memorial Hospital, Kaohsiung . Among them, 46 cases were proved to be Salmonella enteritis by stool and/or blood culture . The identified flora group mainly group B (Salmonella typhimurium, 87%), group C (Salmonella choleraesuis, 6.5%) and group D (Salmonella enteritidis, 6.5%) . The drug resistance of Salmonella enteritis of traditional antibiotics such as ampicillin, chloramphenicol and trimethoprim-Sulfamethoxazole (TMP-SMX) in apparently increasing . We found that 43.5% of cases were uniformly resistant to all 3 antimicrobial agents as mentioned above . Of the 4 infants who developed bacteremia, 2 were less than 3 months old and their blood culture grew out group B . Salmonella, but fortunately no complication were found during hospitalization . The other 2 cases were proved to be caused by group C Salmonella which was reported to have higher incidence of ensuing bacteremia . This study revealed that persistent bacteremia could be present in the absence of fever and toxic signs . Newer, third generation cephalosporins such as cefotaxime of ceftriaxone should be initiated promptly.

Int J Food Microbiol, 1990 Dec, 11(3-4), 195 - 204
Use of polymyxin-coated polyester cloth in the enzyme immunoassay of Salmonella lipopolysaccharide antigens; Blais BW et al.; Polyester cloth coated with polymyxin B was used to capture Salmonella typhimurium lipopolysaccharide antigens which were then quantitatively or qualitatively assayed using a specific antibody-peroxidase conjugate . This simple, rapid method can be used to assay a large number of samples by employing a large sheet of the polymyxin-coated cloth onto which multiple samples can be blotted . The method is reproducible and economical, since polymyxin B is relatively inexpensive, stable and available in pure form.

J Clin Microbiol, 1990 Dec, 28(12), 2597 - 601
Outbreak of Salmonella typhimurium infection traced to contaminated chocolate and caused by a strain lacking the 60-megadalton virulence plasmid; Kapperud G et al.; We describe an outbreak of Salmonella typhimurium infection, caused by contaminated chocolate produced by one Norwegian company, which occurred in Norway and Finland in 1987 . A total of 349 bacteriologically verified cases were recorded in Norway, and 12 cases were recorded in Finland . There was a predominance of young children among the patients (median age, 6 years), many of whom developed acute hemorrhagic diarrhea . The outbreak strain exhibited a rare phage lysis pattern and a characteristic plasmid profile lacking the 60-MDa virulence-associated plasmid . DNA hybridization failed to demonstrate any DNA sequence homology between the outbreak strain and the virulence plasmid . The outbreak strain was nonlethal for orally infected mice . The finding of only less than or equal to 10 S . typhimurium cells per 100 g of chocolate in about 90% of the positive samples obtained from retail outlets suggested that an inoculum of fewer than 10 organisms may have been sufficient to cause symptomatic disease.

Mutat Res, 1990 Dec, 245(4), 251 - 7
N-2 acetylation of 2'-deoxyguanosine by coffee mutagens, methylglyoxal and hydrogen peroxide; Nukaya H et al.; Coffee shows direct-acting mutagenicity in Salmonella typhimurium TA100 and most of this mutagenicity is due to the synergistic effects of methylglyoxal and hydrogen peroxide . The modifications of deoxyribonucleosides by methylglyoxal plus hydrogen peroxide were studied in vitro . When 2'-deoxyguanosine (6.25 mumole) was treated with methylglyoxal (125 mumole) and hydrogen peroxide (125 mumole) in 5 ml of 0.1 M phosphate buffer (pH 7.4) at 37 degrees C for 3 h, N2-acetyl-2'-deoxyguanosine was formed with a yield of 1.1% . Its formation increased time-dependently . By contrast, no appreciable modification of other deoxynucleosides was detected after their incubation with methylglyoxal and hydrogen peroxide under similar conditions . N2-Acetyl-2'-deoxyguanosine was also formed during incubation of 2'-deoxyguanosine with instant coffee.

Mol Gen Genet, 1990 Dec, 224(3), 364 - 72
The VANA glycopeptide resistance protein is related to D-alanyl-D-alanine ligase cell wall biosynthesis enzymes; Dutka-Malen S et al.; Inducible resistance to the glycopeptide antibiotics vancomycin and teicoplanin is mediated by plasmid pIP816 in Enterococcus faecium strain BM4147 . Vancomycin induced the synthesis of a ca . 40 kDa membrane-associated protein designated VANA . The resistance protein was partially purified and its N-terminal sequence was determined . A 1761 bp DNA restriction fragment of pIP816 was cloned into Escherichia coli and sequenced . When expressed in E . coli, this fragment encoded a ca . 40 kDa protein that comigrated with VANA from enterococcal membrane fractions . The ATG translation initiation codon for VANA specified the methionine present at the N-terminus of the protein indicating the absence of signal peptide processing . The amino acid sequence deduced from the sequence of the vanA gene consisted of 343 amino acids giving a protein with a calculated Mr of 37,400 . VANA was structurally related to the D-alanyl-D-alanine (D-ala-D-ala) ligases of Salmonella typhimurium (36% amino acid identity) and of E . coli (28%) . The vanA gene was able to transcomplement an E . coli mutant with thermosensitive D-ala-D-ala ligase activity . Thus, the inducible resistance protein VANA was structurally and functionally related to cytoplasmic enzymes that synthesize the target of glycopeptide antibiotics . Based on these observations we discuss the possibility that resistance is due to modification of the glycopeptide target.

Carcinogenesis, 1990 Dec, 11(12), 2275 - 9
In vitro inhibition of dihydropyridine oxidation and aflatoxin B1 activation in human liver microsomes by naringenin and other flavonoids; Guengerich FP et al.; Recent in vivo studies in humans have shown a dramatic effect of grapefruit juice in blocking the oxidation of dihydropyridine calcium channel blockers . The flavonoid naringin is the most abundant natural product specific for grapefruit and related citrus--the aglycone naringenin, known to be readily formed from naringin in humans, was found to inhibit the oxidation of the dihydropyridines nifedipine and felodipine in human liver microsomal preparations . These observations were of interest in light of the knowledge that the same human liver cytochrome P450 (IIIA4) appears to be a major catalyst in both nifedipine oxidation and aflatoxin B1 activation . Several flavones inhibited the in vitro activation of aflatoxin B1 in a system employing umuC gene activation due to DNA damage in Salmonella typhimurium TA1535/pSK1002, with naringenin being as effective as any . The high concentration of derivatives of naringenin in certain citrus fruits may be of relevance to cancer chemoprevention involving those carcinogens that are activated by cytochrome P-450IIIA4.

Carcinogenesis, 1990 Dec, 11(12), 2171 - 7
Potent genotoxicity of halogen lamps, compared to fluorescent light and sunlight; De Flora S et al.; The light emitted by halogen lamps induced mutations in Salmonella typhimurium and DNA damage in Escherichia coli, as shown by the hypersensitivity of DNA repair-deficient strains . The mutagenicity of halogen lamps was considerably higher than that of fluorescent light and of sunlight, even at much lower illuminance levels . Excision mechanisms and SOS functions were involved in repairing light-induced base-pair substitutions and frameshift errors in bacterial DNA . At variance with solar irradiation, which produces mutagenic effects over a wide UV spectrum, genotoxicity of halogen lamps was almost exclusively due to far-UV wavelengths transmissible through UV-R-250 and UV-R-280 interference filters . The main mutagenic component of fluorescent light (254 nm) were almost 10(4)-fold more mutagenic than near-UV wavelengths (365 nm) . All light sources exhibited some residual mutagenicity even following filtration through various cloths . On the other hand, appropriate glass or plastic covers consistently prevented mutagenic effects . This emphasizes the urgent need for a compulsory shielding of halogen and fluorescent lamps in order to prevent unnecessary exposures to genotoxic and potentially carcinogenic UV radiations.

Toxicol Lett, 1990 Dec, 54(2-3), 309 - 15
Prochloraz as potent inhibitor of benzo{a}pyrene metabolism and mutagenic activity in rat liver fractions; Antignac E et al.; We have determined how prochloraz, an imidazole antifungal agent, affects the metabolism of benzo{a}-pyrene by hepatic microsomes from 3-methylcholanthrene treated male rats . The prochloraz-like 7,8-benzoflavone was a potent inhibitor of total benzo{a}pyrene metabolism while miconazole was a weak inhibitor . The proportion of benzo{a}pyrene dihydrodiols formed was decreased whereas phenols were increased by the in vitro addition of prochloraz . Furthermore, a good correlation was obtained between the effects of prochloraz on the microsomal formation of benzo{a}pyrene metabolites and on the mutagenic activity of benzo{a}pyrene in the Salmonella typhimurium test.

Mutat Res, 1990 Dec, 242(4), 337 - 43
Mutagenicity of dibenz{a,c}anthracene and its derivatives in Salmonella typhimurium TA100; Kumar S et al.; The mutagenic activities of dibenz{a,c}anthracene (DB{a,c}A), and its 11 derivatives, including 3 diols, 6 phenols and 2 oxepines, were studied in the TA100 strain of Salmonella typhimurium at doses varying from 0 to 20 micrograms/plate in the presence of a rat-liver S9 (9000 x g) preparation . Among the diols of DB{a,c}A tested DB{a,c}A-10,11-diol was the most mutagenic compound . However, it was consistently less mutagenic than the parent hydrocarbon . Oxepine-1 and oxepine-2 which are believed to be the photoisomerized products of DB{a,c}A-1,2 oxide and DB{a,c}A-3,4-oxide, respectively, were also less mutagenic than DB{a,c}A . In contrast to these results, 4-hydroxyDB{a,c}A was almost twice as active as DB{a,c}A, and 2-hydroxy- and 3-hydroxyDB{a,c}A were even more (4-6-fold) mutagenic than DB{a,c}A . The remaining phenols were relatively inactive or weakly active in this mutagenicity assay . These results provide initial evidence that the bay-region theory may not be applicable to the mutagenesis of DB{a,c}A, and that the angular ring substituted phenols of DB{a,c}A may be involved in the metabolic activation of this highly mutagenic hydrocarbon.

J Bacteriol, 1990 Dec, 172(12), 7200 - 10
Role of purine biosynthetic intermediates in response to folate stress in Escherichia coli; Rohlman CE et al.; Folic acid plays a central role in anabolic metabolism by supplying single-carbon units at varied levels of oxidation for both nucleotide and amino acid biosyntheses . It has been proposed that 5-amino-4-imidazole carboxamide riboside 5'-triphosphate (ZTP), an intermediate in de novo purine biosynthesis, serves as a signal of cellular folate stress and mediates a physiologically beneficial response to folate stress in Salmonella typhimurium (B . R . Bochner, and B . N . Ames, Cell 29:929-937, 1982) . We examined the physiological response of Escherichia coli to folate stress induced by the drugs psicofuranine, trimethoprim, and sodium sulfathiazole or by p-aminobenzoic acid (pABA) starvation . Analysis of nucleotide pools showed that psicofuranine or trimethoprim treatment of a prototrophic strain or growth of a pABA auxotroph on limiting pABA induced the production of the nucleotide ZTP, as previously observed in S . typhimurium by Bochner and Ames . Accumulation of ZTP and its precursor 5-amino-4-imidazole carboxamide riboside 5'-monophosphate (ZMP) did not correlate well with folate stress in E . coli, as measured by determination of the folate/protein ratios of extracts of treated cells . Treatment of cells with psicofuranine caused a marked accumulation of 5-amino-4-imidazole carboxamide ribonucleotides (Z-ribonucleotides) but a statistically insignificant drop in the folate/protein ratio of cell extracts . Sodium sulfathiazole treatment at a drug concentration that led to a threefold drop in the growth rate and in the folate/protein ratio of treated cells led to little accumulation of Z-ribonucleotides in E . coli A purF his+ strain which produces ZTP and ZMP when treated with trimethoprim was constructed . In this strain, histidine represses the synthesis of both ZMP and ZTP . Treatment of cells of this strain with trimethoprim resulted in a decrease in the folate/protein ratio of cell extracts, but a blockade of Z-ribonucleotide accumulation did not affect the extent of folate depletion seen in treated cells and had only a small effect on the resistance of this strain to growth inhibition by trimethoprim . The patterns of protein expression induced by treatment of this strain with trimethoprim or psicofuranine were examined by two-dimensional electrophoretic resolution of the total cellular proteins . No differences in protein expression were seen when the treatment were performed in media containing or lacking histidine . These studies failed to provide evidence in E . coli for a folate stress regulon controlled by ZTP.

J Bacteriol, 1990 Dec, 172(12), 7071 - 84
Cloning and sequence of the Salmonella typhimurium hemL gene and identification of the missing enzyme in hemL mutants as glutamate-1-semialdehyde aminotransferase; Elliott T et al.; Salmonella typhimurium forms the heme precursor delta-aminolevulinic acid (ALA) exclusively from glutamate via the five-carbon pathway, which also occurs in plants and some bacteria including Escherichia coli, rather than by ALA synthase-catalyzed condensation of glycine and succinyl-coenzyme A, which occurs in yeasts, fungi, animal cells, and some bacteria including Bradyrhizobium japonicum and Rhodobacter capsulatus . ALA-auxotrophic hemL mutant S . typhimurium cells are deficient in glutamate-1-semialdehyde (GSA) aminotransferase, the enzyme that catalyzes the last step of ALA synthesis via the five-carbon pathway . hemL cells transformed with a plasmid containing the S . typhimurium hemL gene did not require ALA for growth and had GSA aminotransferase activity . Growth in the presence of ALA did not appreciably affect the level of extractable GSA aminotransferase activity in wild-type cells or in hemL cells transformed with the hemL plasmid . These results indicate that GSA aminotransferase activity is required for in vivo ALA biosynthesis from glutamate . In contrast, extracts of both wild-type and hemL cells had gamma,delta-dioxovalerate aminotransferase activity, which indicates that this reaction is not catalyzed by GSA aminotransferase and that the enzyme is not encoded by the hemL gene . The S . typhimurium hemL gene was sequenced and determined to contain an open reading frame of 426 codons encoding a 45.3-kDa polypeptide . The sequence of the hemL gene bears no recognizable similarity to the hemA gene of S . typhimurium or E . coli, which encodes glutamyl-tRNA reductase, or to the hemA genes of B . japonicum or R . capsulatus, which encode ALA synthase . The predicted hemL gene product does show greater than 50% identity to barley GSA aminotransferase over its entire length . Sequence similarity to other aminotransferases was also detected.

J Bacteriol, 1990 Dec, 172(12), 7043 - 8
Cloning of the Klebsiella aerogenes nac gene, which encodes a factor required for nitrogen regulation of the histidine utilization (hut) operons in Salmonella typhimurium; Best EA et al.; The nac (nitrogen assimilation control) gene from Klebsiella aerogenes, cloned in a low-copy-number cloning vector, restored the ability of K . aerogenes nac mutants to activate histidase and repress glutamate dehydrogenase formation in response to nitrogen limitation and to limit the maximum expression of the nac promoter . When present in Salmonella typhimurium, the K . aerogenes nac gene allowed the hut genes to be activated during nitrogen-limited growth . Thus, the nac gene encodes a cytoplasmic factor required for activation of hut expression in S . typhimurium during nitrogen-limited growth.

J Bacteriol, 1990 Dec, 172(12), 6919 - 29
In vitro interactions of CysB protein with the cysK and cysJIH promoter regions of Salmonella typhimurium; Monroe RS et al.; The cysteine regulons of Salmonella typhimurium and Escherichia coli are positively regulated by CysB protein and either O-acetyl-L-serine or N-acetyl-L-serine, both of which act as inducers . Gel mobility shift assays and DNase I footprinting experiments showed that CysB protein binds to the S . typhimurium cysK promoter at two sites, one, designated CBS-K1, at positions -78 to -39 relative to the major transcription start site, and the other, designated CBS-K2, at positions -115 to -79 . The S . typhimurium cysJIH promoter was found to contain a single binding site, designated CBS-JH, at positions -76 to -35 . Acetyl-L-serine stimulated binding to CBS-K1 and CBS-J and inhibited binding to CBS-K2 . In the absence of acetyl-L-serine, CysB protein bound to both CBS-K1 and CBS-K2 and gave a complex that migrated more slowly during gel electrophoresis than did that formed in the presence of acetyl-L-serine, in which case CysB protein bound only to CBS-K1 . Complexes formed with DNA containing the two binding sites either at the middle or at one end of the fragment migrated differently, suggesting that DNA was bent in the slow complex formed in the absence of acetyl-L-serine and that DNA in the fast complex was less bent or not bent at all . An analysis of upstream deletions of the cysK promoter showed that only CBS-K1 is required for in vivo promoter activity . CBS-J is analogous in position to CBS-K1 and is probably also required for activity of the cysJIH promoter . CBS-K2 has no known function but may help sequester CysB protein at the cysK promoter.

J Bacteriol, 1990 Dec, 172(12), 6727 - 35
Cloning and sequencing of the sacA gene: characterization of a sucrase from Zymomonas mobilis; Gunasekaran P et al.; The Zymomonas mobilis gene (sacA) encoding a protein with sucrase activity has been cloned in Escherichia coli and its nucleotide sequence has been determined . Potential ribosome-binding site and promoter sequences were identified in the region upstream of the gene which were homologous to E . coli and Z . mobilis consensus sequences . Extracts from E . coli cells, containing the sacA gene, displayed a sucrose-hydrolyzing activity . However, no transfructosylation activity (exchange reaction or levan formation) could be detected . This sucrase activity was different from that observed with the purified extracellular protein B46 from Z . mobilis . These two proteins showed different electrophoretic mobilities and molecular masses and shared no immunological similarity . Thus, the product of sacA (a polypeptide of 58.4-kDa molecular mass) is a new sucrase from Z . mobilis . The amino acid sequence, deduced from the nucleotide sequence of sacA, showed strong homologies with the sucrases from Bacillus subtilis, Salmonella typhimurium, and Vibrio alginolyticus.

J Bacteriol, 1990 Dec, 172(12), 6721 - 6
Overproduction of release factor reduces spontaneous frameshifting and frameshift suppression by mutant elongation factor Tu; Aulin MR et al.; Mutant forms of elongation factor Tu encoded by tufA8 and tufB103 in Salmonella typhimurium cause suppression of some but not all frameshift mutations . All of the suppressed mutations in S . typhimurium have frameshift windows ending in the termination codon UGA . Because both tufA8 and tufB103 are moderately efficient UGA suppressors, we asked whether the efficiency of frameshifting is influenced by the level of misreading at UGA . We introduced plasmids synthesizing either one of the release factors into strains in which the tuf mutations suppress a test frameshift mutation . We found that overproduction of release factor 2 (which catalyzes release at UGA and UAA) reduced frameshifting promoted by the tuf mutations at all sites tested . However, at one of these sites, trpE91, overproduction of release factor 1 also reduced suppression . The spontaneous level of frameshift "leakiness" at three sites in trpE, each terminating in UGA, was reduced in strains carrying the release factor 2 plasmid . We conclude that both spontaneous and suppressor-enhanced reading-frame shifts are influenced by the activity of peptide chain release factors . However, the data suggest that the effect of release factor on frameshifting does not necessarily depend on the presence of the normal triplet termination signal.

Infect Immun, 1990 Dec, 58(12), 3899 - 902
Polymorphic expression of defensins in neutrophils from outbred rats; Eisenhauer P et al.; We isolated and characterized a rat neutrophil defensin, RatNP-2, that differs from the previously described defensin RatNP-1 by containing Ser-7 in place of Arg-7 . Although the resulting charge difference rendered RatNP-2 easily distinguishable from RatNP-1 on polyacrylamide gel electrophoresis gels, the two defensins exhibited very similar antimicrobial efficacies against Salmonella typhimurium, Staphylococcus aureus, and Candida albicans . The polymorphonuclear leukocytes of Sprague-Dawley rats obtained from one of two breeders also showed a marked polymorphism for defensin RatNP-4 . This defensin was absent in two of seven animals and present in 1x or 2x relative amounts in the others . These observations indicate that a striking degree of defensin polymorphism exists in the polymorphonuclear leukocytes of outbred rodents.

J Infect Dis, 1990 Dec, 162(6), 1397 - 400
Occurrence of secondary attenuating mutations in avirulent Salmonella typhimurium vaccine strains; Lockman HA et al.; The attenuating delta aroA554 mutation in Salmonella typhimurium strain SL3261 was complemented in vitro by selecting for AroA+ recombinant DNA clones . SL3261 containing cloned aroA+ genes did not require exogenous phenylalanine, tryptophan, tryosine, p-aminobenzoic acid, or dihydroxybenzoic acid for growth in defined media . Cloned aroA+ genes did not restore wild-type virulence to SL3261, however, in a murine typhoid model . The delta aroA554 mutation was transduced into S . typhimurium strain SR-11, a mouse-virulent strain recently passaged in mice . The SR-11 delta aroA554 mutant was highly attenuated for mice challenged parenterally . The same cloned aroA+ genes isolated in SL3261 restored the virulence of the SR-11 delta aroA554 mutant to that of wild-type SR-11 . These results suggest that while the delta aroA554 allele remains effective in reducing S . typhimurium virulence, laboratory passage of attenuated vaccine strains may lead to the accumulation of additional attenuating defects.

Proc Natl Acad Sci U S A, 1990 Dec, 87(24), 9823 - 7
Method for identifying microbial antigens that stimulate specific lymphocyte responses: application to Salmonella; Warren RL et al.; Vaccine development and understanding of cellular immune stimulatory mechanisms have been impeded by the paucity of data on microbial antigens that stimulate protective immunity . We describe here a general method for identifying and isolating peptide antigens that specifically stimulate sensitized lymphocytes . First, Salmonella typhimurium C5 genomic DNA fragments were subcloned into Escherichia coli by use of the lambda gt11 expression vector . Next, antigens expressed by recombinant phage from this genomic library were tested for their capacity to stimulate proliferative responses in pooled lymphocytes obtained from BALB/c mice infected 14 days earlier with S . typhimurium . Of 2000 recombinant phages tested, 5 stimulated a polypeptide-antigen-specific proliferative response . Physical analyses of these 5 recombinant phages revealed cloned inserts of 0.5-2.4 kilobase pairs representing nonoverlapping regions of the C5 chromosome . Four of the five insert DNAs hybridized at high stringency to both S . typhimurium and Salmonella typhi total chromosomal DNA, suggesting that these pathogens of different host specificity share several antigenic determinants . Use of sensitized primary polyclonal lymphocytes provides a rapid and simple method for screening recombinant DNA libraries for clones that stimulate specific immune responses and avoids the use of cloned lymphocyte cell lines . This approach should be generally applicable to similar studies in different hosts of many other microbial pathogens.

Zentralbl Hyg Umweltmed, 1990 Dec, 190(5-6), 536 - 46
{An automated in vitro toxicity test of 25 chemicals}; Jakob R et al.; A computer controlled bench-top analyser was used to establish an automated in vitro-cytotoxicity test . It is based on the continuous monitoring of growth of Salmonella typhimurium TA 98 and TA 100 (strains that are also employed in the classical Ames test (1) for mutagenicity screening) under the influence of the toxic compounds . With this method we can quantify general cytotoxicity and in addition, some questions concerning the mechanism of the toxic influence on the test organisms can be answered . Its simplicity and reliability as well as the good correlation with in vivo data make the new test system suitable for pre-screening the toxicity of a large number of compounds within short time.

J Anim Sci, 1990 Dec, 68(12), 4303 - 9
Effect of vitamin E and selenium supplementation on some immune parameters following vaccination against brucellosis in cattle; Nemec M et al.; Twenty-four 7-mo-old beef heifers (Charolais Simmental cross), weighing 213 kg, were used to determine the effect of vitamin E (VitE) and(or) selenium (Se) supplementation on the humoral response to a standard dose of Brucella abortus strain 19 vaccine and on the levels of naturally occurring immunoglobulins (Ig) to several antigens . The treatments were as follows: Group 1, no supplement; Group 2, supplementation with 6 g of elemental Se; Group 3, supplementation with 1,400 IU/d of VitE; and Group 4, Se and VitE supplements combined . There were no significant differences in anti-B . abortus IgG1, IgG2, or IgM antibody levels due to Se, VitE or Se/VitE treatments; the concentrations of IgA antibody were too low to be measured with the ELISA test used . Statistical analysis revealed that the levels of total and IgM natural antibody to Salmonella typhimurium were higher in Group 3 . Perhaps VitE supplementation given in conjunction with B . abortus vaccine enhanced the production of antibody to S . typhimurium in several animals whose humoral system had been activated by previous exposure to this organism.

Jpn J Cancer Res, 1990 Dec, 81(12), 1253 - 8
Species difference among experimental rodents in the activity and induction of cytochrome P-450 isozymes for mutagenic activation of carcinogenic aromatic amines; Degawa M et al.; The expressions of hepatic microsomal cytochrome P-450 isozymes in male rats, mice, hamsters and guinea pigs were studied comparatively with or without an ip injection of a cytochrome P-450 inducer . The activity and quantity of microsomal cytochrome P-450 isozymes were determined respectively by a bacterial mutation assay with Salmonella typhimurium TA98 and immunochemical assays using monoclonal antibodies against rat cytochrome P-450 isozymes . 3-Methoxy-4-aminoazobenzene (3-MeO-AAB), 2-amino-3-methyl-9H-pyrido{2,3-b}indole acetate (MeA alpha C) and 3-methylcholanthrene were used as cytochrome P-450 inducers, and 7 carcinogenic aromatic amines including 3-MeO-AAB and MeA alpha C were used as substrates for the mutation assay . By means of these assays, we examined the species differences among rodents in the activity and induction rate of hepatic cytochrome P-450 isozymes responsible for the mutagenic activation of carcinogenic aromatic amines.

J Med Microbiol, 1990 Dec, 33(4), 235 - 8
Mechanisms of zidovudine resistance in bacteria; Lewin CS et al.; Unlike their parent strains, zidovudine-resistant derivatives of Escherichia coli KL16 and Salmonella typhimurium NCTC 5710 were found to be incapable of incorporating radiolabelled thymidine into their chromosomal DNA . Since incorporation was still prevented in the presence of EDTA, resistance to zidovudine was not associated with a permeability barrier, but appeared to result from the loss of thymidine kinase activity, required for the phosphorylation of zidovudine . Pseudomonas aeruginosa, which is intrinsically zidovudine-resistant, was also shown to be incapable of incorporating thymidine into its DNA, but Staphylococcus epidermidis SK360 and Staph . aureus E3T, which are also intrinsically zidovudine-resistant, possessed thymidine kinase activity . This suggests that two distinct mechanisms of resistance to zidovudine exist in bacteria . Zidovudine resistance did not appear to confer resistance to other antibacterial agents.

J Bacteriol, 1990 Dec, 172(12), 6661 - 8
Purification and characterization of the Myxococcus xanthus FrzE protein shows that it has autophosphorylation activity; McCleary WR et al.; Myxococcus xanthus exhibits multicellular interactions during vegetative growth and fruiting body formation . Gliding motility is needed for these interactions . The frizzy (frz) genes are required to control directed motility . FrzE is homologous to both CheA and CheY from Salmonella typhimurium . We used polyclonal antiserum raised against a fusion protein to detect FrzE in M . xanthus extracts by Western immunoblot analysis . FrzE was clearly present during vegetative growth and at much lower levels during development . A recombinant FrzE protein was overproduced in Escherichia coli, purified from inclusion bodies, and renatured . FrzE was autophosphorylated when it was incubated in the presence of {gamma-32P}ATP and MnCl2 . Chemical analyses of the phosphorylated FrzE protein indicated that it contained an acylphosphate; probably phosphoaspartate . FrzE was phosphorylated in an intramolecular reaction . Based on these observations, we propose a model of the mechanism of FrzE phosphorylation in which autophosphorylation initially occurs at a conserved histidine residue within the "CheA" domain and then, via an intramolecular transphosphorylation, is transferred to a conserved aspartate residue within the "CheY" domain.

Mol Microbiol, 1990 Dec, 4(12), 2187 - 92
Identification of hypoxanthine and guanine as the co-repressors for the purine regulon genes of Escherichia coli; Meng LM et al.; Addition of purine compounds to the growth medium of Escherichia coli and Salmonella typhimurium causes repressed synthesis of the purine biosynthetic enzymes . The repression is mediated through a regulatory protein, PurR . To identify the co-repressor(s) of PurR, two approaches were used: (i) mutations were introduced into purine salvage genes and the effects of different purines on pur gene expression were determined; (ii) purine compounds which dictate the binding of the PurR protein to its operator DNA were resolved by gel retardation . Both the in vivo and the in vitro data indicated that guanine and hypoxanthine are co-repressors . The toxic purine analogues 6-mercaptopurine and 6-thioguanine also activated the binding of PurR to its operator DNA.

Mol Microbiol, 1990 Dec, 4(12), 2111 - 8
Generation of a cytotoxic T-lymphocyte response using a Salmonella antigen-delivery system; Flynn JL et al.; We have constructed a general-use vector for the cloning and stable expression of foreign genes in the chromosome of attenuated Salmonella typhimurium . Using this chromosomal expression vector (CEV), we expressed the circumsporozoite (CS) gene of the mouse malaria Plasmodium yoelii in an aroA S . typhimurium strain . Mice immunized with CS-expressing Salmonella recombinants mount a CS-specific cytotoxic T-lymphocyte (CTL) response . This is the first demonstration that attenuated Salmonella can elicit a specific CTL response to a foreign protein in mice . The ability to easily and stably express foreign genes from the Salmonella chromosome and the generation of specific CTL greatly expands the potential of Salmonella as an antigen-delivery system.

Poult Sci, 1990 Dec, 69(12), 2248 - 51
Combined halogen disinfectants in poultry processing; Williams DE et al.; Three organic N-halamine compounds (combined halogen disinfectants) were compared with free chlorine (as calcium hypochlorite) as bactericides against Salmonella typhimurium and unidentified normal poultry bacterial flora under controlled conditions of pH, temperature, and halogen demand similar to those encountered in poultry processing . Two of the compounds (3-chloro-4,4-dimethyl-2-oxazolidinone and 1,3-dichloro-4,4,5,5-tetramethyl-2-imidazolidinone) at a concentration of 50 mg/L were found to cause a 99.9999% decline in viable organisms in less than 1 min at 48 C, whereas a third compound (1-bromo-3-chloro-4,4,5,5-tetramethyl-2-imidazolidinone) was found to be less suitable (5.6 min to 99.9999% decline under the same conditions).

Poult Sci, 1990 Dec, 69(12), 2244 - 7
Effects of D-mannose on incidence and levels of salmonellae in ceca and carcass samples of market age broilers; Izat AL et al.; Two similar trials were conducted to evaluate the effects of 2.5% d-mannose (DM) in the drinking water of broilers for the first 10 days on incidence and levels of salmonellae in the ceca and on the carcass at market age . Controls received drinking water with no DM . Birds were reared on used litter in floor pens and were inoculated via the drinking water with 10(8) cfu/mL Salmonella typhimurium (ATCC 14028) on Day 3 . At 49 days, 60 birds per treatment were processed and the ceca contents and prechill carcass were evaluated for salmonellae incidence by the most probable number (MPN) method . Results were inconclusive: level of salmonellae in the ceca contents and carcass rinse was significantly lower in control samples than in DM samples in one of the two trials; the reverse was true in the other trial.

Poult Sci, 1990 Dec, 69(12), 2128 - 33
Effect of litter condition on microbiological quality of freshly killed and processed broilers; Reiber MA et al.; Two similar trials were conducted to evaluate the effects of litter condition on microbiological quality of freshly killed (feathers intact) and processed broilers . Commercial broilers were reared to 49 days of age on new or previously used litter . Birds in half of the replicate pens were inoculated with Salmonella typhimurium via the drinking water on Days 2, 7, 14, and 21 . Broilers were sampled at the following processing locations: postkill, postpick, prechill, and postchill . Postchill carcasses from birds raised on previously used litter did not have significantly different aerobic plate counts, levels of coliforms, or numbers of salmonellae as compared with carcasses from birds raised on new litter . Live bird inoculation did significantly increase levels of salmonellae on the fully processed carcass.

Appl Environ Microbiol, 1990 Dec, 56(12), 3741 - 7
Remnants of an ancient pathway to L-phenylalanine and L-tyrosine in enteric bacteria: evolutionary implications and biotechnological impact; Bonner CA et al.; The pathway construction for biosynthesis of aromatic amino acids in Escherichia coli is atypical of the phylogenetic subdivision of gram-negative bacteria to which it belongs (R . A . Jensen, Mol . Biol . Evol . 2:92-108, 1985) . Related organisms possess second pathways to phenylalanine and tyrosine which depend upon the expression of a monofunctional chorismate mutase (CM-F) and cyclohexadienyl dehydratase (CDT) . Some enteric bacteria, unlike E . coli, possess either CM-F or CDT . These essentially cryptic remnants of an ancestral pathway can be a latent source of biochemical potential under certain conditions . As one example of advantageous biochemical potential, the presence of CM-F in Salmonella typhimurium increases the capacity for prephenate accumulation in a tyrA auxotroph . We report the finding that a significant fraction of the latter prephenate is transaminated to L-arogenate . The tyrA19 mutant is now the organism of choice for isolation of L-arogenate, uncomplicated by the presence of other cyclohexadienyl products coaccumulated by a Neurospora crassa mutant that had previously served as the prime biological source of L-arogenate . Prephenate aminotransferase activity was not conferred by a discrete enzyme, but rather was found to be synonymous with the combined activities of aspartate aminotransferase (aspC), aromatic aminotransferase (tyrB), and branched-chain aminotransferase (ilvE) . This conclusion was confirmed by results obtained with combinations of aspC-, tyrB-, and ilvE-deficient mutations in E . coli . An example of disadvantageous biochemical potential is the presence of a cryptic CDT in Klebsiella pneumoniae, where a mutant carrying multiple enzyme blocks is the standard organism used for accumulation and isolation of chorismate.(ABSTRACT TRUNCATED AT 250 WORDS)

Mol Microbiol, 1990 Dec, 4(12), 2119 - 26
Characterization of the type 1 fimbrial subunit gene (fimA) of Serratia marcescens; Nichols WA et al.; The nucleotide sequence of a DNA fragment that contains the fimA gene, encoding the major fimbrial subunit, of Serratia marcescens IA506 and associated flanking sequences has been elucidated . In addition, the origin of transcription has been identified and is located 120 base pairs upstream of the fimA initiation codon . The predicted amino acid sequence of the FimA polypeptide exhibits some degree of sequence homology with the fimbrial subunits encoded by the fimA determinants of Klebsiella pneumoniae, Salmonella typhimurium, and Escherichia coli and also to Smf2, the major structural component of mannose-resistant (MR) fimbriae of S . marcescens . The Serratia adhesin that facilitates haemagglutination mediated by type 1 fimbriae is less susceptible to inhibition by D-mannose than has been observed to be the case in other type 1 fimbrial adhesins . The molecule conferring this adherence specificity has been shown to be distinct from the fimA gene product and, therefore, is analogous to the fimbrial systems reported in other species.

Eur J Immunol, 1990 Dec, 20(12), 2763 - 8
Efficient recognition by rat T cell clones of an epitope of mycobacterial hsp 65 inserted in Escherichia coli outer membrane protein PhoE; Hogervorst EJ et al.; PhoE is a pore-forming protein, abundantly expressed in the Escherichia coli outer membrane . Previous investigations have shown the possibility of inserting antigenic determinants in cell surface-exposed regions of PhoE by recombinant DNA techniques without disturbing the biogenesis and the functioning of the protein . This method proved to be successful for foot-and-mouth disease virus B cell determinants . We have now shown for the first time that PhoE can also be used as a carrier molecule for T cell epitopes . A well-characterized T cell epitope (180-188) of the 65-kDa heat-shock protein (hsp 65) of Mycobacterium tuberculosis was expressed in PhoE and tested for recognition by specific T cell clones . Specific and efficient T cell proliferation was found after stimulation with this protein construct in vitro . Interestingly, paraformaldehyde fixation of antigen-presenting cells did not abrogate T cell recognition . Thus, in contrast to hsp 65 itself, recognition of epitope 180-188 in the context of PhoE appeared to be independent of antigen-processing events . At the level of polyclonal T cell responses the epitope in the context of PhoE is recognized more efficiently than 180-188 as synthetic peptide or in the context of the hsp 65 molecule itself . These findings indicate that PhoE may serve as attractive vaccine carrier not only for B, but also for T cell epitopes . Furthermore, the possibility for expression of PhoE constructs in attenuated Salmonella typhimurium strains offers the exciting prospect of new types of live oral vaccines expressing selected combinations of B and T cell epitopes.

J Bacteriol, 1990 Dec, 172(12), 7151 - 6
Sequence of the pckA gene of Escherichia coli K-12: relevance to genetic and allosteric regulation and homology of E . coli phosphoenolpyruvate carboxykinase with the enzymes from Trypanosoma brucei and Saccharomyces cerevisiae; Medina V et al.; The sequence of the pckA gene coding for phosphoenolpyruvate carboxykinase in Escherichia coli K-12 and previous molecular weight determinations indicate that this allosteric enzyme is a monomer of Mr 51,316 . The protein is homologous to ATP-dependent phosphoenolpyruvate carboxykinases from Trypanosoma brucei and Saccharomyces cerevisiae . A potential ATP binding site was conserved in all three sequences . A potential binding site for the allosteric activator, calcium, identified in the E . coli enzyme, was only partially conserved in T . brucei and S . cerevisiae, consistent with the observation that the enzymes from the latter organisms were not activated by calcium . The published sequence of the ompR and envZ genes from Salmonella typhimurium is followed by a partial sequence that is highly homologous to pckA from E . coli . The order of these genes and the direction of transcription of the presumptive S . typhimurium pckA gene are the same as those in E . coli . The potential calcium binding site of the E . coli enzyme is conserved in the partial predicted sequence of the S . typhimurium phosphoenolpyruvate carboxykinase, consistent with the observation that calcium activation of the S . typhimurium phosphoenolpyruvate carboxykinase is very similar to that observed for the E . coli enzyme . A pckA mRNA transcript was observed in stationary-phase cells but not in logarithmically growing cells . The mRNA start site was mapped relative to the sequence of the pckA structural gene.

Nucleic Acids Res, 1990 Nov 25, 18(22), 6503 - 8
A novel repeated DNA sequence located in the intergenic regions of bacterial chromosomes; Sharples GJ et al.; We report the discovery of a novel group of highly conserved DNA sequences located within the intergenic regions of the chromosomes of Escherichia coli, Salmonella typhimurium and other bacteria . These intergenic repeat units (IRUs) are 124-127 nucleotides long and have the potential to form stable stem-loop structures . The location of these sequences within the intergenic regions is variable with respect to known or putative signals for transcription and translation of the flanking genes . Some of the IRU sequences are transcribed, others are probably not . The structure and possible functions of these sequences are discussed in relation to palindromic units and other repeated DNA sequences in bacteria.

Biochemistry, 1990 Nov 20, 29(46), 10480 - 7
Kinetic mechanism of orotate phosphoribosyltransferase from Salmonella typhimurium; Bhatia MB et al.; The chemical mechanism of the phosphoribosyltransferases (PRTases), although largely unknown, may proceed either via a concerted direct-transfer mechanism or with a two-step mechanism involving a carboxonium-like intermediate . To study this question, we have cloned the Salmonella typhimurium pyrE gene, coding for the enzyme orotate phosphoribosyltransferase (EC 2.2.4.10, OPRTase), and developed a bacterial strain that overproduces the enzyme, which we have purified to homogeneity . Initial velocity and product inhibition studies indicated that S . typhimurium OPRTase follows a random sequential kinetic mechanism . This result was further confirmed by equilibrium isotope exchange studies on two substrate-product pairs, PRPP-PPi and OMP-orotate . In addition, the rates of the individual equilibrium isotope exchanges allowed us to conclude that PPi release and PRPP release were the rate-determining steps in the forward and reverse reactions, respectively . Although partial reactions between the two substrate-product pairs, PRPP-PPi and OMP-orotate, were observed, further studies revealed that these exchanges were a result of contaminations . Our results are significant in that S . typhimurium OPRTase, like most PRTases but in contrast to its yeast homologue, follows sequential kinetics . The artifactual partial isotope exchanges found in this work may have implications for similar prior work on the yeast enzyme . In view of the careful isotope effect studies of Parsons and co-workers {Goitein, R.K., Chelsky, D., & Parsons, S.M . (1978) J . Biol . Chem . 253, 2963-2971} and the results obtained by us, we propose that PRTases may involve a direct-transfer mechanism but with low bond order to the leaving pyrophosphate moiety and attacking base.

J Biol Chem, 1990 Nov 15, 265(32), 19892 - 7
Purification and characterization of a methionine aminopeptidase from Saccharomyces cerevisiae; Chang YH et al.; Methionine aminopeptidase (MAP), which catalyzes the removal of NH2-terminal methionine from proteins, was isolated from Saccharomyces cerevisiae . The enzyme was purified 472-fold to apparent homogeneity . The Mr of the native enzyme was estimated to be 36,000 +/- 5,000 by gel filtration chromatography, and the Mr of the denatured protein was estimated to be 34,000 +/- 2,000 by sodium dodecyl sulfate-polyacrylamide gel electrophoresis . The enzyme has a pH optimum near 7.0, and its pI is 7.8 as determined by chromatofocusing on Mono P . The enzyme was inactivated by metalloprotease inhibitors (EDTA, o-phenanthroline and nitrilotriacetic acid), sulfhydryl-modifying reagents (HgCl2 and p-hydroxymercuribenzoic acid), and Zn2+ . Yeast MAP failed to cleave methionine p-nitroanilide . Among 11 Xaa-Ala-Ser analogues (Xaa = Ala, Asp, Gln, Glu, Ile, Leu, Lys, Met, Phe, Pro, and Ser), MAP cleaved only Met-Ala-Ser . MAP also cleaved methionine from other tripeptides whose penultimate amino acid residue is relatively small and/or uncharged (e.g . Pro, Gly, Val, Thr, or Ser) but not when bulky and/or charged (Arg . His, Leu, Met, or Tyr) . Yeast MAP displayed similar substrate specificities compared with those of Escherichia coli (Ben-Bassat, A., Bauer, K., Chang, S.Y., Myambo, K., Boosman, A., and Chang, S . (1987) J . Bacteriol . 169, 751-757) and Salmonella typhimurium MAP (Miller, C., Strauch, K . L., Kukral, A . M., Miller, J . L., Wingfield, P . T., Mazzei, G . J., Werlen, R . C., Garber, P., and Movva, N . R . (1987) Proc . Natl, Acad . Sci . U.S.A . 84, 2718-2722) . In general, the in vitro specificity of yeast MAP is consistent with the specificity observed in previous in vivo studies in yeast (reviewed in Arfin, S . M., and Bradshaw, R . A . (1988) Biochemistry 27, 7979-7984).

J Biol Chem, 1990 Nov 15, 265(32), 19535 - 42
The nucleotide-binding site of HisP, a membrane protein of the histidine permease . Identification of amino acid residues photoaffinity labeled by 8-azido-ATP; Mimura CS et al.; The periplasmic histidine transport system (permease) of Escherichia coli and Salmonella typhimurium is composed of a soluble, histidine-binding receptor located in the periplasm and a complex of three membrane-bound proteins of which one, HisP, was shown previously to bind ATP . These permeases are energized by ATP . HisP is a member of a family of membrane transport proteins which is conserved in all periplasmic permeases and is presumed to be involved in coupling the energy of ATP to periplasmic transport . In this paper the nature of the ATP-binding site of HisP has been explored by identification of some of the residues that come into contact with ATP . HisP was derivatized with 8-azido-ATP (N3ATP) . Both the underivatized and the derivatized forms of HisP were solubilized, purified, and digested with trypsin . The resulting tryptic peptides were resolved by high pressure liquid chromatography, and peptides modified by N3ATP were isolated and sequenced . Two peptides, X and Z, spanning amino acid residues 16-23 and 31-45, were found to contain sites of N3ATP attachment at His19 and Ser41, respectively . Both peptides are close to the amino-terminal end of HisP; peptide Z is located in one of the well conserved regions comprising the nucleotide-binding consensus motifs of the energy-coupling components of these permeases . These consensus motifs are found in many purine nucleotide-binding proteins . The relationship between the location of these residues and the overall structure of the ATP-binding site is discussed.

Biochemistry, 1990 Nov 13, 29(45), 10342 - 50
Comparison of the DNA-alkylating properties and mutagenic responses of a series of S-(2-haloethyl)-substituted cysteine and glutathione derivatives; Humphreys WG et al.; The mutagenicity of 1,2-dibromoethane is highly dependent upon its conjugation to glutathione by the enzyme glutathione S-transferase . The conjugates thus formed can react with DNA and yield almost exclusively N7-guanyl adducts . We have synthesized the S-haloethyl conjugates of cysteine and glutathione, as well as selected methyl ester and N-acetyl derivatives, and compared them for ability to produce N7-guanyl adducts with calf thymus DNA . The cysteine compounds were found to be more reactive toward calf thymus DNA and yielded higher adduct levels than did the glutathione compounds . Adduct levels tended to be suppressed when there was a net charge on the compound and were not affected by substitution of bromine for chlorine, as expected for a mechanism known to involve an intermediate episulfonium ion . Sequence-selective alkylation of fragments of pBR322 DNA was investigated . The compounds produced qualitatively similar patterns of alkylation, with higher levels of alkylation at runs of guanines . The compounds were also tested for their ability to act as direct mutagens in Salmonella typhimurium TA98 and TA100 . None of the compounds caused mutations in the TA98 frameshift mutagenesis assay . In the strain TA100, where mutation of a specific guanine by base-pair substitution produces reversion, all compounds were found to produce mutations, but the levels of mutagenicity did not correlate at all with the levels of DNA alkylation . The ratio of mutations to adducts varied at least 14-fold among the various N7-guanyl adducts examined.(ABSTRACT TRUNCATED AT 250 WORDS)

Cancer Lett, 1990 Nov 5, 54(3), 163 - 9
Glucose alters rat liver S9-mediated mutagenesis, metabolism and DNA-binding of aflatoxin B1; Teel RW et al.; The administration of 30% glucose in drinking water to rats for 48 h caused a significant increase in the hepatic S9-mediated mutagenicity of aflatoxin B1, in Salmonella typhimurium TA100 and in the binding of alfatoxin B1, to calf thymus DNA in vitro . These effects correlated with a reduction in the metabolism and detoxification of aflatoxin B1, by S9 from glucose-treated rats and suggest that the oral intake of sugar may affect the hepatocarcinogenicity of aflatoxin B1.

Mutat Res, 1990 Nov, 242(3), 209 - 17
Study on mutagenicity and antimutagenicity of BHT and its derivatives in a bacterial assay; Yoshida Y; The mutagenicity of butylated hydroxytoluene (BHT) and its derivatives was investigated by the Ames method using Salmonella typhimurium TA98 and TA100 with or without S9 mix . The compounds were not mutagenic in either indicator strain at concentrations ranging from 50 to 330 micrograms/plate (SQ: 3,5,3',5'-tetra-tert-butylstilbenequinone; VI-III: unidentified), 500 micrograms/plate (BE: 3,5,3',5'-tetra-tert-4,4'-dihydroxy-1,2-diphenylethylene; VI: 2,6-di-tert-butyl-4-methyl-4-tert-butylperoxy-2,5-cyclohexadienone ; VI-I: unidentified; VI-II: 3-acetyl-2,5-di-tert-cyclopenta-2,4-dienone) and 1000 micrograms/plate (BHT) . The antimutagenic effects of BHT and its derivatives on mutagenesis by chemical agents were investigated in Salmonella typhimurium TA98 and TA100 and Escherichia coli WP-2 hcr- . VI-II suppressed the mutagenesis induced in TA98 and TA100 by 2-(2-furyl)-3-(5-nitro-2-furyl) acrylamide (AF-2) and that induced in WP-2 hcr- by 4-nitroquinoline-1-oxide (4NQO) without decreasing cell viability . In WP-2 hcr-, the mutagenesis induced by AF-2 and ethyl methanesulfonate was also suppressed significantly . Mutations induced by methyl methanesulfonate were slightly inhibited . However, VI-II had no effect on the mutagenesis induced by N-methyl-N'-nitro-N-nitrosoguanidine.

Mutat Res, 1990 Nov, 242(3), 181 - 6
Formation of mutagens during the frying of Hawaiian fish: correlation with creatine and creatinine content; Marsh NL et al.; Compounds mutagenic toward Salmonella typhimurium strain TA98 in the presence of rat-liver homogenates (S9) were formed when fish flesh was fried at 199 degrees C . Three species of Hawaiian fish commonly consumed in Hawaii (skipjack tuna, Katsuwonus pelamis; yellowfin tuna, Neothunnus macropterus; and milkfish, Chanos chanos) were cooked in an electric skillet, along with samples of sole (Microstomus pacificus) . Organic extracts of the fish were tested in the Ames Salmonella mutagenic assay using tester strain TA98 and S9 . Basic organic extracts of fried, but not raw, samples exhibited significant mutagenicity . The levels of mutagenicity were also higher among the red flesh Hawaiian fish ('ahi, aku and awa) than with the white flesh sole . Creatine and creatinine contents were highest in the Hawaiian fish and lower in the sole . Creatine levels in the fish were 50-100 times greater than the creatinine content and varied from a high of 645 mg/100 g wet weight of fish for yellowfin tuna to a low value of 251 mg/100 g for sole . Mutagen levels are only approximately related to creatine/creatinine levels suggesting that other components contained in these fish may be as important as the guanidines in determining the levels of mutagen in the cooked fish.

Mutagenesis, 1990 Nov, 5(6), 583 - 9
Genotoxic activity of nickel subsulphide alpha-Ni3S2; Arrouijal FZ et al.; Four mutagenicity tests of alpha-Ni3S2 were performed: the Ames test on five Salmonella typhimurium strains, HPRT test on V79 cells, in vitro chromosomal aberrations on human lymphocytes and the in vivo micronucleus test in mice . The in vitro tests were carried out without metabolic activation . (i) The Ames test (5-1500 micrograms/plate) demonstrated no mutagenic activity, thus confirming previous observations by other authors . (ii) The HPRT test was carried out under standard conditions (3 h exposure) with alpha-Ni3S2 concentrations from 30 to 1000 micrograms/ml . No significant difference was observed with the control cells . Ultrastructural examination revealed alpha-Ni3S2 binding to the cell membrane . Very few particles were found in the cytoplasm but not in the nucleus . (iii) In vitro metaphase analysis in human lymphocytes were performed after exposure to total alpha-Ni3S2 suspension and to the soluble fraction in culture medium with or without fetal calf serum (FCS) (3-100 micrograms/ml, 24 h exposure) . Nickel concentrations in the soluble fraction were determined by electrothermal atomic absorption spectrometry . A clastogenic effect of alpha-Ni3S2 became evident under all experimental conditions with a significant additional increase of chromosomal aberrations in 20% FCS complemented medium . No difference was observed between total suspension and soluble fraction . (iv) The micronucleus test confirmed the clastogenic effect of alpha-Ni3S2 in vivo after administration of 250 mg/kg (i.p.) . This test revealed a clear increase of micronuclei frequency in polychromatic erythrocytes 24, 48 and 72 h after the treatment . In addition, we observed a statistically significant decrease in the number (%) of polychromatic erythrocytes after 24 and 48 h exposure . The soluble, i.e . cell-entering, fraction seems to play a great part in the clastogenic effect, as has also been shown with other test methods by other authors.

Arch Biochem Biophys, 1990 Nov 1, 282(2), 352 - 7
Hydroperoxidase I catalyzes peroxidative activation of 3,3'-dichlorobenzidine to a mutagen in Salmonella typhimurium; McGowan-Jordan IJ et al.; Dichlorobenzidine can be peroxidatively activated in Salmonella typhimurium Ames tester strains . Mutagenicity is observed when an S . typhimurium strain which is sensitive to frame-shift mutagens is incubated with dichlorobenzidine and hydrogen peroxide . In this paper, we show that the bacterial enzyme, hydroperoxidase I, is responsible for much of this activation . We constructed isogenic tester strains which lack hydroperoxidase I or II, due to Tn10 insertions in the structural genes encoding these proteins . Hydrogen peroxide-dependent mutagenicity of dichlorobenzidine was measured in each strain . A tester strain lacking hydroperoxidase I activity was much less sensitive than was the parent strain . When hydroperoxidase I activity was restored in this strain, via a plasmid-borne copy of the gene encoding the Escherichia coli protein, sensitivity to peroxide-dependent dichlorobenzidine mutagenicity was enhanced.

Am J Vet Res, 1990 Nov, 51(11), 1869 - 72
Effect of T-2 toxin on resistance to systemic Salmonella typhimurium infection of newly hatched chickens; Ziprin RL et al.; Newly hatched chickens were treated with the trichothecene mycotoxin, T-2 toxin, during the first day of life . Control chickens were treated with other agents known to cause immunosuppression--cyclosporine, cyclophosphamide, and aflatoxin . Chickens were infected on day 6 (5 days after treatment with T-2 toxin) by intraperitoneal inoculation with Salmonella typhimurium . Blood samples were collected from treated chickens (noninfected) and used to assess the responsiveness of blood lymphocytes to T-cell or B-cell mitogens, phytohemagglutinin, or lipopolysaccharide, respectively . The T-2 toxin had a profound negative effect on the ability of the chickens to resist salmonellosis, as measured by survival . However, the toxin effect in reducing phytohemagglutinin- and lipopolysaccharide-stimulated mitogenesis, though significant (P greater than 0.05), was not severe . Our data indicate a direct effect of T-2 toxin on native resistance to systemic salmonellosis, which was not accompanied by marked alteration in T- or B-cell responses to mitogenic stimulation.

Proc Natl Acad Sci U S A, 1990 Nov, 87(21), 8432 - 6
Autogenous suppression of an opal mutation in the gene encoding peptide chain release factor 2; Kawakami K et al.; The peptide chain release factor 2 (RF2) gene, prfB, was cloned from Salmonella typhimurium by DNA hybridization using the Escherichia coli prfB probe . The nucleotide and amino acid sequences of prfB are 87.0% and 95.6% homologous between E . coli and S . typhimurium, respectively, including an in-frame premature UGA stop codon at position 26, the site of +1 frameshift for mature RF2 synthesis . The supK584 mutation, which had been isolated as a recessive UGA suppressor in S . typhimurium, caused an opal (UGA) substitution at amino acid position 144 in the prfB gene . Complementation, reversion, and gene fusion analyses led to the conclusion that supK is a S . typhimurium RF2 mutation and this opal RF2 mutation generates a UGA suppressor activity, presumably because of inefficient translation termination due to the reduced cellular level of RF2 . In fact, suppression of the supK opal mutation results from a form of autogenous control of RF2 synthesis.

Mutat Res, 1990 Nov, 245(3), 165 - 9
Chirality-dependent DNA reactivity as the possible cause of the differential mutagenicity of the two components in an enantiomeric pair of epoxides; Seiler JP; Chemical compounds containing an epoxy group are very reactive substances and, in many cases, they therefore exhibit strong mutagenic properties . Very often such epoxides contain an asymmetric C atom and thus exist as racemic mixtures of optical isomers, the so-called R- and S-enantiomers . It is well known that in many cases a biological activity resides completely in one of the two enantiomeric forms of a molecule . Also, the R- and S-enantiomeric forms of epoxystyrene exhibit different mutagenic activities in Salmonella typhimurium TA100, although their chemical reactivity does not differ to a recognizable extent . Neither could the higher mutagenic activity of the R-epoxystyrene be attributed to a slower enzymatic hydrolysis reaction . Thus, the intrinsic potential for eliciting mutagenic responses may not be the same for the two enantiomers, as there is evidence of qualitative differences in the binding to DNA, pointing strongly to an intrinsic difference in mutagenic activity of the two enantiomers.

J Infect Dis, 1990 Nov, 162(5), 1096 - 106
Salmonella interactions with polarized human intestinal Caco-2 epithelial cells; Finlay BB et al.; Polarized monolayers of the human intestinal epithelial Caco-2 cell line were grown on permeable filters and infected apically with either Salmonella choleraesuis or Salmonella typhimurium . Both Salmonella species penetrated through the monolayer, requiring 2 h before appearing in the basolateral medium . Both species caused a loss in transepithelial resistance by 3-4 h, and the monolayer's integrity was completely disrupted by 6 h . Scanning and transmission electron microscopy revealed that the bacteria interacted with well-defined apical microvilli and caused disruptions in the brush border, including elongation and denuding of the microvilli . The cytoplasm was also disrupted locally, with blebs protruding from the apical surface . The bacteria entered (invaded) these cells and were enclosed in membrane-bound vacuoles within the cytoplasm . By 6 h there were many bacteria within most Caco-2 cells, and these organisms caused serious cytopathic consequences . These morphologic observations correlated well with animal infection models, indicating that this in vitro system will be useful to study pathogens that interact with human intestinal epithelia.

Infect Immun, 1990 Nov, 58(11), 3724 - 30
Rapid membrane permeabilization and inhibition of vital functions of gram-negative bacteria by bactenecins; Skerlavaj B et al.; Bactenecins are a class of arginine-rich antibacterial peptides of bovine neutrophil granules . Two bactenecins with approximate molecular weights of 5,000 and 7,000 designated Bac5 and Bac7, respectively, exert in vitro a potent bactericidal activity toward several gram-negative bacteria (R . Gennaro, B . Skerlavaj, and D . Romeo, Infect . Immun . 57:3142-3146, 1989) . We have now found that this activity shows an inverse relationship to the ionic strength of the medium and is inhibited by divalent cations and greatly potentiated by lactoferrin . Under conditions supporting marked bactericidal activity, the two peptides cause a rapid increase in the permeability of both the outer and inner membranes of Escherichia coli, as shown by unmasking of periplasmic beta-lactamase and of cytoplasmic beta-galactosidase . In addition, the two bactenecins inhibit the respiration of E . coli and Klebsiella pneumoniae but not of Bac5- and Bac7-resistant Staphylococcus aureus . Furthermore, they induce a drop in ATP content in E . coli, K . pneumoniae, and Salmonella typhimurium and a marked decrease in the rates of transport and incorporation of {3H}leucine and {3H}uridine into E . coli protein and RNA, respectively . In general, all these effects become evident within 1 to 2 min and reach their maximal expression within about 5 min . Overall, these data strongly suggest that the decrease in bacterial viability is causally related to the increase in membrane permeability and the subsequent fall in respiration-linked proton motive force, with the attendant loss of cellular metabolites and macromolecular biosynthesis ability.

Carcinogenesis, 1990 Nov, 11(11), 1921 - 6
The initiator tRNA acceptance assay as a short-term test for carcinogens . 6 . Results with 78 polycyclic aromatic compounds; Hradec J et al.; A total of 78 polycyclic aromatic compounds (PAH), including pure hydrocarbons, PAH metabolites, aromatic amines and nitroarenes, were tested in the initiator tRNA acceptance assay (tR assay) for carcinogens . Among the pure hydrocarbons, all strong carcinogens were highly active in the tR assay . Some weak carcinogens showed moderate positive responses, others as well as all possible non-carcinogens were inactive . Various PAH metabolites, including phenols, dihydrodiols, arene oxides, dihydrodiol epoxides, quinones and benzylic sulfate esters, were positive as well . Strikingly, however, their effects rarely reached the levels observed with the strong carcinogens among the pure hydrocarbons . Moreover, the correlation with carcinogenicity was less clear, partially due to limitations in the available carcinogenicity data . The activities in the tR assay were also compared with the mutagenicity in Salmonella typhimurium . No appreciable correlation was observed . For example, trans-9,10-dihydroxy-9,10-dihydrobenzo{c}chrysene, in the absence of a mammalian metabolic system, was highly active in the tR assay, but non-mutagenic . Upon addition of rat liver enzymes, the reverse result was obtained . syn-Benzo{c}chrysene-9,10-dihydrodiol-11,12-oxide, on the other hand, was a potent direct mutagen, but required the presence of liver microsomes for a positive response in the tR assay . Thus, the metabolic basis for these two activities is different, and not yet understood for the tR assay . The partial correlations in the tR assay and in the Salmonella mutagenicity assay with carcinogenicity, and the pronounced discrepancies between these in vitro tests, may suggest that they detect different mechanisms involved in carcinogenicity . However, the tR assay was less predictive for the carcinogenicity of PAHs as compared to the previously investigated N-nitroso compounds and mycotoxins.

Vet Immunol Immunopathol, 1990 Nov, 26(3), 237 - 50
Establishment and characterization of a chicken mononuclear cell line; Qureshi MA et al.; A new chicken mononuclear cell line (MQ-NCSU) has been established . The starting material used to initiate this cell line was a transformed spleen from a female Dekalb XL chicken which had been experimentally challenged with the JM/102W strain of the Marek's disease virus . After homogenization, a single cell suspension of splenic cells was cultured using L.M . Hahn medium supplemented with 10 microM 2-mercaptoethanol . Under these culture conditions, a rapidly proliferating cell was observed and then expanded after performing limiting dilution cultures . These cells were moderately adherent and phagocytic for sheep red blood cells and Salmonella typhimurium . When tested against a panel of monoclonal antibodies (mAb) using the flow cytometry, MQ-NCSU cells stained readily with anti-chicken monocyte specific (K-1) mAb but did not stain with mAb detecting T-helper, T-cytotoxic/suppressor, and NK cells . MQ-NCSU cells expressed very high levels of Ia antigens and transferrin receptors . In addition, cell-free supernatant obtained from MQ-NCSU culture contained a factor which exhibited cytolytic activity against tumor cell targets . Based on their cultural, morphological, and functional characteristics and mAb reactivity profile, we conclude that MQ-NCSU cell line represents a malignantly-transformed cell which shares features characteristic of cells of the mononuclear phagocyte lineage.

J Bacteriol, 1990 Nov, 172(11), 6599 - 601
Molecular analysis of an IS200 insertion in the gpt gene of Salmonella typhimurium LT2; O'Reilly C et al.; A strain of Salmonella typimurium LT2 has been isolated which carries an insertion of approximately 700 bp in the gpt gene . The insertion in the gpt gene was shown to be the Salmonella-specific element IS200 . The mutation in strain CR1 arose without selection during storage and is only the second phenotypically identified mutation caused by the insertion of IS200.

Infect Immun, 1990 Nov, 58(11), 3706 - 10
Characterization of defensin resistance phenotypes associated with mutations in the phoP virulence regulon of Salmonella typhimurium; Miller SI et al.; The defensin sensitivities of Salmonella typhimurium strains with mutations in the phoP/phoQ two-component virulence regulon were tested by using purified defensins NP-1 and NP-2 . Strains with mutations in either gene of the regulatory pair (phoP {transcriptional activator} or phoQ {membrane sensor kinase}) had increased sensitivities to defensin . The predicted periplasmic domain of the PhoQ protein contained a markedly anionic domain that could interact with cationic proteins and that could be responsible for resistance to defensin . Because insertion mutations in phoP are polar on phoQ, we constructed strains that expressed the PhoQ protein in the absence of PhoP to test whether resistance to defensin requires only the phoQ gene product . We found that resistance to defensin requires the function of both components of this regulatory system, because strains expressing PhoQ without PhoP were still markedly sensitive to defensins . This implied that a pag (phoP-activated gene) product is responsible for defensin resistance . We also tested for the ability of defensins NP-1, NP-5, and HNP-1 to activate pag expression and found that these peptides have no effect . Defensin resistance is not the only virulence characteristic controlled by the PhoP-PhoQ regulon because mutations in pagC, as well as ones in the phoP locus that resulted in constitutive pag activation (phenotype PhoPc), had no effect on defensin resistance, even though they rendered the organism avirulent and deficient in survival within macrophages . The virulence defect conferred by mutations in the phoP-phoQ two-component regulatory system is not completely explained by alterations in resistance to cationic proteins and involves the control of other proteins necessary for S . typhimurium survival within macrophages.

Mutat Res, 1990 Nov, 245(3), 151 - 5
Cloning of the E . coli O-acetylserine sulfhydrylase gene: ability of the clone to produce a mutagenic product from azide and O-acetylserine; Owais WM et al.; The gene coding for O-acetylserine sulfhydrylase (OASS) from E . coli K12 was cloned into the vector pBR322 plasmid and expressed in a cysk mutant strain of E . coli that is deficient in O-acetylserine sulfhydrylase (OASS-) . The clone containing the OASS gene was selected by using tetracycline-ammonium bismuth citrate medium . Retransformation of the hybrid plasmid into competent cysk mutant cells resulted in the recovery of a clone containing normal levels of O-acetylserine sulfhydrylase . Negative selection of retransformed cysk cells on 1,2,4-triazole plates resulted in the complete inhibition of growth indicating the presence of a functional OASS gene . The ability of the new clone to convert azide to its mutagenic metabolite was tested . Cultures of the clone cells containing significant levels of OASS activity were able to produce a mutagenic product from azide and O-acetylserine as tested on Salmonella typhimurium TA1530 . This cloning method could be applied also to clone the same gene from eukaryotic sources.

Microb Pathog, 1990 Nov, 9(5), 315 - 29
Biological and immunological characterization of a cloned cholera toxin-like enterotoxin from Salmonella typhimurium; Prasad R et al.; A chromosomal DNA fragment, encoding an enterotoxin gene of Salmonella typhimurium Q1, was cloned into bacteriophage EMBL3 and plasmid vector pBR322 . The recombinant clones lambda B8 and pC1 were identified using a synthetic oligonucleotide probe made to the B subunit region of the cholera toxin gene (ctx) . Cell lysates of Escherichia coli VCS257 {lambda B8} induced fluid secretion in rabbit intestinal loops, while lysates of E . coli DH5 alpha {pC1} failed to elicit an enterotoxic response in this model . Both lysates and partially purified preparations elongated Chinese hamster ovary (CHO) cells, elevated cellular cAMP and PGE2, and bound to ganglioside GM1 . The biological activity associated with the cloned enterotoxin was neutralized by monospecific antiserum to cholera toxin (CT) . Immunoblots of pC1 and lambda B8 lysates probed with anti-CT, exhibited a 30 kDa protein similar to that of pJM17, which carried the ctx gene . Under non-dissociating conditions, anti-CT immunoblots of the same lysates revealed two proteins, one corresponding in size to the holotoxin and the other to CT-A . When analysed by DNA-directed protein synthesis in vitro, both pC1 and lambda B8 DNA expressed two unique proteins (30 and 11 kDa) similar to that of pJM17.

Tsitol Genet, 1990 Nov-Dec, 24(6), 41 - 5
{Criteria of allowance for the mutagenic effectors in the Ames test}; Dugan AM et al.; Mutagenic activity of water pollutants on test-strains Salmonella typhimurium was studied . Results obtained from these studies were evaluated by the Dunnet method of multiple comparisons and the obtained data were compared with the value of excess of the colonies number in the experiment over control . The purpose of this comparison is to determine a ration of excess in the number of revertant colonies in the experiment above a control, under which a portion of the statistically significant results will constitute 90 per cent and more . Statistically significant results occur in 100% of cases when the number of revertant colonies in the experiment variants is 2.2 times as high as in control ones for strains TA 1535 and TA 1538, 2.0 times--for strain TA 98 and 1.8 times--for strain TA 100.

Res Microbiol, 1990 Nov-Dec, 141(9), 1039 - 59
The maltoporin of Salmonella typhimurium: sequence and folding model; Francoz E et al.; The sequence of the lamB gene from Salmonella typhimurium was determined . It encodes the precursor to the LamB protein from S . typhimurium (pre-LamBS.t.; 452 residues) which presents extensive homologies with the pre-LamB protein from Escherichia coli (pre-LamBE.c.; 446 residues) . The first third of pre-LamBS.t . is the most conserved, with 4% changes and strict identity between the signal peptides . The last two-third contains five "variable" segments where more than 50% of the residues are changed with respect to LamBE.c. . The three first variable segments are 8 to 14 residues long and contain only substitutions, while the two more distal ones are 24 and 29 residues long and also include insertions and deletions . It is remarkable that the variable segments correspond essentially to regions predicted to be extramembranous loops on our 2D folding model for LamBE.c.; they alternate with conserved predicted transmembranous segments . Four of the variable regions were predicted to be cell-surface-exposed loops on the basis of genetic and immunological data, while one of them (region II) was predicted to be periplasmic on the sole basis of folding rules . The LamB protein from S . typhimurium can substitute for the LamB protein from E . coli for maltodextrins binding and transport, but not for infection by any of the known E . coli phages using LamBE.c . for adsorption . A tetrapeptide, RGDS, assumed to be responsible for mammalian cell aggregation by LamBE.c . is conserved in LamBS.t., suggesting that it could have a functional role . The conservation of the binding and transport activity can be accounted for by the conservation of the regions known to be directly involved, namely the first third of the protein and a region corresponding to 352 to 374 of LamBS.t. . The phage resistance can be attributed to the variability of the four cell-surface-exposed loops previously identified as essential for phage adsorption . These results, together with those obtained with polyclonal and monoclonal antibodies directed against known LamB regions, strongly support the folding model presented for LamBE.c . and the idea that it can essentially be extended to LamBS.t., except perhaps for a region between residues 155 and 245 . We propose that the existence of variable regions is due essentially, and perhaps only, to the local lack of structural constraints in the protein . The intergenic region between lamB and the following gene, malM, comprises conserved segments, including one palindromic unit.

Farmakol Toksikol, 1990 Nov-Dec, 53(6), 54 - 5
{The effect of triamcinolone acetonide on the liver mitochondria in endotoxemia}; Natanzon LV et al.; Endotoxin Salmonella typhimurium (LD50) was administered intraperitoneally to mice . It was shown that triamcinolone acetonide in a dose of 1 mg/kg living weight administered to mice 1 hour before endotoxin administration completely prevents the death of the animals and decreases the level of changes in the activities of enzymes of glutamate dehydrogenase, succinate dehydrogenase, monoaminoxidase, cytochrome oxidase in the liver mitochondria in endotoxemia . The level of lipid peroxidation in mitochondria during endotoxemia against the background of triamcinolone acetonide action is close to control . The use of triamcinolone acetonide in the absence of the effect of endotoxin results in an insignificant damage of mitochondrial membranes.

APMIS, 1990 Nov, 98(11), 1015 - 21
Experimental Salmonella typhimurium infections in rats . III . Transfer of immunity with primed lymphocyte subpopulations; Hougen HP et al.; The protective effect of primed lymphocytes against a lethal dose of Salmonella typhimurium was studied in athymic and euthymic LEW rats . Primed lymphocytes were obtained by inoculating euthymic and thymus-grafted animals with a non-lethal dose of Salmonella typhimurium . Four weeks after the infection, spleen lymphocytes were separated by panning technique and antibody-coated magnetic microsphere separation using antibodies to pan T and pan B lymphocytes and subsequent sorting in a fluorescence activated cell sorter by means of monoclonal antibodies against CD4+ and CD8+ cells . Euthymic and athymic rats were injected with different doses of primed pan B, pan T, CD4+ and CD8+ T lymphocytes before inoculation with a lethal bacterial dose . Most of the animals treated with pan B, pan T or CD8+ cells died within two weeks . After treatment with primed CD4+ cells, only six of 39 animals died . Doses as low as 10(4) cells from both euthymic or thymus-grafted animals were effective, and athymic and euthymic recipients survived equally well . Four weeks after the infection both athymic and euthymic animals housed very few bacteria and had high antibacterial antibody titres . The percentages of splenic and lymph node CD4+ cells in the athymic rats were comparable to those found in the euthymic animals . The study shows that primed CD4+ lymphocytes even in very low doses are able to induce immunity against a Salmonella typhimurium infection.

J Bacteriol, 1990 Nov, 172(11), 6217 - 22
Genes on the 90-kilobase plasmid of Salmonella typhimurium confer low-affinity cobalamin transport: relationship to fimbria biosynthesis genes; Rioux CR et al.; A cloned fragment of Salmonella typhimurium DNA complemented the defect in cobalamin uptake of Escherichia coli or S . typhimurium btuB mutants, which lack the outer membrane high-affinity transport protein . This DNA fragment did not carry btuB and was derived from the 90-kb plasmid resident in S . typhimurium strains . The cobalamin transport activity engendered by this plasmid had substantially lower affinity and activity than that conferred by btuB . Complementation behavior and maxicell analyses of transposon insertions showed that the cloned fragment encoded five polypeptides, at least two of which were required for complementation activity . The nucleotide sequence of the coding region for one of these polypeptides, an outer membrane protein of about 84,000 Da, was determined . The deduced polypeptide had properties typical of outer membrane proteins, with an N-terminal signal sequence and a predicted preponderance of beta structure . This outer membrane protein had extensive amino acid sequence homology with PapC and FaeD, two E . coli outer membrane proteins involved in the export and assembly of pilus and fimbria subunits on the cell surface . This homology raises the likelihood that the observed cobalamin transport did not result from the production of an authentic transport system but that overexpression of one or more outer membrane proteins allowed leakage of cobalamins through the perturbed outer membrane . These results also suggest that the 90-kb plasmid carries genes encoding an adherence mechanism.

Gene, 1990 Oct 30, 95(1), 17 - 23
Nucleotide sequence and analysis of the Vibrio alginolyticus sucrose uptake-encoding region; Blatch GL et al.; The nucleotide sequence of the Vibrio alginolyticus sucrose uptake-encoding region was determined, and contained two genes, scrA and scrK . The scrA gene encodes an enzyme IISucrose (EIIScr) protein of the phosphoenolpyruvate dependent phosphotransferase system and the scrK gene encodes a fructokinase . The deduced amino acid (aa) sequence for the V . alginolyticus EIIScr protein was homologous with the EIIScr proteins from Streptococcus mutans, Salmonella typhimurium (pUR400 system) and Bacillus subtilis . The deduced aa sequence for the V . alginolyticus fructokinase was homologous with the Escherichia coli enzymes, 6-phosphofructokinase (isoenzyme 2) and ribokinase . Transposon phoA mutagenesis experiments indicated that the EIIScr protein was a membrane-bound protein with a region that extended into the periplasm.

J Mol Biol, 1990 Oct 20, 215(4), 489 - 92
Preliminary crystal structure analysis of an Fab specific for a Salmonella O-polysaccharide antigen; Rose DR et al.; The Fab from an IgG1, lambda murine monoclonal antibody with specificity for the O-polysaccharide antigen of Salmonella typhimurium has been crystallized in the absence and presence of hapten . The conditions for crystal growth were vapor diffusion equilibration with 16 to 23% polyethylene glycol 8000 solutions . Data have been collected from crystals of the complex in space group P212121, a = 60.6 A, b = 111.3 A, c = 61.1 A, and refinement of a molecular replacement solution is underway.

J Immunol, 1990 Oct 15, 145(8), 2427 - 33
Polyclonal activation of rat B cells . II . Dextran sulfate as a cofactor in mitogen-induced and antigen-induced differentiation of rat B lymphocytes; Minchin SA et al.; Salmonella typhimurium mitogen (STM) is a polyclonal activator of rat B lymphocytes, triggering them to proliferate, but not differentiate, to antibody-secreting cells . When lymphokines in the form of a supernatant from Con A-stimulated splenocytes (CAS) are added to B cell cultures activated by STM, only a small number of cells are driven to differentiate . Only with the addition of a third signal provided by the polyanionic polysaccharide dextran sulfate (DXS) is significant rat B cell differentiation observed . In this study, we have shown that this requirement for DXS is not unique to the STM mitogen . LPS, Staphylococcus aureus Cowan I-fixed cells, and anti-Ig antibody all induced rat B cell proliferation with little differentiation, even in the presence of CAS . DXS was necessary to induce differentiation in all cultures costimulated with mitogen and CAS . The requirement for DXS for optimal B cell differentiation is also observed with other lymphokine preparations such as the supernatants from PMA-stimulated EL-4 cells and PHA-stimulated human T cells . Furthermore, this augmentative effect of DXS in rat B cell differentiation was not confined to polyclonal activation systems . Ag-specific IgG secretion was also increased when DXS was added to Ag and CAS costimulated cultures of B cells harvested from the draining lymph nodes of rats immunized with DNP-keyhole limpet hemocyanin . Within the polyclonal activation system, a method of staged additions of STM, DXS, and CAS to B cell cultures was used to investigate the role of DXS during B cell differentiation . Optimal differentiation occurred only when DXS was present in the B cell cultures in conjunction with CAS . The augmentation in differentiation seen with DXS did not appear to be due to the recruitment of an additional CAS-responsive B cell subset, because cycling, low density B cell blasts showed large increases in IgM secretion with subsequent exposure to DXS and CAS . These studies suggest tha DXS acts as a cofactor to various differentiation factors, augmenting polyclonal and Ag-specific rat B cell differentiation . The relevance of DXS to in vivo immune responses is discussed.

Antimicrob Agents Chemother, 1990 Oct, 34(10), 1949 - 54
Antimicrobial activity of betaine esters, quaternary ammonium amphiphiles which spontaneously hydrolyze into nontoxic components; Lindstedt M et al.; A series of quaternary ammonium compounds that are esters of betaine and fatty alcohols with hydrocarbon chain lengths of 10 to 18 carbon atoms were tested with respect to antimicrobial activities and rates of hydrolysis . When the tetradecyl derivative was tested against some selected microorganisms, the killing effect was comparable to that of the stable quaternary ammonium compound cetyltrimethylammonium bromide . At higher pH values, both the antimicrobial effect and the rate of hydrolysis of the esters increased . However, whereas at pH 6 greater than 99.99% killing of Salmonella typhimurium was achieved with 5 micrograms/ml in 3 min, the rate of hydrolysis was less than 20% in 18 h . At pH 7, a similar killing effect was achieved in 2 min and 50% hydrolysis occurred in ca . 5 h . Thus, it is possible to exploit the rapid microbicidal effect of the compounds before they hydrolyze . The rate of hydrolysis was reduced by the presence of salt . The bactericidal effect of the betaine esters increased with the length of the hydrocarbon chain of the fatty alcohol moiety up to 18 carbon atoms . Since the hydrolysis products are normal human metabolites, the hydrolysis property may extend the use of these quaternary ammonium compounds as disinfectants and antiseptics for food and body surfaces.

Mol Gen Genet, 1990 Oct, 224(1), 155 - 9
Specific truncations of an acetolactate synthase gene from Brassica napus efficiently complement ilvB/ilvG mutants of Salmonella typhimurium; Wiersma PA et al.; The expression of an acetolactate synthase (ALS) gene isolated from the cruciferous plant Brassica napus was investigated in Salmonella typhimurium . Using an expression plasmid containing the highly active trc (trp-lac) promoter, several plant ALS constructs were made containing successive in-frame truncations from the 5' end of the coding region . Functional complementation by these plant ALS constructs of a S . typhimurium mutant devoid of ALS enzymic activity was assayed on minimal medium . Truncations which eliminated a large portion of the transit peptide coding sequence proved to act as efficient ALS genes in the bacterial host . Truncations close to the putative processing site of the plant protein were inactive in the complementation test . A full length copy of the gene, including the entire transit peptide coding region, was also inactive . The efficiency of the complementation, estimated by comparison to the growth rate of wild-type S . typhimurium, was found to correlate with levels of ALS activity in the transformed bacteria . Specific mutations, known to produce herbicide resistance in plants, were introduced into the truncated ALS coding sequence by site-directed mutagenesis . When expressed in bacteria these constructs conferred a herbicide resistance phenotype on the host . The potential of this system for mutagenesis and enzymological studies of plant proteins is discussed.

Mol Gen Genet, 1990 Oct, 224(1), 147 - 51
Nucleotide sequence of katG of Salmonella typhimurium LT2 and characterization of its product, hydroperoxidase I; Loewen PC et al.; The nucleotide sequence of katG from Salmonella typhimurium was determined revealing an open reading frame of 2181 bp that could encode a 727 amino acid protein . The predicted sequence of the encoded hydroperoxidase I (HPI) was found to be 90% similar to HPI from Escherichia coli and was one amino acid longer . The physical and enzymatic properties of HPI from both Salmonella typhimurium and Escherichia coli were found to be virtually identical despite the 10% divergence in sequence.

Poult Sci, 1990 Oct, 69(10), 1809 - 12
Fifty percent colonization dose for Salmonella typhimurium administered orally and intracloacally to young broiler chicks; Cox NA et al.; One and 3-day-old chicks were challenged with varying levels of Salmonella typhimurium by gavage or intracloacal administration . Chicks were killed 5 days postchallenge, and ceca were analyzed for the presence of S . typhimurium . About 100-fold fewer S . typhimurium cells were required to colonize young chicks by the intracloacal route than by gavage . It was hypothesized that the low pH of the upper gastrointestinal tract contributes to the higher levels of Salmonella required to colonize young chicks via the oral route . The pH measurements in the gizzard of freshly killed chicks were variable, but most were low enough to be bactericidal . Presence of salmonellae in the hatchery environment and the low level of cells (2 cfu) required to colonize young chicks via cloacal challenge suggest that day-of-hatch chicks may be at a high colonization risk from salmonellae in the hatchery.

Zhonghua Liu Xing Bing Xue Za Zhi, 1990 Oct, 11(5), 284 - 7
{A survey of nosocomial infection by Salmonella typhimurium}; Shi J; 140 cases of infections by Salmonella typhimurium were studied from June 1987 to the end of 1988 . Among those patients 56% of the cases were hospital-acquired . The nosocomial infection rate of the disease in the hospital was 14.6% . The majority of these cases were found in infants and young children . The sources of infections were the sporadic out patients . Improper isolation and disinfection caused the spreading of the infection in the hospital . As we noticed, nosocomial infection by S . typhimurium could occur during the whole year and had an increased incidence in winter . Due to pathogens isolated from those patients were highly resistant to antibiotics so the nosocomial infection could delay the hospitalization time, therefore how to control it became an important aspect of the hospital.

Vet Immunol Immunopathol, 1990 Oct, 26(2), 115 - 23
Preliminary data on efficacy of Mycoplasma gallisepticum vaccines containing different adjuvants in laying hens; Barbour EK et al.; Chickens were vaccinated subcutaneously twice, at 13 and 17 weeks of age . The vaccines used were the whole organisms of Mycoplasma gallisepticum (MG) adjuvanted with multilamellar positively charged (MPC) liposomes or oil-emulsion . Other chickens received the same bacterins but supplemented with Salmonella typhimurium cell wall protein mitogen (STP) (50 micrograms/dose) . At 21 weeks of age, each bird was challenged in the right and left caudal thoracic air sacs . The challenge dose/chicken was 1.3 x 10(5) CFU of MG (R-strain) . A significant immunoglobulin (Ig) response specific to MG was observed in sera of chickens collected 3 weeks after the first and second vaccination with MG adjuvanted with MPC liposomes or oil-emulsion . The same two treatments had highly significant MG-titers in eggs collected during the first and second month post challenge . Both groups had highly significant protection (P less than 0.05) against MG transmission in eggs layed during the first month post challenge . Vaccination with MG organisms adjuvanted to MPC liposomes or oil-emulsion resulted in higher egg production, during the first month following challenge, in comparison to the unvaccinated-challenged birds; the same two groups had higher egg production in the second month following challenge compared to unvaccinated-challenged birds, but not significantly different (P greater than 0.05) . The addition of STP to bacterins containing MG organisms adjuvanted to MPC liposomes or oil-emulsion, resulted in a significant reduction (P less than 0.05) of the Ig-specific to MG in sera and in a significant drop in egg production (P less than 0.05) during the first month following challenge.

Antonie Van Leeuwenhoek, 1990 Oct, 58(3), 157 - 61
The OxyR regulon; Storz G et al.; Treatment of Salmonella typhimurium and Escherichia coli cells with low doses of hydrogen peroxide results in the induction of thirty proteins and resistance to killing by higher doses of hydrogen peroxide . The expression of nine of the hydrogen peroxide-inducible proteins, including catalase, glutathione reductase and a novel alkyl hydroperoxide reductase is controlled by the positive regulator oxyR . OxyR is homologous to the LysR-NodD family of bacterial regulatory proteins and binds to the promoters of oxyR-regulated genes . The oxidized but not reduced form of the OxyR protein activates transcription of oxyR-regulated genes in vitro suggesting that oxidation of the OxyR protein brings about a conformational change by which OxyR both senses and transduces an oxidative stress signal to RNA polymerase.

Vaccine, 1990 Oct, 8(5), 425 - 37
Potential use of live viral and bacterial vectors for vaccines . WHO meeting, Geneva, 19-22 June, 1989; Flow cytofluorometric studies on the alteration of leukocyte populations in blood and milk during endotoxin-induced mastitis in cows; Department of Obstetrics and Gynaecology, Swedish University of Agricultural Sciences, UppsalaAlterations in the various leukocyte populations in milk, blood, and mammary lymph were studied by use of the flow cytometric method during acute mastitis episodes induced by endotoxin infusion (50 micrograms of lipopolysaccharide of Salmonella typhimurium SH 4809) via the teat canal . Lymph samples were collected via a semipermanent catheter from an afferent duct to the supramammary lymph node . Milk somatic cell count increased at 4 hours after infusion of endotoxin . Neutrophils were the predominant cell population for up to 59 hours after infusion . Numbers of lymphocytes and monocytes-macrophages in milk also increased after the endotoxin infusion . The total cell count in milk started to decrease during the third postinfusion day and returned to preinfusion values during the fourth day . Lymphocyte numbers remained high for about 1 week after the infusion, and lymphocytes were the predominant cell population between postinfusion days 4 and 8 . Total blood leukocyte count decreased during the first 6 hours after infusion, followed by an increase until postinfusion hour 31 . The proportion of neutrophils in blood increased during the first day, whereas that of lymphocytes decreased . Lymph flow rate and leukocyte numbers in lymph increased after endotoxin infusion . The proportion of neutrophils in the lymph increased during the first 6 hours, whereas that of lymphocytes decreased . After postinfusion hour 6, the inverse course of events was seen.

Mutat Res, 1990 Oct, 242(2), 135 - 42
Absence of genotoxic activity of penbutolol in bacterial and mammalian cell screening systems; Muller W et al.; The genotoxic potential of the beta-adrenergic blocker penbutolol was assessed using the Ames and HGPRT tests, unscheduled DNA synthesis (UDS) and alkaline elution assays . In the Ames test, penbutolol was tested for cytotoxicity and genotoxic activity in concentration ranges of 0.8-500 micrograms/plate and 0.1-125 micrograms/ml in the HGPRT, UDS and alkaline elution assays . In the Ames test penbutolol showed significant toxicity above 500 micrograms/plate . In the mammalian cells (V79) used for the HGPRT test and A459 cells used for alkaline elution and UDS assays, penbutolol was cytotoxic at concentrations above 30 micrograms/ml . In another series of experiments, male Wistar rats were treated i.p . with penbutolol (1, 10 and 100 mg/kg) and after 2 h liver nuclei were isolated and formation of single DNA-strand breaks was measured . The results of the present study demonstrate the absence of genotoxic activity of penbutolol in the 5 strains of Salmonella typhimurium (TA98, TA100, TA1535, TA1537 and TA1538) and in the strain of Escherichia coli WP2 uvrA in the presence or absence of metabolic activation . In V79 cells, penbutolol showed no mutagenic effects at the HGPRT locus in the presence or absence of metabolic activation . Additionally, no significant incorporation of {3H}thymidine into the DNA in the UDS test or formation of DNA-strand breaks in the alkaline elution assay was detected in the non-toxic concentration range of penbutolol with or without metabolic activation . Furthermore, penbutolol did not cause DNA damage in liver nuclei isolated from penbutolol-treated rats.

Zentralbl Veterinarmed B, 1990 Oct, 37(8), 615 - 23
On the importance of bacterial L-forms in pigeons; Kiessling D et al.; Following a definition of bacterial L-forms and a literature review on introduction and reversion of bacteria to and from L-forms, respectively, the results of a study comprising 587 samples (316 pigeons and 271 pigeon eggs) are reported . As a control 25 free living pigeons and 25 eggs of those pigeons were used, because antibiotic treatment of these could be excluded . From 79 samples (75 pigeons and 4 eggs) Salmonella typhimurium var . copenhagen (STMC) was isolated (none from the urban pigeons), of them 11 in the L-form from joints and organs and 3 from eggs . 325 of other bacterial isolates were found as L-forms (= approx . 40%) . Out of 168 serum samples investigated, 33.9% showed antibodies against STMC . Corresponding antibodies could only be demonstrated in 73.4% of the pigeons with a STMC isolate . The occurrence of L-forms explains resistance to therapy and the failure of vaccines . The high frequency of L-forms is probably an indication of an inconsequential use of antibiotics in managing pigeon diseases.

Mutat Res, 1990 Oct, 245(2), 93 - 8
Investigations on mutagenicity and genotoxicity of pentamidine and some related trypanocidal diamidines; Stauffert I et al.; Pentamidine, DAPI and some related compounds (DAI, 6-Br-AI, DPTN, DIPI, 3-Am-DAI, DiaPBF) were investigated in 2 different screening test systems for their potential mutagenic and cytotoxic effects, in the light of their binding to DNA . In the Ames test using Salmonella typhimurium strains TA98 and TA100 with and without metabolic activation no mutagenic effects could be observed . All diamidines tested, except DAI, were toxic at concentrations of 0.5 and 1.0 mumole/plate . In the sister-chromatid exchange (SCE) assay with human peripheral lymphocytes all compounds tested were growth-retarding particularly in the G0 phase . A significant induction of SCEs could only be seen after treatment with the monoamidino compound 6-Br-AI at a concentration of 100 mumole/l . It is concluded from the data obtained that pentamidine and related diamidines in the 2 assays tested show no mutagenic or genotoxic effects, in spite of their tight binding to DNA.

Mutat Res, 1990 Oct, 234(5), 337 - 48
Sensitive method for the detection of mutagenic nitroarenes and aromatic amines: new derivatives of Salmonella typhimurium tester strains possessing elevated O-acetyltransferase levels; Watanabe M et al.; Acetyl-CoA: N-hydroxyarylamine O-acetyltransferase is an enzyme involved in the intracellular metabolic activation of arylhydroxylamines derived from mutagenic nitroarenes and aromatic amines . The acetyltransferase gene of Salmonella typhimurium TA1538 was cloned into pBR322 and the plasmids harboring the gene were introduced into TA98 and TA100 . The resulting strains (YG1024 and YG1029) had about 100 times higher 2-hydroxyamino-6-methyldipyrido{1,2-a:3',2'-d}-imidazole (N-hydroxy-Glu-P-1) O-acetyltransferase activity than TA1538 containing pBR322, and were extremely sensitive to the mutagenic actions of 2-nitrofluorene, 1-nitropyrene, 1,8-dinitropyrene, 2-amino-6-methyldipyrido{1,2-a:3',2-d)-imidazole (Glu-P-1), 2-aminofluorene and 2-aminoanthracene . These results indicate that the new strains permit the efficient detection of the mutagenicity of environmental nitroarenes and aromatic amines.

Mutat Res, 1990 Oct, 232(2), 337 - 43
The mutagenic effects of diacridines and diquinolines in microbial systems; Ferguson LR et al.; Two series of difunctional DNA-intercalating agents (diacridines and diquinolines) were tested for mutagenic properties in Salmonella typhimurium strain TA1537, and for 'petite' mutagenesis activity in Saccharomyces cerevisiae, and also compared in terms of their structural, lipophilic and DNA-binding properties . Diacridines with only a short chain length were monointercalators, while those with an alkyl linker chain longer than C6 were bisintercalators . Although the bisintercalators especially bound very tightly to DNA, none of these compounds was as effective a frameshift mutagen in TA1537 as the parent chromophore 9-aminoacridine . However, the two (monointercalating) diacridines of shortest chain length were still able to cause frameshifts, and this ability returned (albeit weakly) in the bisintercalators of longest chain length . Although 9-aminoacridine showed no ability for 'petite' mutagenesis, the diacridines of longer chain length were very effective in causing this mitochondrial event . In the quinoline series, both the parent chromophore (4-aminoquinoline) and all the diquinolines were weak monointercalators . None of these compounds showed any ability for frameshift mutagenesis, although some were very weak mitochondrial mutagens . It is concluded that linking two acridines produces compounds whose mutagenic properties might have been predicted from our current knowledge of the parent molecules . However, despite a similar ability to intercalate DNA, the diquinolines show no resemblance to acridines in their mutagenic properties.

Mutat Res, 1990 Oct, 232(2), 233 - 41
Structure-activity relationships for the mutagenic activity of tricyclic intercalating agents in Salmonella typhimurium; Denny WA et al.; A total of 25 different tricyclic DNA-intercalating chromophores bearing a common -CONH(CH2)2N(CH3)2 solubilizing sidechain have been compared with the 'classical' frameshift mutagen 9-aminoacridine for their ability to induce revertants in Salmonella typhimurium strain TA1537 (sensitive to frameshift mutation by acridine mutagens) . The compounds showed varying levels of activity in this strain . For the fused linear and fused angular tricyclics, activity varied from zero to similar levels to 9-aminoacridine, but with no discernable relationship between activity and either structure or the measured physico-chemical properties . However, the '2-1' tricyclic compounds had essentially no mutagenic activity . Since several of these compounds have high in vivo antitumor activity, this is useful knowledge.

J Bacteriol, 1990 Oct, 172(10), 5637 - 42
Purification of the Escherichia coli purine regulon repressor and identification of corepressors; Rolfes RJ et al.; The Escherichia coli pur regulon repressor protein was overproduced in a phage T7 expression system . The overexpressed repressor constituted approximately 35% of the soluble cellular protein . Pur repressor was purified to near homogeneity by two chromatographic steps . Hypoxanthine or guanine was required for binding of purified repressor to purF operator DNA . Apparent dissociation constants of 3.4 nM were determined for binding of holorepressor to purF operator and of 1.7 and 7.1 microM were determined for aporepressor interaction with guanine and hypoxanthine, respectively . A requirement for hypoxanthine or guanine for conversion of aporepressor to holorepressor in vitro supports the earlier report (U . Houlberg and K.F . Jensen, J . Bacteriol . 153:837-845, 1983) that these purine bases are involved in regulation of pur gene expression in Salmonella typhimurium and confirms that hypoxanthine and guanine are corepressors.

Epidemiol Infect, 1990 Oct, 105(2), 317 - 23
Phage type and DNA plasmid profile of Salmonella typhimurium isolates in the area of Isernia, Italy; Fantasia M et al.; Thirty-eight Salmonella typhimurium strains isolated from December 1987 to March 1988 in Isernia, Central Italy, were characterized on the basis of their phage type, resistance to antimicrobials and plasmid profiles . According to their phage types, the isolates could be assigned to one of six groups, the prevalent one being PT 195 which accounted for 73.6% of isolates . On the basis of their plasmid content, the isolates could be assigned to one of ten groups . The prevalent plasmid profile (60.0; 6.0; 4.3; 4.0; 3.2 megadaltons) was found in 60.4% of isolates . All the isolates from a particular food (salsicce), and as most of isolates from humans who had consumed this food belonged to phage type 195 and were of the same plasmid profile . The combined use of phage typing and DNA plasmid analysis proved to be a useful tool in identifying epidemiologically related isolates in this investigation.

Epidemiol Infect, 1990 Oct, 105(2), 295 - 305
The epidemiology of Salmonella infection of calves: the role of dealers; Wray C et al.; Salmonellas were detected in the environment of 10 of the 12 calf dealers' premises studied . The cleaning and disinfection routines were often ineffective and salmonellas were isolated from 7.6% and 5.3% of the wall and floor samples before disinfection and 6.8% and 7.6% afterwards . Eight different salmonella serotypes were detected, of which the commonest were Salmonella typhimurium, predominantly phage type DT204C, and S . dublin . Plasmid profiles were used to fingerprint S . typhimurium DT204C and the results indicated that with the exception of one of the premises, prolonged salmonella-persistence in the environment was not occurring . Three separate epidemics of salmonellosis in calves were studied by use of plasmid profile analysis . The results illustrated the role of delers, and their subcontractors, in the dissemination of salmonellas . The study concludes with suggestions for methods to reduce the spread of salmonellas in the calf marketing chain.

Mutat Res, 1990 Oct, 245(2), 129 - 33
Reduction of the mutagenicity of lead chromate-based pigments by encapsulation with silica; Connor TH et al.; 13 lead chromate-based pigments were assayed for mutagenicity and toxicity using Salmonella typhimurium TA100 . The compounds were assayed with and without S9, both in the presence and absence of the chelating agent, nitrilotriacetic acid (NTA) . In general, the use of NTA to solubilize the compounds resulted in mutagenicity and/or toxicity being observed where it had not in the absence of NTA, or being observed at lower concentrations than when water alone was used . Encapsulation of pigments with amorphous silica rendered these pigments non-mutagenic and non-toxic, indicating that the active moieties were biologically unavailable to the bacteria . Varying the percentage of silica encapsulation on one pigment, medium chrome yellow, indicated that 5% encapsulation did not alter the mutagenicity while 10% encapsulation inhibited the mutagenicity without or with NTA.

Mutat Res, 1990 Oct, 245(2), 125 - 8
Fluctuation tests are more sensitive than plate tests in detection of chemicals which cause enhanced excision of transposon Tn10 in Salmonella typhimurium; Hafner LM et al.; Precise excision of transposon Tn10, as judged by reversion of Salmonella typhimurium strain LT2 trp1014::Tn10 to Trp+, was not detectably enhanced following exposure to 9-aminoacridine, 5-azacytidine or mitomycin C in conventional treat-and-plate assays . By contrast, 7/13 chemicals, including 5-azacytidine and mitomycin C, were found to be capable of enhancing precise excision of Tn10 when tested in modified fluctuation assays . Despite earlier reports, precise excision is one activity of transposons which is not therefore refractory to enhancement by chemical mutagens.

Mutat Res, 1990 Oct, 232(2), 305 - 12
Modulation of the control of mutagenic metabolites derived from cyclophosphamide and ifosfamide by stimulation of protein kinase A; Oesch-Bartlomowicz B et al.; The phosphorylation of the 2 major phenobarbital-inducible cytochrome P450 isoenzymes IIB1 and IIB2 was increased in intact hepatocytes by the action of the membrane-permeating cAMP derivative N6,O2'-dibutyryl-cAMP . Under these conditions cyclophosphamide and ifosfamide (which are known to be activated by cytochrome P450 IIB1) were investigated for mutagenicity in Salmonella typhimurium TA1535 and TA100 and for cytotoxicity in TA1535 . Cyclophosphamide and ifosfamide were transformed to mutagenic and cytotoxic metabolites by the hepatocytes . The activation of both drugs to mutagens was markedly reduced after pretreatment of the hepatocytes with the membrane-permeating cAMP derivative N6,O2'-dibutyryl-cAMP . Cyclophosphamide and ifosfamide activation were reduced to 51% and 38% of unstimulated controls respectively, when hepatocytes were incubated for 1 h with N6,O2'-dibutyryl-cAMP in the presence of the phosphodiesterase inhibitor theophylline, and Salmonella typhimurium TA1535 was used . A marked reduction in mutagenicity of cyclophosphamide (35% compared with unstimulated controls) was also observed under different experimental conditions, namely after pretreatment of the hepatocytes with N6,O2'-dibutyryl-cAMP for 1.5 h without theophylline and using Salmonella typhimurium TA100 as target strain . Continued presence of the cytochrome P450 IIB1 and P450 IIB2 inducer phenobarbital in the stimulation medium increased the mutagenicity of cyclophosphamide and led to an even more marked reduction of mutagenicity by pretreatment of the hepatocytes with N6,O2'-dibutyryl-cAMP and theophylline . In order to investigate whether the observed changes were metabolism-related, the ifosfamide metabolite ifosfamide mustard which does not require metabolic activation by cytochrome P450 was studied under the same conditions . Its mutagenicity was indistinguishable after incubation with N6,O2'-dibutyryl-cAMP-treated or with unstimulated hepatocytes . Also the metabolic formation of cytotoxic metabolites from cyclophosphamide and ifosfamide but not that of ifosfamide mustard was markedly decreased by pretreatment of the hepatocytes with N6,O2'-dibutyryl-cAMP and theophylline . Thus the stimulation of protein kinase A in intact cells has important consequences for the control of genotoxic and cytotoxic metabolites and represents a fast and short-term regulation of it.

J Immunol, 1990 Oct 1, 145(7), 2281 - 5
Oral Salmonella typhimurium (AroA-) vaccine expressing a major leishmanial surface protein (gp63) preferentially induces T helper 1 cells and protective immunity against leishmaniasis; Yang DM et al.; The gp63 gene of Leishmania major was transformed into the AroA- vaccine strain of Salmonella typhimurium (SL3261) . The construct (SL3261-gp63), which stably expresses the gp63 Ag in vitro, was used to immunize CBA mice by the oral route . Spleen cells from mice inoculated with SL3261-gp63 developed antibody and proliferative T cell response to L . major . They did not express detectable delayed-type hypersensitivity reactivity . The activated T cells are mainly CD4+ and secrete IL-2 and IFN-gamma but no IL-4 . The orally immunized mice developed significant resistance against a challenge L . major infection . We have, therefore, demonstrated the feasibility of oral vaccination against leishmaniasis and that the oral route of antigen delivery via the heterologous carrier may preferentially induce Th1 subsets of CD4+ cells.

J Biol Regul Homeost Agents, 1990 Oct-Dec, 4(4), 157 - 61
Effect of tumor necrosis factor-alpha on infection with Salmonella typhimurium in a mouse model; Degre M et al.; Mice, inoculated with Salmonella typhimurium, either intraperitoneally (i.p.) or intragastrically (i.g.), developed a systemic infection with a high death rate within a few days after inoculation . Pretreatment of the mice with moderate concentrations of i.p . administered TNF-alpha 24 h before the administration of bacteria reduced the establishment of intracellular infection in the intestinal epithelial cells, and development of bacteremia . The mortality rate was reduced, and the survival time was extended by the same treatment . This effect of TNF-alpha was more pronounced against i.g . than against i.p . inoculated bacteria . The effect was dose dependent, thus concentrations above or below the optimal dose had less effect . No synergistic effect was seen if TNF-alpha was given in combination with interferon-gamma . These results indicate, that TNF-alpha may have a physiological effect in the host defence against facultatively intracellular Gram-negative bacteria.

Protein Eng, 1990 Oct, 4(1), 39 - 43
Structural resemblance between the families of bacterial signal-transduction proteins and of G proteins revealed by graph theoretical techniques; Artymiuk PJ et al.; The first application of a novel technique for the identification of common folding motifs in proteins is presented . Using techniques derived from graph theory, developed in order to compare secondary structure motifs in proteins, we have established that there is a striking resemblance in the tertiary fold of the Salmonella typhimurium Che Y chemotaxis protein and that of the GDP-binding domain of Escherichia coli elongation factor Tu (EF Tu) . These two protein structures are representatives of two major macromolecular classes: CheY is a signal-transduction protein with sequence homologies to a wide range of bacterial proteins involved in regulation of chemotaxis, membrane synthesis and sporulation; whilst EF Tu is one of a family of guanosine-nucleotide-binding proteins which include the ras oncogene proteins and signal-transducing G proteins . The similarity we have found extends far beyond the previously recognized resemblances of each protein's fold to that of a generic nucleotide-binding domain . The lack of significant sequence homology between the two classes of proteins may mean that the common fold of the two proteins constitutes a particularly stable folding motif . However, an alternative possibility is that the strong three-dimensional structural resemblance may be indicative of a remote shared common ancestry between the bacterial signal-transduction proteins and the GDP-binding proteins.

Appl Environ Microbiol, 1990 Oct, 56(10), 3216 - 9
Thermotolerance of Listeria monocytogenes and Salmonella typhimurium after sublethal heat shock; Bunning VK et al.; The effect of prior heat shock on thermotolerance of Listeria monocytogenes and Salmonella typhimurium in broth culture was determined . Bacteria were grown at the permissive temperature of 35 degrees C, sublethally heated at 35 (control), 42, 48, and 52 degrees C (nonpermissive control) for various times, and inactivated at either 57.8 or 52 degrees C . The induction of increased thermotolerance by heat shock, although consistent within each experiment, was generally not significant for L . monocytogenes; the increase was significant for S . typhimurium . Temperature shift experiments with L . monocytogenes suggested that induced thermotolerance was not long lived unless the shock temperature was maintained.

Mutat Res, 1990 Oct, 242(2), 143 - 9
Inhibition of benzo{a}pyrene dihydrodiol epoxide mutagenicity by synthetic analogues of ellagic acid; Josephy PD et al.; Dibenzo{b, d}pyran-6-one, hydroxylated and methoxylated derivatives of this ring system, and some other analogues of the natural product ellagic acid have been synthesized and examined as inhibitors of benzo{a}pyrene dihydrodiol epoxide (BPDE) mutagenicity in Salmonella typhimurium strain TA100 . Some of these new compounds have inhibitory effectiveness comparable to the natural product . On the basis of our results, we suggest qualitative rules for predicting inhibitory activity of ellagic acid analogues.

Infect Immun, 1990 Oct, 58(10), 3425 - 9
Immunization of mice against Plasmodium vinckei with a combination of attenuated Salmonella typhimurium and malarial antigen; Kumar S et al.; Infection with the blood stage of the malaria parasite Plasmodium vinckei is uniformly lethal in mice . We found that immunization of BALB/c mice with a combination of killed P . vinckei antigens and an attenuated (aroA) Salmonella typhimurium strain induces high levels of protection against challenge with live P . vinckei . This is especially significant because, in our previous studies, immunization of mice with killed P . vinckei antigens and adjuvants such as Bordetella pertussis, complete Freund adjuvant, and saponin failed to induce protective immunity . Immunization with attenuated S . typhimurium alone did not provide any nonspecific immunity . In vivo depletion of CD4+ T cells in the mice immunized with attenuated S . typhimurium and P . vinckei antigens caused the loss of their immunity . Expression of this immunity required the presence of a spleen . These results support our previous hypothesis that a blood stage malaria vaccine may need both induction of CD4+ T cells specific for the parasite and modification of the spleen with a vaccine vehicle . Therefore, attenuated Salmonella strains such as the one used in this study, when expressing recombinant malarial antigens, might fulfill this requirement.

J Exp Med, 1990 Oct 1, 172(4), 1083 - 90
Oral Salmonella: malaria circumsporozoite recombinants induce specific CD8+ cytotoxic T cells; Aggarwal A et al.; Oral immunization with an attenuated Salmonella typhimurium recombinant containing the full-length Plasmodium berghei circumsporozoite (CS) gene induces protective immunity against P . berghei sporozoite challenge in the absence of antibody . We found that this immunity was mediated through the induction of specific CD8+ T cells since in vivo elimination of CD8+ cells abrogated protection . In vitro studies revealed that this Salmonella-P . berghei CS recombinant induced class I-restricted CD8+ cytotoxic T cells that are directed against the P . berghei CS peptide epitope spanning amino acids 242-253 . This is the same peptide that previously was identified as the target of cytotoxic T lymphocytes (CTL) induced by sporozoite immunization . Salmonella-P . falciparum CS recombinants were constructed that contained either the full-length CS gene or a repeatless gene consisting of CS flanking sequences . Both of these vaccines were able to induce CD8+ CTL directed against P . falciparum CS peptide 371-390, which is identical to the target of CTL induced by sporozoites and vaccinia CS recombinants . These results directly demonstrate the ability of an intracellular bacteria such as Salmonella to induce class I-restricted CD8+ CTL and illustrate the importance of CD8+ CTL in immunity to malaria.

Infect Immun, 1990 Oct, 58(10), 3183 - 6
Inflammatory effects of Salmonella typhimurium porins; Galdiero F et al.; The inflammatory activity of porins purified from Salmonella typhimurium has been investigated . Porins (0.3 to 30 micrograms) injected into the rat paw induced a dose-related edema that was not due to lipopolysaccharide contamination and did not appear to be dependent on the activation of the complement system . The edema induced by 30 micrograms of porins was comparable to that caused by 1 mg of carrageenin and was inhibited by indomethacin (5 mg/kg) and dexamethasone (0.1 mg/kg) . Porins (1 to 10 micrograms/ml) induced a concentration-related release of histamine from rat peritoneal cells . These results are discussed in the light of the possible pathogenic role of porins in infections.

Gene, 1990 Sep 28, 94(1), 29 - 35
Cloning and characterization of the asd gene of Salmonella typhimurium: use in stable maintenance of recombinant plasmids in Salmonella vaccine strains; Galan JE et al.; The asd mutants of Salmonella typhimurium have an obligate requirement for diaminopimelic acid (DAP) and will undergo lysis in environments deprived of DAP . This has allowed the development of a balanced-lethal system for the expression of heterologous antigens in vaccine strains using vectors containing the wild-type asd gene from Streptococcus mutans and asd mutant Salmonella hosts {Nakayama et al., Biotechnology 6 (1988) 693-697} . We have cloned the asd gene from S . typhimurium, characterized the gene product and used this gene to construct Asd+ expression cloning vectors . In addition we have constructed an asd cassette and a transposon derived from Tn5 that allow the rapid modification of other vectors for use with delta asd vaccine strains of S . typhimurium adding versatility to the Asd+ vector/delta asd host system of plasmid maintenance.

Biochemistry, 1990 Sep 18, 29(37), 8598 - 607
The tryptophan synthase bienzyme complex transfers indole between the alpha- and beta-sites via a 25-30 A long tunnel; Dunn MF et al.; The bacterial tryptophan synthase bienzyme complexes (with subunit composition alpha 2 beta 2) catalyze the last two steps in the biosynthesis of L-tryptophan . For L-tryptophan synthesis, indole, the common metabolite, must be transferred by some mechanism from the alpha-catalytic site to the beta-catalytic site . The X-ray structure of the Salmonella typhimurium tryptophan synthase shows the catalytic sites of each alpha-beta subunit pair are connected by a 25-30 A long tunnel {Hyde, C . C., Ahmed, S . A., Padlan, E . A., Miles, E . W., & Davies, D . R . (1988) J . Biol . Chem . 263, 17857-17871} . Since the S . typhimurium and Escherichia coli enzymes have nearly identical sequences, the E . coli enzyme must have a similar tunnel . Herein, rapid kinetic studies in combination with chemical probes that signal the bond formation step between indole (or nucleophilic indole analogues) and the alpha-aminoacrylate Schiff base intermediate, E(A-A), bound to the beta-site are used to investigate tunnel function in the E . coli enzyme . If the tunnel is the physical conduit for the transfer of indole from the alpha-site to the beta-site, then ligands that block the tunnel should also inhibit the rate at which indole and indole analogues from external solution react with E(A-A) . We have found that when D,L-alpha-glycerol 3-phosphate (GP) is bound to the alpha-site, the rate of reaction of indole and nucleophilic indole analogues with E(A-A) is strongly inhibited . These compounds appear to gain access to the beta-site via the alpha-site and the tunnel, and this access is blocked by the binding of GP to the alpha-site . However, when small nucleophiles such as hydroxylamine, hydrazine, or N-methylhydroxylamine are substituted for indole, the rate of quinonoid formation is only slightly affected by the binding of GP . Furthermore, the reactions of L-serine and L-tryptophan with alpha 2 beta 2 show only small rate effects due to the binding of GP . From these experiments, we draw the following conclusions: (1) L-Serine and L-tryptophan gain access to the beta-site of alpha 2 beta 2 directly from solution . (2) The small effects of GP on the rates of the L-serine and L-tryptophan reactions are due to GP-mediated allosteric interactions between the alpha- and beta-sites.(ABSTRACT TRUNCATED AT 400 WORDS)

J Mol Biol, 1990 Sep 5, 215(1), 41 - 51
Both genes for EF-Tu in Salmonella typhimurium are individually dispensable for growth; Hughes D; Each of the two genes encoding EF-Tu in Salmonella typhimurium has been inactivated using a mini-Mu MudJ insertion . Eleven independently isolated insertions are described, six in tufA and five in tufB . Transduction analysis shows that the inserted MudJ is 100% linked to the appropriate tuf gene . A mutant strain with electrophoretically distinguishable EF-TuA and EF-TuB was used to show, on two-dimensional gels, that the MudJ insertions result in the loss of the appropriate EF-Tu protein . Southern blotting, using cloned Escherichia coli tuf sequences as probes, shows that each MudJ insertion results in the physical breakage of the appropriate tuf gene . The degree of growth-rate impairment associated with each tuf inactivation is independent of which tuf gene is inactivated . The viability of S . typhimurium strains with either tuf gene inactive contrasts strongly with data suggesting that in the closely related bacterium E . coli, an active tufA gene is essential for growth . Finally the strains described here facilitate the analysis of phenotypes associated with individual mutant or wild-type Tus both in vivo and in vitro.

Mol Microbiol, 1990 Sep, 4(9), 1585 - 93
The pYV plasmid of Yersinia encodes a lipoprotein, YlpA, related to TraT; China B et al.; A series of lipoproteins was detected in the membrane fraction of Yersinia enterocolitica W227, a typical strain from serotype O:9 . At least two of them, YlpA and YlpB, are encoded by the pYV plasmid . The sequence of ylpA reveals the presence of a typical lipoprotein signal peptide . The mature YlpA protein would be 223 residues long with a calculated molecular weight of 23798 for the proteic moiety of the molecule . YlpA shares 88% identical residues with the TraT protein encoded by plasmid pED208, 80% identity with TraT proteins encoded by plasmids R100 and F, and 77% identity with the TraT protein encoded by the virulence plasmid of Salmonella typhimurium . The ylpA gene hybridized with the pYV plasmid of Yersinia pseudotuberculosis, suggesting that this gene is conserved among Yersinia spp . The production of YlpA is controlled by virF and only occurs at 37 degrees C in the absence of Ca2+ ions . This co-regulation with the yop genes suggests that ylpA is a virulence determinant . However, mutations in ylpA clearly affect neither the resistance to human serum nor the virulence for intravenously inoculated mice.

Sangyo Igaku, 1990 Sep, 32(5), 319 - 35
{Genotoxicity of synthetic dyes in the umu test using Salmonella typhimurium TA1535/pSK1002 (II) . Results of examination of basic dyes}; Nakamura S et al.; In the present study, SOS-inducing activity of 76 basic dyes was investigated by umu test using Salmonella typhimurium TA1535/pSK1002 under the condition of absence and presence of rat liver microsomal fraction . The test was carried out with five doses of basic dyes (400, 120, 40, 12, and 4 micrograms/ml) . The samples showing beta-galactosidase activity more than 1.5-fold over the background level were reexamined and the dose-response curves were prepared at various doses . Thereafter, samples showing beta-galactosidase activity unit more than 1.5-fold of the background level were defined as genotoxic . Among the basic dyes examined, 13 compounds induced umu gene expression . The potent genotoxic compounds without metabolic activation were Blue 40, Blue 47, Brown 14, Orange 30, Red 24, Violet 30, Violet 31, Yellow 13(h), Yellow 19, Yellow 25, Yellow 67, and Yellow 73 and in the presence of S9, Orange 47 was judged as genotoxic in addition to the aforementioned dyes . An evident dose-response relationship between the doses of the dye and umu gene expression was observed in these 13 dyes.

Mutagenesis, 1990 Sep, 5(5), 481 - 9
Bioassay-directed fractionation of 1-nitropyrene metabolites: generation of mutagrams by coupling reverse-phase HPLC with microsuspension mutagenicity assays; Lewtas J et al.; We have performed bioassay-directed fractionation of a model complex mixture (rabbit lung S9-generated metabolites of 14C-radiolabeled 1-nitropyrene) by assaying reverse-phase HPLC fractions using two microsuspension mutagenicity assays . A forward-mutation assay measuring mutation at the gpt locus (8-azaguanine resistance) in Salmonella typhimurium TM677 was performed in a total volume of 100 microliters, and a reverse-mutation assay measuring mutation at the hisD3052 allele in S . typhimurium TA98 was performed in a total volume of 200 microliters . HPLC fractions were collected every 30 s for 45 min, resulting in 90 fractions per run . The HPLC chromatogram (absorbance at 280 nm) and the 14C profile were compared to the mutagenicity profiles (mutagrams) and to the mutagenic potencies of pure metabolites studied separately . The results indicate that a fine dissection of the mutagenic fractions can be obtained by coupling HPLC to microsuspension mutagenicity assays . Differences observed between the mutagrams generated by the two bacterial strains were most likely due to metabolic (nitroreductase) differences between the two strains . This method should be generally applicable to the bioassay-directed chemical analysis of complex mixtures.

Mutagenesis, 1990 Sep, 5(5), 469 - 73
Effects of Salmonella genotypes and testing protocols on H2O2-induced mutation; Abu-Shakra A et al.; Hydrogen peroxide (H2O2) was shown to be mutagenic in a number of strains of Salmonella typhimurium . Strain SB1106p (hisC3108, hisO1242, pKM101), a newly-constructed strain carrying the histidine mutation at a UGA chain-terminating codon, was more responsive to H2O2 than TA104 or TA102, the two hisG428 strains originally developed for detecting oxidative mutagens . The largest proportional increase in revertants of strain TA104 was in the fraction of intragenic deletions . Three other strains (TA97, SB1111 and SB1106) gave unequivocal positive responses to H2O2 in both the liquid pre-incubation procedure and standard plate incorporation procedure . The response of TA100 varied among experiments, ranging from negative to a weak positive . Variations in the catalase content among the tester strains did not correlate with the relative responses obtained in the mutagenicity assays.

Mol Gen Genet, 1990 Sep, 223(2), 345 - 8
Cloning and nucleotide sequence of the Salmonella typhimurium pepM gene; Movva NR et al.; The pepM gene coding for a methionine-specific aminopeptidase was cloned from Salmonella typhimurium and its nucleotide sequence determined . The gene encoded a 264 amino acid protein that was homologous to a similar protein from Escherichia coli . The sequence of an overproducer mutant allele, pepM100, contained a single base change in the likely--35 region of the pepM promoter that increased its homology to the consensus promoter sequence . A region downstream from the pepM coding sequence contained extensive inverted repeats and was homologous to sequences found elsewhere in both Salmonella and other bacterial species.

Mol Gen Genet, 1990 Sep, 223(2), 233 - 40
Molecular cloning of the Salmonella typhimurium lep gene in Escherichia coli; van Dijl JM et al.; A system is described which enabled the selection of a heterologous lep gene, encoding signal peptidase I, in Escherichia coli . It is based on complementation of an E . coli mutant, in which the synthesis of signal peptidase I can be regulated . With this system the lep gene of Salmonella typhimurium was cloned and the nucleotide sequence was determined . The S . typhimurium lep gene encodes a protein of 324 amino acids . Expression of the gene in the E . coli mutant resulted in suppression of growth inhibition and in the restoration of processing activity under conditions where synthesis of E . coli signal peptidase I was repressed . The cloned S . typhimurium signal peptidase I had an apparent molecular weight of 36,000 daltons, which is in agreement with the calculated molecular weight of 35,782 daltons . The system described for selection of the S . typhimurium lep gene may permit the cloning and expression of other heterologous signal peptidase I genes.

Poult Sci, 1990 Sep, 69(9), 1590 - 4
Potential uses of combined halogen disinfectants in poultry processing; Smith MS et al.; Five organic N-halamine compounds (combined halogen disinfectants) were compared for their bactericidal activities against Salmonella typhimurium under controlled pH and temperature . All five compounds were effective as bactericides in demand-free buffers ranging from pH 5.0 to 9.0 and treatment temperatures from 4 to 48 C . The range of contact times necessary for a 99.9999% inactivation of viable cells was from .22 to 29 min, depending on the halogen concentration, temperature, and pH of the demand-free buffer . Two of the compounds (3-chloro-4,4-dimethyl-2-oxazolidinone and 1,3-dichloro-4,4,5,5-tetramethyl-2-imidazolidinone) were found to have considerable promise in high-temperature applications, and a third compound (1-bromo-3-chloro-4,4,5,5-tetramethyl-2-imidazolidinone) was more suitable for low-temperature treatments.

J Appl Bacteriol, 1990 Sep, 69(3), 373 - 83
Heat shock protein synthesis and thermotolerance in Salmonella typhimurium; Mackey BM et al.; The resistance of stationary phase Salmonella typhimurium to heating at 55 degrees C was greater in cells grown in nutritionally rich than in minimal media, but in all media tested resistance was enhanced by exposing cells to a primary heat shock at 48 degrees C . Chloramphenicol reduced the acquisition of thermotolerance in all media but did not completely prevent it in any . The onset of thermotolerance was accompanied by increased synthesis of major heat shock proteins of molecular weight about 83, 72, 64 and 25 kDa . When cells were shifted from 48 degrees C to 37 degrees C, however, thermotolerance was rapidly lost with no corresponding decrease in the levels of these proteins . There is thus no direct relationship between thermotolerance and the cellular content of the major heat shock proteins . One minor protein of molecular weight about 34 kDa disappeared rapidly following a temperature down-shift . Its presence in the cell was thus correlated with the thermotolerant state.

J Antimicrob Chemother, 1990 Sep, 26 Suppl A, 53 - 7
Multiresistant Salmonella typhimurium systemic infection in Rwanda . Clinical features and treatment with cefotaxime; Lepage P et al.; Children with multiresistant Salmonella typhimurium (MRST) systemic infections, in total 246, were diagnosed during the study period . Of these, 220 had MRST without metastatic focal infections and 26 had metastatic focal infections (including 12 patients with meningitis) . The median age of the children was 10 months . Diarrhoeal disease, measles and severe malnutrition were the most frequent causes of admission . Fever was found in 99% and diarrhoea in 72% of the patients, with respiratory symptoms in 72% . In 199 (81%) of the patients, the MRST infection was considered to be hospital-acquired . Of the 246 children, 159 were treated with cefotaxime . In this group, 16 of 152 patients died (10.5%) . However, of the 87 children who did not receive cefotaxime, 64 died (74%) . Relapses occurred in 4% of the patients with bacteraemia treated with cefotaxime . Our study confirms the high efficiency of cefotaxime in treating severe systemic infections with MRST.

Gene, 1990 Sep 1, 93(1), 147 - 50
Nucleotide sequence of mkaD, a virulence-associated gene of Salmonella typhimurium containing variable and constant regions; Taira S et al.; We have identified the nucleotide (nt) sequence of mkaD, a virulence-associated gene of the Salmonella typhimurium virulence plasmid, pEX102 . The gene shows 98% homology on nt sequence level to mkfA, a corresponding gene of the S . typhimurium virulence plasmid pIP1350 . The few nt changes, however, caused more extensive changes on the amino-acid level . The differences between mkaD and mkfA were clustered in distinct variable regions rather than being randomly scattered along the sequence . A third salmonellar virulence plasmid, pLT2, contained an mkaD gene identical to that of pEX102 . Our observation suggests that the conserved virulence determinant on the plasmids of Salmonellae may contain different alleles of the same gene.

Proc Natl Acad Sci U S A, 1990 Sep, 87(18), 7076 - 9
Structure-function studies on Escherichia coli MetR protein, a putative prokaryotic leucine zipper protein; Maxon ME et al.; The Escherichia coli metR gene has been sequenced . The sequence predicts a protein of 317 amino acids and a calculated molecular weight of 35,628 . This is about 15% larger than the protein from Salmonella typhimurium reported previously {Plamann, L.S . & Stauffer, G.V . (1987) J . Bacteriol . 169, 3932-3937} . The protein is a homodimer and contains a leucine zipper motif characteristic of many eukaryotic DNA-binding proteins . Replacement of two of the leucines in the leucine zipper region of the MetR protein, or substitution of proline for one of the leucines, results in loss of biological activity of the protein . In addition, truncation studies have identified a region on MetR that may be involved in the homocysteine activation of metE expression.

Carcinogenesis, 1990 Sep, 11(9), 1503 - 7
Genotoxicity of methylglyoxal: cytogenetic damage in human lymphocytes in vitro and in intestinal cells of mice; Migliore L et al.; The mutagenic activity of methylglyoxal (MG) was assayed in vitro in human lymphocytes {induction of chromosomal aberrations (CAs), sister chromatid exchanges (SCEs) and micronuclei} both in the presence and in the absence of metabolic activation (S9 mix) . The Ames/microsome test was performed with the Salmonella typhimurium strains considered more responsive (TA102 and TA104) . Positive results were obtained for all the genetic endpoints analysed . In human lymphocytes the activity of MG is decreased by the presence of S9 mix . In the in vivo studies, the metaphase analysis in the ileum and duodenum cells of mice treated per os with MG (400 and 600 mg/kg body wt) gave negative results for CA induction, while only a weak increase of SCE in duodenum cells at the higher dose was obtained . Dimethylhydrazine (25 mg/kg body wt), as positive control, was clearly active in inducing both CAs and SCEs in the same intestinal tissues.

Carcinogenesis, 1990 Sep, 11(9), 1451 - 60
Metabolic activation of 9-hydroxymethyl-10-methylanthracene and 1-hydroxymethylpyrene to electrophilic, mutagenic and tumorigenic sulfuric acid esters by rat hepatic sulfotransferase activity; Surh YJ et al.; Our previous studies on 7-hydroxymethyl-12-methylbenz{a}anthracene and 6-hydroxymethylbenzo{a}pyrene showed that cytosolic sulfotransferase activity plays a major role in the formation of hepatic benzylic DNA and RNA adducts by these carcinogens in rats . In the present study, we found similar sulfotransferase activity in rat liver cytosol which activates 9-hydroxymethyl-10-methylanthracene (HMA) and 1-hydroxymethylpyrene (HMP) to electrophilic sulfuric acid ester metabolites . Thus, incubation of these nonbay region hydrocarbons with calf thymus DNA in the presence of liver cytosol fortified with the sulfo-group donor, 3'-phosphoadenosine-5'-phosphosulfate (PAPS) produced benzylic DNA adducts that were chromatographically identical to those obtained by the reactions of the corresponding sulfuric acid esters with deoxyguanosine and deoxyadenosine . These adducts were also produced in the livers of infant rats injected i.p . with 0.25 mumol/g body wt of HMA or HMP . Administration of comparable doses of 9-sulfooxymethyl-10-methylanthracene (SMA) and 1-sulfooxymethylpyrene (SMP) resulted in much higher levels of hepatic benzylic DNA adducts than did the parent hydroxymethyl hydrocarbons . Both HMA and HMP induced His+ revertants in Salmonella typhimurium TA98 when preincubated with these bacteria in the presence of rat liver cytosol and PAPS . This sulfotransferase-mediated mutagenicity of HMA and HMP was reduced by dehydroepiandrosterone, an inhibitor of hepatic sulfotransferase activity for these hydrocarbons . SMA and SMP were directly mutagenic and their intrinsic bacterial mutagenicity was inhibited by glutathione (GSH) and GSH-S-transferase activity . Chloride ion at physiological concentrations enhanced the bacterial mutagenicity of SMA through the formation of 9-chloromethyl-10-methylanthracene as previously observed for SMP by Henschler et al . In contrast to the higher mutagenicity of 1-chloromethylpyrene (CMP) than SMP in bacteria, CMP formed smaller amounts of hepatic benzylic DNA adducts in rats than the sulfuric acid ester . SMA and SMP were weak skin tumor initiators in the mouse, but they were more active than HMA and HMP in this regard.

J Bacteriol, 1990 Sep, 172(9), 5459 - 69
Physiological consequences of the complete loss of phosphoryl-transfer proteins HPr and FPr of the phosphoenolpyruvate:sugar phosphotransferase system and analysis of fructose (fru) operon expression in Salmonella typhimurium; Feldheim DA et al.; Mutants of Salmonella typhimurium defective in the proteins of the fructose operon {fruB(MH)KA}, the fructose repressor (fruR), the energy-coupling enzymes of the phosphoenolpyruvate:sugar phosphotransferase system (PTS) (ptsH and ptsI), and the proteins of cyclic AMP action (cya and crp) were analyzed for their effects on cellular physiological processes and expression of the fructose operon . The fru operon consists of three structural genes: fruB(MH), which encodes the enzyme IIIFru-modulator-FPr tridomain fusion protein of the PTS; fruK, which encodes fructose-1-phosphate kinase; and fruA, which encodes enzyme IIFru of the PTS . Among the mutants analyzed were Tn10 insertion mutants and lacZ transcriptional fusion mutants . It was found that whereas a fruR::Tn10 insertion mutant, several fruB(MH)::Mu dJ and fruK::Mu dJ fusion mutants, and several ptsHI deletion mutants expressed the fru operon and beta-galactosidase at high constitutive levels, ptsH point mutants and fruA::Mu dJ fusion mutants retained inducibility . Inclusion of the wild-type fru operon in trans did not restore fructose-inducible beta-galactosidase expression in the fru::Mu dJ fusion mutants . cya and crp mutants exhibited reduced basal activities of all fru regulon enzymes, but inducibility was not impaired . Surprisingly, fruB::Mu dJ crp or cya double mutants showed over 10-fold inducibility of the depressed beta-galactosidase activity upon addition of fructose, even though this activity in the fruB::Mu dJ fusion mutants that contained the wild-type cya and crp alleles was only slightly inducible . By contrast, beta-galactosidase activity in a fruK::Mu dJ fusion mutant, which was similarly depressed by introduction of a crp or cya mutation, remained constitutive . Other experiments indicated that sugar uptake via the PTS can utilize either FPr-P or HPr-P as the phosphoryl donor, but that FPr is preferred for fructose uptake whereas HPr is preferred for uptake of the other sugars . Double mutants lacking both proteins were negative for the utilization of all sugar substrates of the PTS, were negative for the utilization of several gluconeogenic carbon sources, exhibited greatly reduced adenylate cyclase activity, and were largely nonmotile . These phenotypic properties are more extreme than those observed for tight ptsH and ptsI mutants, including mutants deleted for these genes . A biochemical explanation for this fact is proposed.

J Bacteriol, 1990 Sep, 172(9), 5416 - 24
A locus affecting nucleoid segregation in Salmonella typhimurium; Schmid MB; Thirteen temperature-sensitive lethal mutations of Salmonella typhimurium map near metC at 65 min and form the clmF (conditional lethal mutation) locus . The mutations in this region were ordered by three-point transduction crosses . After a shift to the nonpermissive temperature, many of these clmF mutants failed to complete the segregation of nucleoids into daughter cells; daughter nucleoids appeared incompletely separated and asymmetrically positioned within cells . Some clmF mutants showed instability of F' episomes at permissive growth temperatures yet showed no detectable defect with smaller multicopy plasmids such as pSC101 or pBR322 . In addition, many of the clmF mutants rapidly lost viability yet continued DNA replication at the nonpermissive temperature . These results suggest that the clmF locus encodes at least one indispensable gene product that is required for faithful partitioning of the bacterial nucleoid and F-plasmid replicons.

J Bacteriol, 1990 Sep, 172(9), 5266 - 77
Isolation of the replication and partitioning regions of the Salmonella typhimurium virulence plasmid and stabilization of heterologous replicons; Tinge SA et al.; Although the virulence plasmid of Salmonella typhimurium has a copy number of one to two per chromosome, plasmid-free segregants are produced at a rate less than 10(-7) per cell per generation . Three regions appear to be involved in the maintenance of this virulence plasmid . The first two, repB and repC, are functional replicons hybridizing with IncFII and IncFI plasmids, respectively, neither exhibiting the segregational stability of the parent virulence plasmid . The third region, par, cloned as a 3.9-kilobase Sau3A fragment, is not a functional replicon but exhibits incompatibility with the virulence plasmid . Subsequent tests revealed the ability of this 3.9-kilobase par insert to increase the stability of pACYC184 in S . typhimurium from less than 34% to 99% plasmid-containing cells after 50 generations . In addition, the par region increased the stability of oriC, R388, and repC replicons in both S . typhimurium and Escherichia coli hosts . The par region encodes 44,000- and 40,000-molecular-weight proteins essential for the Par+ phenotype but not for the Inc+ phenotype . Although actual sequestering of plasmids within the cell was not demonstrated, all results indicate that the par region described is an actual partitioning locus, similar in organization to those described for plasmids F, P1, and NR1.

J Bacteriol, 1990 Sep, 172(9), 5089 - 96
Effect of growth temperature on folding of carbamoylphosphate synthetases of Salmonella typhimurium and a cold-sensitive derivative; Han BD et al.; The properties of homogeneous preparations of carbamoylphosphate synthetase (CPSase) from wild-type Salmonella typhimurium and a cold-sensitive derivative grown at different growth temperatures were examined . For the cold-sensitive mutant, the affinity for glutamine of the form of CPSase synthesized at 20 degrees C was lower than that of the form of the enzyme synthesized at 37 degrees C, regardless of the assay temperature . Thus, the cold sensitivity of the mutant reflects an effect of temperature on the synthesis of the enzyme rather than the activity of the folded enzyme . The two forms also differed in sensitivities to polyclonal antibodies as well as denaturational enthalpies . The combined results support the hypothesis that carAB mutations conferring cold sensitivity identify amino acid residues that are critical in the folding of CPSase . Quite unexpectedly, certain kinetic properties of cloned parent CPSase were also dependent on the growth temperature, although to a much lesser extent than those of the cold-sensitive mutant . The specific activity of wild-type CPSase synthesized at 15 degrees C was 60% of that synthesized at 37 degrees C . Further, CPSase synthesized at 15 degrees C was less thermostable than the enzyme synthesized at 37 degrees C; the difference in stability (delta G) is estimated to be 4,500 cal mol-1 . Thus, variation of temperature within the physiological range for growth influences the folding and consequently the properties of CPSase from wild-type S . typhimurium.

J Bacteriol, 1990 Sep, 172(9), 4979 - 87
Structural characterization of the Salmonella typhimurium LT2 umu operon; Thomas SM et al.; The umuDC operon of Escherichia coli encodes functions required for mutagenesis induced by radiation and a wide variety of chemicals . The closely related organism Salmonella typhimurium is markedly less mutable than E . coli, but a umu homolog has recently been identified and cloned from the LT2 subline . In this study the nucleotide sequence and structure of the S . typhimurium LT2 umu operon have been determined and its gene products have been identified so that the molecular basis of umu activity might be understood more fully . S . typhimurium LT2 umu consists of a smaller 417-base-pair (bp) umuD gene ending 2 bp upstream of a larger 1,266-bp umuC gene . The only apparent structural difference between the two operons is the lack of gene overlap . An SOS box identical to that found in E . coli is present in the promoter region upstream of umuD . The calculated molecular masses of the umuD and umuC gene products were 15.3 and 47.8 kilodaltons, respectively, which agree with figures determined by transpositional disruption and maxicell analysis . The S . typhimurium and E . coli umuD sequences were 68% homologous and encoded products with 71% amino acid identity; the umuC sequences were 71% homologous and encoded products with 83% amino acid identity . Furthermore, the potential UmuD cleavage site and associated catalytic sites could be identified . Thus the very different mutagenic responses of S . typhimurium LT2 and E . coli cannot be accounted for by gross differences in operon structure or gene products . Rather, the ability of the cloned S . typhimurium umuD gene to give stronger complementation of E . coli umuD77 mutants in the absence of a functional umuC gene suggests that Salmonella UmuC protein normally constrains UmuD protein activity.

J Bacteriol, 1990 Sep, 172(9), 4783 - 9
Adaptation of Salmonella typhimurium mutants containing uncoupled enzyme IIGlc to glucose-limited conditions; Ruijter GJ et al.; Uncoupled enzyme IIGlc of the phosphoenolpyruvate (PEP):glucose phosphotransferase system (PTS) in Salmonella typhimurium is able to catalyze glucose transport in the absence of PEP-dependent phosphorylation . As a result of the ptsG mutation, the apparent Km of the system for glucose transport is increased about 1,000-fold (approximately 18 mM) compared with wild-type PTS-mediated glucose transport . An S . typhimurium mutant containing uncoupled enzyme IIGlc as the sole system for glucose uptake was grown in glucose-limited chemostat cultures . Selective pressure during growth in the chemostat resulted in adaptation to the glucose-limiting conditions in two different ways . At first, mutations appeared that led to a decrease in Km value of uncoupled enzyme IIGlc . These results suggested that uncoupled enzyme IIGlc had significant control on the growth rate under glucose-limiting conditions . More efficient glucose uptake enabled a mutant to outgrow its parent and caused a decrease in the steady-state glucose concentration in the chemostat . At very low glucose concentrations (10 microM), mutants arose that contained a constitutively synthesized methyl-beta-galactoside permease . Apparently, further changes in the uncoupled enzyme IIGlc did not lead to a substantial increase in growth rate at very low glucose concentrations.

Mutat Res, 1990 Sep, 245(1), 15 - 22
The mutagenic modulating effect of p-phenylenediamine on the oxidation of o- or m-phenylenediamine with hydrogen peroxide in the Salmonella test; Watanabe T et al.; The mutagenicity of o- and m-phenylenediamine (PD) was remarkedly enhanced by oxidation; their major mutagenic oxidation products were 2,3- and 2,7-diaminophenazine, respectively . In order to evaluate the modulation effect of p-PD on the oxidation of m- or o-PD, p-PD and mixtures of m- and p-PD (m-PD/p-PD) and o- and p-PD (o-PD/p-PD) were oxidized with hydrogen peroxide and their mutagenicity was tested in Salmonella typhimurium TA98 in the presence or absence of a mammalian metabolic activation system (S9 mix) . The H2O2-oxidized m-PD/p-PD and o-PD/p-PD were potent mutagens with S9 mix, whereas H2O2-oxidized p-PD was slightly mutagenic . The major mutagenic oxidation products of m-PD/p-PD and o-PD/p-PD were identified as 2,7- and 2,3-diaminophenazine, respectively, by TLC and HPLC . 2,8-Diaminophenazine was also found as a reaction product in oxidized m-PD/p-PD, and it was weakly mutagenic . The mutagenic potency of oxidized m-PD/p-PD or o-PD/p-PD was lower than that of singly oxidized m-PD or o-PD . The yield of 2,7- and 2,3-diaminophenazine was obviously decreased with increases in p-PD, and it was concluded that the declined mutagenic potency of oxidized m-PD/p-PD or o-PD/p-PD was due to the decrease in diaminophenazines . But the formation of diaminophenazines was not completely inhibited by the addition of a 9-fold molar ratio of p-PD to m-PD or o-PD, 8.6 nmole of 2,7-diaminophenazine and 1882.4 nmole of 2,3-diaminophenazine were formed from 1 mmole of m-PD and o-PD, respectively.

Mutat Res, 1990 Sep, 242(1), 9 - 15
Mutagenic compounds in wood-chip drying fumes; Kurttio P et al.; The mutagenicity of fumes from the heating of freshly cut spruce and birch chips was measured with Salmonella typhimurium strains TA98, TA100 and TA102 . The bacteria were exposed directly and indirectly to the fumes . Wood chips were also extracted with solvents . No mutagenicity was found in wood extracts or the fume samples measured indirectly . The results from the direct exposure experiments indicate, however, that drying spruce and birch at 170 degrees C emits mutagenic compounds, which are short-lived and/or volatile . One of the mutagenic compounds of the fumes is probably 3-carene . These results are consistent with previous epidemiological findings, which suggest that these fumes are carcinogenic.

J Bacteriol, 1990 Sep, 172(9), 5402 - 7
Subunit-specific phenotypes of Salmonella typhimurium HU mutants; Hillyard DR et al.; Salmonella hupA and hupB mutants were studied to determine the reasons for the high degree of conservation in HU structure in bacteria . We found one HU-1-specific effect; the F'128 plasmid was 25-fold less stable in hupB compared with hupA or wild-type cells . F' plasmids were 120-fold more unstable in hupA hupB double mutants compared with wild-type cells, and the double mutant also had a significant alteration in plasmid DNA structure . pBR322 DNA isolated from hupA hupB strains was deficient in supercoiling by 10 to 15% compared with wild-type cells, and the topoisomer distribution was significantly more heterogeneous than in wild-type or single-mutant strains . Other systems altered by HU inactivation included flagellar phase variation and phage Mu transposition . However, Mu transposition rates were only about fourfold lower in Salmonella HU double mutants . One reason that Salmonella HU double mutants may be less defective for Mu transposition than E . coli is the synthesis in double mutants of a new, small, basic heat-stable protein, which might partially compensate for the loss of HU . The results indicate that although either HU-1 or HU-2 subunit alone may accommodate the cellular need for general chromosomal organization, the selective pressure to conserve HU-1 and HU-2 structure during evolution could involve specialized roles of the individual subunits.

J Bacteriol, 1990 Sep, 172(9), 5312 - 25
Genetic analysis of lipopolysaccharide core biosynthesis by Escherichia coli K-12: insertion mutagenesis of the rfa locus; Austin EA et al.; Tn10 insertions were selected on the basis of resistance to the lipopolysaccharide (LPS)-specific bacteriophage U3 . The majority of these were located in a 2-kilobase region within the rfa locus, a gene cluster of about 18 kb that contains genes for LPS core biosynthesis . The rfa::Tn10 insertions all exhibited a deep rough phenotype that included hypersensitivity to hydrophobic antibiotics, a reduction in major outer membrane proteins, and production of truncated LPS . These mutations were complemented by a Clarke-Carbon plasmid known to complement rfa mutations of Salmonella typhimurium, and analysis of the insert from this plasmid showed that it contained genes for at least six polypeptides which appear to be arranged in the form of a complex operon . Defects in two of these genes were specifically implicated as the cause of the deep rough phenotype . One of these appeared to be rfaG, which encodes a function required for attachment of the first glucose residue to the heptose region of the core . The other gene did not appear to be directly involved in determination of the sugar composition of the core . We speculate that the product of this gene is involved in the attachment of phosphate or phosphorylethanolamine to the core and that it is the lack of one of these substituents which results in the deep rough phenotype.

Mutat Res, 1990 Sep, 232(1), 99 - 104
Studies on Tn10 transposition and excision in DNA-repair mutants of Salmonella typhimurium; Lorenzo C et al.; Transposition of Tn10 in polA, recA, uvrB, mutH and uvrD mutants of Salmonella typhimurium was studied by a mating-out assay mediated by R plasmid pKM101 . A decrease in transposition frequency was observed with polA, recA and uvrD mutants; uvrB and mutH mutants showed frequencies somewhat higher than control values . No effect of dimethyl sulfoxide, sodium acetate or nitrofurazone on Tn10 transposition was observed with this assay . Precise excision of Tn10 from srl202::Tn10 in these DNA-repair mutants was also studied . An increase in excision frequency of about 20 or 150 times in 2 different polA mutants, and a smaller increase, of about 2 or 15 times over control values, was detected in mutH and uvrD mutants, respectively.

Infect Immun, 1990 Sep, 58(9), 3084 - 92
Conservation of Salmonella typhimurium virulence plasmid maintenance regions among Salmonella serovars as a basis for plasmid curing; Tinge SA et al.; The association of large plasmids with virulence in invasive Salmonella serovars has led to a number of studies designed to uncover the role of these plasmids in virulence . This study addresses two aspects of virulence-associated plasmids . The first is the distribution of the replication and maintenance regions among the plasmids of different Salmonella serovars, and the second is the use of the conserved virulence plasmid par region to provide a rapid method for eliminating the virulence plasmids specifically . Colony blots revealed that the par and repB regions of the S . typhimurium virulence plasmid hybridized with 80% of the isolates of S . choleraesuis, S . dublin, S . enteritidis, S . gallinarum, S . pullorum, and S . typhimurium, while the repC region was not detected in any of the isolates of S . dublin, S . gallinarum, or S . pullorum . None of these maintenance regions was found in any of the 30 additional serovars tested . The large plasmids of those serovars that hybridized with par were labeled with a Kmr insert within parA via P22HTint or P1L4 transduction, which destabilized the plasmids and allowed the rapid isolation of plasmid-free derivatives for all of the serovars, except for S . dublin, which exhibited weak homology with par.

Protein Expr Purif, 1990 Sep, 1(1), 70 - 6
A rapid purification procedure and computer-assisted sulfide ion selective electrode assay for O-acetylserine sulfhydrylase from Salmonella typhimurium; Hara S et al.; An improved method for purifying O-acetylserine sulfhydrylase from Salmonella typhimurium is described as well as a new computer-controlled assay making use of the sulfide ion selective electrode . The purification method uses gradient elution from Q-Sepharose Fast Flow and phenyl-Sepharose columns to give 75 mg (50% yield) of the enzyme starting from 300 g of starting material in 3 days . The sulfide electrode assay makes use of sulfide and calomel electrodes attached to a signal buffer which serves as an impedance match . The output of the signal buffer is linked in parallel to a strip chart recorder and a Keithley Model 575 data acquisition and control system . The system 575 is interfaced to a Packard-Bell AT computer . In addition, two BASIC computer programs have been written to convert potential measured by the electrode to sulfide concentration and to convert the time course data to rates.

Plant Mol Biol, 1990 Sep, 15(3), 421 - 35
Analysis of chloroplast promoters using bidirectional transcription vectors; Rogers SA et al.; Spinach chloroplast RNA polymerase has been shown to efficiently terminate transcription at the threonine attenuator (thra) from Escherichia coli . In this study, efficient transcription termination by the chloroplast RNA polymerase was observed at a second prokaryotic terminator, the histidine attenuator (hisa) from Salmonella typhimurium . Termination occurred regardless of the orientation of either attenuator . In higher-plant chloroplast DNA, the genes for the beta subunit of the ATPase (atpB) and the large subunit of ribulose 1,5-bisphosphate carboxylase/oxygenase (rbcL) are adjacent and divergently transcribed . Bidirectional transcription vectors, containing the histidine and threonine terminators, were constructed to analyze the divergently oriented atpB and rbcL promotors . One plasmid construction, pRTT7, contained two tandem copies of the threonine attenuator (pRTT7) . Two additional constructs, pRHT1 and pRHT2, each contained oppositely oriented copies of thra and hisa . A DNA fragment containing the rbcL and atpB promoters was inserted between the two terminators present in the pRTT7, pRHT1, and pRHT2 plasmids . Transcription of these recombinant DNAs by spinach chloroplast RNA polymerase resulted in discretely sized rbcL and atpB transcripts . In addition, these bidirectional transcription vectors were used to identify previously uncharacterized chloroplast promoters.

Appl Environ Microbiol, 1990 Sep, 56(9), 2748 - 54
Expression of a Neurospora crassa metallothionein and its variants in Escherichia coli; Romeyer FM et al.; The Neurospora crassa metallothionein (NC) synthesis gene was cloned and expressed in Escherichia coli in two different expression vectors (pING2 and pUA7), both under the regulation of the Salmonella typhimurium arabinose operon . Upon induction with arabinose, the pING2-NC vector expressed as inclusion body-localized AraB'::NC fusion protein of 21 kilodaltons . The pUA7-NC vector expressed a 5.3-kilodalton Lpp::NC fusion protein anchored to the outer membrane of the cell . Cells expressing the NC fusion proteins accumulated Cd2+ and Cu+ (between 2.3- and 11-fold) compared with nonexpressing cells . To generate novel forms of metal-binding peptides, a set of specific mutant genes for N . crassa NC was designed in which each cysteine residue was replaced with a subset of amino acids implicated in peptide-metal coordination (Asn, Asp, His, Lys, or Tyr residues) . These mutant NC sequences were cloned into the two vectors and expressed in E . coli . One of the mutant proteins (containing His residues) showed accumulation of Cd2+ and Cu+ (threefold) from a mixture of 16 heavy metals species . None of the other heavy metals present in the culture was accumulated.

FEMS Microbiol Immunol, 1990 Sep, 2(2), 89 - 96
Roles of the complement receptor type 1 (CR1) and type 3 (CR3) on phagocytosis and subsequent phagosome-lysosome fusion in Salmonella-infected murine macrophages; Ishibashi Y et al.; The receptors involved in the recognition of Salmonella typhimurium and S . typhi by murine macrophages were identified, and their relevance to phagosome-lysosome fusion was also investigated . Phagocytosis of S . typhimurium by murine macrophages was dependent on the opsonization with normal fresh serum, although the opsonin had no triggering activity in phagosome-lysosome fusion . In contrast, the opsonization of S . typhi with normal fresh serum efficiently triggered both phagocytosis and following phagosome-lysosome fusion . Anti-murine CR1 antibody suppressed phagocytosis of S . typhimurium by 36%, whereas anti-CR3 antibody, mannan, and advanced glycosylation endproducts (AGE)-BSA all failed to prevent phagocytosis of S . typhimurium, suggesting that CR1 may only contribute to the recognition of S . typhimurium and may possibly play a minor role . Other receptors involved may also influence the outcome of phagocytosis in terms of phagosome-lysosome fusion . In the case of S . typhi, only anti-CR3 antibody significantly inhibited not only phagocytosis of S . typhi but also following phagosome-lysosome fusion . Treatment with K76COONa, an inhibitor of C3bINA (I factor), resulted in a marked inhibition of phagosome-lysosome fusion in S . typhi-infected macrophages, although no significant inhibition was observed on phagocytosis of S . typhi . These results suggest that S . typhimurium and S . typhi may be recognized at least in part by CR1 and CR3, respectively, and that the recognition by CR3 but not CR1 is functionally associated with subsequent phagosome-lysosome fusion in murine macrophages.

J Bacteriol, 1990 Sep, 172(9), 4964 - 78
Sequence analysis and mapping of the Salmonella typhimurium LT2 umuDC operon; Smith CM et al.; In Escherichia coli, efficient mutagenesis by UV requires the umuDC operon . A deficiency in umuDC activity is believed to be responsible for the relatively weak UV mutability of Salmonella typhimurium LT2 compared with that of E . coli . To begin evaluating this hypothesis and the evolutionary relationships among umuDC-related sequences, we cloned and sequenced the S . typhimurium umuDC operon . S . typhimurium umuDC restored mutability to umuD and umuC mutants of E . coli . DNA sequence analysis of 2,497 base pairs (bp) identified two nonoverlapping open reading frames spanning 1,691 bp that were were 67 and 72% identical at the nucleotide sequence level to the umuD and umuC sequences, respectively, from E . coli . The sequences encoded proteins whose deduced primary structures were 73 and 84% identical to the E . coli umuD and umuC gene products, respectively . The two bacterial umuDC sequences were more similar to each other than to mucAB, a plasmid-borne umuDC homolog . The umuD product retained the Cys-24--Gly-25, Ser-60, and Lys-97 amino acid residues believed to be critical for RecA-mediated proteolytic activation of UmuD . The presence of a LexA box 17 bp upstream from the UmuD initiation codon suggests that this operon is a member of an SOS regulon . Mu d-P22 inserts were used to locate the S . typhimurium umuDC operon to a region between 35.9 and 40 min on the S . typhimurium chromosome . In E . coli, umuDC is located at 26 min . The umuDC locus in S . typhimurium thus appears to be near one end of a chromosomal inversion that distinguishes gene order in the 25- to 35-min regions of the E . coli and S . typhimurium chromosomes . It is likely, therefore, that the umuDC operon was present in a common ancestor before S . typhimurium and E . coli diverged approximately 150 million years ago . These results provide new information for investigating the structure, function, and evolutionary origins of umuDC and for exploring the genetic basis for the mutability differences between S . typhimurium and E . coli.

Chem Res Toxicol, 1990 Sep-Oct, 3(5), 458 - 66
Metabolic activation of 1,2-dibromo-3-chloropropane to mutagenic metabolites: detection and mechanism of formation of (Z)- and (E)-2-chloro-3-(bromomethyl)oxirane; Pearson PG et al.; 1,2-Dibromo-3-chloropropane (DBCP), a haloalkane nematocide and soil fumigant, is metabolically activated to chemically reactive species that are direct-acting mutagens in a Salmonella typhimurium TA 100 test system . Studies in vitro with rat liver microsomes indicated that oxidation at carbon 3 resulted in the formation of an unstable gem-chlorohydrin that rearranged with elimination of hydrogen bromide to form (Z)-2-chloro-3-(bromomethyl)oxirane {(Z)-CBPO} and (E)-2-chloro-3-(bromomethyl)oxirane {(E)-CBPO} . Gas chromatography-mass spectrometry (GC-MS) with positive ion chemical ionization (CI) was employed to identify (Z)-CBPO and (E)-CBPO by comparison of characteristic fragment ions in their CI mass spectra with those observed for authentic standards . Quantitative GC-MS methodology was exploited to quantitate the rate of formation of (Z)-CBPO and (E)-CBPO from DBCP and analogues of DBCP specifically deuterated at carbon 1 and carbon 3 . The rate of formation of Z- and E-isomers of CBPO was 31 and 33 pmol/(min.mg of protein), respectively, from DBCP; substitution with deuterium at carbon 1 increased the rate of epoxide formation by 50%, whereas CBPO formation could not be detected from a substrate labeled with deuterium at carbon 3 . Both epoxides were directly acting mutagens to S . typhimurium TA 100 . (Z)-CBPO caused approximately twice as many his+ revertants/nmol compared to (E)-CBPO . Oxidation at carbon 2 of DBCP resulted in the formation of a bifunctional alkylating agent, 1-bromo-3-chloroacetone, presumably via the intermediacy of an unstable gem-bromohydrin.(ABSTRACT TRUNCATED AT 250 WORDS)

FEMS Microbiol Immunol, 1990 Sep, 2(2), 75 - 82
Effect of gamma-interferon on phagosome-lysosome fusion in Salmonella typhimurium-infected murine macrophages; Ishibashi Y et al.; Effect of recombinant gamma-interferon (rIFN-gamma) on phagosome-lysosome fusion in Salmonella typhimurium-infected murine macrophages was examined . rIFN-gamma enhanced phagosome-lysosome fusion in macrophages infected with S . typhimurium in a dose-dependent manner, and over a range of 10(2) to 10(3) U/ml of rIFN-gamma exhibited maximum phagosome-lysosome fusion, although phagocytosis was slightly decreased . The enhancement of phagosome-lysosome fusion occurred greater than 3 h post-treatment with rIFN-gamma . Furthermore, the macrophage activation for phagosome-lysosome fusion was found to persist for 4 days even when rIFN-gamma had been removed . These results demonstrate that IFN-gamma may serve as a mediator for the activation of phagosome-lysosome fusion in murine macrophages.

Carcinogenesis, 1990 Sep, 11(9), 1653 - 8
Contribution of DNA methylation and benzylation to N-nitroso-N-benzyl-methylamine-induced mutagenesis in bacteria: effects of rat liver cytochrome P450 isozymes and glutathione transferases; Lin DX et al.; The mutagenicity of N-nitroso-N-benzyl-methylamine (NBzMA), N-benzyl-N-nitrosourea (BzNU) and N-methyl-N-nitrosourea (MNU) in Salmonella typhimurium strains was investigated . BzNU selectively mutated TA100 strain as compared to TA1535, whereas MNU showed an inverse strain response, an effect probably related to the fact that benzylation of DNA is a stronger inducer of SOS DNA repair than methylation, as indicated by the higher activity of BzNU in the SOS chromotest . Benzylation of bacterial DNA by NBzMA, as deduced from the differential strain responsiveness, contributed predominantly to its mutagenicity in the presence of liver preparation from untreated, Aroclor- or ethanol-treated rats . Since benzyl alcohol, a metabolite of NBzMA, was not mutagenic in S . typhimurium, it appears that benzyl carbonium cations responsible for the mutagenicity of NBzMA in TA100 are formed via cytochrome P450-mediated hydroxylation of the methyl group . Neither ferric-EDTA nor desferrioxamine altered the mutagenicity of NBzMA, suggesting that activation occurs mainly within the catalytic site of P450 . Experiments with isozyme-specific monoclonal antibodies showed that P450IIE1 did not contribute to N-demethylation of NBzMA at either low or high substrate concentrations and that P450IA contributed only weakly . Debenzylation was catalysed predominantly by P450IA at high NBzMA concentration . Antibodies against rat liver P450IIB enhanced NBzMA mutagenicity in S . typhimurium TA1535 strain up to 17-fold at low substrate concentration, but were without effect at high concentration . In liquid incubation assays, a 100% GSH-dependent reduction of NBzMA mutagenicity was found with liver S9 from untreated Wistar rats . The reducing effect of GSH was less pronounced in the presence of liver S9 from BDVI or Fischer 344 rats.

Carcinogenesis, 1990 Sep, 11(9), 1635 - 9
Sulfite enhancement of diolepoxide mutagenicity: the role of altered glutathione metabolism; Reed GA et al.; Sulfur dioxide is a cocarcinogen for benzo{a}pyrene in the respiratory tract of rats and hamsters . Sulfur dioxide exists under physiological conditions as the sulfite ion . Sulfite enhances the mutagenic potency of (+-)-7r,8t-dihydroxy-9t,-10t- epoxy-7,8,9,10-tetrahydrobenzo{a}pyrene (anti-BPDE) and 7r,8t-dihydroxy-9c10c-epoxy-7,8,9,10-tetrahydrobenzo{a}py ren e (syn-BPDE) in Salmonella typhimurium strains TA98 and TA100 . This enhancement of diolepoxide mutagenicity is observed with sulfite concentrations between 1 and 20 mM, and the concentration dependence is identical for the two diolepoxides . Half-maximal enhancement of mutagenicity occurs at approximately 5 mM sulfite . Sulfite is neither toxic nor mutagenic to the bacteria under these conditions . The enhancement of diolepoxide mutagenicity requires that the bacteria be exposed to sulfite prior to the addition of the diolepoxide . Simultaneous addition of sulfite and diolepoxide significantly decreases the enhancing effect, and addition 15 min after the diolepoxide virtually abolishes the effect . This is consistent with sulfite serving to increase the efficiency of processes leading to DNA modification by the diolepoxides, rather than some effect subsequent to DNA adduct formation . Direct evidence for this hypothesis was provided by determining the effect of sulfite on mutagenicity and DNA binding in TA98 using {3H}anti-BPDE . Exposure of the bacteria to 10 mM sulfite for 5 min prior to the addition of the labeled mutagen led to as much as 170% increase in DNA binding levels relative to parallel incubations without sulfite . Corresponding increases in mutagenicity were seen as well . As sulfite can affect the glutathione/glutathione-S-transferase systems, the primary cellular defense against BPDE, the effect of sulfite on these pathways in Salmonella was determined . When strain TA98 was treated with N-acetoxy-2-acetamidofluorene, a direct-acting mutagen not scavenged by glutathione, prior addition of 10 mM sulfite to the bacteria had no effect on resultant viability or mutagenicity . Assessment of the bacterial glutathione levels revealed that 10 mM sulfite treatment results in an 82% decrease in the concentration of the cosubstrate . We were, however, unable to detect diolepoxide-glutathione conjugates in any of our incubations . Moreover, the presence of sulfite leads to significant trapping of the diolepoxide in the form of sulfonate derivatives . Based on these data, we conclude that the depletion of glutathione does indeed play a role in the enhancement of diolepoxide mutagenicity in S . typhimurium.(ABSTRACT TRUNCATED AT 400 WORDS)

Res Microbiol, 1990 Sep-Oct, 141(7-8), 887 - 91
Immunization of mice with an attenuated Salmonella typhimurium strain expressing a membrane protein of Francisella tularensis . A model for identification of bacterial determinants relevant to the host defence against tularemia; Sjostedt A et al.; A 17-kilodalton (kDA) protein of the facultative intracellular bacterium Francisella tularensis is one of several membrane proteins that induce an in vitro response in T cells from F . tularensis-primed humans . A DNA fragment containing two genes, one of which encodes the 17-kDa protein, was cloned into an attenuated Salmonella typhimurium strain . Mice orally immunized with the recombinant S . typhimurium strain showed lower viable counts in livers and spleens after challenge with F . tularensis LVS (live vaccine strain) than did animals immunized with the non-recombinant strain . Cyclosporin A neutralized the protective effect of the recombinant S . typhimurium strain.

Res Microbiol, 1990 Sep-Oct, 141(7-8), 859 - 71
Protein antigens of Mycobacterium leprae; Clark-Curtiss JE et al.; Protein antigens of Mycobacterium leprae have been identified by screening the lambda gt11, pYA626 and pHC79::M . leprae genomic libraries with pooled sera from leprosy patients and with antiserum to M . leprae cell wall protein (CWP) aggregate . Immunological screening of the lambda gt11 library with pooled sera from 21 lepromatous (LL) leprosy patients resulted in the identification of 19 antigens that are apparently different from previously identified M . leprae antigens . Five additional antigens were identified by screening the lambda gt11 library with pooled sera from 30 borderline tuberculoid or tuberculoid patients . Four other antigens were identified by screening the lambda gt11 library with anti-CWP . Two groups of recombinant cosmids were identified by screening the pHC79 library with LL patients' sera: one group specified proteins that reacted with monoclonal antibodies (mAb) against the 65-kDa protein and against the 18-kDa protein; the other group specified a 15-kDa protein that did not react with any of the mAb that were tested . One pYA626 clone also specified a 15-kDa protein that reacted with LL patients' sera, but did not react with any mAb . Genes specifying several of these antigens have been subcloned into the Asd+ plasmid vector pYA292 and have been introduced into a delta cya delta crp delta asd Salmonella typhimurium strain to evaluate the ability of individual M . leprae proteins to elicit immune responses against M . leprae infection.

Res Microbiol, 1990 Sep-Oct, 141(7-8), 855 - 8
Expression of the envelope antigen of dengue virus in vaccine strains of Salmonella; Cohen S et al.; The envelope gene of dengue 4 virus (DEN) was cloned in a plasmid under the control of Escherichia coli expression signals . A clone that expressed 93% of the gene was found to be detrimental to the bacterial host . Another clone which carried only 76% of the E gene was found to be quite stable in vitro as well as in vivo . The killed recombinant bacteria induced antibodies in mice which recognized native DEN virus . Attenuated Salmonella typhimurium (SAL) strains carrying the DEN-E plasmid were tested for their efficacy as orally administered live vaccines . Protective immunization was assessed in a mouse model by immunizing three-week old BALB/c mice followed by challenge with DEN virus . It was found that these young mice were highly susceptible to the carrier SAL strains (M206 and aroA SL3261) . Moreover, the SAL-infected mice were more susceptible to DEN virus challenge than control mice, suggesting that the SAL infection caused immunosuppression in these young mice.

Res Microbiol, 1990 Sep-Oct, 141(7-8), 757 - 64
Immunity induced by live attenuated Salmonella vaccines; Hormaeche CE et al.; Studies on the degree and specificity of protection conferred by immunization with aroA salmonella live vaccines in BALB/c mice are described . Animals were immunized i.v . and challenged orally 3 months later to ensure that the vaccine had been cleared from the tissues . Vaccination with Salmonella typhimurium aroA SL3261 conferred very good protection against virulent S . typhimurium C5 (over 10,000 x LD50) . The specificity of cross protection was studied using S . typhimurium, Salmonella enteritidis and Salmonella dublin for vaccination and challenge, including challenge with variants of S . typhimurium and S . enteritidis of similar virulence which differed in the main LPS (lipopolysaccharide) antigen (0-4 or 0-9) . S . typhimurium SL3261 gave very good protection against S . typhimurium C5 (0-4), but no protection against S . enteritidis Se795 (0-9) . However, challenge with strains differing in the main 0 antigens showed that, although protection was generally better to strains expressing the same LPS type as the vaccine, specificity of protection was determined more by the background (S . typhimurium or S . enteritidis) of the parent strain used for the challenge than by 0 factors 4 or 9, suggesting that other factors could be involved . The nature of the antigen(s) responsible for protection in this model is unclear, but it would not appear to be the main 0-specific antigen . An S . enteritidis Se795 aroA vaccine was far less effective than S . typhimurium SL3261; it conferred good protection against the homologous wild type at 2 weeks post-vaccination, but far less at three months (approx 10-200 x LD50) . This was unexpected, as the persistence of the S . enteritidis vaccine in the liver and spleen was similar to that of S . typhimurium SL3261, and the S . enteritidis and S . typhimurium challenge strains were of similar virulence . An S . dublin aroA vaccine conferred similar protection against wild type S . dublin (approx 300 x LD50).

Genetika, 1990 Sep, 26(9), 1686 - 9
{Study of the DNA-damaging activity of the mutagenic derivative of tetrahydrodiazapyrene, DDDTDP}; Abilev SK et al.; 2,7-diamino-4,9-dioxo-5,10-dioxy-4,5,9,10-tetrahydro-4.9--diaza prein (DDDTDP)--the frameshift mutagen--induced frameshift mutations in indicator strain Salmonella typhimurium . The mutagen displays strong DNA damaging activity in murine L cell line . The DNA was analyzed for single strand breaks by alkaline elution assay . Analysis of reparation of DNA breaks suggests that DDDTDP acts as bifunctional agent.

Lancet, 1990 Sep 1, 336(8714), 545 - 9
Life-threatening bacteraemia in HIV-1 seropositive adults admitted to hospital in Nairobi, Kenya; Gilks CF et al.; During 6 months, 506 consecutive adult emergency admissions to hospital in Nairobi were enrolled in a study of bacteraemia and HIV infection . 19% were HIV-1 antibody positive . Significantly more HIV-seropositive than seronegative patients had bacteraemia (26% vs 6%) . The predominant organisms isolated from the seropositive patients were Salmonella typhimurium and Streptococcus pneumoniae . Mortality was higher in the seropositive than in the seronegative bacteraemic patients . The findings suggest that non-opportunistic bacteria are important causes of morbidity and mortality in HIV-infected individuals in Africa.

Res Microbiol, 1990 Sep-Oct, 141(7-8), 963 - 9
Immunogenicity of foreign peptide epitopes expressed in bacterial envelope proteins; O'Callaghan D et al.; We have used two bacterial proteins from Escherichia coli to express heterologous peptides . Both proteins are situated in the E . coli cell envelope but have different properties: LamB is an integral outer membrane protein, and MalE a soluble periplasmic protein . The peptides were expressed as genetic inserts within "permissive sites" of these recipient proteins, i.e . sites which allow the insertion of foreign peptides without affecting the biological properties of the host protein . In this paper, we summarize preliminary rules governing the immunogenicity of resulting LamB and MalE hybrid proteins when expressed in E . coli . We focus on two model epitopes: either peptide 132-145 from the preS(2) region of hepatitis B virus or peptide 93-103 from poliovirus VP1 capsid protein . We also present first results obtained when the same hybrid proteins were expressed in attenuated Salmonella typhimurium . Plasmids encoding the hybrid proteins were transferred to aroA S.typhimurium by electroporation . In vitro, the hybrid proteins could be expressed at high levels by S . typhimurium . Mice were immunized by parenteral and oral routes . The effect of the carrier protein and the level of its expression on the in vivo behaviour of the immunizing bacteria and on the immune response induced will be discussed.

Biochim Biophys Acta, 1990 Aug 27, 1050(1-3), 274 - 8
The role of EF-Tu and other translation components in determining translocation step size; Tuohy TM et al.; The two EF-Tu encoding genes, tufA and tufB, of Salmonella typhimurium have been sequenced . Nearly all the differences from their Escherichia coli counterparts are third position changes which do not alter the encoded amino acids . Unexpectedly, most of the changes in one Salmonella tuf gene are paralleled by changes in the other tuf gene perhaps due to gene repair despite the distance separating the genes . Three mutants which cause mis-framing, have their substitutions at codon 375 . Explanations for mutants which cause mis-framing are considered and the mechanism of normal reading frame maintenance discussed.

Ned Tijdschr Geneeskd, 1990 Aug 18, 134(33), 1611 - 3
{Small intestinal perforation as complication of loperamide treatment of Salmonella typhimurium infection}; Loffeld RJ et al.; A patient is described with an acute gastroenteritis, after ingestion of French fries and a raw egg and the simultaneous use of loperamide, due to an infection with Salmonella typhimurium phage type 10 . As a complication multiple perforations of the ileum developed which needed surgical resection . This is the first report of this complication in the literature . The simultaneous use of loperamide is suspected to be the promoting factor in the development of this complication.

Nature, 1990 Aug 16, 346(6285), 677 - 80
Abrupt changes in flagellar rotation observed by laser dark-field microscopy; Kudo S et al.; Bacteria such as Escherichia coli and Salmonella typhimurium swim by rotating their flagella, each of which consists of an external helical filament and a rotary motor embedded in the cell surface . The function of the flagellar motor has been examined mainly by tethering the flagellar filament to a glass slide and observing the resultant rotation of the cell body . But under these conditions the motor operates at a very low speed (about 10 r.p.s.) owing to the unnaturally high load conditions inherent in this technique . Lowe et al . analysed the frequency of light scattered from swimming cells to estimate the average rotation speed of flagellar bundles of E . coli as about 270 r.p.s . To analyse motor function in more detail, however, measurement of high-speed rotation of a single flagellum (at low load) with a temporal resolution better than 1 ms is needed . We have now developed a new method--laser dark-field microscopy--which fulfils these requirements . We find that although the average rotation speed of S . typhimurium flagella is rather stable, there are occasional abrupt slowdowns, pauses and reversals (accomplished within 1 ms) . These changes were frequently observed in mutants defective in one of the motor components (called the switch complex), suggesting that this component is important not only in switching rotational direction but also in torque generation or regulation.

J Immunol, 1990 Aug 15, 145(4), 1265 - 9
Role of CD4+ T cells and T-independent mechanisms in acquired resistance to Salmonella typhimurium infection; Nauciel C; Two aspects of acquired resistance to Salmonella typhimurium infection in BALB/c mice, i.e., the ability to clear the primary inoculum from the spleen and resistance to a secondary challenge, were studied with the use of mAb against T cell subsets . The ability to clear a temperature-sensitive mutant of S . typhimurium from the spleen (assessed at day 21) was abrogated by in vivo treatment with anti-CD4 mAb . Accelerated bacterial clearance could be adoptively transferred into naive mice . In vitro depletion experiments also showed the role of CD4+ T cells in this phenomenon . Depletion of CD8+ T cells had only a marginal effect . Resistance to reinfection in the late phase of the primary infection (day 50) was markedly depressed by in vivo treatment with anti-CD4 mAb, whereas this was not the case during the early phase (day 14) . Furthermore, during the early phase of infection athymic nude mice showed increased nonspecific resistance to reinfection . Taken together these results suggest that T-independent mechanisms play a major role in acquired resistance during the early phase of infection.

Echocardiography, 1990 Sep, 7(5), 657 - 60
Does pulsed-Doppler ultrasound have mutagenic effects? Application of the Ames mutagenicity assay to test pulsed-Doppler equipment; Meyenburg M et al.; Measurement of fetal blood flow has been accepted using pulsed-Doppler ultrasound . Until recently, there has been a lack of investigations concerning the potential risks of this method . The possible mutagenic effect of a pulsed-Doppler system was examined in vitro by applying the Ames test . Tester strains of Salmonella typhimurium indicating point mutations were irradiated (TA 98, TA 100, TA 102, TA 1535, TA 1537, TA 1538) . A commercially available duplex system was applied in the experiments emitting an ultrasound beam with a spatial-peak temporal-average of 5.2 mW/cm2 and a spatial-peak temporal-peak of 117 mW/cm2 at a frequency of 2 MHz . The tester strains were sonicated up to 60 minutes, the bacterial suspension being in direct contact with the transducer surface . The ultrasound-exposed bacterial suspensions were compared with nonexposed samples . Reference mutagens were used for checking the sensitivity of the system . The results do not indicate any mutagenic effects.

Environ Health Perspect, 1990 Aug, 88, 43 - 8
Sulfotransferase-mediated chlorination of 1-hydroxymethylpyrene to a mutagen capable of penetrating indicator cells; Glatt H et al.; Methylated polycyclic aromatic hydrocarbons are common in the human environment . Many of them are stronger carcinogens than their purely aromatic congeners . They may be metabolized to benzylic alcohols . We report here on biochemical and toxicological characteristics of 1-hydroxymethylpyrene (HMP), a typical representative of this class of compounds . Rat liver cytosol, fortified with 3'-phosphoadenosine-5'-phosphosulfate, converted HMP into its sulfate ester (HMPS), HMPS bound covalently to isolated DNA . In physiological buffer at 37 degrees C, HMPS had a half-life of 2 min, the major decomposition product being HMP . Thus, cyclic activation is possible . When Cl- anions were present at physiological concentrations, an additional reaction product of HMPS, 1-chloromethylpyrene (ClMP), could be identified on the basis of its chromatographic properties and its mass spectrum, using the authentic standard for comparison . ClMP was shorter-lived in buffer than HMPS . ClMP reacted with DNA, the adduct pattern in the 32P-postlabeling analysis being similar, or identical, to that of HMPS . ClMP proved to be a very potent mutagen in Salmonella typhimurium, whereas HMPS, and HMP in the presence of a sulfate-conjugating system, showed strong mutagenicity only when Cl- or Br- ions were present in the exposure buffer . It is concluded that HMPS is capable of reacting with DNA, but is hampered in its distribution by membrane barriers.(ABSTRACT TRUNCATED AT 250 WORDS)

Environ Health Perspect, 1990 Aug, 88, 37 - 41
Stereoselective metabolism of dibenz(a,h)anthracene to trans-dihydrodiols and their activation to bacterial mutagens; Platt KL et al.; Dibenz(a,h)anthracene (DBA), a carcinogenic, polycyclic aromatic hydrocarbon ubiquitous in the environment, is metabolized by the hepatic microsomal fraction of immature Sprague-Dawley rats pretreated with Aroclor 1254 to 27 ethyl acetate-extractable metabolites . More than half of these metabolites (51%) consisted of trans-1,2-; -3,4-; and -5,6-dihydrodiols including their identified secondary metabolites . The three trans-dihydrodiols (4.9, 15.8, and 0.6% of total metabolic conversion) were highly enriched in their R,R enantiomers (85, 71, and 98%) as determined by high performance liquid chromatography on suitable chiral stationary phases . This is explained on the basis of the stereoselective epoxidation of DBA by cytochrome P-450c (induced by Aroclor 1254) followed by regioselective hydration catalyzed by microsomal epoxide hydrolase . Determination of the bacterial mutagenicity by measuring the reversion rate of histidine-dependent Salmonella typhimurium TA100 to histidine prototrophy revealed marked differences in the mutagenicity of the enantiomers of the trans-dihydrodiols of DBA when activated by the same metabolizing system as used in the metabolism studies . In the case of trans-1,2- and -5,6-dihydrodiol, the S,S enantiomers were converted to more mutagenic metabolites than their corresponding optical antipodes, whereas in the case of trans-3,4-dihydrodiol it was the R,R enantiomer that produced the stronger mutagens . Therefore, both regio- and stereoselectivity of the metabolizing enzymes attribute to the dominant role of trans-3,4-dihydrodiol in the mutagenicity of DBA.

Environ Health Perspect, 1990 Aug, 88, 27 - 31
A novel pathway to the ultimate mutagens of aromatic amino and nitro compounds; Wild D; Photolysis of arylazides in aqueous media was recently found to generate presumed nitrenium ions, species which are generally considered as the ultimate mutagens/carcinogens derived from arylamines and nitroarenes . The primary photolysis products of arylazides, the arylnitrenes, can possibly react as electrophiles themselves, or they can be protonated and thus form the electrophilic nitrenium ions . Numerous arylazides and aryldiazides can be photoactivated to short-lived mutagens detectable in Salmonella typhimurium TA98 . Structure-activity comparisons between arylazides and the matching arylamines and nitroarenes show correlations; e.g., phenyl azide and methyl-substituted phenyl azides are not mutagenic or only weakly mutagenic like aniline, nitrobenzene, and their methyl homologues, whereas 4-azidodiphenyl, 2-azidofluorene, 1-azidopyrene, azido-IQ, and azido-isoIQ are increasingly mutagenic in that order, like the matching amino and nitro compounds . It is hypothesized on the basis of these data that the nitrene/nitrenium ion is the reactive intermediate common to the three mutagenic pathways and that the reaction of the nitrene/nitrenium ion with DNA is rate limiting for the overall mutagenic process in Salmonella . The photochemical generation from arylazides of the reactive species, the nitrene/nitrenium ions, opens new perspectives for the understanding of the genotoxic activity of arylamines and nitroarenes in general and, specifically, of the food mutagens/carcinogens of the IQ type.

Environ Health Perspect, 1990 Aug, 88, 111 - 5
Identification of ultimate DNA damaging oxygen species; Epe B et al.; DNA damage induced by various reactive oxygen species can be characterized using a set of repair endonucleases with defined substrate specificities . DNA damage profiles thus obtained in a cell-free system can be compared with those observed in cellular DNA . Using this approach, we have demonstrated that an illumination of Salmonella typhimurium cells with visible light in the presence of methylene blue gives rise to a DNA damage profile very similar to that of singlet oxygen in a cell-free system . Therefore, the genotoxicity observed under these conditions most probably is attributable to the direct action of this species . The damage consists mainly of base modifications that are subject to repair by uvrABC-independent pathways . Revertant frequencies observed in parallel in the strains TA100 and TA2638 indicate a pronounced mutagenicity of the lesions induced . Exposure of Salmonella typhimurium to tert-butylhydroperoxide gives rise to another form of damage profile that is also different from that produced by hydroxyl radicals in a cell-free system . However, the latter dissimilarity does not exclude hydroxyl radicals as ultimate reactive species, as a very rapid repair of the induced base modifications is observed, which might have distorted the damage profile despite immediate work up.

Mol Gen Genet, 1990 Aug, 223(1), 156 - 8
High efficiency transformation of Salmonella typhimurium and Salmonella typhi by electroporation; O'Callaghan D et al.; Salmonella typhimurium and S . typhi were transformed with high efficiency by electroporation . Transformation efficiencies of up to 10(10) transformants per microgram of pBR322 were obtained . In contrast to chemical transformation methods, neither the smooth lipopolysaccharide of S . typhimurium nor the Vi capsular polysaccharide of S . typhi greatly affected transformation efficiency . The introduction of a ga1E mutation slightly improved transformation efficiency in S . typhimurium (less than tenfold) while the Vi antigen of S . typhi had no detectable effect . The transformation efficiency of S . typhimurium with DNA derived from Escherichia coli was increased greatly by the removal of the hsd restriction system (100-fold) . Under these conditions electroporation can be used for the routine and direct transformation of Salmonella strains with partially purified (alkaline lysis) plasmid DNA from E . coli.

Can J Microbiol, 1990 Aug, 36(8), 582 - 4
Bactericidal activity of magainin 2: use of lipopolysaccharide mutants; Macias EA et al.; Salmonella typhimurium and a series of rough lipopolysaccharide mutants derived from it were used as target bacteria to examine the antimicrobial capacity of magainin 2 . Magainin 2 demonstrated a dose-related bactericidal activity against the smooth parent strain and the series of lipopolysaccharide mutants . The lipopolysaccharide mutant series showed an ordered increase in sensitivity to the magainin 2 as the depth of the rough lesion in the lipopolysaccharide increased.

Pediatr Infect Dis J, 1990 Aug, 9(8), 551 - 5
The use of prophylactic furazolidone to control a nosocomial epidemic of multiply resistant Salmonella typhimurium in pediatric wards; Kassis I et al.; The nosocomial spread of enteric pathogens is often difficult to control in overcrowded pediatric wards . During 1983 and 1984, despite cohorting of patients and enforced hand washing, more than 200 cases of nosocomial multiply resistant Salmonella typhimurium phage type R-9 were observed on two adjacent pediatric wards . Most cases occurred during the summer months . After 19 new cases were detected early in the summer of 1985, oral administration of furazolidone throughout their entire hospital stay (2.5 mg/kg twice daily) was recommended for all subsequently hospitalized infants . Among the 114 (65%) infants who were appropriately treated, only one additional case (1%) was detected . In contrast 11 (19%) cases occurred among the 59 infants who were inappropriately treated: 5 of 35 (14%) of those who were not treated and 6 of 24 (25%) in whom treatment with furazolidone was delayed greater than 24 hours (P less than 0.001 between the appropriately and inappropriately treated groups) . In pediatric wards where infection control measures cannot be optimally applied, prophylactic furazolidone administration may be helpful in preventing the spread of enteric pathogens.

Aust Vet J, 1990 Aug, 67(8), 294 - 8
Evaluation of protection against experimental salmonellosis in sheep immunised with 1 or 2 doses of live aromatic-dependent Salmonella typhimurium; Begg AP et al.; The minimum number of doses of a live aromatic dependent (aro-) Salmonella typhimurium vaccine strain (SL1479), given by the intramuscular, oral or subcutaneous route required to protect sheep from experimentally-induced clinical salmonellosis, was determined . A significant reduction in mortalities and diarrhoea occurred in those sheep immunised with one or 2 intramuscular doses or 2 subcutaneous doses . On the other hand, sheep immunised with one subcutaneous dose were not protected . Immunisation with one or 2 oral doses also resulted in a significant reduction in mortality, although reduction in the prevalence of severe diarrhoea was less consistent . Sheep immunised with a single intramuscular dose of aro- S . typhimurium developed high levels of serum antibodies and significant delayed-type cutaneous hypersensitivity response to homologous Salmonella lipopolysaccharide and flagellin, whereas those with a single oral dose did not . It was concluded that immunisation of sheep with a single oral or intramuscular dose of live aro- S . typhimurium reduced mortalities and the prevalence of diarrhoea in sheep due to infection with virulent S . typhimurium.

Rontgenblatter, 1990 Aug, 43(8), 359 - 61
{Salmonella osteomyelitis involving multiple bones in chronic myeloid leukemia}; Schnabel T et al.; Salmonella osteomyelitis associated with sickle cell anemia has been reported in numerous cases and also in few cases of patients under immunosuppression or suffering from malignant disease . Involvement of multiple bones by an infection with salmonella typhimurium is rare . Intracortical fissures which are detectable on x-ray films after some weeks are looked upon as typical for a salmonella osteomyelitis . Bone scan, computed tomography or MR tomography are supplementary examinations in the diagnosis of salmonella osteomyelitis.

Genetics, 1990 Aug, 125(4), 709 - 17
Analysis of sequence elements important for expression and regulation of the adenylate cyclase gene (cya) of Salmonella typhimurium; Thorner LK et al.; We determined the nucleotide sequence of the regulatory region of the cya gene of Salmonella typhimurium . A set of nested BAL-31 deletions originating upstream of the promoter/regulatory region and extending into the cya structural gene was constructed in M13mp::cya phages and was tested for complementation of a chromosomal cya deletion mutation . BAL-31 deletion mutants unable to complement cya localized the major cya promoter . The synthetic tac promoter was inserted upstream of the BAL-31 deletions so that expression of cya was dependent on transcription from tac . Those tac derivative phages unable to complement cya localized the translation initiation region . The cya DNA sequence revealed at least three potential promoters capable of transcribing cya, with a CRP binding site straddling the-10 hexamer of the promoter proximal to the structural gene . The leader RNA sequence initiated at the latter promoter is approximately 140 bases long and includes a region that may form a stable secondary structure (delta G = -23.8 kcal) . There exist two possible in-frame translation start points, one of which is TTG and the other of which is ATG . The sequence of the S . typhimurium regulatory region was compared with that reported for Escherichia coli.

Mutat Res, 1990 Aug, 244(4), 321 - 9
A comparative study of mutagenic and SOS-inducing activity of biphenyls, phenanthrenequinones and fluorenones; Vasilieva S et al.; A total of 23 chemicals--biphenyls, phenanthrenequinones and fluorenones--were tested for mutagenicity towards Salmonella typhimurium strains TA1538, TA1535 and TA98 . SOS-inducing activity of the same chemicals was studied in terms of the SOS-inducing potency in Escherichia coli PQ37, using an automated instrument controlled by a dedicated computer program for the SOS Chromotest . Of the 23 chemicals studied 14 induced His+ revertants in S . typhimurium TA1538 hisD305 (-1 frameshift); none induced His+ reversions in TA1535 (base-pair substitution) . The mutagenicity of the chemicals in S . typhimurium TA98 (pKM 101) was lower than in TA1538 . There was a close correlation between mutagenicity and SOS-inducing activity of fluorenones and phenanthrenequinones . None of the biphenyls tested induced SOS response and this property does not depend upon the mutagenic activity of the chemicals . SOS Chromotest is particularly valid in detecting chemicals which give rise to base-pair substitutions through SOS induction . If positive results are obtained, the Salmonella assay may be omitted . However, this test cannot replace the Ames test especially for the primary screening of mutagenicity of chemicals with unknown structure.

Mutat Res, 1990 Aug, 244(4), 303 - 8
Mutagenicity of commercial hair dyes and detection of 2,7-diaminophenazine; Watanabe T et al.; Four commercial oxidative-type hair dye formulations, A, B, C, and D, were treated with hydrogen peroxide (H2O2) to simulate normal conditions of use, and the oxidized hair dyes were tested for their mutagenicity in Salmonella typhimurium TA98 in the presence of a mammalian metabolic activation system (S9 mix) . Most of them did not show obvious mutagenicity in the range of 1-25 microliters/plate and all exhibited bactericidal activity at 10 microliters/plate . In order to evaluate the mutagenicity of hair dyes both before and after H2O2 oxidation, rayon linked to a copper-phthalocyanine derivative (blue rayon) was used as an adsorbent for the elimination of interfering bactericidal compounds . Adsorbed compounds on blue rayon were eluted with ammoniacal methanol and eluents were subjected to the Ames test . The mutagenicity of the blue-rayon extracts in TA98 with S9 mix was increased by H2O2 oxidation . The blue-rayon extracts obtained from oxidized A and B were potent mutagens and reverted 334 and 999 colonies/10 microliters of original substance, respectively . In addition, 88 and 249 ng of 2,7-diaminophenazine, which was extremely mutagenic in TA98 with S9 mix, were detected in the extracts of 40 ml of the hair dye formulations A and B, respectively . The mutagenicity in oxidized hair dye formulations was successfully detected by use of blue-rayon extraction . 2,7-Diaminophenazine was only formed in the hair dye formulations containing m-phenylenediamine by H2O2 oxidation . Therefore, attention needs to be paid to the use of m-phenylenediamine as a hair dye component, not only for its own toxicity but also for that of its oxidation products.

Mutat Res, 1990 Aug, 231(2), 205 - 18
Epoxides: comparison of the induction of SOS repair in Escherichia coli PQ37 and the bacterial mutagenicity in the Ames test; von der Hude W et al.; The genotoxicity of 51 epoxides is studied with the SOS-Chromotest using Escherichia coli PQ37 as tester strain . The results obtained with this test system are compared with results of the Ames test . Out of 51 epoxides, 39 are shown to be mutagenic in Salmonella typhimurium whereas only 27 mutagenic epoxides induced the SOS response in Escherichia coli PQ37.

J Surg Res, 1990 Aug, 49(2), 126 - 31
Induction of endogenous tissue antioxidant enzyme activity attenuates myocardial reperfusion injury; Bensard DD et al.; Efforts to reduce reperfusion injury have focused on exogenous therapies; however, endogenous attenuation of reperfusion injury can be induced by a single sublethal dose of endotoxin (ETX) prior to ischemia . The purposes of this study were to investigate (i) the early neutrophil-endothelial (PMN-EC) adherence, (ii) the associated myocardial oxidant stress, (iii) the relationship of oxidant stress to antioxidant enzyme activity, and (iv) the correlation of increased antioxidant enzyme activity to myocardial recovery following ischemia/reperfusion (I-R) injury at 36 hr . Rats were administered a sublethal dose (2% of LD50) of endotoxin (500 micrograms/kg, ip, Salmonella typhimurium) . At 6 hr, myocardial neutrophil accumulation (histology), hydrogen peroxide (H2O2) levels, and myocardial tissue glutathione (glutathione and oxidized glutathione) levels were determined . At 24 hr myocardial tissue glutathione levels and catalase (CAT) activity were assayed . At 36 hr, myocardial tissue superoxide dismutase, glutathione peroxidase, glutathione reductase, catalase, and glucose-6-phosphate dehydrogenase (G-6-PD) were assayed . At 36 hr, hearts were subjected to a standard (20 min, global, 37 degrees C) ischemic insult followed by reperfusion . At 40 min of reperfusion, ventricular function was assessed (ventricular balloon; ventricular developed pressure +dP/dt, and -dP/dt).(ABSTRACT TRUNCATED AT 250 WORDS)

Mutat Res, 1990 Aug, 241(4), 349 - 54
Evaluation of the mutagenicity of 'pan masala', a chewing substitute widely used in India; Bagwe AN et al.; Mutagenicity of polar and non-polar extracts of a popular brand of 'pan masala' was examined using the Salmonella/mammalian microsome test (Ames assay) and 2 tester strains of Salmonella typhimurium, TA98 and TA100 . These extracts were also subjected to pretreatment with sodium nitrite at acidic pH, to simulate conditions for endogenous nitrosation . The aqueous, aqueous:ethanolic and chloroform extracts as well as their nitrosated mixtures were non-mutagenic in the Ames assay, in the presence and absence of metabolic activation . Only the ethanolic extract elicited a weak mutagenic response in strain TA98 without metabolic activation demonstrating the presence of direct-acting frameshift mutagens in 'pan masala'.

J Bacteriol, 1990 Aug, 172(8), 4392 - 8
Molecular cloning and physical and functional characterization of the Salmonella typhimurium and Salmonella typhi galactose utilization operons; Houng HS et al.; The chromosomally encoded galactose utilization (gal) operons of Salmonella typhimurium and S . typhi were each cloned on similar 5.5-kilobase HindIII fragments into pBR322 and were identified by complementation of Gal- Escherichia coli strains . Restriction endonuclease analyses indicated that these Salmonellae operons share considerable homology, but some heterogeneities in restriction sites were observed . Subcloning and exonuclease mapping experiments showed that both operons have the same genetic organization as that established for the E . coli gal operon (i.e., 5' end, promoter, epimerase, transferase, kinase, and 3' end) . Two gal operator regions (oE and oI) of S . typhimurium, identified by repressor titration in an E . coli superrepressor {galR(Sup)} mutant, were sequenced and found to flank the promoter region . This promoter region is identical to the -10 and -35 regions of the E . coli gal operon . Minicell studies demonstrated that the three gal structural genes of S . typhimurium encode separate polypeptides of 39 kilodaltons (kDa) (epimerase, 337 amino acids {aa's}), 41 kDa (transferase, 348 aa's), and 43 kDa (kinase, 380 aa's) . Despite functional and organizational similarities, DNA sequence analysis revealed that the S . typhimurium gal genes show less than 70% homology to the E . coli gal operon . Because of codon degeneracy, the deduced amino acid sequences of these polypeptides are highly conserved (greater than 90% homology) as compared with those of the E . coli gal enzymes . These studies have defined basic genetic parameters of the gal genes of two medically important Salmonella species, and our findings support the hypothesized divergent evolution of E . coli and Salmonella spp . from a common ancestral parent bacterium.

J Bacteriol, 1990 Aug, 172(8), 4359 - 69
Genetic and behavioral analysis of flagellar switch mutants of Salmonella typhimurium; Magariyama Y et al.; At the interface between the sensory transduction system and the flagellar motor system of Salmonella typhimurium, the switch complex plays an important role in both sensory transduction and energy transduction . To examine the function of the switch complex, we isolated from 10 cheY mutants 500 pseudorevertants with a suppressor mutation in one of the three genes (fliG, fliM, and fliN) encoding the switch complex . Detailed mapping revealed that these suppressor mutations were localized to several segments of each switch gene, suggesting localization of functional sites on the switch complex . These switch mutations were introduced into the wild-type background and into a chemotaxis deletion background . Behavior of the pseudorevertants and their derivatives (1,500 strains in all) was observed by light microscopy . In the chemotaxis deletion background, about 70% of the switch mutants showed smooth swimming and the rest showed more or less tumbly swimming . There was some correlation between the mutational sites and the swimming patterns in the chemotaxis deletion background, suggesting that there is segregation of functional sites on the switch complex . The interaction of the switch complex with the chemotaxis protein, CheY, and the stochastic nature of switching in the absence of CheY are discussed.

J Bacteriol, 1990 Aug, 172(8), 4187 - 96
Regulation of NAD metabolism in Salmonella typhimurium: molecular sequence analysis of the bifunctional nadR regulator and the nadA-pnuC operon; Foster JW et al.; In Salmonella typhimurium, de novo synthesis of NAD is regulated through the transcriptional control of the nadA and nadB loci . Likewise, the pyridine nucleotide salvage pathway is controlled at pncB . The transcriptional expression of these three loci is coordinately regulated by the product of nadR . However, there is genetic evidence suggesting that NadR is bifunctional, serving in both regulatory and transport capacities . One class of mutations in the nadR locus imparts a transport-defective PnuA- phenotype . These mutants retain regulation properties but are unable to transport nicotinamide mononucleotide (NMN) intact across the cell membrane . Other nadR mutants lose both regulatory and transport capabilities, while a third class loses only regulatory ability . The unusual NMN transport activity requires both the PnuC and NadR proteins, with the pnuC locus residing in an operon with nadA . To prove that nadR encoded a single protein and to gain insight into a regulatory target locus, the nadR and nadA pnuC loci were cloned and sequenced . A DNA fragment which complemented both regulatory and transport mutations was found to contain a single open reading frame capable of encoding a 409-amino-acid protein (47,022 daltons), indicating that NadR is indeed bifunctional . Confirmation of the operon arrangement for nadA and pnuC was obtained through the sequence analysis of a 2.4-kilobase DNA fragment which complemented both NadA and PnuC mutant phenotypes . The nadA product, confirmed in maxicells, was a 365-amino-acid protein (40,759 daltons), while pnuC encoded a 322-amino-acid protein (36,930 daltons) . The extremely hydrophobic (71%) nature of the PnuC protein indicated that it was an integral membrane protein, consistent with its central role in the transport of NMN across the cytoplasmic membrane . The results presented here and in previous studies suggest a hypothetical model in which NadR interacts with PnuC at low internal NAD levels, permitting transport of NMN intact into the cell . As NAD levels increase within the cell, the affinity of NadR for the operator regions of nadA, nadB, and pncB increases, repressing the transcription of these target genes.

Virology, 1990 Aug, 177(2), 445 - 51
Capsomer proteins of bacteriophage PRD1, a bacterial virus with a membrane; Bamford JK et al.; Bacteriophage PRD1 infecting Escherichia coli and Salmonella typhimurium translocates its membrane from the host plasma membrane to the virus particle . One obligatory component in this process is the major capsid protein . In this investigation we describe characteristics of the homomultimeric major and minor capsid proteins including the sequences of the corresponding genes . The minor capsid protein was found to contain a short collagen-like region (Gly-X-Y)6 . This is the first time this motif has been reported for a prokaryotic protein.

Genetics, 1990 Aug, 125(4), 719 - 27
Mutations that affect transcription and cyclic AMP-CRP regulation of the adenylate cyclase gene (cya) of Salmonella typhimurium; Fandl JP et al.; We studied the expression of the cya promoter(s) in cya-lac fusion strains of Salmonella typhimurium and demonstrated cAMP receptor protein (CRP)-dependent repression by cAMP . Expression of cya was reduced about fourfold in cultures grown in acetate minimal medium as compared to cultures grown in glucose-6-phosphate minimal medium . Expression of cya was also reduced about fourfold by addition of 5 mM cAMP to cultures grown in glucose minimal medium . We constructed in vitro deletion and insertion mutations altering a major cya promoter (P2) and a putative CRP binding site overlapping P2 . These mutations were recombined into the chromosome by allele replacement with M13mp::cya recombinant phages and the regulation of the mutant promoters was analyzed . A 4-bp deletion of the CRP binding site and a 4-bp insertion in this site nearly eliminated repression by cAMP . A mutant with the P2 promoter and the CRP binding site both deleted exhibited an 80% reduction in cya expression; the 20% residual expression was insensitive to cAMP repression . This mutant retained a Cya+ phenotype . Taken together, the results establish that the cya gene is transcribed from multiple promoters one of which, P2, is negatively regulated by the cAMP-CRP complex . Correction for the contribution to transcription by the cAMP-CRP nonregulated cya promoters indicates that the P2 promoter is repressed at least eightfold by cAMP-CRP.

Immunology, 1990 Aug, 70(4), 540 - 6
Anti-viral immunity induced by recombinant nucleoprotein of influenza A virus . III . Delivery of recombinant nucleoprotein to the immune system using attenuated Salmonella typhimurium as a live carrier; Tite JP et al.; A plasmid encoding the influenza nucleoprotein gene from A/NT/60/68 virus was transduced into the attenuated Salmonella typhimurium aroA- strain SL3261 . The bacterial vector expressing the viral gene product was able to induce both humoral and cell-mediated immune responses to the nucleoprotein antigen . CD4+ virus-specific T cells capable of proliferation were readily induced and, in some circumstances, class II major histocompatibility complex (MHC)-restricted cytotoxicity was detected . However, virus-specific class I MHC-restricted cytotoxic T lymphocytes (CTL) were not detected after such immunization . Mice immunized orally with the nucleoprotein-expressing bacteria mounted a strong anti-viral antibody response and spleen cells from such mice proliferated specifically to virus challenge in vitro, producing interferon-gamma (IFN-gamma) and interleukin-2 (IL-2) . Orally immunized mice showed significant protection from challenge infection with influenza virus if the mice were also boosted intranasally before infection.

Proc Natl Acad Sci U S A, 1990 Aug, 87(15), 5898 - 902
FrzE of Myxococcus xanthus is homologous to both CheA and CheY of Salmonella typhimurium; McCleary WR et al.; Myxococcus xanthus exhibits multicellular development . The "frizzy" (frz) mutants are unable to complete the developmental pathway . Instead of forming fruiting bodies, these mutants form tangled filaments of cells . We have previously shown that four of the frz gene products are homologous to enteric chemotaxis proteins and have proposed that the frz genes constitute a signal-transduction pathway that controls the frequency at which cells reverse their gliding direction . We show here that frzE encodes a protein with a calculated molecular mass of 83 kDa . FrzE is homologous to both CheA and CheY of Salmonella typhimurium, which are members of a family of "two-component response regulators." It is thought that the modulator components autophosphorylate and transfer a phosphate group to their cognate effector components . FrzE contains an unusual (alanine plus proline)-rich region that might constitute a flexible hinge facilitating phosphate transfer between functional domains . We suggest that FrzE is a second messenger that relays information between the signaling protein FrzCD and the gliding motor.

Infect Immun, 1990 Aug, 58(8), 2651 - 8
Genetic and DNA sequence analysis of the Salmonella typhimurium virulence plasmid gene encoding the 28,000-molecular-weight protein; Gulig PA et al.; We have confirmed that the 28,000-molecular-weight (28K) protein encoded by the virA gene of the 90-kilobase Salmonella typhimurium virulence plasmid is a virulence factor . It was previously shown that a Tn5 insertion, vir-22::Tn5, located in the virulence plasmid greatly attenuated virulence for mice and inhibited the production of a 28K protein (P.A . Gulig and R . Curtiss III, Infect . Immun . 56:3262-3271, 1988) . Plasmid pYA426 fully complemented vir-22::Tn5 to virulence by increasing splenic infection after oral inoculation and encoded the 28K protein . To identify the virulence gene(s) of pYA426 mutated by vir-22::Tn5, we constructed nested deletions in pYA426 and examined deletion derivatives for their abilities to complement vir-22::Tn5 . Only derivatives still producing the 28K protein complemented vir-22::Tn5 . Furthermore, the smallest complementing derivative encoded only the 28K protein, as determined by DNA sequence analysis . Therefore, the 28K protein is sufficient for complementation of the attenuating mutation vir-22::Tn5 and must be the virulence factor inhibited by the insertion . We determined the nucleotide sequence of the 1.2-kilobase BamHI-EcoRI fragment encoding the 28K protein and identified the structural gene, virA . A 723-base-pair open reading frame which encodes a peptide with a molecular weight of 27,572 was found.

Appl Environ Microbiol, 1990 Aug, 56(8), 2410 - 6
Iron-binding compounds and related outer membrane proteins in Vibrio cholerae non-O1 strains from aquatic environments; Amaro C et al.; A total of 156 strains of Vibrio cholerae non-O1 from aquatic origins were examined for the presence of iron uptake mechanisms and compared with O1 strains and other Vibrio species . All non-O1 strains were able to grow in iron-limiting conditions, with MICs of ethylenediaminedi (O-hydroxyphenylacetic acid) ranging from 20 microM to 2 mM . The production of siderophores was demonstrated by growth in chrome azurol S agar and cross-feeding assays . All strains produced phenolate-type compounds, as assessed by the chemical tests and by bioassays with Salmonella typhimurium enb-7 . Some of the strains also promoted the growth of S . typhimurium enb-1 (which can use only enterobactin as a siderophore) as well as some strains of Vibrio anguillarum deficient in the anguibactin-mediated system . The chromatographic analyses and absorption spectra of siderophores extracted from culture supernatants suggest that vibriobactin may be produced by the strains examined . Interestingly, some strains also produced hydroxamate-type compounds, as determined by chemical tests, and were able to promote the growth of an aerobactin-deficient strain of Escherichia coli . These results were confirmed by the absorption spectra and chromatographic analyses of the culture extracts . The synthesis of iron-regulated outer membrane proteins in representative strains was also examined . The molecular sizes of the main induced proteins ranged from 70 to 78 kilodaltons . These results indicate that several iron uptake mechanisms which could be involved in environmental survival and pathogenicity are present in environmental V . cholerae non-O1 strains.

Environ Health Perspect, 1990 Aug, 88, 89 - 97
Photobiological studies with dioxetanes in isolated DNA, bacteria, and mammalian cells; Adam W et al.; 1,2-Dioxetanes, efficient chemical sources of triplet excited carbonyl compounds, were observed to be genotoxic in isolated DNA, bacteria, and cultured mammalian cells . In superhelical DNA of bacteriophage PM2, various alkyl- and hydroxyalkyl-substituted dioxetanes (1) induced predominantly endonuclease-sensitive base modifications and only few single strand breaks . With a specific endonuclease a small fraction of the base modifications was identified as pyrimidine dimers . The psoralen dioxetane (2a) or PsD bound photochemically to calf thymus DNA at the alpha-pyrone ring of psoralen (fluorescence measurements) . Photobinding was also observed when calf thymus DNA was incubated with psoralen and 3-hydroxymethyl-3,4,4-trimethyl-1,2-dioxetane . In Syrian hamster embryo fibroblasts and HL-60 cells, dioxetanes induced DNA single strand breaks . The alkyl- and hydroxyalkyl-substituted dioxetanes 1 and 2 were efficiently inactivated by cysteine, glutathione, ascorbic acid, tocopherol, NADH and FADH2 . While dioxetanes 1 and 2 were not mutagenic in Salmonella typhimurium strain TA100, benzofuran dioxetanes 3 exhibited substantial effects . Further data imply that presumably a mutagenic intermediate with a lifetime of a few minutes is produced from the benzofuran dioxetane.

J Appl Toxicol, 1990 Aug, 10(4), 239 - 43
A genotoxicological study of the new local anaesthetic carbamate derivatives carbisocaine, heptacaine and pentacaine; Siekel P; The potential mutagenic activity of three carbamate derivatives with local anaesthetic activity was investigated . Genotoxic activity was observed after application of Carbisocaine on Euglena gracilis, whereas no activity was detected by Carbisocaine, Heptacaine and Pentacaine on Salmonella typhimurium, Escherichia coli and Drosophila melanogaster.

Proc Natl Acad Sci U S A, 1990 Aug, 87(16), 6341 - 4
In vitro incorporation of selenium into tRNAs of Salmonella typhimurium; Veres Z et al.; Broken-cell preparations of Salmonella typhimurium rapidly incorporated 75Se from 75SeO3(2-) into tRNA by an ATP-dependent process . Selenium incorporation in the presence of 50 microM 75SeO3(2-) (0.8-1 pmol per A260 unit) was enhanced by the selenocysteine precursor, O-acetyl-L-serine (to 3.7 pmol per A260 unit) . This increase in incorporation was a function of O-acetyl-L-serine concentration . Neither O-acetyl-L-homoserine nor O-phospho-L-serine stimulated the incorporation of selenium into tRNA . The incorporation of 75Se from 75SeO3(2-) was decreased by adding L-selenocysteine but not by adding the D isomer . When homologous bulk tRNA was added to the broken-cell preparations, an increased rate of 75Se labeling was observed . The supernatant fraction of the broken-cell preparation contained all of the enzymes required for this process . Reversed-phase HPLC analysis of labeled bulk tRNA digested to nucleosides showed the presence of a labeled compound that coeluted with authentic 5-methylaminomethyl-2-selenouridine.

Mutat Res, 1990 Aug, 231(2), 251 - 64
DNA repair induced by various mutagens in rat hepatocyte primary cultures measured in the presence of hydroxyurea, guanazole or aphidicolin; Suter W et al.; Guanazole and aphidicolin were chosen as candidates in the search for a selective, non-genotoxic inhibitor of DNA replication which could be used instead of hydroxyurea to measure DNA repair synthesis in rat hepatocyte primary cultures by liquid scintillation counting . The genotoxicity of these 3 chemicals was studied using the Salmonella/liver homogenate assay and the autoradiographic UDS test in hepatocytes . Hydroxyurea was positive in both of these assays . Guanazole and aphidicolin did not induce DNA repair in hepatocytes . Aphidicolin was not mutagenic for Salmonella typhimurium, whereas guanazole increased the revertant numbers of strain TA102 slightly . The incorporation of {3H}thymidine was measured by liquid scintillation to determine DNA repair induced by 2-acetylaminofluorene (2-AAF), aflatoxin B1, benzo{a}pyrene, cyclophosphamide, H2O2, 6-hydroxydopamine, N-methyl-N'-nitro-N-nitrosoguanidine (MNNG), methylnitrosourea (MNU), 4-nitroquinoline-N-oxide and UV irradiation in the presence of either 10 mM hydroxyurea, 15 mM guanazole or 0.015 mM aphidicolin . Aphidicolin had an inhibitory effect on DNA repair . Except for the 3 chemicals mentioned below, the sensitivity of the DNA repair measurement was the same, no matter whether hydroxyurea or guanazole was used to inhibit replicative DNA synthesis . In the presence of hydroxyurea, DNA repair synthesis was found at lower concentrations in the case of aflatoxin B1, due to differences in the solvent control values, and in the case of H2O2, possibly due to a synergistic effect between hydroxyurea and H2O2 . Guanazole allowed the detection of DNA repair induced by MNNG at lower concentrations, probably because of an antagonistic effect between hydroxyurea and MNNG . Based on these results, it was concluded that guanazole, but not aphidicolin, could be used instead of hydroxyurea to measure DNA repair synthesis by liquid scintillation in rat hepatocyte primary cultures . Although guanazole does not completely fulfill the criteria for an ideal DNA replication inhibitor, it has the advantage of being less genotoxic than hydroxyurea, and also appears to have a smaller potential to falsify the results by interacting with the test compounds.

Mutat Res, 1990 Aug, 231(2), 243 - 9
Antimutagenic effects of mushrooms; Gruter A et al.; A heat-resistant factor in ethanol extracts of the fungus Craterellus cornucopioides completely inhibited the mutagenicity of aflatoxin B1, benzo{a}pyrene, the acridine half mustard ICR-191 and 2-nitrofluorene in a forward-mutation system using Salmonella typhimurium TM677 (screening for 8-azaguanine resistance) . There was no inhibitory effect on the mutagenic activity of 4-nitroquinoline-N-oxide, methyl methanesulfonate or N-methyl-N'-nitro-N-nitrosoguanidine . Experiments performed to elucidate the mechanism of the antimutagenic effect showed that neither an alteration of cell viability nor an interference with the excision-repair and the inducible SOS-repair system was involved . The conceivable mechanisms for the antimutagenicity of the ethanol extract include direct chemical interaction with the mutagen and/or inhibition of the activation process in the case of the promutagens . The antimutagenic activity of Craterellus cornucopioides is not unique among mushroom species . The ethanol extracts of 6 other mushrooms showed a similar antimutagenic activity.

J Bacteriol, 1990 Aug, 172(8), 4489 - 96
Novel Escherichia coli K-12 mutants impaired in S-adenosylmethionine synthesis; Satishchandran C et al.; S-Adenosylmethionine (AdoMet) plays a myriad of roles in cellular metabolism . One of the many roles of AdoMet in Escherichia coli and Salmonella typhimurium is as a corepressor of genes encoding enzymes of methionine biosynthesis . To investigate the metabolic effects of large reductions in intracellular AdoMet concentrations in growing cells, we constructed and examined mutants of E . coli which are conditionally defective in AdoMet synthesis . Temperature-sensitive mutants in metK, the structural gene for the S-adenosylmethionine synthetase (AdoMet synthetase) expressed in minimal medium, were constructed by in vitro mutagenesis of a plasmid-borne copy of metK . By homologous recombination, the chromosomal copy was replaced with the mutated metK gene . Both heat- and cold-sensitive mutants were examined . At the nonpermissive temperature, two such mutants had 200-fold-reduced intracellular AdoMet levels and required either methionine or vitamin B12 for growth . In the presence of methionine or vitamin B12, the mutants grew at normal rates even though the AdoMet levels remained 0.5% of wild type . A third mutant when placed at nonpermissive temperature had less than 0.2% of the normal AdoMet level and did not grow on minimal medium even in the presence of methionine or vitamin B12 . All of these mutants grew normally on yeast-extract-based medium in which an alternate form of S-adenosylmethionine synthetase was expressed.

Immunol Lett, 1990 Aug, 25(1-3), 109 - 14
Cellular mechanisms in immunity to blood stage infection; Kumar S et al.; We studied mechanisms of immunity to blood stage infection in the mouse malarias Plasmodium vinckei and Plasmodium yoelii 17X . Infection with P . vinckei was uniformly lethal, whereas P . yoelii 17X caused a self-limited, nonlethal infection . Transfer of immune CD4+ T cells conferred protection against P . yoelii in nude mice . Previous studies by others had suggested that immunity to P . yoelii may be related to MHC class I expression on reticulocytes and found that CD8+ T cells alone transferred protection in immunodeficient mice . However, in our experiments, immune CD8+ T cells failed to transfer protection . In the P . vinckei system, both B cell-deficient and immunologically intact mice developed immunity to P . vinckei after parasite infection and drug cure . In vivo depletion of CD4+ T cells abrogated immunity in these immune mice . Adoptive transfer of CD4+ T cells failed to protect nude or normal mice from P . vinckei infection, but the transfer of immune CD4+ T cells reconstituted immunity in CD4-depleted immune mice . Splenectomy of immune mice resulted in the complete loss of immunity . Despite the fact that immunity to P . vinckei could be achieved with live parasite infection and drug cure, immunization of mice with killed P . vinckei with various adjuvants failed to protect mice from live challenge . In contrast, immunization with killed P . vinckei antigens in combination with attenuated Salmonella typhimurium SL3235 induced a high degree of protective immunity . These results suggest that induction of immunity against virulent malarias requires both induction of CD4+ T cells and certain splenic alterations caused by parasite infection or S . typhimurium.(ABSTRACT TRUNCATED AT 250 WORDS)

Allergy, 1990 Aug, 45(6), 402 - 8
Bacteria and endotoxin enhance basophil histamine release and potentiation is abolished by carbohydrates; Clementsen P et al.; Histamine release caused by anti-IgE, specific antigens and calcium ionophore A23187 was examined in leukocyte suspensions from healthy individuals and patients allergic to house dust mite and birch pollen . Staphylococcus aureus and LPS from Salmonella typhimurium were found to cause a synergistic enhancement of the release . The potentiation of mediator release by the bacteria and the endotoxin depends on a binding to the basophilocyte, followed by a non-transient event, since the potentiating effect persists after preincubation of the cells with the LPS followed by washout and leaving the cells for 30 min at 37 degrees C before stimulation with anti-IgE . The potentiation was abolished or reduced by galactose (10(-7) and 10(-6) M) and N-acetylglucosamine (10(-6) and 10(-5) M), acting by a binding to the basophil cell membrane, demonstrated by the persistence of effect after preincubation and washout of unbound sugar.

Environ Res, 1990 Aug, 52(2), 225 - 30
Assessment of the mutagenic potential of ethanol auto engine exhaust gases by the Salmonella typhimurium microsomal mutagenesis assay, using a direct exposure method; Lotfi CF et al.; The mutagenic activity of the new Brazilian fuel, ethanol, was determined by employing the Salmonella typhimurium microsomal mutagenesis assay (TA97, TA98, TA100, TA102, and TA104) and a direct exposure method . This methodology was first used to determine the mutagenic activity of gasoline, revealing mutagenic activity of base-pair substitution without any need for metabolic activation, indicating the presence of direct-action mutagens . Experiments with ethanol suggest an indirect mutagenic activity of the oxidant type . The exposure system was considered suitable for future studies of gaseous mixtures.

Cancer Lett, 1990 Jul 16, 52(2), 123 - 31
Effect of glucose administration on hamster liver S9-mediated mutagenesis, metabolism and DNA-binding of benzo{a}pyrene and aflatoxin B1; Rubano DC et al.; Hamster liver S9 prepared from control animals and animals given 30% glucose in drinking water 48 h before killing was used in studies of benzo{a}pyrene (BaP) and aflatoxin (AFB1)-induced mutagenesis, metabolism of BaP and AFB1, and metabolite binding to calf thymus DNA . BAP-induced mutagenesis in Salmonella typhimurium TA100 was reduced 38.5% while AFB1-induced mutagenesis was increased 36% by S9 from glucose-treated hamsters . The reduction of {3H}BaP metabolite binding to calf thymus DNA in incubations with S9 from glucose-treated hamsters correlated with a decrease in unknown BP metabolite-deoxyribonucleoside adducts isolated by high performance liquid chromatography (HPLC) . Differences in the 7R and 7S-diol epoxide-1 and 2 deoxyguanosine adducts of BaP between control and glucose-treated S9 were not observed . HPLC analysis of AFB1-DNA adducts showed a 25% increase in {3H}AFB1-N7-guanine in incubations of glucose-treated S9 with {3H}AFB1 and calf thymus DNA . HPLC analysis of the organosoluble fraction of incubations with {3H}BaP and {3H}AFB1 indicated a significant effect by glucose-treated S9 on metabolism . The effect of glucose on metabolism was further reflected in the reduction of both BaP and AFB1 metabolite conjugation with glucuronide and glutathione as determined by separation on an alumina column . These results indicate that the oral administration of 30% glucose in drinking water alters hamster liver S9-mediated mutagenesis and binding of BaP and AFB1 metabolites to DNA through an effect on the metabolism of these two carcinogens.

Cancer Res, 1990 Jul 15, 50(14), 4300 - 7
Metabolic activation of the potent mutagen, 2-naphthohydroxamic acid, in Salmonella typhimurium TA98; Lee MS et al.; The objective of the present study was to explore the mechanisms responsible for the strong, direct-acting mutagenicity of 2-naphthohydroxamic acid (NHA) for Salmonella typhimurium TA98 . NHA was converted to its O-acetate (O-Ac-NHA) by acetyl-CoA, in the presence of competent or heat-treated cell-free bacterial preparations . O-Ac-NHA, which is more mutagenic than NHA, reacted nonenzymatically with tRNA in neutral solutions with retention of both the naphthyl and carbonyl groups in the products, but NHA did not react . Enzymatic sulfate conjugation was not demonstrated . TA98 cells converted NHA to 2-aminoaphthalene, presumably through a Lossen rearrangement following O-acetylation or conjugation by other metabolic pathways . TA98 cells reduced O-Ac-NHA to 2-naphthamide, and NADH and NADPH were shown to be cofactors for reduction in the presence of a cell-free bacterial preparation . Although horseradish peroxidase and H2O2 catalyzed the binding of these compounds to tRNA, no evidence of oxidation of NHA or O-Ac-NHA was obtained with H2O2 and cell-free preparations of TA98 or the cells themselves, as judged by the lack of formation of the peroxidative product, 2-naphthoic acid . Both NHA and O-Ac-NHA reacted with DNA of TA98 with retention of both naphthyl group and carbonyl of the naphthoyl moiety in the adduct(s) . These results suggest that NHA may be activated in TA98 by esterification, and the resulting metabolites may amidate or carbamoylate nucleic acids.

J Immunol, 1990 Jul 15, 145(2), 711 - 7
Bacteria-infected fibroblasts have enhanced susceptibility to the cytotoxic action of tumor necrosis factor; Klimpel GR et al.; The susceptibility of bacteria-infected fibroblasts to the cytotoxic action of tumor necrosis factor was investigated . L cells infected with Shigella flexneri, Salmonella typhimurium, or Listeria monocytogenes, had an enhanced susceptibility to the cytotoxic activity of TNF-alpha . This enhanced susceptibility was dependent upon the challenge dose of bacteria, the concentration of TNF, and upon the exposure time of bacteria-infected cells to TNF . L cells infected with S . flexneri were susceptible to the cytotoxic action of TNF at 2 to 6 h after bacterial infection . In contrast, L cells infected with S . typhimurium or L . monocytogenes did not show enhanced susceptibility to TNF until 14 h postbacterial infection and exposure to TNF . Enhanced susceptibility to TNF was dependent on bacterial invasion because fibroblasts pretreated with a noninvasive isogenic variant of S . flexneri, UV-treated invasive bacteria, bacterial cultural supernatant, or bacteria LPS were no more susceptible to TNF than untreated cells . Enhanced susceptibility to TNF by bacteria-infected cells was not unique to L cells . Mouse embryo fibroblasts and HeLa cells also showed similar reactivities after bacteria infection . Bacteria-infected cells were greatly suppressed in host cell protein synthesis that may play an important role in their enhanced susceptibility to TNF . These results suggest that an important role of TNF in host defense against bacterial infections is its cytotoxic activity against bacteria-infected cells.

J Mol Biol, 1990 Jul 5, 214(1), 97 - 104
Structural organization of flagellin; Vonderviszt F et al.; The terminal regions of flagellin from Salmonella typhimurium have been reported to be disordered in solution, whereas the central part of the molecule contains protease-resistant, compact structural units . Here, conformational properties of flagellin and its proteolytic fragments were investigated and compared to characterize the domain organization and secondary structure of flagellin . Deconvolution analysis of the calorimetric melting profiles of flagellin and its fragments suggests that flagellin is composed of three co-operative units or domains . The central part of the molecule, residues 179 to 418, consists of two domains (G1 and G2), whereas the third domain (G3) is discontinuous, constructed from segments 67 to 178 and 419 to 448 . Secondary structure prediction and analysis of far-ultraviolet circular dichroic spectra have revealed that G1 and G2 consist predominantly of beta-structure with a little alpha-helical content . G3 contains almost equal amounts of alpha and beta-structure, while in the terminal parts of flagellin the ordered secondary structure seems to be entirely alpha-helical.

Mol Gen Genet, 1990 Jul, 222(2-3), 438 - 40
Construction of plasmid-free derivatives of Salmonella typhimurium LT2 using temperature-sensitive mutants of pKZ1 for displacement of the resident plasmid, pSLT; Kelln RA et al.; Replication (or partitioning) temperature-sensitive mutants of pKZ1 were isolated and shown to exhibit incompatibility with the resident plasmid (pSLT) of Salmonella typhimurium LT2 . Following displacement of pSLT, the mutant plasmids were effectively eliminated from the cell population by passage at 42 degrees C, yielding plasmid-free isolates.

Mol Gen Genet, 1990 Jul, 222(2-3), 345 - 52
Translational coupling in the pyrF operon of Salmonella typhimurium; Theisen M et al.; The pyrF gene, encoding the sixth enzyme of pyrimidine biosynthesis in Salmonella typhirmurium, appears to be the first gene of an operon . The second gene, orfF, encodes a 11.5 kDa polypeptide of unknown function . To study the regulation of orfF expression directly, transcriptional and translational fusions of orfF to galK and lacZ, respectively, were constructed and the level of expression of the reporter genes was determined under different growth conditions . The results obtained show that the synthesis of OrfF and orotidine 5'-phosphate decarboxylase is coordinately controlled by pyrimidines, and that this control occurs at the level of transcription . The orfF translational start codon overlaps the pyrF translational stop codon, suggesting that the two genes are translationally coupled . This was investigated by studying how frameshift mutations, which cause premature termination of pyrF translation at different points, affect orfF expression . All mutations reduced orfF expression markedly without interfering with transcription of the gene . Thus, expression of pyrF and orfF are translationally coupled . Inspection of the nucleotide sequence of the pyrF/orfF junction region suggests that formation of secondary structures on the naked mRNA may explain the low level of orfF expression in the absence of translation of the pyrF terminal region.

Indian J Exp Biol, 1990 Jul, 28(7), 601 - 4
Detection of mutagenicity in cervico-vaginal secretions--a plausible risk factor for cervical cancer; Parashari A et al.; The cervico-vaginal secretions from 51 women with various grades of dysplastic lesions of uterine cervix were assessed for mutagenic potential by Ames test using histidine deficient mutant strain of Salmonella typhimurium TA-98: with S-9 mix . Twenty three per cent of samples from women with cervical dysplasia were found significantly positive (P less than 0.001) for mutagenic activity compared to 3% positive from control . The frequency of mutagenic secretions detected were almost uniform, irrespective of the severity of cervical lesions . None of cervico-vaginal secretions, positive for mutagenicity could revert the tester strain when tested in absence of S-9 mix (liver microsomal enzymes) . This indicates that mutagens in cervico-vaginal secretions are effective only when activated enzymatically.

J Environ Pathol Toxicol Oncol, 1990 Jul-Oct, 10(4-5), 254 - 9
Detoxification of patulin by adduct formation with cysteine; Lindroth S et al.; Patulin adduct was formed by reacting equimolar amounts of patulin and cysteine at pH 6.0 . The bactericidal effect of the adduct mixture was less than one hundredth of that of free patulin in plate and liquid cultivation tests with Escherichia coli W 3110 thy pol A1 and pol A1+ strains . The bacterial strains did not liberate free patulin from the adduct mixture present in the growth medium . Neither patulin nor the adduct mixture induced repair effects in E . coli . The oral LD50 of patulin for NMRI male mice was 29 mg/kg . For the adduct mixture, not even as high a dose as 2,370 mg patulin equivalents per kg body weight caused any deaths or macroscopic pathological alteration . Neither patulin nor the adduct mixture was mutagenic to the histidine auxotroph Salmonella typhimurium strains TA 100 and TA 98 in microsomal activation tests or to TA 1950 and 1951 in host-mediated assay.

Avian Dis, 1990 Jul-Sep, 34(3), 749 - 53
Intracloacal Salmonella typhimurium infection of broiler chickens: reduction of colonization with anaerobic organisms and dietary lactose; Ziprin RL et al.; The combined effect of treatments with dietary lactose plus anaerobic organisms on cecal colonization of broiler chicks by Salmonella typhimurium was evaluated . Chickens treated with a combination of anaerobic organisms and 7% dietary lactose were resistant to cecal colonization by S . typhimurium . The number of recoverable S . typhimurium cells per gram of cecal contents taken on days 10 and 15 after infection was significantly reduced . Treatment with anaerobes without the addition of lactose did not effectively control cecal colonization . Intracloacal inoculations with bacterial concentrations that varied by 10,000-fold resulted in roughly similar levels of colonization . The treatments resulted in reduced cecal pH and elevated levels of undissociated volatile fatty acids . Statistically significant correlations (P less than 0.01) were observed between the S . typhimurium concentrations in cecal material and the concentrations of undissociated fatty acids (r = -0.79, and between the bacterial counts and pH (r = 0.72).

Avian Dis, 1990 Jul-Sep, 34(3), 668 - 76
Effect of dietary lactose on Salmonella colonization of market-age broiler chickens; Corrier DE et al.; The effect of providing lactose in feed and inoculation with volatile fatty acid-producing anaerobic cultures (AC) of cecal flora on Salmonella typhimurium colonization was evaluated in broilers . One-day-old chicks were divided into four groups and provided 1) no lactose, no AC; 2) AC, no lactose; 3) AC and lactose on days 1-10; or 4) AC and lactose on days 1-40 . All groups were challenged per os with 10(6) Salmonella on day 3 and with 10(8) Salmonella on day 33 . Salmonella growth in the cecal contents was significantly decreased (P less than 0.01) on day 10 in the chicks provided lactose from day 1-10 . However, after the removal of lactose from the diet, the chicks were susceptible to Salmonella colonization . The number of Salmonella in the ceca was significantly reduced (P less than 0.05) in the chicks provided lactose throughout the 40-day growing period . Dietary lactose decreased the pH of the cecal contents and was accompanied by marked increases in the concentrations of undissociated bacteriostatic volatile fatty acids in the cecal contents.

Avian Dis, 1990 Jul-Sep, 34(3), 626 - 33
Biological control of Salmonella typhimurium in young chickens; Hinton A Jr et al.; The effect of dietary lactose and anaerobic cultures of cecal microflora of mature chickens on the colonization of young broiler chickens by Salmonella typhimurium was evaluated . Newly hatched chicks were given either no treatment (controls), anaerobic cecal cultures, lactose (2.5%) in the drinking water, or both anaerobic cultures and lactose . Chicks were challenged per os at 3 days of age with either 10(6) or 10(8) S . typhimurium resistant to nalidixic acid and novobiocin . On day 10, the cecal contents of the chicks were examined for S . typhimurium, pH, short-chained volatile fatty acids (VFAs), undissociated VFAs, and lactic acid . Chicks given either lactose alone or cecal anaerobes alone had significantly (P less than 0.05) fewer S . typhimurium recovered from their ceca than the controls . Chicks given the combination of dietary lactose and cecal anaerobes had significantly fewer S . typhimurium recovered from their ceca than the chicks given dietary lactose or cecal anaerobes alone . Chicks given lactose had significant (P less than 0.05) increases in the lactic acid concentration of their cecal contents . Increased lactic acid concentrations were directly correlated to decreased cecal pH values and caused a reduction in the total concentration of VFAs but a significant (P less than 0.05) increase in the undissociated form of some VFAs.

Avian Dis, 1990 Jul-Sep, 34(3), 617 - 25
Effect of dietary lactose on cecal pH, bacteriostatic volatile fatty acids, and Salmonella typhimurium colonization of broiler chicks; Corrier DE et al.; One-day-old broiler chicks were inoculated with volatile fatty acid producing cecal flora from adult chickens . The chicks were divided into four groups and provided 1) no lactose, 2) 2.5% lactose in water, 3) 5% lactose in feed, or 4) 10% lactose in feed, until 10 days of age . All groups were challenged at 3 days of age with 10(6) or 10(8) S . typhimurium . At 10 days, the number of Salmonella in the ceca of the chicks challenged with 10(6) Salmonella was significantly decreased (P less than 0.01) in the groups provided lactose as compared with the controls . A significant decrease (P less than 0.01) in Salmonella numbers occurred in the chicks challenged with 10(8) Salmonella and provided 10% lactose . Providing 2.5% lactose or 5% lactose failed to inhibit Salmonella growth in chicks challenged with 10(8) Salmonella . The pH of the ceca of the groups provided lactose decreased significantly (P less than 0.05) and was accompanied by significant increases (P less than 0.01) in the concentrations of bacteriostatic acetic and propionic acids . Results showed that providing dietary lactose to broiler chicks and inoculation with normal cecal flora decreased cecal pH, increased the concentrations of bacteriostatic volatile fatty acids, and inhibited Salmonella colonization.

Int J Pept Protein Res, 1990 Jul, 36(1), 1 - 6
Comparisons between the three-dimensional structures of the chemotactic protein CheY and the normal Gly 12-p21 protein; Chen JM et al.; The three-dimensional structure of a chemotactic protein CheY from Salmonella typhimurium has recently been determined by X-ray crystallography . The structure of this small protein, containing 129 amino acid residues, shows a domain consisting of a central beta-pleated sheet surrounded on both sides by alpha-helices . We have examined the sequence and the arrangement of the structural domains of the CheY protein and have compared them with other nucleotide binding protein sequences and structures . We find that the CheY protein has significant sequence homology to the ras-gene encoded p21 protein . In addition, the structural domains of the two proteins are arranged in a fundamentally similar manner, including the phosphate-binding site (both proteins bind phosphate-containing ligands) . The striking similarity in the arrangement of the structural domains of the two proteins suggests that both may serve similar functions as signal transducers.

Mutagenesis, 1990 Jul, 5(4), 307 - 11
Mutagenic evaluation of some triazino indoles using the Salmonella/mammalian microsome assay; Lopez-de-Cerain A et al.; The mutagenicity of ethyl 1,2,3-triazino{5,4-b}indole-4-carboxylate N(3)-oxide (D3) and 2-chloroethyl 1,2,3-triazino-{5,4-b}indole-4-carboxylate N(3)-oxide (D4), heads of series of new products with considerable platelet antiaggregating and hypotensive activity, and their precursors 2-ethoxy-carbonylmethyl-1-methylindole-3-carboxylic acid (A3) and 2-(2-chloroethoxycarbonylmethyl)-1-methylindole-3-carboxylic acid (A4) were tested in four strains of Salmonella typhimurium (TA98, TA100, TA97 and TA102) using the standard plate incorporation technique . A3 and A4 were not mutagenic whereas D3 was mutagenic to all the strains and D4 was mutagenic to TA97, TA98 and TA100 . The addition of 4 or 10% of S9 mix decreased the mutagenic activity of both compounds . This effect was independent of the concentration of S9 in the S9 mix.

Am J Vet Res, 1990 Jul, 51(7), 1095 - 9
Prophylactic effects of recombinant bovine interferon-alpha I1 on acute Salmonella typhimurium infection in calves; Peel JE et al.; The in vivo effects of a single prophylactic dose of recombinant bovine interferon (rBoIFN)-alpha I1 in calves with salmonellosis were investigated, using a Salmonella typhimurium infection model . Treatment with rBoIFN-alpha I1 reduced the degree of septicemia compared with that in control groups, and, in one experiment, using disease of reduced severity, body temperature was lower in treated calves than in controls.

Antimicrob Agents Chemother, 1990 Jul, 34(7), 1444 - 6
Nucleotide sequence of SHV-2 beta-lactamase gene; Garbarg-Chenon A et al.; The nucleotide sequence of plasmid-mediated beta-lactamase SHV-2 from Salmonella typhimurium (SHV-2pHT1) was determined . The gene was very similar to chromosomally encoded beta-lactamase LEN-1 of Klebsiella pneumoniae . Compared with the sequence of the Escherichia coli SHV-2 enzyme (SHV-2E.coli) obtained by protein sequencing, the deduced amino acid sequence of SHV-2pHT1 differed by three amino acid substitutions.

J Vasc Surg, 1990 Jul, 12(1), 16 - 9
Abdominal aortic aneurysms infected with salmonella: problems of treatment; Trairatvorakul P et al.; Seven patients with abdominal aortic aneurysms infected with salmonella organisms were surgically treated between 1985 and 1988 . Salmonella culture was obtained from the wall of the aneurysm in every patient, and in five patients it was identified as Salmonella typhimurium . S . choleraesuis and salmonella group D (isolated from this patient but not speciated) were found in the other two remaining patients . Three patients underwent aneurysmal resection with axillofemoral bypass grafting, and three patients were treated by aneurysmal resection with in situ graft; two of this group had the wall and infective periaortic tissue excised . One patient died during the operation as a result of rupture of the aneurysm . Therapeutic doses of antibiotic drugs were given to all of the patients . Although two of the patients in the first group (with the axillofemoral bypass graft) died and the remaining patient had very complicated postoperative course, all the patients in the second group (with in situ graft) survived . We think that in situ graft placement after an extensive debridement of the aneurysmal wall and infected periaortic tissue together with more effective and adequate antibiotic therapy for at least 6 weeks after the operation is a satisfactory method of surgical treatment of this condition . However, graft infection is still a possibility, therefore regular follow-up is needed.

Mutat Res, 1990 Jul, 241(3), 283 - 90
Mechanism of antimutagenicity of aquatic plant extracts against benzo{a}pyrene in the Salmonella assay; Sato T et al.; The mechanism of antimutagenicity of water extracts of grass-wrack pondweed (Potamogeton oxyphylus Miquel), curled pondweed (Potamogeton crispus L.) and smartweed (Polygonum hydropiper L.) towards benzo{a}pyrene mutagenicity in Salmonella typhimurium was investigated . The antimutagenic components in the aquatic plants were water-soluble, heat-resistant and had a high molecular weight; chlorophyll did not play an important role.

Infect Immun, 1990 Jul, 58(7), 2258 - 61
Moderate immunodeficiency does not increase susceptibility to Salmonella typhimurium aroA live vaccines in mice; Izhar M et al.; Salmonellae carrying appropriate mutations in genes of the aromatic biosynthesis pathway are effective as live vaccines in animals, and they are candidate typhoid vaccines for human use . They are also very effective as carriers of recombinant antigens from other pathogens to the immune system, eliciting circulatory, secretory, and cell-mediated immunity to foreign antigens . Their attenuation is believed to be due to their requirement for the metabolites p-aminobenzoic acid and 2,3-dihydroxybenzoate, which are not available in mammalian tissues . Immunosuppression (e.g., acquired immunodeficiency syndrome) is a major contraindication to the use of live vaccines . If the avirulence of Aro mutants is largely due to their auxotrophy, they should not be markedly more invasive in immunosuppressed animals . We report that wild-type Salmonella typhimurium M525 of intermediate virulence was much more invasive in sublethally irradiated BALB/c mice than in normal BALB/c mice, whereas sublethal irradiation had little if any effect on the invasiveness of an S . typhimurium aorA vaccine strain apart from a delay in its clearance from the reticuloendothelial system . xid mutant CBA/N mice carry an X-linked B-cell functional defect which results in immunoglobulin G3 agammaglobulinemia, and they are known to be more susceptible to salmonellae in late stages of the infection . We found that whereas male (CBA/N x BALB/c)F1 mice (immunodefective) were more susceptible to wild-type S . typhimurium C5 than female littermates (immunocompetent), there was no difference in the response to the S . typhimurium aroA vaccine strain . The results indicate that moderate immunosuppression does not markedly enhance susceptibility to S . typhimurium aroA live vaccines.

J Exp Med, 1990 Jul 1, 172(1), 77 - 84
Lipid IVA inhibits synthesis and release of tumor necrosis factor induced by lipopolysaccharide in human whole blood ex vivo; Kovach NL et al.; Tumor necrosis factor (TNF) released by lipopolysaccharide (LPS)-stimulated mononuclear phagocytes is a critical mediator of sepsis . We examined the capacities of rough mutant Salmonella typhimurium LPS (Rc) and LPS partial structures lipid A, monophosphoryl lipid A (MPLA), lipid IVA, and lipid X to induce production of TNF in whole blood . Rc LPS (0.0001-10 ng/ml) produced a dose-dependent release of TNF as determined by cytotoxicity of actinomycin D-sensitized L929 murine fibroblasts . Lipid A, MPLA, lipid IVA, and lipid X exhibited decreasing capacities to stimulate production of TNF in whole blood, respectively . Fractional deacylation of LPS by incubation with acyloxyacyl hydrolase isolated from human leukocytes produced a reduction in the capacity of LPS to induce TNF release in whole blood . Maximal enzymatic deacylation reduced activity of LPS by greater than 100-fold . Coincubation with lipid IVA inhibited TNF release induced by Rc LPS or lipid A, but not by phorbol ester . In contrast, MPLA, lipid X, and deacylated LPS failed to inhibit LPS-stimulated release of TNF . Corresponding to the inhibition of the release of TNF protein, lipid IVA also inhibited the accumulation of TNF mRNA in LPS-stimulated mononuclear cells . These results suggest that lipid IVA may act as a competitive antagonist of LPS, perhaps at the receptor level.

Antimicrob Agents Chemother, 1990 Jul, 34(7), 1323 - 5
Activity of KB-5246 against outer membrane mutants of Escherichia coli and Salmonella typhimurium; Kotera Y et al.; The inhibitory activity of KB-5246 against Escherichia coli DNA gyrase and the antibacterial activity and apparent uptake in E . coli and Salmonella typhimurium outer membrane mutants of KB-5246 were measured . The 50% inhibitory concentrations of KB-5246, ciprofloxacin, oflaxacin, and norfloxacin for E . coli KL-16 DNA gyrase were 0.72, 0.62, 0.84, and 1.16 micrograms/ml, respectively . The activity of KB-5246 was twofold lower against an OmpF-deficient mutant and twofold higher against a mutant which produced OmpF constitutively than against the parent with osmoregulated OmpF production . KB-5246 had twofold-higher activity against a deep rough mutant of S . typhimurium than against the parent . The apparent uptake of KB-5246 in the OmpF-deficient mutant was decreased and its uptake in the deep rough mutant was increased when compared with those in the parents . These results suggest that KB-5246 is taken up by porin and nonporin pathways and has strong inhibitory activity against DNA gyrase, resulting in potent antibacterial activity.

J Bacteriol, 1990 Jul, 172(7), 4100 - 2
Identification and cloning of genes involved in anaerobic sulfite reduction by Salmonella typhimurium; Huang CJ et al.; Transposon Tn5 insertions causing anaerobic cysteine auxotrophy were isolated from a Salmonella typhimurium cysI parent (auxotrophic under aerobic but not anaerobic conditions) . Insertions in one mutant group appeared to be in cysG . A second group of insertions, designated asr (anaerobic sulfite reduction), were located near map unit 53 on the S . typhimurium chromosome . They did not cause aerobic or anaerobic auxotrophy in a cys1+ background but did prevent dissimilatory sulfite reduction . Plasmids containing asr DNA cloned from wild-type S . typhimurium conferred anaerobic prototrophy and the ability to produce hydrogen sulfide from sulfite on an Escherichia coli cys1 mutant.

Cesk Epidemiol Mikrobiol Imunol, 1990 Jul, 39(4), 242 - 9
{The plasmid profile of Salmonella typhimurium strains untypable by phages}; Majtanova L et al.; The authors examined 250 strains of Salmonella typhimurium, untypable by phagi, for the sensitivity to antibacterial substances and lysogeny . Testing of the sensitivity to a set of 13 antibacterial substances revealed that 157 strains (63%) were polyresistent . Most frequently they were resistent to ampicillin (96% strains), sulphamethoxydine (71.2%), carbenicillin (68% strains), tetracycline (56% strains), cephalotine (56%), chloramphenicol (53%) and septrin (51% strains) . The presence of a prophage was revealed in 99.2% strains . In a narrower selection of 54 strains plasmid DNA was isolated and electrophoretic analysis revealed the presence of 1-5 plasmids . Six strains were plasmid-free . The magnitude of plasmids varied between 2 and 41.4 kb . The authors indicate possibilities of using the plasmid profile in the differentiation of strains.

Infect Immun, 1990 Jul, 58(7), 2048 - 55
Oral immunization of mice with attenuated Salmonella typhimurium containing a recombinant plasmid which codes for production of a 31-kilodalton protein of Brucella abortus; Stabel TJ et al.; Salmonella typhimurium chi 4064, an attenuated delta cya delta crp mutant of S . typhimurium SR-11, was used as a carrier for the plasmid pBA31-R7 . This plasmid codes for the expression of a 31-kilodalton (kDa) protein from Brucella abortus (BCSP31) . Recombinant S . typhimurium chi 4064(pBA31-R7) expressed BCSP31 in vitro as shown by Western blot (immunoblot) analysis . The plasmid was stable in vitro and in vivo and did not affect the ability of the mutant to invade and colonize the small intestine, mesenteric lymph nodes, liver, or spleen of BALB/cByJ mice . Animals orally immunized with S . typhimurium chi 4064(pBA31-R7) developed serum and intestinal antibody responses to the B . abortus 31-kDa protein and to salmonella endotoxin as measured by enzyme-linked immunosorbent assay . Mice orally immunized with S . typhimurium chi 4064pBA31-R7 did not develop a delayed-type hypersensitivity following a footpad injection with recombinant BCSP31 . Antigen-specific blastogenic data also support these in vivo results . All data indicate that this route of antigen delivery is effective for stimulating antibody-mediated immunity but that the B . abortus 31-kDa protein is a poor immunogen for inducing a cell-mediated immune response in BALB/cByJ mice.

Rev Inst Med Trop Sao Paulo, 1990 Jul-Aug, 32(4), 269 - 74
Screening the mutagenic activities of commonly used antiparasite drugs by the Simultest, a simplified Salmonella/microsome plate incorporation assay; Melo ME et al.; The mutagenic activities of 16 anti-parasite drugs were screened by the Simultest in both qualitative (spot test) and quantitative (plate incorporation) assays with a Salmonella typhimurium pool composed by the indicator strains TA97, TA98, TA100 and TA102 . Four anti Chagas' disease drugs (nifurtimox, benznidazole, CL 64,855, and MK 436) and two anti-amebae drugs (metronidazole and tinidazole) gave positive results in qualitative tests and incorporation of rat liver microsomes did not alter the results . Comparative dose response curves of the mutagenic activities of CL 64,855, metronidazole and benznidazole obtained by the simultest and by individual Salmonella indicator strains demonstrated that both approaches have similar sensitivities . The results corroborate the validity of the Simultest, as a simplified, fast and economic version of the Ames test in preliminary screening of potential mutagenic drugs.

Microb Pathog, 1990 Jul, 9(1), 47 - 53
Effect of motility and chemotaxis on the invasion of Salmonella typhimurium into HeLa cells; Khoramian-Falsafi T et al.; Salmonella typhimurium strain LT2 is able to invade HeLa cells in vitro . The effect of the motility and chemotaxis of the bacteria on cell invasion were examined by two methods: (1) conventional invasion assays where the HeLa cell monolayers were placed horizontally at the bottom of plastic wells and (2) vertical assays where the HeLa cell monolayer attached to one face of plastic bottles was placed vertically . In both assays, the invasion rate of the wild-type strain was higher than that in isogenic non-motile mutants . There was no significant difference between the invasion rate of non-flagellated mutants and that of a flagellated but non-motile mutant . These observations indicated that the motility per se increases the rate of the bacterial invasion by increasing the chance of encounter between Salmonella and the HeLa cells . Smooth-swimming non-chemotactic mutants exhibited 10 times higher invasion rates than the wild-type strain in conventional assays but their invasion rates in vertical assays were approximately equal to that of the wild-type strain . This result indicated that in the conventional assays, the migration of the wild-type bacteria towards the HeLa cells was hampered by their chemotactic responses . Tumbly non-chemotactic mutants exhibited invasion rates intermediate between the wild-type and non-motile strains presumably because of their intermediate net speeds of migration.

Res Rep Health Eff Inst, 1990 Jul, (34), 1 - 30
Metabolic activation of nitropyrenes and diesel particulate extracts; Jeffrey AM et al.; The aim of this research was to investigate the possible risks of genotoxicity associated with human exposure to diesel engine emissions . We sought to identify and evaluate the critical components of such emissions by using a variety of short-term biological systems . Adducts formed between benzo{a}pyrene and DNA in several short-term test systems have been thoroughly investigated . Although benzo{a}pyrene has long been used as an index of the potential carcinogenicity of polycyclic aromatic hydrocarbon mixtures and is present in diesel engine emissions, it may not be the best measure of the carcinogenicity of these emissions if, indeed, they are confirmed to exert such an effect in humans . Certain nitroarenes, known to be present in diesel particulate extracts, are very potent mutagens in the Ames assay . The major adducts formed in Salmonella typhimurium with 1-nitropyrene (Howard and Beland 1982) and 1,8-dinitropyrene (Andrews et al . 1986; Fifer et al . 1986) have been identified . We undertook, therefore, a comparison of the DNA adducts formed between 1-nitropyrene, 1,3-dinitropyrene, 1,6-dinitropyrene, and 1,8-dinitropyrene and cellular DNA in various systems, including human bronchial segments, in rabbit lung and trachea, and mouse embryo fibroblast C3H/10T1/2 cells, with those reported to be formed in S . typhimurium . In these studies, we administered radiolabeled nitropyrenes, analogous to the treatments previously employed for testing benzo{a}pyrene, and isolated and digested the modified DNA . We then compared elution times, by high-pressure liquid chromatography, of the radioactive adducts with synthetic standards . Not all combinations of exposures were undertaken, since the direction of the investigations changed to include studies on adducts formed in animals exposed to diesel engine emissions themselves . Of the samples studied, metabolism of 1-nitropyrene was most evident in the human bronchial tissue . Little metabolism was evident in duodenal and colonic samples . Mouse C3H/10T1/2 embryo fibroblasts showed no detectable metabolism of, DNA adduct formation with, or transformation by 1-nitropyrene . DNA adducts were detected in cells exposed to 1,8-dinitropyrene and traces of adducts were formed with either 1,3-dinitropyrene or 1,6-dinitropyrene . Measurements of DNA adducts formed after treatment with {4,5,9,10-3H}-1-nitropyrene in rabbit tracheal samples showed that only about 2 to 15 percent of the associated radiolabel could be accounted for as the previously identified C-8 adduct . To facilitate the quantification of adduct levels that might occur in humans and laboratory animals exposed to the nitroarenes in diesel engine emissions, antisera were prepared against DNA modified with 1-nitrosopyrene.(ABSTRACT TRUNCATED AT 400 WORDS)

Biochem Biophys Res Commun, 1990 Jun 29, 169(3), 1094 - 8
Synthesis and properties of vinyl carbamate epoxide, a possible ultimate electrophilic and carcinogenic metabolite of vinyl carbamate and ethyl carbamate; Park KK et al.; Vinyl carbamate reacted with dimethyldioxirane in dry acetone to give a high yield of pure crystalline vinyl carbamate epoxide . This epoxide was characterized by its NMR and MS spectra and elementary analysis . It is unstable at room temperature and has a half-life in water solution of approximately 32 minutes . It reacts with adenosine to form 1,N6-ethenoadenosine and more of this etheno nucleoside was found in hydrolysates of hepatic RNA of male mice injected i.p . with the epoxide than with vinyl carbamate . Tests with Salmonella typhimurium TA1535 showed that this epoxide is a strong direct mutagen . It is also more toxic in the mouse than vinyl carbamate . Studies on the carcinogenicity of this epoxide are in progress.

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