J Dairy Sci, 1989 Dec, 72(12), 3166 - 75 Lactoferrin and lysozyme in milk during acute mastitis and their inhibitory effect in Delvotest P; Carlsson A et al.; Microbiological methods for detection of antibiotic residues in milk give no explanations regarding the identity of the inhibitory substance(s) . Natural antibacterial substances, present at higher concentrations in mastitic milk and in colostrum, occasionally cause false positive results in antibiotic assays . In an earlier investigation, lysozyme and lactoferrin were shown to inhibit the growth of Bacillus stearothermophilus var . calidolactis spores, used as test organism in Delvotest P . To study the effect of high lysozyme and lactoferrin concentrations in milk on the Delvotest P, cows were subjected to acute experimental mastitis by infusion of Salmonella typhimurium SH 4809 endotoxin . Milk samples were collected up to 11 h postinfusion . Concentrations of lactoferrin and lysozyme, somatic cell count, and effect on Delvotest P were determined . A positive reaction in the Delvotest correlated well with an increase in lactoferrin and lysozyme concentrations . The nature of the inhibitory effect is briefly discussed. FEMS Microbiol Immunol, 1989 Dec, 1(8-9), 485 - 90 Immunogenic endotoxin associated protein from a rough strain of Salmonella; Phillips M et al.; A multimolecular complex of polypeptides found associated with the lipopolysaccharide endotoxin in Salmonella, referred to as endotoxin-associated protein (EP), has been extracted from a rough strain of Salmonella typhimurium which does not synthesize 0 antigens . Since standard methods of extraction applicable to smooth strains of Salmonella were not successful for this rough strain, two modified procedures were developed . The resulting products were similar to smooth EP in terms of their biochemical, physical and mitogenic properties . When the immunogenicity of the rough EP was characterized by a protection assay in mice challenged with virulent Salmonella, it was found that the rough EP preparations were protective; however, they were not as active as the EP from a smooth strain of S . typhimurium. APMIS, 1989 Dec, 97(12), 1114 - 20 Protective properties of a human IgG preparation rich in antibodies to a wide spectrum of lipopolysaccharides; Fomsgaard A et al.; Naturally occurring human IgG, rich in antibodies to different lipopolysaccharides was investigated for possible protective effects against lethal endotoxin shock and lethal gram-negative infection in mice . The IgG preparation was obtained from pooled serum of selected blood donors with high concentrations of antibodies to 11 different LPS as measured by ELISA . The human IgG (5 mg/mouse) protected C3H/TifF mice against an otherwise lethal infection with Salmonella typhimurium . The human IgG also inhibited the lethality induced by purified LPS in D-galactosamine sensitized C57B1/6 mice . The protection was dependent on the IgG dose given . However, protection was not obtained against all the LPS preparations tested . Absorption of the IgG with different LPS, showed the protection to be caused by serotype-specific anti-LPS antibodies . Protection against a given LPS was not related directly to the corresponding anti-LPS titer as measured by ELISA and passive hemolysis . The interpretation of these results is discussed. J Immunol, 1989 Dec 1, 143(11), 3703 - 7 Regulated expression of proenkephalin A in normal lymphocytes; Rosen H et al.; The expression of proenkephalin A (PEA), a neuropeptide-encoding gene, was examined in normal rat lymphocytes . With the use of Northern blot hybridization analysis of total RNA, PEA mRNA was found in normal cells derived from spleen, lymph nodes, and bone marrow . Cell sorting of the two main fractions of B and T cells derived from the spleen revealed that PEA is expressed in normal B cells (sIg+) . The expression of PEA mRNA was markedly enhanced after a short incubation (3 h) of cells with LPS or Salmonella typhimurium . This was not the case when these cells were incubated with Con A during the same period of time; whereas, in thymocytes the presence of PEA mRNA was exclusively dependent upon mitogenic stimulus (Con A) and could be detected after 24 h of in vitro incubation . Extracts of cells were also found to contain immune reactive enkephalins, indicating that the PEA mRNA is translated . These results support the concept that neuropeptides, such as enkephalins, have a role in the modulation of the immune response and may participate in the bidirectional communication between the nervous and immune systems. Genetics, 1989 Dec, 123(4), 625 - 33 Genetic analysis of temperature-sensitive lethal mutants of Salmonella typhimurium; Schmid MB et al.; We have isolated 440 mutants of Salmonella typhimurium that show temperature-sensitive growth on complex medium at 44 degrees . Approximately 16% of the mutations in these strains have been mapped to 17 chromosomal locations; two of these chromosomal locations seem to include several essential genes . Genetic analysis of the mutations suggests that the collection saturates the genes readily mutable to a ts lethal phenotype in S . typhimurium . Physiological characteristics of the ts lethal mutants were tested: 6% of the mutants can grow at high temperature under anaerobic conditions, 17% can grow when the medium includes 0.5 M KCl, and 9% of the mutants die after a 2-hr incubation at the nonpermissive temperature . Most ts lethal mutations in this collection probably affect genes required for growth at all temperatures (not merely during high temperature growth) since Tn10 insertions that cause a temperature-sensitive lethal phenotype are rare. FASEB J, 1989 Dec, 3(14), 2574 - 82 Bacterial adaptation to oxidative stress: implications for pathogenesis and interaction with phagocytic cells; Hassett DJ et al.; During phagocytosis, phagocytic cells generate superoxide and other reactive oxygen species, which are involved in antibacterial activity . However, many bacteria possess antioxidant defenses that may explain their survival in inflammatory foci . These defenses include antioxidant enzymes such as superoxide dismutase and catalase, DNA repair systems, scavenging substrates, and competition with phagocytes for molecular oxygen . These defenses are probably coordinated, and different responses occur with different reactive oxygen species . Escherichia coli and Salmonella typhimurium mutants have allowed the demonstration of a variety of critical genes for enzymatic defense and DNA repair, as well as an oxyR regulon system . In more complex systems, the conditions found in inflammatory foci, such as decreasing glucose and the production of lactate, enhance bacterial catalase production and resistance to hydrogen peroxide . Resistance and adaptation to phagocyte-derived oxidant stress are critical aspects of bacterial pathogenesis. Immunol Lett, 1989 Dec, 23(2), 125 - 32 Immunological functions in food-restricted rats: enhanced expression of high-affinity interleukin-2 receptors on splenic T cells; Iwai H et al.; Several immunological functions of B and T cells including IL-2 receptor expression on T cells were measured in 12-month-old Fisher-344 male rats maintained from 6 weeks of age on an ad libitum (AL) or a 40% food-restricted (FR) diet . Direct anti-SRBC plaque-forming cell (PFC) assays revealed a higher response in FR rats than in AL rats when splenocytes were cultured with or without recombinant interleukin-2 (rIL-2) . B cell functions were studied by using nylon wool-purified splenic B cells stimulated either with rIL-2, lipopolysaccharide (LPS), or Salmonella typhimurium mitogen (STM) as a thymus-independent antigen . Reserve plaque assay showed no difference between FR and AL rats in the secretion of anti-IgM and anti-IgG antibodies . In addition, no difference was found in proliferation of B cells stimulated by LPS, STM mitogens or rIL-2 . Although purified splenic T cells demonstrated an equally proliferative response in FR and AL rats when cultured with concanavalin A (Con A) or phytohemagglutinin (PHA), T cells in FR rats developed higher responses when stimulated with an alloantigen and rIL-2 . Time-course studies carried out to measure high-affinity (HA) IL-2 receptor (R) molecules by using purified T cells with rIL-2 and 125I-labeled IL-2 revealed a higher expression of IL-2R molecules on T cells of FR rats than on T cells of AL rats at 72 h after culturing with Con A.(ABSTRACT TRUNCATED AT 250 WORDS) J Cell Biol, 1989 Dec, 109(6 Pt 1), 2771 - 82 The opsonizing ligand on Salmonella typhimurium influences incorporation of specific, but not azurophil, granule constituents into neutrophil phagosomes; Joiner KA et al.; Phagosomes were purified from human neutrophils ingesting Salmonella typhimurium opsonized with adsorbed normal human serum or with rabbit IgG . Constituents within the phagosome were endogenously labeled by supplying the cells with 125INa during phagocytosis . Lactoferrin and vitamin B12 binding protein (TC1 and TC3), markers for specific granules, were present in the phagosomes from neutrophils ingesting S . typhimurium opsonized with IgG but were 3.5- to 5-fold less prominent in phagosomes from cells phagocytosing Salmonella bearing C3 fragments only . In contrast, iodinated azurophilic granule components, most prominently defensins, were the major constituents in phagosomes prepared under both opsonization conditions . Furthermore, labeled complement (CR1 and CR3) and immunoglobulin (Fc gamma RIII) receptors were incorporated in the phagosome regardless of the ligand mediating phagocytosis . These results suggest that the ligand-receptor interactions mediating phagocytosis influence incorporation of neutrophil-specific granule contents into phagosomes. Infect Immun, 1989 Dec, 57(12), 3894 - 900 O antigen and lipid A phosphoryl groups in resistance of Salmonella typhimurium LT-2 to nonoxidative killing in human polymorphonuclear neutrophils; Stinavage P et al.; We have compared the intraleukocytic survival of isogenic strains of Salmonella typhimurium, whose outer membrane lipopolysaccharide differed in O antigen and lipid A composition and whose susceptibility to nonoxidative antimicrobial granule proteins of human polymorphonuclear neutrophilis (PMN) could be established . We found that the order of resistance to the bactericidal activity of intact PMN of the three bacterial strains utilized closely resembled their ordered resistance to the purified human cationic antimicrobial 57,000-dalton protein (CAP57) . LT-2, a smooth wild-type strain, was far more resistant than SH9178, its rough (Rb LPS) mutant . It was most significant that SH7426, a polymyxin B-resistant pmrA mutant of SH9178, not only was substantially more resistant to CAP57 and to intraphagocytic killing than SH9178 but also came close to being as resistant as LT-2 . These experiments confirm earlier work that showed the importance of the glycosyl groups of O antigens of S . typhimurium for their resistance to O2-independent antimicrobial phagocytosis by PMN . The surprising result was that a rough strain, very susceptible to bactericide, became substantially more resistant when a mutation led to its lipid A phosphoryl groups being 100% substituted with amino pentoses . Yet unresolved is whether the protection is due to the loss of negative charges on the lipid A, the substitution of sugar molecules in vulnerable loci in the outer membrane, or both. Gene, 1989 Nov 30, 83(2), 197 - 206 Comparative analysis of the Salmonella typhi and Escherichia coli ompC genes; Puente JL et al.; The nucleotide (nt) sequence of the gene encoding the Salmonella typhi OmpC outer membrane protein, and its deduced amino acid (aa) sequence are presented here . The S . typhi ompC gene consists of an open reading frame of 1134 nt, corresponding to a protein of 378 aa; with a 21-aa signal peptide . This protein is 11 aa longer than Escherichia coli OmpC, but it has an identical leader peptide . The mature OmpC sequence shows 79% similarity for both bacteria at the aa level, and 77% similarity at the nt level . Seven main variable regions in the OmpC protein were identified . Five of them correspond to hydrophilic regions and contain aa observed most frequently in turn configurations in soluble proteins . This suggests that these aa stretches could be located on the exterior of the outer membrane . To probe into the genus and species specificity of the main variable regions, we have constructed complementary oligodeoxyribonucleotides . The use of one of them with a small number of DNA samples is illustrated here; no restriction fragment length polymorphism or nt sequence heterogeneity could be found between S . typhi and Salmonella typhimurium. J Immunol Methods, 1989 Nov 30, 124(2), 267 - 75 Oxygen-independent antimicrobial action in sphingosine-treated neutrophils; Stinavage P et al.; Sphingosine is reported to inhibit the oxidative burst and superoxide anion production of human polymorphonuclear neutrophils (PMN) phagocytosing in atmospheric oxygen (Wilson et al., 1986) . We have confirmed its effect on superoxide production and examined the antimicrobial phagocytic capacity of PMN treated with sphingosine, comparing them with PMN, untreated but phagocytosing either under anaerobic conditions or in atmospheric oxygen . Sphingosine just like anaerobiosis partially inhibited, but did not eliminate, the bactericidal activity of PMN when compared to non-treated aerobic cells . In fact, sphingosine-treated PMN mimicked killing of Staphylococcus aureus (S . aureus) and Serratia marcescens (S . marcescens) due to anaerobic PMN . Moreover, our results with Salmonella typhimurium and sphingosine-treated cells duplicated results this laboratory published previously about comparative killing of Salmonella in aerobic versus anaerobic neutrophils . In these studies sphingosine-treated PMN took up bacteria as avidly as untreated PMN and retained their viability, as assessed by trypan blue exclusion . While sphingosine should not be completely substituted for anaerobic studies, it is a convenient screening reagent for the study of non-oxidative killing mechanisms of PMN . Results achieved with anaerobic and with sphingosine-treated cells suggest that O2-independent antimicrobial action is substantially more powerful than has been generally acknowledged. J Biol Chem, 1989 Nov 25, 264(33), 20112 - 9 Characterization of bacteriophage P22 tailspike mutant proteins with altered endorhamnosidase and capsid assembly activities; Schwarz JJ et al.; The tailspike protein of Salmonella typhimurium phage P22 is a multifunctional homotrimer which is involved in the terminal reaction of phage assembly, the adsorption of the phage to susceptible cells, and the hydrolysis of the Salmonella O-antigen during the first steps of phage infection . The proteins made from 15 mutant tailspike structural genes carried on high level expression plasmids have been analyzed with respect to their in vivo stability, quaternary structure, capsid assembly activity, and enzymatic activity . Nine mutants synthesize tailspike proteins which fail to accumulate to any appreciable level in vivo, and thus these proteins are probably degraded . Four other altered proteins accumulate in vivo as soluble monomers . The remaining two altered proteins accumulate in vivo as stable trimers . Each of these two proteins is defective for at least one of the known functions of the tailspike protein . One is defective in the capsid assembly reaction and shows an unusual quaternary structural defect but is normal with respect to the enzymatic hydrolysis of O-antigen . The other is defective in the enzymatic hydrolysis of O-antigen but is normal with respect to its capsid assembly activity and quaternary structure . The known sequence changes which give rise to these altered proteins and those of previously identified mutants allow the description of possible functional and structural "domains" of this multifunctional protein. Nature, 1989 Nov 23, 342(6248), 396 - 401 The barrier to recombination between Escherichia coli and Salmonella typhimurium is disrupted in mismatch-repair mutants; Rayssiguier C et al.; The requirement for DNA sequence homology in generalized genetic recombination is greatly relaxed in bacterial mutL, mutS and mutH mutants deficient in mismatch repair . In such mutants, intergeneric recombination occurs efficiently between Escherichia coli and Salmonella typhimurium, which are approximately 20% divergent in DNA sequence . This finding has implications for speciation, for regulating recombination between diverged repeated sequences, and for hitherto difficult interspecies hybridizations. Eur J Biochem, 1989 Nov 20, 185(3), 541 - 6 rfaP mutants of Salmonella typhimurium; Helander IM et al.; Salmonella typhimurium rfaP mutants were isolated and characterised with respect to their sensitivity towards hydrophobic antibiotics and detergents, and their lipopolysaccharides were chemically analysed . The rfaP mutants were selected after diethylsulfate mutagenesis or as spontaneous mutants . The mutation in two independent mutants SH7770 (line LT2) and SH8551 (line TML) was mapped by cotransduction with cysE to the rfa locus . The mutants were sensitive to hydrophobic antibiotics (clindamycin, erythromycin and novobiocin) and detergents (benzalkoniumchloride and sodium dodecyl sulfate) . Analysis of their lipopolysaccharides by chemical methods and by sodium dodecyl sulfate/polyacrylamide gel electrophoresis revealed that their saccharide portion was, to a large extent, of chemotype Rc with small proportions of material containing a more complete core oligosaccharide and O-specific chains . Only 2.5 mol phosphate/mol lipopolysaccharide was found whereas the phosphate content of the lipopolysaccharide of a galE mutant strain was 4.8 mol . Thus the rfaP mutant lipopolysaccharides lacked more than two phosphate residues . Assessment of the location of phosphate groups in rfaP lipopolysaccharides revealed the presence of at least 2 mol phosphate in lipid A, indicating that the core oligosaccharide was almost devoid of phosphate . The chemical, physiological and genetic data obtained for these mutants are in full agreement with those reported earlier for rfaP mutants of Salmonella minnesota. Gene, 1989 Nov 15, 83(1), 95 - 103 Human metallothionein-II is synthesized as a stable membrane-localized fusion protein in Escherichia coli; Jacobs FA et al.; A synthetic gene encoding human metallothionein-II (HMT) was cloned into the specially constructed high-copy-number expression vector, pUA7, and expressed in Escherichia coli . The plasmid construct includes the promoter/operator and regulatory sequences of the Salmonella typhimurium ara operon and part of the 5'-coding and all of the 3'-noncoding regions of the E . coli lpp . Upon induction with arabinose, the resulting Lpp::HMT fusion protein was produced 75,000-fold over uninduced cells, with a relatively stable mRNA (T1/2 of 8.3 min) and a completely stable protein . In addition, over 95% of the final fusion protein was localized in the outer membrane and was capable of binding heavy metals (especially cadmium) in vitro . Cells producing Lpp::HMT bioaccumulated heavy metals (e.g., cadmium) 66-fold over nonproducing cells. J Natl Cancer Inst, 1989 Nov 15, 81(22), 1743 - 7 Inhibition by diacylmethane derivatives of mutagenicity and nucleic acid binding of 2-aminofluorene derivatives; Wang CY et al.; The active methylene compounds acetylacetone, 1,1,1-trifluoroacetylacetone, benzoylacetone, dibenzoylmethane, and 1,3-indandione inhibited the mutagenicity of 2-nitrofluorene in Salmonella typhimurium . They also inhibited the N,O-acetyltransferase-catalyzed transfer RNA binding of N-hydroxy-2-acetylaminofluorene, but they did not inhibit N,O-acetyltransferase . However, only 1,3-indandione and 1,1,1-trifluoroacetylacetone significantly inhibited the binding of N-acetoxy-2-acetylaminofluorene to transfer RNA . Reaction of the trifluoro compound with the acetoxy compound yielded 1-(N-2-fluorenylacetamido)acetone . These results demonstrate that active methylene compounds can inhibit mutagenicity and nucleic acid binding of chemical carcinogens. Cancer Res, 1989 Nov 15, 49(22), 6304 - 12 Roles of individual human cytochrome P-450 enzymes in the bioactivation of benzo(a)pyrene, 7,8-dihydroxy-7,8-dihydrobenzo(a)pyrene, and other dihydrodiol derivatives of polycyclic aromatic hydrocarbons; Shimada T et al.; Human liver microsomes oxidized 7,8-dihydroxy-7,8-dihydrobenzo(a)pyrene {B(a)P-7,8-diol} to products that yield DNA adduct formation and umu gene expression in the tester system Salmonella typhimurium TA1535/pSK1002 . The umu response is correlated to levels of microsomal cytochrome P-450NF (P-450NF) and nifedipine oxidation in different human liver samples used for activation, and both the (+)- and (-)-enantiomers of B(a)P-7,8-diol gave similar results in these and other assays . The microsomal umu response was inhibited by antibodies raised against P-450NF . 7,8-Benzoflavone stimulated the B(a)P-7,8-diol-dependent umu response observed with purified P-450NF and human liver and lung microsomes . Thus, P-450NF appears to be the major enzyme involved in the activation of B(a)P-7,8-diol in human liver and possibly lung . Similar results were obtained for the activation of trans-9,10-dihydroxy-9,10-dihydrobenzo(b)fluoranthene and trans-3,4-dihydroxy-3,4-dihydro-7,12-dimethylbenz(a)anthracene, compounds that are known to form highly tumorigenic diol-epoxides . The major product of the oxidation of (+)-B(a)P-7,8-diol was the cis-syn isomer of benzo(a)pyrene-7,8,9,10-tetraol{7 beta, 8 alpha, 9 beta, 10 beta-tetrahydroxy-7,8,9,10-tetrahydrobenzo(a)pyrene} . Studies on the nature of the human liver enzymes involved in the formation of B(a)P-7,8-diol {from benzo(a)pyrene} indicate that neither P-450NF, P-450PA, P-450j, P-450DB, nor P-450MP is involved . The correlation of 7,8-diol formation with phenacetin O-deethylation in a set of liver samples and the partial inhibition of the reaction by 7,8-benzoflavone and anti-rat P-450 beta NF-B suggest that the enzyme involved may be P1-450, the human ortholog of rat P-450 beta NF-B, which catalyzes both the formation of B(a)P-7,8-diol and its subsequent oxidation in tissues of polycyclic hydrocarbon-treated rats . The differential effects of inhibitors indicate that benzo(a)pyrene 3-hydroxylation, 4,5-epoxidation, and 9,10-epoxidation are catalyzed by an enzyme(s) distinct from that which forms the 7,8-epoxide . The roles of the human P-450 enzymes differ from the rodent orthologs in the paradigm for bioactivation of polycyclic hydrocarbons; further, flavones appear to have opposing effects on diol formation and further epoxidation in both human liver and lung. FEBS Lett, 1989 Nov 6, 257(2), 274 - 8 Molecular organization of genes constituting the virulence determinant on the Salmonella typhimurium 96 kilobase pair plasmid; Taira S et al.; The ability of intracellular growth is plasmid-dependent in Salmonella typhimurium . Only a small portion of this 96 kilobase pair plasmid appears essential for intracellular growth . The genetic organization of this region (the essential virulence determinant) was resolved . Fragments of the virulence determinant were cloned from the 96-kb plasmid pEX102 and transformed into minicell-producing E . coli . Plasmid-directed protein synthesis was investigated in metabolically labeled minicells . This analysis indicated the presence of at least four genes, mkaA, mkaB, mkaC and mkaD, within the virulence determinant encoding proteins of 70, 31, 30 and 29 kDa, respectively . The genes were positioned on the restriction map of the 96-kb virulence plasmid and the map locations confirmed by nucleotide sequence analysis of two new virulence genes (mkaB and mkaC). Eur J Biochem, 1989 Nov 6, 185(2), 319 - 25 Studies on the domain structure of the Salmonella typhimurium AraC protein; Lauble H et al.; The Salmonella typhimurium araC gene product is known to be susceptible to proteolytic degradation . Limited cleavage by trypsin, kallikrein, elastase and pronase E yields stable fragments comprising approximately the N-terminal two thirds of the AraC protein . These fragments have in common the ability to dimerize in solution and to bind L-arabinose and D-fucose . Under appropriate conditions, hydrolysis of the AraC protein with Staphylococcus aureus V8 protease leads to a small C-terminal fragment which is able to bind specifically to a synthetic ara consensus sequence . These results indicate that, as with several other prokaryotic gene regulatory proteins, the basic functions of effector binding, subunit interaction and specific DNA binding are segregated into distinct domains of the AraC protein. Photochem Photobiol, 1989 Nov, 50(5), 625 - 32 Singlet oxygen induced mutagenesis of benzo{a}pyrene derivatives; Seed JL et al.; Singlet oxygen activates the mutagenicity of several benzo{a}pyrene (BP) derivatives in the absence of mammalian metabolic action . This has been demonstrated using a separated-surface-sensitizer system for generating chemically pure singlet oxygen, eliminating most of the complications that arise with singlet oxygen generation by conventional photosensitization . Salmonella typhimurium bacteria were exposed to singlet oxygen in the presence of certain BP derivatives and the mutation frequency determined with an azaguanine forward mutation assay . The mutation frequency was increased by exposure to singlet oxygen compared to light-only controls for those BP derivatives that were saturated at either the 7,8 or 9,10 positions but not both . The increase in mutation frequency depends on both the concentration of BP derivative and on the dose of singlet oxygen . Mutation frequency was also significantly increased when bacteria were treated with a solution of trans-7,8-dihydrodiol-BP that had been separately exposed to singlet oxygen, unequivocally demonstrating that the mutagenicity is due to the formation of a product of BP derivative oxidation by singlet oxygen and that this product has a lifetime at least on the order of minutes in acetonitrile . The requirement for singlet oxygen rather than some other form of reactive oxygen was confirmed by determination of the gas phase lifetime of the intermediate responsible for activating mutagenicity . This was performed by measuring the dependence of the mutation frequency on the distance separating the sensitizer from the target . This gives a value of 88 +/- 35 ms, which is in excellent agreement with the mean value of 89 ms calculated from previous independent determinations of the gas phase lifetime of singlet oxygen reported in the literature. Mutagenesis, 1989 Nov, 4(6), 453 - 5 Re-evaluation of the effect of ellagic acid on dimethylnitrosamine mutagenicity; Lord HL et al.; Dimethylnitrosamine (DMN) is activated to mutagenic species in the Ames test (Salmonella typhimurium strain TA100) by hamster hepatic S9 preparation . This S9 activity is induced by administration of ethanol to the animals . The organic solvents dimethylsulphoxide (DMSO) and N-methyl-2-pyrrolidinone (MP) inhibit this mutagenicity, apparently because they inhibit DMN demethylase activity (assayed as formaldehyde production) . Ellagic acid, dissolved in DMSO or MP, had no inhibitory effect on DMN mutagenicity, beyond the effect of the solvent vehicle. Mutagenesis, 1989 Nov, 4(6), 446 - 52 Mutagenic nitrenes/nitrenium ions from azido-imidazoarenes and their structure-activity relationships; Wild D et al.; New heterocyclic arylazides (azido-imidazoarenes) structurally related to the food mutagen/carcinogen 2-amino-3-methyl-imidazo{4,5-f}quinoline (IQ) have been prepared . Their photolysis yields nitrenes and/or nitrenium ions which induce mutations in Salmonella typhimurium . The relationships between the chemical structure and mutagenic activity of these species are the same as those found in our previous studies of the amino- and nitro-imidazoarenes . Therefore the efficiency of the reaction with DNA of the ultimate metabolite, the nitrene/nitrenium ion, is the critical step governing the mutagenic potency of the amino- and nitro-imidazoarenes . The efficiency of DNA-binding depends on the delocalization of the positive charge of the nitrenium ion or of the electron deficiency of the nitrene . It is typical of the N-1-substituted and N-3-substituted arenimidazolyl-nitrenium ions that they can form another nitrenium resonance structure very similar to the parent nitrenium ion structure . We suggest that this property of the nitrene/nitrenium ion, in combination with its aromatic structure facilitating carbonium ion resonance structures, is the basic reason for the extremely potent mutagenic activity of IQ and related food mutagens/carcinogens. Food Chem Toxicol, 1989 Nov, 27(11), 723 - 30 The stability of the nitrosated products of indole, indole-3-acetonitrile, indole-3-carbinol and 4-chloroindole; Tiedink HG et al.; The nitrosation rates of indole-3-acetonitrile, indole-3-carbinol, indole and 4-chloroindole and the stability of their nitrosated products were investigated . Each of the nitrosated indole compounds was directly mutagenic to Salmonella typhimurium TA100 in the following order of potency: 4-chloroindole much greater than indole-3-carbinol greater than or equal to indole greater than indole-3-acetonitrile . Total N-nitroso determinations, carried out according to a modified method of Walters et al . (Analyst, Lond . 1978, 103, 1127), and Ames test results revealed that each of the indole compounds immediately formed mutagenic N-nitroso products upon nitrite treatment under acidic conditions . However, the nitrosation rates of indole and 4-chloroindole were higher than those of indole-3-acetonitrile and indole-3-carbinol . For indole-3-carbinol, indole-3-acetonitrile and indole, no change in the amount of nitrosated products was observed at increasing incubation times from about 15 up to 60 min . For 4-chloroindole the amount of nitrosated products decreased with increasing incubation times . In all cases the responses in the Ames test paralleled the amounts of nitrosated products . The stabilities of the nitrosated products of the indole compounds were investigated at pH 2 and 8 . Both mutagenicity data and measurements by high-performance liquid chromatography using a photohydrolysis detector indicated that the nitrosation products of indole-3-acetonitrile, indole-3-carbinol and indole were more stable at pH 8 than at pH 2 . Conversely, nitrosated 4-chloroindole was stable at pH 2 but not at pH 8 . The pH 8 chromatograms showed a large nitrite peak . From this we hypothesized that the presence of free nitrite might be responsible for the stability of nitrosated indole-3-acetonitrile, indole-3-carbinol and indole at pH 8 . Experiments confirmed the existence of an equilibrium between the nitrosated indole compound and the free indole compound plus nitrite. Poult Sci, 1989 Nov, 68(11), 1454 - 60 Age-related changes in the persistence and pathogenicity of Salmonella typhimurium in chicks; Gast RK et al.; Effects of age at exposure on the persistence of Salmonella in various tissues of chicks were assessed in two experiments . Broiler chicks, housed on wire floors in isolation cabinets, were orally inoculated with S . typhimurium at various ages (1 to 8 days after hatching) . The postinoculation mortality of chicks declined significantly (P less than .05) as the age at inoculation increased . One experiment investigated the effect of age at inoculation on the persistence of S . typhimurium in the cecum . Salmonella persisted for 7 wk after inoculation in 81.3% of the chicks inoculated at 1 day of age and in 62.5% of the chicks inoculated at 8 days of age . The mean number of cecal Salmonella at 7 wk postinoculation was also greater for chicks inoculated on Day 1 than for those inoculated on Day 8 . The second experiment examined the effect of age at inoculation on the adherence of S . typhimurium to and penetration through the cecal epithelium . The ceca of chicks inoculated at 1 day of age were colonized by significantly more adhering Salmonella at 2 days postinoculation (1.4 x 10(8)/g) than were those of chicks inoculated at 3, 5, or 7 days of age (8.0 x 16(6)/g or less), but age did not affect the recovery of S . typhimurium from livers or spleens. J Med Microbiol, 1989 Nov, 30(3), 213 - 7 The influence of cultural conditions on the expression in Salmonella typhimurium of an antigen related to cholera toxin; Qi GM et al.; The choice of strain, culture conditions, composition of medium and size of inoculum all affected the expression of a cholera-toxin-related antigen (CTRA) in Salmonella typhimurium . A previous study had shown that the number of organisms expressing CTRA in Casamino acid Yeast Extract (CYE) medium decreased between 4 h and 6 h in uninterrupted culture . In the present experiments, organisms harvested at 4-5 h were subcultured into fresh CYE medium and incubated for a further 2 h; the total number of organisms increased, and the decrease in the proportion of organisms expressing CTRA was reduced . Use of Hartley Digest Broth in place of CYE medium increased the proportion of organisms expressing CTRA in all strains tested, in both the uninterrupted and the subculture procedures . The higher the initial inoculum, the lower was the proportion of organisms expressing CTRA . The presence of the antigen in cells remained constant for about 18 h after transfer from 37 degrees C to 4 degrees C . These data have important implications for the production and purification of CTRA: they show that it was expressed during log-phase of growth, and they suggest that expression was regulated by a non-growth-limiting factor . Moreover, some avirulent strains were better producers of the antigen than virulent ones . The significance of the data is discussed in relation to the in-vivo situation. Mutat Res, 1989 Nov, 227(3), 135 - 45 Phenazine derivatives as the mutagenic reaction product from o- or m-phenylenediamine derivatives with hydrogen peroxide; Watanabe T et al.; 8 Kinds of o- and m-phenylenediamine (PD) derivatives, which are used as oxidative-type hair dyes, were treated with hydrogen peroxide (H2O2) . Both before and after H2O2 treatment, their mutagenicity was tested by using Salmonella typhimurium TA98 in the presence or absence of a mammalian metabolic activation system (S9 mix) . After H2O2 treatment, the mutagenic potencies of p-nitro-o-phenylenediamine, 3,4-diaminotoluene, p-nitro-m-phenylenediamine and 2,4-diaminophenol did not vary or slightly increased in comparison with those of the starting materials . The mutagenicity of o-PD, p-chloro-o-phenylenediamine (p-Cl-o-PD), m-PD and 2,4-diaminoanisole (p-OMe-m-PD) was enhanced remarkably by treatment with H2O2 and all the oxidation products required metabolic activation by S9 mix for their mutagenesis . In a gas chromatography/mass spectrometric study, 2,3-diaminophenazine and 2,7-diaminophenazine were identified with authentic samples in o-PD and m-PD oxidation mixture, respectively . The oxidation mixture obtained from p-Cl-o-PD and p-OMe-m-PD was separated into several fractions by repeated column chromatography . Brownish yellow crystals were isolated from oxidized p-Cl-o-PD and the structure of the compound was determined to be 2,3-diamino-7-chlorophenazine from physicochemical and chemical evidence . Two reddish yellow crystals, obtained from oxidized p-OMe-m-PD, were 2,7-diamino-3,8-dimethoxyphenazine and 2,7-diamino-3-methoxyphenazine . The number of revertants induced by 1 nmole of phenazines detected from oxidized PD derivatives was as follows; 2,3-diaminophenazine: 349 rev.; 2,3-diamino-7-chlorophenazine; 406 rev.: 2,7-diaminophenazine: 12 110 rev.; 2,7-diamino-3,8-dimethoxyphenazine: 4229 rev.; 2,7-diamino-3-methoxyphenazine: 24 640 rev . in S . typhimurium TA98 strain with 25 microliters S9 per plate. J Bacteriol, 1989 Nov, 171(11), 5776 - 82 Cloning of Salmonella typhimurium DNA encoding mutagenic DNA repair; Thomas SM et al.; Mutagenic DNA repair in Escherichia coli is encoded by the umuDC operon . Salmonella typhimurium DNA which has homology with E . coli umuC and is able to complement E . coli umuC122::Tn5 and umuC36 mutations has been cloned . Complementation of umuD44 mutants and hybridization with E . coli umuD also occurred, but these activities were much weaker than with umuC . Restriction enzyme mapping indicated that the composition of the cloned fragment is different from the E . coli umuDC operon . Therefore, a umu-like function of S . typhimurium has been found; the phenotype of this function is weaker than that of its E . coli counterpart, which is consistent with the weak mutagenic response of S . typhimurium to UV compared with the response in E . coli. Infect Immun, 1989 Nov, 57(11), 3276 - 80 A Salmonella typhimurium virulence gene linked to flg; Carsiotis M et al.; Isogenic pairs of strains of Salmonella typhimurium which differed only in whether or not they were flagellate were found to be equally virulent in C57BL/6J mice infected orally, intravenously, or intraperitoneally . Therefore, we investigated the genetic basis for our previous observation that in this mouse model, nonflagellate delta flagABCDE25 strains were reduced in virulence compared with isogenic wild-type flagellate strains . The recombinant plasmid pMH6, which contains several flg+ genes and a segment of the S . typhimurium chromosome adjacent to the flg genes, was introduced into a delta flgABCDE25 mutant . This restored virulence in mice challenged intraperitoneally, which suggested that a virulence gene occurs adjacent to the flg genes . When plasmid pMH64, which lacks the chromosomal segment adjacent to the flg genes, was introduced into the same delta flgABCDE25 mutant, virulence was not restored . In contrast, the introduction of pMH71, a plasmid which retains the chromosomal segment adjacent to the flg genes, restored virulence . We concluded that a hitherto unknown virulence gene, which we have named mviS, occurs adjacent to the flg genes and that its absence in delta flgABCDE25 mutants, rather than the nonflagellate phenotype of the delta flgABCDE25 mutants, caused the previously reported attenuation of such mutants. Carcinogenesis, 1989 Nov, 10(11), 2119 - 22 Genotoxicity and effects on rat liver drug-metabolizing enzymes by possible substitutes for 4,4'-methylene bis(2-chloroaniline); Wu K et al.; The mutagenic properties of Ethacure 300, Cyanacure and Polacure 740M, all possible substitutes for the industrial carcinogen, 4,4'-methylene bis(2-chloroaniline), have been determined in Salmonella typhimurium strains TA100, TA98, TA1535 and TA1537 . These data have been compared with the effects of these chemicals on ethoxyresorufin O-deethylase (EROD) activity and aldrin epoxidase (AE) activity in rat liver . Ethacure 300 was clearly positive in both TA100 and TA98 bacterial strains, while Cyanacure was positive only in TA100 . Polacure 740M was negative in all strains . Ethacure 300 caused a 28-fold induction of EROD while Cyanacure caused a doubling . Polacure 740M was without effect . Neither Ethacure 300 nor Cyanacure affected AE, while Polacure 740M caused an increase at only the lower dose tested . Thus there was excellent correlation between mutagenicity and EROD induction . A similar correlation was noted for six other structurally related compounds giving support to the contention that the ability of a chemical to induce EROD bears some relationship to its carcinogenic potential. Carcinogenesis, 1989 Nov, 10(11), 2019 - 24 Singlet oxygen as an ultimately reactive species in Salmonella typhimurium DNA damage induced by methylene blue/visible light; Epe B et al.; The specific recognition of various DNA modifications by repair enzymes is exploited for the analysis of DNA damage induced by visible light in the presence of methylene blue in Salmonella typhimurium . The relative frequencies of various endonuclease-sensitive sites and strand breaks are determined in the plasmid pAQ1 of the treated bacteria and are compared with those observed after exposure of isolated DNA to various conditions . This comparison of damage profiles indicates that the cellular DNA damage by illumination in the presence of methylene blue is caused predominantly by the direct action of singlet oxygen . Indirect mechanisms, e.g . involving a generation of superoxide and hydroxyl radicals or the activation of cellular nucleases, do not contribute very much . The damage is dominated by base modifications . These are subject to an efficient repair that is not mediated by uvrABC proteins and therefore most probably involves recognition by specific glycosylases . Revertant frequencies observed under these conditions in the strains TA1535, TA100, TA2638 and TA104 indicate a pronounced mutagenicity of the lesions induced . On the other hand, the DNA damage does not contribute significantly to the cytotoxicity caused by the treatment as an excision repair deficiency (uvrB) has no influence on cell killing. Arch Exp Veterinarmed, 1989 Nov, 43(6), 849 - 54 {The secondary microbial colonization of organ samples for bacterial meat examination}; Schuppel H et al.; The capability of bacteria to penetrate liver, spleen, and kidney samples was investigated, using one strain each of Salmonella typhimurium . Serratia marcescens, and Micrococcus luteus . The intact organ capsule was found to be an effective barrier to bacterial invasion, even at room temperature and with high contamination doses . Injuries to or absence of the organ capsule led to massive secondary germ colonisation of samples within 5 hours, even under conditions of cool storage . Germ colonisation of the sample interior will inevitably start from cut surfaces and cannot be prevented, if samples have to be stored several hours or transported, since sterile sampling is not possible under slaughterhouse conditions . Hence, new approaches have to be found to bacteriological carcass inspection. Immunopharmacology, 1989 Nov-Dec, 18(3), 157 - 66 Suppression of avidin processing and presentation by mouse macrophages after sublethal exposure to dieldrin; Krzystyniak K et al.; The molecular events in macrophage antigen processing and presentation were examined to determine the possible site(s) of cell-xenobiotic interaction . Antigenic processing by mouse peritoneal macrophages of a single protein antigen, avidin, was significantly suppressed following sublethal exposure of animals to an organochlorine pesticide, dieldrin . Exposure of C57B1/6 female mice to dieldrin affected the in vitro uptake of {methyl-14C}avidin by peritoneal macrophages and markedly decreased phagocytosis of fluorescein-labelled microspheres and Salmonella typhimurium . Release of the processed avidin, determined by immunochemical quantification of immunogenic avidin and by bioassay of immunogenicity of the released antigen, was also markedly affected . Dieldrin markedly affected presentation of avidin on the macrophage surface, observed by cytoimmunochemical staining of the antigen with fluorescent antibody and flow cytometry . Inhibition of the release of processed avidin was dieldrin dose- and time-dependent, following single sublethal intraperitoneal (ip) exposure to the pesticide . The antigenic properties of processed avidin, determined by biological assay using lymphocyte cultures of normal C57B1/6 mice primed with avidin, were proportional to the antigen concentration in supernatants of macrophage cultures, for both vehicle controls and dieldrin-exposed animals . This observation and analysis of the kinetics of release of processed avidin by macrophages from control and dieldrin-exposed animals suggested that the release of processed avidin, but not the immunogenicity of the antigen itself, was affected by the pesticide exposure . Generally, impairment of avidin processing and presentation appeared to be more dramatic than other pesticide-related injuries to macrophages, such as the uptake of the antigen . In conclusion, antigen processing could be a sensitive target for dieldrin-related injury of macrophage functional activities, which, in consequence, could produce suppression of the humoral immune response. Plasmid, 1989 Nov, 22(3), 256 - 9 Tn4527, a Tp Sp/Sm transposon related to Tn7 and flanked by IS1; Dumans AT et al.; Tn4527 was isolated from a Salmonella typhimurium strain obtained in Brazil . Its size is 19.6 kb and it carries resistance to trimethoprim, spectinomycin, and streptomycin, as in the case of Tn7 (14 kb) . A restriction analysis of the transposon shows regions of similarity to Tn7 mixed with extra DNA . The 2.6-kb and 2.2-kb HindIII fragments of Tn7, which encode transposition-related proteins, show homology to Tn4527 . In contrast to Tn7, Tn4527 is flanked by direct repeats, which seem to be IS1's, as they have appropriate restriction sites and hybridize both to IS1 and to internal IS1 oligonucleotides. Microb Pathog, 1989 Nov, 7(5), 337 - 46 Effect of Salmonella typhimurium porins on biological activities of human polymorphonuclear leukocytes; Tufano MA et al.; The effect of Salmonella typhimurium porins on human polymorphonuclear leukocytes (PMNs) was studied . Labeled porins were shown to bind to the PMNs, and could be completely displaced by unlabeled porins . The binding caused modifications of membrane integrity and of the physico-chemical characteristics of the PMN surface, e.g . decreased oxidative burst, decreased hydrophobicity and altered cell morphology . The porins acted as both chemotaxins and chemotaxinogens . When PMNs were preincubated with porins their migration in the presence of commonly used chemoattractants (serum activated by zymosan or N-formyl-L-methionyl-L-leucyl-L-phenylalanine) was inhibited. J Bacteriol, 1989 Nov, 171(11), 6330 - 7 Mutational analysis of the histidine operon promoter of Salmonella typhimurium; Shand RF et al.; We isolated a collection of 67 independent, spontaneous Salmonella typhimurium his operon promoter mutants with decreased his expression . The mutants were isolated by selecting for resistance to the toxic lactose analog o-nitrophenyl-beta-D-thiogalactoside in a his-lac fusion strain . The collection included base pair substitutions . small insertions, a deletion, and one large insertion identified as IS30 (IS121), which is resident on the Mu d1 cts(Apr lac) phage used to construct the his-lac fusion . Of the 37 mutations that were sequenced, 14 were unique . Six of the 14 were isolated more than once, with the IS30 insertion occurring 16 times . The mutations were located throughout the his promoter region, with two in the conserved - 35 hexamer sequence, four in the conserved - 10 hexamer sequence (Pribnow box), seven in the spacer between the - 10 and -35 hexamer sequences, and the IS30 insertions just upstream of the -35 hexamer sequence . Four of the five substitution mutations changed a consensus base pair recognized by E sigma 70 RNA polymerase in the -10 or -35 hexamer . Decreased his expression caused by the 14 different his promoter mutations was measured in vivo . Relative to the wild-type promoter, the mutations resulted in as little as a 4-fold decrease to as much as a 357-fold decrease in his expression, with the largest decreases resulting from changes in the most highly conserved features of E sigma 70 promoters. J Bacteriol, 1989 Nov, 171(11), 5860 - 5 Fine-structure genetic map of the maltose transport operon of Salmonella typhimurium; Schneider E et al.; We have constructed a fine-structure genetic map of the maltose transport operon in Salmonella typhimurium . We have isolated mal mutants by using indicator plates, penicillin selection, or a proton suicide technique . Mutants were obtained as spontaneous events or were induced by chemical mutagenesis and transposon insertion . Tn10 and Mu d(lac Ap)1 insertion mutations were used to create deletions . Mutations were also obtained in a gene that is equivalent to lamB in Escherichia coli, which codes for the lambda bacteriophage receptor . The gene products in the mutants were characterized by sodium dodecyl sulfate-polyacrylamide-gel electrophoresis and immunoblotting . Our data indicate that the location of this operon on the Salmonella chromosome as well as the gene order and its orientation are the same as those in E . coli . This map will be useful in studying the mechanism of periplasmic transport in S . typhimurium. Mutagenesis, 1989 Nov, 4(6), 437 - 8 Genotoxic potential of crown ethers in Salmonella typhimurium; Arenaz P et al.; Macrocyclic polyethers (crown ethers) are a family of compounds which possess the ability to transport ionic species across natural and artificial membranes . Because of this characteristic, they have wide applications in industry and are being investigated for their potential as pharmacologic agents . However, these compounds are highly cytotoxic in both prokaryotes and eukaryotes . Because of the cytotoxicity of crown ethers, an investigation of the potential genotoxicity of these compounds in Salmonella typhimurium was initiated . Several unsubstituted and substituted crown ethers did not induce a genotoxic response in S . typhimurium strains TA100, TA1530, TA98 and TA1537 either with or without rat liver S9 mixture . The data support the conclusion that the toxicity of these compounds is probably not due to an interaction with nucleic acid to induce premutagenic lesions and they do not appear to be genotoxic in prokaryotes. Food Chem Toxicol, 1989 Nov, 27(11), 715 - 21 Non-clastogenicity in mouse bone marrow of fructose/lysine and other sugar/amino acid browning products with in vitro genotoxicity; MacGregor JT et al.; Heated sugar/amino acid reaction mixtures, known to contain products that are clastogenic and/or mutagenic to cells in vitro, were evaluated for clastogenic activity in mouse bone marrow using the erythrocyte micronucleus assay . Heated (i.e . browned) fructose/lysine reaction mixtures were also evaluated in the Salmonella his-reversion assay and the Chinese hamster ovary (CHO) cell chromosomal aberration assay to confirm and extend previous in vitro observations . Significant mutagenicity of fructose/lysine mixtures was observed in Salmonella typhimurium strains TA100, TA2637, TA98 and TA102, with greater activity in mixtures heated at pH 10 than at pH 7 . S-9 decreased the activity in strains TA100, TA2637 and TA98, but increased the activity in strain TA102 . Both pH 7 and pH 10 reaction mixtures of the fructose/lysine browning reaction were highly clastogenic in CHO cells . Heated mixtures of fructose and lysine, and of glucose or ribose with lysine, histidine, tryptophan or cysteine, did not increase the frequency of micronucleated erythrocytes in mice when administered by the oral route . This indicates the absence of chromosomal aberrations in erythrocyte precursor cells, and indicates that the genotoxic components of the browned mixtures are not absorbed and distributed to bone marrow cells in amounts sufficient to induce micronuclei when given orally . Because sugar/amino acid browning reactions occur commonly in heated foods, it is important to evaluate further the in vivo genotoxicity of browning products in cell populations other than bone marrow. Zentralbl Veterinarmed A, 1989 Nov, 36(9), 664 - 75 Clinical, endocrinological and spermatological studies after endotoxin injection in the boar; Wallgren M; Three adult boars were injected intravenously with endotoxin from Salmonella typhimurium . Blood plasma was analysed for the contents of 15-ketodihydro-PGF2 alpha, LH and testosterone . Total amount of white blood cells and differential counts were determined in whole blood . Semen was examined for concentration, motility, volume and morphological appearance of the spermatozoa . The boars were slaughtered three months after the endotoxin injection and the testes were examined . The total number of white blood cells decreased and the levels of 15-ketodihydro-PGF2 alpha rose immediately after the endotoxin administration . An initial increase in LH was seen in two out of the three boars . The increase in LH was followed by a testosterone increase in one boar and a testosterone decrease in the other . The third boar showed no initial increase in LH but an increase in testosterone . Semen examination demonstrated various morphological changes of the spermatozoa in all boars . The changes started to appear at about the same time after the endotoxin injection, but differed among the individuals . The examination of the testes depicted no changes from what is seen in normal animals . The present results indicate that the boar responds to endotoxin similar to what is seen in the ram . The endocrine changes, e.g . in LH and testosterone, are similar to those seen after termination of heat stress . The seminal changes indicate a disturbance located in the epididymis as well as a short-term, mild degeneration in the seminiferous epithelium. Jpn J Cancer Res, 1989 Nov, 80(11), 1021 - 3 Mutagenicity arising from boiled rice on treatment with nitrous acid; Hayatsu H et al.; When an aqueous homogenate of boiled rice was treated with nitrous acid at pH 3, direct-acting mutagens were formed . The presence of the mutagens was demonstrated by isolating the mutagenic fractions through blue-rayon adsorption, a method used to extract polycyclic compounds, and subsequent high-performance liquid chromatography (HPLC) . The mutagens were active in Salmonella typhimurium TA100 and TA98 without metabolic activation . Several different mutagens were formed, as judged from the HPLC profile. Biochem Pharmacol, 1989 Nov 1, 38(21), 3811 - 7 Metabolism of fusarin C by rat liver microsomes . Role of esterase and cytochrome P-450 enzymes with respect to the mutagenicity of fusarin C in Salmonella typhimurium; Lu SJ et al.; Fusarin C (FC) is a potent mutagen present on Fusarium moniliforme contaminated corn . This compound requires metabolic activation for which microsomes from phenobarbital-induced rats are most effective . Inhibition of the simultaneously induced esterase activity, which produced a less mutagenic metabolite, doubled the mutagenicity of FC . Carbon monoxide inhibited the mutagenicity of FC, suggesting the involvement of a heme containing enzyme . However, monoclonal antibodies specific for the phenobarbital-induced cytochrome P-450 enzymes PB-4 and PB-5, while inhibiting O-demethylation of p-nitroanisole and aflatoxin B1 mutagenicity, had not effect on FC mutagenicity . This implies that either these enzymes are not involved in the activation of FC or FC competes well with the antibodies for binding to the cytochrome P-450 enzymes . Two additional metabolites of FC were detected . One had an ultraviolet spectrum similar to FC: the other had a lambda max at 326 nm, and its retention time on reverse phase HPLC was very sensitive to changes in pH. J Photochem Photobiol B, 1989 Nov, 4(2), 171 - 84 Partition of rose bengal anion from aqueous medium into a lipophilic environment in the cell envelope of Salmonella typhimurium: implications for cell-type targeting in photodynamic therapy; Dahl TA et al.; Photodynamic therapy employs photosensitizers for the selective destruction of tumor tissue while sparing the surrounding healthy tissue . Photosensitization may also be applied to the selective eradication of microorganisms . Photosensitized inactivation requires that the sensitizer bind to the target and therefore the factors that determine photosensitizer binding are critical to photosensitization selectivity . This paper reports the determination of some features of the binding site of the potent photosensitizer, Rose Bengal, in Salmonella bacteria and describes some of the factors that affect this binding . The shift in the wavelength of maximum fluorescence and experiments with the fluorescence quencher TNBS indicate that Rose Bengal is located in a non-aqueous compartment such as the outer membrane . The dye does not seem to significantly accumulate inside the cell, but rather to accumulate in the outer membrane . Time-dependent changes in sensitizer localization in two strains of Salmonella typhimurium that differ in cell wall formation, LT-2 and TA1975, correspond to their differences in susceptibility to photosensitized killing . Therefore these results provide clues to the factors that determine photosensitization selectivity . Understanding this phenomenon is essential for the efficient design of selective photosensitizers and for optimizing antitumor and antiviral photodynamic therapy. Ann Ig, 1989 Nov-Dec, 1(6), 1445 - 58 {Antimicrobial activity exerted by sodium dichloroisocyanurate}; D'Auria FD et al.; Sodium dichloroisocyanurate is a chlorinated cleaner . It was used for swimming pool sanitation and for the sterilisation of linen . Not recently ago sodium dichloroisocyanurate has substituted hypochlorite for the sterilisation of infant feeding bottles and teats . Sodium dichloroisocyanurate is soluble in water; this condition causes the hydrolysis of sodium dichloroisocyanurate in hypochlorous acid, that is the active agent, isocyanurate and isocyanurate chlorine . These compounds form a chlorine protein that carry out microbicidal activity . In a toxicology study has been shown that no severe changes in the normal metabolic function occurred, furthermore sodium dichloroisocyanurate has not shown teratogenic effects at the concentration of 200 mg/kg . The antimicrobial activity of sodium dichloroisocyanurate was evaluated against Gram negative bacteria such as E . coli or Salmonella typhimurium and against some fungi . This study illustrates a rapid antimicrobial activity using concentrations . Our study concentrated on the antimicrobial activity of sodium dichloroisocyanurate in some experimental conditions . We tested 66 strains of fungi, 28 Gram positive bacteria and 29 Gram negative bacteria . We also evaluated the antimicrobial activity of sodium dichloroisocyanurate against protozoa such as Trichomonas vaginalis . The antimicrobial activity was evaluated in cultural conditions and non cultural conditions; in these experiments we observed similar action in both the commercial product and pure substance . In cultural conditions sodium dichloroisocyanurate shows a good activity against fungi and bacteria, moreover it can be observed that the serum didn't interfere with its activity . In a non cultural condition the Candida was killed rapidly by the sodium dichloroisocyanurate but this activity is influenced by the growth phase of the yeast . Against mycelial form such as Penicillium and Aspergillus the sodium dichloroisocyanurate needs a longer contact time than yeast form for its activity . It is interesting to note that well known bacteria, that are resistant to the common antimicrobial agents, such as Pseudomonas aeruginosa, were inhibited by sodium dichloroisocyanurate in a rapid bactericidal action . Our data demonstrates that no significant adverse influence on the activity of sodium dichloroisocyanurate was shown by pH and by temperature even if in some experimental conditions increased activity was noticed at pH = 6.6 . The sodium dichloroisocyanurate has demonstrated good activity against Trichomonas vaginalis . This fact extends the broad-spectrum activity of sodium dichloroisocyanurate to the protozoa . In conclusion, sodium dichloroisocyanurate has demonstrated a good activity against all tested strains, furthermore its activity did not decrease in the presence of 1% of organic substance (serum etc.).(ABSTRACT TRUNCATED AT 400 WORDS) J Biol Chem, 1989 Oct 25, 264(30), 17681 - 90 Refined atomic model of glutamine synthetase at 3.5 A resolution; Yamashita MM et al.; An atomic model of 43,692 non-hydrogen atoms has been determined for the 12-subunit enzyme glutamine synthetase from Salmonella typhimurium, by methods of x-ray diffraction including restrained least-squares atomic refinement against 65,223 unique reflections . At 3.5 A resolution the crystallographic R-factor (on 2 sigma data) is 25.8% . As reported earlier for the unrefined structure, the 12 subunits are arranged in two layers of six; at the interface of pairs of subunits within each layer, cylindrical active sites are formed by six anti-parallel beta strands contributed by one subunit and two strands by the neighboring subunit . This interpretation of the electron density map has now been supported by comparison with glutamine synthetase from Escherichia coli by the Fourier difference method . Each active site cylinder holds two Mn2+ ions, with each ion having as ligands three protein side chains and two water molecules (one water shared by both metals), as well as a histidyl side chain just beyond liganding distance . The protein ligands to Mn2+ 469 are Glu-131, Glu-212, and Glu-220; those to Mn2+ 470 are Glu-129, His-269, and Glu-357 . The two layers of subunits are held together largely by the apolar COOH terminus, a helical thong, which inserts into a hydrophobic pocket formed by two neighboring subunits on the opposite ring . Also between layers, there is a hydrogen-bonded beta sheet interaction, as there is between subunits within a ring, but hydrophobic interactions account for most of the intersubunit stability . The central loop, which extends into the central aqueous channel, is subject to attack by at least five enzymes and is discussed as an enzyme "passive site." FEBS Lett, 1989 Oct 9, 256(1-2), 155 - 8 Lipopolysaccharide toxin can directly stimulate the intracellular accumulation of lipids and their secretion into medium in the primary culture of rabbit hepatocytes; Victorov AV et al.; Low doses (0.1-0.3 micrograms/ml per 10(6) cells) of the lipopolysaccharide toxin (LPS) from Salmonella typhimurium were shown to increase (after an 18 h incubation) the intracellular content of free cholesterol (CH), esterified cholesterol (EC) and triglycerides (TG) by 30-40% in the primary culture of rabbit hepatocytes . A similar increase was found for the incorporation of {14C}acetate into these lipids . The concentration of lipids in cultural medium, under these conditions, was also augmented: by 30-40% for CH; by 50-60% for TG and by 60-80% for EC . Higher doses (up to 50 micrograms/ml) of LPS hardly affected the lipid content in hepatocytes but strongly (by two-fold) inhibited the secretion of lipids . It is suggested that in vivo low concentrations of LPS in bloodstream (in the absence of conspicuous pathology) might induce hyperlipidemia directly influencing on hepatic cells, while, under the higher concentrations of LPS, hyperlipidemia caused by cachectin (or tumor necrosis factor) is probably observed. Biochemistry, 1989 Oct 3, 28(20), 8174 - 80 Salmonella typhimurium histidinol dehydrogenase: complete reaction stereochemistry and active site mapping; Grubmeyer CT et al.; The stereochemistry of the L-histidinol dehydrogenase reaction was determined to be R at NAD for both steps, confirming previous results with a fungal extract {Davies, D., Teixeira, A., & Kenworthy, P . (1972) Biochem . J . 127, 335-343} . NMR analysis of monodeuteriohistidinols produced by histidinol/NADH exchange reactions arising via reversal of the alcohol oxidation reaction indicated a single stereochemistry at histidinol for that step . Comparison of vicinal coupling values of the exchange products with those of L-alaninol and a series of (S)-2-amino-1-alcohols allowed identification of the absolute stereochemistry of monodeuteriohistidinols and showed that histidinol dehydrogenase removes first the pro-S then the pro-R hydrogens of substrate histidinol . The enzyme stereochemistry was confirmed by isotope effects for monodeuteriohistidinols as substrates for the pro-R-specific dehydrogenation catalyzed by liver alcohol dehydrogenase . Active site mapping was undertaken to investigate substrate-protein interactions elsewhere in the histidinol binding site . Critical binding regions are the side-chain amino group and the imidazole ring, whose methylation at the 1- or 2-position caused severe decreases in binding affinity . Use of alternative substrates further clarified active site interactions with the substrate . Compounds in which the alpha-amino group was replaced by chloro, bromo, or hydrogen substituents were not substrates of the overall reaction at 1/10,000 the normal rate.(ABSTRACT TRUNCATED AT 250 WORDS) Genetika, 1989 Oct, 25(10), 1740 - 6 {A comparative analysis of mutagenic and SOS-induced activity in three classes of chemical compounds}; Vasil'eva SV et al.; Mutagenic and SOS-inducing potential of 23 derivatives of fluorenone, phenanthrenequinone and biphenyl have been studied in tester strains of Salmonella typhimurium and in Escherichia coli strain PQ 37 . 14 of these compounds revert the mutation hisD3052 (much less than -1 much greater than type), but none of them induce mutations in the strain TA 1535 . Maximal mutagenic activity has been shown in strain TA 1538 for amide of 2,7-dinitrofluorenone-4-carbonic acid (580 revertants per nmol), 2,7-dinitrophenanthrenequinone (308 revertants per nmol), 2,4,7-trinitrophenanthrenequinone (306 revertants per nmol) and 2',4,4'-trinitrobiphenyl-2-carbonic acid (251 revertants per nmol) . In plasmid-containing strain TA 98 the mutagenic potential of the compounds tested is lower than in the TA 1538 strain . It has been suggested that mutagenic activity of these compounds can be attributed to their acceptor properties, namely, the ability to form charge transfer complexes with DNA . SOS-inducing activity has been shown for 5 compounds, also positive in mutation induction . Mutagenic and SOS-inducing activities positively correlate in fluorenone derivatives . Among phenanthrenequinone derivatives, compounds with high mutagenic activity only can induce SOS response . None of the biphenyls tested induce SOS functions . The compounds giving the positive result in the SOS-chromotest have rigid co-planar structure. Klin Med (Mosk), 1989 Oct, 67(10), 108 - 11 {Immunologic status of patients with Salmonella infections}; Frolov VM et al.; Salmonella typhimurium infection was diagnosed in 186 patients aged 18-56 . The clinical picture was that of gastroenteritis (73.1%), enteritis (14.0%), gastritis (6.45%), gastroenterocolitis (6.45%) . Salmonellosis of moderate severity presented in 88.7% of patients, a severe course occurred in 11.3% . Concomitant disorders arose in 22.6% of cases . Immunological investigation disclosed T-lymphopenia, reduced number of multireceptor RFC, both T-helpers and T-suppressors . The levels of 0-lymphocytes and CIC were on the increase . Salmonellosis of long duration was characterized by hyperactivity of autoimmune reactions. Chem Pharm Bull (Tokyo), 1989 Oct, 37(10), 2838 - 40 A mutagenic new iridoid in the water extract of catalpae fructus; Nozaka T et al.; A mutagenic principle in the water extract from Catalpae Fructus (originated from Catalpa ovata G . DON) (Bignoniaceae) was isolated and characterized as a new iridoid named catalpin . The iridoid exhibited mutagenic activity towards Salmonella typhimurium strain TA100 in the presence and absence of rat liver homogenate (S9) mix in Ames' test. Can J Vet Res, 1989 Oct, 53(4), 378 - 84 Hybridization studies with a DNA probe derived from the virulence region of the 60 Mdal plasmid of Salmonella typhimurium; Poppe C et al.; Plasmid DNA of 68 strains of Salmonella that belonged to 18 serovars and exhibited 48 different plasmid profiles was examined for hybridization with a 32P-labelled DNA probe which consisted of a 3750 base pairs (bp) HindIII-HindIII fragment derived from the virulence region of the 60 megadalton (Mdal) plasmid of Salmonella typhimurium . The 32 Mdal plasmid of S . cholerae-suis, the 50 Mdal plasmid of S . dublin, the 36 Mdal plasmid of S . enteritidis, the 60 Mdal plasmid of S . gallinarum, the 60 Mdal plasmid of S . pullorum, and the 60 Mdal plasmid of S . typhimurium, plasmids that have been associated with virulence, all hybridized with the probe . Digestion of plasmid DNA of these strains with PvuII and hybridization with the probe revealed that the plasmids of strains of all six serovars contained fragments of approximately 2520 and 1520 bp that hybridized with the probe . Similarly, hybridization with BglI digests of DNA of the virulence-associated plasmids of strains of these six serovars showed that all six plasmids contained a fragment of approximately 3690 bp that hybridized with the probe . No other plasmids of these strains nor any plasmids of 12 other Salmonella serovars hybridized with the probe . Chromosomal DNA did not hybridize with the probe . The 60 Mdal plasmids of S . gallinarum and S . pullorum showed similar digestion patterns with restriction endonucleases BglI, BglII and PvuII. Poult Sci, 1989 Oct, 68(10), 1357 - 60 Prevention of Salmonella typhimurium colonization of broilers with D-mannose; Oyofo BA et al.; Broiler chickens can be contaminated by Salmonella typhimurium, which is a food safety concern . It has been previously shown that D-mannose blocks S . typhimurium adherence to chicken intestine in vitro . One-day-old broiler chickens were fed normal drinking water or drinking water supplemented with 2.5% mannose for 10 days . On Day 3, both groups were challenged orally with 1 x 10(8) S . typhimurium {ST-10 (Animal Diagnostics Laboratory, Ames, IA)} resistant to Nal and Nov (Sigma, St . Louis, MO) . On Day 10 the birds' caecal contents were examined for the antibiotic-marked S . typhimurium . Two additional groups of birds were provided normal drinking water or mannose but were not challenged with the bacteria . Salmonella-challenged control chickens were 78, 82, and 93% colonized whereas Salmonella-challenged mannose-treated chickens were only 28, 21, and 43% colonized . Moreover, the mean log10 counts of control and mannose groups were significantly (P less than .001) reduced by at least 99% . Mannose-supplemented drinking water had no effect on weight gains . Certain carbohydrates may provide a means to reduce S . typhimurium contamination in broilers. Poult Sci, 1989 Oct, 68(10), 1351 - 6 Inhibition by mannose of in vitro colonization of chicken small intestine by Salmonella typhimurium; Oyofo BA et al.; The in vitro adherence of {3H}thymidine-labeled Salmonella typhimurium isolates to the small intestine of one-day-old chickens was investigated . Bacteria were screened for mannose sensitivity and mannose-resistance binding properties . Type 1 fimbriae positive strains adhered significantly better than Type 2 fimbriae-negative strains . Adherence was significantly (P less than .05) inhibited by D-mannose, methyl-alpha-D-mannoside, arabinose, and galactose . Adherence was both time and temperature dependent . These findings suggest that the small intestine of the chicken has receptors for bacteria with Type 1 fimbriae . The function of the receptors is dependent on a mannose moiety . Bacteria adhered better to fresh intestine cells than to cells held overnight at 4 C . Thus, adherence was dependent upon a metabolically active host cell . The in vitro adherence assay may further be used to study the interaction of bacteria with chicken enterocytes. Zentralbl Bakteriol, 1989 Oct, 271(4), 493 - 500 Enhancement of protection against Salmonella infection in mice mediated by a synthetic lipopeptide analogue of bacterial lipoprotein in S . typhimurium vaccines; Schlecht S et al.; Vaccines consisting of acetone-killed Salmonella typhimurium were supplemented with a synthetically prepared lipopeptide derivative of bacterial lipoprotein, Pam3Cys-Ser-Ser-Asn-Ala . NMRI mice were immunized with these vaccines, receiving two intraperitoneal injections and were challenged intraperitoneally with graded doses of S . typhimurium C5 . The protective capacity of the supplemented vaccines was compared with that of the unsupplemented bacterial vaccine, and with the effectiveness of the supplementing component alone . The LD50 served as a criterion for protective capacity . The results showed that 90% of the S . typhimurium S-form vaccine could be replaced by the adjuvant lipopeptide without a recognizable decrease in protective immunizing capacity . A similar but less pronounced enhancement of protection was obtained with a R-mutant vaccine supplemented with the lipopeptide; by supplementing the standard vaccine dose with lipopeptide an increase in protection was also achieved . Lipopeptide alone was not effective in protecting mice from infection with S . typhimurium. Toxicol Lett, 1989 Oct, 49(1), 1 - 13 Protein A protects mice from depletion of biotransformation enzymes and mortality induced by Salmonella typhimurium endotoxin; Dwivedi PD et al.; Changes in hepatic microsomal mixed-function oxidase enzyme levels (aniline hydroxylase, aminopyrine demethylase, glutathione S-transferase), glutathione content, total sulphydryl content, and plasma enzyme levels of aspartate transaminase, alanine transaminase and alkaline phosphatase were studied in male Swiss albino mice exposed to Salmonella typhimurium endotoxin (50-150 micrograms per mouse, LC50 141.82 micrograms) . Animals exposed to the same dose of endotoxin but pretreated with protein A of Staphylococcus aureus (5 micrograms/per mouse) protected the animals from both mortality and depletion of biotransformation enzymes. Epidemiol Infect, 1989 Oct, 103(2), 235 - 41 Persistence of S . typhimurium in a large dairy herd; Giles N et al.; Salmonella typhimurium 49a infection in a large dairy herd persisted for 3.5 years . Illness initially occurred in cows and calves but latterly although there were fewer clinical cases milk filters were culturally positive on 26 out of 73 samplings . Three associated human disease incidents occurred . Individual milk samples identified one cow as an excreter and the organism was recovered from the mammary gland of this animal at slaughter . Correlation between calving pattern, the times of calving and the occurrence of positive milk filters suggest that the cow may have been excreting the organism intermittently from the udder for 2.5 years. Epidemiol Infect, 1989 Oct, 103(2), 219 - 25 A national outbreak of Salmonella typhimurium DT 124 caused by contaminated salami sticks; Cowden JM et al.; An outbreak of Salmonella typhimurium DT 124 infection which affected 101 people in England in December 1987 and January 1988 was detected through surveillance of laboratory reports from medical microbiology laboratories of the NHS and PHLS . Within 1 week of noting the increase in reports, epidemiological and microbiological investigations identified a small German salami stick as the vehicle of infection and the product was withdrawn from sale . The epidemiological investigation highlighted the occurrence of a long incubation period, bloody diarrhoea . Prompt recognition and investigation of the outbreak prevented further cases of severe infection. Anticancer Drug Des, 1989 Oct, 4(3), 209 - 19 Bacterial mutagenicity studies of DNA-intercalating aniline mustards: an insight into the mode of action of a novel class of anti-tumour drugs; Ferguson LR et al.; Bifunctional alkylating agents are reactive compounds which work by crosslinking DNA, but which have no special affinity for it . A series of acridine-linked aniline mustards of widely-varying alkylator reactivity (5-11), designed as DNA-directed alkylating agents, have been evaluated in various strains of Salmonella typhimurium with differing DNA repair capabilities to obtain information about their mechanism of action . The compounds showed greatly increased potency (determined as D37 values) compared with the corresponding untargeted mustards, in the repair-proficient strain TA1978+ . All but the most unreactive mustards were considerably more potent (greater than 10-fold) in the corresponding repair-deficient strain TA98, indicating that DNA-crosslinking is the major cytotoxic mechanism . However, the mutagenic profile of the compounds in four Salmonella strains, particularly in the excision repair-deficient strains TA98 and TA100, suggest the compounds also form substantial levels of mutagenic monoadducts . The possibility that intercalative binding by the acridine chromophore provides an additional geometrical restraint on cross-linking by the mustard is an important facet of design which needs further study. Proc Soc Exp Biol Med, 1989 Oct, 192(1), 81 - 6 Concanavalin A promotes adherence of Salmonella typhimurium to small intestinal mucosa of rats; Abud RL et al.; A number of dietary lectins have been shown to resist proteolytic digestion . These lectins interact with the small intestinal mucosa causing structural and functional changes . Concomitant to these changes, bacterial overgrowth was reported and a possible interaction between lectins and bacteria in the small intestine was postulated . The aim of this study was to investigate the effect of various lectins on adherence of Salmonella typhimurium to both isolated small intestinal enterocytes and ligated intestinal loops . Isolated intestinal cells or ligated intestinal loops were incubated with {3H} adenine-S . typhimurium in the presence or absence of concanavalin A, phytohemagglutinin, peanut agglutinin, and wheat germ agglutinin . Only concanavalin A promoted the adherence of various strains of nonfimbriated S . typhimurium to isolated viable intestinal cells . Other lectins showed no effect on the adherence . In situ studies showed that bacterial binding was increased in concanavalin A-treated intestinal loops, supporting the significance of the experiments in vitro . These data suggest that lectins may act by promoting bacterial adherence to the small intestine, thereby facilitating colonization and infection, and leading to bacterial overgrowth. Mutat Res, 1989 Oct, 224(2), 219 - 27 The mutagenic activity of sodium perborate; Seiler JP; Sodium perborate (CAS No . 1333-73-9, 10486-00-7, or 13517-20-9, depending on the structural formula given) is produced in huge amounts mainly for its use as a bleaching agent in laundry detergents . Its action involves the liberation of active oxygen species at elevated temperatures . In view of the widespread use of this compound it is surprising to note that no mutagenicity test data yet exist . The investigations reported in this paper have shown that sodium perborate is indeed capable of producing mutagenic changes in a number of in vitro test systems . Its potential for inflicting damage to DNA could be demonstrated in an assay which is tailored to probe for oxidative damage induced by a chemical agent . As expected, sodium perborate proved to be able to oxidize thymidine to an appreciable extent at an incubation temperature of 80 degrees C, but even at 40 degrees C thymidine oxidation was measurable . The compound induced point mutations in the Salmonella typhimurium strains TA100 and TA102, while TA98 did not respond . Also, incubation in the presence of a mammalian auxiliary metabolic system (rat liver S9) abolished the mutagenic activity completely . Finally, Chinese hamster ovary cells (strain CHO-K1) were shown to undergo extensive chromosomal damage when treated with sodium perborate . The rather unusual prevalence of chromosome rearrangements was especially noted . Sodium perborate is thus to be regarded as a direct-acting in vitro mutagen. J Med Microbiol, 1989 Oct, 30(2), 149 - 56 Quantification of the leucocyte influx into rabbit ileal loops induced by strains of Salmonella typhimurium of different virulence; Wallis TS et al.; Leucocyte influx into rabbit ileal loops, induced by strains of Salmonella typhimurium of different virulence, was assessed with 111Indium-labelled leucocytes . Strains fell into two groups on the basis of their leucotactic potential: "virulent" strains (which induced fluid secretion) caused a dose-dependent leucocyte influx; strains which did not induce fluid secretion failed to induce a significant leucocyte influx . Fluid secretion was never observed in the absence of leucocyte influx, but leucocyte influx per se did not induce fluid secretion . The phenotype of the challenge inoculum influenced fluid secretion; young log-phase organisms induced fluid secretion with a higher frequency than overnight cultures . These findings support earlier evidence implicating leucocytes in an interactive but not exclusive role in the genesis of salmonella-induced fluid secretion . They suggest, though do not prove, that interaction of leucocytes with the appropriate phenotype of organisms results in the release of a host-derived or bacterial secretagogue, or both . The bacterial factor may or may not be the antigen related to cholera toxin, described previously. J Bacteriol, 1989 Oct, 171(10), 5620 - 9 Genetic and biochemical analysis of the MetR activator-binding site in the metE metR control region of Salmonella typhimurium; Urbanowski ML et al.; The Salmonella typhimurium metE and metR genes share a common control region, with overlapping, divergently transcribed promoters . A double gene fusion was constructed in which the metE promoter directs expression of the Escherichia coli lacZ gene and the metR promoter directs expression of the E . coli galK gene . By using an E . coli strain lysogenized with a lambda bacteriophage carrying the metE-lacZ metR-galK double fusion (lambda Elac.Rgal), two classes of cis-acting mutations were isolated that increase metR-galK expression . The first class of mutations causes a simultaneous decrease in metE-lacZ expression by disrupting the normal MetR-mediated activation of the metE promoter . The mutations are located within a region extending from 17 to 34 base pairs upstream of the -35 region of the metE promoter . Gel mobility shift assays and DNaseI protection experiments demonstrated that the MetR protein specifically binds to a 24-base-pair region encompassing these mutations . The second class of mutations increases metR-galK expression by directly altering the promoter consensus sequences of the metE and metR promoters. J Bacteriol, 1989 Oct, 171(10), 5581 - 6 Nucleotide sequences of dnaE, the gene for the polymerase subunit of DNA polymerase III in Salmonella typhimurium, and a variant that facilitates growth in the absence of another polymerase subunit; Lancy ED et al.; The dnaE gene of Salmonella typhimurium, like that of Escherichia coli, encodes the alpha subunit containing the polymerase activity of the principal replicative enzyme, DNA polymerase III . This gene, or one nearby, has been identified as the locus of suppressor mutations that promote growth by cells deleted for dnaQ, the gene for the editing subunit of this enzyme complex . Using a combination of nucleotide sequencing and marker rescue experiments, the alteration in one such suppressor was identified as a valine-to-glycine substitution at amino acid 832 of the 1,160-amino-acid alpha polypeptide . The alpha polypeptides of E . coli and S . typhimurium are identical in size and in 97% of their amino acid residues . Their identity includes the valine residue that was changed in the suppressor allele of S . typhimurium . We also localized a temperature-sensitive dnaE mutation to the 3' half of dnaE. J Bacteriol, 1989 Oct, 171(10), 5436 - 42 Pyrimidine regulation of tandem promoters for carAB in Salmonella typhimurium; Lu CD et al.; The carAB operon of Salmonella typhimurium encodes the two subunits of the enzyme carbamoylphosphate synthetase . Transcription of the operon is initiated at tandem promoters that are subject to control by pyrimidines and arginine . Pyrimidine regulation was examined by quantitative primer extension experiments under conditions in which densitometric measurements of the transcripts were linear with the amount of RNA . RNA was obtained from mutant strains that permit manipulations of pyrimidine nucleotide pools . The data showed that a uridine nucleotide repressed the upstream promoter (Pl), whereas arginine repressed the downstream promoter (P2) . Exogenous cytidine, which increased the intracellular CTP pool in certain mutant strains, did not affect either promoter . However, CTP limitation resulted in derepression of the pyrimidine-specific promoter as well as the downstream arginine-specific promoter . The effect of pyrimidines on P2 was confirmed in a carA::lacZ transcriptional fusion in which the activity of the pyrimidine-specific promoter was abolished . Primer extension experiments with an argR::Tn10 derivative showed that repression of Pl by uridine nucleotides did not require a functional arginine repressor and that repression of P2 by arginine did not interfere with elongation of transcripts initiated at the upstream Pl promoter. J Bacteriol, 1989 Oct, 171(10), 5339 - 46 Cloning and nucleotide sequence of DNA mismatch repair gene PMS1 from Saccharomyces cerevisiae: homology of PMS1 to procaryotic MutL and HexB; Kramer W et al.; The PMS1 gene from Saccharomyces cerevisiae, implicated in DNA mismatch repair in yeast cells (M . S . Williamson, J . C . Game, and S . Fogel, Genetics 110:609-646, 1985), was cloned, and the nucleotide sequence was determined . The nucleotide sequence showed a 2,712-base-pair open reading frame; the predicted molecular mass of the deduced protein is 103 kilodaltons . Deletion mutants of the open reading frame were constructed and genetically characterized . The deduced amino acid sequence of the PMS1 gene exhibited homology to those of the mutL gene from Salmonella typhimurium and the hexB gene from Streptococcus pneumoniae, genes required for DNA mismatch repair in these organisms . The homology suggests an evolutionary relationship of DNA mismatch repair in procaryotes and eucaryotes. J Bacteriol, 1989 Oct, 171(10), 5332 - 8 Nucleotide sequence of the Streptococcus pneumoniae hexB mismatch repair gene: homology of HexB to MutL of Salmonella typhimurium and to PMS1 of Saccharomyces cerevisiae; Prudhomme M et al.; The Hex mismatch repair system of Streptococcus pneumoniae acts both during transformation (a recombination process that directly produces heteroduplex DNA) to correct donor strands and after DNA replication to remove misincorporated nucleotides . The hexB gene product is one of at least two proteins required for mismatch repair in this organism . The nucleotide sequence of a 2.7-kilobase segment from the S . pneumoniae chromosome that includes the 1.95-kilobase hexB gene was determined . The gene encodes a 73.5-kilodalton protein (649 residues) . The spontaneous hex Rx chromosomal mutant allele with which a mutator phenotype has been associated is shown to result from a single base substitution (TAC to TAA) leading to a truncated HexB polypeptide (484 residues) . The HexB protein is homologous to the MutL protein, which is required for methyl-directed mismatch repair in Salmonella typhimurium and Escherichia coli, and to the PMS1 gene product, which is likely to be involved in a mismatch correction system in Saccharomyces cerevisiae . The conservation of HexB-like proteins among procaryotic and eucaryotic organisms indicates that these proteins play an important common role in the repair process . This finding also suggests that the Hex, Mut, and PMS systems evolved from a common ancestor and that functionally similar mismatch repair systems could be widespread among procaryotic as well as eucaryotic organisms. J Bacteriol, 1989 Oct, 171(10), 5325 - 31 Nucleotide sequence of the Salmonella typhimurium mutL gene required for mismatch repair: homology of MutL to HexB of Streptococcus pneumoniae and to PMS1 of the yeast Saccharomyces cerevisiae; Mankovich JA et al.; The mutL gene of Salmonella typhimurium LT2 is required for dam-dependent methyl-directed DNA mismatch repair . We have cloned and sequenced the mutL gene of S . typhimurium LT2 and compared its sequence with those of the hexB gene product of the gram-positive bacterium Streptococcus pneumoniae and the PMS1 gene product of the yeast Saccharomyces cerevisiae . MutL was found to be quite similar to the HexB mismatch repair protein of S . pneumoniae and to the mismatch repair protein PMS1 of the yeast S . cerevisiae . The significant similarities among these proteins were confined to their amino-terminal regions and suggest common evolution of the mismatch repair machinery in those organisms . The DNA sequence for mutL predicted a gene encoding a protein of 618 amino acid residues with a molecular weight of 67,761 . The assignment of reading frame was confirmed by the construction of a chimeric protein consisting of the first 30 amino acids of LacZ fused to residues 53 through 618 of MutL . Interestingly, the presence of excess amounts of this fusion protein in wild-type mutL+ cells resulted in a trans-dominant effect causing the cell to exhibit a high spontaneous mutation frequency. Carcinogenesis, 1989 Oct, 10(10), 1953 - 5 Modulating effect of plant flavonoids on the mutagenicity of N-methyl-N'-nitro-N-nitrosoguanidine; Francis AR et al.; Tests have been carried out with several plant flavonoids to detect their ability to suppress mutagenesis in Salmonella typhimurium strain TA100 NR induced by the direct-acting carcinogen N-methyl-N'-nitro-N-nitrosoguanidine . Among the most effective flavonoids are the isoflavone, biochanin A, the flavanone glycoside, naringin, and its aglycone, naringenin, and several flavonols, e.g . morin, fisetin, kaempferol, gossypetin and quercetin, including a flavonol glycoside, rutin . In particular, naringin possesses exceptional antimutagenic activity, in as much as, less than half the equimolar amount can reduce the mutagenic potency of this carcinogen by 50% . These flavonoids appear to act either by preventing passage of the carcinogen into bacterial cells or by altering some cellular processes. Mutat Res, 1989 Oct, 224(2), 229 - 33 Evaluation of the mutagenicity and the tumor-promoting activity of parasite extracts: Schistosoma japonicum and Clonorchis sinensis; Ishii A et al.; In relation to the observed association of carcinogenesis with parasitic infections, the mutagenicity of extracts of Schistosoma japonicum and Clonorchis sinensis was examined . In the bacterial mutagenicity tests using the Ames Salmonella typhimurium strains TA98, TA100, TA97 and TA102, and Escherichia coli WP2 and WP2 uvrA pKM101 Schistosoma soluble egg antigen and a homogenate of adult Schistosoma worms showed no positive responses either in the presence or in the absence of S9 mix . Likewise, adult worm extracts of Clonorchis showed no mutagenicity . The Schistosoma soluble egg antigen showed a weak but significant activity for the induction of Epstein-Barr virus expression in viral genome-carrying human lymphoblastoid cells in culture . This phenomenon suggests that the soluble egg antigen possesses tumor-promoting activity. J Bacteriol, 1989 Oct, 171(10), 5572 - 80 Isolation and characterization of mutants with deletions in dnaQ, the gene for the editing subunit of DNA polymerase III in Salmonella typhimurium; Lancy ED et al.; dnaQ (mutD) encodes the editing exonuclease subunit (epsilon) of DNA polymerase III . Previously described mutations in dnaQ include dominant and recessive mutator alleles as well as leaky temperature-sensitive alleles . We describe the properties of strains bearing null mutations (deletion-substitution alleles) of this gene . Null mutants exhibited a growth defect as well as elevated spontaneous mutation . As a consequence of the poor growth of dnaQ mutants and their high mutation rate, these strains were replaced within single colonies by derivatives carrying an extragenic suppressor mutation that compensated the growth defect but apparently not the mutator effect . Sixteen independently derived suppressors mapped in the vicinity of dnaE, the gene for the polymerization subunit (alpha) of DNA polymerase III, and one suppressor that was sequenced encoded an altered alpha polypeptide . Partially purified DNA polymerase III containing this altered alpha subunit was active in polymerization assays . In addition to their dependence on a suppressor mutation affecting alpha, dnaQ mutants strictly required DNA polymerase I for viability . We argue from these data that in the absence of epsilon, DNA replication falters unless secondary mechanisms, including genetically coded alteration in the intrinsic replication capacity of alpha and increased use of DNA polymerase I, come into play . Thus, epsilon plays a role in DNA replication distinct from its known role in controlling spontaneous mutation frequency. Bioorg Khim, 1989 Oct, 15(10), 1375 - 83 {Synthesis of cytidine diphosphate-3,6-dideoxyhexoses--donors of glycosyl residues in the biosynthesis of O-specific polysaccharides of Salmonella of serogroups A, B and C}; Utkina NS et al.; Interaction of lithium alcoholates of 2,4-di-O-benzoates of paratose and abequose with tetrabenzyl pyrophosphate gave alpha-phosphates of the 3,6-dideoxyhexoses, further converted into the corresponding cytidine-5'-diphosphate derivatives . These synthetic nucleotides were shown to participate in the biosynthesis of the O-specific polysaccharides for Salmonella typhimurium and S . nitra. J Biol Chem, 1989 Sep 25, 264(27), 15796 - 808 Characterization of the flavoprotein moieties of NADPH-sulfite reductase from Salmonella typhimurium and Escherichia coli . Physicochemical and catalytic properties, amino acid sequence deduced from DNA sequence of cysJ, and comparison with NADPH-cytochrome P-450 reductase; Ostrowski J et al.; NADPH-sulfite reductase flavoprotein (SiR-FP) was purified from a Salmonella typhimurium cysG strain that does not synthesize the hemoprotein component of the sulfite reductase holoenzyme . cysJ, which codes for SiR-FP, was cloned from S . typhimurium LT7 and Escherichia coli B, and both genes were sequenced . Physicochemical analyses and deduced amino acid sequences indicate that SiR-FP is an octamer of identical 66-kDa peptides and contains 4 FAD and 4 FMN per octamer . Potentiometric titrations of SiR holoenzyme, SiR-FP, and FMN-depleted SiR-FP yielded the following redox potentials for the prosthetic groups at pH 7.7: E'1 (FMNH./FMN) = -152 mV; E'2 (FMNH2/FMNH.) = -327 mV; E'3 (FADH./FAD) = -382 mV; E'4 (FADH2/FADH.) = -322 mV . Microcoulometric titration of SiR-FP at 25 degrees C yielded data which were in full agreement with these potentials . Spectroscopic and catalytic studies of native SiR-FP and of SiR-FP depleted of FMN support the following electron flow sequence: NADPH----FAD----FMN . FMN can then contribute electrons to the hemoprotein component of sulfite reductase, as well as to cytochrome c and various diaphorase acceptors . The FMN is postulated to cycle between the FMNH2 and FMNH . oxidation states during catalysis; in this sense SiR-FP shares a catalytic mechanism with NADPH-cytochrome P-450 oxidoreductase . SiR-FP domains involved in binding FMN, FAD, and NADPH are proposed from amino acid sequence homologies with Desulfovibrio vulgaris flavodoxin (Dubourdieu, M., and Fox, J.L . (1977) J . Biol . Chem . 252, 1453-1463) and spinach ferredoxin-NADP+ oxidoreductase (Karplus, P.A., Walsh, K.A., and Herriott, J . R . (1984) Biochemistry 23, 6576-6583) . Comparison of the deduced amino acid sequences of SiR-FP and NADPH-cytochrome P-450 oxidoreductase (Porter, T . D., and Kasper, C.B . (1985) Proc . Natl . Acad . Sci . U . S.A . 82, 973-977) also showed identities that suggest these two proteins are descended from a common precursor, which contained binding regions for both FMN and FAD. J Biol Chem, 1989 Sep 25, 264(27), 15774 - 80 Microspectrophotometric studies on single crystals of the tryptophan synthase alpha 2 beta 2 complex demonstrate formation of enzyme-substrate intermediates; Mozzarelli A et al.; Microspectrophotometry of single crystals of the tryptophan synthase alpha 2 beta 2 complex from Salmonella typhimurium is used to compare the catalytic and regulatory properties of the enzyme in the soluble and crystalline states . Polarized absorption spectra demonstrate that chromophoric intermediates are formed between pyridoxal phosphate at the active site of the beta subunit and added substrates, substrate analogs, and reaction intermediate analogs . Although the crystalline and soluble forms of the enzyme produce some of the same enzyme-substrate intermediates, including Schiff base and quinonoid intermediates, in some cases the equilibrium distribution of these intermediates differs in the two states of the enzyme . Ligands which bind to the active site of the alpha subunit alter the distribution of intermediates formed at the active site of the beta subunit in both the crystalline and soluble states . The three-dimensional structures of the tryptophan synthase alpha 2 beta 2 complex and of a derivative with indole-3-propanol phosphate bound at the active site of the alpha subunit have recently been reported (Hyde, C . C., Ahmed, S . A., Padlan, E . A., Miles, E . W., and Davies, D . R . (1988) J . Biol . Chem . 264, 17857-17871) . Our present findings help to establish experimental conditions for selecting defined intermediates for future x-ray crystallographic analysis of the alpha 2 beta 2 complex with ligands bound at the active sites of both alpha and beta subunits . These crystallographic studies should explain how catalysis occurs at the active site of the beta subunit and how the binding of a ligand to one active site affects the binding of a ligand to the other active site which is 25 A away. Nature, 1989 Sep 21, 341(6239), 245 - 8 Adaptive eradication of methionine and cysteine from cyanobacterial light-harvesting proteins; Mazel D et al.; Sulphur is unique among the main elements of living cells in that it is covalently bound to biopolymers but does not occur in the biopolymer backbone . Indeed, most of the bacterial sulphur content resides in the methionine and cysteine side-chains of proteins . The growth yield of an organism under conditions of sulphur limitation could therefore be greatly enhanced by mutations that substitute Met and Cys in the organism's proteins for sulphur-free amino acids . Because the saving in sulphur would increase with such accumulating mutations, Met and Cys changes could be progressively selected . Abundant proteins should be the prime targets of such a selection . A few published observations give credence to this scenario . Sulphate permease, which is abundantly produced by sulphur-starved Salmonella typhimurium, lacks Met and Cys residues . Also, two species of marine purple bacteria synthesize more protein than can be expected from a limited sulphate supply . We now report that the cyanobacterium Calothrix sp . PCC 7601 (referred to here as Calothrix) encodes sulphur-depleted versions of its most abundant proteins--phycocyanin and its auxiliary polypeptides--which it specifically expresses under conditions of sulphur limitation . Although these proteins do not take part in the fixation of sulphur, their elevated synthesis affects the sulphur budget of cyanobacterial cells . Direct evidence is thus provided that the structure of macromolecules can be subject to metabolic optimization. J Biol Chem, 1989 Sep 15, 264(26), 15726 - 37 Characterization of the cysJIH regions of Salmonella typhimurium and Escherichia coli B . DNA sequences of cysI and cysH and a model for the siroheme-Fe4S4 active center of sulfite reductase hemoprotein based on amino acid homology with spinach nitrite reductase; Ostrowski J et al.; The hemoprotein component of Salmonella typhimurium sulfite reductase (NADPH) (EC 1.8.1.2) was purified to homogeneity from cysJ266, a mutant strain lacking sulfite reductase flavoprotein . The siroheme- and Fe4S4-containing enzyme was isolated as a monomeric 63-kDa polypeptide and consisted of a mixture of unligated enzyme and a complex with sulfite . Following reduction with 5'-deazaflavin-EDTA and reoxidation, the complex was converted to the uncomplexed, high spin ferri-siroheme state seen previously with Escherichia coli sulfite reductase hemoprotein preparations . The S . typhimurium hemoprotein exhibited catalytic and physical properties identical to the hemoprotein prepared by urea dissociation of E . coli sulfite reductase holoenzyme and was fully competent in reconstituting NADPH-sulfite reductase activity when combined with excess purified sulfite reductase flavoprotein . The DNA sequences of cysI and cysH from S . typhimurium and E . coli B were determined and, together with previously reported data, confirmed the organization of this region as promoter-cysJ-cysI-cysH with all three genes oriented in the same direction from the promoter . Molecular weights deduced for the cysI-encoded sulfite reductase hemoprotein and for the cysH-encoded 3'-phosphoadenosine 5'-phosphosulfate sulfotransferase were approximately 64,000 and 28,000, respectively . Comparison of the deduced amino acid sequence of sulfite reductase hemoprotein with that of spinach nitrite reductase (Back, E., Burkhart, W., Moyer, M., Privalle, L., and Rothstein, S . (1988) Mol . Gen . Genet . 212, 20-26), which also contains siroheme and an Fe4S4 cluster, showed two groups of cysteine-containing sequences with the structures Cys-(X)3-Cys and Cys-(X)5-Cys, which are homologous in the two enzymes and are postulated to provide the ligands of the Fe4S4 cluster in both proteins . From these sequences and from crystallographic (McRee, D . E., Richardson, D . C., Richardson, J . S., and Siegel, L . M . (1986) J . Biol . Chem . 261, 10277-10281) and spectroscopic data in the literature, a model is proposed for the structure of the active center of these two enzymes. Cancer Lett, 1989 Sep 15, 47(1-2), 37 - 44 Effect of tannic acid on rat liver S9 mediated mutagenesis, metabolism and DNA binding of benzo{a}pyrene; Vance RE et al.; Tannic acid, a naturally occurring plant phenol, inhibited rat liver S9 mediated mutagenesis of benzo{a}pyrene in Salmonella typhimurium by 32-77% at concentrations of 5-50 micrograms/mutagenesis plate . Tannic acid (10-40 microM) had no affect on the formation of organosoluble metabolites of benzo{a}pyrene or of its water-soluble conjugates . It did, however, inhibit benzo{a}pyrene (B{a}P) metabolite binding to calf thymus DNA by 40% at a concentration of 40 microM and inhibited benzo{a}pyrene 7,8-dihydrodiol-9,10-epoxide (BPDE): deoxyguanosine adduct formation in calf thymus DNA by 12-54% at concentrations of 10-40 microM . These results suggest that the antimutagenic effect of tannic acid and inhibition of B{a}P metabolite binding to DNA is by a previously described scavenging mechanism and/or by a DNA-affinity binding mechanism that prevents BPDE interaction with DNA as previously described for ellagic acid. J Mol Biol, 1989 Sep 5, 209(1), 127 - 33 Terminal regions of flagellin are disordered in solution; Vonderviszt F et al.; Limited proteolysis of flagellin from Salmonella typhimurium SJW1103 by subtilisin, trypsin and thermolysin results in homologous degradation patterns . The terminal regions of flagellin are very sensitive to proteolysis . These parts are degraded into small oligopeptides at the very early stage of a mild digestion that yields a relatively stable fragment with a molecular weight of 40,000 . Further proteolytic degradation results in a stable 27,000 Mr fragment . The 40,000 Mr tryptic fragment has been identified as residues 67 to 446 of the flagellin sequence, while the 27,000 Mr fragment involves the 179 to 418 segment . The NH2-terminal sequence positions for the corresponding fragments produced by subtilisin are 60 and 174 for the 40,000 Mr and 27,000 Mr fragments, respectively . The fragments lost their polymerizing ability . Structural properties of flagellin and its 40,000 Mr tryptic fragment were compared by circular dichroism spectroscopy and differential scanning calorimetry . Analysis of the calorimetric melting profiles suggests that terminal parts of flagellin have no significant internal stability and they are in extensive contact with water . However, these regions contain some secondary structure, probably alpha-helices, as revealed by comparison of the circular dichroic spectra in the far-ultraviolet region . Our results indicate that, although the terminal regions of flagellin may contain some alpha-helical secondary structure of marginal stability, they have no compact ordered tertiary structure in solution . On the contrary, the central region of the molecule involves at least two compact structural units. J Biol Chem, 1989 Sep 5, 264(25), 14716 - 22 Inhibition of lipopolysaccharide O-antigen synthesis by colicin M; Harkness RE et al.; Colicin M inhibits peptidoglycan biosynthesis at the level of the bactoprenyl carrier lipid . Since the synthesis of O-antigen also requires bactoprenyl carrier lipid, the effect of colicin M on O-antigen biosynthesis was studied using a colicin-sensitive strain of Salmonella typhimurium . Determination of O-antigen intermediates by two different methods showed that bactoprenyl-dependent O-antigen biosynthesis was inhibited by colicin M . Synthesis of both O-antigen and peptidoglycan was almost immediately inhibited following colicin addition . This was followed some 20 min later by cell lysis . The only known common step between O-antigen and peptidoglycan synthesis is formation of bactoprenyl phosphate by dephosphorylation of bactoprenyl pyrophosphate . Determination of bactoprenyl phosphates showed an accumulation of bactoprenyl pyrophosphate in colicin-treated cultures . It was concluded that dephosphorylation of the bactoprenyl lipid carrier was inhibited by colicin M, and this in turn prevented both O-antigen and peptidoglycan synthesis. Immunol Lett, 1989 Sep, 22(3), 195 - 8 The absence of direct antimicrobial activity in extracts of cytotoxic lymphocytes; Joag S et al.; An important mechanism used by the immune system in resisting infections by intracellular pathogens is the destruction of host cells by cytolytic lymphocytes . Whether these lymphocytes display a more direct antimicrobial action remains unclear . We have attempted to answer this question by testing extracts of cytolytic lymphocytes, prepared by cell fractionation, against three bacterial species - Escherichia coli, Salmonella typhimurium, and Listeria monocytogenes . We also tested these extracts against two viruses - pseudorabies virus and vesicular stomatitis virus . The extracts showed negligible activity against the test organisms under the conditions used. Gene, 1989 Sep 1, 81(1), 73 - 82 Molecular characterization of TRP1, a gene coding for tryptophan synthetase in the basidiomycete Coprinus cinereus; Skrzynia C et al.; We utilized a cloned gene (TRP5) encoding tryptophan synthetase (TSase) from Saccharomyces cerevisiae to identify and clone the corresponding gene (TRP1) from the basidiomycete Coprinus cinereus . The primary nucleotide (nt) sequence of this gene was determined and compared to sequences from other filamentous fungi, as well as to other genes coding for TSase . A transformation assay was used to demonstrate that 321 nt, which do not include CAAT or TATAAA elements and precede the translation initiation codon, are sufficient for expression in a variety of chromosomal locations . The coding region (2584 nt) is interrupted at nine positions, and putative splicing signals (5'-GTRNGT...YAG-3') are present in each case . The predicted translation product contains 702 amino acids (aa) and is very similar to other TSases, except in the region of aa 257-296 that connects the alpha and beta functional domains . Both the number and the identity of the aa differ in this region between C . cinereus . S . cerevisiae, and Neurospora crassa . Comparison of exon boundaries in the C . cinereus sequence to the three-dimensional structure of Salmonella typhimurium TSase indicates that there is no simple correlation between exons and major functional domains in this protein. FEMS Microbiol Rev, 1989 Sep, 5(3), 265 - 76 Peptidases and proteases of Escherichia coli and Salmonella typhimurium; Lazdunski AM; A number of peptidases and proteases have been identified in Escherichia coli . Although their specific physiological roles are often not known, some of them have been shown to be involved in: the maturation of nascent polypeptide chains; the maturation of protein precursors; the signal peptide processing of exported proteins; the degradation of abnormal proteins; the use of small peptides as nutrients; the degradation of colicins; viral morphogenesis; the inactivation of some regulatory proteins for which a limited lifetime is a physiological necessity . Some of these enzymes act in concert to carry out specific functions . At present, twelve peptidases and seventeen proteases have been characterized . The specificity for only a few of them is known . The possible roles and the properties of these enzymes are discussed in this review. J Gen Microbiol, 1989 Sep, 135 ( Pt 9), 2561 - 7 Transformation in restriction-deficient Salmonella typhimurium LT2; Tsai SP et al.; Stable restriction-deficient, modification-proficient galE (JR501) and F'galE+ (JR502) strains of Salmonella typhimurium were constructed and the effects of restriction on transformation by plasmid pBR322 were tested . Several factors which affect transformation efficiency were systematically examined to determine optimum transformation conditions and a simplified method is presented. Microb Pathog, 1989 Sep, 7(3), 165 - 73 Identification and genetic analysis of mkaA--a gene of the Salmonella typhimurium virulence plasmid necessary for intracellular growth; Taira S et al.; Salmonella typhimurium, like many other Salmonella serovars, harbours a large plasmid required for mouse virulence and growth of bacteria in host cells . The nature of one virulence-abolishing Tn5 insertion (zzx-2556::Tn5) in the plasmid was characterized . A 3.7 kb insert harbouring this region was cloned in pBR325 . Plasmid-directed protein synthesis in minicells indicated that the transposon had eliminated the expression of a 70 kDa protein encoded by the virulence plasmid . Nucleotide sequence analysis of the corresponding wild type DNA region showed a 1773 bp open reading frame (mkaA), encoding a protein of 591 amino acid residues and a predicted molecular mass of 60.6 kDa; zzx-2556::Tn5 was situated within mkaA. J Nat Prod, 1989 Sep-Oct, 52(5), 1118 - 27 Abrusosides A-D, four novel sweet-tasting triterpene glycosides from the leaves of Abrus precatorius; Choi YH et al.; In addition to abrusoside A {1}, abrusosides B {2}, C {3}, and D {4}, three further sweet glycosides based on the novel cycloartane-type aglycone, abrusogenin {5}, were isolated from an n-BuOH-soluble extract of the leaves of Abrus precatorius . Using a combination of spectral methods, the structures of compounds 1-4 were assigned, respectively, as the 3-O-beta-D-glucopyranosyl, the 3-O-beta-D-glucopyranosyl-(1----2)-beta-D-6-methylglucuronopyranosyl+ ++, the 3-O-beta-D-glucopyranosyl-(1----2)-beta-D-glucopyranosyl, and the 3-O-beta-D-glucopyranosyl-(1----2)-beta-D-glucuronopyranosyl derivatives of compound 5 . After it established that compounds 1-4 were neither acutely toxic with mice nor mutagenic with Salmonella typhimurium strain TM677, they were found by a human taste panel to exhibit sweetness potencies in the range 30-100 times greater than sucrose. J Nat Prod, 1989 Sep-Oct, 52(5), 1092 - 9 Plant antimutagenic agents, 7 . Structure and antimutagenic properties of cymobarbatol and 4-isocymobarbatol, new cymopols from green alga (Cymopolia barbata); Wall ME et al.; Two new compounds, cymobarbatol and 4-isocymobarbatol, were isolated from the marine alga Cymopolia barbata . The complete structures and absolute stereochemistries of these compounds were elucidated by a variety of spectroscopic techniques and X-ray crystallography . Both compounds were found to be nontoxic over a broad concentration range to Salmonella typhimurium strains T-98 and T-100 . Both compounds exhibited strong inhibition of the mutagenicity of 2-aminoanthracene and ethyl methanesulfonate toward, respectively, the T-98 strain plus a metabolic activator and T-100. Infection, 1989 Sep-Oct, 17(5), 306 - 8 Salmon