J Antimicrob Chemother, 1986 Oct, 18 Suppl C, 175 - 7 R plasmids in Salmonella typhimurium in the United Kingdom; Threlfall EJ et al.; In the United Kingdom, R plasmids are common in bovine-associated phage types of Salmonella typhimurium and in particular in strains of phage type 204c (DT204c); all strains of this type carry at least three R plasmids . Gentamicin resistance appeared in DT204c in 1983 and plasmids conferring resistance to gentamicin also code for resistance to apramycin . Three types of apramycin-gentamicin resistance plasmid have been identified. Appl Environ Microbiol, 1986 Oct, 52(4), 718 - 22 Mutagenicity of the Alternaria metabolites altertoxins I, II, and III; Stack ME et al.; The Ames Salmonella typhimurium assay was used to demonstrate that an extract of the mold Alternaria alternata was mutagenic . The mutagenic extract was fractionated, and the Ames test was used to determine which fractions were mutagenic . Subsequently, altertoxins I and II and a new compound referred to as altertoxin III were isolated by liquid chromatography and shown to be hydroxyperylenequinone compounds by mass spectrometry and infrared, ultraviolet, and proton magnetic resonance spectroscopy . Altertoxins I, II, and III were mutagenic to S . typhimurium TA98, TA100, and TA1537 with and without metabolic activation. Proc Natl Acad Sci U S A, 1986 Oct, 83(19), 7157 - 61 Restoration of flagellar clockwise rotation in bacterial envelopes by insertion of the chemotaxis protein CheY; Ravid S et al.; When cells of the bacterium Salmonella typhimurium are incubated with penicillin and lysed in a dilute buffer, flagellated cytoplasm-free envelopes are formed . When the envelopes are tethered to glass by their flagella and then energized, some of them spin . The direction of rotation of wild-type envelopes is exclusively counterclockwise (CCW) . We perturbed this system by including in the lysis medium (and hence in the envelopes) the chemotaxis protein CheY . As a result, some of the envelopes rotated exclusively clockwise (CW) . The fraction of envelopes that did so increased with the concentration of CheY; at a concentration of 48 microM (pH 8), all functional envelopes spun CW . The fraction also increased with the pH of the lysis medium in the range of 6.6-8.4 . The results were the same in the presence or absence of intracellular Ca2+ . Reconstituted envelopes failed to respond to chemotactic stimuli . None of them changed the direction of their rotation . However, when the intracellular pH was lowered to 6.6 or below, envelopes that spun CW stopped rotating, while envelopes that spun CCW continued to rotate . This phenomenon was reversible . We conclude that CheY per se, without any additional free cytoplasmic mediators, interacts with a switch at the base of the flagellum to cause CW rotation. Mutat Res, 1986 Oct, 175(2), 51 - 9 Aspects of chloroquine mutagenicity; Obaseiki-Ebor EE et al.; Using the Ames plate reversion and fluctuation tests, the mutagenic activity of chloroquine was tested in the new tester strains of Salmonella typhimurium, TA97, TA102, and Escherichia coli strains WP2, WP2hcr, WP6 and WP67 . The E . coli transconjugants obtained from the mating transfer of R-plasmid(s) in strains TA97 and TA102 respectively to E . coli WP2, i.e . EE97 and EE102, were also tested . Chloroquine reverted strain TA97 from histidine dependence to independence and also reverted E . coli strains EE97 and EE102 from tryptophan dependence to independence . The E . coli strains WP2, WP2hcr; WP6 and WP67 and S . typhimurium TA102 were not affected . S . typhimurium TA97 could be reverted with 250 ng/ml of chloroquine (therapeutic blood level of chloroquine is 300 ng/ml) . Reversion generally occurred optimally at the relatively lower concentrations of chloroquine i.e . 25, 50 micrograms/ml than at higher concentrations . From the properties of the reverted tester strains, the results indicated that chloroquine per se mediated frameshift reversion. Mutat Res, 1986 Oct, 172(1), 37 - 45 Xanthine oxidase-mediated mutagenicity of the bladder carcinogen 4-nitrobiphenyl; Swaminathan S et al.; Xanthine oxidase catalyzed mutagenicity of 4-nitrobiphenyl (NBP), a dog-bladder carcinogen, was tested in Ames assay using Salmonella typhimurium TA98 strains . NBP was active as a mutagen in the parent strain TA98 which is proficient in nitroreductase, while it was inactive in the strain TA98NR which is deficient in nitroreductase . However, preincubation of NBP at 37 degrees C with NADH and commercial preparations of xanthine oxidase for 30 min resulted in a dose-dependent increase in the mutagenic activity in TA98NR . Allopurinol blocked the xanthine oxidase catalyzed mutagenicity of NBP in TA98NR and the extent of inhibition was dependent upon the concentration of the inhibitor . Rat-liver and dog-bladder cytosol preparations also enhanced the mutagenic activity of NBP in TA98NR in a dose-dependent manner . In addition, the cytosol-mediated activity was also inhibited by allopurinol, implying that the cytosolic enzyme activity might be due to xanthine oxidase . In vitro enzymatic reduction of NBP using bacterial cell lysates of TA98 and TA98NR revealed the major product of reduction to be 4-aminobiphenyl . The transient intermediates of reduction were not detected during the in vitro incubation . The reduction intermediate N-hydroxylaminobiphenyl showed direct and equal mutagenic activity in both TA98 and TA98NR, in contrast to NBP . These results suggest that N-hydroxylaminobiphenyl is generated during the preincubation of NBP with xanthine oxidase or cytosolic preparations and the former might account for the mutagenicity of NBP . Furthermore, the occurrence of such enzyme(s) in the target tissue for NBP carcinogenesis, support the hypothesis that metabolic activation of the bladder carcinogen NBP could occur within the target organ by virtue of its intrinsic metabolic potential. Mutat Res, 1986 Oct, 172(1), 29 - 36 Selective mutagenic activity of 2-bromo-propanamides on Salmonella typhimurium . A structure-activity study; Dolzani L et al.; Nineteen 2-halogeno-acetamides, -propanamides, and -iso-butyramides and four related epoxyamides were tested as mutagens for Salmonella typhimurium TA100 . Mutagenic activity was observed in strictly selected 2-halogenoamides and in all epoxyamides . The effectiveness of 2-halogenoamides depends upon: the character of the carbon carrying the halogen (1 degree, 2 degrees, 3 degrees); the nature of the halogen (Br, Cl); the substitution at nitrogen . Some considerations concerning the selectivity observed are presented. Mutat Res, 1986 Oct, 172(1), 19 - 27 Mutagenicity of the photochemical reaction products of pyrene with nitrogen dioxide; Hisamatsu Y et al.; The mutagenicity of the photochemical reaction products of pyrene with nitrogen dioxide (NO2) and the mutagens in them were investigated for the interpretation of their biological significance as genetoxic hazards of polycyclic aromatic hydrocarbons (PAHs) in airborne particles . Samples extracted from the photochemical reaction products of pyrene with NO2 diluted with air using a high-pressure mercury lamp were mutagenic for Salmonella typhimurium strains TA97 and TA98 in the absence of S9 mix, with a trend to detoxification in the presence of the metabolic system . The mutagens in the crude samples extracted from their products, which were fractionated by normal-phase high-performance liquid chromatography (HPLC) on a column of Nucleosil 100-30 with n-hexane-benzene as an eluting solution, were analyzed by HPLC, mass spectrometry and Fourier transform infrared (FT-IR) spectrometry . Based on these results, it was recognized that 1-nitropyrene (1-NP), 1,3-dinitropyrene (1,3-DNP), 1,6-dinitropyrene (1,6-DNP) and 1,8-dinitropyrene (1,8-DNP) was formed by the photochemical reaction of pyrene with NO2 . The yield of DNPs peaked at 2-3 h irradiation. J Bacteriol, 1986 Oct, 168(1), 437 - 9 Cloning and characterization of the gene encoding 3-deoxy-D-manno-octulosonate 8-phosphate synthetase from Escherichia coli; Woisetschlager M et al.; The cloning of the gene for Escherichia coli PL-2 2-keto-3-deoxy-D-manno-octonate 8-phosphate synthetase is reported . Positive transformants showed an increase of approximately three-fold in specific activity of the enzyme both in E . coli and in Salmonella typhimurium as host cells . A subclone containing a 1.5-kilobase PvuII fragment overproduced active enzyme . Minicell experiments that allow the detection of plasmid encoded proteins revealed an insert-coded single protein band of 34 kilodaltons. J Bacteriol, 1986 Oct, 168(1), 420 - 4 Global control in Salmonella typhimurium: two-dimensional electrophoretic analysis of starvation-, anaerobiosis-, and heat shock-inducible proteins; Spector MP et al.; The response of Salmonella typhimurium to various forms of environmental stress was examined by using O'Farrell two-dimensional gel electrophoresis . Polypeptides (a total of 110) which quantitatively increased during various starvations, anaerobiosis, or heat shock were identified and cataloged in reference to a standard polypeptide map . Although significant overlap was noted during comparison of proteins induced by different starvations, only a few proteins produced during heat shock or anaerobiosis were also identified as starvation inducible. J Bacteriol, 1986 Oct, 168(1), 398 - 404 Characterization and physiological roles of membrane-bound hydrogenase isoenzymes from Salmonella typhimurium; Sawers RG et al.; We found that Salmonella typhimurium strain LT2 (Z) possessed two immunologically distinct, membrane-bound hydrogenase isoenzymes, which were similar in electrophoretic mobilities and apoprotein contents to hydrogenase isoenzymes 1 and 2 of Escherichia coli . The S . typhimurium enzymes cross-reacted with antibodies raised to the respective hydrogenase isoenzymes of E . coli . As for E . coli, an additional membrane-bound hydrogenase activity (termed hydrogenase 3), which did not cross-react with antibodies raised against either hydrogenase 1 or 2, was also present in detergent-dispersed membrane preparations . The physiological role of each of the three isoenzymes in E . coli has remained unclear owing to the lack of mutants specifically defective for individual isoenzymes . However, analysis of two additional wild-type isolates of S . typhimurium revealed specific defects in their hydrogenase isoenzyme contents . S . typhimurium LT2 (A) lacked isoenzyme 2 but possessed normal levels of hydrogenases 1 and 3 . S . typhimurium LT7 lacked both isoenzymes 1 and 2 but retained normal hydrogenase 3 activity . Characterization of hydrogen metabolism by these hydrogenase-defective isolates allowed us to identify the physiological role of each of the three isoenzymes . Hydrogenase 3 activity correlated closely with formate hydrogenlyase-dependent hydrogen evolution, whereas isoenzyme 2 catalyzed hydrogen uptake (oxidation) during anaerobic, respiration-dependent growth . Isoenzyme 1 also functioned as an uptake hydrogenase but only during fermentative growth . We postulate that this enzyme functions in a hydrogen-recycling reaction which operates during fermentative growth. J Bacteriol, 1986 Oct, 168(1), 389 - 97 Two genetically distinct pathways for transcriptional regulation of anaerobic gene expression in Salmonella typhimurium; Jamieson DJ et al.; Expression of the tripeptide permease gene tppB is anaerobically induced . This induction is independent of the fnr (oxrA) gene product, which is known to be required for the anaerobic induction of several respiratory enzymes . We isolated, characterized, and mapped mutations in two genes, oxrC and tppR, which prevent the anaerobic induction of tppB expression . Mutations in oxrC were highly pleiotropic, preventing the anaerobic expression of the formate dehydrogenase component of formate hydrogen lyase (fhl), a tripeptidase (pepT), and two of the three known hydrogenase isoenzymes (hydrogenases 1 and 3) . On the other hand, expression of nitrate reductase, fumarate reductase, and a number of other fnr (oxrA)-dependent enzymes was not affected by mutations in oxrC . Thus, there appeared to be at least two distinct classes of anaerobically induced genes, those which required fnr for their expression and those which required oxrC . It seems that fnr-dependent enzymes perform primarily respiratory functions, whereas oxrC-dependent enzymes served fermentative or biosynthetic roles . We found the primary defect of oxrC mutants to be a deficiency in phosphoglucose isomerase activity, implying that a product of glycolysis functions as an anaerobic regulatory signal . Mutations in tppR were specific for tppB and did not affect expression of other oxrC-dependent genes . However, tppR did exhibit phenotypes other than the regulation of tppB . Both oxrC and tppR mutants were hypersensitive to the toxic NAD analog 6-aminonicotinic acid . This suggests that oxrC and tppR may play a role in the regulation of NAD biosynthesis or, alternatively, that NAD or a related nucleotide serves as the anaerobic signal for oxrC-dependent enzymes. J Bacteriol, 1986 Oct, 168(1), 328 - 33 Control of lipopolysaccharide biosynthesis and release by Escherichia coli and Salmonella typhimurium; Ishiguro EE et al.; The influence of the relA gene on lipopolysaccharide (LPS) biosynthesis and release by Escherichia coli and Salmonella typhimurium was investigated . Similar results were obtained with both species . The incorporation of {3H}galactose into LPS by galE mutants was inhibited by at least 50% (as compared with normal growing controls) during amino acid deprivation of relA+ strains . This inhibition could be prevented by the treatment of the amino acid-deprived relA+ bacteria with chloramphenicol, a known antagonist of the stringent control mechanism . Furthermore, LPS biosynthesis was not inhibited during amino acid deprivation of isogenic relA mutant strains . These results indicate that LPS synthesis is regulated by the stringent control mechanism . Normal growing cells of both relA+ and relA strains released LPS into the culture fluid at low rates . Amino acid deprivation stimulated the rate of LPS release by relA mutants but not by relA+ bacteria . Chloramphenicol treatment markedly stimulated the release of cell-bound LPS by amino acid-deprived relA+ cells . Thus, a low rate of LPS release was characteristic of normal growth and could be increased in nongrowing cells by relaxing the control of LPS synthesis. J Bacteriol, 1986 Oct, 168(1), 322 - 7 Cloning and characterization of the cysAMK region of Salmonella typhimurium; Hulanicka MD et al.; A total of 30 kilobases of DNA comprising the cysAMK region of S . typhimurium was cloned as a series of fragments in phage lambda 1059 . The genetic organization of this region was established through studies of gene expression from fragments subcloned in pBR322 and from blot hydridization analyses of restriction sites in chromosomal DNA from multisite deletion strains . The results give a gene order of cysA-cysM-crr-ptsl-ptsH-cysK over a distance of approximately 12 kilobases . cysM and cysA have been cloned and expressed in pBR322; attempts to obtain stable pBR322 derivatives carrying cysK were unsuccessful. J Bacteriol, 1986 Oct, 168(1), 109 - 14 Export of glutathione by some widely used Salmonella typhimurium and Escherichia coli strains; Owens RA et al.; Significant levels of extracellular glutathione (GSH) were detected in aerobically grown cultures of some strains of Salmonella typhimurium LT-2 and in Escherichia coli K-12, B, and B/r but not in cultures of nine freshly isolated clinical isolates of E . coli . Cultures of S . typhimurium generally contained less total GSH (intracellular plus external) than did E . coli cultures . S . typhimurium TA1534 contained about 2 mM intracellular GSH and exported about 30% of its total GSH . The external GSH concentration increased logarithmically during exponential growth and peaked at about 24 microM in early-stationary-phase cultures . External accumulation of GSH was inhibited by 30 mM NaN3 . GSH was predominantly exported in the reduced form . Two-dimensional paper chromatography of supernatants from cultures labeled with Na2(35)SO4 confirmed the presence of GSH and revealed five other sulfur-containing compounds in the media of S . typhimurium and E . coli cultures . The five unidentified compounds were not derivatives of GSH. Infect Immun, 1986 Oct, 54(1), 1 - 8 Protection of C3H/HeJ mice from lethal Salmonella typhimurium LT2 infection by immunization with lipopolysaccharide-lipid A-associated protein complexes; Killion JW et al.; C3H/HeJ mice were immunized intraperitoneally (i.p.) with lipopolysaccharide (LPS)-lipid A-associated protein (LAP) complexes or with purified protein-free LPS prior to lethal i.p . or intravenous Salmonella typhimurium LT2 challenge . Our results demonstrated that these Salmonella-hypersusceptible mice can be effectively protected against 1,000 100% lethal doses of S . typhimurium LT2 (i.e., 1,000 viable bacteria) administered by intravenous challenge when previously immunized with LAP-LPS complexes . In contrast to these results, immunization with LPS afforded markedly less protection regardless of the route of challenge, thus suggesting that the LAP portion of LAP-LPS complexes may be necessary for inducing protection against Salmonella infections . For most experiments, antigens were emulsified in complete Freund adjuvant (CFA); however, the CFA portion of the vaccine was suggested not to be an essential component for the induction of immunity to Salmonella infections, since equivalent levels of protection were obtained when it was omitted from the vaccine . The induction of immunity to murine salmonellosis by prior immunization with CFA-LAP-LPS was demonstrated not to be a transient phenomenon, since C3H/HeJ mice were still protected against lethal S . typhimurium LT2 challenge as late as 225 days postimmunization. Dis Colon Rectum, 1986 Oct, 29(10), 671 - 2 Salmonella typhimurium infection after colectomy with mucosal proctectomy, a pouch, and ileoanal anastomosis; Lontoft E; Severe Salmonella typhimurium infection is described in a patient who was treated previously for ulcerative colitis by total colectomy and mucosal proctectomy with a pouch and ileoanal anastomosis. Protein Eng, 1986 Oct-Nov, 1(1), 59 - 65 The cloning and expression of an anti-peptide antibody: a system for rapid analysis of the binding properties of engineered antibodies; Roberts S et al.; The cloning of the light and heavy chain genes of an antilysozyme monoclonal antibody is described and the application of site-directed mutagenesis for reconstruction of complete cDNAs from incomplete cDNA clones is discussed . The behaviour of the RNA transcripts produced from these cDNAs after their subcloning into an appropriate Salmonella typhimurium, SP6, vector and subsequent injection into Xenopus oocytes has been analysed . The antibody secreted by oocytes after RNA injection has been quantitated and its antigen-binding properties compared with wild-type hybridoma antibody . The results show that this route for expression of antibodies, though limited in its capacity to produce more than a few micrograms of protein, is potentially a means for rapid evaluation of the antigen-binding properties of engineered antibodies. J Immunogenet, 1986 Oct-Dec, 13(5-6), 451 - 7 Genes within the major histocompatibility complex influence the response to ampicillin therapy and severity of relapse in H-2 congenic, susceptible Itys mice infected with virulent Salmonella typhimurium; Maskell DJ et al.; Control by genes within H-2 of natural resistance to fully virulent salmonellae in susceptible mice was studied by the typhoid relapse model . Susceptible (Itys), H-2 congenic C57BL/10 (B10) lines were infected with a lethal dose of the virulent S . typhimurium C5 and rescued from death by ampicillin therapy, inducing a chronic infection . The response to therapy and its cessation, both early and late in the infection, varied in different strains . B10 (H-2b) and B10.D2 (H-2d) responded less well to therapy, and were more prone to relapse on its removal, than B10.A (H-2a) or B10.M (H-2f) mice . This haplotype distribution is the same as that previously reported for H-2 linked resistance and susceptibility of similar mice to salmonellae of low virulence . The results indicate that resistance to a virulent salmonella capable of causing natural infection is influenced by genes within the MHC. Res Commun Chem Pathol Pharmacol, 1986 Oct, 54(1), 101 - 13 The mutagenicity of aflatoxin Q1 to Salmonella typhimurium TA 100 with or without rat or human liver microsomal preparations; Yourtee DM et al.; An investigation of the mutagenicity of aflatoxin Q1 in the Salmonella-mutagenicity test is reported . This mammalian metabolite of aflatoxin B1 was marginally mutagenic to strain TA 98 when either rat or human liver microsomes were present in the test . However, it was mutagenic to TA 100 with the same liver activation sources in the assay . Moreover, it was mutagenic to TA 100 in the absence of liver microsomes . This Q1 mutagenesis, presumably a direct acting base substitution effect, was nearly equal to the liver activated mutagenesis . It was also greater in this respect than aflatoxin B1 or aflatoxicol. Mutat Res, 1986 Oct, 175(2), 47 - 50 Suppressive effects of coffee on the SOS responses induced by UV and chemical mutagens; Obana H et al.; SOS-inducing activity of UV or chemical mutagens (AF-2, 4NQO and MNNG) was strongly suppressed by instant coffee in Salmonella typhimurium TA1535/pSK1002 . As decaffeinated instant coffee showed a similarly strong suppressive effect, it would seem that caffeine, a known inhibitor of SOS responses, is not responsible for the effect observed . The suppression was also shown by freshly brewed coffee extracts . However, the suppression was absent in green coffee-bean extracts . These results suggest that coffee contains some substance(s) which, apart from caffeine, suppresses SOS-inducing activity of UV or chemical mutagens and that the suppressive substance(s) are produced by roasting coffee beans. Carcinogenesis, 1986 Oct, 7(10), 1729 - 32 Inhibition of benzo{a}pyrene-dependent mutagenesis and cytochrome P-450 reductase activity by copper complexes; Reiners JJ Jr et al.; The superoxide dismutase (SOD) biomimetic copper(II) (3,5-diisopropylsalicylate)2 (CuDIPS) has been previously reported to inhibit the tumorigenicity of a polycyclic aromatic hydrocarbon (PAH) requiring metabolic activation . We have used the Ames Salmonella typhimurium revertant assay to survey the effects of CuDIPS and its analogs on the metabolic activation of the PAH benzo{a}pyrene (BP) by liver homogenates . Supplementation of homogenates from normal and Aroclor 1254-treated SENCAR mice with varied concentrations of CuDIPS resulted in a dose-dependent noncompetitive inhibition of BP mutagenesis . Cytochrome P-450 reductase activity in liver homogenates and microsomal preparations was also inhibited by concentrations of CuDIPS possessing antimutagenic activity . Neither DIPS nor ZnDIPS, analogs of CuDIPS lacking SOD activity, inhibited mutagenesis or P-450 reductase activity . CuSO4, which has SOD activity, was almost as effective as CuDIPS on a molar basis in inhibiting mutagenesis and P-450 reductase activity . The inhibitory effects of CuDIPS and CuSO4 could not be attributed to their SOD activity since bovine liver superoxide dismutase, at a 100-fold excess of CuDIPS-SOD activity, had no effect on their activity . Collectively these findings suggest that the in vitro antimutagenic activity of CuDIPS is independent of its salicylate structure and is mediated through a copper-dependent but non SOD-associated inhibition of P-450 reductase activity. J Antimicrob Chemother, 1986 Oct, 18 Suppl C, 183 - 8 Antibiotic resistance profiles and molecular epidemiology of Salmonella typhimurium and S . dublin, mainly from cattle; Jorgensen ST; Among 130 strains of Salmonella typhimurium and 191 strains of S . dublin, all isolated from cattle in the early 1980s, 80% and 63%, respectively, were resistant to one or more (up to three) antibiotics . Monoresistance to sulphonamides was most common . In 169 strains of the two serotypes from 1985 the antibiotic resistance load was of a similar size . The latter batch was not studied with respect to plasmids . In the strains from 1980 and 1981 the plasmid load was analysed by conjugation, transformation, extraction of plasmid DNA and subsequent electrophoresis in agarose gels . Plasmid DNA from 38 strains was further analysed by restriction with endonuclease EcoRI . On the basis of this the strains were classified into four groups: two of S . typhimurium, one of S . dublin and one group of both serotypes . This suggested that dissemination of strains and plasmids mainly occurred through clonal spread of strains. J Hyg (Lond), 1986 Oct, 97(2), 193 - 7 Recognition of the cryptic plasmid, pSLT, by restriction fingerprinting and a study of its incidence in Scottish Salmonella isolates; Brown DJ et al.; The plasmid pSLT is a cryptic plasmid of 60 megadaltons (Md) present in Salmonella typhimurium LT2 . We present evidence that it has a characteristic fingerprint when digested with the restriction enzymes PstI and SmaI . Among a representative collection of S . typhimurium isolates it was present in 67% of strains and was widely distributed amongst different phage types (DT) with the exception of DT10 and U285 . Furthermore, its prevalence among veterinary isolates was significantly higher than among human isolates . It was not found among any of the 96 strains representative of other salmonella serotypes currently prevalent and thus appears to be serotype-specific. Genetics, 1986 Oct, 114(2), 633 - 57 A quantitative model for nonrandom generalized transduction, applied to the phage P22-Salmonella typhimurium system; Mandecki W et al.; A mathematical model for nonrandom generalized transduction is proposed and analyzed . The model takes into account the finite number of transducing particle classes for any given marker . The equations for estimation of the distance between markers from contransduction frequency data are derived and standard errors of the estimates are given . The obtained relationships depend significantly on the number of classes of transducing fragments . The model was applied to estimate the number of transducing fragment classes for a given marker in transduction with phage P22 of Salmonella typhimurium . It was found that the literature data on frequencies of contransduction in crosses with mutual substitution of selective and nonselective markers can be rationalized most accurately by assuming that the mean number of classes is equal to 2 . An improved method for analysis of cotransduction data is proposed on the basis of our model and the results of calculation . The method relies on solving a set of algebraic equations for cotransduction frequencies of markers located within one phage length . The method allows a relatively precise determination of distances between markers, positions of transducing particle ends and deletion or insertion lengths . The approach is applied to the trp-cysB-pyrF and aroC-hisT-purF-dhuA regions of the Salmonella typhimurium chromosome. Chem Biol Interact, 1986 Oct 1, 59(3), 309 - 24 Aerobic and anaerobic reduction of nitrated pyrenes in vitro; Djuric Z et al.; Nitrated pyrenes are mutagenic and tumorigenic environmental pollutants that are activated to DNA-binding derivatives via nitroreduction . We have investigated the enzymatic nitroreduction of 1-nitropyrene, 1,3-, 1,6- and 1,8-dinitropyrene to determine if differences in the extent of nitroreduction may help explain differences in their biological potencies . Each nitrated pyrene was incubated aerobically and anaerobically with 105,000 X g supernatant (S105) from Salmonella typhimurium TA98 and the nitroreductase-deficient strain, TA98NR, and with cytosol and microsomes from rat and human liver . Under anaerobic conditions, 1-nitropyrene and 1,3-dinitropyrene were reduced by TA98 S105 to a lesser extent than 1,6- and 1,8-dinitropyrene . The extent of 1,6- and 1,8-dinitropyrene metabolism was not altered relative to TA98 when using TA98NR S105, but the nitroreduction of 1-nitropyrene and 1,3-dinitropyrene was decreased . Both rat and human liver cytosol and microsomes reduced 1,6- and 1,8-dinitropyrene to greater extents than 1-nitropyrene and 1,3-dinitropyrene . Under aerobic conditions rat and human liver cytosols were similar to TA98 S105 in that aminopyrene decreased while nitrosopyrene formation increased . By comparison, oxygen decreased the microsomal formation of both nitrosopyrenes and aminopyrenes . The reduction of succinoylated cytochrome c was measured during the hepatic metabolism of nitro- and nitrosopyrenes under aerobic conditions . The data indicated that reduced nitro- and nitrosopyrene intermediates were directly reducing succinoylated cytochrome c and that the assay could be used as a measure of aerobic nitroreduction . These studies demonstrate that 1,6- and 1,8-dinitropyrene are reduced to a greater extent than 1-nitropyrene and 1,3-dinitropyrene, which corresponds to their relative biological potencies as mutagens and carcinogens . Furthermore, although more extensive nitroreduction is detected under anaerobic conditions, the nitroreduction that occurs aerobically may be important for the mutagenic and tumorigenic properties of these compounds. J Bacteriol, 1986 Oct, 168(1), 405 - 11 Effects of anaerobic regulatory mutations and catabolite repression on regulation of hydrogen metabolism and hydrogenase isoenzyme composition in Salmonella typhimurium; Jamieson DJ et al.; Hydrogen metabolism in Salmonella typhimurium is differentially regulated by mutations in the two anaerobic regulatory pathways, defined by the fnr (oxrA) and oxrC genes, and is controlled by catabolite repression . The synthesis of the individual hydrogenase isoenzymes is also specifically influenced by fnr and oxrC mutations and by catabolite repression in a manner entirely consistent with the proposed role for each isoenzyme in hydrogen metabolism . Synthesis of hydrogenase isoenzyme 2 was found to be fnr dependent and oxrC independent, consistent with a role in respiration-linked hydrogen uptake which was shown to be similarly regulated . Also in keeping with such a respiratory role was the finding that both hydrogen uptake and the expression of isoenzyme 2 are under catabolite repression . In contrast, formate hydrogenlyase-dependent hydrogen evolution, characteristic of fermentative growth, was reduced in oxrC strains but not in fnr strains . Hydrogenase 3 activity was similarly regulated, consistent with a role in hydrogen evolution . Unlike the expression of hydrogenases 2 and 3, hydrogenase 1 expression was both fnr and oxrC dependent . Hydrogen uptake during fermentative growth was also both fnr and oxrC dependent . This provided good evidence for a distinction between hydrogen uptake during fermentation- and respiration-dependent growth and for a hydrogen-recycling process . The pattern of anaerobic control of hydrogenase activities illustrated the functional diversity of the isoenzymes and, in addition, the physiological distinction between the two anaerobic regulatory pathways, anaerobic respiratory genes being fnr dependent and enzymes required during fermentative growth being oxrC dependent. Zh Mikrobiol Epidemiol Immunobiol, 1986 Oct, (10), 3 - 8 {Isolation and characteristics of the biological and genetic properties of neamin-resistant mutants of Salmonella typhimurium and Salmonella dublin candidates for vaccine creation}; Marakusha BI et al.; Mutants, resistant to neamine and spectinomycin, have been isolated from S . typhimurium and S . dublin highly virulent strains . The neamine-resistant mutants can be divided into 3 classes in accordance with their sensitivity to streptomycin: sensitive, resistant to low and high concentrations of this antibiotic . The transduction analysis with the use of bacteriophage P 22 has revealed that the spectinomycin-resistant mutations under study are spc A mutations, while the mutations leading to resistance to neamine in class Near Strr 500 are nea B mutations . The mutation leading to resistance to spectinomycin (spc A) has been found to produce no changes in the virulence of salmonellae in the intraperitoneal infection of mice . The mutations leading to resistance to neamine and streptomycin (nea B and str A) have been found to decrease virulence. Microb Pathog, 1986 Oct, 1(5), 433 - 41 Evidence for the importance of O antigen specific antibodies in mouse-protective Salmonella outer membrane protein (porin) antisera; Saxen H et al.; The antibodies responsible for the protective effect of sera obtained by immunizing rabbits with the major outer membrane protein porin of Salmonella typhimurium complexed with LPS (Kuusi et al., Infect . Immun., 1981; 34:328-332) were found to be directed to the O antigen . They were effective in very small concentration which probably accounted for our failure to identify them before or now by in vitro methods . Although both the porin and the LPS in the complexes used for immunization were isolated from rough (R) form organisms devoid of O antigen by all usually applied criteria, the antigen contained a small amount of smooth form LPS, most probably derived from a slight leakiness of the rfa mutation responsible for the R character . The small amount of contaminating O antigen was apparently rendered highly immunogenic by complexation with the outer membrane protein. Toxicol Appl Pharmacol, 1986 Sep 30, 85(3), 355 - 66 Microsomal activation of fluoranthene to mutagenic metabolites; Babson JR et al.; The in vitro metabolism of fluoranthene (FA) was assessed by incubating 3-{3H}FA, the synthesis of which is described, with rat hepatic microsomal enzymes . Several metabolites including the FA 2,3-diol, FA 2-3,-quinone, 3-OH-FA, 1-OH-FA, and 8-OH-FA were isolated by high-pressure liquid chromatography and identified by comparison of chromatographic properties and uv-visible spectra with those of synthetic standards . The major metabolite produced over the FA concentration range studied (23-233 microM) was FA 2,3-diol, accounting for 29-43% of the total extractable metabolites . This diol was characterized further by high-resolution mass spectroscopy and H-NMR and determined to be identical in structure to the trans-2,3-dihydroxy-2,3-dihydrofluoranthene . The FA 2,3-diol, syn and anti 2,3-diol-1,10b-epoxides, FA 2,3-quinone, and FA 7,8-diol were all shown to be mutagenic toward Salmonella typhimurium TM677 . The FA 1,10b-diol and syn and anti FA 1,10b-diol-2,3-epoxides were not mutagenic . The epoxide hydrolase inhibitor, 3,3,3-trichloropropylene oxide, markedly reduced the mutagenic potency of FA while concurrently inhibiting FA 2,3-diol production but not overall FA metabolism . These results suggests that a major metabolic activation pathway of FA resulting in the production of mutagenic species involves the formation of the FA 2,3-diol and the subsequent oxidation of this diol to a FA 2,3-diol-1,10b-epoxide . Another minor activation pathway with mutagenic endpoints may involve the formation of the 7,8-diol. J Mol Biol, 1986 Sep 5, 191(1), 39 - 58 Novel regulatory mutants of the phosphate regulon in Escherichia coli K-12; Wanner BL; New pleiotropic mutants were isolated that express either the phoA, psiE or psiO promoter constitutively and simultaneously alter bacterial alkaline phosphatase regulation, carbon utilization or ultraviolet light sensitivity . To do this, Lac+ mutants were isolated from strains with the appropriate lacZ transcriptional fusions . Over 300 independent mutants were characterized, and all that constitutively express phoA map in phoR, phoU, the phosphate-specific transport system or a new locus called phoF . However, only phoU mutants express both phoA and psiE constitutively . Carbohydrate-utilizing mutants that show constitutive expression of psiE and psiO map in cya, crp and, possibly, crr . Also, numerous ultraviolet-light-sensitive mutants were discovered that show increased psiO expression and map in lon . Some other mutations that lead to constitutive psiO expression (which is normally induced either by phosphate, nitrogen or carbon starvation or anoxia) show decreased expression of phoA . Also, several mutants were found that show an unusual metastable character affecting psiO or phoA transcription . In these, colonies spontaneously switch between an induced and repressed "state" with respect to lac or bacterial alkaline phosphatase expression . In some, the clonal variation of the lactose phenotype or bacterial alkaline phosphatase synthesis is recA-independent and phenotypically resembles phase variation in Salmonella typhimurium . The latter class are called "phase mutants" . The mutants are discussed in terms of protein-nucleic acid interactions and/or possible changes in the DNA, i.e . modifications or rearrangements, within the phosphate gene system, that are physiologically regulated. Carcinogenesis, 1986 Sep, 7(9), 1561 - 7 Modulation of cytotoxic and genotoxic effects of 2-acetylaminofluorene in rat and hamster hepatocytes by 3-methylcholanthrene pre-treatment; Holme JA et al.; It is well known that 2-acetylaminofluorene (AAF)-induced liver cancer is reduced by simultaneous administration of 3-methylcholanthrene (MC) in the rat, but not in the hamster . The present report examines the effects of MC pre-treatment on the metabolism and toxicity of AAF in monolayer cultures of hepatocytes . Hepatocytes isolated from pre-treated animals of both species metabolized AAF and 2-aminofluorene (AF) to metabolites mutagenic to Salmonella typhimurium more efficiently than hepatocytes from control animals . MC-pre-treated rat hepatocytes showed increased responses to AAF- and AF-induced unscheduled DNA synthesis, while MC-pre-treated hamster hepatocytes were less responsive than the untreated hepatocytes . Increased cytotoxic effects of AAF were observed in MC-pre-treated rat hepatocytes, whereas AAF was not cytotoxic in hamster hepatocytes from either pre-treated or control animals . MC pre-treatment caused increased rates of formation of C-hydroxylated, N-hydroxylated, water-soluble and covalently macromolecular bound AAF metabolites in both species . No significant effect of MC pre-treatment was seen on the formation of AF from AAF . A large decrease in the ratio between covalently macromolecular bound (activated) metabolites and the sum of C-hydroxylated and water-soluble (detoxified) AAF metabolites, was seen after MC pre-treatment of rat hepatocytes, whereas no or only a minor decrease was observed in hamster hepatocytes . This ratio correlated much better with the in vivo carcinogenicity data than the other parameters such as mutagenicity, DNA repair or covalent macromolecular binding . Thus, the hypothesis that AAF-induced liver cancer depends less on the rate at which AAF is activated, but more on the relative proportion of the dose which is activated, is supported by the present data. J Nat Prod, 1986 Sep-Oct, 49(5), 866 - 71 Mutagenic perylenequinone metabolites of Alternaria alternata: altertoxins I, II, and III; Stack ME et al.; The mold genus Alternaria is a widely distributed plant pathogen . Some of these species, e.g., A . alternata, are common decay organisms of fruits and vegetables . Two novel perylene oxide metabolites, altertoxins II and III, have been identified in extracts of A . alternata isolates that exhibit mutagenic responses in the Ames Salmonella typhimurium assay . These identifications were based on mass, optical rotational, and 1H- and 13C-nmr spectral studies . Previous reports of related perylene dione mycotoxins have been clarified. Food Chem Toxicol, 1986 Sep, 24(9), 987 - 8 Salmonella/microsome mutagenicity tests of heat-processed milk samples; Sekizawa J et al.; Samples of whole milk were heat treated by commercial heat-sterilization, by commercial heat-pasteurization or by a laboratory heat-pasteurization (65 degrees C for 30 min) . Each sample was tested for mutagenicity in Salmonella typhimurium strains TA98 and TA100 with and without S-9 mix . Dichloromethane extracts of milk heated at 100, 135 and 150 degrees C for 5 hr were also tested for mutagenicity using the same assay . None of these samples exhibited mutagenicity in the Ames assay used. Bioorg Khim, 1986 Sep, 12(9), 1181 - 4 {Sensitivity of mannosyl transferases from Salmonella serotype E1 and B to modification of the donor heterocyclic base}; Druzhinina TN et al.; A series of synthetic nucleoside diphosphate mannoses with different heterocyclic bases were tested as GDP-Man analogues in enzymatic mannosylation during assembly of O-antigen repeating units of Salmonella anatum and Salmonella typhimurium . The substrate efficiency was found to depend strongly on oxygen atom presence at C6 of the purine residue, the H2N-C2-N1-H grouping of the heterocyclic nucleus being less important . UDP-Man proved to be an efficient substrate for the mannosylation reactions. Genetika, 1986 Sep, 22(9), 2265 - 71 {Study of promutagen biotransformation in the Ames test . IV . The effect of transplanted tumors on the biotransformation of various antineoplastic agents}; Oblapenko NG et al.; The effect of transplantation of rat tumours Jensen sarcoma, sarcoma 45, sarcoma M-1, as well as of inoculation of rat normal connective tissue on the processes of biotransformation of antitumour preparations cyclophosphane (CP), thiophosphamide, prospidine and of model compound nitrosomorpholine (NM) was studied . The study was accomplished by means of the Ames test with indicator bacterial strain Salmonella typhimurium TA 1950 in relation to the reactions of the 1st and the 2nd phases of xenobiotics metabolism . It was shown that the presence of tumours leads to inhibition of both metabolic activation processes of the promutagens NM and CP and the conjugation reactions of genetically active metabolites of these compounds with reduced glutathione . Genetic danger is supposed to be increased during application of antitumour preparations, the mutagenic activity of which is due to the activity of their metabolites . It is noted that the most essential effect on biotransformation processes of NM and CP was exhibited by sarcoma M-1, the most important changes of the biotransformation processes of promutagens being observed in the initial period of pathologic process, i.e . on the 3rd day after inoculation . Transplantation of the normal connective tissue of rats had no effect on reactions of both the 1st and the 2nd phase of metabolism of the promutagens studied. Genetika, 1986 Sep, 22(9), 2259 - 64 {Study of promutagen biotransformation in the Ames test . III . The role of conjugation with glucuronic acid and sulfate in the modification of mutagenic effect of nitrosomorpholine, diethylnitrosamine and cyclophosphamide}; Loknitskaia NN et al.; The role of reactions of conjugation with uridine diphosphoglucuronic acid (UDPGA) and with 3-phosphoadenosine-5-phosphosulfate (PAPS) in modification of the mutagenic effect of diethyl nitrosamine (DENA), nitrosomorpholine (NM) and cyclophosphane (CP) was studied by the Ames test . It was shown that adding UDPGA to the activating mixture significantly decreased the level of the mutagenic effect of DENA, NM and CP on bacteria Salmonella typhimurium TA 1950, when S9 and microsomal fractions of rat liver homogenate were used . Adding PAPS to the activating mixture when S9 and cytosole fractions were used, did not affect mutagenic action of DENA on S . typhimurium TA 1950 and TA 1535, enhancing the mutagenic effect of CP on TA 1535, with no such influence on TA 1950 . Introduction of PAPS into the activating mixture elevated the mutagenic effect of NM on both bacterial strains using S9 fraction but not cytosole fraction. Mutat Res, 1986 Sep, 168(2), 69 - 240 The Salmonella typhimurium/mammalian microsomal assay . A report of the U.S . Environmental Protection Agency Gene-Tox Program; Kier LD et al.; The Salmonella assay has been in use for almost 15 years and can be defined as a routine test for mutagenicity and for predicting potential carcinogenicity . It detects the majority of animal carcinogens and consequently plays an important role in safety assessment . The test is also routinely used as the frontline screen for environmental samples (complex mixtures) isolated from air, water and food . This role will continue to remain an area of growth as or because sample volumes associated with these testing areas are generally very limited and more extensive testing is generally impossible . While this test, like all others, has some limitations, it is recommended that it be regularly included in all genetic testing batteries. J Med Microbiol, 1986 Sep, 22(2), 119 - 23 Spontaneous deletions of drug-resistance determinants from Salmonella typhimurium in Escherichia coli; Roy S et al.; Plasmids isolated from two different clinical isolates of Salmonella typhimurium, both resistant to the antibiotics ampicillin, tetracycline, streptomycin and chloramphenicol, were used to transform Escherichia coli . Segregation of antibiotic-resistance determinants occurred in both cases . Analysis of plasmids from one set of segregants by DNA-DNA hybridisation indicated that the segregation was due to precise deletions in the transforming plasmid. Cancer Res, 1986 Sep, 46(9), 4556 - 65 Mutagenic and cell-transforming activities of triol-epoxides as compared to other chrysene metabolites; Glatt H et al.; The syn- and anti-isomers of the bay-region diol-epoxides of chrysene and of 3-hydroxychrysene and their metabolic precursors have been investigated for mutagenicity in Salmonella typhimurium (reversion to histidine prototrophy) and V79 Chinese hamster cells (acquirement of resistance to 6-thioguanine) and for transforming activity in M2 mouse prostate cells . Other known and potential chrysene metabolites have been included in mutagenicity experiments . Direct mutagenic activity in S . typhimurium TA 100 exhibited, in order of potency, anti-triol-epoxide greater than syn-triol-epoxide greater than anti-diol-epoxide greater than syn-diol-epoxide greater than chrysene 5,6-oxide much greater than chrysene-1,2-quinone, chrysene-3,4-quinone, and chrysene 5,6-quinone . Chrysene, the six isomeric chrysenols, and the trans-dihydrodiols {trans-1,2-dihydroxy-1,2-dihydrochrysene (chrysene-1,2-diol), trans-3,4-dihydroxy-3,4-dihydrochrysene, trans-5,6-dihydroxy-5,6-dihydrochrysene, and 9-hydroxy-trans-1,2-dihydroxy-1,2-dihydrochrysene (9-hydroxychrysene-1,2-diol)} were inactive per se but were activated to mutagens in the presence of reduced nicotinamide adenine dinucleotide phosphate-fortified postmitochondrial fraction (S9 mix) of liver homogenate from Arochlor 1254-treated rats . Chrysene, 3-hydroxychrysene, chrysene-1,2-diol, and 9-hydroxychrysene-1,2-diol were activated efficiently; the other compounds were activated weakly . In S . typhimurium TA 98, the mutagenic activities of the chrysene derivatives were weak in comparison with those in the strain TA 100 . trans-3,4-Dihydroxy-3,4-dihydrochrysene (in the presence of S9 mix) was the most efficacious mutagen in strain TA 98 . The relative mutagenic potencies of the directly active compounds differed from the results obtained in strain TA 100, in that in strain TA 98 the anti-diol-epoxide was more mutagenic than the triol-epoxides and chrysene 5,6-oxide was more mutagenic than syn-diol-epoxide and syn-triol-epoxide . In V79 cells, the order of mutagenic potency was: anti-triol-epoxide greater than anti-diol-epoxide greater than syn-triol-epoxide greater than syn-diol-epoxide greater than chyrsene 5,6-oxide greater than chrysene-1,2-diol (in the presence of S9 mix) greater than 9-hydroxychrysene-1,2-diol (in the presence of S9 mix) greater trans-3,4-dihydroxy-3,4-dihydrochrysene in the presence of S9 mix) . Chrysene, 3-hydroxychrysene, 5-hydroxychrysene, and 6-hydroxychrysene showed no mutagenic effects in V79 cells, either in the presence or absence of S9 mix.(ABSTRACT TRUNCATED AT 400 WORDS) Cell Biol Toxicol, 1986 Sep, 2(3), 341 - 55 Formation of reactive 1-nitropyrene metabolites by lung microsomes and isolated lung cells; Dybing E et al.; The metabolism and activation of 1-nitropyrene (1-NP) to reactive intermediates by lung microsomes and isolated lung cells was studied . Mutagenicity of 1-NP metabolites was assayed in Salmonella typhimurium TA98NR, a strain lacking a major component of nitroreductase activity . In the presence of NADPH, microsomes from rabbit, rat and hamster lung metabolized 1-NP to mutagenic products to a similar degree . Pretreatment with a mixture of polychlorinated biphenyls (PCB) decreased the formation of mutagenic metabolites by rabbit lung microsomes, but did not affect the production of mutagens by rat or hamster lung microsomes . 3H-1-NP was metabolized to covalently bound protein products at a rate of 82 and 10 pmol/mg by rabbit and hamster lung microsomes, respectively, whereas no binding was detected in rat lung microsomes . PCB-pretreatment increased covalent protein binding of 3H-1-NP in lung microsomes from hamster and rat, but decreased the binding in rabbit lung microsomes . High performance liquid chromatography analysis indicated that 3H-1-NP was readily converted to ring-hydroxylated products by rabbit and hamster lung microsomes; the rate was much lower with rat lung microsomes . 3H-1-NP was activated to metabolites that covalently bound to protein in isolated rabbit lung cells, with the following rates being observed: Clara cells greater than lung digest greater than type II cells . In contrast, covalent protein binding in cells isolated from rat lung was very low . 1-NP was not activated to products mutagenic for S . typhimurium TA 98NR when co-incubated with cells isolated either from rabbit or rat lung. Rev Infect Dis, 1986 Sep-Oct, 8(5), 682 - 92 Molecular epidemiology of bacterial infections: examples of methodology and of investigations of outbreaks; Wachsmuth K; Plasmid profile analysis, plasmid and chromosomal bacterial restriction endonuclease DNA analysis, and DNA hybridization are increasingly used in clinical microbiology and epidemiology . These techniques have been applied, singly and in combination, to investigations of outbreaks, including those of diarrheal diseases caused by pandemic Vibrio cholerae, enterotoxigenic and enterohemorrhagic Escherichia coli, Salmonella muenchen, and Salmonella typhimurium . The techniques have been critical in the unraveling of outbreaks of disease caused by nosocomial and community-acquired pathogens . Although there are limitations to these methods, their applications have important ramifications for basic science and public health. Cancer Lett, 1986 Sep, 32(3), 327 - 34 Use of the human liver cell line Hep G2 in a modified Salmonella reversion assay; Zhuo Z et al.; The human hepatoma cell line Hep G2 was used to activate promutagenic chemicals to mutagens in a modified Salmonella typhimurium reversion assay . Hep G2 cells mediated positive mutagenic responses in tester strain TA98 with 5 and 25 micrograms/plate of 2-aminofluorene, but these responses were consistently lower than those seen using primary rat hepatocytes . In addition, 3 and 6 X 10(6) Hep G2 cells per assay produced positive mutagenic responses with 2-aminoanthracene, benzidine, acetylbenzidine and aflatoxin B1, while benzo{a}pyrene, 7,12-dimethylbenz{a}anthracene, 3-methylcholanthrene, 4-aminobiphenyl and 4- and 11-aminobenzo{a}pyrene were nonmutagenic with Hep G2-cell activation . These results indicate that Hep G2 cells may be a useful intact cellular metabolizing system of human origin for predicting the genotoxicity of promutagenic agents, but that the use of Salmonella as a target cell may limit the classes of mutagens detected. Proc Natl Acad Sci U S A, 1986 Sep, 83(18), 6805 - 9 Anaerobic regulation of nitrogen-fixation genes in Rhodopseudomonas capsulata; Kranz RG et al.; A Rhodopseudomonas capsulata nifH::lacZ gene fusion was used to isolate constitutive mutants of R . capsulata, unable to repress nif gene transcription anaerobically with every fixed-nitrogen source tested . When these nifc strains were grown aerobically, nif gene transcription was repressed . These results indicate that the regulation of nif gene transcription by fixed nitrogen is different from the regulation by oxygen . Under anaerobic conditions, nif gene transcription in both R . capsulata and Klebsiella pneumoniae is specifically prevented by inhibitors of DNA gyrase {DNA topoisomerase type II (ATP-hydrolyzing), EC 5.99.1.3} . A recent study has shown that anaerobically grown Salmonella typhimurium have high DNA gyrase activity, whereas aerobically grown cells have high DNA topoisomerase type I (EC 5.99.1.2) activity and DNA that is more relaxed {Yamamoto, N . & Droffner, M . L . (1985) Proc . Natl . Acad . Sci . USA 82, 2077-2081} . In view of these results, we suggest that the control of nif gene transcription in response to oxygen is determined by the action of DNA gyrase and DNA topoisomerase I . Thus, although nitrogen control of nif gene expression requires the products of regulatory genes for which constitutive mutations can be isolated, oxygen appears instead to prevent the adoption of a DNA conformation necessary, directly or indirectly, for nif gene transcription. J Bacteriol, 1986 Sep, 167(3), 1086 - 8 Genetics of NAD metabolism in Salmonella typhimurium and cloning of the nadA and pnuC loci; Tirgari S et al.; The nadA and pnuC loci of S . typhimurium were cloned and found to reside within a 2.2-kilobase region . Two-dimensional O'Farrell gel electrophoresis of the proteins produced after chloramphenicol amplification and subsequent release from chloramphenicol inhibition revealed NadA and PnuC to be 43,000- and 25,000-molecular-weight proteins, respectively . The data indicated that nadA and pnuC represent two distinct genes. Food Chem Toxicol, 1986 Sep, 24(9), 981 - 5 Mutagenicity studies of selected antihistamines, their metabolites and products of nitrosation; Kammerer RC et al.; Methapyrilene, four structurally related antihistamines, three metabolites of methapyrilene and two products of the reaction of methapyrilene with nitrite were all tested for mutagenicity to Salmonella typhimurium . The two products of the methapyrilene-nitrite reaction have also been identified as metabolites of methapyrilene . None was mutagenic alone, either with or without rat liver S-9 activation . After reaction with sodium nitrite in acetic acid solution (nitrosation), the products of five of the ten compounds were mutagenic . These compounds were methaphenilene, 2-thiophenemethanol, 2-thiophenecarboxylic acid, N-(2-pyridyl)-N'N'-dimethylethylenediamine and N-(2-thenylmethyl)-2-aminopyridine. J Bacteriol, 1986 Sep, 167(3), 1081 - 2 Exclusion of high-molecular-weight maltosaccharides by lipopolysaccharide O-antigen of Escherichia coli and Salmonella typhimurium; Ferenci T et al.; The barrier properties of lipopolysaccharide were studied by testing the influence of O-antigen on the binding of ligand to maltoporin in the outer membranes of Escherichia coli and Salmonella typhimurium . Maltoporin (LamB protein) of Escherichia coli K-12 was capable of interacting with macromolecular starch polysaccharides, as was previously shown by the binding of intact bacteria to fluorescein-labeled amylopectin or to starch-Sepharose columns . In contrast, strains with complete O-antigenic lipopolysaccharide showed reduced binding to these substrates . A similar result was obtained with Salmonella typhimurium LT2, which did not bind to starch unless rfa mutations removed noncore polysaccharide . The exclusion limit of the lipopolysaccharide permeability barrier to alpha-glucans was tested by measuring the maltoporin-dependent transport of maltose and its inhibition by maltodextrins of various sizes . Only amylopectin (molecular weight, greater than 25,000) was excluded in transport experiments, whereas maltodextrins with molecular weights of up to 2,000 were not excluded by the presence of an O-polysaccharide layer. Vet Rec, 1986 Aug 30, 119(9), 201 - 3 Salmonella in sewage effluent and the relationship to animal and human disease in the north of Scotland; Johnston WS et al.; During the period July 1982 to December 1984, the presence of salmonella organisms was investigated at weekly intervals in the sewage system and abattoir effluent of a town in the north of Scotland . Three hundred and fifteen isolations, representing 37 different serotypes, were made which included 20 different Salmonella typhimurium phage types and four different S enteritidis phage types . Ten of the serotypes were isolated from livestock in the district during the survey as well as in the periods immediately before and after the survey . There were seven recorded incidents of human infection, involving four salmonella serotypes, only three of which were isolated concurrently from sewage. Biochemistry, 1986 Aug 26, 25(17), 4778 - 84 A cysteine residue (cysteine-116) in the histidinol binding site of histidinol dehydrogenase; Grubmeyer CT et al.; Salmonella typhimurium L-histidinol dehydrogenase (EC 1.1.1.23), a four-electron dehydrogenase, was inactivated by an active-site-directed modification reagent, 7-chloro-4-nitro-2,1,3-benzoxadiazole (NBD-Cl) . The inactivation followed pseudo-first-order kinetics and was prevented by low concentrations of the substrate L-histidinol or by the competitive inhibitors histamine and imidazole . The observed rate saturation kinetics for inactivation suggest that NBD-Cl binds to the enzyme noncovalently before covalent inactivation occurs . The UV spectrum of the inactivated enzyme showed a peak at 420 nm, indicative of sulfhydryl modification . Stoichiometry experiments indicated that full inactivation was correlated with modification of 1.5 sulfhydryl groups per subunit of enzyme . By use of a substrate protection scheme, it was shown that 0.5 sulfhydryl per enzyme subunit was neither protected against NBD-Cl modification by L-histidinol nor essential for activity . Modification of the additional 1.0 sulfhydryl caused complete loss of enzyme activity and was prevented by L-histidinol . Pepsin digestion of NBD-modified enzyme was used to prepare labeled peptides under conditions that prevented migration of the NBD group . HPLC purification of the peptides was monitored at 420 nm, which is highly selective for NBD-labeled cysteine residues . By amino acid sequencing of the major peptides, it was shown that the reagent modified primarily Cys-116 and Cys-377 and that the presence of L-histidinol gave significant protection of Cys-116 . The presence of a cysteine residue in the histidinol binding site is consistent with models in which formation and subsequent oxidation of a thiohemiacetal occurs as an intermediate step in the overall reaction. J Biol Chem, 1986 Aug 15, 261(23), 10814 - 20 Kinetics of receptor modification . The multiply methylated aspartate receptors involved in bacterial chemotaxis; Terwilliger TC et al.; A method for determining the extent of methyl esterification of each of the four potential sites on the aspartate receptors involved in chemotaxis in Escherichia coli and Salmonella typhimurium is presented . In this procedure, radioactive methyl esters are incorporated into the receptors, the receptors are cleaved by trypsin and the V8 protease from Staphylococcus aureus, and the four fragments containing sites of methylation are separated by high performance liquid chromatography . Using this technique, we find that the rate of methyl esterification increases at all four sites after stimulation with the "attractant" aspartate, suggesting that all four sites of modification are involved in adaptation to aspartate . We also find that the rate of methyl esterification at each site is correlated with the homology between the protein sequence at that site and the "consensus" sequence, Glu-Glu-X-X-Ala-Thr/Ser. J Toxicol Sci, 1986 Aug, 11(3), 197 - 211 {Toxicological studies on sophorolipid derivatives . (I) . Acute toxicity, eye irritation, primary skin irritation, skin sensitization, phototoxicity, photosensitization, mutagenicity of polyoxypropylene (12) {(2'-0-beta-D-glucopyranosyl-beta-D-glucopyranosyl)oxy-} fatty acid ester-}; Ikeda Y et al.; Acute toxicity, eye irritation, primary skin irritation, skin sensitization, phototoxicity, photosensitization and mutagenicity of sophorolipid derivatives were studied in rats, mice, rabbits, guinea pigs and Salmonella typhimurium strains . The acute oral toxicity of sophorolipid (SL) which Torulopsis bombicola produces, and its derivatives (PSL, Ethyl-SL and Oleyl-SL) were shown to be very low . The LD50 values of PSL ranged from 10 g/kg to 16 g/kg on oral administration in rats and mice, and from 5.8 g/kg to 6.6 g/kg on subcutaneous administration in mice . The oral LD50 values of Ethyl-SL and Oleyl-SL were estimated to be greater than 15 g/kg and that of SL was 12.5 g/kg . In eye irritation study, PSL failed to produce any reactions at 50% concentration even when the rabbit eye was not subsequently washed . SL, Ethyl-SL, Oleyl-SL and Tween 20 were "no irritant" or "slight irritant" to the rabbit eye at 20% concentration . PSL showed no irritancy to both the intact and abraded guinea pig skin at 50% concentration . And in other examinations, it was also indicated that PSL had no potentials of skin sensitization, phototoxicity and photosensitization in guinea pigs and had no potentials of mutagenicity in Salmonella typhimurium TA98 and TA100. Environ Health Perspect, 1986 Aug, 67, 89 - 91 Mutagens in coffee and other beverages; Nagao M et al.; A cup of coffee contains mutagens which produce about 5 X 10(4)-10(5) revertants of Salmonella typhimurium TA 100 without S9 mix . One of the mutagens was identified to be methylglyoxal . Methylglyoxal was present in various beverages such as black tea, whisky, and brandy . Methylglyoxal itself induced tumors in rats when administered by subcutaneous injection . However, the mutagenic properties of coffee were different from those of methylglyoxal . The mutagenicity of coffee was suppressed by catalase, and coffee was found to contain hydrogen peroxide . Furthermore, coffee solution was found to have a hydrogen peroxide-generating system . Instant coffee (15 mg/mL) contains 130 microM hydrogen peroxide immediately after the dissolution of coffee powder in water at room temperature . The concentration of hydrogen peroxide increased with time . The mutagenicity of methylglyoxal was increased by the copresence of hydrogen peroxide . A maximum of 30-fold enhancement was observed . The mutagenicity of black tea but not that of whisky was suppressed by catalase. Environ Health Perspect, 1986 Aug, 67, 121 - 7 Genotoxicity, carcinogenicity, and mode of action of the fried food mutagen 2-amino-3-methylimidazo{4,5-f}quinoline (IQ); Weisburger JH et al.; Because mutagens typified by 2-amino-3-methylimidazo{4,5-f}quinoline (IQ) observed in cooked foods are widely consumed, detailed studies of their biochemical and biological properties including carcinogenicity are most important . IQ induces unscheduled DNA synthesis in liver cells, which when taken together with its powerful mutagenicity in the Salmonella typhimurium test system, predicts carcinogenicity . In female Sprague-Dawley rats, IQ did exhibit potent carcinogenicity for the mammary gland, the ear duct, and to a lesser extent, pancreas and bladder . Data from Japanese laboratories indicate carcinogenicity also to the intestinal tract . Thus, one of the mutagens formed during cooking is a versatile carcinogen that because of extensive human intake requires urgent exploration for specific human cancer risk. Environ Health Perspect, 1986 Aug, 67, 111 - 6 Hydroxylation of guanine in nucleosides and DNA at the C-8 position by heated glucose and oxygen radical-forming agents; Kasai H et al.; Heated glucose is mutagenic to Salmonella typhimurium TA 100 in the absence of S-9 mix . For identifying unknown mutagens in heated glucose (dry solid, 200 degrees C, 20 min), reaction with isopropylideneguanosine (IPG) was followed by isolation and characterization of the mutagen-IPG adduct . Two adducts, glyoxal-IPG and 8-hydroxy-IPG, were identified in the reaction mixture by this technique . To elucidate the mechanism of this hydroxylation reaction, we investigated the abilities of various agents to hydroxylate deoxyguanosine or guanine base in DNA . Various reducing agents, metals, asbestoses, polyphenols, aminophenols, and X-ray were effective for hydroxylation, and an oxygen radical seems to be the reactive species . For sensitive detection of 8-hydroxyguanine, a monoclonal antibody for it was prepared. Br J Dermatol, 1986 Aug, 115 Suppl 31, 86 - 92 Cutaneous phototoxicity reactions; Lowe NJ; This paper reviews some potential mechanisms of cutaneous phototoxicity and discusses selected methods of predicting and ranking phototoxic reactions . Phototoxicity is a non-immunological reaction that is induced by the action of light on a photoactive chemical . The phototoxic chemical may be either exogenous or endogenous, and if exogenous may include topical or systemic agents . Examples of phototoxic agents include psoralens (e.g . 5-methoxypsoralen, 8-methoxypsoralen, as well as the isopsoralens) . Psoralens are used therapeutically for the treatment of different skin diseases and psoralen-like chemicals may be present in perfumes and cosmetics . Phototoxic reactions can be evaluated visually in animals . The hairless mouse has also proved useful with skin thickening as a marker of dermal oedema and the induction of polyamine biosynthetic enzymes, as well as other biochemical changes being indicative of cutaneous phototoxicity . In vitro tests of phototoxicity include the Candida albicans assay as well as bacterial mutagenicity . For example, in the latter category different psoralens vary in their ability to induce mutagenicity in Salmonella typhimurium strains, an assay which can provide rapid screening of potential phototoxicity of chemicals . For human testing, phototoxic chemicals can be delivered topically or orally, and in conjunction with appropriate ultraviolet radiation will produce phototoxic reactions which can be evaluated for intensity of response. Environ Res, 1986 Aug, 40(2), 427 - 36 Bioavailability of 1-nitropyrene from model coal fly ash and its uptake by alveolar macrophages; Mumford JL et al.; Alveolar macrophage cultures exposed to coal fly ash vapor-coated with 1-nitropyrene were used as a model system to study the bioavailability and the uptake of a nitroaromatic hydrocarbon from coal combustion emissions . Initially, 1-nitropyrene-coated fly ash and uncoated fly ash were examined for cytotoxicity using rabbit alveolar macrophages and for mutagenicity in the Salmonella typhimurium plate incorporation assay . The results were compared to determine the effects of vapor deposition . The distribution and recovery of 1-nitropyrene from macrophage cultures treated with coated fly ash were determined by using a reverse-phase high-performance liquid chromatography-fluorescence method . 1-Nitropyrene alone was not very toxic, nor did vapor deposition of 1-nitropyrene onto coal fly ash significantly affect the toxicity of the fly ash . Most toxicity resulted from the original, uncoated fly ash particles . 1-Nitropyrene after being coated onto the particles was bioavailable in agar and aqueous culture medium . The coated fly ash showed mutagenic activity when the particles were tested directly; the uncoated fly ash did not show mutagenic activity . 1-Nitropyrene recovery from alveolar macrophage cultures exposed to the coated fly ash diminished as cell number increased . The rate of 1-nitropyrene loss was 2.7 ng/10(6) macrophages for medium and 4.1 ng/10(6) macrophages for the whole culture . The mutagenic activity recovered from these macrophage cultures also decreased with increasing cell number. J Gen Microbiol, 1986 Aug, 132 ( Pt 8), 2079 - 85 The traT protein is able to normalize the phenotype of a plasmid-carried permeability mutation of Salmonella typhimurium; Sukupolvi S et al.; The isolation of different classes of antibiotic-supersensitive outer membrane permeability mutants of Salmonella typhimurium has been described previously (Sukupolvi et al., 1984, Journal of Bacteriology 159, 704-712) . One of these, the SS-A mutation, sensitizes the bacteria to gentian violet and to hydrophobic antibiotics . The phenotype of the SS-A mutant was restored to normal when a cloned fragment of the F plasmid, or the R plasmid R6-5, carrying the genes traS, T and D was introduced on a multicopy plasmid . The introduction of a plasmid carrying only the traT gene showed that this gene was sufficient to restore the phenotype . Only clones with functioning traT (irrespective of copy number) restored the normal antibiotic-resistant phenotype in the SS-A mutant . An incompatibility test using a donor strain which carried transposon Tn10 in the 60 MDa plasmid of S . typhimurium and a recipient in which Tn5 was placed close to the SS-A mutation indicated that the SS-A mutation was located in the 60 MDa virulence plasmid (previously called the cryptic plasmid) of S . typhimurium . The introduction of the large virulence plasmid carrying the SS-A mutant allele into wild-type S . typhimurium or Escherichia coli resulted in strains with a phenotype identical to that of the original SS-A mutant. Mol Gen Genet, 1986 Aug, 204(2), 281 - 4 Lowered induction of genetic tandem duplications in Salmonella by the pKM101 plasmid; Pall ML et al.; Selection for 3-amino-1,2,4-triazole (AT) resistance in certain strains of Salmonella typhimurium has been previously shown to select for genetic tandem duplications of the histidine operon . We show here that agents which induce tandem duplications are less effective in such induction in the presence of the pKM101 plasmid . The presence of the plasmid also produces an increase in AT-resistance due to mechanisms other than duplication, presumably because pKM101 produces high levels of error-prone repair . We suggest that high levels of error-prone repair may cause decreases in tandem duplication induction and propose that error-prone repair and tandem duplication may be alternative cellular responses to certain DNA lesions. J Environ Sci Health B, 1986 Aug, 21(4), 319 - 34 Screening pesticides for their ability to damage bacterial DNA; Rashid KA et al.; Twenty-six pesticides and pesticide degradation products were screened (125 micrograms - 2000 micrograms) for their ability to induce unrepairable damage to bacterial DNA . Three repair test systems were utilized in this study, the Salmonella typhimurium (TA1538/TA1978), the E . coli K-12 (Pol A1+/Pol1-) and the E . coli WP2 (WP2, WP2uvrA, WP67, CM611 and CM571) . Aldicarb (1000 micrograms), benomyl (250 micrograms), 2-aminobenzimidazole (2000 micrograms), captan (125 micrograms), fenazalor (500 micrograms), 5,6-dichloro-2-trifluoromethylbenzimidazole (NC-2983) (250 micrograms), isothymol (250 micrograms), maleic hydrazide (1000 micrograms), pentachloronitrobenzene (1000 micrograms) were DNA-damaging to one or more bacterial test systems . Isothymol and NC-2983 affected all three test systems . Chlorinated hydrocarbon insecticides, some being recognized as carcinogens, did not produce a zone of inhibition in any of the tester strains possibly due to their poor solubility and diffusion in the agar overlay . It was concluded that these tests can be performed along with bacterial reversion tests to complement each other as short-term screening tests for potential carcinogens and mutagens. Environ Health Perspect, 1986 Aug, 67, 93 - 103 A current genotoxicity database for heterocyclic thermic food mutagens . I . Genetically relevant endpoints; Hatch FT; Cooking, heat processing, or pyrolysis of protein-rich foods induce the formation of a series of structurally related heterocyclic aromatic bases that have been found to be mutagens . The primary genetic assay utilized to detect and isolate these mutagens has been the his reversion assay in Salmonella typhimurium . The classification and nomenclature of these chemicals is revised to reflect recent advances . The findings of short-term tests for genetic injury that have been applied to these agents are presented in a systematic way . Cell-free, bacterial, mammalian cell culture, and in vivo systems are included . Major results, the mutagens tested, and key references are presented in tabular form, with text commentary . Integrated conclusions on the state of current knowledge of the genetic toxicity of thermic food mutagens are presented . Areas in need of further research are defined . Finally, an outline is presented of a suggested path leading to the determination whether normal methods of food preparation and processing constitute a human health hazard. Environ Health Perspect, 1986 Aug, 67, 5 - 10 Past, present, and future of mutagens in cooked foods; Sugimura T; Mutation assay with Salmonella typhimurium enabled us to detect various types of mutagens in cooked foods . A series of mutagenic heterocyclic amines has been isolated and identified in broiled fish and meat and in pyrolyzates of amino acids and proteins . Feeding experiments showed these mutagens to be carcinogenic in mice and rats . The mechanism of formation and pathway of metabolic activation of these heterocyclic amines have been elucidated . Their contents in various cooked foods have been determined . The presence of mutagenic nitropyrenes (some of which were confirmed as carcinogens) in grilled chicken was also established . Roasted coffee beans also yield mutagens such as methylglyoxal . The formation of mutagen precursors, including beta-carboline derivatives and tyramine which become mutagens with nitrite treatment, was found during food processing . Oncogene activation in animal tumors induced by some of these food mutagens/carcinogens has been confirmed . The role of mutagens/carcinogens in cooked foods in human cancer development has not yet been exactly evaluated . In order to do this, more information on their carcinogenic potency, human intake, metabolism in the human body, and the effects of combined administration with other initiators, promoters and other modifying factors in food is required. Mutat Res, 1986 Aug-Sep, 171(2-3), 99 - 104 Airplane emissions: a source of mutagenic nitrated polycyclic aromatic hydrocarbons; McCartney MA et al.; Organic solvent extracts from airplane emission particulates are mutagenic for Salmonella typhimurium strain TA98 . Using Salmonella tester strains deficient in enzymes required for the bioactivation of various nitroarenes, the mutagenicity present in these emissions was ascribed to the presence of nitrated polycyclic aromatic hydrocarbons . Based on the known aircraft particulate emission rates at U.S . airports, and using 1-nitropyrene (1-NP) and 1,8-dinitropyrene (1,8-DNP) as surrogates, it is calculated that at a minimum 7 kg 1-NP and 20 g, 1,8-DNP are emitted daily at a typical U.S . airport. Mutat Res, 1986 Aug-Sep, 171(2-3), 63 - 70 Mutagenicity of para-substituted alpha-methylstyrene oxide derivatives with Salmonella; Rosman LB et al.; A series of 5 para-substituted alpha-methylstyrene oxide derivatives have been synthesized and together with alpha-methylstyrene oxide as well as styrene oxide have been studied as to their mutagenicity with the TA100 and TA1535 strains of Salmonella typhimurium . A multiple regression analysis model has been developed which describes the mutagenicity of the alpha-methylstyrene oxides in TA100 . An increase in van der Waals volume was the most important variable in the model with greater improvement occurring with inclusion of the Hammett values for the para substituents on the compounds . The alpha-methylstyrene oxides were less active alkylating agents with 4-(p-nitrobenzyl)pyridine than styrene oxide and with pyridine all reactivity was at the beta-epoxide carbon . However all the alpha-methylstyrene oxide derivatives, except for the bromo compound where toxicity was evident, showed mutagenicity values either greater or comparable to that of styrene oxide . These studies would indicate that reactivity at the beta-carbon should also be a factor in describing the mutagenicity of the parent styrene oxide series. Mutat Res, 1986 Aug-Sep, 171(2-3), 157 - 63 Comparative in vivo and in vitro genotoxicity studies of airborne particle extract in mice; Krishna G et al.; The genotoxicity of an acetone extract of locally collected airborne particles was evaluated both in vitro and in vivo using the sister-chromatid exchange (SCE) assay in mice . At the highest concentration (5.36 mg/5 ml culture), the extract caused approximately a 3-fold increase in SCEs over controls in mouse bone marrow and spleen primary cells in vitro . However, the same airborne particle extract did not induce a significant increase in the SCE level over controls in vivo in mouse bone marrow and spleen cells when administered intraperitoneally or through oral gavage . This indicates that bone marrow and spleen primary cell cultures can be used in in vitro genotoxicity studies of complex mixtures, and that the genotoxicity of airborne particles detected in the in vitro system cannot always be detected in vivo with the same cell types . In addition, the same acetone extract of airborne particles caused dose-related his+ revertants in the strain TA98 of Salmonella typhimurium, both with and without S9 activation . The significant finding of this study is that the in vitro genotoxicity results of airborne particle extract may not be very meaningful in an in vivo situation. Mutat Res, 1986 Aug-Sep, 171(2-3), 123 - 9 Hepatocyte-mediated mutagenicity of mononitrobenzo{a}pyrenes in Salmonella typhimurium strains; Hass BS et al.; The mononitro-substituted isomers of benzo{a}pyrene (B{a}P), 1-, 3- and 6-nitrobenzo{a}pyrene (NB{a}P), are environmental pollutants and are metabolized to mutagens in Salmonella by rat-liver homogenate postmitochondrial supernatant (S9) fractions . In this study, activation of these compounds to mutagens was investigated using the hepatocyte-mediated Salmonella mutagenicity assay . Hepatocytes from rats treated with Aroclor 1254 activated both 3-NB{a}P and 1-NB{a}P to mutagens, while 6-NB{a}P was not mutagenic . The positive mutagenicity responses were functions of both the chemical dose and the hepatocyte concentration . By using a nitroreductase-deficient strain (TA98NR) and a transesterificase-deficient strain (TA98/1,8-DNP6), it was verified that the direct-acting mutagenicities of 1- and 3-NB{a}P primarily were due to metabolic processes involving nitroreduction while the S9- and hepatocyte-mediated mutagenicity responses were also dependent on transesterification . When compared with the mutagenic responses produced with S9, the mutations induced by 1- and 3-NB{a}P in the presence of hepatocytes were relatively more dependent upon nitroreductase metabolism and less on transesterification . Thus, intact hepatocytes were capable of activating 1- and 3-NB{a}P to mutagenic metabolites and some of these metabolites appeared to be different from those produced by S9. Mutat Res, 1986 Aug-Sep, 171(2-3), 105 - 13 Detection of 1-nitropyrene in yakitori (grilled chicken); Kinouchi T et al.; Pieces of raw chicken with or without a marinating sauce were grilled over a city gas flame, extracted with benzene-ethanol (4:1) by ultrasonication and fractionated into diethyl ether-soluble neutral, acidic and basic fractions . The mutagenicity of these fractions was measured with Salmonella typhimurium strains TA100, TA98, TA98NR and TA98/1,8-DNP6 in the presence and absence of a 9000 X g post-mitochondrial supernatant from Aroclor 1254-treated Sprague-Dawley rat liver (S9 mix) . The basic fraction of yakitori without the sauce was more mutagenic than the other fractions for S . typhimurium strain TA98 in the presence of S9 mix . This is probably due to the presence of amino acid or protein pyrolysates . However, when the chicken was grilled with the sauce, the basic fraction showed lower mutagenicity for strain TA98 in the presence of S9 mix than did the same fraction without the sauce . The neutral fraction of yakitori with sauce showed high mutagenicity for strain TA98 in the absence of S9 mix, but low mutagenicity for strains TA98NR and TA98/1,8-DNP6, suggesting that this fraction might contain nitropyrenes (NPs) . The neutral fraction of yakitori was analyzed by high-performance liquid chromatography (HPLC) . The neutral fraction of the chicken grilled with the sauce for 3, 5 and 7 min contained 3.8, 19 and 43 ng, respectively, of 1-NP per gram of yakitori accounting for 3.0, 2.7 and 1.3%, respectively, of the total mutagenicity.(ABSTRACT TRUNCATED AT 250 WORDS) J Clin Microbiol, 1986 Aug, 24(2), 298 - 300 Competitive enzyme-linked immunosorbent assay for cholera-related enterotoxins in Salmonella typhimurium; Hariharan H et al.; We report a rapid competitive enzyme-linked immunosorbent assay to screen Salmonella typhimurium strains for cholera-related enterotoxin antigens . Polymyxin B extracts of bacterial cells from syncase-glucose broth cultures of 7 of 15 strains gave positive results . The specificity of the test was confirmed with known heat-labile-enterotoxin-positive and -negative Escherichia coli strains which gave significantly different values. Proc Natl Acad Sci U S A, 1986 Aug, 83(16), 6169 - 73 In vitro reconstitution of flagellar filaments onto hooks of filamentless mutants of Salmonella typhimurium by addition of hook-associated proteins; Homma M et al.; An in vitro system for reconstituting flagellar filaments onto hooks of filamentless mutants of Salmonella typhimurium was used to investigate the role played in filament formation by the three hook-associated proteins (HAPs, products of the flaW, flaU, and flaV genes) . These proteins--FlaW, FlaU, and FlaV--are believed to be assembled in this order at the distal end of the hook . When the recipient hooks were provided by flaU mutants, whose hook tips contained FlaW only, exogenous FlaU was essential for polymerization of both exogenous and endogenous flagellin, whereas exogenous FlaV inhibited such polymerization . When the recipients were flaV-mutant hooks, whose tips contained FlaW and FlaU but not FlaV, exogenous FlaV inhibited polymerization of exogenous flagellin . FlaV also inhibited polymerization of exogenous flagellin at the tips of filament fragments . In contrast, FlaV was essential for polymerization of endogenous flagellin onto flaV-mutant hooks, and onto short filaments that had been made (in the absence of FlaV) by polymerization of exogenous flagellin on the tips of flaV-mutant hooks . These results suggest that FlaV acts not only at the tip of the hook to initiate growth of the filament, but also at the tip of the growing filament, and that FlaV is essential for polymerization of endogenous flagellin--i.e., for the normal process of filament assembly in vivo. Mutat Res, 1986 Aug, 174(4), 259 - 63 An internal survival standard for Salmonella typhimurium forward mutation assays; Maliniack M et al.; A novel S . typhimurium forward mutation assay which avoids plating density artifacts is described . The new method uses a pair of multiply drug-resistant substrains of TM677, a bacterial strain used in previous forward mutation studies . This technique permits the measurement of cell survival following mutagen treatment by plating the culture on specially supplemented plates at the same cell concentration used to measure mutant yield . Thus this method is both technically easier and theoretically superior to our previous method. Mutat Res, 1986 Aug, 174(4), 255 - 8 Mutagenicity of soy sauce treated with a physiologically feasible concentration of nitrite; Tahira T et al.; Soy sauce treated with nitrite was found to be more mutagenic to Escherichia coli WP2 uvrA/pKM101 than Salmonella typhimurium TA100 without S9 mix . The mutagenicity of soy sauce treated with nitrite was affected by the concentration of soy sauce in the nitrosation mixture, and a concentration of 5% resulted in the highest specific activity (revertants/ml soy sauce equivalent) . By incubating soy sauce at a concentration of 5% in a solution of 1 mM nitrite at pH 3 for 1 h at 37 degrees C, the equivalent of 1 ml of soy sauce induced 2790 revertants of E . coli WP2 uvrA/pKM101 without S9 mix. J Med Microbiol, 1986 Aug, 22(1), 39 - 49 The nature and role of mucosal damage in relation to Salmonella typhimurium-induced fluid secretion in the rabbit ileum; Wallis TS et al.; The time course and nature of mucosal damage induced in rabbit ileal loops by two strains of Salmonella typhimurium (TML and W118) isolated from human infections was assessed by immunofluorescence microscopy and by scanning and transmission electronmicroscopy . Salmonella-induced fluid secretion occurred in the presence or absence of gross mucosal architectural damage . Neither strain caused mucosal ulceration . When damage did occur, the villi were shortened by loss of their tip regions with concomitant reforming of an intact mucosal surface . Immediately preceding the onset of fluid secretion, marked infiltration of the mucosa with polymorphonuclear leukocytes and occasional macrophages was seen . This revives an earlier suggestion that interaction between invading salmonellae and acute inflammatory cells may be an important factor in initiation of fluid secretion . Brush-border invasion by salmonellae cannot per se be the immediate cause of fluid secretion, because the latter occurred several hours after initial invasion. J Bacteriol, 1986 Aug, 167(2), 639 - 46 crp genes of Shigella flexneri, Salmonella typhimurium, and Escherichia coli; Cossart P et al.; The complete nucleotide sequences of the Salmonella typhimurium LT2 and Shigella flexneri 2B crp genes were determined and compared with those of the Escherichia coli K-12 crp gene . The Shigella flexneri gene was almost like the E . coli crp gene, with only four silent base pair changes . The S . typhimurium and E . coli crp genes presented a higher degree of divergence in their nucleotide sequence with 77 changes, but the corresponding amino acid sequences presented only one amino acid difference . The nucleotide sequences of the crp genes diverged to the same extent as in the other genes, trp, ompA, metJ, and araC, which are structural or regulatory genes . An analysis of the amino acid divergence, however, revealed that the catabolite gene activator protein, the crp gene product, is the most conserved protein observed so far . Comparison of codon usage in S . typhimurium and E . coli for all genes sequenced in both organisms showed that their patterns were similar . Comparison of the regulatory regions of the S . typhimurium and E . coli crp genes showed that the most conserved sequences were those known to be essential for the expression of E . coli crp. Eur J Biochem, 1986 Aug 1, 158(3), 561 - 7 Peptide uptake by Salmonella typhimurium . The periplasmic oligopeptide-binding protein; Hiles ID et al.; The uptake of most peptides, including many peptide antibiotics, by the oligopeptide permeases of Escherichia coli and Salmonella typhimurium requires the function of a specific peptide-binding protein (the OppA protein) located within the periplasm . The OppA protein is the largest and most abundant periplasmic substrate-binding protein known and has an unusually broad substrate-binding specificity . The OppA protein has been purified to homogeneity and anti-OppA antibodies have been raised . The sequence of the OppA protein has been deduced from the nucleotide sequence of the oppA gene . This protein is unrelated to any other known periplasmic substrate-binding protein, either immunologically or in its amino acid sequence . The role of this protein in peptide transport is discussed. Carcinogenesis, 1986 Aug, 7(8), 1339 - 44 Mutagenicity of 3,4-diphenyl-5-nitrofuran analogs in Salmonella typhimurium; Ichikawa M et al.; A new series of chemicals comprising eight different 3,4-diphenyl-substituted furan analogs, namely, methyl-3,4-diphenyl-2-furoate, methyl-3,4-diphenyl-5-nitro-2-furoate, 3,4-diphenyl-5-nitro-2-furoic acid, 3,4-diphenyl-5-nitro-2-acetylfuran, 3,4-diphenyl-5-nitro-2-bromoacetylfuran, 2-amino-4-(3,4-diphenyl-5-nitro-2-furyl)thiazole, 2-acetyl-amino-4-(3,4-diphenyl-5-nitro-2-furyl)thiazole and 2-formyl-amino-4-(3,4-diphenyl-5-nitro-2-furyl)thiazole were synthesized and their mutagenic activities tested in Salmonella typhimurium . The structure--activity relationship studies revealed that for mutagenic activity the nitro group is essential and that the potency of activity is greatly altered by the nature of the substituent at the 2-position of the furan ring . The mutagenic activities of these chemicals were generally much higher in TA100 compared to TA98 . The relative order of activities for 2-substituted, 3,4-diphenyl-5-nitrofurans were COOCH3 greater than COCH2BR greater than COCH3 greater than COOH in S . typhimurium TA100 . 3,4-Diphenyl-5-nitro-2-bromoacetylfuran was equally active in nitroreductase-proficient (TA98, TA100) and in nitroreductase-deficient (TA98NR, TA100NR) strains . In contrast, the acetyl and carboxymethyl ester analogs were relatively less active in nitroreductase-deficient strains . Mutagenic activities of 3,4-diphenyl-substituted furylthiazoles in comparison with the unsubstituted analogs of N-{4-(5-nitro-2-furyl)-2-thiazolyl}-formamide, N-{4-(5-nitro-2-furyl)-2-thiazolyl}-acetamide and 2-amino-4-(5-nitro-2-furyl)thiazole revealed that the phenyl groups drastically reduced their mutagenic activities . However, the relative order of activities formylamino greater than or equal to acetylamino greater than amino were the were the same between phenyl-substituted and unsubstituted analogs. J Bacteriol, 1986 Aug, 167(2), 616 - 22 Cloning and DNA sequence analysis of the wild-type and mutant cyclic AMP receptor protein genes from Salmonella typhimurium; Schroeder CJ et al.; The crp gene from Salmonella typhimurium, as well as two mutant adenylate cyclase regulation genes designated crpacr-3 and crpacr-4, were cloned into the EcoRI site of plasmid pUC8 . Initially cloned on 5.6-kilobase fragments isolated from EcoRI digests of chromosomal DNA, these genes were further subcloned into the BamHI-EcoRI site of plasmid pBR322 . When tested, Escherichia coli crp deletion strains harboring the clones regained their ability to pleiotropically ferment catabolite-repressible sugars . Also, the crpacr-containing strains displayed sensitivity to exogenous cyclic AMP (cAMP) when grown on eosin-methylene blue medium with xylose as the carbon source . The proteins encoded by the S . typhimurium wild-type and mutant crp genes were found to have similar molecular weights when compared with the wild-type cAMP receptor protein (CRP) from E . coli . DNA sequence analysis of the wild-type crp gene showed only a three-nucleotide difference from the E . coli sequence, suggesting little divergence of the crp gene between these organisms . The crpacr sequences, however, each contained single nucleotide changes resulting in amino acid substitutions at position 130 of the CRP . Based on the site at which these substitutions occur, the crpacr mutations are believed to affect CRP-cAMP interactions. Biochem Biophys Res Commun, 1986 Jul 31, 138(2), 505 - 11 Frameshift mutagenesis in Salmonella typhimurium by reversible DNA intercalators: effect of a UVR B mutation; Rene B et al.; The simple reversible intercalating agents isopropyl-oxazolopyridocarbazole and 9-aminoacridine have been found to induce frameshift -1 mutations at a much lower level in Salmonella typhimurium delta uvrB TA 1537 than in the uvr+ wild type TA 1977 strain . This phenomenon can neither be explained by differential cytotoxicity of the drug nor by selective permeation and accessibility to intercalating sites to bacterial DNA . These finding indicate that the lower mutagenicity of intercalating agents in the delta uvrB strains does not result from nonspecific phenotypic modifications of parameters which control the mutagenesis . That leads to the hypothesis that in agreement with the Streisinger's model, the excision repair system could be directly involved in the appearance of frameshift mutations. Biochemistry, 1986 Jul 29, 25(15), 4233 - 40 Beta-elimination of indole from L-tryptophan catalyzed by bacterial tryptophan synthase: a comparison between reactions catalyzed by tryptophanase and tryptophan synthase; Ahmed SA et al.; Although tryptophan synthase catalyzes a number of pyridoxal phosphate dependent beta-elimination and beta-replacement reactions that are also catalyzed by tryptophanase, a principal and puzzling difference between the two enzymes lies in the apparent inability of tryptophan synthase to catalyze beta-elimination of indole from L-tryptophan . We now demonstrate for the first time that the beta 2 subunit and the alpha 2 beta 2 complex of tryptophan synthase from Escherichia coli and from Salmonella typhimurium do catalyze a slow beta-elimination reaction with L-tryptophan to produce indole, pyruvate, and ammonia . The rate of the reaction is about 10-fold higher in the presence of the alpha subunit . The rate of indole production is increased about 4-fold when the aminoacrylate produced is converted to S-(hydroxyethyl)-L-cysteine by a coupled beta-replacement reaction with beta-mercaptoethanol . The rate of L-tryptophan cleavage is also increased when the indole produced is removed by extraction with toluene or by condensation with D-glyceraldehyde 3-phosphate to form indole-3-glycerol phosphate in a reaction catalyzed by the alpha subunit of tryptophan synthase . The amount of L-tryptophan cleavage is greatest in the presence of both beta-mercaptoethanol and D-glyceraldehyde 3-phosphate, which cause the removal of both products of cleavage . The cleavage reaction is not due to contaminating tryptophanase since the activity is not inhibited by (3R)-2,3-dihydro-L-tryptophan, a specific inhibitor of tryptophanase, but is inhibited by (3S)-2,3-dihydro-L-tryptophan, a specific inhibitor of tryptophan synthase . The cleavage reaction is also inhibited by D-tryptophan, the product of a slow racemization reaction.(ABSTRACT TRUNCATED AT 250 WORDS) Biochem Pharmacol, 1986 Jul 15, 35(14), 2313 - 22 Inhibition of the mutagenicity and metabolism of 6-methyl-benzo{a}pyrene and 6-hydroxymethyl-benzo{a}pyrene; Bayless JH et al.; Previously reported inhibitors of benzo{a}pyrene (BaP) mutagenicity in Salmonella typhimurium strain TA98 were tested for their effectiveness against the mutagenicity of 6-methyl-benzo{a}pyrene (6-CH3-BaP), 6-hydroxymethyl-benzo{a}pyrene (6-CH2OH-BaP) and 6-acetoxymethyl-benzo{a}pyrene (6-CH3COOCH2-BaP) . Dose-response curves obtained for phenothiazine (PTH), 2-chlorophenothiazine (2Cl-PTH), phenylisothiocyanate (PHN), phenethylisothiocyanate (PNE), trans-retinol (TR) and disulfiram (TETD) showed a variety of degrees of inhibition of mutagenicity . Additionally, glutathione (GSH) was found to inhibit the mutagenicity of 6-CH3COOCH2-BaP, and the mutagenicity of 6-CH2OH-BaP was enhanced by the addition of supplemental ATP, Na2SO4 and EDTA . Only 2Cl-PTH was equally as good an inhibitor of 6-CH3-BaP and BaP, reducing revertant colonies to less than 50% of control at 10 X BaP concentration . To probe the mechanism of inhibition, the effect of 2Cl-PTH on the binding of BaP and the 6-substituted benzo{a}pyrenes to cytochrome P-450 was investigated by difference spectroscopy . Also, the effect of 2Cl-PTH on the subsequent metabolism of 6-CH3-BaP and 6-CH2OH-BaP was investigated by rapid scan difference spectroscopy and high-performance liquid chromatographic separation of products . The results are consistent with a major mechanism of inhibition for 2Cl-PTH involving a competition for the cytochrome P-450 binding site. J Comp Pathol, 1986 Jul, 96(4), 379 - 86 An in vivo and in vitro study of selenium deficiency and infection in rats; Boyne R et al.; Selenium deficiency in rats impairs the ability of neutrophils and peritoneal macrophages to kill Candida albicans organisms in vitro . In contrast, killing of Salmonella typhimurium and Staphylococcus aureus organisms is unaffected by the deficiency . Survival of rats after intraperitoneal injection of 8 X 10(7) S . aureus organisms was not affected by Se deficiency, but a 5-fold increase in the dose (4 X 10(8) S . aureus organisms) led to a significantly greater mortality in the Se deficient rats. Infect Immun, 1986 Jul, 53(1), 26 - 31 Yersinia enterocolitica infection in resistant and susceptible strains of mice; Hancock GE et al.; We investigated natural resistance in mice to Yersinia enterocolitica, an enteric bacterial pathogen of humans, with a view to determine host genetic factors that are important in resistance . Most mouse strains studied (C3H/HeN, BALB/c, BALB.B, DBA/2, A, Swiss, and SWR) were highly susceptible to infection (50% lethal dose {LD50}, 2 X 10(2) to 6 X 10(2) Y . enterocolitica administered intravenously {i.v.}) . In contrast, C57BL/6 mice were highly resistant (LD50, 2 X 10(5) Y . enterocolitica administered i.v.) . Resistance to i.v . Yersinia infection did not appear to be related to the Ity locus (which codes for resistance to Salmonella typhimurium and other pathogens) because Ityr mice (C3H/HeN, DBA/2, A, and SWR) were more susceptible to Y . enterocolitica than were Itys (C57BL/6) mice . In addition, because BALB.B mice (congenic to C57BL/6 mice at the H-2 locus) were susceptible, resistance was probably not H-2 linked . BALB/c X C57BL/6 F1 mice were intermediate in their resistance to Y . enterocolitica infection (LD50, 3 X 10(4) organisms administered i.v.), suggesting that resistance to Y . enterocolitica depends on a gene dosage affect or a resistance gene(s) interaction between susceptible and resistant parents . Further studies with C57BL/6 and BALB/c mice as prototype resistant and susceptible strains were undertaken . A time course study of Y . enterocolitica growth in various organs following i.v . infection revealed no strain difference in bacterial growth during the first 48 h of infection . Thereafter, however, C57BL/6 mice were capable of restricting Y . enterocolitica growth in all tissues (liver, lung, spleen, kidneys), whereas extensive bacterial proliferation occurred in BALB/c mice tissues . BALB/c mice were also more susceptible to oral Y . enterocolitica infection than were C57BL/6 mice, demonstrating increased mortality and greater numbers of bacteria in the Peyer's patches . Finally, whereas thymus-bearing C57BL/6 X BALB/c F1 mice were resistant to infection, athymic (nude) C57BL/6 X BALB/c F1 mice were susceptible . These studies provide a model to investigate natural immunity to enteric pathogens at mucosal surfaces, as well as provide the basis for clarifying the role of host genotype in Y . enterocolitica resistance. J Med Chem, 1986 Jul, 29(7), 1319 - 21 Isolation, synthesis, and antitumor evaluation of spirohydantoin aziridine, a mutagenic metabolite of spirohydantoin mustard; Struck RF et al.; Spirohydantoin mustard (SHM), a central nervous system directed nitrogen mustard with anticancer activity, was metabolized in the presence of mouse liver postmitochondrial supernatant (9000g fraction) to a nonpolar alkylating metabolite . The metabolite was isolated by thin-layer chromatography of chloroform or ethyl acetate extracts of incubation mixtures, and its structure was established by mass spectral analysis, synthesis, and cochromatography . The metabolite, spirohydantoin aziridine, was mutagenic for Salmonella typhimurium TA1535 in the Ames assay but inactive as an antitumor agent against P388 leukemia in vivo. J Appl Bacteriol, 1986 Jul, 61(1), 51 - 6 Laboratory studies on salmonella-contaminated cheese involved in a major outbreak of gastroenteritis; Ratnam S et al.; A major outbreak of gastroenteritis was traced to Cheddar cheese contaminated with Salmonella typhimurium . There were no significant differences in pH values of the contaminated (mean pH 5.31) and non-contaminated (mean pH 5.39) cheese . The isolation rates of Salm . typhimurium were about the same when cheese samples were homogenized in lactose broth, lactose broth containing 1% Tween 80, or in aqueous 2% sodium citrate . Salmonella typhimurium was isolated regardless of preenrichment in lactose broth, but required selective enrichment in selenite cystine or tetrathionate brilliant green broth . There were no marked differences in the isolation rates obtained with different selective enrichment media, or after incubation at 36 degrees and 43 degrees C for 24 or 48 h . Contaminated samples of cheese failed to yield Salm . typhimurium consistently despite large and multiple samplings; samples from the interior of cheese blocks yielded positive results more frequently than the samples from the exterior . The number of Salm . typhimurium in factory sealed blocks as well as in samples obtained from the homes of known cases of salmonellosis was found to range from less than 3/100 g to 9/100 g of cheese . The infective dose of Salm . typhimurium in contaminated cheese was probably no greater than 10(4) organisms, and a rapid decline in numbers of Salm . typhimurium must have occurred subsequent to the outbreak. Ann Inst Pasteur Immunol, 1986 Jul-Aug, 137D(1), 93 - 107 Increased phagocytic activity in mice treated by a mouse granuloma protein; Fontan E et al.; Intravenous injection of a protein extracted from a talc-induced granuloma (MGP) enhanced the blood clearance of a highly virulent strain of Salmonella typhimurium . This protein was able to enhance mouse resistance to systemic infection with Listeria monocytogenes when injected one or two days prior to infection . Furthermore, since MGP-treated athymic mice were also protected against Listeria infection, mature T cells were most likely not involved in this enhanced resistance . These findings suggest that this increased resistance to infection correlates with an activation of liver and spleen macrophages . This protective effect of MGP was not due to possible endotoxin contamination of the preparation, as the MGP activity was destroyed by heating. Immunology, 1986 Jul, 58(3), 379 - 87 Functional characteristics of the veiled cells in afferent lymph from the rat intestine; Mayrhofer G et al.; Non-lymphoid veiled cells (VC) in the thoracic duct lymph from mesenteric lymphadenectomized rats have been studied by light microscopy, enzyme histochemistry and scanning electron microscopy . These cells arise in the afferent lymph from the intestine . They have been semi-purified and examined for expression of Ia antigens using an indirect immunoperoxidase technique and monoclonal antibodies . Accessory cell function necessary for mitogen-induced blastogenesis in the thoracic duct lymph from these animals has been correlated with the presence of VC by depletion and reconstitution experiments . Similar results were obtained with lymphocyte suspensions from other rat lymphoid organs and they are contrasted with those from studies on mouse lymphoid cells . Antigen presentation in a secondary in vitro lymphoproliferative assay was also depleted from immunized lymph node cells by removal of endogenous VC and can be reconstituted in a dose-dependent fashion with antigen-pulsed VC from afferent intestinal lymph . In contrast, reconstitution of both mitogen-induced blastogenesis and antigen-induced lymphoproliferation with peritoneal exudate cells was poor, while at high multiplicities of added macrophages, such cells were inhibitory . Afferent intestinal lymph VC were found to transport bacteria and bacterial antigen in rats infected with Salmonella typhimurium . The results are discussed in relation to the lineage of the VC in intestinal afferent lymph, their function as accessory cells and their possible physiological role in transporting antigens from the gut to its regional lymph nodes. Fundam Appl Toxicol, 1986 Jul, 7(1), 1 - 16 Regulatory implications of Ames' mutagenicity assay using Salmonella typhimurium; Jackson BA et al.; Interpretive difficulties can be expected when molecular biology and modern genetics are applied to the safety evaluation of chemicals . Experience, in a regulatory setting, with evaluating the results of short term tests, such as Ames' mutagenicity assay using Salmonella typhimurium (Ames' assay), shows that the traditional toxicological paradigm for interpreting and evaluating the results of such tests is less than adequate . The considerable importance of a negative test outcome to the public health as well as to the course of the commercial development of a potentially useful chemical places special demands on both the investigator and the regulatory reviewer for an understanding of Ames' assay . The adequate design, conduct, interpretation, and evaluation of the outcomes of this assay require a knowledge of the chemical properties of the test agent, an understanding of the scientific basis of the test, and an appreciation of the extent to which modifications of the assay can alter the outcome . The investigator and the regulatory reviewer use the same considerations to determine the adequacy of the test design and of the test results . However, a fundamental difference exists between how they interpret results and how they view the outcome . Results from a study comparing activation systems from food animal and laboratory animal sources are used to illustrate the complexity of using safety data from a genetic test . A framework is developed to suggest how to accommodate the points of view of the investigator and the regulatory reviewer in evaluating these data. Proc Natl Acad Sci U S A, 1986 Jul, 83(14), 5189 - 93 Mutants of Salmonella typhimurium that cannot survive within the macrophage are avirulent; Fields PI et al.; Salmonella typhimurium is a facultative intracellular pathogen capable of surviving within phagocytic cells of the reticuloendothelial system . To identify the genes important for intracellular survival, 9516 independent Tn10 insertional mutations were isolated in a virulent strain of S . typhimurium . By using an in vitro assay for survival within macrophages, 83 Tn10 mutants have been identified that have a diminished capacity for intracellular survival (designated MS or macrophage survival mutants) . All of the MS mutants are less virulent than the parent strain in vivo, demonstrating that, for Salmonella, survival within the macrophage is essential for virulence . Thirty-seven of the MS mutants have been characterized as to their phenotype, including several mutations that confer sensitivity to specific microbiocidal mechanisms of the macrophage. Mutat Res, 1986 Jul, 174(3), 169 - 73 Genetic activity of 2-aminofluorene in the salmonella/erythrocyte mutagenicity assay; Cantelli-Forti G et al.; In a previous study, we demonstrated the activation of cyclophosphamide by mouse erythrocytes in a yeast test using the D7 strain of Saccharomyces cerevisiae . The present study provides further information on the ability of washed red blood cells from mice to activate 2-aminofluorene (2-AF) detected as an increase in mutation frequency of the tester strain, TA1538 (frameshift mutation) of Salmonella typhimurium . The 2-AF was tested at different concentrations (1-8 micrograms/plate) using both the liquid-suspension test and the agar-plate test . For comparison, the bioactivation of 2-AF by the hepatic postmitochondrial supernatant (S9 fraction) from Aroclor-1254-induced rats was studied . 2-AF was only found to be clearly mutagenic in the agar-plate test with both activation systems . The genetic response obtained with the erythrocytes appeared to be related to the number of cells/plate . At the lowest dose, slight differences are observed when genotoxic effects were compared to those with the S9 fraction. J Bacteriol, 1986 Jul, 167(1), 420 - 2 Mutant of Salmonella typhimurium LT2 deficient in DNA adenine methylation; Ritchie LJ et al.; A mutant of Salmonella typhimurium LT2 deficient in methylation of the adenine residues in the sequence 5'-GATC-3' was isolated . The mutation (dam-1) was linked to the cysG locus, and the properties of the mutant were similar to those of Escherichia coli dam mutants . Reversion of the hisC3076 frameshift marker by 9-aminoacridine was substantially enhanced by the dam-1 mutation, implying a direct role for adenine methylation in the prevention of frameshift mutation induction. Carcinogenesis, 1986 Jul, 7(7), 1239 - 41 Synthesis and mutagenicity of 3,3'-dihalogenated benzidines; Savard S et al.; 3,3'-Difluorobenzidine (F2Bz), and 3,3'-dibromobenzidine (Br2Bz) were synthesized and compared with 3,3'-dichlorobenzidine (Cl2Bz) for ability to revert Salmonella typhimurium . The relative mutagenicities in all systems are Cl2Bz approximately equal to Br2Bz greater than F2Bz greater than Bz . F2Bz, Cl2Bz, and Br2Bz are direct-acting mutagens towards S . typhimurium strain TA98 . The acetylase-deficient derivative TA98/1,8-DNP6 displays no resistance to induction of mutagenesis by these compounds, in the absence of mammalian activation . With addition of hamster hepatic S-9 activation the mutagenicity of these compounds increases greatly . TA98/1,8-DNP6 shows some resistance to this mutagenicity . Multiple mechanisms must exist for the genotoxicity of 3,3'-dihalogenated benzidines. Mutagenesis, 1986 Jul, 1(4), 267 - 73 Conditions for the optimal use of the L-arabinose-resistance mutagenesis test with Salmonella typhimurium; Hera C et al.; Different conditions of mutagenesis have been compared in order to optimize the use of the L-arabinose resistance test with Salmonella typhimurium . The mutagenesis protocols compared were the plate-incorporation, the pre-incubation and the liquid tests . Fourteen chemicals were used in the comparison: six direct-acting mutagens and eight pre-mutagens . Five concentrations of S9 (3, 7.5, 10, 15 and 33% v/v) were compared in the liquid test with pre-mutagens, and three densities of bacteria (ranging from 10(8) to 10(6) cells) were used in the comparison between the plate-incorporation and the pre-incubation mutagenesis test . In general, the liquid test proved the most sensitive mutagenesis protocol . When carrying out this test in a mass screening of mutagens, we propose to select the L-arabinose-resistant mutants in plates supplemented with 0.5 mg of D-glucose, and to express the mutagenic response as the absolute number of induced mutants . The plate-incorporation and the pre-incubation mutagenesis protocols could be considered as alternative procedures in the case of previous negative results with the liquid test . Two recommendations can be finally made in order to avoid false negative results: (a) a large population of bacteria (ranging from 10(8) to 10(7) cells) must be exposed to the mutagens in both the plate-incorporation and the pre-incubation mutagenesis tests, and (b) ideally, several S9 concentrations (ranging from 3 to 30% v/v) would be employed for testing in liquid samples of unknown mutagenicity. Mutagenesis, 1986 Jul, 1(4), 275 - 82 Computer-automated prediction of the mutagenicity of benzidine, 4,4"-diaminoterphenyl, 4-dimethylaminoazobenzene and 4-cyanodimethylaniline: comparison with the results of the Second UKEMS Collaborative Study; Rosenkranz HS et al.; There was agreement between the experimental results, obtained i