J Bacteriol, 1989 Apr, 171(4), 2049 - 55 An alkyl hydroperoxide reductase induced by oxidative stress in Salmonella typhimurium and Escherichia coli: genetic characterization and cloning of ahp; Storz G et al.; The ahp genes encoding the two proteins (F52a and C22) that make up an alkyl hydroperoxide reductase were mapped and cloned from Salmonella typhimurium and Escherichia coli . Two classes of oxidant-resistant ahp mutants which overexpress the two proteins were isolated . ahp-1 was isolated in a wild-type background and is dependent on oxyR, a positive regulator of defenses against oxidative stress . ahp-2 was isolated in an oxyR deletion background and is oxyR independent . Transposons linked to ahp-1 and ahp-2 or inserted in ahp mapped the genes to 13 min on the S . typhimurium chromosome, 59% linked to ent . Deletions of ahp obtained in both S . typhimurium and E . coli resulted in hypersensitivity to killing by cumene hydroperoxide (an alkyl hydroperoxide) and elimination of the proteins F52a and C22 from two-dimensional gels and immunoblots . ahp clones isolated from both S . typhimurium and E . coli complemented the cumene hydroperoxide sensitivity of the ahp deletion strains and restored expression of the F52a and C22 proteins . A cis-acting element required for oxyR-dependent, rpoH-independent heat shock induction of the F52a protein was present at the S . typhimurium but not the E . coli ahp locus. Carcinogenesis, 1989 Apr, 10(4), 733 - 6 Mutagenicity and carcinogenicity of smoked meat from Nagaland, a region of India prone to a high incidence of nasopharyngeal cancer; Sarkar S et al.; The incidence of nasopharyngeal cancer (NPC) in the northeastern part of India is reported to be high . A possible correlation between consumption of smoked meat by the tribal people and high suceptibility to NPC has been postulated . The charred portion of smoked beef and meat of other animals was collected from this area, extracted with acetone and the extract (SME) was tested using the Ames test as well as for chromosomal aberration in mouse bone marrow cells and carcinogenicity using Swiss bare mice . It was observed that SME was mutagenic in all five strains of Salmonella typhimurium (TA98, TA1538, TA100, TA1535 and TA1537), with or without S9 mix, and was clastogenic in a mammalian test system . SME also has the potential to induce skin papilloma as well as systemic tumours in Swiss bare mice . Chemical analysis of SME revealed the presence of low concentrations of volatile nitrosamines. Arch Biochem Biophys, 1989 Apr, 270(1), 77 - 83 Effect of spermidine on the development of bacteriophage SP6; Verma M; Bacteriophage SP6 is a virulent phage of Salmonella typhimurium which behaves differently than other phages of the same host . The effect of spermidine on SP6 infection of S . typhimurium has been found to depend on the time of addition of spermidine with respect to the time of addition of the phage and also on the composition of the growth medium . If spermidine was added prior to or within a short time after infection, the cells survived . Under this condition the invading DNA appeared to remain trapped in the cell membrane, and there was no expression of the phage genome . If spermidine was added after the initiation of the infection process, the replication of the phage was inhibited but the cells did not survive . Furthermore, if spermidine was added after DNA synthesis was over, there was no effect of spermidine on phage multiplication . Spermidine was found to affect phage DNA synthesis but not host DNA synthesis. Cancer Res, 1989 Apr 1, 49(7), 1778 - 82 Influence of the alkyl substituent on mutagenicity and covalent DNA binding of bay region diol-epoxides of 7-methyl- and 7-ethylbenz(a)anthracene in Salmonella and V79 Chinese hamster cells; Glatt H et al.; The anti-isomers of the bay region diol-epoxides of the strong carcinogen 7-methylbenz(a)anthracene and of the weak carcinogen 7-ethylbenz(a)anthracene were investigated for mutagenicity in Salmonella typhimurium (reversion of the his - strains TA98 and TA100 to prototrophy) and V79 Chinese hamster cells (acquisition of resistance to 6-thioguanine and ouabain; formation of micronuclei) . In addition, in the V79 cells, the levels of the DNA adducts formed were determined by 32P-postlabeling analysis . In terms of mutations per nmol compound administered, the methyl derivative was four to 10 times more potent, depending on the genetic endpoint, than its ethyl congener . However, when the results were expressed as mutations per adduct, the difference between the two diol-epoxides was small . Therefore, a higher level of DNA modification appears to be the major reason for the stronger mutagenicity of the methyl derivative . However, both diol-epoxides had similar half-lives (about 9 min) in physiological buffer, as determined from the decline in mutagenic activity after preincubation of the test compound . These results suggest that the effect of the 7-alkyl group on the extent of reaction with DNA is more a result of steric factors than of a change in the intrinsic chemical reactivity of the diol-epoxides. J Gen Microbiol, 1989 Apr, 135 ( Pt 4), 1017 - 25 Chemical and biological properties of lipopolysaccharide, lipid A and degraded polysaccharide from Wolinella recta ATCC 33238; Kumada H et al.; Lipopolysaccharide (LPS) was isolated and purified from Wolinella recta ATCC 33238 by the phenol-water procedure and RNAase treatment . The sugar components of the LPS were rhamnose, mannose, glucose, heptose, 2-keto-3-deoxyoctonate (KDO) (3-deoxy-D-manno-octulosonate) and glucosamine . The degraded polysaccharide prepared from LPS by mild acid hydrolysis was fractionated by Sephadex G-50 gel chromatography into three fractions: (1) a high-molecular-mass fraction, eluting just behind the void volume, consisting of a long chain of rhamnose (22 mols per 3 mols of heptose residue) with attached core oligosaccharide; (2) a core oligosaccharide containing heptose, glucose and KDO, substituted with a short side chain of rhamnose; (3) a low-molecular-mass fraction containing KDO and phosphate . The main fatty acids of the lipid A were C12:0, C14:0, 3-OH-C14:0 and 3-OH-C16:0 . The biological activities of the LPS were similar to those of Salmonella typhimurium LPS in activation of the clotting enzyme of Limulus amoebocytes, the Schwartzman reaction and mitogenicity for murine lymphocytes, although all the biological activities of lipid A were lower than those of intact LPS. Genetics, 1989 Apr, 121(4), 635 - 49 The isolation and sequence of missense and nonsense mutations in the cloned bacteriophage P22 tailspike protein gene; Schwarz JJ et al.; Twenty-seven new mutations in the structural gene for the Salmonella typhimurium bacteriophage P22 tailspike protein have been isolated, mapped using a powerful plasmid-based genetic system and their DNA sequence changes determined . The mutations were generated by hydroxylamine treatment of the cloned gene on a plasmid expression vector . Assaying the activity of the tailspike protein produced from this plasmid and screening for plasmid mutants were accomplished by the in situ complementation of P22 capsids imbedded in soft agar to produce infectious phage . Deletion mutations in the cloned gene have been constructed by a two step procedure involving oligonucleotide linker insertion and in vitro deletion by restriction endonuclease digestion . The deletions, whose physical endpoints were determined by DNA sequencing, define 12 genetic and physical intervals into which the new mutations were mapped by marker rescue experiments . These deletions were transferred to phage P22 by recombination and used to map mutations carried on plasmids . Following mapping, the nucleotide change for each of the mutations was determined by DNA sequencing . The majority were absolute missense mutations although both amber and ochre nonsense mutations were also identified in the protein coding portion of the gene . The suppression pattern of the nonsense mutations was determined on several nonsense suppressors . Four of the mutations cause severely depressed levels of tailspike protein expression from both the cloned gene on the plasmid expression vector and from P22 phage carrying these mutations . These mutations were identified as nucleotide changes in what is probably the P22 late operon transcription terminator which immediately follows the tailspike protein coding sequence. FEMS Microbiol Immunol, 1989 Apr, 1(5), 279 - 84 Susceptibility of Salmonella typhimurium and Salmonella typhi to oxygen metabolites; Ishibashi Y et al.; The susceptibility of Salmonella typhimurium LT2 and S . typhi 1079 to oxygen metabolites were compared . S . typhimurium LT2 and S . typhi 1079 were killed to an equal extent (about 40%) by the xanthine-xanthine oxidase (200 mU/ml) system . Among the various scavengers of oxygen metabolites, catalase alone inhibited the killing of S . typhimurium LT2 and S . typhi 1079 by the xanthine-xanthine oxidase system, indicating that hydrogen peroxide contributed to the killing of Salmonellae . The respiratory burst of murine macrophages was efficiently triggered by the ingestion of S . typhimurium LT2, S . typhimurium SL1102, and S . typhi 1079 and all to the same extent . However, in the range of the concentration of hydrogen peroxide produced by murine macrophages, neither S . typhimurium LT2 nor S . typhi 1079 were killed . Only S . typhimurium SL1102, a rough mutant of S . typhimurium LT2, was markedly susceptible under these conditions . The findings suggest that both S . typhimurium LT2 and S . typhi 1079 are resistant to oxygen-dependent killing mechanisms. Mol Gen Genet, 1989 Apr, 216(2-3), 517 - 25 The PEP: fructose phosphotransferase system in Salmonella typhimurium: FPr combines enzyme IIIFru and pseudo-HPr activities; Geerse RH et al.; We have cloned the fru operon of Salmonella typhimurium, coding for the enzymes of the phosphoenolpyruvate: fructose phosphotransferase system (Fructose PTS) . The fruFKA operon consists of three genes: fruF coding for FPr, fruK for fructose 1-phosphate kinase and fruA for Enzyme IIFru . Insertions of Tn5 in the different genes were isolated and the activities of the gene products were measured . Expression of the plasmid-encoded fru operon in the maxicell system resulted in the synthesis of three proteins with molecular weights of 47 kDa (fruA), 39 kDa (fruF) and 32 kDa (fruK) . We have sequenced the fruF gene and the regulatory region of the fru operon . In contrast to previously published results, we have found that the fruF gene codes for a 39 kDa protein, FPr, that combines Enzyme IIIFru and pseudo-HPr activities . The N-terminal part of FPr is homologous to the cytoplasmic domain of the Escherichia coli Enzyme IIMtl, as well as several Enzymes IIIMtl from gram-positive bacteria . The C-terminal domain shows homology to HPr of E . coli and several gram-positive organisms . The fru operon is regulated by a repressor, FruR . We have constructed an operon fusion between fru and the galK gene and shown that regulation of the fru operon by FruR takes place at the level of transcription. Mol Gen Genet, 1989 Apr, 216(2-3), 210 - 6 Absence of insertions among spontaneous mutants of Salmonella typhimurium; Casadesus J et al.; While insertion sequences (IS) in Escherichia coli transpose frequently to generate spontaneous insertion mutants, such mutations are rare in Salmonella typhimurium: the only documented insertion mutation is a hisD mutation caused by the Salmonella-specific IS element IS200 . To obtain more examples of IS200 insertion mutations and to seek additional types of IS elements in Salmonella, we selected and characterized 422 independent, spontaneous His- mutants and some 2100 additional mutants that are not necessarily independent . None of the mutants showed the absolute polar effect characteristic of insertion mutations or the reversion properties characteristic of insertions (low spontaneous reversion frequency and no reversion induction by chemical mutagens) . A few mutants, showing a high spontaneous reversion frequency, were screened physically . No insertion mutations were found . Thus insertion mutations appear to be rare in S . typhimurium, in strong contrast to E . coli and despite the possession in Salmonella of at least one type of insertion element (IS200) . These results suggest that in Salmonella transposition of the endogenous elements has been controlled . The transposition ability of the elements may have been reduced or favored target sites removed from the host genome. Mol Gen Genet, 1989 Apr, 216(2-3), 204 - 9 Transcriptional occlusion of transposon targets; Casadesus J et al.; In Salmonella typhimurium, insertion of transposons Tn5, Tn10 and bacteriophage Mu is inhibited by transcription of some target sequences . The transcription effects on Tn5 are large when the lac operon is a target but are limited to a slight effect on the hisG gene of the his operon . The Tn10 element shows target occlusion in both operons . Phage Mu has been shown previously to be inhibited for insertion into the lac operon . In the his operon Mu is only inhibited for insertion into the hisG gene . The variability of the inhibition effect from one sequence to another suggests site or regional specificity for transcription effects . Reducing the probability of insertion into transcribed sequences may be of selective importance to transposons since it reduces the risk of killing the host while maintaining the ability to transpose. Mutat Res, 1989 Apr, 211(2), 291 - 9 Modulation of mutagenesis involving precise excision of transposon Tn10; Hafner LM et al.; Precise excision of transposon Tn10 results in reversion of the Trp- phenotype to Trp+ in a trp-1014::Tn10 strain of Salmonella typhimurium, and also occurs at a markedly higher frequency in a strain carrying the temperature-sensitive polA7 allele . The frequency with which precise excision events occurs can be modified by the plating medium, results indicating that the great majority of mutants which arise on broth-supplemented or tryptophan-supplemented minimal media actually arise on the selective plating medium . Trp+ revertants (1000) arising from excision of Tn10 were purified by re-streaking for single colonies; none were found to retain the Tn10 encoded resistance to tetracycline . Yields of Trp+ revertants of the polA7 strain were consistently higher when glycerol rather than glucose was used as sole carbon source in the selective medium . Clean excision of Tn10 can also be increased by ultraviolet irradiation in (R) plasmid-free strains, and is further increased in strains carrying an N-group plasmid (R205, R46 or pKM101) . Ultraviolet-induced precise excision of Tn10 also occurs at a much enhanced frequency in a strain with a deletion through the uvrB gene; in this case, however, the addition of plasmid pKM101 leads to a decrease in yields of ultraviolet-induced precise excision events. Zhongguo Yi Xue Ke Xue Yuan Xue Bao, 1989 Apr, 11(2), 97 - 101 {Preliminary study on mutagenicity of MeIQ and extracts of fried fish and antimutagenicity of some dietary factors}; Liu XL; 2-amino-3,4-dimethylimidazo (4,5-f) quinoline (MeIQ) and extracts of fried fish showed a strong mutagenicity as reflected backward mutation in Salmonella typhimurium . Significant inhibitory effects on mutagenicity induced by MeIQ or extracts of fried fish were found by simultaneous treatment with extracts of fresh vegetables, fruits and especially green tea antioxidants . The results indicated that some mutagens and/or carcinogens might be produced during high temperature cooking of some animal meats . The frequent intake of fresh vegetables, fruits and green tea might be beneficial in the prevention of human cancer. Biochimie, 1989 Apr, 71(4), 477 - 89 L-Histidinol phosphate aminotransferase from Salmonella typhimurium . Kinetic behavior and sequence at the pyridoxal-P binding site; Hsu LC et al.; A coupled assay with alpha-hydroxyglutarate dehydrogenase was used to analyze the kinetic behavior of histidinol phosphate aminotransferase from Salmonella typhymurium . Data obtained from studies of initial velocity, inhibition by products or substrate analogues, isotope exchange rates, and the determination of the equilibrium constant were consistent only with a Ping-Pong Bi Bi mechanism . Variations in inhibition patterns by different substrate analogues indicate that the microenvironment about the pyridoxal phosphate and the pyridoxamine phosphate forms of histidinol phosphate amino-transferase are different, and favor the presence of one active site with partially overlapping substrate-binding subsites for these 2 forms of the enzyme . Histidinol phosphate aminotransferase also catalyzes decomposition of beta-chloro-L-alanine to pyruvate, NH3 and Cl-; no transamination of this substrate occurs and inactivation of the enzyme accompanies this reaction . After reduction of histidinol-P aminotransferase with {3H}NaBH4, carboxymethylation, and tryptic digestion, one major radioactive peptide absorbing at 325 nm was isolated . Its primary structure was determined to be TLSK*AFALAGLR, where K* is the P-pyridoxyllysine residue . Although this peptide is only 30-40% homologous with the corresponding segment reported for other transaminases, all of these peptides are similar in placement of an hydroxyamino acid residue three residues upstream from the lysine residue, and in the cluster of hydrophobic amino acid residues immediately following the lysine residue. Appl Environ Microbiol, 1989 Apr, 55(4), 832 - 6 Cell surface charge characteristics and their relationship to bacterial attachment to meat surfaces; Dickson JS et al.; Cell surface charge and hydrophobicity of Bacillus subtilis, Escherichia coli O157:H7, Listeria monocytogenes, Salmonella typhimurium, Serratia marcescens, Staphylococcus aureus, and Staphylococcus epidermidis were determined by hydrocarbon adherence, hydrophobic interaction, and electrostatic interaction chromatography . Surface charge and hydrophobicity were compared with the initial attachment values and rates of attachment of the bacteria to meat surfaces . There was a linear correlation between the relative negative charge on the bacterial cell surface and initial attachment to lean beef muscle (r2 = 0.885) and fat tissue (r2 = 0.777) . Hydrophobicity correlated well with attachment to fat tissue only . The relative hydrophobicity of each bacterium was dependent on the specific method of determination, with wide variations noted between methods. Mutat Res, 1989 Apr, 222(4), 403 - 7 Modifying role of dietary factors on the mutagenicity of aflatoxin B1: in vitro effect of sulphur-containing amino acids; Shetty TK et al.; Sulphur-containing amino acids including some derivatives have been tested for their effectiveness in suppressing the mutagenic activity of aflatoxin B1 in Salmonella typhimurium strains provided with a rat liver activation system . Cysteine and N-acetylcysteine have been found to be most effective in the 2 strains tested (TA100 and TA98) . Glutathione (oxidised and reduced forms) has shown partial activity, while cystine and methionine are found to be partially effective only in strain TA100 . Inhibition of mutagenicity may be due to interaction of these substances with microsomal enzymes resulting in interference with the formation of ultimate mutagenic species. Mutat Res, 1989 Apr, 222(4), 393 - 401 Modifying role of dietary factors on the mutagenicity of aflatoxin B1: in vitro effect of plant flavonoids; Francis AR et al.; Eighteen flavonoids have been tested for their ability to inhibit the mutagenicity of aflatoxin B1 (AFB1) towards strains TA100 and TA98 of Salmonella typhimurium provided with a rat liver activation system . These flavonoids belong to 5 different groups: flavone, isoflavone, flavanone, flavanol and flavonol, and many individual members are natural products present in edible portions of a variety of food plants . Several flavonoids exhibited significant inhibitory ability in both strains . Flavonols in general are more active in this regard, while flavanones show a strain-specific response . The flavanol group of compounds did not display any activity . Among the most effective flavonoids are kaempferol, morin, fisetin, biochanin A and the glycoside rutin, all of which exhibit a dose-dependent inhibition pattern . Kaempferol and rutin, in particular, show exceptional activity inasmuch as, on a molar basis, only a 10-fold excess dose of each can inhibit the mutagenic activity of AFB1 in strain TA98 by 50% . The action of flavonoids is possibly mediated through interaction with microsomal activating enzymes . Previous evidence from this laboratory about their inhibitory action on DNA-adduct formation and metabolic activation together with the present results suggests that certain flavonoids, notably polyhydroxylated flavonols, may have potential anticarcinogenic activity against AFB1. Mutat Res, 1989 Apr, 222(4), 343 - 50 Dimethylglycine and chemically related amines tested for mutagenicity under potential nitrosation conditions; Hoorn AJ; Dimethylglycine (DMG) and the chemically related amino acids glycine, sarcosine (monomethylglycine) and betaine (trimethylglycine) were tested in Salmonella typhimurium strain TA100 after treatment with sodium nitrite under acidic conditions using a modified Ames Salmonella/microsome assay as reported by Colman et al . (1980) . The increase in the number of revertants observed both with and without metabolic activation was also induced in the control mixtures without adding the amines . From the subsequent testing of the individual components of the mixtures, we concluded that non-consumed nitrite was responsible for the mutagenic responses observed in the different reaction mixtures, and not the amines themselves . There were no consistent indications of mutagenic activity of the DMG test mixture as compared to the control mixture which exhibited both consistent mutagenic activity and a toxic effect which was not increased by the addition of DMG . In fact, DMG seemed to decrease the toxicity of the control reaction solution to the Salmonella which was clearly observed at the higher doses . DMG cannot be considered mutagenic under the test conditions employed . The same can be said of the other amino acids as well. J Biol Chem, 1989 Mar 25, 264(9), 5006 - 14 Reconstitution of the histidine periplasmic transport system in membrane vesicles . Energy coupling and interaction between the binding protein and the membrane complex; Prossnitz E et al.; The periplasmic histidine transport system of Salmonella typhimurium has been reconstituted in isolated right-side-out membrane vesicles . The reconstituted system is entirely dependent on both the periplasmic protein, HisJ, and the membrane-bound complex, composed of proteins HisQ, HisM, and HisP . Transport is also dependent on the presence of ascorbate and phenazine methosulfate, which provide the energy for transport . Ascorbate oxidation generates a proton-motive-force, which allows ATP synthesis . ATP (or a cogenerated molecule) appears to be the immediate energy donor . Dissipation of the proton-motive-force or reduction of the level of ATP by a variety of treatments results in inhibition of transport . Vanadate inhibits transport, indicating that ATP utilization is necessary to energize transport . The interaction between liganded HisJ and the membrane complex has been measured directly: it displays Michaelis-Menten type kinetics, with a K1/2 of approximately 65 microM . The significance of this finding in terms of transport properties of whole cells is discussed. J Biol Chem, 1989 Mar 5, 264(7), 3998 - 4002 Reconstitution of periplasmic transport in inside-out membrane vesicles . Energization by ATP; Ames GF et al.; The periplasmic histidine permease of Salmonella typhimurium has been reconstituted in inside-out vesicles (IOV) of Escherichia coli by disrupting the cells with a French press in the presence of a high concentration of the periplasmic histidine-binding protein, HisJ . Efflux from IOV, which is equivalent to uptake in whole cells, is induced by ATP . The reconstituted system depends on the presence of the membrane-bound permease proteins, HisQ, HisM, and HisP, and does not function if reconstitution is performed in the presence of a mutant HisJ protein, HisJ5625, that can bind histidine normally but can't interact properly with the membrane complex . Efflux is not induced by the nonhydrolyzable ATP analog, adenyl-5'-yl imidodiphosphate, supporting the contention that ATP hydrolysis is necessary . 8-Azido ATP inactivates IOV, indicating that the ATP effect occurs through the HisP protein, which has previously been shown to be modified by 8-azido ATP (Hobson, A., Weatherwax, R., and Ames, G.F.-L . (1984) Proc . Natl . Acad . Sci . U . S . A . 81, 733-7337) . The estimated Km of the vesicles for ATP is about 200 microM . Vanadate, an inhibitor of phosphohydrolase enzymes, inhibits ATP-induced efflux . We conclude that ATP is likely to be the proximal energy source for periplasmic permeases. J Biol Chem, 1989 Mar 5, 264(7), 3794 - 8 In vitro use of monoclonal antibodies in Escherichia coli S-30 extracts to determine the RNA polymerase sigma subunit required by a promoter; Jovanovich SB et al.; RNA polymerase requires one of a family of sigma subunits for specific promoter recognition and initiation . We have developed an in vitro method to define the RNA polymerase sigma subunit required by a promoter . Mouse monoclonal antibodies specific for either Escherichia coli sigma 70 or sigma 32 or Salmonella typhimurium sigma 54 were added to an E . coli coupled transcription-translation S-30 extract programed with a DNA template containing the promoter of interest . Using the representative lacUV5, glnAP2, and rpoDHS promoters as controls, we found that monoclonal antibodies to a given sigma subunit strongly inhibited transcription from cognate promoters which utilized that sigma subunit, but had little effect on transcription from noncognate promoters which used other sigma subunits . Supplementation of the S-30 extract with purified sigma 70, sigma 54, or RNA polymerase sigma 32-holoenzyme stimulated expression from the cognate promoters and inhibited noncognate promoters . These two tests, addition of monoclonal antibodies and addition of sigma subunits, provide a rapid means of identifying whether the sigma subunit required by any promoter expressed in the S-30 extract is sigma 70, sigma 54, or sigma 32 . We suggest that this method may provide a systematic approach for identifying promoters which use as yet uncharacterized sigma subunits. Carcinogenesis, 1989 Mar, 10(3), 483 - 7 The mouse-skin carcinogenicity of a mutagenic fraction from beech wood dusts; Mohtashamipur E et al.; A life-time mouse-skin carcinogenicity assay was conducted using female NMRI mice to evaluate the possible direct carcinogenic activity of a mutagenic fraction isolated from beech wood dusts . The samples of untreated beech wood dusts were extracted with methanol at pH3 and were purified from the inhibitory compounds toxic to bacteria, using silica-gel column chromatography . The fraction obtained after passing through the column was tested for mutagenicity in the Ames assay employing Salmonella typhimurium TA100 in the presence of Aroclor-treated rat-liver-S9 . Using acetone as the vehicle, this mutagenic fraction was tested for carcinogenicity on an area of 1-1.5 cm shaved skin of mice on the lower back . The mice were treated with half of each dose, twice a week, for only 3 months . The total doses applied per week were 2.5, 5, 7.5 or 10 g equivalent dust/mouse . No substance was used as promoter . No statistically significant difference was found when the life spans of treated and untreated animals were compared . The observed carcinogenic effect was based on tumours and lesions found only on the site of application of the test material . Of 210 mice (effective number, 129) serving as the negative controls, three developed skin lesions but no tumours . Of 280 treated animals (effective number, 188) 34 developed different types of tumours and 20 had a uniform type of precancerous skin lesion . Of 34 tumours observed 21 were originated from the skin, 12 from the mammary glands beneath the site of application, and one was a lymphoma . Comparing the negative controls with the treated animals, the overall carcinogenic effect observed was dose-dependent and statistically significant . Excluding the mammary tumours and a lymphoma found beneath the site of treatment, the overall induction of skin tumours was still significant . However, the dose-dependent increase in the number of skin tumours alone was not statistically significant . These results suggest that beech wood dust contains mutagenic and carcinogenic constituent(s). Carcinogenesis, 1989 Mar, 10(3), 461 - 9 Comparison of the in vitro metabolisms and mutagenicities of dibenzo{a,c}anthracene, dibenzo{a,h}anthracene and dibenzo{a,j}anthracene: influence of norharman; Lecoq S et al.; The comparison of the behaviour of three dibenzoanthracene (DBA) isomers, dibenzo{a,c}anthracene (DB{a,c}A), dibenzo{a,h}anthracene (DB{a,h}A) and dibenzo{a,j}anthracene (DB{a,j}A), polycyclic aromatic hydrocarbons (PAHs), whose carcinogenicity varies from very potent to apparently inactive, has been carried out . Influence of norharman (NH; 9H-pyrido{3,4-b}indol) was investigated for mutagenicity (reversion of histidine prototrophy) on Salmonella typhimurium TA 100, using 3-methylcholanthrene (3-MC)-induced rat liver microsomes or S9 (post-mitochondrial fractions) . A correlation with its influence, on the in vitro metabolism of radiolabelled molecules by the same enzymatic systems, was carried out . NH enhances the mutagenicities of DB{a,c}A and DB{a,h}A which are very well known mutagenic and carcinogenic PAHs . Contrary to its two isomers, the mutagenic potency of DB{a,j}A, which is considered as a weak mutagen and not a carcinogen, is strongly inhibited by NH . The balance sheets of the in vitro metabolism by microsomal enzymes, where the conjugation is excluded, were reported with or without NH . In the presence of the latter, the amounts of remaining DBAs slightly decreased while the metabolites covalently bound to microsomal proteins strongly decreased and the amount of hydrophobic metabolites highly increased . At the same time, the HPLC elution profiles of the metabolism pathways of the three DBAs are found to be modified in a similar way by NH: some of the metabolites are highly enhanced, and for all three DBAs, a tetraol, not detectable in the absence of NH, emerges . The results are discussed with regard to possible effects of NH. Mutat Res, 1989 Mar, 222(3), 223 - 35 DNA adduct formation, metabolism, and morphological transforming activity of aceanthrylene in C3H10T1/2CL8 cells; Nesnow S et al.; Aceanthrylene (ACE), a cyclopenta-fused polycyclic aromatic hydrocarbon (CP-PAH) related to anthracene, has been studied for its ability to be metabolized, to form DNA adducts, and to morphologically transform C3H10T1/2CL8 mouse embryo fibroblasts in culture . Although ACE has been previously shown to be a strong mutagen in Salmonella typhimurium strains TA89 and TA100, it did not transform C3H10T1/2 cells (0.4-16 micrograms/ml) under 2 treatment protocols: treatment (for 24 h) 1 day after seeding the cells; treatment (for 24 h) 5 days after seeding the cells . Both protocols are effective in detecting the morphological transforming activity of PAH and CP-PAH and the latter protocol has been shown to be effective in detecting chemicals which are active in the first protocol only with the additional treatment of the cells with a tumor promoter . ACE is metabolized by C3H10T1/2 cells to ACE-1,2-dihydrodiol (the cyclopenta-ring dihydrodiol) at a rate of 450 pmoles ACE-1,2-dihydrodiol formed/h/10(6) cells . ACE-7,8-dihydrodiol and ACE-9,10-dihydrodiol, identified as major Aroclor-1254-induced rat liver microsomal metabolites from their UV, NMR, and mass spectral data, were not identified in incubations of C3H10T1/2 cells with ACE . ACE-DNA adducts in C3H10T1/2 cells were isolated, separated, identified, and quantitated using the 32P-postlabeling method . ACE forms 4 major adducts and each was identified as an ACE-1,2-oxide/2'-deoxyguanosine adduct . The level of adduction was 2.18 pmoles ACE adducts/mg DNA after a 24-h incubation of ACE (16 micrograms/ml) with C3H10T1/2 cells . ACE-DNA adduct persistence and repair were evaluated in C3H10T1/2 cells using a hydroxyurea block after ACE treatment . ACE-DNA adducts were not repaired under the conditions used in the morphological transformation studies . Thus, ACE provides an interesting example of a mutagenic PAH which is metabolized by C3H10T1/2 cells to active intermediates, forms relatively stable and persistent 2'-deoxyguanosine adducts in C3H10T1/2 cells, and yet induces no detectable morphological transforming activity under the experimental conditions used. Mutat Res, 1989 Mar, 222(3), 155 - 60 The release of mutagens from airborne particles in the presence of physiological fluids; van Houdt JJ et al.; Airborne particulates collected indoors in residences and outdoors were extracted by soxhlet extraction and sonication with methanol . In a comparative study in which mutagenic activity was evaluated in the Salmonella typhimurium reversion assay both soxhlet extraction and sonication proved to be suitable extraction methods . First, the residue, obtained by sonication of loaded filters with methanol followed by evaporation to dryness (tar), was sonicated with newborn calf serum and lung lavage fluid from pigs . All serum extracts of the tar were mutagenic to Salmonella typhimurium TA98, and contained direct- and indirect-acting mutagens . However, the mutagenic activity recovered by serum was only about half of the total mutagenic activity of the tar . The other part of the mutagenic activity remained in the tar . Lung lavage fluid was only able to remove 5-10% of direct-acting mutagens from the tar of all samples . About 20% of indirect-acting mutagens from indoor air were recovered in lung lavage fluid, while the lung lavage fluid extract from outdoor air did not show indirect mutagenic activity . Second, mutagenic activity recovered by direct sonication of the filters with physiological fluids was comparable with the recovery obtained by sonication of the tar . However, after sonication of the filter with lung lavage fluid hardly any mutagenic activity remained on the filter, whereas after sonication of the tar a clear mutagenic activity was observed in the non-soluble residue. Cancer Res, 1989 Mar 1, 49(5), 1187 - 92 Human and rat kidney cell metabolism of 2-acetylaminofluorene and benzo(a)pyrene; Rudo KM et al.; The metabolism and mutagenic activation of the model carcinogens benzo(a)pyrene {B(a)P} and 2-acetylaminofluorene (AAF) by human and rat kidney cells were measured . A slicing technique followed by enzyme digestion was utilized to obtain the kidney cells . Although levels of total metabolism of B(a)P by rat and human kidney cells were similar, analysis of specific metabolites of B(a)P indicated that species differences existed . Human kidney cells produced the organic-soluble metabolites B(a)P-9,10-diol, B(a)P-4,5-diol, B(a)P-7,8-diol, B(a)P-3,6-quinone, and B(a)P-9-phenol . Rat kidney cells produced organic-soluble B(a)P-pre-9,10-diols, B(a)P-9,10-diol, B(a)P-4,5-diol, and B(a)P-6,12-quinone . Both species produced sulfate and glucuronide conjugates of all products . For AAF, kidney cells from some human tissues produced up to four times the level of total metabolites compared to rat kidney cells . Organic-soluble metabolites were qualitatively similar between the species and consisted of 2-aminofluorene (AF), N-hydroxy-AAF and ring-hydroxylated products at the 1, 3, 5/9, 7, and 8 positions . Sulfate and glucuronide conjugates of these metabolites were also detected . Human interindividual variation with kidney cells was about 2.5-fold for total AAF metabolism and up to 6-fold for individual AAF metabolites . For B(a)P metabolism, human interindividual variation in total metabolism was low while for specific metabolites there was up to a 4-fold variation . Levels of AAF and AF cell-mediated Salmonella typhimurium mutagenesis were significantly higher with human cells as compared to rat kidney cells . It appears that the differences between human and rodent kidney cell metabolism of chemical carcinogens vary with the chemical class and understanding these differences will be necessary in the extrapolation of rodent carcinogenesis data to humans. Indian J Exp Biol, 1989 Mar, 27(3), 207 - 9 Effect of Emblica officinalis Gaertn . (Indian gooseberry) fruit extract on sodium azide and 4-nitro-o-phenylenediamine induced mutagenesis in Salmonella typhimurium; Grover IS et al.; Water, acetone and chloroform extracts of E . officinalis fruit reduced sodium azide and NPD induced his+ revertants significantly in TA100 and TA97 a strains respectively of S . typhimurium . The chloroform extract was less active as compared to water and acetone extracts . Autoclaving of water extract for 15 min did not reduce its activity . The enhanced inhibitory activity of the extracts on pre-incubation suggests the possibility of desmutagens in the extracts . Besides ascorbic acid, a constituent of the extract, the role of other antimutagenic factors in the extract cannot be ruled out. Biofactors, 1989 Mar, 2(1), 35 - 44 Biochemical and genetic analysis of Salmonella typhimurium and Escherichia coli mutants defective in specific incorporation of selenium into formate dehydrogenase and tRNAs; Stadtman TC et al.; Mutation of a single gene, referred to as selA1 in Salmonella typhimurium and as selD in Escherichia coli, results in the inability of these organisms to insert selenium specifically into the selenopolypeptides of formate dehydrogenase and into the 2-selenouridine residues of tRNAs . The mutation does not involve transport of selenite into the cell or reduction of selenite to selenide since both mutant strains synthesize selenocysteine and selenomethionine from added selenite and incorporate these selenoamino acids non-specifically into numerous proteins of the bacterial cells . Complementation of the mutation in S . typhimurium with the selD gene from E . coli indicates functional identity of the selA1 and selD genes . Although the selA1 gene maps at approximately 21 min on the S . typhimurium chromosome and the selD gene at approximately 38 min on the E . coli chromosome, only a single gene in wild-type S . typhimurium hybridized to the E . coli selD gene probe . Transformation of the mutant Salmonella strain with a plasmid bearing the E . coli selD gene restored formate dehydrogenase activity, 75Se incorporation into formate dehydrogenase seleno-polypeptides and {75Se}seleno-tRNA synthesis . Transformation with an additional plasmid carrying an E . coli formate dehydrogenase selenopolypeptide-lacZ gene fusion showed that the selD gene allowed readthrough of the UGA codon and synthesis of beta-galactosidase in the Salmonella mutant. Biokhimiia, 1989 Mar, 54(3), 434 - 9 {Effect of lipopolysaccharide toxin on lipid and protein composition of human serum low density lipoproteins}; Viktorov AV et al.; Complexes of lipopolysaccharide (LPS) B of Salmonella typhimurium with human low density lipoproteins (LDL) formed during in vitro coincubation via spontaneous incorporation of LPS (complex LDL-LPS) or through the incorporation stimulated by the serum protein fraction (LPS/LDL complex) were studied . The LPS/LDL complex was shown to maximally bind 0.24 mg of LPS per 1 mg of LDL protein, whereas the LDL-LPS complex contained only 0.07 mg of LPS per 1 mg of LDL protein . The observed incorporation of LPS into LDL particles was not possibly associated with a transfer of lipids or proteins from high density lipoproteins to LDL . The insertion of LPS was probably accompanied by the expulsion of a small portion of phosphatidylcholine molecules from the outer monolayer of LDL into the aqueous medium and by an increase in the phosphatidylethanolamine concentration in LDL . Simultaneously, the level of esterified cholesterol in the LPS/LDL complex decreased, and the concentrations of free cholesterol and triacylglycerols showed a rise . The level of free fatty acids in the LPS/LDL complex increased more than twofold compared with intact LDL . The enhancement of LPS incorporation did not result in the insertion of any serum proteins into LDL, in which apoB-100 remained the major apolipoprotein (ca . 90%); apoB-100 fragments made up to 5-7%, whereas apoE and apoC contained altogether ca . 3-5% . It is suggested that the LPS/LDL complex obtained can bind to three types of cell receptors, i.e., apoB/E receptors, LPS receptors and scavenger receptors of macrophages (monocytes); the increased level of free fatty acids in the LPS/LDL complex may accelerate its subsequent catabolism. Mol Gen Genet, 1989 Mar, 216(1), 164 - 9 DNA sequence of the metC gene and its flanking regions from Salmonella typhimurium LT2 and homology with the corresponding sequence of Escherichia coli; Park YM et al.; The DNA sequence of the Salmonella typhimurium metC gene and its flanking regions was determined . The metC gene contains an open reading frame of 1185 nucleotides encoding a polypeptide of 395 amino acids with a predicted molecular weight of 42,874 daltons . S1 nuclease mapping experiments located the transcription start site of the metC gene . The nucleotide sequence and the deduced amino acid sequence for the metC genes of S . typhimurium and Escherichia coli were compared . Although there are 279 nucleotide replacements, most do not change the amino acid sequence . Nucleotide sequence analysis of the flanking regions of the S . typhimurium metC gene shows that there is an open reading frame upstream and an open reading frame downstream of the gene . The existence of the divergently transcribed upstream open reading frame (designated ORF1) was confirmed by the construction of an ORF1-lacZ fusion . The transcription start site of ORF1 was determined by S1 nuclease mapping. Mutagenesis, 1989 Mar, 4(2), 126 - 32 A study of the heterogeneity of bacterial fluctuation-test data and the effects of auxotrophic-growth enhancement; Bosworth D et al.; Microtitre fluctuation tests using Salmonella typhimurium TA100 and TA98 and Escherichia coli WP2uvrApKM101 were performed to determine the heterogeneity of spontaneous mutagenicity data and how this affects interpretation of results . Assays were performed in the absence and presence of additional amino acids to simulate the effects of the auxotrophic growth enhancement characteristic of tests of complex biological mixtures . The results indicate that the heterogeneity of the data did not depart significantly from that expected from binomial theory and that two criteria must be satisfied in order to define a positive result: (i) a net increase which significantly exceeds the background mutation and which takes account of its heterogeneity; and (ii) a statistically significant dose response. Mutagenesis, 1989 Mar, 4(2), 115 - 25 Evaluation of the mutagenicity of azo dyes in Salmonella typhimurium: a study of structure-activity relationships; Shahin MM; In order to explore structure-activity relationships, 4,4'-diaminoazobenzene and four structurally related azo dyes were tested for their ability to induce gene mutations in Salmonella typhimurium strains TA1535, TA100, TA1537, TA1538, and TA98 . Only 4,4'-diaminoazobenzene and 4,4'-N(beta-hydroxyethylamino)azobenzene were found to be active in the two frameshift strains TA1538 and TA98 . Further tests were performed in strain TA98, both in the presence and in the absence of Aroclor 1254-induced rat or hamster liver S9 preparations . The amount of S9 used per plate was 50, 100, 150 or 300 microliters, which corresponds to 10, 20, 30 or 60% of S9 in S9 mix . 4,4'-Diaminoazobenzene was found to be mutagenic, and its mutagenicity depended on the percentage of S9 in S9 mix and the type of S9 fraction used . 4,4'-N-(beta-Hydroxyethylamino)azobenzene was less mutagenic than 4,4'-diaminoazobenzene, indicating a reduction in mutagenicity associated with the beta-hydroxyalkyl substituents . The other three azo dyes {4'-methyl-4-N,N-di(beta-hydroxyethylamino) azobenzene; 4'-amino-6-methyl-4-N,N-di(beta-hydroxyethylamino)azobenzene; and 4'-N(beta-hydroxyethyl-amino)4-N,N-di(beta-hydroxyethylamino)azobe nzene} were inactive, both in the presence and in the absence of the metabolic activation system . The use of the preincubation test did not alter the observed positive or negative response of these compounds . The importance of this finding is that the non-mutagenicity or decreased mutagenicity of these four compounds is predictable on the basis of their chemical structures . These azo dyes, like the non-mutagenic members of series of monocyclic aromatic amines, contain large substituents on one or both of the amino groups of the parent compound, in this case 4,4'-diaminoazobenzene . From our earlier data and the experiments discussed in this paper, we conclude that the study of structure--activity relationships can provide useful information for the prediction and interpretation of mutagenic responses. FEMS Microbiol Lett, 1989 Mar, 49(1), 49 - 54 Occurrence of Salmonella typhimurium virulence plasmid-specific sequences in different serovars of Salmonella; Korpela K et al.; We have subcloned the 96-kilobasepair (kb) virulence plasmid, pLT2, of Salmonella typhimurium line LT2 into 7 subfragments . Using these subclones as probes, 35 independent Salmonella isolates were tested for complementary DNA sequences Sequences homologous to pLT2 were present in 15 of the isolates . All of these contained sequences homologous to at least one specific probe representing 15 kb of pLT2 . The traT gene from pLT2 was absent in 6 of these 15 isolates . Three strains reported to be cured of the plasmid were shown to harbour some sequences with homology to the pLT2 plasmid . Seven isolates were shown to contain homologous sequences with pBR322 but not with the pLT2 plasmid. Eur J Biochem, 1989 Mar 1, 180(1), 23 - 32 Purification and characterization of a methionine-specific aminopeptidase from Salmonella typhimurium; Wingfield P et al.; An aminopeptidase specific for methionine (peptidase M) has been purified from wild-type and mutant Salmonella typhimurium strains . Recombinant peptidase M was also purified from Escherichia coli . These preparations were characterized with respect to their physicochemical properties using analytical ultracentrifugation, SDS/PAGE, isoelectric focusing, titration curve analysis, amino acid analysis, N-and C-terminal sequencing and various spectroscopic methods . Peptidase M activity is stimulated by Co2+, in agreement with previous studies using crude extracts of Salmonella . The purified preparations did not contain significant amounts of any metal . Enzymically important metal is loosely associated and lost during enzyme purification . Peptidase M was shown to contain seven free sulphydryl residues none of which are involved in either intra-or inter-molecular disulphide bonds . Most appear solvent-accessible as evidenced by their reactivity under native conditions . Limited modification of the sulphydryl residues with either iodoacetamide or 5,5'-dithiobis(2-nitrobenzoic acid) led to inactivation . Several cysteines were shown to be labelled to various degrees by peptide mapping of inactivated S-{14C}carboxymethylated protein . Whether cysteine modification affects enzymic activity directly (blocking an active site) or indirectly (by causing conformational change) remains to be established. Eur J Biochem, 1989 Mar 1, 180(1), 133 - 41 Identification and localization of the membrane-associated, ATP-binding subunit of the oligopeptide permease of Salmonella typhimurium; Gallagher MP et al.; The OppF protein, a component of the oligopeptide permease of Salmonella typhimurium, is an ATP-binding protein and is believed to couple ATP hydrolysis to the transport process . This protein is an example of a large family of closely related proteins which couple ATP to a variety of different biological processes . The oppF gene has been cloned and sequenced . In order to identify and characterize its protein product we overproduced the protein from the cloned gene . Anti-OppF antibodies were raised against a synthetic peptide . Using these antibodies as a probe we identified OppF in wild-type and overproducing strains . Protease accessibility studies showed the protein to be a peripheral membrane protein located on the cytoplasmic side of the inner membrane . These findings have general implications for the organization and function of this class of prokaryotic and eukaryotic transport system. Res Vet Sci, 1989 Mar, 46(2), 153 - 9 Relative importance of Salmonella-specific antibody isotypes in phagocytosis of Salmonella typhimurium by ovine mammary neutrophils; Mukkur TK et al.; The comparative opsonic efficiency of ovine salmonella-specific antibody isotypes was determined by measurement of specific phagocytic uptake of opsonised virulent Salmonella typhimurium by ovine mammary neutrophils . An in vitro phagocytosis assay revealed that IgM was superior to IgG2 in promoting the phagocytosis of opsonised virulent organisms . IgG1, on the other hand, was non-opsonic . Superiority of the IgM isotype over IgG2 as an opsonin was also evident in studies on the viability of opsonised S typhimurium upon phagocytosis . It was revealed that the percentage of organisms killed was appreciably greater when opsonisation was carried out with the IgM than with the IgG2 isotype, although after ingestion by neutrophils there was essentially no difference in the efficiency with which the ingested organisms were killed. Mutat Res, 1989 Mar, 225(3), 75 - 82 Mutagenicity of nitro- and amino-substituted phenazines in Salmonella typhimurium; Watanabe T et al.; The nitro- and amino-substituted phenazines were synthesized and assayed for their mutagenicity in Salmonella typhimurium strains TA98 and TA98NR . Of 7 tested nitrophenazines, 4 were mutagenic in the absence of a microsomal metabolic activation system (S9 mix) and were more mutagenic in TA98 than in TA98NR . The order of mutagenicity of nitrophenazines in TA98 is 1.7- less than 2- less than 2.8- less than 2.7-substituted phenazine . Of 7 tested amino derivatives, 4 exhibited mutagenic activity with S9 mix in TA98 . 1-Nitro-, 1-amino, 1.6-dinitro-, 1.9-dinitro-, 1.6-diamino- and 1.9-diamino-phenazine were not mutagenic . As regards the relationship between mutagenic potency and chemical structure of the phenazines, the results suggested that structural requirements favoring mutagenic activity were the presence of substituents at the 2 and/or 7 position . Furthermore, 2.7-disubstituted phenazines were extremely mutagenic, 2.7-dinitrophenazine and 2.7-diaminophenazine induced 36,450 and 12,110 rev./nmole, respectively . In the preliminary study, 2.7-diaminophenazine was identified by gas chromatography/mass spectrometry from the reaction mixture of m-phenylenediamine and hydrogen peroxide. Mutat Res, 1989 Mar, 222(3), 237 - 44 Genotoxicity and genotoxic enhancing effect of tetrandrine in Salmonella typhimurium; Whong WZ et al.; Tetrandrine has been used for the treatment of silicosis in China . The potential genotoxic and carcinogenic hazards of this drug were studied using the Salmonella/histidine reversion assay and the SOS/Umu test . The results show that tetrandrine was weakly mutagenic to Salmonella typhimurium TA98 with metabolic activation and did not induce SOS response . However, tetrandrine increased the mutagenic activity of benzo{alpha}pyrene, trinitrofluorenone (TNF), 2-aminoanthracene (2AA), diesel emission particles, airborne particles, and cigarette smoke condensate by more than 100%; the activity of aflatoxin B1 and fried beef was increased by over 75% . It also increased the 2AA and TNF-induced SOS response by more than 300% . These results indicated that tetrandrine was a weak promutagen inducing frameshift mutations and was a potent genotoxic enhancer . The mechanism for the genotoxic enhancement is not known . However, the fact that the increase in mutagenicity was noted only in TA98 and not in TA1538 suggested that the enhancement of genotoxicity by tetrandrine may result from an increase in error-prone DNA repair. Mutat Res, 1989 Mar, 222(3), 161 - 6 Influence of the Uvr repair system on the mutagenicity of antiparasitic drugs; Espinosa-Aguirre JJ et al.; One amebicide (chloroquine diphosphate) and 2 anthelmintic compounds (niclosamide and pyrvinium pamoate) were found to be mutagenic for Salmonella typhimurium TA1537, TA1538, TA100 and TA98 Uvr- strains respectively . Drugs tested on homologous Uvr+ strains (TA1977, TA1978, UTH8414 and UTH8413) showed decreased mutagenic activity of the compounds . This indicates that premutational damage induced by the drugs was totally or partially repaired . Furthermore, results obtained in the present study suggest that niclosamide and pyrvinium pamoate induce premutational lesions by adduct formation, and that chloroquine diphosphate, known as an intercalating agent, behaves as an adduct-forming compound as regards its effects on Uvr- and Uvr+ S . typhimurium strains. Mutat Res, 1989 Mar, 222(3), 141 - 8 Antimutagenicity of some citrus fruits in Salmonella typhimurium; Bala S et al.; The antimutagenic effect of 10 citrus fruit juices was observed against the mutagenicity of N-nitro-o-phenylenediamine (NPD) in TA97a and sodium azide in TA100 tester strains of Salmonella typhimurium using the Ames test . It was noticed that the juices of all these fruits reduced significantly the NPD and sodium azide induced revertant colonies . The inhibitory activity was enhanced if the mutagen and juice were co-incubated for about 30 min at 37 degrees C prior to performing the mutagenicity assay . Dilution with distilled water led to the reduction in the inhibitory activity . The antimutagenic activity of synthetic ascorbic acid or citric acid or combined ascorbic acid and citric acid was also seen . But the results with fruit juices tempted us to believe that in addition to ascorbic acid and citric acid, the presence of other factor(s) possessing antimutagenic properties cannot be ruled out. Biochim Biophys Acta, 1989 Mar 1, 1007(2), 196 - 202 Immunochemical identification of a tRNA-independent cytokinin-like compound in Salmonella typhimurium; Blum PH et al.; Chemical and immunological characterization of Salmonella typhimurium cell extracts indicates that this organism produces a molecule which closely resembles the plant growth regulator, cytokinin . Alcohol-soluble cationic ultraviolet-absorbing material was fractionated by reverse-phase HPLC using gradient conditions optimized previously for modified nucleoside separation . A single hydrophobic compound was identified in the cytokinin region of the gradient, and limited quantities of the compound were prepared by HPLC fractionation of crude extracts . The compound demonstrated significant activity in a radioimmunoassay for cytokinins which detects N6-isopentenylated adenine derivatives . Boronate affinity chromatography indicated the compound is likely to be ribosylated and therefore a nucleoside . These and other tests indicate the compound has the most notable structural characteristics of a cytokinin . Spectral analysis and chromatographic comparison with cytokinin standards indicate the compound also has some unique structural features . Presence of the compound in extracts of an S . typhimurium mutant blocked for synthesis of tRNA-derived cytokinins excluded tRNA as a source for the compound and implicates existence of a tRNA-independent pathway for cytokinin biosynthesis in this bacterial species. Infect Immun, 1989 Mar, 57(3), 850 - 7 Sequence analysis of rsk, a portion of the 95-kilobase plasmid of Salmonella typhimurium associated with resistance to the bactericidal activity of serum; Vandenbosch JL et al.; Increased sensitivity to killing by human serum complement occurs in Salmonella typhimurium strains in which the 95-kilobase virulence plasmid is integrated into the chromosome . This phenotypic change appears to be due to alterations in plasmid gene expression and is reversed by the presence of an autonomous plasmid bearing a cloned region of the virulence plasmid . Accordingly, this region has been termed rsk for reduced serum killing . Sequence analysis of the region reveals that rsk is composed of a series of direct 10-base-pair (bp) repeats with a 21-nucleotide periodicity . Two adjacent repeats are identical, but increasing loss of conservation is apparent with increased distance both 5' and 3' of these highly conserved 10-mers . The smallest isolated sequence which restores the serum-resistant phenotype is only 66 bp long and contains the two identical 10-mers and one degenerate 10-mer (8 of 10 bp conserved) 3' of these . The minimal rsk region of 66 bp does not appear to contain a coding sequence, or a promoter, for a structural gene . It is proposed that the minimal rsk is an isolated regulatory site involved in the regulation of the serum resistance of S . typhimurium . Integration of the 95-kilobase plasmid disrupts the normal regulation of virulence plasmid genes, resulting in an increase in the killing of the bacteria by complement activated by the classical pathway . The introduction of the minimal rsk on a multiple-copy plasmid restores resistance to serum killing, possibly through the titration of a trans-acting regulatory factor. Kanagawa Shigaku, 1989 Mar, 23(4), 568 - 86 {The roles of macrophage on the mechanism of development of periapical lesion . The response of macrophage stimulated with bacteria isolated from infected root canals}; Tominaga N; It has been proposed that bacteria in infected root canals are most important agents to pathogenesis of the periapical lesion . The aim of the present study was to examine the roles of macrophage on the mechanism of development of periapical lesion . Therefore the influences of bacteria isolated from infected root canals to macrophage functions and the effects of products from macrophage stimulated with bacterial components to periodontal tissue were investigated . In this study, sonic extracts prepared from Bacteroides buccae predominantly isolated from root canals were tested for its capacity of induction of chemotaxis and production of prostaglandin E2 and collagenase from human peripheral monocyte . Furthermore prostaglandin E2, collagenase production and alkaline phosphatase activity of fibroblasts from human periodontal ligament (HPLF), pulp (HPF) and gingiva (Gin 1) stimulated with macrophage conditioned medium (MCM) stimulated with B . buccae sonic extracts were examined . The results obtained were as follows . The sonic extract of B . buccae showed capacity to induce macrophage chemotaxis directly and by activation of serum complement, and the serum activated with sonic extract of B . buccae was more active than the serum activated with LPS of Salmonella typhimurium . Prostaglandin E2 production of macrophage was increased when the cells were stimulated by sonic extracts of B . buccae, but collagenase activity . toas not increased . MCM stimulated with sonic extracts of B . buccae fot 48 hours strongly induced PGE2 and collagenase production from HPLF and HPF, at the same time sonic extract showed the similar capacity of induction of the PGE2 production of MCM . But, HPF stimulated with sonic extract showed the low activity of induction of the PGE2 production . On the other hand, Gin 1 cell produced a few amount of the PGE2 when it was stimulated with MCM, but not produced collagenase . Alkaline phosphatase activity of HPLF and HPF had been inhibited by addition of MCM stimulated with B . buccae sonic extract. Kanagawa Shigaku, 1989 Mar, 23(4), 451 - 68 {Bacteriological and immunological studies on the mechanism of development of periapical lesion . Immunobiological activities and localization in periapical lesion of the cellular components from Bacteroides buccae}; Tani N; It has been strongly suggested that the periapical lesion develop as a result of immunopathological response to continuous antigenic stimulation . Bacteria from root canal systems might be most important pathogenesis capable of inducing immunological reactions in periapical tissue . The purpose of this study, therefore, was clarify the immunological potentials of Bacteroides buccae (B . buccae) which was frequently isolated from root canals with chronic periapical lesion . Biological activities of B . buccae cellular components, such as lipopolysaccharides (LPS) and cellular protein were investigated on the enhancement of monocytes migration induction of interleukin 1 (IL-1) production, mitogenicity and polyclonal B cell activation . The localization of immunocompetent cells and B . buccae in human chronic periapical lesions were examined by biotin-avidin-horseradish peroxidase method, and peroxidase antiperoxidase methods using monoclonal antibodies . Following results were obtained . 1 . On the lymulus lysafe clotting activity and Shwarzman activity of B . buccae LPS were about half of Salmonella typhimurium (S . typhimurium) . 2 . Both LPS and 38K protein preparations from B . buccae enhanced the activity of human peripheral monocytes migration and induced IL-1 production . 3 . It was found that mitogenicity of LPS from B . buccae on splenocytes of BALB/c and BALB/c nu/nu mice was weaker than that of 38K protein, however mitogenicity on thymocytes were not shown in both preparations . 4 . The polyclonal B cell activation on splenocytes of BALB/c nu/nu mice by B . buccae were remarkably induced by 38K protein, but LPS showed less activity elicit than 38K protein . 5 . It might be suggested that the both LPS and 38K protein of B . buccae may depend on the activities of macrophage and lymphocytes . 6 . Antigenic substance of B . buccae were found most commonly engulfed materials within macrophage and intercellular space in connective tissue . 7 . Dense accumulation of T and B lymphocytes were observed gathering around the phagocytic macrophage (foam cell), the number of B lymphocytes around the macrophage was greater than that of T lymphocytes . 8 . These findings indicated that both LPS and 38K protein from B . buccae have a wide regulation function of immunobiologic responses . Therefore, it was suggested that both LPS and 38K protein from B . buccae may play significant roles in the pathogenesis of periapical lesion. FEMS Microbiol Immunol, 1989 Mar, 1(4), 229 - 35 Oral vaccination of rats with live avirulent Salmonella derivatives expressing adhesive fimbrial antigens of uropathogenic Escherichia coli; Schmidt G et al.; The avirulent Salmonella typhimurium F885 was transformed with a plasmid carrying the cloned S fimbriae genes of a uropathogenic Escherichia coli . The resulting transformant (F885-1) produced efficiently E . coli S fimbriae and was used for live oral vaccination of rats . For comparison rats were immunized subcutaneously with isolated S fimbriae . Both routes of vaccination resulted in a significant IgG antibody response to S fimbriae . In addition live oral vaccination induced a serum IgA response against S fimbriae . After transurethral infection of rats with a S fimbriae producing E . coli a 10-fold reduction of bacterial counts in the kidney was observed in rats orally vaccinated with F885-1 as compared to unvaccinated controls . This study suggests that the avirulent Salmonella F885 may be used as a fimbrial antigen carrier for oral vaccination against renal infections. Mutagenesis, 1989 Mar, 4(2), 90 - 4 Studies of error-prone DNA repair in Escherichia coli K-12 and Ames Salmonella typhimurium strains using a model alkylating agent; Little CA et al.; 4-Acetoxy-3-acetoxymethyl acetophenone (AAMAP) is mutagenic in Ames Salmonella typhimurium tester strains TA100 and TA98, which carry plasmid pKM101, but not in the isogenic plasmid-less strains TA1535 and TA1538 . Similarly, no AAMAP-induced reversion of the his-4 allele is detectable in Escherichia coli K-12 umuC strains in the absence of the plasmid, even when the strains are treated with ethylene-diaminetetraacetate to increase permeability, or when the uvrB allele is introduced to increase error-prone DNA repair . AAMAP is, however, mutagenic in umuC+ strains or in umuC strains in which plasmid pKM101 has been introduced, suggesting that the plasmid-encoded MucAB or the chromosomally determined UmuDC proteins are required for mutagenesis . Mutation frequencies are higher in E . coli umuC (pKM101) strains, which resemble Ames tester strains of S . typhimurium, than in E . coli umuC+ or even umuC+ (pKM101) strains . Therefore, providing that the recommended pKM101-containing tester strains are used, the apparent absence of Umu-like protein activity in S . typhimurium may actually increase the sensitivity of the Ames test for the detection of mutagens that require error-prone DNA repair for activity. Immunopharmacology, 1989 Mar-Apr, 17(2), 107 - 18 Murine macrophage activation with resorcyclic acid lactones (RALs): comparison with diethylstilbestrol and 17 beta-estradiol; Edwards CK 3rd et al.; Zearalane, a resorcyclic acid lactone (RAL) derivative, activates murine macrophages (M phi) in vivo and in vitro . Mouse M phi incubated in vitro with different concentrations of zearalane released superoxide anion (O2-) on stimulation with either opsonized zymosan (Op-zym), phorbol myristate acetate (PMA), or Salmonella typhimurium . The levels of O2- released were similar to those released from M phi incubated in vitro with supernatants enriched in macrophage-activating factors from concanavalin A-stimulated mouse spleen cells . In contrast, 17 beta-estradiol (E2) or diethylstilbestrol (DES) induced little or no enhancement of O2- release . Zearalane, dideoxyzearalane, DES and E2 were tested for induction of host resistance to S . typhimurium infection in mice . Treatment of mice with zearalane (9 mg/kg) resulted in at least 65% survival 4 days post-infection, compared to 10% survival of mice with vehicle alone, DES, or E2 . Peritoneal and alveolar M phi from the zearalane-treated mice released up to six times as much O2- on stimulation with Op-zym as M phi from the other treatment groups . M phi activation was observed for up to 7 days after intraperitoneal or subcutaneous administration of zearalane in either aqueous or organic vehicles . These results suggest that zearalane may enhance resistance to infection by increasing bactericidal activity due to increased release of toxic oxygen radicals by M phi and mononuclear phagocytes . These effects differ from the immunosuppressive effects reported for DES and E2. Proc Natl Acad Sci U S A, 1989 Mar, 86(6), 1949 - 53 A region of a cyanobacterial genome required for sulfate transport; Green LS et al.; Using the cysA locus of Salmonella typhimurium as a heterologous probe, we have cloned a region of the Anacystis nidulans R2 (Synechococcus PCC 7942) genome involved in sulfate assimilation . The 8.3-kilobase-pair region encodes at least five transcripts that cannot be detected unless the cells are deprived of sulfur . One of the genes in this region has been sequenced, and the protein that it encodes is homologous to a polypeptide component of other permease systems of Escherichia coli and Salmonella . Insertional inactivation of the putative sulfate permease gene, designated cysA, as well as of other genes within this region, results in cysteine auxotrophy, reduced sulfate uptake, and altered expression of soluble and cytoplasmic-membrane polypeptides associated with sulfur starvation. J Periodontal Res, 1989 Mar, 24(2), 88 - 95 LPS-elicited secretory responses in monocytes: altered release of PGE2 but not IL-1 beta in patients with adult periodontitis; Garrison SW et al.; Lipopolysaccharide responsiveness in human subjects was assessed through the examination of LPS-stimulated PGE2 and IL-1 beta release from counterflow isolated monocytes from patients with varying levels of periodontal destruction . This study was performed in order to investigate a possible relationship between LPS-mediated secretory responses in monocytes and susceptibility to periodontal destruction in humans . Subjects were chosen based on apparent resistance or susceptibility to disease as measured by little or no periodontal destruction versus generalized severe destruction, respectively . Because IFN-gamma can influence LPS-stimulated responses, the effect of IFN-gamma on the LPS-stimulated release of PGE2 and IL-1 beta was also assessed . Peripheral blood monocytes were separated by counterflow centrifugation and cultured (10(6)/ml/well) with control medium or medium containing LPS from Bacteroides gingivalis, B . intermedius, Actinobacillus actinomycetemcomitans, or Salmonella typhimurium, with or without 10 Units/ml recombinant IFN-gamma . Media were exchanged at 24 and 48 hours and culture supernatants assayed for both PGE2 and IL-1 beta by RIA . Patients classified as Susceptible to periodontitis demonstrated 2- to 3-fold greater PGE2 release than Resistant patients . This difference was observed with all LPS preparations over both the 0-24 hour and 24-48 h culture periods . IL-1 beta release, however, was not significantly different between patient groups . IFN-gamma did not affect the LPS-stimulated release of PGE2 but significantly enhanced the release of IL-1 beta . The IFN-gamma effects were similar for both patient groups . These findings indicate that LPS-stimulated PGE2 release from peripheral blood monocytes may correlate with susceptibility to periodontitis in human subjects. Chem Res Toxicol, 1989 Mar-Apr, 2(2), 114 - 2 Comparison of rates of enzymatic oxidation of aflatoxin B1, aflatoxin G1, and sterigmatocystin and activities of the epoxides in forming guanyl-N7 adducts and inducing different genetic responses; Baertschi SW et al.; The genotoxicity of the dihydrofurans aflatoxin B1 (AFB1), aflatoxin G1 (AFG1), and sterigmatocystin (STG) was examined in a bacterial system in which the induction of SOS repair is monitored with the umuC gene linked to a lacZ reporter gene in plasmid pSK1002 . Human liver microsomal cytochrome P-450NF oxidized the dihydrofurans (in the presence of calf thymus DNA) to give guanyl-N7 adducts in the order AFB1 greater than STG greater than AFG1 . The order of the umu response seen was STG greater than AFB1 greater than AFG1, when either the dihydrofurans were activated enzymatically or the synthetic epoxides of the dihydrofurans were added directly to the bacteria . Thus, the umu response per molecule of guanyl-N7 DNA adduct follows the order STG greater than AFB1 greater than AFG1 . A similar pattern has been reported in the literature for Salmonella typhimurium base substitution dependent his reversions, but the pattern AFB1 greater than STG greater than AFG1 has been found for bacterial frame-shift-dependent mutagenesis and hepatocarcinogenesis . The guanyl-N7 adduct derived from AFG1 has considerably less of all of these biological activities per molecule . Neither guanine imidazole ring opening nor apurinic site formation appears to be a factor involved in the differential biological responses seen with the three guanyl-N7 adducts . These findings indicate that these structurally related guanyl-N7 DNA adducts have intrinsic differences which give rise to divergent biological responses. Mutat Res, 1989 Mar, 211(1), 139 - 45 Effects of prototypic PCBs on benzo{a}pyrene mutagenic activity related to vitamin A intake; Grolier P et al.; The effects of vitamin A dietary intake (2 and 20 IU */g of food) on the mutagenic activity of benzo{a}pyrene (B(a)P) toward Salmonella typhimurium (TA98) were studied either in control rats or in animals treated by the PCB congeners 2,4,5,2',4',5'-hexachlorobiphenyl {2,4,5)2Cl) and 3,4,3',4'-tetrachlorobiphenyl {3,4)2Cl) . (3,4)2Cl (a planar compound) strongly increased B(a)P monooxygenase (B(a)PMO) activity and glutathione transferase, (2,4,5)2Cl (a non-planar PCB) was a strong inducer of epoxide hydrolase and a weak inducer of B(a)PMO . Enzyme induction was not modified by changes in vitamin A dietary intake . A higher mutagenic effect was observed in the (3,4)2Cl group than in the (2,4,5)2Cl one . This could be related to the specific form of cytochrome P-450 induced by (3,4)2Cl . In the untreated animals, the activation of B(a)P was higher in the 2-IU group than in the 20-IU one . Conversely, in PCB-treated rats the mutagenic activity of B(a)P was higher in the 20-IU group than in the 2-IU one . PCB induction increased the liver content of vitamin C in both the 2-IU and the 20-IU groups but only increased the glutathione levels in the 2-IU groups . This suggests that glutathione content in cellular fractions may be one of the determining parameters for the mutagenic activity of B(a)P. Clin Exp Immunol, 1989 Mar, 75(3), 365 - 70 Response of synovial fluid T cell clones to Yersinia enterocolitica antigens in patients with reactive Yersinia arthritis; Hermann E et al.; From synovial fluids of two patients with reactive arthritis following Yersinia enterocolitica infection, T lymphocyte clones were obtained that showed proliferative responses to Y . enterocolitica . The responses required autologous T-cell-depleted peripheral blood mononuclear cells as antigen presenting cells . Three clones were studied in detail; two of them showed a marked and specific response to Yersinia antigens alone, the other one recognized both Yersinia and Salmonella typhimurium antigens . The antigen-specific proliferation of the clones could be completely blocked by monoclonal antibodies to HLA-DR . These experiments show that synovial T lymphocytes presumably involved in the in situ immune response to microbial antigens triggering reactive arthritis can be cloned directly from the site of inflammation. Science, 1989 Feb 24, 243(4894 Pt 1), 1059 - 62 A Salmonella locus that controls resistance to microbicidal proteins from phagocytic cells; Fields PI et al.; Facultative intracellular pathogens pose an important health problem because they circumvent a primary defense mechanism of the host: killing and degradation by professional phagocytic cells . A gene of the intracellular pathogen Salmonella typhimurium that is required for virulence and intracellular survival was identified and shown to have a role in resistance to defensins and possibly to other microbicidal mechanisms of the phagocyte . This gene may prove to be a regulatory element in the expression of virulence functions. Nature, 1989 Feb 23, 337(6209), 745 - 9 Three-dimensional structure of CheY, the response regulator of bacterial chemotaxis; Stock AM et al.; Homologies among bacterial signal transduction proteins suggest that a common mechanism mediates processes such as chemotaxis, osmoregulation, sporulation, virulence, and responses to nitrogen, phosphorous and oxygen deprivation . A common kinase-mediated phosphotransfer reaction has recently been identified in chemotaxis, nitrogen regulation, and osmoregulation . In chemotaxis, the CheA kinase passes a phosphoryl group to the cytoplasmic protein CheY, which functions as a phosphorylation-activated switch that interacts with flagellar components to regulate motility . We report here the X-ray crystal structure of the Salmonella typhimurium CheY protein . The determination of the structure was facilitated by the use of site-specific mutagenesis to engineer heavy-atom binding sites . CheY is a single-domain protein composed of a doubly wound five-stranded parallel beta-sheet . The phosphoacceptor site in CheY is probably a cluster of aspartic-acid side chains near the C-terminal edge of the beta-sheet . The pattern of sequence similarity of CheY with components of other regulatory systems can be interpreted in the light of the CheY structure and supports the view that this family of proteins have a common structural motif and active site. Biochemistry, 1989 Feb 21, 28(4), 1814 - 9 Relationship between guanosine tetraphosphate and accuracy of translation in Salmonella typhimurium; Negre D et al.; In bacteria a high level of mistranslation is observed in amino acid starved rel-, but not rel+, strains, and mistranslation can be studied qualitatively by means of "stuttering" experiments in two-dimensional protein gels . It has been suggested that the low level of mistranslation that occurs in rel+ strains is assured by guanosine 5'-diphosphate 3'-diphosphate (ppGpp), a nucleotide whose intracellular concentration greatly increases in rel+ cells under amino acid starvation . In the present study the relationship between level of ppGpp and mistranslation was analyzed by performing stuttering experiments in amino acid starved bacteria that contained either high or low levels of ppGpp . Three strains of Salmonella typhimurium were used in these experiments: a relA+ hisT+ strain (TA997), a relA+ hisT strain (TA1001), and a relA hisT strain (PD2) . These strains were first characterized with respect to macromolecular syntheses and ppGpp levels under exponential growth and under amino acid starvation . Both rel+ strains exhibited stringent control over RNA synthesis . ppGpp accumulated to high levels when TA997 was starved for either of three amino acids . Starvation of TA1001 for histidine did not cause accumulation of ppGpp, whereas starvation for lysine and arginine produced high levels of ppGpp . Extracts from the three strains, obtained either under exponential growth or under amino acid starvation, were then subjected to two-dimensional electrophoretic anaylsis: mistranslation was observed whenever ppGpp was absent . In particular, starvation of TA1001 for histidine resulted in high mistranslation frequencies, while under lysine and arginine starvation mistranslation was undetectable, regardless of whether the cells were rel+ or rel-.(ABSTRACT TRUNCATED AT 250 WORDS) Arch Biochem Biophys, 1989 Feb 15, 269(1), 25 - 31 Dichlorobenzidine-DNA binding catalyzed by peroxidative activation in Salmonella typhimurium; DeBruin LS et al.; Peroxidative oxidation of dichlorobenzidine in vitro results in covalent binding to exogenous DNA . In a modified Ames assay, mutagenicity is observed in S . typhimurium strain TA98 following the incubation of dichlorobenzidine, bacteria, and hydrogen peroxide . In this paper, we demonstrate that {14C}dichlorobenzidine becomes covalently bound to S . typhimurium macromolecules, including DNA, when exogenous hydrogen peroxide is supplied . We compared the levels of binding in a pair of otherwise isogenic strains with wild-type (oxyR+) versus constitutive (oxyR1) expression of the hydrogen peroxide stress-induced regulon . Binding was approximately twofold higher in TA4124 (oxyR1) than in TA4123 (oxyR+) . Bacterial hydroperoxidases may catalyze the activation of dichlorobenzidine to mutagenic and DNA binding species in this system. Cancer Res, 1989 Feb 15, 49(4), 853 - 6 Prostaglandin H synthase-dependent mutagenic activation of benzidine in a Salmonella typhimurium Ames tester strain possessing elevated N-acetyltransferase levels; Josephy PD et al.; Watanabe and colleagues (Biochem . Biophys . Res . Commun . 147: 974-979, 1987) have constructed plasmid-containing derivatives of Salmonella typhimurium Ames tester strain TA1538 with high levels of acetyltransferase activities . In this paper, we describe the mutagenic response of one of these strains, TA1538/1,8-DNP6 (pYG 121), to the bladder carcinogen benzidine and other arylamines . Strain TA1538/1,8-DNP6 (pYG 121) was far more sensitive to benzidine than any previous tester strain, following metabolism of the aromatic amine by hamster hepatic S9, ram seminal vesicle microsomal preparation (RSVM), or purified prostaglandin synthase . Therefore, bacterial acetyltransferase-dependent metabolism of a proximate mutagen is implicated in each of these systems . The mechanism of RSVM-dependent activation of benzidine was examined further . The arachidonic acid-independence and indomethacin insensitivity previously noted with strain TA98 were also observed with the new tester strain . We confirmed that prostaglandin H synthase is the enzyme activity responsible for activation of benzidine by RSVM . Purified prostaglandin H synthase holoenzyme, or apoenzyme reconstituted with heme, supported benzidine activation . However, apoenzyme reconstituted with manganese protoporphyrin IX, which yields enzyme having cyclooxygenase activity but not peroxidase activity, was inactive . Addition of catalase inhibited, and addition of exogenous hydrogen peroxide increased, RSVM-mediated benzidine mutagenicity . We propose that hydrogen peroxide released by the tester strain bacteria (rather than arachidonic acid-derived peroxide) is the oxidizing agent which supports prostaglandin H synthase peroxidase activity in Ames test systems. J Mol Biol, 1989 Feb 5, 205(3), 519 - 28 Image reconstruction of the flagellar basal body of Salmonella typhimurium; Stallmeyer MJ et al.; The basal body is thought to be a part of the rotary motor of the bacterial flagellum . It consists of a central rod coaxial with a set of four rings, which are associated with the cell envelope . We used single-particle averaging methods to analyze images of negatively stained basal bodies of Salmonella typhimurium . Several averages were computed, so that the reliability of features could be assessed . We carried out the same analysis on electron micrographs of isolated, negatively stained L-P rings . In order to interpret the averages in terms of a three-dimensional structure, we carried out image reconstruction on them . The resulting three-dimensional map corresponds to the cylindrically averaged structure of the basal body . To show that the reconstruction procedure is legitimate, we demonstrate it on model data . The results of the modelling show that features very near to the axis of the reconstruction are not reliable but that broader, off-axis features are represented faithfully . The L ring is L-shaped, with the long arm of the L parallel to the axis of the rod, and the short arm pointing away from the rod . The P ring, on the other hand, appears to be a ring or disk . The position of the L-P ring complex on the rod seems to vary somewhat, consistent with its putative role as a bushing . The cross-sectional shape of the S ring is that of a frustum rather than a disk . The M ring, which is oval in cross section, sits atop the S ring, making contact with it at an outer radius . The S ring appears to make contact with the rod, whereas the M ring does not . This situation, if true, is difficult to reconcile with the common notion that the S ring is stationary and the M ring rotates . It seems more likely that the S ring and rod rotate as a unit. J Natl Cancer Inst, 1989 Feb 1, 81(3), 223 - 7 Selective mutagenic activation by cytochrome P3-450 of carcinogenic arylamines found in foods; Snyderwine EG et al.; Heterocyclic arylamines found in cooked foods including fish and beef are potent mutagens and carcinogens . The purpose of this investigation was to determine the specificity of cytochromes P1-450 and P3-450 toward the metabolic activation of these arylamines . We used a novel mutagenicity test system which combined human cells expressing either recombinant cytochrome P1-450 or P3-450 with Salmonella typhimurium to score mutants . Cytochrome P3-450, a single isoform of the cytochrome P-450 supergene family, bioactivated these food mutagens . Cytochrome P1-450 showed little or no activation of these arylamines but was the isoform predominantly responsible for the activation of the aromatic hydrocarbon benzo{a}pyrene-7,8-diol . This assay system should serve to define the specificities of individual cytochromes P-450 in the metabolic activation of carcinogens. Acta Ophthalmol (Copenh), 1989 Feb, 67(1), 69 - 74 Early morphological changes of intracellular bacteria in Salmonella typhimurium infection of the guinea pig conjunctival epithelium; Latkovic S et al.; Conjunctival epithelium of the guinea pig was incubated with a virulent strain of Salmonella typhimurium 395 MS for 1 h . Intracellular bacteria were observed in superficial and intermediate cell layers, but not in basal cells . The majority of the bacteria were located within primary or secondary phagosomes; a few were seen free in the cytoplasm . A number of intraphagosomal bacteria showed morphological signs of degradation . Ultrastructurally, the initial phases of Salmonella typhimurium infection of the guinea pig conjunctival epithelium appear to be consistent with endocytic uptake of bacteria by the epithelial cells, followed by their degradation in secondary phagosomes . The conjunctival epithelial cells seem able to inactivate a certain number of virulent bacteria and thus, to a degree, to control the infection in its early phase with defence mechanisms pertaining to the cells themselves, without support from the professional phagocytic cells. Antimicrob Agents Chemother, 1989 Feb, 33(2), 192 - 7 Escherichia coli susceptible to glycopeptide antibiotics; Shlaes DM et al.; Mutants of Escherichia coli susceptible to vancomycin were isolated after mutagenesis with nitrosoguanidine . One such mutant was studied extensively . Multiple regression analysis of the relationship between physical properties of 20 glycopeptides and their in vitro activities against the vancomycin-susceptible mutant revealed a significant correlation with molecular mass (P = 0.007) . pI, hydrophobicity, and affinity of the glycopeptide for the pentapeptide target were not as important for activity . This suggested that a block of access of the antibiotic to its target could be the major factor determining activity . Outer membrane proteins of the vancomycin-susceptible mutant, resistant parent, and revertant strains appeared normal . The mutant exhibited increased susceptibility to both erythromycin and fusidic acid which was lost in single-step revertants to vancomycin resistance . Polymyxin B nonapeptide was synergistic with erythromycin and fusidic acid against the parent and revertant but not against the susceptible mutant . Analysis of the susceptibilities of control strains of E . coli and Salmonella typhimurium with known defects in lipopolysaccharide (LPS) synthesis revealed that core LPS mutants (Re chemotype) were phenotypically similar to the E . coli mutant under study . However, the LPS core of the mutant migrated slightly less rapidly on sodium dodecyl sulfate-polyacrylamide gel electrophoresis than wild-type or revertant core LPS and did not resemble Re chemotype LPS core obtained from Salmonella rfaC and rfaD mutants . These data suggest that defects in LPS core structure other than loss of heptose moieties may also be important in loss of resistance to large, hydrophilic molecules such as glycopeptides. J Trop Pediatr, 1989 Feb, 35(1), 35 - 9 Salmonella septicaemias in Kenyan children; Nesbitt A et al.; In a 5-month study of Salmonella septicaemias in Kenyan children carried out during the annual peak infection period, Salmonella typhimurium septicaemias occurred seven times more frequently than typhoid or other non-typhoid infections . Salmonella typhimurium infections were predominantly community acquired, malnourished infants from rural malaria endemic areas with poor water supply were especially vulnerable . Typical clinical features of fever, diarrhoea, and severe anaemia resembled P . falciparum malaria which often co-existed . Mortality was 18 per cent . Isolates exhibited a wide range of multidrug resistance . Typhoid affected older children, was less severe and drug sensitive. J Appl Bacteriol, 1989 Feb, 66(2), 127 - 35 An improved ELISA method for the detection of Salmonella typhimurium; Prusak-Sochaczewski E et al.; The applicability of enzyme-linked immunosorbent assay (ELISA) for the detection of salmonellas in foodstuffs was investigated . Several factors affecting the sensitivity of the ELISA, such as the type of protein used for plate post-coating, the method of antibody labelling, and accelerators for antigen-antibody and enzyme-substrate reactions, were studied . Labelling of the antibody with horseradish peroxidase and the use of o-phenylenediamine as substrate in the detection system were demonstrated to be most suitable for the enzyme assay . Based on these findings, an improved ELISA method was developed for the detection of Salmonella typhimurium . The improved technique was able to detect as few as 5 x 10(4)-10(5) cell/ml of salmonellas, and about 24 h were required to enrich the bacteria in food samples and to perform the test . With some modifications, the ELISA assay could reach a very high level of sensitivity and provide excellent reproducibility. Eur J Cancer Clin Oncol, 1989 Feb, 25(2), 255 - 61 Mutagenicity profiles of newer amsacrine analogues with activity against solid tumours: comparison of microbial and mammalian systems; Ferguson LR et al.; Amsacrine, an acridine derivative used clinically in the treatment of acute leukaemia, has formed the basis for the development of further compounds with high activity against experimental solid tumours, one of which is currently in clinical trial . We have compared the ability of these drugs to cause point mutations in bacteria, 'petite' mutations in yeast and mutations in mammalian cells . Several of the compounds are frameshift mutagens in Salmonella typhimurium TA1537 while some cause 'petite' mutagenesis in Saccharomyces cerevisiae . All are highly clastogenic and have significant mutagenic activity at the 6-thioguanine locus in cultured V79 Chinese hamster fibroblasts following 1 h drug exposures . None are mutagenic at the ouabain locus of these cells . The relationship between different indicators of mutagenicity has been studied using an additional set of amsacrine analogues, some of which are mutagenic in S . typhimurium TA98 . There is a highly significant relationship between mutation frequency (measured as resistance to 6-thioguanine) and either cytotoxicity (D37 values in a clonogenic assay) or clastogenicity (ability to induce micronuclei) . However, there is no correlation with mutagenicity in microbial systems . The results suggest that the cytotoxicity, clastogenicity and mutagenic activity of the amsacrine analogues is mediated by similar mechanisms, probably involving the enzyme DNA topoisomerase II. Cancer Lett, 1989 Feb, 44(2), 109 - 16 Characterization and mutagenicity of 1-nitrosotryptophol and 6-nitrotryptophol possible genotoxic substances associated with smoking and alcohol consumption; Tanaka K et al.; Tryptophol (Typ) is a minor product of tryptophane metabolism in humans which is increased with alcohol consumption . Typ can react rapidly with nitrite at pH 3.0 to form 1-nitrosotryptophol (NO-Typ) in high yield . This product is also formed in various organic solvents by the reaction of NO/NO2 mixtures with Typ . Under similar conditions, NO2 in the absence of NO will react with Typ to form 6-nitrotryptophol (NO2-Typ) . Both products, NO-Typ and NO2-Typ, are mutagenic when tested in the absence of rat liver microsomes with a variety of Salmonella typhimurium tester strains. Mutat Res, 1989 Feb, 216(1), 27 - 33 Azidoalanine mutagenicity in Salmonella: effect of homologation and alpha-methyl substitution; Mangold JB et al.; Azide mutagenicity in susceptible non-mammalian systems involves the requisite formation of L-azidoalanine, a novel mutagenic amino acid . The biochemical mechanism(s) of azidoalanine-induced mutagenesis, however, is not known . Previous studies of the structural requirements for azidoalanine mutagenicity suggested the importance of free L-amino acid character, and that bioactivation of azidoalanine to the ultimate mutagenic species is required . To gain more insight into possible enzymatic processing, the alpha-methyl analogue, alpha-methyl-azidoalanine, and the homologue, 2-amino-4-azidobutanoic acid, were synthesized and tested for mutagenic potency in Salmonella typhimurium strain TA1530 . In addition, azidoacetic acid, a possible azidoalanine metabolite, was prepared and tested . The results show that alpha-methyl substitution effectively blocks the mutagenic effects of azidoalanine with alpha-methyl-azidoalanine being nearly devoid of mutagenic activity . In contrast, homologation of azidoalanine to yield 2-amino-4-azidobutanoic acid produces a marked increase in molar mutagenic potency . As with azidoalanine, the mutagenic activity of this homologue is associated with the L-isomer . Azidoacetic acid, however, was only very weakly mutagenic when tested as either the free acid or ethyl ester . This low mutagenic potency may indicate that bioactivation does not involve the entry of azide-containing azidoalanine catabolite into the Kreb's cycle . The high potency of 2-amino-4-azidobutanoic acid may be indicative of more efficient bioactivation and/or greater intrinsic activity . Importantly, the latter finding clearly shows that potent azido-amino acid mutagenicity is not limited to azidoalanine alone. Epidemiol Infect, 1989 Feb, 102(1), 113 - 8 Persistent and transient clones of Salmonella typhimurium of phage type 141 recognized by biotyping; Old DC et al.; Among the 81 cultures of Salmonella typhimurium of phage type 141 examined, 72 had been isolated from Sheffield incidents in 1984-5 and 9 were Scottish isolates from 1986-7 . All of these cultures from diverse sources belonged to primary biotype 31; 79 were of full biotype 31beg and 2 anaerogenic cultures were of full biotype 31begj . This is the first known occasion on which an epidemic strain of S . typhimurium of phage type/biotype 141/31beg has been implicated in outbreaks of human or animal infection in the UK . Because previous epidemic strains of S . typhimurium of phage type 141 in the UK belonged to biotypes 1f and 9f which are phylogenetically unrelated to biotype 31beg, the likely origin of this most recent epidemic S . typhimurium strain of phage type/biotype 141/31beg is discussed. J Clin Microbiol, 1989 Feb, 27(2), 261 - 5 Detection of enterotoxigenic Escherichia coli after polymerase chain reaction amplification with a thermostable DNA polymerase; Olive DM; The direct identification of enterotoxigenic Escherichia coli from clinical specimens was examined by using the polymerase chain reaction (PCR) for amplifying the heat-labile toxin (LT) gene . Two synthetic primers, each of which was 20 bases in length, were used with the thermostable DNA polymerase from Thermus aquaticus to amplify the LT gene . The amplified PCR products were detected by either gel electrophoresis or hybridization to a 24-base synthetic oligonucleotide probe conjugated to alkaline phosphatase . The PCR method detected LT-positive bacteria but did not react with E . coli producing the heat-stable toxin, enteroinvasive E . coli, Salmonella typhi, Salmonella typhimurium, or Shigella dysenteriae . By the PCR method, a single bacterium could be detected following 30 cycles of amplification . The T . aquaticus DNA polymerase was inhibited by more than 10(3) organisms in the amplification reaction mixture . A group of 40 clinical specimens consisting of 16 LT bioassay-positive and 24 LT bioassay-negative stool specimens were tested by PCR for the presence of toxigenic E . coli . The total DNA from 100 microliters of stool specimen was extracted and partially purified with a commercially available ion-exchange column . All 16 of the bioassay-positive stool specimens were positive by PCR . In addition, one stool specimen which was bioassay negative for LT but positive for LT in a previous hybridization assay with a different LT probe was also positive by PCR . This may indicate that the LT gene is present but either is not expressed or is expressed below detectable levels . Amplification of specific DNA sequences by PCR provides a highly sensitive and specific tool for the detection of pathogenic microorganisms directly from clinical specimens without the need for prior isolation . This technique may find wide application in the detection of other organisms in addition to enterotoxigenic E.coli. J Bacteriol, 1989 Feb, 171(2), 1028 - 34 Genetic characterization of frameshift suppressors with new decoding properties; Hughes D et al.; Suppressor mutants that cause ribosomes to shift reading frame at specific and new sequences are described . Suppressors for trpE91, the only known suppressible -1 frameshift mutant, have been isolated in Escherichia coli and in Salmonella typhimurium . E . coli hopR acts on trpE91 within the 9-base-pair sequence GGA GUG UGA, is dominant, and is located at min 52 on the chromosome . Its Salmonella homolog maps at an equivalent position and arises as a rarer class in that organism as compared with E . coli . The Salmonella suppressor, hopE, believed to be in a duplicate copy of the same gene, maps at min 17 . The +1 suppressor, sufT, acts at the nonmonotonous sequence CCGU, is dominant, and maps at min 59 on the Salmonella chromosome. Carcinogenesis, 1989 Feb, 10(2), 335 - 41 Photolysis of arylazides and generation of highly electrophilic DNA-binding and mutagenic intermediates; Wild D et al.; Photolysis of arylazides with long wavelength ultraviolet (NUV) light in an aqueous medium produces short-lived reactive chemical species which bind to DNA and deoxynucleoside 3'-phosphates and induce reversion mutations in frameshift tester strains of Salmonella typhimurium . Nitrenes are known reactive products of azide photolysis, so the DNA-binding and mutagenic species is either a nitrene or a nitrene-derivative . An N-hydroxyarylamine intermediate, potentially formed from a nitrene and water, can be excluded because the mutagenic potencies of the reactive species in TA98 and in the hydroxylamine-resistant TA98/1,8-DNP6 are of the same order, and because the life-time of this species is very short . The mutagenic potency of the arylazide photolysis products decreases in the order azido-IQ greater than 1-azidopyrene greater than azido-MeIQx greater than 6-azidochrysene greater than 2-azidofluorene greater than 4-azidobiphenyl greater than 2-azido-naphthalene greater than 1-azido-naphthalene . This potency sequence correlates with that of the corresponding arylamines . Furthermore, their DNA binding products are chromatographically identical with those obtained in cellular, metabolizing systems from nitroarenes and arylamines . Therefore, the reactive, electrophilic azide photolysis product is very likely a nitrenium ion formed by protonation of a nitrene . Nitrenium ions are also the ultimate mutagens/carcinogens formed from nitroarenes and arylamines . Arylazides can therefore be considered as stabilized forms of arylnitrenium ions . The arylazide-nitrene technique reported here is new and simple and provides ready access to presumed nitrenium ions which are otherwise difficult to obtain. Mutat Res, 1989 Feb, 210(2), 263 - 9 Mutagenicity of the phenolic microsomal metabolites of 3-nitrofluoranthene and 1-nitropyrene in strains of Salmonella typhimurium; Consolo MC et al.; The environmental pollutant 3-nitrofluoranthene is metabolized in vitro and in vivo to several products including the phenolic metabolites 3-nitrofluoranthen-6-ol (3NF-6-ol), 3-nitrofluoranthen-8-ol (3NF-8-ol), and 3-nitrofluoranthen-9-ol (3NF-9-ol) . Similarly, 1-nitropyrene is metabolized to the phenolic metabolites 1-nitropyren-3-ol (1NP-3-ol), 1-nitropyren-6-ol (1NP-6-ol), and 1-nitropyren-8-ol (1NP-8-ol) . The mutagenicity of these compounds was investigated using strains of Salmonella typhimurium deficient in either certain nitroreductases or the aryl hydroxylamine O-esterificase . In TA98, 3-nitrofluoranthene and 3NF-8-ol were equally mutagenic at approximately 10(3) revertants/nmole while 3NF-6-ol and 3NF-9-ol were 10-fold less mutagenic . 1-Nitropyrene and 1NP-3-ol likewise were equally mutagenic at approximately 700 revertants/nmole and 1NP-6-ol and 1NP-8-ol were 100-fold less mutagenic . The mutagenicity of 1-nitropyrene was dependent on the 'classical nitroreductase' which is absent in TA98NR, and that of 3-nitrofluoranthene, 3NF-8-ol, and 1NP-3-ol was less dependent on this nitroreductase . Using TA98/1,8DNP6, it was determined that the mutagenicity of 3-nitrofluoranthene, 3NF-8-ol, and 1NP-3-ol but not 1-nitropyrene was dependent on the presence of the O-esterificase . 3-Nitrofluoranthene and 3NF-8-ol were mutagenic in TA100, while 3NF-6-ol and 3NF-9-ol were considerably less mutagenic . 3-Nitrofluoranthene was not mutagenic in TA100NR nor in TA100-Tn5-1,8DNP1012 . None of the phenolic metabolites of 3-nitrofluoranthene were mutagenic in TA100-TN5-1,8DNP1012 indicating a strong dependence for mutagenicity on the O-esterificase or the 1,8-dinitropyrene nitroreductase which is absent in this strain . These results are discussed in view of possible mechanisms for the differences in the mutagenicity of the phenolic metabolites of these two nitrated arenes. Mol Microbiol, 1989 Feb, 3(2), 177 - 86 Isolation, molecular characterization and expression of the ushB gene of Salmonella typhimurium which encodes a membrane-bound UDP-sugar hydrolase; Garrett AR et al.; The UDP-sugar hydrolase of Salmonella typhimurium has previously been reported to be located in both the inner and the outer membrane . We have cloned the gene, designated ushB, encoding this enzyme and determined its nucleotide sequence . No significant sequence homology with the periplasmic UDP-sugar hydrolase of Escherichia coli was found at either the DNA or protein level . However, a sequence is detectable, in the E . coli genome, which weakly hybridizes with a specific ushB probe . Polypeptide analysis has allowed the identification of the Salmonella hydrolase which has an Mr of 28,349 as compared to an Mr of 60,767 for the E . coli hydrolase . Most of the protein (approximately 90%) is located in the inner membrane . Two independent membrane fractionation procedures indicate that the remainder may be associated with the outer membrane . The deduced primary structure indicates the presence of an N-terminal signal peptide, although certain features of the region surrounding the putative processing site indicate that processing may be inefficient, or may not occur . Experiments with several inhibitors of signal peptidase function fail to demonstrate the appearance of a precursor form. Microb Pathog, 1989 Feb, 6(2), 81 - 91 Modulation of resistance to Salmonella typhimurium infection in mice by mouse hepatitis virus (MHV); Fallon MT et al.; Prior infection of mice with a field strain of mouse hepatitis virus (MHV) increased the early resistance of euthymic mice to virulent Salmonella typhimurium strain SR-11 infections (as defined by significantly fewer salmonella colony-forming units (cfu) present in spleens and livers 4 days after salmonella infection) . This increase in salmonella resistance was observed when the interval between MHV and salmonella infections was 6 days, but not at 3, 10, or 14 day intervals . The mouse Ity locus, which controls the number of intracellular salmonella, had a significant effect on the ability of MHV to induce resistance to salmonella . MHV caused an increase in resistance to salmonella in Itys (salmonella susceptible) mice at all doses of salmonella tested (100 to 10,000 cfu) . In the Ityr (salmonella resistant) mice tested the beneficial effect of MHV on salmonella resistance was small and when observed, was only present at salmonella doses of 10,000 cfu or greater . Neither the Lpsd nor Xid mutations affected the ability of MHV to increase resistance to salmonella infection . In contrast to euthymic mice, MHV infection greatly decreased the resistance of athymic (nude) mice to salmonella infection . Since the Nu locus does not affect the resistance of mice to salmonella (at 4 days post salmonella infection), these results indicate that MHV infection and the nude phenotype interact to increase susceptibility to salmonella . These findings re-emphasize the importance of keeping laboratory mice used in research free of MHV and other immunomodulatory pathogens. Microb Pathog, 1989 Feb, 6(2), 153 - 8 Localization by insertion mutagenesis of a virulence-associated region on the Salmonella typhimurium 96 kilobase pair plasmid; Rhen M et al.; The virulence-associated plasmid pEX102 of Salmonella typhimurium line TML R66 was tagged with the transposon Tn5 and the virulence of the mutants obtained was assayed in the mouse salmonellosis model . Out of 36 independent insertion mutants tested two isolates had clearly reduced virulence in (CBA x C57B1/6)F1 mice . The corresponding Tn5 elements were positioned on the restriction endonuclease map of pEX102 and found to be some 4 kilobases apart (kb) on the 96 kb virulence plasmid. Zentralbl Veterinarmed A, 1989 Feb, 36(2), 90 - 103 Clinical, endocrinological and spermatological studies after endotoxin in the ram; Wallgren M et al.; Eight rams were injected intravenously with endotoxin from Salmonella typhimurium . Blood plasma was analysed for the contents of 15-ketodihydro-PGF2 alpha, LH, testosterone, calcium and total amount of white blood cells . Semen was examined for motility, concentration, volume and morphological appearance . After castration at 4 or 16 weeks the testes were examined histologically . The total white blood cells and the calcium levels as well as LH and testosterone decreased and the levels of 15-ketodihydro-PGF2 alpha rose after the endotoxin administration . The examination of the semen showed a significant decrease in motility and a significant increase in abnormal sperm heads . The histological examination showed a slight degeneration in the seminiferous epithelium in the rams castrated at 4 weeks after the endotoxin administration; this degeneration was not seen in the rams castrated at 16 weeks . The present results indicate that endotoxin seems to exert a negative effect on the genital functions of the ram; the changes in LH and testosterone are very similar to those seen after heat induced stress . The histological changes indicate a short-lasting mild degeneration in the seminiferous epithelium. Jpn J Cancer Res, 1989 Feb, 80(2), 126 - 31 Changes in the quantity and activity of cytochrome P-450 isozymes in primary cultured rat hepatocytes; Namiki M et al.; Hepatocytes from male Sprague-Dawley rats pretreated with a cytochrome P-450 inducer, 3-methoxy-4-aminoazobenzene (3-MeO-AAB), 3-methylcholanthrene (MC) or phenobarbital (PB), were cultured in vitro, and changes in the quantity and activity of microsomal cytochrome P-450 isozymes in the cells were determined by means of immunochemical methods and a bacterial mutation test, respectively . The results of enzyme-linked immunosorbent assay using monoclonal antibodies against rat P-450 isozymes revealed that the amount of cytochrome P-450d induced by 3-MeO-AAB or MC declined rapidly during culture and fell to 10 to 15% of the initial value after 24 h . A similar tendency was observed with PB-induced cytochrome P-450b/e . By contrast, cytochrome P-450c in MC-induced hepatocytes declined more slowly than cytochrome P-450d and remained at 45 to 60% of the initial value after 24 h . Similar quantitative changes of the individual cytochrome P-450 isozymes in culture were also observed by immunoblotting using the anti-cytochrome P-450 monoclonal antibodies . Changes in the activities of individual cytochrome P-450 isozymes in hepatocytes by culture were in accordance with the quantitative changes of the cytochromes, as determined by a mutation test using Salmonella typhimurium TA 98 and carcinogenic aromatic amines . These results indicate that microsomal cytochrome P-450c in primary cultured rat hepatocytes is more stable in culture, in terms of both quantity and activity, than cytochrome P-450d and P-450b/e. Zentralbl Bakteriol Mikrobiol Hyg {B}, 1989 Feb, 187(3), 230 - 43 {The mutagenicity of organic microcontamination in the environment . II . The mutagenicity of volatile organic halogens in the Salmonella microsome test (Ames Test) with regard to the contamination of groundwater and drinking water}; Mersch-Sundermann V; To determine the sensitivity and specificity of microbial shortterm-tests for the registration of the mutagenic potency of halogenated hydrocarbons (OHV) 18 pure substances out of the groups of halomethanes, -ethanes and -ethylenes were examined with different laboratory methods (classical Ames-Test, Spot-Testing, Preincubation-Procedure) of the Salmonella-Microsome-Test (Ames-Test) . The Salmonella typhimurium- strains TA97, TA98, TA100 und TA102 were used with and without metabolic activation of Arochlor 1254 induced rat-liver microsomes . Mutagenicity with one or several procedures shows 1,1,2,2-tetrachloroethane, hexachloroethane, trichloroethylene, bromdichloromethane and bromoform without metabolic activation and dichloromethane, tetrachloromethane, 1,1,2,2-tetrachloroethane, hexachloroethane, 1,1-dichloroethylene, trans-1,2-dichloroethylene, tetrachloroethylene and bromdichloromethane with metabolic activation . The range of sensitivity amounted from microgram to nanogram values of OHV's per plate, so that the Ames-test can be a sensitive screening method sufficient for detection of mutagenic effects by several OHV's in high contaminated environmental samples even without extraction procedures. J Bacteriol, 1989 Feb, 171(2), 737 - 43 Correlation between histidine operon expression and guanosine 5'-diphosphate-3'-diphosphate levels during amino acid downshift in stringent and relaxed strains of Salmonella typhimurium; Shand RF et al.; We have analyzed the correlation of attenuator-independent expression of the Salmonella typhimurium histidine operon in vivo with levels of the "alarmone" guanosine 5'-diphosphate 3'-diphosphate . Amino acid downshift caused by serine hydroxamate addition increased his expression in a relA+ strain and decreased his expression in a relA mutant, whereas levels of guanosine 5'-diphosphate-3'-diphosphate varied in parallel with the changes in his expression in the two strains . In several experiments, overall variations in his expression ranged from 20- to 60-fold after downshift . The mild downshift allowed growth of the cultures to continue at near-preshift rates . Serine hydroxamate addition was also used to analyze the effect of amino acid downshift on induced expression of wild-type and mutant lac promoters . There was a 12-fold difference in lac expression when a relA+-relA1 pair was subjected to mild starvation but only a 3-fold difference when the strains carried the lacZpL8UV5 promoter mutation . These results suggest that guanosine 5'-diphosphate-3'-diphosphate stimulates gene expression in vivo at the level of transcription initiation. Infect Immun, 1989 Feb, 57(2), 609 - 15 Capacity of recombinant gamma interferon to activate macrophages for Salmonella-killing activity; Kagaya K et al.; The ability of recombinant gamma interferon (rIFN-gamma) to activate macrophages for Salmonella-killing activity was kinetically examined in relation to phagosome-lysosome fusion and H2O2 generation . Resident peritoneal macrophages of BALB/c mice incubated with 10(2) to 10(3) U of rIFN-gamma per ml for 12 h exhibited enhanced bactericidal activity against Salmonella typhimurium, although H2O2 generation was unaltered . In contrast, macrophages incubated with equal doses of rIFN-gamma for 48 h showed both an enhanced Salmonella-killing activity and an increased generation of H2O2 . To evaluate Salmonella-killing activities of macrophages, intracellular bacteria were assayed at 0, 2, and 8 h after infection . During the initial 2 h of infection, 12-h-activated macrophages, as well as the unstimulated control macrophages, showed a decline in bacterial population at the same rate . Over the next 6 h of infection, however, the number of viable bacteria in activated macrophages remained unchanged, whereas the number of