Publications
| Title | Abstract | Year Filter | PMID(sorted ascending) Filter |
|---|
| glutamyl-trna reductase from escherichia coli and synechocystis 6803. gene structure and expression. | in the cyanobacterium synechocystis sp. pcc 6803 and in the enterobacterium escherichia coli delta-amino-levulinic acid (ala) is formed from glutamyl-trna by the sequential action of two enzymes, glutamyl-trna reductase (glutr) and glutamate-1-semialdehyde aminotransferase. e. coli has two glutr proteins with sizes of 45 kda (glutr45) and 85 kda (glutr85) (jahn, d., michelsen, u., and söll, d. (1991) j. biol. chem. 266, 2542-2548). the hema gene, isolated from e. coli and several other eubacteri ... | 1992 | 1569081 |
| involvement of cys69 residue in the catalytic mechanism of n-hydroxyarylamine o-acetyltransferase of salmonella typhimurium. sequence similarity at the amino acid level suggests a common catalytic mechanism of acetyltransferase for s. typhimurium and higher organisms. | acetyl-coenzyme a:n-hydroxyarylamine o-acetyltransferase is ubiquitous in species ranging from bacteria to mammals and is involved in the metabolic activation of n-hydroxyarylamines derived from mutagenic and carcinogenic aromatic amines and nitroarenes. the nucleotide sequence of the gene that encodes o-acetyltransferase of salmonella typhimurium was determined, and its deduced amino acid sequence was compared with those of arylamine n-acetyltransferases (ec 2.3.1.5) of higher organisms. the ge ... | 1992 | 1569093 |
| effects of plate preparation on results in microbial mutation assays. | glucose autoclaved in an alkaline phosphate solution (heated glucose+salts, hgs) results in the production of a moiety that is nonmutagenic but can interact with a series of 4-[2-(aryl)ethenyl]-2,6-dimethylphenols to result in an increase in bacterial revertants that is dependent on the amount of hgs in the minimal agar plates. the reaction between the hgs and the chemical to form a mutagen is independent of the presence of bacteria, does not result in a nutritive analog to enhance growth of the ... | 1992 | 1572347 |
| mutagenicity of benzo(a)pyrenyl-1-sulfate in the ames test. | comparison of the mutagenicity of nine isomeric benzo(a)pyrenyl [b(a)p] phenols conjugated with either sulfate or glucuronide was carried out using strain salmonella typhimurium ta98. of the nine conjugates tested, only b(a)p-1-sulfate was mutagenic. accordingly, the mutagenicity of b(a)p-1-sulfate was compared with that of b(a)p and 1-hydroxybenzo(a)pyrene [b(a)p-1-oh] in the presence and absence of rat lung s9 and aroclor-induced liver s9 with and without an nadph-generating system. b(a)p-1-su ... | 1992 | 1572348 |
| human salmonellosis transmitted by a domestic turtle. | salmonella typhimurium was isolated in the culture test of a small child admitted to hospital suffering from febrile gastroenteritis with stools containing traces of mucus and blood. her mother also resulted positive for this microorganism. the family had recently bought a small turtle, imported from florida, at the city fair. further tests revealed salmonella typhimurium in both the turtle's feces and the water in its tank. | 1992 | 1572420 |
| prophylaxis of salmonella abortus ovis-induced abortion of sheep by a salmonella typhimurium live vaccine. | a salmonella typhimurium live vaccine with optimal level of attenuation for sheep, constructed by means of 'metabolic drift' mutations, was tested for its efficacy in preventing salmonella abortus ovis-induced abortions. in two field trials in kirgiziya, 78,000 to 100,000 first delivery sheep received a fully tolerated single dose of 10(9) c.f.u. live vaccine 2 months before to 4 months after insemination. alternatively, they were immunized twice with commercial inactivated s. abortus ovis vacci ... | 1992 | 1574918 |
| adhesion of bacteria to the cecal mucosal surface of conventional and germ-free chickens infected with eimeria tenella. | when salmonella typhimurium and clostridium perfringens were tested in conventional chickens, larger numbers of s typhimurium and c perfringens adhered to eimeria tenella-infected ceca than to uninfected ceca. in germ-free chickens, s typhimurium and c perfringens adhered to the e tenella-infected cecal mucosa more than to the uninfected cecal mucosa, but fewer bacteroides vulgatus and bifidobacterium thermophilum adhered to the e tenella-infected ceca than to the uninfected ceca. many bacteria ... | 1992 | 1575383 |
| fungal metabolism and detoxification of fluoranthene. | five metabolites produced by cunninghamella elegans from fluoranthene (fa) in biotransformation studies were investigated for mutagenic activity towards salmonella typhimurium ta100 and ta104. whereas fa displayed positive, dose-related mutagenic responses in both tester strains in the presence of a rat liver homogenate fraction, 3-fa-beta-glucopyranoside, 3-(8-hydroxy-fa)-beta-glucopyranoside, fa trans-2,3-dihydrodiol, and 8-hydroxy-fa trans-2,3-dihydrodiol were negative. 9-hydroxy-fa trans-2,3 ... | 1992 | 1575497 |
| urinary mutagenicity in vegetarians and people on a mixed-western diet. | this investigation was undertaken to determine whether the consumption of an ovolacto-vegetarian diet and a mixed-western diet by a group of 31 and 32 persons respectively resulted in the excretion of different levels of mutagens in the urine of these two dietary groups. all subjects were male participants of the "deutschlandlauf 1987" and consumed strictly controlled diets with limited energy supply and a defined protein/fat/carbohydrates relation. 24-h urines were collected before the start of ... | 1992 | 1575879 |
| genetic control of macrophage susceptibility to infection by legionella pneumophila. | legionella pneumophila readily grows in cultures of thioglycollate (tgc)-induced macrophages (mps) from a/j mice, but not in mps from balb/c mice or other mouse strains. in the present study, the growth of legionella pneumophilia in mps from a/j and balb/c mice, as well as hybrids of the two strains and back-crossed mice, was investigated to determine whether the permissiveness of growth of these bacteria was due to an inherited trait of the mps. the mps from all a/j mice supported the growth of ... | 1992 | 1575991 |
| electrophilicity as measured by ke: molecular determinants, relationship with other physical-chemical and quantum mechanical parameters, and ability to predict rodent carcinogenicity. | this paper analyzes electrophilicity data as measured by the ke system for 205 chemicals including both rodent carcinogens and non-carcinogens. multivariate statistical methods were used. the analysis identified atoms and substructures contributing to electrophilicity, and permitted to establish a theoretical method by which the ke value (electrophilicity) of chemicals can be easily estimated. in a subset of chemicals, the ke parameter was compared with other physical-chemical and quantum mechan ... | 1992 | 1576705 |
| carbamoylation reactions of n-methyl-n'-aryl-n-nitrosoureas and corresponding phenyl isocyanates to 5'-amino-5'-deoxythymidine: importance of carbamoylation in mouse skin carcinogenic processes. | carbamoylation reactions of n-methyl-n'-aryl-n-nitrosoureas (i-x: x = -och3, -ch3, -h, -cl, and -coch3) and of their corresponding phenyl isocyanates (ii-x: x = -och3, -ch3, -h, -cl and -coch3) to the amino group of 5'-amino-5'-deoxythymidine have been kinetically studied in a pbs. the pseudo-first-order rate constants (kc x 10(4) s-1, 37 degrees c) are 9.21 for i-och3, 5.11 for i-ch3, 20.1 for i-h, 3.45 for i-cl and 5.75 for i-coch3. these rate constants correlated well with the tumorigenic pot ... | 1992 | 1576720 |
| quantitative structure-activity relationships of mutagenic aromatic and heteroaromatic azides and amines. | photolysis of arylazides with long-wavelength uv light in an aqueous medium produces short-lived reactive species that bind to dna and induce mutations in salmonella typhimurium ta98. nitrenes are known reactive products of azide photolysis, so that the dna-binding and mutagenic species is either a nitrene or nitrene derivative. in the present study we presupposed that the nitrenium ion is the key intermediate. the electronic properties of 19 nitrenium ions with different chemical structures wer ... | 1992 | 1576721 |
| salmonella typhimurium enterotoxin mediated fluid secretion. | unidirectional na+ and cl- fluxes were studied in rats treated with s. typhimurium enterotoxin (s-lt). there was net absorption of na+ and cl- in the control group, while in the toxin treated animals there was net secretion of na+ and cl- (p less than 0.001). there was no change in the transport of d-glucose in the toxin treated group as compared to the control animals. the na+, k(+)-atpase pump was unaltered in the s-lt treated animals (198.67 +/- 11.23 nmoles pi/mg protein/min) as compared to ... | 1992 | 1577513 |
| genetic analysis of the genes involved in synthesis of the lipopolysaccharide core in escherichia coli k-12: three operons in the rfa locus. | the region of the escherichia coli k-12 chromosome encoding the enzymes responsible for the synthesis of responsible for the synthesis of the lipopolysaccharide (lps) core has been cloned in vivo by using a mini-mu vector. this region, formerly known as the rfa locus, comprises 18 kb of dna between the markers tdh and rpmbg. results of in vitro mutagenesis of this region with mudii1734 indicate the presence of at least 17 open reading frames or genes, a number considerably higher than expected o ... | 1992 | 1577693 |
| separation and characterization of two chemically distinct lipopolysaccharides in two pectinatus species. | lipopolysaccharides (lps) from the type strains of the anaerobic beer spoilage bacteria pectinatus cerevisiiphilus and p. frisingensis were extracted with the 5:5:8 volume ratio modification of the phenolchloroform-petroleum ether method (h. brade and c. galanos, eur. j. biochem. 122:233-237, 1982). sequential precipitations of lps with water and acetone from the phenol phase yielded lps which differed in that water-precipitable material (lps-h2o; 0.1 to 0.4% of the dry weight of the cells) was ... | 1992 | 1577699 |
| antimutagenicity of milk cultured with lactic acid bacteria against n-methyl-n'-nitro-n-nitrosoguanidine. | the antimutagenic effect of cultured milk using 71 strains of lactic acid bacteria belonging to the genus lactobacillus, streptococcus, lactococcus, and bifidobacterium on the mutagenicity of n-methyl-n'-nitro-n-nitrosoguanidine was investigated in vitro using salmonella typhimurium ta 100 as an indicator bacterium. each cultured milk sample displayed its characteristic antimutagenic effect on the mutagenicity of n-methyl-n'-nitro-n-nitrosoguanidine. the milk cultured with lactobacillus acidophi ... | 1992 | 1578035 |
| sequence of the salmonella typhimurium lt2 lexa gene and its regulatory region. | 1992 | 1579481 | |
| further observations on the serological response to experimental salmonella typhimurium in chickens measured by elisa. | an indirect elisa developed for the serological detection of salmonella typhimurium in chickens using lipopolysaccharide as detecting antigen has been evaluated further in experimental infections. following oral infection of 24-week-old laying hens with an invasive strain of s. typhimurium, high titres of specific circulating igg were induced which were maintained for 20 weeks. similar igg titres were found in egg yolk. when 4-day-old chickens were infected high antibody titres persisted for 45 ... | 1992 | 1582466 |
| apramycin resistance plasmids in escherichia coli: possible transfer to salmonella typhimurium in calves. | an outbreak of salmonellosis in calves was monitored for persistence of salmonella typhimurium excretion in faeces and the effect of treatment with apramycin. prior to treatment apramycin-resistant escherichia coli were present but all s. typhimurium isolates were sensitive. following the treatment of six calves with apramycin, apramycin-resistant s. typhimurium were isolated from two treated calves and one untreated calf. plasmid profiles of e. coli and s. typhimurium were compared and plasmids ... | 1992 | 1582469 |
| characterization of the arginine repressor from salmonella typhimurium and its interactions with the carab operator. | primer extension experiments showed that the argr gene, encoding the arginine repressor in salmonella typhimurium, is transcribed from a single promoter that is negatively regulated by arginine. a repressor overproducing strain was constructed and the repressor was purified to homogeneity. gel filtration, sedimentation and cross-linking studies established that the native repressor is a hexamer of identical 17,000 mr subunits. gel retardation experiments indicate that the apparent dissociation c ... | 1992 | 1583685 |
| evaluation of salmonella typhimurium strains harbouring defined mutations in htra and aroa in the murine salmonellosis model. | derivatives of the mouse-virulent salmonella typhimurium strain sl1344 were constructed harbouring defined mutations in htra, aroa or htra aroa combined. when administered orally or intravenously to balb/c mice, all the mutants were found to be highly attenuated. all mutants were able to confer significant protection against lethal challenge with sl1344 after a single oral dose of live organisms. sl1344 htra mutants persisted in livers and spleens at a lower level than sl1344 aroa mutants after ... | 1992 | 1584006 |
| cloning, sequencing, and overexpression of gene 16 of salmonella bacteriophage p22. | it has been suggested that gene product 16 of bacteriophage p22 forms a pore for dna transfer and/or that it functions as a pilot protein guiding the dna across the membrane. we have cloned gene 16 and determined the nucleotide sequence. within the sequenced region there is an open reading frame that could encode a protein of 609 amino acids having a molecular weight of 64,366. the hydropathic plot of this protein does not reveal putative membrane-spanning regions as expected for a protein formi ... | 1992 | 1585633 |
| tyrosine protein kinase inhibitors block invasin-promoted bacterial uptake by epithelial cells. | the ability to enter into (invade) mammalian cells is an essential virulence determinant of many pathogenic bacteria and intracellular parasites. these organisms are internalized by host cells upon attachment to their surface. however, the mechanisms used by intracellular parasites to induce internalization into host cells have not been defined. we found that the protein kinase inhibitor staurosporine blocks invasion by some pathogenic bacteria, including yersinia enterocolitica and yersinia pse ... | 1992 | 1587588 |
| invasion by salmonella typhimurium is affected by the direction of flagellar rotation. | when grown aerobically, salmonella typhimurium exhibits a low level of entry into tissue culture cells. we have isolated an s. typhimurium tn10 mutant which, when grown under aerobic conditions, efficiently invades hep-2 cells. sequencing of s. typhimurium dna adjacent to the site of the tn10 element showed that the insertion disrupted transcription of the aspartate receptor gene, tar. polar effects of the transposon on downstream genes also eliminated chemotaxis. isogenic nonchemotactic (che-), ... | 1992 | 1587617 |
| cytoskeletal composition of attaching and effacing lesions associated with enteropathogenic escherichia coli adherence to hela cells. | the cytoskeletal lesions associated with enteropathogenic escherichia coli adhering to cultured hela epithelial cells were examined by immunofluorescence microscopy. the microfilament-associated proteins actin, alpha-actinin, talin, and ezrin were localized with adherent enteropathogenic e. coli, whereas tropomyosin, keratin and vimentin (intermediate filaments), tubulin (microtubules), and vinculin were not localized. these cytoskeletal structures differed significantly from those associated wi ... | 1992 | 1587620 |
| hla-b27 expression modulates gram-negative bacterial invasion into transfected l cells. | the mechanism by which hla-b27 confers genetic susceptibility to the seronegative spondyloarthropathies ankylosing spondylitis, reiter's syndrome, and reactive arthritis, is not well understood. the current concept of an extraarticular bacterial infection functioning as the triggering event in a genetically susceptible host suggests the possibility of direct microbial-mhc interaction. we have addressed the role of hla-b27 in microbial-host cell interaction by examining invasion by putatively art ... | 1992 | 1588045 |
| production and characterisation of mouse monoclonal antibodies reactive with the lipopolysaccharide core of pseudomonas aeruginosa. | monoclonal antibodies (mabs) to the core antigen region of lipopolysaccharide (lps) of pseudomonas aeruginosa were produced from mice immunised with whole cells of heat-killed rough mutants of pseudomonas aeruginosa expressing partial or complete core lps. mabs were screened in an enzyme-linked immunosorbent assay (elisa) against three different antigen cocktails: s-form lps from three p. aeruginosa strains, r-form lps from six p. aeruginosa strains and, as a negative control, r-form lps from sa ... | 1992 | 1588587 |
| the salmonella typhimurium recj function permits growth of p22 abc phage on recbcd+ hosts. | we describe recj mutants of salmonella typhimurium. the recj gene maps between sufd and sera (min 62) and is transcribed counterclockwise. unlike recj mutants of escherichia coli, recj strains of s. typhimurium are sensitive to irradiation with uv light. this sensitivity is equivalent to or greater that that displayed by recbcd mutant strains. the residual ability of phage p22 abc (anti-recbcd) mutants to form plaques on recbcd+ strains is eliminated in recj hosts. thus host recj function appear ... | 1992 | 1588916 |
| lincomycin-induced severe colitis in ponies: association with clostridium cadaveris. | four groups of two ponies, free of fecal salmonella and clostridium cadaveris, were treated as follows: group a, control group; b, single nasogastrically administered dose of lincomycin (25 mg/kg) followed 48 h later by 3 l of c. cadaveris (10(9) organisms/ml); c, the same dose of lincomycin as group b; d, the same dose of c. cadaveris as group b on each of three occasions at 12 h intervals. groups a and d remained healthy, but groups b and c developed severe colitis 48-56 h (b) or 72 h (c) afte ... | 1992 | 1591660 |
| influence of infant diets on the ecology of the intestinal tract of human flora-associated mice. | the effect of diet on intestinal ecology was studied in germ-free mice that were inoculated orogastrically with predominant intestinal flora components isolated from the feces of breast-fed human infants. the flora components colonized the intestines of mice and persisted at fixed population levels. groups of flora- associated mice were fed either human milk, bovine milk, whey-dominant formula, or formula modifications exclusively for 2 weeks, and then examined for changes in small intestinal an ... | 1992 | 1593368 |
| nonconserved segment of the mutl protein from escherichia coli k-12 and salmonella typhimurium. | 1992 | 1594459 | |
| mass determination and estimation of subunit stoichiometry of the bacterial hook-basal body flagellar complex of salmonella typhimurium by scanning transmission electron microscopy. | the basal body, a part of the rotary motor of the bacterial flagellum, is a multiprotein assembly that consists of four rings (denoted m, s, p, and l) and an axial rod (denoted r). from analysis of scanning transmission electron microscopy images of hook-basal body preparations isolated from salmonella typhimurium, we have determined the masses of the basal body and three of its subcomplexes. the mass of the basal body (i.e., the four rings and rod) is 4400 +/- 490 kda (mean +/- sd; n = 54). the ... | 1992 | 1594581 |
| flavin-linked peroxide reductases: protein-sulfenic acids and the oxidative stress response. | sequence analyses of the streptococcus faecalis nadh peroxidase and the flavoprotein component of the salmonella typhimurium alkyl hydroperoxide reductase indicate clear evolutionary links with members of the flavoprotein disulfide reductase family. however, chemical and spectroscopic evidence demonstrate that the non-flavin redox center in nadh peroxidase is an unusual stabilized cysteine-sulfenic acid (cys-soh) derivative, and not a cystine disulfide as found in the disulfide reductases. this ... | 1992 | 1595127 |
| cross-reactive proteins of borrelia burgdorferi. | the specificity of serological tests for lyme borreliosis is impaired by cross-reacting antibodies. in order to select antigens for more specific tests, specific and cross-reactive proteins of borrelia burgdorferi must be identified. therefore, to analyze cross reactions of borrelia burgdorferi with other bacteria, rabbit immune sera against heterologous bacteria (borrelia hermsii, treponema pallidum, treponema phagedenis, leptospira interrogans (serogroup grippotyphosa), neisseria meningitidis, ... | 1992 | 1597198 |
| nucleotide sequences of bacillus subtilis flagellar biosynthetic genes flip and fliq and identification of a novel flagellar gene, fliz. | three genes from the bacillus subtilis major che-fla operon have been cloned and sequenced. two of the genes encode proteins that are homologous to the escherichia coli and salmonella typhimurium flagellar biosynthetic proteins flip and fliq. the third gene, designated fliz, encodes a 219-amino-acid protein with a predicted molecular mass of 24,872 da. fliz is not significantly homologous to any known proteins. null mutants in flip and fliz do not have flagella; however, motility can be restored ... | 1992 | 1597417 |
| molecular genetics of the flgi region and its role in flagellum biosynthesis in caulobacter crescentus. | the differentiating bacterium caulobacter crescentus has been studied extensively to understand how a relatively simple life form can govern the timing of expression of genes needed for the production of stage-specific structures. in this study, a clone containing the 5.3-kb flap region was shown to contain the flgi, chel, and flby genes arranged in an operon with transcription proceeding from flgi to flby. the predicted flgi polypeptide shows remarkable identity (44%) to the flagellar basal bod ... | 1992 | 1597425 |
| [lack of mutagenicity and teratogenicity of 16-methylene-17 alpha-acetoxy-19-norprogesterone]. | 16-methylene-17 alpha-acetoxy-19-norprogesterone (st-1435) is a new antifertility agent. st-1435 silastic capsule was implanted sc in the nuchal region of rats on d 6 of gestation at 75, 300, and 600 mg.kg-1. the rats were killed on d 20. in comparison with the control, the treated groups showed no significant differences in maternal body weights, number of corpora lutea, and the development of embryos and fetuses. the number of dead fetuses decreased and live fetuses increased slightly. st-1435 ... | 1992 | 1598838 |
| participation of rat liver cytochrome p450 2e1 in the activation of n-nitrosodimethylamine and n-nitrosodiethylamine to products genotoxic in an acetyltransferase-overexpressing salmonella typhimurium strain (nm2009). | the possible roles of cytochrome p450 (p450) enzymes in the metabolic activation of n-nitrosodimethylamine (ndma) and n-nitrosodiethylamine (ndea) by rat liver microsomes have been examined in a system containing the bacterial tester strain salmonella typhimurium nm2009, a newly developed strain showing high o-acetyltransfer activities. the dna-damaging activity could be determined by measuring expression of the umu gene in a plasmid containing the fused umuc-lacz gene construct in the bacteria. ... | 1992 | 1600620 |
| structure-activity relationship in the mutagenic effect of chiral or racemic 2-bromo-propanamides on salmonella typhimurium. | some 2-bromo-propanamides were prepared and tested for direct mutagenicity in salmonella typhimurium ta 100. results confirm the mutagenic activity of 2-bromo-n-benzyl-propanamide and indicate that it is independent of enantiomeric configuration. a variation in the chemical structure, namely, the addition of a methyl group at the benzylic carbon, causes the four resulting diastereomers to be devoid of any activity. conversely, some racemic ring-substituted methoxy and/or hydroxy derivatives of t ... | 1992 | 1600957 |
| ozone is mutagenic in salmonella. | ozone is a highly reactive gas that has been tested for genotoxicity in a number of systems. induced genetic damage resulting from ozone treatment may not be readily observed because of the high toxicity of the chemical and difficulties in generating and administering controlled concentrations. the mutagenicity of ozone was investigated in salmonella typhimurium using a plate test protocol designed for reactive vapours and gases. ozone, at two to three consecutive doses, induced weak, albeit sta ... | 1992 | 1600961 |
| mutagenicity of beta-alkyl substituted acrolein congeners in the salmonella typhimurium strain ta100 and genotoxicity testing in the sos chromotest. | the beta-alkyl substituted acrolein congeners crotonaldehyde, trans-2-pentenal, trans-2-hexenal, 2,4-hexadienal, and trans-2-heptenal were clearly mutagenic in a slightly modified preincubation ames test with salmonella typhimurium ta100 with and without s9 mix using a threefold bacterial cell density and a 90-min preincubation time, whereas trans-cis-2,6-nonadienal did not show any mutagenic activity. the greatest impediment to adequate mutagenicity testing of these compounds is their toxicity ... | 1992 | 1600962 |
| a new alpha-helical coiled coil protein encoded by the salmonella typhimurium virulence plasmid. | a new protein of salmonella typhimurium was identified and characterized. the gene (tlpa) encoding this protein (tlpa) was isolated from the large virulence-associated plasmid of s. typhimurium and sequenced in order to predict the primary structure of tlpa. tlpa encodes a 371-amino acid soluble protein with a calculated m(r) of 41600 and pi of 4.63. secondary structure predictions and sequence statistics of tlpa indicated a predominant alpha-helical configuration and presence of heptapeptide re ... | 1992 | 1601892 |
| [arterial aneurysm and myositis secondary to salmonella typhimurium bacteremia in patient with human immunodeficiency virus infection]. | 1992 | 1602861 | |
| cloning, sequencing and distribution of the salmonella typhimurium lt2 sialidase gene, nanh, provides evidence for interspecies gene transfer. | the salmonella typhimurium lt2 sialidase (neuraminidase, ec 3.2.1.18) structural gene, nanh, has been cloned and sialidase overproduced from multicopy plasmids in escherichia coli. sialidase expression was regulated positively by camp. in contrast, certain tn1000 insertions located upstream of nanh coding sequences reduced sialidase activity. a nanh chromosomal insertion mutation constructed by marker exchange demonstrated a single sialidase gene copy in s. typhimurium lt2. the complete nucleoti ... | 1992 | 1602967 |
| outbreak of food poisoning due to salmonella typhimurium dt4 in mayonnaise. | in july 1989 a large outbreak of food poisoning (68 cases) occurred at a private club in teddington (london borough of richmond-upon-thames). initial enquiries indicated that the peak of the outbreak occurred between 20th and 26th july. an epidemiological investigation (using self-completed questionnaires) was set up to determine the probable source of infection. two groups among those exposed were selected: club staff (129), and cricket teams playing in a club tournament (105). response rates w ... | 1992 | 1603924 |
| dialyzable leukocyte extract used in the prevention of salmonella infection in calves. | the protective effect of dialyzable leukocyte extract (dle) was investigated in the experimental model of salmonella infection in calves. dle was obtained from the lymphatic nodes and spleens of fattening bulls immunized with whole-cell salmonella vaccine (designated dles-im), from the same organs of calves immunized and subsequently infected with salmonella typhimurium (dles-inf), and from non-immunized fattening bulls (dlen). three doses of dles-inf and dles-im applied intravenously at 3-day i ... | 1992 | 1604794 |
| mutagenicity of airborne particulates in sagamihara city. | airborne particulates in sagamihara city were collected on quartz fibre filters using a high-volume air sampler for 14 days in each month from july 1984 to june 1985. organic components in airborne particulates were extracted by the ultrasonic extraction method using benzene-ethanol (3:1 v/v) as an extracting solvent. the mutagenecities of airborne particulates extract were measured by the pre-incubation method using salmonella typhimurium strains ta100 and ta98 with and without s-9mix. the conc ... | 1992 | 1606249 |
| susceptibility of treponema pallidum and other selected spirochaetes to zidovudine. | the antiviral nucleoside derivative zidovudine (3'-azido-3'-deoxythymidine) previously has been shown to be an effective antibacterial agent in animals infected with escherichia coli or salmonella typhimurium. since hiv infection can alter the course of human syphilis with serious consequences, it was of interest to determine if the noncultivable spirochaetal agent of syphilis, treponema pallidum, is susceptible to this compound. the progression of experimental rabbit syphilis over a three week ... | 1992 | 1607332 |
| microbic superinfection in relapse of inflammatory bowel disease. | to assess the association between symptomatic relapse of inflammatory bowel disease (ibd) and superinfection with enteropathogenic microorganisms, we determined prospectively the incidence of infections with enteropathogenic bacteria, protozoa, and helminths in patients with confirmed longstanding ibd. sixty-four patients with ibd (49 with crohn's disease [cd] and 15 with ulcerative colitis [uc]) were consecutively enrolled in the study when relapse occurred. multiple biopsies for histological a ... | 1992 | 1607606 |
| mutagenicity of organic emissions from unvented kerosene heaters in a chamber study. | a study was conducted to assess the mutagenicity of semivolatile organics and particle-bound organics emitted from unvented kerosene space heaters. the units tested included a well-tuned radiant heater and a maltuned convective heater. the tests were conducted in a 27-m3 chamber with a prescribed on/off heater usage pattern. the organic emissions were collected on teflon-coated glass filters backed by xad-2 resin. the dichloromethane-extractable organics from both the filters and the xad were an ... | 1992 | 1608068 |
| involvement of the epidermal growth factor receptor in the invasion of cultured mammalian cells by salmonella typhimurium. | salmonella infection continues to be a major world-wide health problem. one essential pathogenic feature common to all salmonella is their ability to penetrate the cells of the intestinal epithelium which are normally non-phagocytic. the internalization of salmonella into mammalian cells is thought to be a receptor-mediated phenomenon and the invasion of cultured epithelial cells depends on several salmonella genes, but nothing is known about the host determinants participating in this interacti ... | 1992 | 1608468 |
| effects of bird density on salmonella contamination of prechill carcasses. | two similar trials were conducted to evaluate the effects of bird density on salmonella contamination of processed broilers. commercial strain broiler chicks were reared in floor pens on new litter at densities of 557, 619, 697, 796, 929, and 1,115 cm2 per bird. twenty percent of the chicks in each density were gavaged directly into the crop with .5 ml of 10(8) nalidixic-acid-resistant (nar) salmonella typhimurium on day 2. twenty percent of the uninoculated birds in each density category were p ... | 1992 | 1608879 |
| occurrence of multi-resistant salmonella typhimurium infection in a pediatric hospital at calcutta. | salmonella typhimurium was isolated from 55 (15.9%) of the 347 hospitalized diarrheal children and 14 (11.1%) of the 126 non-diarrheal controls. all the 98 asymptomatic children attending hospital outpatients were negative. six (3.7%) of the 162 samples of different categories examined from the hospital were positive for s. typhimurium. finger washing of one female food handler, feces of two cats of the wards, surface of wash basin, lavatory seat and shelf yielded positive isolations. in vitro a ... | 1992 | 1612671 |
| salmonella choleraesuis and salmonella typhimurium associated with liver cells after intravenous inoculation of rats are localized mainly in kupffer cells and multiply intracellularly. | male sprague-dawley rats were inoculated intravenously with salmonella choleraesuis or salmonella typhimurium and used over 3 consecutive days to produce highly enriched (greater than 95% homogenous) preparations of kupffer and mononuclear cells (kc), liver endothelial cells (lec), and hepatocytes. the methods involved collagenase perfusion of the liver in situ, differential centrifugation of liver cells over a percoll gradient, and selective attachment of the cells to plastic or to culture dish ... | 1992 | 1612743 |
| construction of a recombinant oral vaccine against salmonella typhi and salmonella typhimurium. | the viab gene coding for the vi antigen of salmonella typhi ty2 was subcloned into expression vector pya248. the recombinant plasmid was termed smm202 and transformed into salmonella typhimurium chi 4072, an attenuated delta cya delta crp mutant. recombinant s. typimurium vi4072 had the ability to produce vi capsular polysaccharide and also to invade and colonize the small intestine, mesenteric lymph nodes, and spleen of balb/c mice. mice orally immunized with vi4072 developed serum and secretor ... | 1992 | 1612747 |
| humoral and cell-mediated immunity in mice to a 17-kilodalton lipoprotein of francisella tularensis expressed by salmonella typhimurium. | a 17-kda lipoprotein, tul4, of the facultative intracellular bacterium francisella tularensis is one of several membrane proteins that induce an in vitro response in t cells from f. tularensis-primed humans. a dna fragment of the live vaccine strain f. tularensis lvs encoding tul4 was cloned into salmonella typhimurium chi 4072, an attenuated delta cya delta crp mutant. expression of the protein by the recombinant s. typhimurium chi 4072 (ptul4-15) was maintained after passage in balb/cj mice. w ... | 1992 | 1612751 |
| dissemination and proliferation of salmonella typhimurium in genetically resistant and susceptible mice. | genetically resistant a/j and cba mice were inoculated intraperitoneally with either 10(3) or 10(4) organisms of a virulent strain of salmonella typhimurium; susceptible c57bl/6j and balb/c mice were inoculated with either 10(2) or 10(3) organisms. except with the smaller dose in resistant mice, fatal infection ensued. bacteraemia occurred within 1 h after inoculation, except that it was not detectable during the first 6 h in the susceptible mice inoculated with 10(2) organisms. from day 2, the ... | 1992 | 1613775 |
| crystallization and preliminary x-ray studies of the liganded lysine, arginine, ornithine-binding protein from salmonella typhimurium. | the periplasmic binding protein lao from salmonella typhimurium, which is involved in lysine, arginine and ornithine transport, has been crystallized together with one of its ligands, arginine (lao-arg). preliminary x-ray diffraction studies of lao-arg crystal show that it belongs to the orthorhombic space group p2(1)2(1)2(1) and has the unit cell dimensions of a = 37.65 a, b = 59.45 a, c = 115.91 a. crystals of the lao-arg complex diffract beyond 2.0 a resolution. | 1992 | 1613794 |
| teas and tea components as inhibitors of carcinogen formation in model systems and man. | epidemiological evidence points to a cancer protective role of green-yellow-orange vegetables and fruits. the involvement of teas as a protective factor in carcinogenesis has not received the attention it seems to merit. to gain relevant information, attempts were made to stimulate in vitro those conditions to which human groups are actually exposed. | 1992 | 1614999 |
| serological response of chickens naturally infected with salmonella typhimurium detected by elisa. | four laying flocks of chickens in britain, each with a history of salmonella typhimurium infection, were investigated serologically and bacteriologically. blood samples were taken from identified birds from a single house on each site and sent to the central veterinary laboratory, weybridge for serological examination using enzyme-linked immunosorbent assays (elisa) and rapid slide agglutination test (rst) using stained s. pullorum. the identified birds were taken to the local veterinary investi ... | 1992 | 1617398 |
| salmonella typhimurium strains expressing human arylamine n-acetyltransferases: metabolism and mutagenic activation of aromatic amines. | epidemiological studies have established the carcinogenic risk of occupational exposure to aromatic amines such as benzidine, beta-naphthylamine, and 4-aminobiphenyl. metabolic activation of these chemicals to reactive, genotoxic electrophiles, via enzymatic n-oxidation and subsequent conjugation reactions, is necessary for their carcinogenic potential to be realized. many aromatic amines are mutagenic in prokaryotic test systems, in the presence of exogenous mammalian activating enzymes such as ... | 1992 | 1617672 |
| purification of the mglc/e membrane proteins of the binding protein-dependent galactose transport system of salmonella typhimurium. | the high affinity galactose transport system of salmonella typhimurium consists of four proteins, a periplasmic galactose binding protein (the mglb protein), and three inner membrane-associated proteins, the mgla, mglc and mgle proteins. we purified the mglc/e proteins from an mglc/e hyperproducing strain after solubilisation of inclusion bodies in guanidine hydrochloride followed by renaturation in a detergent-containing buffer and affinity chromatography on a mglb-sepharose column. the mglc/e ... | 1992 | 1618318 |
| evidence that mutations in a loop region of the alpha-subunit inhibit the transition from an open to a closed conformation in the tryptophan synthase bienzyme complex. | rapid-scanning stopped-flow (rssf) uv-visible spectroscopy has been used to investigate the effects of single amino acid mutations in the alpha-subunit of the salmonella typhimurium tryptophan synthase bienzyme complex on the reactivity at the beta-subunit active site located 25 to 30 a distant. the pyridoxal 5'-phosphate (plp) cofactor provides a convenient spectroscopic probe to directly monitor catalytic events at the beta-active site. single substitutions of phe for glu at position 49, leu f ... | 1992 | 1618800 |
| redesigned purification yields a fully functional puta protein dimer from escherichia coli. | proline utilization by escherichia coli and salmonella typhimurium requires expression of genes putp (encoding a proline transporter) and puta. genetic data indicate that the puta protein is both put repressor and a respiratory chain-linked dehydrogenase. we report a redesigned purification procedure as well as the physical characteristics and biological activities of the puta protein purified from e. coli. the purified protein was homogeneous as determined by electrophoresis performed under den ... | 1992 | 1618807 |
| identification of 5,6-dimethylbenzimidazole as the co alpha ligand of the cobamide synthesized by salmonella typhimurium. nutritional characterization of mutants defective in biosynthesis of the imidazole ring. | the co beta-cyano derivative of the cobamide isolated from salmonella typhimurium was identified as co alpha-(alpha-5,6-dimethylbenzimidazolyl)-co beta-cyanocobamide, indicating that this bacterium synthesizes 5,6-dimethylbenzimidazole (dmb) de novo. we found that mutants deficient in the synthesis of dmb can incorporate benzimidazole without modification to form co alpha-(alpha-benzimidazolyl)cobamide, a cobamide that is physiologically active. the analysis of the nutritional requirements of mu ... | 1992 | 1618831 |
| protective role of aqueous turmeric extract against mutagenicity of direct-acting carcinogens as well as benzo [alpha] pyrene-induced genotoxicity and carcinogenicity. | turmeric (curcuma longa linn.) has been shown to inhibit chemical carcinogenesis. in this study, we compared the chemopreventive efficacy of an aqueous turmeric extract (aqte) and its constituents, curcumin-free aqueous turmeric extract (cfaqte) and curcumin, using the salmonella typhimurium mutagenicity assay and the bone marrow micronucleus test in female swiss mice. aqte exhibited antimutagenic activity against direct-acting mutagens, 4-nitro-o-phenylenediamine and 1-methyl-3-nitro-1-nitrosog ... | 1992 | 1618892 |
| demonstration of cel operon expression of escherichia coli, salmonella typhimurium, and pseudomonas aeruginosa at elevated temperatures refractory to their growth. | when escherichia coli was incubated at the growth-refractory temperatures of 48 and 54 degrees c, expression of the cel operon was demonstrated by phospho-beta-glucosidase activity. this enzyme activity was also detected at the growth-refractory temperatures in salmonella typhimurium and pseudomonas aeruginosa. thermotolerant and mesothermophilic mutants of e. coli, s. typhimurium, and p. aeruginosa, able to grow with generation times of 30 to 40 min at 48 and 54 degrees c, exhibited phospho-bet ... | 1992 | 1622253 |
| antimicrobial action of nisin against salmonella typhimurium lipopolysaccharide mutants. | the antimicrobial activity of nisin against outer membrane lipopolysaccharide mutants of salmonella typhimurium lt2 was investigated. nisin sensitivity was associated with the extent of saccharide deletions from the outer membrane core oligosaccharide. the results indicated that the core oligosaccharide in lipopolysaccharide plays a role in nisin sensitivity. | 1992 | 1622254 |
| acid adaptation promotes survival of salmonella spp. in cheese. | salmonella typhimurium was adapted to acid by exposure to hydrochloric acid at ph 5.8 for one to two doublings. acid-adapted cells had increased resistance to inactivation by organic acids commonly present in cheese, including lactic, propionic, and acetic acids. recovery of cells during the treatment with organic acids was increased 1,000-fold by inclusion of 0.1% sodium pyruvate in the recovery medium. acid-adapted s. typhimurium cells survived better than nonadapted cells during a milk fermen ... | 1992 | 1622286 |
| polymyxin b octapeptide and polymyxin b heptapeptide are potent outer membrane permeability-increasing agents. | polymyxin b octapeptide (pbop) and polymyxin b heptapeptide (pbhp) were found to be effective permeabilizers of the outer membrane of escherichia coli and salmonella typhimurium. pbop was as effective as polymyxin b nonapeptide (pmbn), the known very potent permeabilizer. as low a pbop concentration as 1 microgram/ml sensitized e. coli to rifampicin by a factor of 100. three micrograms of pbop per ml was sufficient to sensitize this target to all the other tested hydrophobic antibiotics (erythro ... | 1992 | 1624376 |
| an operon of bacillus subtilis motility genes transcribed by the sigma d form of rna polymerase. | two genes controlling motility functions in bacillus subtilis were identified by dna sequence analysis of a chromosomal fragment containing a strong promoter for sigma d rna polymerase. previous studies had shown that this sigma d-dependent promoter controls synthesis of a 1.6-kb transcript in vivo and in vitro. sequence analysis revealed that the 1.6-kb transcript contains two open reading frames coding for protein sequences homologous to the escherichia coli mota and motb gene products, respec ... | 1992 | 1624413 |
| effect of salmonella typhimurium ferric uptake regulator (fur) mutations on iron- and ph-regulated protein synthesis. | fur is an important regulatory protein known to function in the presence of iron as a repressor of iron-controlled genes. it was recently discovered that fur is also essential to salmonella typhimurium for mounting an adaptive acid tolerance response (j. w. foster, j. bacteriol 173:6896-6902, 1991). because little is known about the effect of fur on the physiology of this enteric pathogen, a systematic two-dimensional polyacrylamide gel electrophoresis (page) analysis was conducted to identify p ... | 1992 | 1624426 |
| molecular and functional characterization of the salmonella invasion gene inva: homology of inva to members of a new protein family. | one of the earliest steps in the pathogenic cycle of the facultative intracellular pathogen salmonella spp. is the invasion of the cells of the intestinal epithelium. we have previously identified a genetic locus, inv, that allows salmonella spp. to enter cultured epithelial cells. inva is a member of this locus, and it is the first gene of an operon consisting of at least two additional invasion genes. we have constructed strains carrying nonpolar mutations in inva and examined the individual c ... | 1992 | 1624429 |
| physical mapping of repetitive extragenic palindromic sequences in escherichia coli and phylogenetic distribution among escherichia coli strains and other enteric bacteria. | repetitive extragenic palindromic (rep) sequences are highly conserved inverted repeat sequences originally discovered in escherichia coli and salmonella typhimurium. we have physically mapped these sequences in the e. coli genome by using southern hybridization of an ordered phage bank of e. coli (y. kohara, k. akiyama, and k. isono, cell 50:495-508, 1987) with generic rep probes derived from the rep consensus sequence. the set of rep probe-hybridizing clones was correlated with a set of clones ... | 1992 | 1624447 |
| structures of the rfab, rfai, rfaj, and rfas genes of escherichia coli k-12 and their roles in assembly of the lipopolysaccharide core. | analysis of the sequence of a 4.1-kb rfa region downstream from rfap revealed four genes. the first of these encodes a basic protein of 36,730 da and does not correspond to any known rfa gene. it has been designated rfas. the second gene was identified as rfab on the basis of its ability to complement a salmonella typhimurium rfab mutant and encodes a 42,060-da protein. the third and fourth genes encode proteins of 39,423 and 36,046 da which are strongly homologous to the rfai and rfaj proteins ... | 1992 | 1624461 |
| comparison of lipopolysaccharide biosynthesis genes rfak, rfal, rfay, and rfaz of escherichia coli k-12 and salmonella typhimurium. | analysis of the sequence of a 4.3-kb region downstream of rfaj revealed four genes. the first two of these, which encode proteins of 27,441 and 32,890 da, were identified as rfay and rfaz by homology of the derived protein sequences of their products to the products of similar genes of salmonella typhimurium. the amino acid sequences of proteins rfay and rfaz showed, respectively, 70 and 72% identity. genes 3 and 4 were identified as rfak and rfal on the basis of size and position, but the deriv ... | 1992 | 1624462 |
| molecular modelling of the three-dimensional structure and conformational flexibility of bacterial lipopolysaccharide. | molecular modelling techniques have been applied to calculate the three-dimensional architecture and the conformational flexibility of a complete bacterial s-form lipopolysaccharide (lps) consisting of a hexaacyl lipid a identical to escherichia coli lipid a, a complete salmonella typhimurium core oligosaccharide portion, and four repeating units of the salmonella serogroup b o-specific chain. x-ray powder diffraction experiments on dried samples of lps were carried out to obtain information on ... | 1992 | 1624466 |
| involvement of the arc system in redox regulation of the cob operon in salmonella typhimurium. | transcription of the cobalamin biosynthetic (cob) genes in salmonella typhimurium is induced during anaerobic growth. two mutants defective in induction of the cob operon were isolated. the mutants showed decreased anaerobic induction, both during conditions of fermentation and anaerobic respiration, relative to the wild type. the mutant genes were localized by hfr and transduction mapping to 100 minutes and 69 minutes on the chromosome. the mutants were sensitive to the dye toluidine blue. the ... | 1992 | 1625578 |
| the effect of exposure to a delta cya/delta crp mutant of salmonella typhimurium on the subsequent colonization of swine by the wild-type parent strain. | this study characterizes the clinical response and colonization pattern of caesarean-derived, colostrum-deprived swine exposed to a delta cya/delta crp mutant (chi 4233) of s. typhimurium and challenged with the wild-type parent strain. chi 4233 was mildly virulent in swine and induced transient fever and soft stools. chi 4233 colonized the ileum, cecum, liver, spleen, tonsils, and mandibular and ileocolic lymph nodes of swine in a manner similar to the parental wild-type, but the numbers of s. ... | 1992 | 1626370 |
| genotoxicity studies on sertaconazole. | a series of 6 studies has been performed to evaluate the potential genotoxic effect of 7-chloro-3-[1-(2,4-dichlorophenyl)-2-(1h- imidazol-1-yl)ethoxy-methyl]benzo[b]thiophene (sertaconazole, fi 7045, cas 99592-32-2). from these studies, the reverse mutation assay on salmonella typhimurium, sex-linked recessive lethal mutations on drosophila and genetic mutations in cultured mammal cells allowed to study the genetic mutations in prokaryotes and eukaryotes. in vitro and in vivo chromosomal aberrat ... | 1992 | 1627196 |
| cytokine-induced resistance to microbial infections in normal, immunosuppressed and bone marrow transplanted mice. | we studied the efficacy of in vivo and in vitro treatments with il-1, il-2, il-3, and gm-csf in the protection against bacterial (salmonella typhimurium), fungal (candida albicans) and viral (influenza virus a/pr8) infections, of normal, sublethally irradiated and lethally irradiated, bone marrow (bm) reconstituted mice. in parallel, the cytokines were tested for their ability to potentiate hematopoietic activity in vitro and in vivo. we demonstrate that, under the experimental conditions employ ... | 1992 | 1628132 |
| antimutagenicity of ellagic acid towards the food mutagen iq: investigation into possible mechanisms of action. | the ability of the plant phenol ellagic acid to inhibit the mutagenicity of the food mutagen iq was evaluated using salmonella typhimurium strain ta98 in the ames mutagenicity test. ellagic acid caused a concentration-dependent decrease in the s-9- and microsome-mediated mutagenicity of iq. the plant phenol did not interact directly with the iq-derived mutagenic species and did not modify the cytosol-mediated activation of the promutagen. at the concentrations used in the mutagenicity studies, e ... | 1992 | 1628864 |
| epidemiological markers of salmonella typhimurium isolates in rome. | the phage type, antimicrobial resistance pattern, colicinogenic activity and dna plasmid content of 172 strains of salmonella typhimurium isolated in rome from 1984 to 1986 were determined; 142 isolates were from patients with enteritis, 30 were from asymptomatic subjects. most of the phage types identified were isolated during 2 or 3 of the study years; others, e.g., pt141, pt 204c and pt 194 were isolated during 1 year only, and only the last of these was isolated in large numbers. phage typin ... | 1992 | 1629894 |
| mutagenicity of trinitrotoluene and its metabolites formed during composting. | tnt was mutagenic for salmonella typhimurium without the need of a rat liver metabolic activation system (s9). the mutagenic potency of tnt decreased in proportion to the number of nitro groups that were reduced to the amino form. the presence of a nitro group on the 4 position of the diamino congener is necessary for mutagenicity. among the active congeners, mutagenicity was generally greater for ta100 than ta98, except that for the 4-amino congener the reverse was true. in cases when s9 was in ... | 1992 | 1629932 |
| purification and characterization of a salmonella typhimurium agglutinin from gut mucus secretions. | one of the earliest events in salmonella typhimurium pathogenesis seems to be the interaction of the bacterium with the mucus of the gut. after exposing s. typhimurium to guinea-pig colon, we were able to demonstrate by electron microscopy that s. typhimurium bacteria were trapped on, or in, the mucus layer. specific components isolated from crude mucus secretions were found to aggregate the bacteria. the degree of bacterial aggregation was dependent on the protein concentration of the crude muc ... | 1992 | 1630296 |
| immunosuppression induced by attenuated salmonella: effect of lps responsiveness on development of suppression. | a live, avirulent strain of salmonella typhimurium, sl3235, was previously shown to afford protection against virulent salmonella challenge in three mouse strains of the c3h lineage, c3h/hej, c3heb/fej, and c3h/hencrlbr, which differ in their innate susceptibility to salmonella infection, as well as in their responsiveness to lipopolysaccharide (lps). concurrent with protection, however, sl3235 was found to induce greater than 90% reduction in proliferative responses of splenocytes from immunize ... | 1992 | 1630297 |
| impaired resistance to infection does not increase the virulence of salmonella htra live vaccines for mice. | we have described a new class of live attenuated salmonella vaccines harbouring lesions in htra, a stress protein gene previously. the virulence and invasiveness of salmonella htra mutants was investigated in three models of increased susceptibility to salmonella infection. these included balb/c mice, either given sublethal whole body irradiation (350 r) or administered rabbit anti-tnf alpha antiserum, and (cba/nfemalexbalb/cmale)f1 male mice which express the xid sex-linked b cell defect of cba ... | 1992 | 1630300 |
| nucleotide sequence, function, activation, and evolution of the cryptic asc operon of escherichia coli k12. | the cryptic asc (previous called "sac") operon of escherichia coli k12 has been completely sequenced. it encodes a repressor (ascg); a pts enzyme iiasc for the transport of arbutin, salicin, and cellobiose (ascf); and a phospho-beta-glucosidase that hydrolyzes the sugars which are phosphorylated during transport (ascb). ascg and ascfb are transcribed from divergent promoters. the cryptic operon is activated by the insertion of is186 into the ascg (repressor) gene. the ascfb genes are paralogous ... | 1992 | 1630307 |
| insertion (sufb) in the anticodon loop or base substitution (sufc) in the anticodon stem of trna(pro)2 from salmonella typhimurium induces suppression of frameshift mutations. | the dominant +1 frameshift suppressors sufa6, sufb1 and sufb2, in salmonella typhimurium act at runs of c and affect trna(pro)1, trna(pro)2 and trna(pro)2, respectively. a recessive +1 frameshift suppressor, sufc, has a similar suppressor specificity (riddle, d.l., and roth, j.r., mol. biol. 66, 483 and 495, 1972). we show that sufc strains harbour two frameshift suppressors of which one, sufx201, is allelic to sufb. we cloned the sufb+ wild type allele and by recombination in vivo the mutations ... | 1992 | 1630916 |
| the cytoplasmic component of the bacterial flagellar motor. | we have used electron microscopy to examine freshly isolated salmonella typhimurium and escherichia coli basal flagellar fragments, purified without resort to extremes of ph or ionic strength. such fragments contain the large bell-like basal structures visualized recently in freeze-substituted or fixed preparations. we have found mot (non-motile) mutants produced by lesions in fli genes (g, m, n) in which the bell structures do not coisolate with the flagellar basal body. the coisolation of the ... | 1992 | 1631080 |
| identification and molecular characterization of a salmonella typhimurium gene involved in triggering the internalization of salmonellae into cultured epithelial cells. | penetration of intestinal epithelial cells is an important step in the pathogenesis of salmonella infections. we have characterized a gene, inve, that is necessary for salmonella invasion of cultured epithelial cells. the predicted amino acid sequence of inve showed significant homology to the yersinia outer membrane protein yopn (lcre). strains of salmonella carrying mutations in inve were unable to penetrate henle-407 human intestinal cells and madin-darby canine kidney cells, although they we ... | 1992 | 1631083 |
| localization of the salmonella typhimurium flagellar switch protein flig to the cytoplasmic m-ring face of the basal body. | the direction of rotation of the bacterial flagellum is determined by the flagellar switch. we have localized flig, one of the switch proteins of salmonella typhimurium, to the cytoplasmic face of the m ring of the flagellar basal body. this localization was made possible by the discovery of two spontaneous mutants in which the flif (m ring) and flig (switch) genes were fused in-frame. in the first mutant, a deletion of 7 base pairs at the 3' end of flif resulted in an essentially full-length fu ... | 1992 | 1631122 |
| sensitivity of salmonella typhimurium ta97a to the type of agar used for preparation of vogel-bonner plates. | recent problems with the supply of difco bacto agar have forced some laboratories to evaluate alternative agars for use in the salmonella/microsome assay. this led to the independent observation in two laboratories (boots and glaxo) that salmonella typhimurium ta97a is sensitive to certain types of agar that may be used to prepare vogel-bonner minimal medium plates. a programme of work was, therefore, undertaken to investigate this phenomenon; 9-aminoacridine hydrochloride (at boots) and 4-nitro ... | 1992 | 1635450 |
| bacterial mutagenic evaluation of a series of 4' substituted derivatives of 3-benzylidenamino-5h-1,2,3-triazin[5,4b]indol-4-one. | the mutagenicity of ten triazinoindole derivatives was studied in bacteria. the compounds form part of a 3-(4'-substituted-benzylidenamino)-5h-1,2,3-triazin[5,4-b]in dol-4-one series and differ in the physicochemical properties of the substituent at the 4' position of the benzylidenamino group: -h, -oh, -cooh, -och3, -cooch3, -nhcoch3, -c1, -no2, -c6h5, and -oc6h5. they were tested in the ta97, ta98, ta100, and ta102 strains of salmonella typhimurium, both with and without metabolic activation, ... | 1992 | 1635453 |
| influence of the triazine ring on the mutagenicity of triazinoindoles and some congeners. | three compounds, which could be considered as precursors or derivatives of the 3-(4'-substituted-benzylidenamino)5h- 1,2,3-triazin[5,4b]indol-4-one series, were selected from the study of their mutagenic activity. ames tests were performed study of their mutagenic activity. ames tests were performed using the salmonella typhimurium strains ta97, ta98, ta100, and ta102, according to the preincubation procedure, both with and without metabolic activation. the 3-amino-5h-1,2,3-triazin[5,4b]indol-4- ... | 1992 | 1635454 |
| study on the mutagenicity of brandy with the ara test. | the forward mutation assay to l-arabinose resistance (ara test) in salmonella typhimurium was used to demonstrate that evaporated residues of brandy had direct-acting mutagenic activity. the mutagenicity covered a 100-fold range, from 13482 to 127 arar induced mutants/ml brandy equivalent. rat liver s9 mix suppressed the mutagenic activity of brandy in the ara test. the inactivating capacity was independent of microsomal monoxygenase enzymes and appeared to be mediated through a heat stable comp ... | 1992 | 1635459 |
| signal peptidase i of bacillus subtilis: patterns of conserved amino acids in prokaryotic and eukaryotic type i signal peptidases. | signal peptidases (spases) remove signal peptides from secretory proteins. the sips (signal peptidase of subtilis) gene, which encodes an spase of bacillus subtilis, was cloned in escherichia coli and was also found to be active in e.coli. its overproduction in b.subtilis resulted in increased rates of processing of a hybrid beta-lactamase precursor. the sips protein consisted of 184 amino acids (mol. wt 21 kda). the protein showed sequence similarity with the leader peptidases of e.coli and sal ... | 1992 | 1639057 |
| molecular analysis of mutations induced by the intercalating agent ellipticine at the hisd3052 allele of salmonella typhimurium ta98. | we have used dna colony hybridization, the polymerase chain reaction (pcr), and direct dna sequencing to determine the mutations induced by the intercalating agent ellipticine in salmonella typhimurium ta98 in the presence of s9. of 400 ellipticine-induced revertants that were selected at a mutant yield that was ninefold over the background, 85.5% contained a gc or cg deletion within a common cgcgcgcg hotspot; this deletion occurred among 47% of the spontaneous revertants. in addition to this ho ... | 1992 | 1639078 |
| a 66-kilodalton heat shock protein of salmonella typhimurium is responsible for binding of the bacterium to intestinal mucus. | salmonella typhimurium infections have increased during the last few years. however, the interplay of virulence factors in s. typhimurium pathogenesis is still poorly understood, particularly with regard to the mechanisms and components of the bacterium which are involved in its interaction with the intestinal mucus. we have observed that s. typhimurium is aggregated by incubation with colonic mucus (guinea pig model). to quantify this phenomenon, an aggregation assay was established. by using t ... | 1992 | 1639475 |