| reactivity of lipopolysaccharides from various salmonella sr and r chemotypes ra-re mutants with concanavalin a. | lipopolysaccharides from different r mutants of salmonella minnesota and salmonella typhimurium belonging to chemotypes ra to re, as well as from three sr mutants of salmonella typhimurium were selected for a study of their precipitability with concanavalin a. predictions as to the outcome of the reaction could be made since both the chemical structure of the salmonella r lipopolysaccharides and structural requirements for a positive reaction with concanavalin a are well established. precipitati ... | 1975 | 766503 |
| [multiplication and virulentization of salmonella typhimurium in mayonnaise]. | | 1975 | 766577 |
| [multiplication and virulentization of salmonella typhimurium in moist forage mixture for broilers]. | | 1975 | 766578 |
| [lysogeny and virulence of salmonella typhimurium]. | | 1975 | 766579 |
| the mutagenicity of chloroethylene oxide, chloroacetaldehyde, 2-chloroethanol and chloroacetic acid, conceivable metabolites of vinyl chloride. | previous investigations have shown that the carcinogen vinyl chloride causes base-pair substitution in the bacterium salmonella typhimurium. the ability of four conceivable metabolites-chloroethylene oxide, chloroacetaldehyde, 2-chloroethanol and chloroacetic acid-to cause base-pair substitution directly in salmonella typhimurium ta1535 has been compared. the main comparison was performed at initial concentrations from 0.1 to 1.5 mm. in this region, however, a mutagenic effect was observed only ... | 1976 | 767010 |
| mutagenicity of 5-nitroacenaphthene in salmonella. | 5-nitroacenaphthene was proved to be mutagenic on ta100 and ta98 of salmonella typhimurium with or without metabolic activation by s-9 mix. a possible metabolite, 5-hydroxyacenaphthene, carcinogenicity of which had not been observed, was non-mutagenic on ta100 and ta98, with or without metabolic activation. | 1975 | 767193 |
| a ribonuclease i deficient mutant (mb24) of salmonella typhimurium. | | 1975 | 767251 |
| biosynthesis and assembly of envelope lipoprotein in a glycerol-requiring mutant of salmonella typhimurium. | a glycerol-requiring mutant of salmonella typhimurium was used in a study of the biosynthesis and assembly of a structural lipoprotein in the cell envelope of gram-negative bacteria. upon removal of glycerol from the growth medium, the biosynthesis of lipoprotein, as measured by radioactive arginine incorporation, was reduced by the same extent as that of other envelope proteins, the cumulative incorporation of arginine being 20% of that of the unstarved control cells. however, the incorporation ... | 1976 | 767331 |
| genetic transfer of salmonella o antigens to escherichia coli o8. | his+ hybrids from a cross between a salmonella typhimurium donor and an escherichia coli o8 recipient expressed e. coli o8 specificity and in addition salmonella o4,12-specificity. this indicated that the recipients had received the his-linked donor rfb cluster determining the synthesis of s. typhimurium o-specific repeat units and that the rfb genes of both mating partners are functional in these hybrids. chemical analyses showed that the hybrids contained an e. coli o8 lipopolysaccharide (o an ... | 1976 | 768409 |
| role of the bacteriophage p22 tail in the early stages of infection. | the initial binding of phage p22 to its host, salmonella typhimurium, is dependent in a linear fashion on the number of tail parts per phage head. (the normal head has six.) there is also a later step which depends on tail parts. this step must occur some time after hydrolysis of the o antigen has been initiated and before ejection of phage dna from the head is complete. this step causes pfu to depend on approximately the third power of the number of tail parts per head. | 1976 | 768524 |
| an outbreak of s typhimurium in sheep and its consequences. | an outbreak of salmonella typhimurium in an upland sheep flock was characterised by rapid spread and heavy mortalities in ewes and young lambs. clinical signs included diarrhoea and abortion. abomasitis was the most striking and consistent post mortem lesion. vaccination was the only control method that was apparently successful. infection also occurred in the cattle, farm personnel, and a dog. following the outbreak, pasture contamination and excreting cattle provided a reservoir of infection s ... | 1976 | 769302 |
| effect of resistance possessed by certain enteric microorganisms upon orally inoculated salmonella. | mice shedding aerobic gram-negative microorganisms with high levels of resistance to tetracycline were orally inoculated with salmonella typhimurium. levels of resistance of salmonella isolated from tissue were shown not to be increased and, in most instances, were lower than preinoculation levels. | 1976 | 769613 |
| elimination of resistance determinants from r-factor r1 by intercalative compounds. | eighteen deoxyribonucleic acid (dna)-complexing compounds, among them 15 intercalative substances, and, additionally, nalidixic acid eliminated with different frequencies four antibiotic resistance determinants from the r-factor r1, carried by salmonella typhimurium. eliminating concentrations did not inhibit growth of the bacteria. the most active compound was "nitroacridine ii" {1-diethylamino-3-[(6-nitro-9-acridinyl)amino]propanol}. when 14 compounds which had been tested at a standard concen ... | 1976 | 769675 |
| outer membrane of salmonella typhimurium. transmembrane diffusion of some hydrophobic substances. | the outer membrane, which is composed of lipopolysaccharide, phospholipids, and proteins, is a layer of the cell wall of gram-negative bacteria, and apparently acts as a penetration barrier for various substances. it had been shown by other workers that "deep rough" mutants of salmonella typhimurium, whose lipopolysaccharides lack most of the saccharide chains, were much more sensitive than the wild type strain to certain antibiotics and dyes, but not to others. we found that the former group of ... | 1976 | 769835 |
| regulation of purine utilization in bacteria. vi. characterization of hypoxanthine and guanine uptake into isolated membrane vesicles from salmonella typhimurium. | uptake of hypoxanthine and guanine into isolated membrane vesicles of salmonella typhimurium tr119 was stimulated by 5'-phosphoribosyl-1'-pyrophosphate (prpp). for strain proab47, a mutant that lacks guanine phosphoribosyltransferase, prpp stimulated uptake of hypoxanthine into membrane vesicles. no prpp-stimulated uptake of guanine was observed. for strain tr119, guanosine 5'-monophosphate and inosine 5'-monophosphate accumulated intravesicularly when guanine and hypoxanthine, respectively, wer ... | 1976 | 770425 |
| tryptophan operon regulation in interspecific hybrids of enteric bacteria. | we examined tryptophan regulation in merodiploid hybrids in which a plasmid carrying the trp operon of escherichia was introduced into trp mutants of other enteric genera, or in which a plasmid carrying the trpr+ (repressor) gene of e. coli was transfered into fully constitutive trpr mutants of other genera. in these hybrids the trp operon of one species is controlled by the repressor of a different species. similar investigations were possible in transduction hybrids in which either the trp ope ... | 1976 | 770450 |
| derivation and properties of f-prime factors in escherichia coli carrying nitrogen fixation genes from klebsiella pneumoniae. | a his+ nif+ escherichia coli k12, hfr strain (unf43) was constructed by an intergeneric mating between a klebsiella pneumoniae donor strain (hf3) and a his-hfr e. coli strain (sbi824) which transfers his as an early marker. an f-prime nif plasmid, fn39, carrying genes which correspond to the e. coli chromosomal region, metg gnd his shia, but excluding purf and arod, was isolated from unf43. translocation of carbenicillin resistance genes from a p-type r-factor, r68, to fn39 increased the stabili ... | 1976 | 772161 |
| adjuvant effect of lipid a obtained from salmonella typhimurium on antibody response in mouse spleen. the role of carriers conjugated to lipid a. | | 1975 | 772258 |
| salmonella typhimurium infection in guinea pigs: observations on monitoring and control. | a spontaneous outbreak of salmonellosis in a guinea pig colony was caused by salmonella typhimurium. a simple, comprehensive monitoring procedure, consisting of mass fecal sampling, was developed. using the monitoring system described, the disease was eliminated by: 1) removal of animals in pens in contact with salmonella, and 2) strict hygienic procedures. it was not necessary to depopulate the colony in order to control the disease. | 1976 | 772307 |
| chemotaxis in bacteria. | bacterial chemotaxis, the movement of motile bacteria toward or away from chemicals, was discovered nearly a century ago by engelmann (1) and pfeffer (2,3). the subject was actively studied for about 50 years, but then there were very few reports until quite recently. for reviews of the literature up to about 1960, see berg (4), weibull (5), and ziegler (6). the present review will restrict itself to the recent work on chemotaxis in escherichia coli and salmonella typhimurium. some of this is al ... | 1976 | 772314 |
| studies of bacterial chemotaxis in defined concentration gradients. a model for chemotaxis toward l-serine. | the details of the chemotactic response of salmonella typhimurium to gradients of l-serine have been examined in some detail. two relatively macroscopic techniques have been employed to measure the bacterial response. these include measurements of the average velocity as the bacterial population moves toward attractants, and measurement of the upward-to-downward flux ratio, r, in the stable preformed attractant gradients. the dependence of the average velocity on gradient appears to be hyperboli ... | 1976 | 772315 |
| the synthesis of s-adenosylmethionine by mutants with defects in s-adenosylmethionine synthetase. | some metk mutants of salmonella typhimurium with constitutive methionine biosynthesis have no detectable s-adenosylmethionine (sam) synthetase, the enzyme which converts methionine to sam, the postulated corepressor of the methionine pathway. however, these mutants are not auxotrophic for sam, an essential compound for many reactions. | 1976 | 772417 |
| [colitis due to salmonella typhimurium]. | | 1975 | 772880 |
| [mutagenicity testing of irradiated laboratory animal food in the host-mediated assay with salmonella typhimurium ta 1530]. | | 1976 | 773051 |
| [study of mutants of salmonella typhimurium with altered sensitivity to the antibiotic fusidin]. | s. typhimurium mutants with altered sensitivity to fusidic acid (more resistant or more sensitive than the original culture) were selected. the mutants studied changed some of their properties (morphology, antigenic structure, and biochemical activity). they were characterized by a lower growth rate and probably by some alterations in the envelope cell structures- some mutants acquired cross resistance or sensitivity to other antibiotics. as the mutants were selected by increased resistance or s ... | 1976 | 773059 |
| in vitro and in vivo transfer of drug resistance for salmonella and escherichia coli strains in turkeys. | in vitro and in vivo transfers of antibiotic drug resistance were observed when isolates of multi-resistant salmonella saint-paul and escherichia coli donors were mated with multi-sensitive e coli and salmonella typhimurium recipients, respectively. for in vivo studies, day-old turkey poults were used. drug resistances were transferred either alone or in various combinations. in vitro, transfer was more frequent from e coli to s typhimurium; in vivo, transfer was more often observed from s saint ... | 1976 | 773224 |
| synergy in the antimicrobial action of penicillin and beta-chloro-d-alanine in vitro. | beta-chloro-d-alanine and penicillin g acted on early and late steps, respectively, in the biosynthesis of the bacterial cell wall. in combination these compounds showed a synergistic effect on the growth of salmonella typhimurium and of escherichia coli in vitro. | 1976 | 773296 |
| toxicity and mutagenicity of 2,4,-6-trinitrotoluene and its microbial metabolites. | tnt (2,4,6-trinitrotoluene) of explosive grade is highly toxic to marine forms that included fresh water unicellular green algae (selenastrum capricornutum), tidepool copepods (tigriopus californicus), and oyster larvae (crassostrea gigas), and mutagenic to salmonella typhimurium. on the basis of mutagenic assays carried out with a set of histidine-requiring strains of the bacterium, tnt was detected as a frameshift mutagen that significantly accelerates the reversion rate of a frameshift tester ... | 1976 | 773306 |
| mutants of salmonella typhimurium deficient in dna polymerase i: further characterization and genetic analysis. | tests with a plasmid-borne ochre suppressor (sup-812) and a chromosomal amber suppressor (supd501) revealed that one of three mutants of s. typhimurium deficient in dna polymerase i was an amber mutant. assays performed on crude extracts established that derivatives of this mutant (designated pola3) carrying ochre and amber suppressors had about 13 to 20% respectively of the enzyme activity found in the wild-type parent. the unsuppressed mutant showed less than 1% of the wild-type level of activ ... | 1975 | 773359 |
| a reaction mechanism from steady state kinetic studies for o-acetylserine sulfhydrylase from salmonella typhimurium lt-2. | it has been determined from steady state kinetic studies using the sulfide ion selective electrode that o-acetylserine sulfhydrylase catalyzes a bi bi ping pong reaction between o-acetyl-l-serine and sulfide. both o-acetyl-l-serine (oas) and sulfide exhibit strong competitive substrate inhibition. a fit of all the data to the equation for the mechanism yields koas = 0.149 +/- 0.059 mm and kioas = 46.91 +/- 10.06 mm for o-acetyl-l-serine and ks2- = 0.066 +/- 0.004 mm and kis2- = 0.013 +/- 0.006 m ... | 1976 | 773932 |
| outer membrane of salmonella. isolation of protein complex that produces transmembrane channels. | salmonella typhimurium outer membrane protein complexes can be reconstituted with lipopolysaccharide and phospholipids into membrane vesicles. these vesicles are permeable to a variety of low molecular weight compounds, but not to oligo- and polysaccharides of molecular weight higher than 700. a protein complex participating in selective membrane permeability can be isolated by gel filtration in the presence of sodium dodecyl sulfate. the active fractions contain three major protein species. the ... | 1976 | 773934 |
| relation between salmonella typhimurium biotypes and drug resistance, teheran, iran (1962-1973). | according to the procedure of cordano (1971), the identification of biotypes of 118 strains of salmonella typhimurium isolated from stools or rectal swabs of patients with sporadic cases of diarrhoea on the central plateau during the period 1962-1973 revealed that: from 118 s. typhimurium, 65 (55-1%) were biotype "d", 50 (42-4%) were "a" and three (2-5%) were "b". the predominant biotype was "d", followed by the "a" biotype, and "b" was rarely encountered. biotype "d" has existed since 1965, and ... | 1976 | 775118 |
| site c27 in phage p22 and control of the pathway to lysogeny. | phage p22 mutation c27 defines a site required for establishment , but not maintenance of repressor synthesis. this study confirms that p22 c27 is able to synthesize repressor if active repressor is present. an interaction involving gene products of c1 and c3 and the site c27 retards expression of the lytic genes of p22. mutations in gene c1 eliminate the retardation of lytic gene expression, but c27 does not alleviate the retardation. these results are used to construct a model that postulates ... | 1976 | 775292 |
| occurrence of a regulatory deficiency in purine biosynthesis among pur a mutants of salmonella typhimurium. | a defect in the repression of the de novo purine biosynthetic enzymes was detected among pura mutants of salmonella typhimurium. we suggest that the defect is caused by an altered purine regulation gene (purr) which affects the response level of at least five of the de novo enzymes to repression by excess adenine. thus the unlinked genes controlling these enzymes constitute a regulation controlled wholly or in part by a purr gene product. the regulation of the guanine operon is regulated by some ... | 1976 | 775307 |
| reaction of nitrosamines in the udenfriend system: principal products and biological activity. | reaction of diethylnitrosamine in the non-enzymatic, ascorbic acid-dependent, hydroxylating system of udenfriend yielded n-nitroso-2-(ethylamino)-ethanol as the major product extracted into methylene chloride. the major product derived from nitrosopiperidine in the same system was n-nitroso-4-piperidone. these products, however, were mutagenic to salmonella typhimurium ta 1535 only when activated by a rat liver microsomal preparation. | 1976 | 775321 |
| suppression of dimethylnitrosamine mutagenicity by nitrososarcosine and other nitrosamines. | nitrososarcosine, not mutagenic itself in the host-mediated assay using salmonella typhimurium g46 as indicator organism, lowered the mutant frequency produced by dimethylnitrosamine (dmn). mutant frequency was significantly depressed when 1.0 g/kg nitrososarcosine was administered by gavage 0.5--2.0 h prior to intramuscular injection of 500 mg/kg dmn. doses of nitrososarcosine as low as 37.2 mg/kg administered 45 min prior to dimethylnitrosamine treatment produced statistically significant redu ... | 1976 | 775326 |
| salmonellosis in calves due to lactose fermenting salmonella typhimurium. | a lactose fermenting strain of salmonella typhimurium was isolated from two calves which died during an outbreak of acute enteritis. the organism was biochemically typical in all other respects. in one calf, uncomplicated by treatment before death, the autopsy findings were those of a severe fibrinous enteritis which was reproduced in another calf dosed orally with culture. attention is drawn to scattered reports of lactose fermenting salmonelle causing morbidity and mortality in calves and man. | 1976 | 775752 |
| effect of lincomycin on prevalence, duration, and quantity of salmonella typhimurium excreted by swine. | thirty-one swine (7.5 kg live wt) were fed diets which contained 0 or 110 mg of lincomycin/kg. these pigs were then inoculated with a nalidixic acid-resistant strain of salmonella typhimurium and monitored for 56 days thereafter to determine (1) the quantity of s typhimurium shed in the feces, (2) the length of time the organism was shed, and (3) the number of swine which shed the organism for the 56-day period after exposure. addition of lincomycin to diets did not alter these 3 criteria from t ... | 1976 | 776049 |
| histidyl-transfer-ribonucleic-acid synthetase from salmonella typhimurium. studies of the sulfhydryl groups. | the reactivity of the sulfhydryl groups of histidyl-t rna synthetase from salmonella typhimurium and the effect of substrates on the reactivity has been studied using p-hydroxymercuribenzoate and 5, 5'-dithiobis (2-nitrobenzoic acid) as reagents. it has been found that 5, 5'-dithiobis (2-nitrobenzoic acid) titrates only two sulfhydryl groups per molcule of enzyme and the reaction is essenaitlly monophasic, while p-hydroxymercuribenzoate titrates four sulhydryl groups. as observed kinetically the ... | 1976 | 776625 |
| evidence that ht mutant strains of bacteriophage p22 retain an altered form of substrate specificity in the formation of transducing particles in salmonella typhimurium. | | 1976 | 776744 |
| the association of tryptophan synthetase subunits from escherichia coli and salmonella typhimurium in homologous and heterologous combinations. | | 1976 | 776745 |
| evidence for an extrinsic immunogen in effective ribosomal vaccines from salmonella typhimurium. | previous work has indicated that ribosomes isolated from salmonella typhimurium were highly immunogenic and afforded excellent protection against homologous challenge. effective protection was obtained also when ribonucleic acid ( rna) extracted from these ribosomes was used as a vaccine. in this investigation ribosomes prepared by another method and washed repeatedly in 1 m nh1cl lost much of their prophylactic potency and yielded poorly protective rna. the high-salt wash of the ribosomes was i ... | 1976 | 776831 |
| salmonella typhimurium sa host specificity system is based on deoxyribonucleic acid-adenine methylation. | we have determined the nature of the deoxyribonucleic acid (dna) modification governed by the sa host specificity system of salmonella typhimurium. two lines of evidence indicate that sa modification is based on methylation of dna-adenine residues. (i) the sa+ locus of salmonella was transferred into escherichia coli b, a strain that does not contain 5-methylcytosine in its dna; although the hybrid strain was able to confer sa modification, its dna still did not contain 5-methylcytosine. (ii) th ... | 1976 | 776925 |
| mutants of salmonella typhimurium deficient in an endoprotease. | three bands of hydrolytic activity toward the chromogenic protease substrate n-acetyl-dl-phenylalanine beta-naphthyl ester (napne) can be observed after gel electrophoresis of crude extracts of salmonella typhimurium or escherichia coli. mutants deficient in one of these three activities have been isolated using a staining procedure that identifies colonies that show reduced ability to hydrolyze napne. these mutants lack the strongest of the three bands of activity. the salmonella mutations (des ... | 1976 | 776937 |
| genetic and physiological regulation of intrinsic proteins of the outer membrane of salmonella typhimurium. | four major outer membrane polypeptides, accounting for approximately 20% of the total protein of the outer membrane of salmonella typhimurium, were induced by growth in minimal medium. the polypeptides were tightly bound membrane components. physiological and genetic evidence indicates that the four polypeptides fall in two separate regulation groups. synthesis of one of these groups was coordinately regulated by the concentration of iron in the medium, and a mutant strain has been identified in ... | 1976 | 776938 |
| comparative study of r1-specific chromosomal transfer in escherichia coli k-12 and salmonella typhimurium lt2. | high-frequency transfer of the chromosomal trp region by r1 observed in escherichia coli (pearce and meynell, 1968) also occurs in salmonella typhimurium. the reaction is reca independent in both species. the origin of transfer lies within a segment of the chromosome that is inverted in s. typhimurium relative to e. coli, and thus transfer occurs in a different direction in the two species. the character of r1 that is responsible, known as tfa+, may be lost without affecting other properties of ... | 1976 | 776939 |
| partial characterization of nucleoids and nucleoid-plasmid complexes from salmonella typhimurium. | nucleoids from salmonella typhimurium strain lt2 consist of supercoiled deoxyribonucleic acid structures that are ribonuclease labile sedimenting at 1,700s. more than 90% of the covalently closed circular deoxyribonucleic acid of a cryptic plasmid harbored by this strain cosediments with the host's 1,700s nucleoids. | 1976 | 776947 |
| biosynthesis of riboflavin. structure of the purine precursor and origin of the ribityl side chain. | we studied the incorporation of 14c-labeled guanosine into riboflavin under conditions precluding the metabolic conversion of guanosine compounds to free guanine. for this purpose we isolated a mutant bm 2 of salmonella typhimurium deficient in the enzymes imp dehydrogenase, purine nucleoside phosphorylase, and purine nucleotide pyrophosphorylase. the mutant incorporated [ribose-14c]guanosine into riboflavin and gmp without dilution. the isolated compounds were exclusively labeled in the ribityl ... | 1976 | 776973 |
| purification and properties of the alpha2beta2 complex of tryptophan synthetase of proteus mirabilis. | a procedure is described for the purification of the tryptophan synthetase alpha2beta2 complex from cell extracts of proteus mirabilis. a 30-fold purification was achieved with an overall yield of about 23% and a specific activity of 1,600. the complex can be dissociated and the subunits isolated in a pure form. the complex can be reconstituted from the isolated subunits to regain the initial activity. the alpha and beta2 subunits of the tryptophan synthetase complex of p. mirabilis are not sign ... | 1976 | 776977 |
| failure to detect a mutagenic activity of 8-methoxypsoralen (in the dark) in strains of salmonella typhimurium and escherichia coli. | | 1976 | 778608 |
| lack of mutagenic activity in salmonella typhimurium of four optical brighteners. | | 1976 | 778609 |
| induction of point mutations by different chemical mechanisms in the liver microsomal assay. | a selection of chemical agents with different mechanisms of chemical mutability was tested with the liver microsomal assay by using different bacterial tester strains, namely: salmonella typhimurium ta 1535, ta 1536, ta 1537, ta 1538 and g46. the tested agents had been selected according to the following criteria. they are all well-known mutagens and can be divided into alkylating agents, anti-metabolites, acridines and those that form radicals in the cell. the mutagens were: dimethylnitrosamine ... | 1976 | 778610 |
| [case of meningitis due tp salmonella typhimurium]. | | 1975 | 778776 |
| protein-protein interaction in transport: periplasmic histidine-binding protein j interacts with p protein. | a component of the high-affinity histidine transport system in salmonella typhimurium, the periplasmic histidine-binding protein j, interacts with another transport component, the p protein. a mutant j protein, with a defective interaction site but intact histidine-binding site, can function in histidine transport if an appropriate compensating mutation is introduced in the p protein. the interaction between the j and p proteins is an obligatory step in transport. the significance of this intera ... | 1976 | 778848 |
| morphogenesis of the bacterial division septum: a new class of septation-defective mutants. | a new class of mutants of salmonella typhimurium (lkyd mutants) are described. the mutants are defective in morphogenesis of the division septum, and are characterized by a failure of the outer membrane to invaginate despite normal ingrowth of the cytoplasmic membrane and murein layers of the growing septum. the cell envelopes of the mutants show a significant decrease in the bound form of murein-lipoprotein and a corresponding increase in the free form of the lipoprotein. this suggests that the ... | 1976 | 778849 |
| [mutagenic activity of benzonal]. | benzonalum mutagenic activity was demonstrated in a dominant lethal test on mice. the late spermatids stage proved to be the most sensitive in this respect. the benzonalum did not evoke any cytogenetic activity, that was shown by counting chromosome aberrations in metaphases of the bone marrow cells in vivo and did not induce gene mutations in tester trains of salmonella typhimurium in vitro and in vivo (a host-mediated assay). | 1976 | 779185 |
| genetic properties of rm 98, an r plasmid of salmonella which determines sensitivity to the phage ike. | an r plasmid of salmonella, rm98, which determines sensitivity ot the phage ike (ikes) and confers resistance to ampicillin (ap), streptomycin (sm) and tetracycline (tc) was studied for its genetic properties in salmonella typhimurium and escherichia coli, transduction of rm98 by p22 in salmonella yielded transductants of which some had acquired all the recognizable markers (ap, sm, tc, ikes and resistance transfer factor or rtf) associated with rm98. this transduction pattern resembles the p22 ... | 1976 | 779352 |
| [resistance to beta-lactam antibiotics and aminoglycosides in gram negative bacteria. 1. molecular and genetic characterization of r-factors (author's transl)]. | with frequent use of aminoglycoside antimicrobials and beta-lactam antibiotics in hospitals in the last few years, the number of bacterial strains resistant to these chemotherapeutics increased. lately, strains of e. coli, klebsiella, enterobacter, serratia, proteus and pseudomonas resistant to many antimicrobials (ampicillin, carbenicillin, cephalothin, chloramphenicol, gentamycin, tobramycin, sisomycin, neomycin, paromomycin, kanamycin, streptomycin, spectinomycin, tetracycline, sulphonamides) ... | 1976 | 779353 |
| influence of antibiotic-supplemented feed on occurrence and persistence of salmonella typhimurium in experimentally infected swine. | the effect of chlortetracycline given at a concentration of 220.5 g/metric ton of feed and of a combination product which supplies chlortetracycline (110.2 g/metric ton), sulfamethazine (110.2 g/metric ton), and penicilin g (55.1 g/metric ton) on the occurrence and persistence of salmonella typhimurium in experimentally infected swine was studied. weanling pigs (av weight, 8.2 kg) were inoculated via the feed with 10(11) colony-forming units of s typhimurium 298-1na. an equal number of nonexpose ... | 1976 | 779539 |
| the biosynthesis of the thiazole moiety of thiamine in salmonella typhimurium. | the mechanism of biosynthesis of 4-methyl-5-beta-hydroxyethyl thiazole, the thiazole moiety of thiamine was studied in salmonella typhimurium. using the adenosine derepression technique the incorporation of various 14c-labeled precursors was determined. we found that;e1me-14c]methionine, [2-14c]methionine, [u-14c]alanine, and [2-14c]glycine were not incorporated whereas [2-14c]tyrosine was incorporated. degradation of the 4-methyl-5-beta-hydroxyethyl thiazole obtained after [2-14c]tyrosine incor ... | 1976 | 779848 |
| a heterologous system for detecting eukaryotic enzymes which synthesize pseudouridine in transfer ribonucleic acids. | trna pseudouridylation activities have been detected in embryonic mouse cell fractions and in extracts from hela, mouse l-cell and baby hamster kidney (bhk) cell lines. these activities were identified by the use of heterologous reaction systems, with trna from hist strains of salmonella typhimurium as substrate. hist mutants are defective for an enzyme that forms psi residues in the anticodon region of many trnas and accumulate undermodified species of trna. the pseudouridylation activity from ... | 1976 | 780353 |
| decreased virulence of chlorate-resistant salmonella typhimurium. | | 1976 | 781146 |
| porphobilinogen-accumulating mutants of salmonella typhimurium lt2. | four independent porphobilinogen-accumulating mutants of salmonella typhimurium lt2 were isolated by selecting for dwarf colony formation on neomycin agar media. cell-free extracts of the parent strain, but not of the mutants, were able to convert 5-aminolaevulinic acid or porphobilinogen to porphyrins. the results indicated that the mutants were deficient in uroporphyrinogen i synthase (ec. 4.3.i. 8) activity: these are the first mutants of this type reported in s. typhimurium lt2. mapping of t ... | 1976 | 781181 |
| enhancement of base pair substitution induced by alkylating mutagens in simulated hyperbaric diving environments. | the effect of simulated saturated diving environments on mutagenicity was investigated using two histidine auxotrophs (hisg46 and hista1950 derived by ames from salmonella typhimurium lt2) exposed to several chemical mutagens. in agar diffusion tests with impregnated paper discs, 68 atm of normoxic supporting gases (containing 0.2 atm o2) reduced the number of histidine revertants of auxotrophs exposed to n-methyl-n'-nitro-n-nitrosoguanidine (ntg) and two other alkylating agents. the effect was ... | 1976 | 781534 |
| effects on body temperature produced by micro-injection of salmonella typhimurium lipopolysaccharide into the third cerebral ventricle of the chicken. | salmonella typhimurium lipopolysaccharide was injected into the third cerebral ventricle of the hen via a surgically implanted cannula. hens injected with 20-80 mug. salmonella typhimurium lipopolysaccharide had higher (p less than .01) rectal temperatures (42.3 degrees c. compared to 41.3 degrees c.) than uninjected hens. those injected with 0.9% nacl had significantly lower (p less than .01) rectal temperatures (41.8 degrees c. compared to 42.3 degrees c.) than hens injected with this bacteria ... | 1976 | 781654 |
| the effect of ultraviolet light on the frequency of a genetic duplication in salmonella typhimurium. | | 1976 | 781718 |
| [biological properties of salmonella typhimurium mutants with an altered sensitivity to erythromycin]. | s. typhimurium mutants with altered sensitivity to erythromycin (more resistant or more sensitive than the original culture) were selected. some of the properties of the mutants studied were found to be changed: morphology, character of growth in the liquid nutrient medium with aeration (increased generation time and number of generations in log-period), sensitivity to ionic detergent--sodium dodecyl sulfate (its decrease). some of the mutants acquired cross resistance or sensitivity to other an ... | 1976 | 782116 |
| the effect of t and b lymphocyte depletion on the protection of mice vaccinated with a gal e mutant of salmonella typhimurium. | immunosuppressive agents were used to determine the relative importance of t and b lymphocytes in conferring protection to mice vaccinated with a live gal e mutant of salmonella typhimurium, strain g30d. lymphocyte transformation and serum agglutination tests showed that while cyclophosphamide (cpa) suppressed b lymphocytes, antilymphocyte sea (als) suppressed both t and b cells. the humoral response of vaccinated animals treated with als was therefore supplemented by the i.v. injection of serum ... | 1976 | 782501 |
| anthranilate synthase-anthranilate 5-phosphoribosylpyrophosphate phosphoribosyltransferases from salmonella typhimurium. purification of the enzyme complex and analysis of multiple forms. | 1. the anthranilate synthase-anthranilate 5-phosphoribosylpyrophosphate phosphoribosyltransferase enzyme complex (chorismate pyruvatelyase (amino-accepting), ec 4.1.3.27) - (n-(5'-phosphoribosyl)-anthranilate: pyrophosphate phosphoribosyltransferase, ec 2.4.2.18), from salmonella typhimurium has been purified with high yields to homogeneity. sodium dodecyl sulfate gel electrophoresis of the purified enzyme complex revealed one major band containing 96% of the protein. the final yield of enzyme c ... | 1976 | 782548 |
| metal ion requirement and tryptophan inhibition of normal and variant anthranilate synthase-anthranilate 5-phosphoribosylpyrophosphate phosphoribosyltransferase complexes from salmonella tyrhimrium. | 1. both mn2+ and co2+ can replace mg2+ as the required divalent cation for all activities of the enzyme complex between anthranilate synthase (chorismate pyruvate-lyase (amino-accepting), ec 4.1.3.27) and anthranilate-5-phosphoribosylpyrophosphate phosphoribosyltransferase (n(5'-phosphoribosyl)-anthranilate:pyrophosphate phosphoribosytransferase, ec 2.4.2.18) from salmonella typhimurium. they have much lower apparent km values than mg2+, both for glutamine-dependent anthranilate synthase (mn2+ = ... | 1976 | 782549 |
| detection of mutagenic activity in human urine using mutant strains of salmonella typhimurium. | histidine-requiring mutants of salmonella typhimurium that can be reverted to prototrophy by a variety of mutagens were used mutagenic activity in the urine of patients receiving chemotherapeutic agents. patients given cyclophosphamide and bcnu had detectable urinary mutagenic activity over a 24-hour period, with maximal levels occurring 12 to 21 hours after drug injection. whereas native cyclophosphamide required the presence of a rat liver extract to be mutagenic in the test system, the cyclop ... | 1976 | 782687 |
| compared efficiency of a killed vaccine of salmonella typhimurium, a live vaccine and an antigenic fraction in oral immunization of mice. | in an attempt to determine the best method of immunizing mice by oral route against salmonella typhimurium, the animals were vaccinated by means of a killed-pathogenic strain, an avirulent mutant of the same bacteria, and a protective antigen removed from the supernatant culture of this mutant. after changing doses of vaccines and the interval between vaccination and challenge, the results obtained show the superiority of the live vaccine and protective antigen with regard to the killed one. und ... | 1976 | 782961 |
| vaccination against typhoid fever with a live oral vaccine. | a salmonella typhi gal e mutant, designated ty 21a, has been developed on the basis of virulence and protection studies with similar salmonella typhimurium mutants in mice. gal e mutants are characterized by a block in the enzyme udp-4-galactose-epimerase. they owe their outstanding immunizing capacity when used in live oral vaccine to the fact that when galactose is supplied exogenously, as occurs in vivo, wild-type cell wall structures are synthesized. on the other hand, avirulence of these m ... | 1976 | 782975 |
| specialized transduction by bacteriophage p22 in salmonella typhimurium: genetic and physical structure of the transducing genomes and the prophage attachment site. | p22pro-1 and p22pro-3 are specialized transducing derivatives of phage p22 that carry the proa and prob genes of salmonella typhimurium. these genes lie immediately adjacent to the prophage attachment site on the bacterial chromosome. by examining dna heteroduplexes in the electron microscope, we found that dna molecules from p22pro-1 and p22pro-3 each contain a substitution which adds length to the composite genome making the intracellular replicated genome too long to fit into a single phage p ... | 1976 | 783004 |
| specialized transducing phages derived from phage p22 that carry the pro ab region of the host, salmonella typhimurium: genetic evidence for their structure and mode of transduction. | two independently isolated specialized transducing phages, p22pro-1 and p22pro-3, have been studied. lysates of p22pro-1 contain a majority of transducing phages which can go through the lytic cycle only in mixed infection; these defective phages transduce by lysogenization in mixed infection and by substitution in single infection. a few of the transducing phages in p22pro-1 lysates appear to be non-defective, being able to form plaques and to transduce by lysogenization in single infection. tr ... | 1976 | 783005 |
| gradient elution of salmonella typhimurium and escherichia coli strains from a deae-cellulose column. | | 1976 | 783107 |
| iron transport in salmonella typhimurium lt-2: prevention, by ferrichrome, of adsorption of bacteriophages es18 and es18.h1 to a common cell envelope receptor. | ferrichrome prevents adsorption of phages es18 and es18.h1 to cells of salmonella typhimurium. studies of albomycin-resistant mutants defective in both ferrichrome utilization and es18.h1 adsorption suggest a sid gene may specify a receptor for both. | 1976 | 783114 |
| bacteriophage-resistant mutants of salmonella typhimurium deficient in two major outer membrane proteins. | mutants resistant to bacteriophages (p221 and ph105 or ph51) were isolated from a rfa strain of salmonella typhimurium. they were found deficient in separate 33,000- to 36,000-dalton band proteins (major band proteins). double mutants derived from both types of mutants were deficient in both of the bands. the growth behavior of all the mutants was normal. the outer membrane of the mutants appeared to be more wrinkled than normal and formed vesicles in many of the mutants. in freeze-fractured cel ... | 1976 | 783123 |
| enterobacterial common antigen in rfb deletion mutants of salmonella typhimurium. | the his-rfb deletion series of salmonella typhimurium mutants characterized previously by nikaido et al. was examined for the presence of the enterobacterial common antigen (eca). all deletions not extending further to the left than the genes for cytidine phosphoabequose synthesis were eca positive, whereas longer deletions (extending to the genes for thymidine diphosphorhamnose synthesis or further) were eca negative. when these long-his-rfb deletion strains were studied further, it became clea ... | 1976 | 783131 |
| temperature-sensitive ribonucleic acid polymerase mutant of salmonella typhimurium with a defect in the beta' subunit. | localized mutagenes of salmonella typhimurium followed by a [3h]uridine enrichment procedure yielded a temperature-sensitive strain with a mutation in the rpo region of the chromosome. ribonucleic acid (rna) polymerase (ec 2.7.7.6; nucleoside triphosphate: rna nucleotidyltransferase) purified from this mutant was considerably less active at the nonpermissive temperature than wild-type enzyme. furthermore, the enzyme from this mutant, unlike rna polymerase of previously isolated temperature-sensi ... | 1976 | 783138 |
| interference with propagation of typing bacteriophages by extrachromosomal elements in salmonella typhimurium: bacteriophage type 505. | samonella typhimurium bacteriophage type 505 is the most frequently encountered phage type in the netherlands and its neighboring countries. phage type 505 was analyzed with regard o the interference with propagation of the typing phages by the prophages and plasmids, present in the type strain s. typhimurium 505... | 1976 | 783145 |
| oligopeptide transport in proline peptidase mutants of salmonella typhimurium. | investigations of peptide transport in salmonella typhimurium are presented. a strain designated prob25, a proline auxotroph, grew on a variety of di, tri-, and tetrapeptides containing proline. in contrast (pro)6, peptides acylated on the nh2 terminus and ala-pro-d-ala did not satisfy the nutritional requirement of prob25 for proline because they were not transported. a derivative of prob25, strain tn87, deficient in a proline aminopeptidase and an x-pro dipeptidase, was able to utilize only fo ... | 1976 | 783159 |
| dna restriction and modification systems in salmonella. sq, a new system derived by recombination between the sb system of salmonella typhimurium and the sp system of salmonella potsdam. | as the result of p1-mediated cotransduction with serb from salmonella potsdam to the escherichia coli/salmonella typhimurium hybird 4617, one recombinant, l4004, was isolated which had a restriction-modification (r--m) system different from the sb and sp systems of its parents, and was designated sq. the genes of sq were allelic to those of the sb system of s. typhimurium and were shown by complementation experiments to be functionally related to those of the k system of e. coli. evidence that t ... | 1976 | 784901 |
| identification of nonsense mutations in the cysj gene of salmonella typhimurium. | | 1976 | 784904 |
| large overlapping tandem genetic duplications in salmonella typhimurium. | | 1976 | 785006 |
| genetic characterization of a phi80 transducing bacteriophage carrying the histidine operon of salmonella typhimurium. | a phi 80 transducing phage, phi 80imm lambdadhis, carrying the salmonella his-gnd region, was characterized by immunity studies, tonb deletion analysis, and marker rescue analysis. phi 80imm lambdadhis retains the phage immunity region of the phi 80-lambda hybrid phage from which it was derived. bacterial genes replace most late phage genes. deletion analysis shows the prophage gene order to be immlambda-his-gnd and indicates the orientation of the his operon to be hisogdcbhafie-gnd. the structu ... | 1976 | 785022 |
| a recombination-dependent replicating instability in salmonella typhimurium. | the aromatic amino acid-requiring mutant of salmonella typhimurium arod321 has a stable requirement for phenylalanine and tyrosine but is highly unstable in its requirement for tryptophan. tryptophan requiring cells derived from this strain are themselves unstable and revert back to a requirement for only phenylalanine and tyrosine. this instability is cotransducible with the arod region and is totally dependent on the presence of a rec+ gene in the cell. these observations are interpreted in te ... | 1976 | 785244 |
| mutagenicity and toxicity of amitrole. iii. microbial tests. | amitrole (3-amino-1,2,4-triazole) inhibits bacterial growth both in escherichia coli and salmonella typhimurium at a concentration of 0.5% in minimal medium. repression of growth already occurs at a concentration of 0.1% of amitrole in this medium. in complete medium the bacteria tolerate concentrations of amitrole as high as 1.7-2.4% before growth ceases. mutagenicity was tested by differential growth comparisons on e. coli strains w 3110 thy pol a1, defective in dna polymerase i, and its rever ... | 1976 | 785246 |
| mutagenesis by 9,10-anthraquinone derivatives and related compounds in salmonella typhimurium. | ninety 9,10-anthraquinone (aq) derivatives and related anthracene derivatives were screened for mutagenicity with five salmonella typhimurium tester strains with and without mammalian microsomal activation. about 35% of the compounds tested are considered to be mutagenic. three patterns of mutagenesis were apparent. (1)direct frameshift mutagenesis by certain aq compounds bearing free hydroxyl groups. the most potent were anthragallol (1,2,3-trihydroxy-aq), purpurin (1,2,4-trihydroxy-aq) and ant ... | 1976 | 785247 |
| bacteriophage p22 lysogenises efficiently at high multiplicities of infection because salmonella typhimurium dna synthetic capacity is limited. | | 1976 | 785285 |
| [salmonella bacteria in double cream (author's transl)]. | in june 1974 a serious outbreak salmonellosis was reported from the southeast of sweden. the epidemic was caused by salmonella typhimurium and spread by infected cream, packed in one-way paper-plastic containers. ordinary pasteurization of cream purposely infected with the strain in question at 60 degrees for 38 sec or 67 degrees c for 4,5 sec, resulted in a reduction by more than 7 decimal logs (table i). the decimal reduction time at 60 degrees in cream was estimated to roughly 1.3 sec. the cr ... | 1976 | 785382 |
| [biochemical identification of salmonella and coli bacteria and their sensitivity to chemotherapeutic agents]. | strains of enterobacteria, isolated from pathologic material (dead pigs, birds, lambs, sheep fetuses, swab fecal samples from calves) were biochemically identified by the methods of costin, le minor, and eming. one-hundred forty of them proved to belong to escherichia coli and 236 -- to salmonella. the sensitivity of the isolated bacteria to antibiotics (ampicillin, streptomycin, tetracyclin, kanamycin, neomycin, chloramphenicol, erythromycin, oleandomycin polymyscin), sulfonamides (norsulfasol, ... | 1976 | 785798 |
| anatomical locus of the common enterobacterial antigen. | cell walls, membrane vesicles and the soluble cytoplasmic components have been isolated from escherichia coli 0:14 and salmonella typhimurium and examined by electron microscopy as well as hemagglutination inhibition with heterologous antisera for enterobacterial common antigen (eca). the outer and cytoplasmic membranes also were isolated and examined for common antigen. although common antigen was present in the isolated surface structures it was not localized exclusively in these fractions. ad ... | 1976 | 785849 |
| mutagenicity of volatile anesthetics: halothane. | the mutagenicity of halothane was tested in an in-vitro microbial assay system employing two histidine-dependent mutants of salmonella typhimurium, ta98 and ta100, halothane in concentrations ranging from 0.1 to 30 per cent was incubated with bacteria in the presence or absence of a metabolic activation system prepared from either rat liver treated with aroclor 1254 or human liver. trifluoroacetic acid, a major metabolite of halothane, and urine from patients anesthetized with halothane also wer ... | 1976 | 786079 |
| gene m3 mediated efflux of intracellular leucine from bacteriophage p22 infected salmonella typhimurium. | | 1976 | 786291 |
| mutagenic activity of carcinogenic and noncarcinogenic nitrofurans and of urine of rats fed these compounds. | the nitrofurans, 2-(2-furyl)-3-(5-nitro-2-furyl)acrylamide (af-2), n-[4-(5-nitro-2-furyl)-2-thiazolyl]formamide (fanft), nitrofurantoin, 5-nitro-2-furoic acid, 5-nitro-2-furamidoxime, 5-nitrofurfurylidene diacetate and the urine of rats fed these compounds, were assayed for mutagenic activity in salmonella typhimurium strains ta100 and ta100fr1. all the nitrofurans were mutagenic in the order: af-2 and fanft greater than nitrofurantoin greater than 5-nitro-2-furamidoxime greater than 5-nitrofurf ... | 1976 | 786488 |
| thialysine-resistant mutant of salmonella typhimurium with a lesion in the thra gene. | a mutant of salmonella typhimurium was selected for its spontaneous resistance to the lysine analog, thialysine (s-2-aminoethyl cysteine). this strain, jb585, exhibits a number of pleiotropic properties including a partial growth requirement for threonine, resistance to thiaisoleucine and azaleucine, excretion of lysine and valine, and inhibition of growth by methionine. genetic studies show that these properties are caused by a single mutation in the thra gene which encodes the threonine-contro ... | 1976 | 786777 |
| characterization of the virulence and antigenic structure of salmonella typhimurium strains with lipopolysaccharide core defects. | the virulence and antigenic characters of salmonella typhimurium strains, identical except for known lipopolysaccharide core defects, were compared. smooth strains multiplied extensively and killed most mice. deep rough strains containing only heptose i or heptose i and ii in the rough core were completely eliminated after 6 h, whereas more superficial rough strains containing additional core sugars could be detected in low numbers (10(4) colony-forming units/g of tissue) for at least 7 days pos ... | 1976 | 786875 |
| effect of enterobacterial common antigen on mouse virulence of salmonella typhimurium. | a series of nearly isogenic o4-12, and o-6,7 salmonella typhimurium strains differing in regard to the enterobacterial common antigen (eca) were constructed by conjugation. when tested in intraperitoneal infection of mice, the o-4,12 strains containing eca were more virulent than their o-4,12 sister recombinants without eca (p = less than 0.001). the same difference could be shown with eca-positive and eca-negative s. typhimurium derivatives, whose o antigens were of the group c type (o-6,7). th ... | 1976 | 786878 |
| variability of protection in inbred mice induced by a ribosomal vaccine prepared from salmonella typhimurium. | ribosomal vaccines prepared from salmonella typhimurium were effective immunogens in a/j inbred mice and c3h/hetex, inbred mice. however, ribosomal vaccines were not protective in c57bl/6j inbred mice. a/j mice were protected against lethal challenge by attenuated s. typhimurium live-cell, ribosomal, phenol, and heat-killed vaccines. c3h/hetex mice were protected by live-cell, ribosomal, and phenol vaccines but not the heat-killed vaccine. only the live-cell vaccine gave significant protection i ... | 1976 | 786889 |