| the aetiology of diarrhoea in pigs weaned at two days of age. | when pigs are weaned at two days of age large numbers of excherichia coli appear in the anterior gut and the incidence of diarrhoea rises. the two phenomena do not appear to be directly related because the strains of e coli isolated are not serotypes previously found to be associated with neonatal pig scouring. representative strains of the non-enteropathogenic serotypes did not produce enterotoxin and did not adhere to small intestine brush borders. moreover when antibiotics were fed to elimina ... | 1979 | 228367 |
| [presence of antibodies in human colostral secretory iga against enteric commensal bacteria: biological implications (author's transl)]. | antisecretory component, anti-alpha, anti-mu and anti-fc (gamma) fluorescent antibodies were used to detect the presence of immunoglobulins with antibody activity against enteric commensal bacteria in human colostrum and serum. forty nine colostrum samples were studied; all of them displayed secretory iga (siga) antibodies reacting with bacteroides thetaiotaomicron, clostridium perfringens and escherichia coli serotype o141:h32 without any k antigen. the amount of siga antibodies was always rela ... | 1979 | 228579 |
| enhancement of post-ultraviolet killing in escherichia coli k-12 through the action of gyrase inhibitors: evidence for associated gyrase-recbc deoxyribonuclease function. | this work in conjunction with the results presented in an earlier report (m. a. purdy and k. l. yielding, antimicrob. agents chemother. 10:182--184, 1976) showed the following. (i) nalidixic acid and novobiocin could inhibit post-ultraviolet and post-x-ray survival, implicating gyrase function in deoxyribonucleic acid repair. (ii) the inhibition of post-ultraviolet survival requires the action of functional recbc deoxyribonuclease. (iii) structural changes in the gyrase could (a) cause recbc mut ... | 1979 | 228590 |
| mecillinam-ampicillin synergism in experimental enterobacteriaceae meningitis. | the in vitro activities of mecillinam, a new beta-amidinopenicillin, and ampicillin, alone and in combination, against an escherichia coli strain and a klebsiella pneumoniae strain were compared, and these results were correlated with their respective activities in vivo in experimental meningitis. the mecillinam-ampicillin combination was synergistic in vitro against both strains when tested by a modified checkerboard technique (bacteriostatic synergy). however when quantitative bactericidal syn ... | 1979 | 228591 |
| in vivo enhancement of general and specific transcription in escherichia coli by dna gyrase activity. | the effect of drugs which inhibit dna gyrase, including nalidixic acid, oxolinic acid and coumerycin, on transcription of escherichia coli bacteria, phage and plasmid genomes was studied. quantitative estimates of the synthesis of rna under drug-treatment conditions showed that synthesis of many rna species, including trp mrna, was subject to inhibiton by the drug. transcription directed by the lambda promoter pr was selectively less sensitive to the drug action than transcription initiated at t ... | 1979 | 229056 |
| effects of subinhibitory amounts of ampicillin, amoxycillin and mecillinam on the adhesion of escherichia coli bacteria to human urinary tract epithelial cells: a preliminary study. | attachment to mucous surfaces may be a prerequisite for bacteria colonizing these surfaces or invading underlying tissues. subinhibitory amounts of ampicillin and amoxycillin but not mecillinam decreased the attachment of escherichia coli bacteria to human uro-epithelial cells in vitro. no significant synergistic effect on the attachment by the antibiotics was obtained. the present report indicates a new parameter for the study of antibacterial actions of drugs. | 1979 | 229079 |
| lethal effect of complement and lysozyme on polymyxin-treated, serum-resistant gram-negative bacilli. | when genetically serum-resistant escherichia coli, klebsiella pneumoniae, and citrobacter freundii, but not pseudomonas aeruginosa or proteus mirabilis, were exposed to polymyxin b, they became susceptible to the bactericidal action of normal human and rabbit sera. in constrast, beta-lactam and aminoglycoside antibiotics did not render any serum-resistant bacteria serum-sensitive. synergy between polymyxin b and the serum bactericidal system could be demonstrated by the addition of polymyxin b t ... | 1979 | 229175 |
| a small, unstable rna molecule of escherichia coli: spot 42 rna. ii. accumulation and distribution. | | 1979 | 229230 |
| fructose-1,6-diphosphatase: a cellular site of hyperbaric oxygen toxicity. | the growth-inhibitory effect of 4.2 atm of hyperbaric oxygen for escherichia coli was strongly influenced by available nutrients. a pattern of protection was achieved with various carbohydrate intermediates which was consistent with oxygen-induced poisoning of fructose-1,6-diphosphatase and of enzymes required in the pentose shunt and for converting galactose into glucose. two of these sites have not been investigated further, but direct evidence was obtained that purified fructose-1,6-diphospha ... | 1978 | 229387 |
| uridine diphosphate galactose 4-epimerase. alkylation of enzyme-bound diphosphopyridine nucleotide by p-(bromoacetamido)phenyl uridyl pyrophosphate, an active-site-directed irreversible inhibitor. | when udp-galactose 4-epimerase is inactivated by p-(bromoacetamido)phenyl uridyl pyrophosphate (bup), the diphosphopyridine nucleotide (dpn) associated with this enzyme as a tightly bound coenzyme cannot be reduced by substrates or by ump-activated reduction by glucose. upon acid denaturation of the inactivated enzyme, the dpn released corresponded to 15-30% of that released from the native enzyme. when the enzyme is inactivated by [14c]bup, about 80% of the radioactivity bound at the active sit ... | 1979 | 229891 |
| glutamyl transfer ribonucleic acid synthetase of escherichia coli. study of the interactions with its substrates. | the binding of the various substrates to escherichia coli glutamyl-trna synthetase has been investigated by using as experimental approaches the binding study under equilibrium conditions and the substrate-induced protection of the enzyme against its thermal inactivation. the results show that atp and trnaglu bind to the free enzyme, whereas glutamate binds only to an enzyme form to which glutamate-accepting trnaglu is associated. by use of modified e. coli trnasglu and heterologous trnasglu, a ... | 1979 | 229901 |
| glutamyl transfer ribonucleic acid synthetase of escherichia coli. effect of alteration of the 5-(methylaminomethyl)-2-thiouridine in the anticodon of glutamic acid transfer ribonucleic acid on the catalytic mechanism. | | 1979 | 229902 |
| failure to reverse cholera toxin induced intestinal secretion by agents which decrease mucosal camp. | the feasibility of reducing intestinal secretion by the use of agents which decrease intestinal mucosal camp concentration has been investigated in the weanling pig and the rabbit. three different agents for decreasing mucosal camp concentration were studied. the cyclic nucleotide phosphodiesterase activator, imidazole, significantly reduced mucosal camp concentrations only in the weanling pig. intraluminal 2'-deoxyadenosine-3'amp inhibited adenylate cyclase and caused a decrease in mucosal camp ... | 1979 | 229947 |
| on the pathogenicity of entamoeba histolytica. part i: the role of bacterial associate on the modification of virulence of e. histolytica. | of the 3 strains of escherichia coli used, only milner a strain was found capable of modifying the virulence of entamoeba histolytica. none out of twenty-four hamsters inoculated with either 5 x 10(5) of axenically-cultured e. histolytica of nih: 200 strain, or 1 x 10(7) of esch. coli (a, b or c strains), was found to have amebic liver abscess. whereas one out of six hamsters inoculated with the same number of amebae preincubated for 12 hrs with esch. coli of milner a strain was found to have ab ... | 1979 | 230014 |
| studies on a mutant form of escherichia coli citrate synthase desensitised to allosteric effectors. | naturally occurring citrate synthases fall into distinct molecular and catalytic types. gram-negative bacteria produce a 'large' enzyme, allosterically inhibited by nadh and, in the facultative anaerobes such as escherichia coli, also by 2-oxoglutarate. on the other hand, gram-positive bacteria and all eukaryotes produce a 'small' citrate synthase which is insensitive to these metabolites. as a complement to structure-function studies we have explored the possibility of genetically altering one ... | 1979 | 230033 |
| nucleic acid binding and unfolding properties of ribosomal protein s1 and the derivatives s1-f1 and m1-s1. | the nucleic acid binding and unwinding properties of wild-type escherichia coli ribosomal protein s1 have been compared to those of a mutant form and a large trypsin-resistant fragment, both reported recently [j. mol. biol. 127, 41-45 (1979) and j. biol. chem. 254, 4309-4312 (1979). the mutant (m1-s1) contains 77% and the fragment (s1-f1) 66% of the polypeptide chain length (approximately 600 amino acid residues) of protein s1. the mutant is active in protein synthesis in vitro; the fragment, al ... | 1979 | 230041 |
| construction and characterization of a recombinant plasmid encoding the gene for the thymidine kinase of herpes simplex type 1 virus. | we have constructed a hybrid plasmid by insertion of the thymidine kinase (tk) gene of herpes simplex virus (hsv) type i at the bamhi site on escherichia coli plasmid pbr322. the restriction endonuclease cleavage site map for the viral dna fragment was determined for ten nucleases, and the insert in the recombinant plasmid has the same restriction nuclease digestion pattern as bona fide viral dna. this result indicates that the plasmid contains an accurate copy of the viral dna. the viral tk gen ... | 1979 | 230124 |
| biosynthesis of phospholipids in bacillus megaterium. | information on the biosynthesis of phospholipids in bacteria has been derived principally from the study of escherichia coli and other gram-negative organisms. we have now carried out a detailed study of the pathways of phospholipid biosynthesis in the gram-positive organism bacillus megarterium km in relation to investigations on the biogenesis of lipid asymmetry in membranes. radioactive precursors such as 32pi and [3h]palmitate initially label phosphatidylethanolamine much more than phosphati ... | 1979 | 230180 |
| role of bacterial growth rates in the epidemiology and pathogenesis of urinary infections in women. | the mean minimum generation time in shake culture in urine of 6 urinary isolates of escherichia coli (21.7 +/- 0.6 min) was significantly shorter (p = 0.0003) than that of 14 isolates of less common urinary pathogens (46.0 +/- 18.6 min). mixed populations of approximately equal numbers of e. coli cells paired with other urinary, fecal, and urethral organisms were introduced into a laboratory model of the lower human urinary tract. this model used urine as a medium and reproduced some features of ... | 1979 | 230198 |
| involvement of cyclic amp and its receptor protein in the sensitivity of escherichia coli k 12 toward serine: excretion of 2-ketobutyrate, a precursor of isoleucine. | a relationship between serine-induced growth sensitivity and the camp-cap complex is established. mutants of escherichia coli k 12 deficient either in the cya or crp gene function exhibit a resistant phenotype on serine media although they harbor a rela allele normally leading to sensitivity toward serine. the presence of a crp allele in a cya delta rela background restores the sensitivity phenotype, while the analysis of serine resistant mutants selected from a crp cya delta rela strain shows t ... | 1979 | 230407 |
| the stimulation of escherichia coli stringent factor-dependent synthesis of guanosine 3',5'-polyphosphate [(p)ppgpp] by rat liver ribosomal proteins. | the effect of groups of proteins from rat liver ribosomes on the escherichia coli stringent factor-catalyzed synthesis of (p)ppgpp was tested. most groups were capable of supporting (p)ppgpp synthesis; the exceptions were a40, b140, b240 and b160 which contain proteins which are relatively less basic than those in the active groups. the capacity of 30 individual rat liver ribosomal proteins to activate stringent factor was assessed; most sustained the synthesis of (p)ppgpp. proteins s12, s21, l1 ... | 1979 | 230408 |
| control of minicell producing cell division by camp-receptor protein complex in escherichia coli. | it has been established that the strain ca8000 of escherichia coli k12 produces minicells. this phenotype of ca8000 has been shown to be suppressed by additional mutations in cya or crp genes. minicell production by cya+ crp+ min bacteria is probably a consequence of error, introduced by horizontal growth, in the selection of site on the envelope for initiation of hemispherical growth. | 1979 | 230409 |
| regulation of synthesis of a major outer membrane protein: cyclic amp represses escherichia coli protein iii synthesis. | cyclic amp is the effector molecule for both positive and negative control of synthesis of several escherichia coli proteins. among the latter is the major outer membrane protein iii. the control mechanism occurs at the level of transcription and involves the cyclic amp receptor protein. the repressing system is saturated at lower concentrations of cyclic amp than is the positive control system. | 1979 | 230479 |
| spliced adenovirus-associated virus rna. | we describe the structure of cytoplasmic rna species transcribed from the dna of adenovirus-associated virus, a defective parvovirus. the rna was hybridized with minus strand template dna and visualized in the electron microscope. alternatively, the dna.rna duplex molecules were digested with nuclease s1 or escherichia coli exonuclease vii and analyzed by agarose gel electrophoresis. a set of rna species was observed with 5' terminal at map positions 5, 13, 19, or 39 and a 3' terminus and poly(a ... | 1979 | 230481 |
| synthesis of simian virus 40 t antigen in escherichia coli. | plasmids are constructed by using recombination in vitro according to roberts, t.m., kacich, r. & ptashne, m. (1979) proc. natl. acad. sci. usa 76, 760-764 in which the t antigen gene of simian virus 40 is fused to a promoter of the escherichia coli lac operon. in the fusions, transcription commences at the lac promoter, and, in some of the fusions, translation begins at the atg initiator codon of the t gene. this translation is directed most efficiently by those plasmids in which the lac sequen ... | 1979 | 230483 |
| a topoisomerase from escherichia coli related to dna gyrase. | we have identified a topoisomerase activity from escherichia coli related to dna gyrase (topoisomerase ii): we designate it topoisomerase ii'. it was constructed of two subunits, which were purified separately. one is the product of the gyra (formerly nala) gene and is identical to subunit a of dna gyrase. the other is a 50,000-dalton protein, which we have purified to homogeneity and call v. v may be a processed form of the much larger gyrase subunit b or may be derived from a transcript of par ... | 1979 | 230498 |
| dna gyrase: purification and catalytic properties of a fragment of gyrase b protein. | a protein isolated from escherichia coli complements the dna gyrase a (nala) protein to generate an activity that relaxes supercoiled dna. oxolinic acid, a known inhibitor of dna gyrase, blocks this activity and causes double-strand cleavage of dna at the same sites as are attacked by dna gyrase. the protein, of molecular weight 50,000, appears to be fragment of the dna gyrase b (cou) protein (molecular weight, 90,000) as judged by the identical sizes of numerous peptides produced by partial pro ... | 1979 | 230505 |
| single-strand binding protein enhances fidelity of dna synthesis in vitro. | the effect of escherichia coli single-strand binding protein on the accuracy of in vitro dna synthesis has been determined by using two independent methods. by using the synthetic polynucleotide poly[d(a-t)] and measuring dgtp misincorporation or by using phi x174 dna and measuring nucleotide substitutions, we found that binding protein increases the fidelity of dna synthesis by as much as 10-fold. this increase is observed with dna polymerases of divergent sources and is progressive with increa ... | 1979 | 230506 |
| [clinical and bacteriological evaluation of sisomicin in sixteen cases of severe bronchopulmonary infection (author's transl)]. | sisomicin, an aminoglycoside antibiotic, was used as sole bactericidal therapy in sixteen cases of severe bronchopulmonary infection for an average of 11,5 days (range 7 to 14) with a dose of 3,5 mg/kg per day in three intramuscular injections. fifteen of these hospitalized patients presented with chronic airway obstruction which resulted in lowered o2 saturation (sao2 congruent to 86,1%, range 74 to 93) and, in twelve patients, hypercapnia (paco2 = 55,7 torr, range 33--73). two of these patient ... | 1979 | 230590 |
| r.smai cleavage map of the transfer region of the e. coli k12 sex factor f. | | 1979 | 230995 |
| evidence for the existence of three promoters for the deo operon of escherichia coli k12 in vitro. | | 1979 | 231107 |
| amplification of chloramphenicol resistance transposons carried by phage p1cm in escherichia coli. | we have characterized a number of p1cm phages which contain the resistance genes to chloramphenicol and fusidic acid as is1-flanked cm transposons. restriction cleavage and electron microscopic analysis showed that these cm transposons were carried as monomers (m) or tandem dimers (d). lysogens of p1cm (d) are more resistant to chloramphenicol than those of its p1cm (m) presumably as a result of an increased gene dosage. amplification of the cm transposons to tandem multimers was frequently obse ... | 1979 | 231182 |
| [phosphohydrolase activity of pseudomonas maltophilia]. | the activity of phosphohydrolase (acid, alkaline, pyrophosphatase) was studied in two strains of pseudomonas maltophilia: vcm-b-591 and sse-b-715. the activity of these enzyme systems in these strains was found to be much higher than in other pseudomonas species, viz. ps. aeruginosa vcm-b-889, ps. fluorescens vcm-b-553, ps. geniculata sse-b-338, and in e. coli b. the phosphohydrolase activity of ps. maltophilia varied depending on the growth phase of the culture. the highest activity of acid pho ... | 1979 | 231188 |
| temperature-sensitive 6-aminopenicillanic acid-resistant mutants of escherichia coli. | wild-type escherichia coli cells became spherical in the presence of low concentrations of 6-aminopenicillanic acid (apa). higher concentrations of apa caused inhibition of cell division (filamentation) and lysis. spontaneous temperature-sensitive apa-resistant mutants were isolated and characterized. these mutants also possessed increased resistance to mecillinam but not to benzylpenicillin, ampicillin, and cephaloridine. they formed round or pleomorphic cells at the nonpermissive temperature a ... | 1979 | 231413 |
| isolation and identification of mutants constitutive for aspartokinase iii synthesis in escherichia coli k 12. | we devised a procedure in order to isolate, in escherichia coli, constitutive mutants for aspartokinase iii synthesis, the first enzyme of the lysine regulon. it consists of the introduction of a limiting step in lysine biosynthesis, by the use of the partial suppression of a nonsense mutation. for the first time we could isolate many constitutive mutants. their characteristics (cotransduction with the lysc structural gene; no effect on the synthesis of other enzymes of the regulon; cis-dominanc ... | 1979 | 231461 |
| in vivo transcription and translation of r-plasmid 538-1 dna in escherichia coli. | in vivo transcription and translation of r-plasmid 538-1 in e. coli was analyzed. transcription of individual restriction fragments was determined qualitatively by utilizing the techniques developed by southern (27), and quantitatively by carrying out dna-rna filter hybridization. the most active region of r-plasmid transcription in strains repressed for conjugal transfer was found to occur in the region of the r-plasmid carrying the antibiotic resistance genes. in plasmids derepressed for conju ... | 1979 | 231496 |
| clustered arg genes on a bamhi segment of the escherichia coli chromosome. | bamhi cleavage of dnas from transducing phages gamma darg13 (ppc, argecbh, bfe), gamma darg14 (ppc, argecbh) and gamma darg23 (argecbh) yields three purely gamma dna segments (and, in one case, a fourth), as well as several excherichia coli-dna-containing segments. the length (in kilobases, kb) of the segments, determined by electron microscopy and ararose gel electrophoresis is 4.2, 7.5, 8.4, 6.2, 6.9, and 6.4 kb for gamma darg13; 13.0, 7.5, 4.7, 6.2, 6.9, and 6.4 kb for gamma darg 14: and 5.3, ... | 1979 | 231541 |
| behavior of bacteriophage mu dna upon infecton of escherichia coli cells. | | 1979 | 231663 |
| construction, propagation and expression of simian virus 40 recombinant genomes containing the escherichia coli gene for thymidine kinase and a saccharomyces cerevisae gene for tyrosine transfer rna. | | 1979 | 231664 |
| replication of the colicin e1 plasmid in extracts of escherichia coli: uncoupling of leading strand from lagging strand synthesis. | the replication of the colel plasmid was studied in extracts from e. coli dnag mutants. it was found that the synthesis of the complementary strands of colel dna can be carried out in these extracts in two consecutive steps: (1) synthesis of the leading l strand independent of the dnag function, and (2) synthesis of the lagging h strand depending upon addition of wild-type dnag protein. in contrast to l strand synthesis, the latter reaction is insensitive to rifampicin and novobiocin. both synth ... | 1979 | 231724 |
| dna supercoiling and transcription in escherichia coli: influence of rna polymerase mutations. | coumermycin a1, a specific inhibitor of dna gyrase, differentially changes the spectrum of proteins synthesized in wild type e. coli cells but has no effect on the protein spectrum in mutant cells with coumermycin-resistant dna gyrase. the rpob265 mutation affecting rna polymerase decreases the coumermycin a1-sensitivity of bacteria while the rpoc3 mutation increases it. the interaction of wild type and mutant rpob265 rna polymerases with colel plasmid dna in vitro is differently affected by dna ... | 1979 | 231726 |
| rapid mapping of transposon insertion and deletion mutations in the large ti-plasmids of agrobacterium tumefaciens. | a procedure is presented, that has allowed the rapid assignment of transposon tn1 and tn7 insertion sites in the large (130 md) nopaline ti-plasmid ptic58, to specific restriction enzyme fragments. total bacterial dna is isolated from agrobacterium tumefaciens strain c58 mutants that carry a transposon in their ti-plasmid, and digested with an appropriate restriction endonuclease. the fragments are separated on an agarose gel, denatured and transferred to nitrocellulose filters. these are hybrid ... | 1979 | 231764 |
| in vivo preparation of [32p]camp and thin-layer chromatography of camp-related compounds. | a simple and rapid method for preparing [32p]adenosine 3'5'-cyclic monophosphate (camp) is described. a culture of an escherichia coli mutant which excretes camp about 150 times faster than does a wild-type strain was incubated overnight with [32p]orthophosphate of high specific activity (e.g., 4000 ci/mol (1 ci = 37 gbq). the [32p]camp which accumulated extracellularly was then purified to 99.9% radiochemical purity in less than 4 h by adsorption to charcoal and alumina column chromatography. a ... | 1979 | 231995 |
| selective spin-labeling of the ribosomal proteins of 70s ribosomes from escherichia coli. | we have used a series of n-(1-oxyl-2,2,5,5-tetramethyl-3-pyrrolidinyl) maleimide spin labels of different length to label, covalently and selectively, the most reactive sulfhydryl groups of 70s ribosomal proteins of escherichia coli. under short periods of labeling (1--2 min), less than two spin labels per ribosome are incorporated and were shown to be distributed mainly on five ribosomal proteins in the following order: s18 greater than s21, l27 greater than s17, and s12. with a long period of ... | 1979 | 231998 |
| effect of carbon sources on the rates of cyclic amp synthesis, excretion, and degradation, and the ability to produce beta-galactosidase in escherichia coli. | we have determined the rates of adenosine 3',5'-cyclic monophosphate (camp) synthesis, excretion, and degradation, and the camp pool size in escherichia coli grown on various carbon sources. we have found that the camp pool size increases in approximate proportion to increases in the camp synthetic rate. although the combined rate of excretion and degradation of camp is in approximate proportion to the camp pool size, no such regular relationship is seen between the camp pool size and either the ... | 1979 | 232000 |
| purification & some properties of galactose-1-phosphate uridylyl transferase from e. coli. | | 1979 | 232062 |
| plasmids of escherichia coli as cloning vectors. | | 1979 | 232214 |
| escherichia coli plasmids packageable in vitro in lambda bacteriophage particles. | | 1979 | 232219 |
| a kinetic analysis of cell division, and induction and stability of reca protein in u.v. irradiated ion+ and ion-strains of escherichia coli k12. | kinetic analysis of induction of reca protein synthesis after u.v. irradiation does not show correspondence with the kinetics of division inhibition in ion+ and ion- strains. when the induction of reca protein after u.v. is drastically reduced by rifampicin treatment, no effect on the kinetics of division inhibition is observed. | 1979 | 232229 |
| chromosomal mobilization from a reca mutant of pseudomonas putida. | a methyl methane sulfonate sensitive mutant of p. putida strain ppg1 is also extremely sensitive to uv-rays, compared to parent wild type cells. this mutant behaves typically as recombination less (reca) mutants of escherichia coli and pseudomonas aeruginosa, since as a recipient, it exhibits extremely low frequency of recombination following conjugational, transductional, and transformational gene transfer. sex factor plasmids such as k-xyl or tol can mobilize chromosomal genes equally well bot ... | 1979 | 232230 |
| cloning of the entire region for nitrogen fixation from klebsiella pneumoniae on a multicopy plasmid vehicle in escherichia coli. | | 1979 | 232231 |
| drug-inactivating enzymes of bacteria grown in subminimal inhibitory concentrations of antibiotics. | repeated transfers of strains of escherichia coli and staphylococcus aureus in medium containing subminimal inhibitory concentrations (sub-mics) of gentamicin caused a moderate increase in the minimal inhibitory concentration of gentamicin. at the end of such transfers, e. coli k12 produced aminoglycoside phosphotransferase(3')-i [aph(3')], and e. coli r112, which carries the plasmid-coded enzyme aph(3')-i, also produced the acetylating enzyme aminoglycoside acetyltransferase(2') [aac(2')]. e. c ... | 1979 | 232298 |
| effect of sample transport systems on survival of bacteria in ground beef. | the effects of two transport systems and cryoprotective agents on the survival of bacteria in ground beef samples were evaluated. survival of clostridium perfringens in ground beef samples after simulated transport (72 h) was higher (about 99%) in dry ice than in trans temp shipping units (-3 degrees c). there were no significant differences between the two transport systems in survival of coliforms, escherichia coli, staphylococcus aureus, or aerobic bacteria. mixing ground beef samples at a ra ... | 1979 | 232392 |
| the plasmid system of escherichia coli strain ur12644: identification and molecular characteristics of transposons involved in the generation of endogenous r-plasmids. | | 1979 | 232453 |
| studies on the substrate specificity of the dna methylase activity from escherichia coli k-12. | a partially purified extract of dna methylases from e. coli k-12 containing dna-adenine as well as dna-cytosine methylase activities has been examined with respect to different dna species as substrates. the results show that the natural content of 6-map) in the applied dna represses the dna-adenine methylase activity. on the other hand, 5-mc, already present in the substrate does not influence the activity of the dna-cytosine methylase. dna from micrococcus radiodurans, which is completely free ... | 1979 | 232591 |
| [effect of dna supercoiling on transcription performed by normal and mutant escherichia coli rna-polymerases]. | a specific dna-gyrase, inhibitor, coumermycin a1, causes differential changes in the spectrum of proteins synthesized in e. coli wild types cells, while protein spectrum in the mutant cells with coumermycin-resistant dna-gyrase is left unaffected. the mutation of rna-polymerase rpob265 lowers the sensitivity of bacteria to coumermycin a1, whereas the rpoc3 enhances it. the differences between the normal and mutant rpob265 rna polymerases on interaction in vitro with cole1 dna plasmid depend on i ... | 1979 | 232746 |
| experimental animal models for anaerobic infections. | an experimental animal model that stimulates the mixed aerobic-anaerobic microflora of intraabdominal sepsis was used to study antimicrobial efficacy in vivo. treatment of infected rats with chloramphenicol resulted in only a modest reduction in the percentage of animals surviving infection with abscesses at necropsy. this unanticipated observation led to further exploration of the predominant anaerobes associated with the experimental infection. in vitro cultures of bacteroides fragilis, suscep ... | 1979 | 232936 |
| superoxide, hydrogen peroxide, and oxygen tolerance of oxygen-sensitive mutants of escherichia coli. | oxygen-intolerant mutants of escherichia coli k12 were selected by a replica plating technique after treatment with the mutagen, n-methyl-n'-nitro-n-nitrosoguanidine, to a lethality of 99.5%. one group of mutants had lost the ability to induce both peroxidase and catalase when exposed to oxygen but retained the ability to induce the manganese-superoxide dismutase. the second group of mutants had lost the ability to induce the activity of all these enzymes. failure to induce peroxidase and catala ... | 1979 | 232937 |
| perinatal infections: prevention of long-term sequelae. | all the congenital infections and most of the natal and postnatally acquired infections of man are associated with disease of the central nervous system and long-term sequelae in the survivors. the most important perinatal pathogens in this regard are group b streptococcus, escherichia coli and other coliform bacteria, cytomegalovirus, toxoplasma gondii and herpes simplex virus. all these agents are the subject of active and, in some instances, promising investigation. the strategies for prevent ... | 1979 | 233357 |
| central and peripheral adrenergic mechanisms in endotoxin fever and newborn guinea pigs. | in 0--3 day-old guinea pigs cerebroventricular pretreatment with alpha-methyl-p-tyrosine failed to modify the course of fever induced by e. coli endotoxin administration into the cerebral ventricles. central or intraperitoneal administration of phentolamine or central administration of propranolol were also ineffective. intraperitoneal propranolol, however, prevented both the first and the second temperature rise after endotoxin, while the transient fall in temperature that usually occurs betwee ... | 1979 | 233404 |
| on the role of the reca protein of escherichia coli in general recombination. | | 1979 | 233494 |
| functional stability of the bfe and tonb gene products in escherichia coli. | the expression of several functional properties of the products of the bfe and tonb genes in escherichia coli was measured after the specific termination of the synthesis of the products of these genes. this was accomplished by the use of a temperature-sensitive amber suppressor mutation, which allowed control, by manipulation of the growth temperature, of the level of product formed from suppressible mutant alleles of the bfe or tonb gene. the bfe product is an outer membrane receptor protein f ... | 1977 | 233719 |
| physiological function of superoxide dismutase in glucose-limited chemostat cultures of escherichia coli. | conditions for continuous culture of escherichia coli k-12 his- thi- under glucose limitation were established. both the capacity for respiration, at d greater than 0.2/h, and specific activity of superoxide dismutase increased as a function of specific growth rate, whereas peroxidase and catalase were either invariant with or inversely related to this growth rate. the abrupt increase in the availability of glucose, as a means of elevating the growth rate, was followed by an increase in superoxi ... | 1977 | 233720 |
| changes in protein synthesis on mitomycin c induction of wild-type and mutant clodf13 plasmids. | mitomycin c treatment of escherichia coli k-12 cells containing the nonconjugative plasmid clodf13 resulted in inhibition of host chromosome protein synthesis and a high rate of synthesis of two clodf13-specified proteins whose molecular weights correspond to cloacin and immunity protein. five molecules of immunity protein were synthesized for each cloacin df13 molecule. mitomycin c-treated cells containing a copy mutant of clodf13 made three to four times as much of each protein as cells contai ... | 1977 | 233723 |
| analysis of euglena gracilis chloroplast deoxyribonucleic acid with a restriction endonuclease, ecori. | cleavage of chloroplast deoxyribonucleic acid (dna) of euglena gracilis z with restriction endonuclease ri from escherichia coli (ecori) yielded 23 bands upon electrophoresis in gels of agarose. four of the bands contained twice the stoichiometric amount of dna. one of these bands contained two similarly sized fragments. the sum of the molecular weight of the 24 different fragments equaled the molecular weight of the circular molecule. the restriction fragments had different buoyant densities, w ... | 1977 | 233724 |
| characterization of lambda escherichia coli hybrids carrying chemotaxis genes. | molecular cloning techniques were used to construct hybrid escherichia coli lambda phage and isolate col e1 factors that carried the cheb region of the e. coli genome. the products of these genes were examined by using a series of deletions in the phage to stimulate specific polypeptide synthesis in ultraviolet-irradiated cells and by using col factor to program protein synthesis in minicells. seven flagellar related polypeptides were synthesized. three of these with apparent molecular weights o ... | 1977 | 233725 |
| selected translocation of plasmid genes: frequency and regional specificity of translocation of the tn3 element. | a procedure is described that selects for the insertion of transposable antibiotic resistance elements in a variety of recipient replicons. the selected translocation procedure, which employs a plasmid having a temperature-sensitive defect in replication as a donor of transposable genetic elements, was used to investigate certain characteristics of the translocation process. our results indicate that translocation of the tn3 element from plasmid to plasmid occurs at a 10(3)- to 10(4)-times-highe ... | 1977 | 233726 |
| dominance of dnaa+ to dnaa in escherichia coli. | the dominance of dnaa+ to the dnaa508 mutation was complete and was unaffected by the presence of a copy of the chromosomal replication origin on the episome. these results prove that the dnaa gene of escherichia coli produces a diffusible product. | 1977 | 233727 |
| effect of allogeneic cell interaction and graft-versus-host reaction on the antibody response to escherichia coli 0127 antigen. | | 1975 | 234299 |
| organophosphate-detoxicating enzymes in e. coli. gelfiltration and isoelectric focusing of dfpase, paraoxonase and unspecific phosphohydrolases. | | 1975 | 234391 |
| in vitro activity of sisomicin, an aminoglycoside antibiotic, against clinical isolates. | sisomicin, a new aminoglycoside antibiotic which is produced by micromonospora myoensis, was studied against 565 clinical isolates of gram-negative bacilli and gram-positive cocci. with the exception of serratia marcescens, over 90% of isolates of gram-negative bacilli were inhibited by 1.56 mug/ml or less of sisomicin. sisomicin was slightly more active than gentamicin and tobramycin aganist isolates of escherichia coli, proteus mirabilis and klebsiella spp. it was substantially more active tha ... | 1975 | 234415 |
| adsorption of vibrio parahaemolyticus onto chitin and copepods. | vibrio parahaemolyticus was observed to adsorb onto chitin particles and copepods. the efficiency of adsorption was found to be dependent on ph and on the concentration of nac1 and other ions found in seawater. highest efficiency was observed in water samples collected from chesapeake bay and lowest in water from the open sea. v. parahaemolyticus was found to adborb onto chitin with the highest efficiency of the several bacterial strains tested. escherichia coli and pseudomonas fluorescens d ... | 1975 | 234715 |
| mutants of escherichia coli k12 unable to grow on non-fermentable carbon substrates. | among a number of mutants unable to utilize non-fermentable carbon substrates, scoring for membrane atpase and for atp-driven transhydrogenase activity permitted to distinguish two phenotypes: (a) mutants lacking atpase and atp-driven transhydrogenase; (b) one mutant with an atpase which behaved according to several criteria as released into solution instead of being membrane bound, a.o it exhibited no atp-driven transhydrogenase activity. all a and b mutants exhibited a common nutritional patte ... | 1975 | 234746 |
| assay, characterization, and localization of an enterotoxin produced by salmonella. | an enterotoxic factor isolated from cultures of salmonella yielded reproducible results in the suckling mouse model in contrast to other animal models. the enterotoxin appears to possess properties similar to both the heat-stable and heat-labile enterotoxins of escherichia coli. preliminary results indicate that the toxin is a protein, is located in the cell wall or outer-membrane fraction, and is difficult to separate from other cell wall constituents. | 1975 | 234910 |
| genetic control of glutamine synthetase in klebiella aerogenes. | mutations at two sites, glna and glnb, of the klebsiella aerogenes chromosome result in the loss of glutamine synthetase. the locations of these sites on the chromosome were established by complementation by episomes of escherichia coli and by determination of their linkage to other genetic sites by transduction with phage p1. the glnb gene is located at a position corresponding to 48 min on the taylor map of the e. coli chromosome; it is linked to trya, nadb, and gua. the glna gene is at a posi ... | 1975 | 234939 |
| on the structure-function relationship of acyl carrier protein of escherichia coli. | the conformations of escherichia coli acyl carrier protein (acp) and acetylated acp have been studied as a function of ph and salt concentration by circular dichroism measurements. the results show that the amino groups of acp in their protonated form are important for maintaining the native conformation of the protein at physiological ph. however, externally added cations (divalent more effectively than monovalent ones) can substitute for the ammonium groups in maintaining the ordered structur ... | 1975 | 234965 |
| ketopantoic acid and ketopantoyl lactone reductases. stereospecificity of transfer of hydrogen from reduced nicotinamide adenine dinucleotide phosphate. | the stereospecificity of hydrogen transfer from nadph to the appropriate carbonyl substrate catalyzed by ketopantoic acid and ketopantoyl acid and ketopantoyl lactone reductases of yeast (saccharomyces cerevisiae) and escherichia coli has been determined. yeast and e. coli ketopantoic acid reductases are b-specific enzymes which transfer hydrogen from [4b-3h]-nadph to ketopantoic acid to form [3h]pantoic acid. in contrast to the usual observations on the stereospecificity of functionally similar ... | 1975 | 234966 |
| restoration of coupling factor activity to escherichia coli atpase missing the delta subunit. | | 1975 | 235262 |
| calorimetric analysis of aspartate transcarbamylase from escherichia coli: binding of cytosine 5'-triphosphate and adenosine 5'-triphosphate. | the binding of ctp and atp to aspartate transcarbamylase at ph 7.8 and 8.5 at 25 degrees has been investigated by equilibrium dialysis and flow microcalorimetry. the binding isotherms for ctp at both ph 7.8 and 8.5 and atp at ph 8.5 can be fit by a model which assumes three tight, three moderately tight, and six weak binding sites. the binding isotherms for atp at ph 7.8 are best fit by a model which assumes six tight and six weaker sites. both finite differenceh binding and finite differences b ... | 1975 | 235271 |
| glutamate dehydrogenase from escherichia coli: induction, purification and properties of the enzyme. | when escherichia coli was grown in a minimum medium with glucose as sole carbon source and a proper level of ammonia, nadp+ specific glutamate dehydrogenase (l-glutamate: nadp+ oxidoreductase (deaminating), ed 1.4.1.4) was induced. the enzyme was solubilized by french press treatment and purified to homogeneity by (nh4)2so4 fractionation, heat treatment followed by deae-cellulose, hydroxylapatite and bio-gel chromatography with an overall yield of 30%. the enzyme proved to be heat stable and rel ... | 1975 | 235298 |
| a cyclic adenosine 3',5'-monophosphate-dependent histone kinase from pig brain. purification and some properties of the enzyme. | a cyclic adenosine 3',5'-monophosphate-dependent histone kinase (atp: protein phosphotransferase, ec 2.7.1.37) was isolated from pig brain. the enzyme has been purified 1140-fold; it is homogeneous on polyacrylamide gel electrophoresis and gel filtration. the estimated molecular weight of the enzyme is 120 000. histone kinase dissociates into a catalytic subunit and a regulatory one (molecular weights 40 000 and 90 000, respectively). the catalytic subunit has been obtained in homogeneous state ... | 1975 | 235302 |
| analysis of bacterial biotin-proteins. | the biotin-protein populations in several bacterial strains were analyzed by solubilization of [3h]biotin-labeled cells with sodium dodecylsulfate followed by electrophoresis on polyacrylamide gels containing the detergent. a variety of patterns of biotin-labeled polypeptide chains was seen, ranging from a single biotin-protein in escherichia coli, corresponding to the biotin carboxyl carrier protein component of acetyl-coa carboxylase, to multiple species in enterobacter aerogenes, pseudomonas ... | 1975 | 235315 |
| purine nucleoside phosphorylase from escherichia coli and salmonella typhimurium. purification and some properties. | the purine nucleoside phosphorylases from escherichia coli and from salmonella typhimurium have been purified to electrophoretic homogeneity and crystallized. comparative studies revealed that the two enzymes are very much alike. they obey simple michaelis-menten kinetics for their substrates with the exception of phosphate for which they show negative cooperativity. gel filtration on sephadex g-200 of the native enzymes revealed a molecular weight for both enzymes of 138000 plus or minus 10%. b ... | 1975 | 235429 |
| dibromothymoquinone : an inhibitor of aerobic electron transport at the level of ubiquinone in escherichia coli. | | 1975 | 235466 |
| t lymphocyte function as the principal target of lymphocytic choriomeningitis virus-induced immunosuppression. | plaque-forming cell responses against sheep erythrocytes, escherichia coli lipopolysaccharide, pneumococcal polysaccharide, and polyvinylpyrrolidone were examined in mice infected with lymphocytic choriomeningitis virus. a 92 to 96 percent reduction of the thymus-dependent anti-sheep erythrocyte responses was observed 2 to 4 weeks after infection. however, the thymus-independent responses against the three other antigens were close to normal at all stages of the infetion. studies on allograft ... | 1975 | 235488 |
| xanthosine-5'-phosphate amidotransferase from escherichia coli. | the purified enzyme xanthosine-5'-monophosphate (xmp) aminase from escherichia coli strain b-96 is shown to possess catalytic activity with either glutamine or ammonia as a substrate. this enzyme, which possesses identical subunits, has the following properties: (a) a ph optimum of 8.3 for both aminase and amidotransferase; (b) an apparent k-m for both glutamine and nh3 of 1 mm; (c) an amidotransferase that is approximately 2 times more active than the aminase; (d) a linear relationship between ... | 1975 | 235520 |
| thioredoxin reductase-mediated hydrogen transfer from escherichia coli thioredoxin-(sh)2 to phage t4 thioredoxin-s2. | thioredoxin from escherichia coli b and phage t4-infected e. coli b are small hydrogen carrier proteins which in their reduced forms are specific hydrogen donors to e. coli and t4-induced ribonucleotide reductase, respectively. the oxidation-reduction active group of both thioredoxins consists of a single cystine residue which is reduced to sulfhydryl form by nadph in the presence of e. coli thioredoxin reductase. reduction of t4 thioredoxin-s2 to thioredoxin-(sh)2 led to a 3-fold increase in th ... | 1975 | 235528 |
| enhancement of the glutaminase activity of carbamyl phosphate synthetase by alterations in the interaction between the heavy and light subunits. | glutamine-dependent carbamyl phosphate synthetase (from escherichia coli) was previously shown to be composed of a light subunit (molecular weight similar to 42,000) which has the binding site for glutamine and a heavy subunit (molecular weight similar to 130,000) which has binding sites for the other reactants and allosteric effectors. the subunits may be separated with retention of catalytic activities; only the separated light subunit exhibits glutaminase activity. the previous finding that s ... | 1975 | 235545 |
| use of the sodium borohydride reduction technique to identify a gamma-glutamyl phosphate intermediary in the escherichia coli glutamine synthetase reaction. | incubation of unadenylylated escherichia coli glutamine synthetase with atp, l-[14c]glutamate and metal ion results in the formation of gamma-glutamyl-p which can under appropriate conditions be reduced by sodium borohydride. the acyl-p compound is formed catalytically as judged by the quantity of radioactive alpha-amino-delta-hydroxyvalerate produced compared to the concentration of enzyme subunits. formation of the glutamyl-p compound occurs in the presence of magnesium or manganous ions, and ... | 1975 | 235549 |
| purification and properties of guanosine triphosphate cyclohydrolase ii from escherichia coli. | an enzyme that uses gtp as substrate for the formation in stoichiometric quantities of formate, inorganic pyrophosphate, and 2,5-diamino-6-hydroxy-4-(ribosylamino)pyrimidine-5'-phosphate has been purified 2200-fold from extracts of escherichia coli b. this enzyme is named gtp cyclohydrolase ii to distinguish it from a previously studied e. coli enzyme, named gtp cyclohydrolase (and called gtp cyclohydrolase i in this paper), that catalyzes the first of a series of enzymatic reactions leading to ... | 1975 | 235552 |
| long-chain fatty acyl thioesterases i and ii from escherichia coli. | | 1975 | 235694 |
| biotin carboxyl carrier protein from escherichia coli. | | 1975 | 235698 |
| biotin carboxylase component of acetyl-coa carboxylase from escherichia coli. | | 1975 | 235702 |
| carboxyltransferase component of acetyl-coa carboxylase from escherichia coli. | | 1975 | 235705 |
| heart transplantation in endotoxin shock. | the condition of the heart from dogs in endotoxin shock was evaluated, and all dogs in the control group receiving 5 milligrams per kilogram to eschericia coli endotoxin died within two to 14 hours. hearts from four other dogs receiving the same dosage of endotoxin were allografted orthotopically into healthy recipient dogs. the donor heart was taken in the terminal phase of shock, after the blood pressure of the donor had declined to 50 millimeters of mercury or less. all four heart allografts ... | 1975 | 235795 |
| metal ion requirement by glutamine synthetase of escherichia coli in catalysis of gamma-glutamyl transfer. | | 1975 | 235885 |
| the non-equivalence of the active sites and the mechanism of a mutationally altered e. coli alkaline phosphatase. | | 1975 | 235925 |
| catabolite inactivation of biodegradative threonine dehydratase of escherichia coli. | incubation of escherichia coli cells with glucose, pyruvate, and certain other metabolites led to rapid inactivation of inducible biodegradative threonine dehydratase. analysis with several mutant strains showed that pyruvate, and not a metabolite derived from pyruvate, was capable of inactivating enzyme, and that glucose acted indirectly after being converted to pyruvate. some other alpha-keto acids such as oxaloacetate and alpha-ketobutyrate (but not alpha-ketoglutarate) were also effective. i ... | 1975 | 235965 |
| regulation of escherichia coli glutamine synthetase. evidence for the action of some feedback modifiers at the active site of the unadenylylated enzyme. | the interaction of unadenylylated form of escherichia coli glutamine synthetase with several substrates and effectors has been examined by magnetic resonance techniques. these studies show that two manganese ions bind per enzyme subunit. from the dramatic line broadening observed in the alanine spectra in the presence of manganese and enzyme, it is concluded that the binding of alanine occurs at a site nearer one of the two manganese sites. electron spin resonance (esr) titration experiments sug ... | 1975 | 235974 |
| purification and properties of glutamate binding protein from the periplasmic space of escherichia coli k-12. | glutamate binding protein released from the periplasmic space of escherichia coli k-12 by lysozyme-edta treatment was purified to homogeneity and its physical and chemical properties were studied. it is a basic protein with a pi of 9.1. its molecular weight, determined in an analytical ultracentrifuge, and by gel filtration on sephadex g-100 and dodecylsulphate acrylamide is 29 700, 27 800 and 32 000, respectively. the kd value for glutamate was 6.7 - 10- minus 6 m. l-aspartate, reduced glutathi ... | 1975 | 236016 |