| biological values of the infant, juvenile, and adult agouti (dasyprocta sp) with emphasis on microbial flora. | normal values for intestinal flora were determined on four adult, two juvenile, and four infant agoutis (dasyprocta sp) maintained at our institution. serologic, hematologic, biochemical, and histologic observations were also made on these same agoutis, and serologic, microbiologic, and endoparasitic tests were made on serum and fecal samples from agoutis maintained at other institutions. streptococci, lactobacilli and nonenteropathogenic escherichia coli were isolated from cecal contents of all ... | 1976 | 185456 |
| novel structure at 5'-ends of nascent dna chains. | because of their association with protein short nascent dna chains in escherichia coli can be separated from other cellular dna by chromatography on hydroxylapatite. protein-free dna chains of less than 500 nucleotides in length are resistant to degradation from the 5'-end by alkaline phosphatase [orthophosphoric-monoester phosphohydrolase (alkaline optimum); ec 3.1.3.1] and spleen phosphodiesterase (oligonucleate 3'-nucleotidohydrolase; ec 3.1.4.18). in contrast, dna chains containing more than ... | 1976 | 185611 |
| catabolite modulator factor: a possible mediator of catabolite repression in bacteria. | water soluble extracts of escherichia coli cells have been found to exert an extremely strong repressive effect upon the expression of catabolite sensitive operons. the compound responsible for this activity has been partially purified and proves to be of low molecular weight and heat stable. the effect of this compound, hereafter designated as catabolite modulator factor, is only partially antagonized by adenosine 3':5'-cyclic monophosphate. the possible role of catabolite modulator factor in t ... | 1976 | 185615 |
| ultrastructure of lipopolysaccharides of yersinia enterocolitica, salmonella typhimurium and escherichia coli. | the fine structure of isolated lipopolysaccharides (lps) from the rough and smooth form of an yersinia enterocolitica strain (ye 75 r/ye 75 s) and from smooth forms of salmonella typhimurium (s 1010) and escherichia coli (essen) were examined electron-microscopically by negative staining. partial denaturation of lps in tris-buffer with acid and/or polymyxin b treatment revealed a common structure of strandlike lps. electron-microscopically, lps-strands were found to consist of two identical sub- ... | 1976 | 185850 |
| cyclic adenosine 5'-monophosphate in escherichia coli. | | 1976 | 186018 |
| evidence against the involvement of adenosine 3',5'-cyclic monophosphate in glucose inhibition of beta-galactosidase induction in bacillus megaterium. | when bacillus megaterium cells are grown on d-galactose as the sole carbon source, the cells actively synthesize beta-galactosidase (beta-d-galactoside galactohydrolase, ec 3.2.1.23). however, d-galactose, when added to a glucose-grown culture, did not induce beta-galactosidase, apparently because of the glucose inhibition of the transport of galactose. on the other hand, when glucose was added to a galactose-grown culture, the transport of galactose continued at a reduced but significate rate, ... | 1976 | 186165 |
| regulation of active ion transport in the small intestine. | the epithelium of the small intestine can both actively absorb and actively secrete electrolytes and water. secretion can be elicited in vitro by adding cyclic amp or a stimulator of intestinal mucosal adenylate cyclase (cholera and escherichia coli enterotoxins, prostaglandins, vasoactive intestinal peptide) or an inhibitor of cyclic amp phosphodiesterase (theophylline). cyclic amp appears to alter intestinal ion transport at two different loci: it inhibits a coupled influx process for na+ and ... | 1976 | 186235 |
| the aetiology of diarrhoea in newborn infants. | diarrhoea is a common problem in newborn infants in hospital nurseries. in the past, sporadic diarrhoea was often attributed to dietary indiscretion by the mother, and epidemic diarrhoea was though to be caused by an unknown infectious agent. techniques with which to locate non-cultivable viruses and untypable enteropathogenic strains of escherichia coli allow reevaluation of the aetiology of diarrhoea in newborn infants. preliminary results from melbourne, australia, suggest that most diarrhoea ... | 1976 | 186236 |
| nuclear-magnetic-relaxation studies of the interaction of inhibitor with the threonine-sensitive aspartokinase of escherichia coli. | the nature of the feedback inhibition of the bifunctional enzyme, aspartokinase i-homoserine dehydrogenase i of escherichia coli was studied using 13c nuclear magnetic resonance (nmr). since aspartokinase is activated by mn(ii), the interaction of the inhibitor l-threonine (specifically enriched to 90% 13c in the carboxyl carbon) with the metal-enzyme complex was studied. spin-lattice (t1) and spin-spin (t2) relaxation times were determined by the partially relaxed fourier transform method and l ... | 1976 | 186263 |
| multiple regulation of nucleoside catabolizing enzymes in escherichia coli: effects of 3:5' cyclic amp and crp protein. | the regulation of the synthesis of nucleoside metabolizing enzymes has been studied in cya and crp mutant strains of escherichia coli. the synthesis of the cyt-enzymes, cytidine deaminase and uridine phosphorylase regulated by the cytr gene product, is activated by the camp-crp complex. on the other hand the synthesis of the deoenzymes: deoxyriboaldolase, thymidine phosphorylase, phosphodeoxyribomutase and purine nucleoside phosphorylase, appears to be increased if an active camp-crp complex can ... | 1976 | 186698 |
| dna gyrase: an enzyme that introduces superhelical turns into dna. | relaxed closed-circular dna is converted to negatively supercoiled dna by dna gyrase. this enzyme has been purified from escherichia coli cells. the reaction requires atp and mg++ and is stimulated by spermidine. the enzyme acts equally well on relaxed closed-circular colicin e1, phage lambda, and simian virus 40 dna. the final superhelix density of the dna can be considerably greater than that found in intracellularly supercoiled dna. | 1976 | 186775 |
| [formation of escherichia coli resistance to amidine penicillin]. | | 1976 | 187015 |
| phosphorylation of cardiac regulatory proteins by cyclic amp-dependent protein kinase. | cardiac myofibrils were purified from canine myocardium, and the regulatory proteins (troponin + tropomyosin) were extracted and shown to contain endogenous cyclic amp-dependent protein kinase activity. other cyclic nucleotide stimulated the protein kinase activity but only at higher concentrations. the enzyme was able to catalyze phosphorylation of conventional substrates such as histones and casein as well as a component of the regulatory protein fraction with a molecular weight of 28,000 dalt ... | 1976 | 187066 |
| [carboyydrates localization on ultrathin sections of "brucella" and "escherichia" cells in smooth (s) and rough (r) phase (author's transl)]. | carbohydrates localization on ultrathin sections of brucella abortus, melitensis and excherichia coli cells has been studied by the periodic acid thiocarbohydrazide-silver proteinate (patag) and phosphotungstic acid (pta) methods. carbohydrates are mainly localized on the cell envelope of brucella and escherichia but there are several differences between these two bacteria. the differences are discussed and a brucella polysaccharide envelope model is proposed. the patag method gives the same sil ... | 1976 | 187096 |
| immunotherapy with nonviable microbial components. | structural components of microorganisms have been studied for immunopotentiating effect with the aid of transplantable (line 10) tumors in syngeneic guinea pigs. microbial components were associated with oil droplets, suspended in tween-saline, and injected intralesionally. bcg cell walls, given in this way, produced regression and cure of 50-60% of established tumors, as did viable bcg. lipid extraction markedly reduced the tumor-regressing potency of cell walls, but p3, a trehalose mycolate pr ... | 1976 | 187099 |
| ribosomal-associated phosphatidylserine synthetase from escherichia coli: purification by substrate-specific elution from phosphocellulose using cytidine 5'-diphospho-1,2-diacyl-sn-glycerol. | cytidine 5'-diphospho-1,2-diacyl-sn-glycerol (cdpdiglyceride):l-serine o-phosphatidyltransferase (ec 2.7.8.8, phosphatidylserine synthetase) is bound tightly to the ribosomes in crude extracts of escherichia coli. after separation of the enzyme from the ribosomes by the method of raetz and kennedy (raetz, c.r.h., and kennedy, e.p. (1974), j. biol. chem. 249, 5038), we have purified the enzyme to 97% of homogenekty. the major portion of the overall 5500-fold purification was attained by substrate ... | 1976 | 187212 |
| a study of the enzymic dephosphorylation of beta-casein and a derived phosphopeptide. | beta-casein, and the phosphate containing peptide derived from it by tryptic digestion, have been dephosphorylated by the action of two phosphatases. escherichia coli alkaline phosphatase (ec 3.1.3.1) has been shown to remove the phosphates from these substrates in two distinct stages. substrate molecules retaining three of the original phosphoseryl residues accumulate during the reaction and are resistant to further dephosphorylation at low enzyme concentrations. in contrast bovine spleen phosp ... | 1976 | 187232 |
| selenalysine and protein synthesis. | selenalysine is a lysine analog having the gamma-methylene group substituted by a selenium atom. it has been demonstrated that selenalysine is activated and transferred to trnalys by either escherichia coli or rat liver aminoacyl-trna synthetases, and inhibits lysine incorporation into polypeptides in protein-synthesizing systems from e. coli, rat liver or rabbit reticulocytes. all tests were performed in comparison with thialysine, a lysine analog having the gamma-methylene group substituted by ... | 1976 | 187234 |
| [effect of detergents and proteolytic enzymes on membrane-bound phosphohydrolases in escherichia coli cells with repressed and depressed biosynthesis of these enzymes]. | solubilization of protein membranes by detergents and protein liberation from the membranes induced by proteolytic enzymes results in a change of activity of membrane-bound phosphohydrolases--alkaline phosphatase and polyphosphatase. the activity of enzymes under conditions of repressed and derepressed biosynthesis of phosphohydrolases changes differently, thus indicating their different membrane environment in the two types of membranes. some data were obtained on the localization of alkaline p ... | 1976 | 187255 |
| composition, associated tissue methyltransferase activity, and catabolic end products of transfer rna from carcinogen-induced hepatoma and normal monkey livers. | this investigation was designed to explore transfer rna (trna) methyltransferase activity, urinary excretion levels of trna degradation products, and trna base composition in normal monkeys and in those with hepatocellular carcinomas induced by n-nitrosodiethylamine. after the development of the tumor, 24-hr urine specimens were collected, the monkeys were sacrificed, and the livers were removed for trna isolation and methyltransferase activity studies. the trna methyltransferase activity and ca ... | 1977 | 187335 |
| electron transport in mutants of escherichia coli deficient in their ability to synthesize adenosine 3':5'-cyclic monophosphate and the catabolite-gene activator protein. | | 1976 | 187492 |
| [effect of 2,6-diaminopurine resistance mutations on adenine and adenosine assimilation by cells of an adenine-dependent strain of escherichia coli k-12]. | in purine-requiring strain of escherichia coli k-12 defective in purine nucleoside phosphorylase (pur, pup) mutants (designated apt) have been obtained that are resistant to 2,6-diaminopurine on guanine-containing medium and incapable to utilize adenine for their growth at 42degreesc, but they are still sensitive to the analogue and can utilize adenine at 28degreesc. it has been shown that the introduction of the corresponding apt mutations in the genome of adenine-requiring strains impaired the ... | 1976 | 187528 |
| cyclic adenosine 3',5'-monophosphate levels and activities of adenylate cyclase and cyclic adenosine 3',5'-monophosphate phosphodiesterase in pseudomonas and bacteroides. | a modified gilman assay was used to determine the concentrations of cyclic adenosine 3',5'-monophosphate (camp) in rapidly filtered cells and in the culture filtrates of pseudomonas aeruginosa, escherichia coli k-12, and bacteroides fragilis. in p. aeruginosa cultures, levels of camp in the filtrate increased with the culture absorbance (3.5 to 19.8 x 10(-9) m) but did not vary significantly with the carbon source used to support growth. intracellular concentrations (0.8 to 3.2 x 10(-5) m) were ... | 1977 | 187575 |
| transcription of polyoma virus dna in vitro. localization of escherichia coli rna polymerase initiation sites. | | 1976 | 187757 |
| [celiac-disease-like malabsorption in escherichia coli o 124 enteritis]. | | 1976 | 187825 |
| excision in vitro of the dna bound carcinogen, 4-nitroquinoline 1-oxide. | it has been shown that 4-hydroxyaminoquinoline 1-oxide, the proximate form of the carcinogen 4-nitroquinoline 1-oxide, binds covalently to the purine bases of dna. here we report that carcinogen-bound nucleotides can be excised from dna by a 5' leads to 3' exonuclease associated with dna polymerase i of e. coli in the forms of either mononucleotides or oligonucleotides. beef spleen phosphodiesterase ii (5' leads to 3') also split carcinogen-bound nucleotides, while a 3' leads to 5' exonuclease o ... | 1976 | 188019 |
| cyclic nucleotides in bacteria. | the question of the ubiquity of cyclic amp in bacteria is not yet closed. the recent introduction of more sensitive and reliable assays for cyclic amp should settle the problem. my prediction is that although there may be some organisms that do not contain cyclic amp, they probably have some yet undiscovered regulatory nucleotides that play similar roles. although cyclic amp has been shown to be unessential for growth of e. coli under optimal laboratory conditions in glucose-containing medium, i ... | 1976 | 188312 |
| disruption of escherichia coli outer membranes by em 49. a new membrane active peptide. | a new peptide antibiotic, em 49, is shown to disrupt the structure of escherichia coli outer membranes and release outer membrane fragments into the surrounding media. evidence supporting this conclusion indludes em 49 stimulated release of outer membrane phospholipids, lipopolysaccharide, and membrane fragments having a phospholipid and polypeptide composition similar to outer membranes. the density of the membrane fragments released by em 49 was 1.22 g/cm3, which was identical to isolated oute ... | 1976 | 188442 |
| [isolation, purification and substrate specificity of aminoglycoside phosphotransferase from escherichia coli 182]. | | 1976 | 188610 |
| [spin label study of conformational changes in escherichia coli rna polymerase at different stages of rna synthesis on t2 dna]. | | 1976 | 188611 |
| glucose effect in tgl mutant of escherichia col k12 defective in methyl-alpha-d-glucoside transport. | 1. the dependence of the rate of accumulation of methyl-alpha-d-glucoside on its extracellular concentration was studied in the tgl mutant of escherichia coli k12, isolated earlier. it has been shown that the kinetics of methyl-alpha-d-glucoside transport differ sharply from those in wild-type bacteria. 2. the beta-galactosidase synthesis in tgl strain is much less sensitive both to permanent and transient glucose catabolite repression. the level of cyclic amp in mutant cells under the condition ... | 1977 | 188655 |
| nature of the free radical in ribonucleotide reductase from escherichia coli. | ribonucleotide reductase from escherichia coli consists of two nonidentical subunits, proteins b1 and b2. the active site of the enzyme is made up from both subunits. protein b2 contributes inter alia an organic free radical which gives a characteristic epr signal. this radical was now located by isotope substitution experiments to the beta position of a tyrosine residue. the epr spectrum of protein b2 from bacteria grown in a completely deuterated medium was drastically changed. the change was ... | 1977 | 188819 |
| aminoacylation of encephalomyocarditis virus rna. | rna extracted from purified encephalomyocarditis (emc) virus (emc-rna) can be aminoacylated with synthetase praparations from escherichia coli, beef and rabbit liver. the extent of aminoacylation is between 0-024 and 0-080 moles per mole emc-rna and occurs only with serine. either removal of possible low mol. wt. contaminants with 3 m-sodium acetate nor periodate oxidation of the virus rna affects its aminoacylation capacity. | 1977 | 188978 |
| protection of mice against encephalomyocarditis virus infection by preparations of transfer rna. | preparations of bacterial transfer rna (trna), give dose-dependent protection of mice against encephalomyocarditis (emc) virus infection at up to i mg trna per mouse with maximum response when the trna is administered around 6 h before infection. protection occurs with intraperitoneally and intravenously administered trna against infections by both these routes. in some experiments significant protection occurs by single treatments of trna up to 24 h after infection with virus doses of i x ld100 ... | 1977 | 188982 |
| synthesis of the tumour antigen and the major capsid protein of simian virus 40 in a cell-free system derived from escherichia coli. | | 1976 | 189036 |
| evidence for a diffusible t4 bacteriophage protein governing the initiation of delayed early rna synthesis. | two forms of prereplicative phage rna can be discerned in escherichia coli early after infection with bacteriophage t4, immediate early and delayed early rna. the transition from immediate early to delayed early rna synthesis is inhibited by chloramphenicol. the present work presents evidence for the existence of a phage-specific protein, which effects this transition. delayed early rna formation was measured by a cistron-specific enzyme-forming-capacity method, in which rna synthesized in the p ... | 1977 | 189081 |
| synthesis of cytochrome c oxidase polypeptides in an escherichia coli cell-free system directed by saccharomyces cerevisiae mitochondrial dna. | using purified yeast mitochondrial dna as a template for e. coli rna polymerase (holoenzyme) complementary mitochondrial rna has been synthesized in vitro. this rna has been used to direct a low background e. coli s-30 protein-synthesizing system. the synthesis of mitochondrial polypeptides has been detected by using antiserum raised against purified cytochrome c oxidase holoenzyme and shown to be specific for this antigen. the antiserum-antigen complex was dissociated and subject to sds-polyacr ... | 1977 | 189180 |
| nucleotide sequence of the 5' end of arabad operon messenger rna in escherichia coli b/r. | the transcription reaction in vitro provides a means of analyzing the nucleotide sequence of the mrna of the arabad operon. by controlling the time of synthesis, we obtained arabad mrna of varying lengths beginning from the 5' end. these 5' fragments were freed of lambda rna transcripts by successive hybridizations to the sense strands of a pair of lambda ara transducing phages that carry ara genes in opposite orientations. the purified 5' fragments were ordered by their times of appearance duri ... | 1977 | 189315 |
| comparison of the binding properties of two 6 beta-amidinopenicillanic acid derivatives that differ in their physiological effects on escherichia coli. | the 6-beta-amidinopenicillanic acid derivative, mecillinam, was highly specific in its action on the growth of escherichia coli. concentrations from the minimal inhibitory concentration (0.05 mug/ml) up to at least 200 mug/ml resulted in the conversion of e. coli rods into osmotically stable spherical cells without significantly inhibiting cell growth or causing cell lysis. a second amidinopenicillanic acid derivative [6-([4-morpholinylmethylene] amino) penicillanic acid] showed identical effect ... | 1977 | 189683 |
| properties of xanthosine 5'-monophosphate-amidotransferase from escherichia coli. | | 1977 | 189701 |
| the site for catabolite deactivation in the l-arabinose bad operon in escherichia coli b/r. | a series of deletions beginning in the leu operon and continuing into the arac gene and also into the ara controlling site region were analyzed in reciprocal merodiploids, e.g., f' a2cc67/b24delta719, f' b24delta719/a2cc67, for their effects on catabolite deactivation (cd). the results of these experiments are consistent with placing the catabolite gene activator-cyclic amp sensitive site in the controlling site region between arab and arao. with a deletion mutant, delta1109, that places arabad ... | 1976 | 189718 |
| pyrimidine ribonucleoside monophosphokinase and the mode of rna turnover in bacillus subtilis. | a protein catalyzing the phosphorylation of cmp to cdp was purified and characterized. kinase activity for ump copurified during ammonium sulfate fractionation, deae-cellulose and hydroxylapatite chromatography, and gel filtration on sephadex g-75, the ratios of activities for the two substrates remaining constant. the purified product, possessing both activities was homogeneous as judged by the single band following polyacrylamide gel electrophoresis. the protein showed no kinase activity again ... | 1976 | 189719 |
| changes in intestinal structure and function of neonatal calves infected with reovirus-like agent and eschericia coli. | measurements of villus/crypt length ratio and mucosal beta-galactosidase activity were made on calves less than 3 weeks of age which had diarrhoea associated with reovirus-like agent and e. coli. in calves with diarrhoea, the villus/crypt length ratios at all sites examined along the small intestine were less than in normal calves of similar age. this was attributed to a reduction in length of vili in calves infected with the reovirus-like agent. the activity of mucosal beta-galactosidase in the ... | 1976 | 189746 |
| magnetic resonance and kinetic studies of the role of the divalent cation activator of rna polymerase from escherichia coli. | the interaction of mn2+, substrates and initiators with rna polymerase have been studied by kinetic and magnetic resonance methods. as determined by electron paramagnetic resonance, mn2+ binds to rna polymerase at one tight binding site with a dissociation constant less than 10 mum and at 6 +/- 1 weak binding sites with dissociation constants 100-fold greater. the binding of mn2+ to rna polymerase at both types of sites causes an order of magnitude enhancement of the paramagnetic effect of mn2+ ... | 1977 | 189795 |
| fluorescence and nucleotide binding properties of escherichia coli uridine diphosphate galactose 4-epimerase: support for a model for nonstereospedific action. | the fluorescence emission spectrum for reduced diphosphopyridine nucleotide (dpnh) in escherichia coli uridine diphosphate galactose 4-epimerase-dpnh complexes has a maximum at 435 nm, which is about twice as intense when the excitation is at 280 nm as at 340 nm. the fluorescence excitation spectrum monitored at 460 nm has two maxima, one at 340-345 nm and another about twice as intense at 280 nm. the polarization of dpnh fluorescence by these complexes is 0.43-0.44 compared with 0.46 for dpnh i ... | 1977 | 189796 |
| characterization of dna strand breakage in vitro by the antitumor protein neocarzinostatin. | the antitumor protein antibiotic neocarzinostatin causes strand scission of dna in vitro in the presence of a sulfhydryl compound. the breaks are single stranded in nature and bear 5'-phosphoryl termini. all four deoxymononucleotides are recoverable at the 5'-ends of the cleavage sites although a higher proportion of dgmp and tmp are consistently found. the lesions are not repairable with polynucleotide ligase from escherichia coli. a quantitative assay was developed to determine the ph profile ... | 1977 | 189801 |
| evidence that the catalytic and regulatory functions of carbamylphosphate synthetase from escherichia coli are not dependent on oligomer formation. | carbamyl-phosphate synthetase from escherichia coli is an allosteric enzyme which undergoes reversible association reactions in phosphate buffer. the positive allosteric effectors, ornithine, inosine 5'-monophosphate (imp), and ammonia, facilitate oligomer formation, whereas uridine 5'-monophosphate (ump), a negative effector, prevents or decreases oligomer formation. when the enzyme is immobilized by reaction with activated sepharose, under conditions where the enzyme exists only as a monomer, ... | 1977 | 189805 |
| binding of allosteric effectors to carbamyl-phosphate synthetase from escherichia coli. | the binding of ornithine and inosine 5'-monophosphate (imp), positive allosteric effectors, and of uridine 5'-monophosphate (ump), a negative allosteric effector, to carbamyl-phosphate synthetase from escherichia coli was studied by the technique of equilibrium dialysis. the monomeric form of the enzyme has one binding site for each of the three allosteric ligands. the binding of ump is inhibited by ornithine, imp, mgatp, and ammonia (also a positive allosteric effector). bicarbonate, l-glutamin ... | 1977 | 189806 |
| glucocorticoid receptor-steroid complex binding to dna. competition between dna and dna-cellulose. | the binding of the glucocorticoid receptor-steroid complex from a line of rat hepatoma tissue culture (htc) cells to dna has been examined. an equilibrium competition assay involving a constant, low total amount of double-stranded dna was developed to compare the complex binding ability of dna free in solution and bound to cellulose. this binding ability is lowered by a factor of five when dna is associated with cellulose. similar studies with htc cell, calf-thymus, and escherichia coli dna reve ... | 1977 | 189840 |
| hydrolysis of steroid glucuronides with beta-glucuronidase preparations from bovine liver, helix pomatia, and e. coli. | we determined the enzymic activity of beta-glucuronidase preparations from bovine liver, helix pomatia, and escherischia coli with steroid glucuronides and nonsteroid glucuronides as substrates. we also studied the effect of na2so4 on the enzymic hydrolysis of several substrates with the three preparations of beta-glucuronidase. na2so4 increases the rate of hydrolysis of all substrates with beta-glucuronidase from bovine liver. hydrolysis of a steroid glucoronide with beta-glucuronidase from hel ... | 1977 | 189953 |
| purification and properties of a periplasmic protein related to sn-glycerol-3-phosphate transport in escherichia coli. | protein glpt, a periplasmic protein previously recognized as closely related to the active transport of sn-glycerol-3-phosphate in escherichia coli was isolated by the cold osmotic shock procedure. it was purified by sephadex chromatography and isoelectric focussing. the purified protein does not exhibit any detectable binding activity toward sn-glycerol-3-phosphate. it has no activity as a glycerol phosphatase nor as a glycerol kinase. polyacrylamide gel electrophoresis in the presence of dodec ... | 1977 | 190005 |
| polyoma genome transcription in transformed mouse cells growing in culture and as tumors in syngeneic mice. | the strands of the polyoma genome coding for early and late viral rna were separated by means of asymmetric crna synthesized under high salt conditions by escherichia coli rna polymerase. each strand was then employed in rna-dna hybridization experiments to determine the degree to which it is transcribed in transformed cells under several conditions. except for a concanavalin-a-selected revertant, approximately one-quarter of the early strand was expressed in all of the situations investigated. ... | 1977 | 190175 |
| reduction of iron and synthesis of protoheme by spirillum itersonii and other organisms. | membranes from spirillum itersonii reduce ferric iron to ferrous iron with reduced nicotinamide adenine dinucleotide or succinate as a source of reductant. iron reduction was measured spectrophotometrically at 562 nm using ferrozine, which chelates ferrous iron specifically. reduced nicotinamide adenine dinucleotide or succinate was also effective as a source of iron. the effects of respiratory inhibitors suggested that reduction of iron occurs at one or more sites on the respiratory chain befor ... | 1977 | 190208 |
| constitutive mutations in the controlling site region of the arabad operon of escherichia coli b/r that decrease sensitivity to catabolite repression. | strains of escherichia coli b/r containing a deletion of the regulatory gene arac are ara-. slow-growing revertants of these strains were isolated and designated aralc because they contain a second mutation in a controlling site, aral, that allows for a low level of constitutive expression of the arabad operon (englesbert et al., 1969). we mutagenized aralc delta c strains and selected mutants that grow faster in mineral l-arabinose medium. the new mutations, called araxc, map very close to the ... | 1977 | 190211 |
| functional mosaicism of membrane proteins in vesicles of escherichia coli. | membrane vesicles of escherichia coli prepared by osmotic lysis of lysozyme ethylenediaminetetracetate (edta) spheroplasts have approximately 60% of the total membrane-bound reduced nicotinamide adenine dinucleotide (nadh) dehydrogenase (ed 1.6.99.3) and mg2+-adenosine triphosphatase (atpase) (ec 3.6.1.3) activities exposed on the outer surface of the inner membrane. absorption of these vesicles with antiserum prepared against the purified soluble mg2+-atpase resulted in agglutination of approxi ... | 1977 | 190212 |
| variation in enterotoxigenicity of escherichia coli. | the possibility that the variable severity of diarrheal disease due to enterotoxigenic escherichia coli might be explained by quantitative differences in the activity of heat-labile enterotoxin was examined. the amount of toxin secreted by 13 enteropathogenic strains of e. coli was quantitated by measurements of the toxin-dependent increase in adenosine 3':5'-cyclic phosphate (cyclic amp) in chinese hamster ovary cells. the activity ranged from 150 pmol of cyclic amp/ml per mg of protein to 4,04 ... | 1977 | 190329 |
| a gal region mutant that requires camp for growth on galactose in an adenyl cyclase negative (cya delta) background. | strains of escherichia coli k12 that contain a deletion of the adenyl cyclase gen (cya delta), required for the synthesis of cyclic adenosine-3';5' monophosphate (camp), grow on galactose-containing minimal medium. a mutant was isolated that grows on this medium only if camp is added. the mutation (designated galp20) is linked to the gal operon region as determined by both generalized transduction with bacteriophage p1 and specialized transduction with bacteriophage lambda. studies with galp20 c ... | 1977 | 190530 |
| effect of formaldehyde on disinfection of filtered air under positive pressure (fapp) type house. | effect of formaldehyde liberated from formalin on disinfection of the surface of a filtered air under positive pressure (fapp) house and the surface of equipment placed in the house was studied. escherichia coli, staphylococcus aureus and avian adenovirus were used in this study as a indicator to evaluate degree of disinfection. satisfactory degree of disinfection of the house and equipment was obtained when formaldehyde was liberated from 40 ml. of formalin per 1 m.3 capacity. bacteria and viru ... | 1976 | 190599 |
| [microbial resistance to formaldehyde. i. comparative quantitative studies in some selected species of vegetative bacteria, bacterial spores, fungi, bacteriophages and viruses]. | the resistence of different microorganisms to formaldehyde was determined. as test objects served gram-negative and gram-positive vegetative germs (klebsiella pneumoniae, pseudomonas aeruginosa, salmonella paratyphi-b, staphylococcus aureus, streptococcus faecalis), bacterial spores (bacillus cereus, bacillus pumilus, bacillus stearothermophilus, bacillus subtilis), fungi (aspergillus niger, candida albicans), bacteriophages (escherichia coli phages, t1, t2, t3), and viruses (adenovirus, poliomy ... | 1976 | 190825 |
| in vitro stimulation of human lymphocytes by bordetella pertussis. | bordetella pertussis (b.p.) induces blast transformation of human lymphocytes; whole killed b.p. are more efficient than extracts obtained by sonication. similar responses were obtained with each of the four strains used in the danish pertussis vaccine. b.p. with low amounts of protective antigen and histamine-sensitizing factor also induced lymphocyte transformation, but were less toxic to the lymphocytes at high concentrations. the supernatants of b.p. cultures were purified with respect to ly ... | 1977 | 190855 |
| the effect of antibiotics on the electrical polarisability of aqueous suspensions of bacteria. | the orientation of washed escherichia coli bacteria in suspension induced by applied a.c. electric fields has been monitored by observing the accompanying changes in the intensity of light scattered by the suspension. the data enable the anisotropy of electrical polarisability deltaalpha to be determined. changes in deltaalpha due to the addition of various antibiotics to the suspension have been measured as a function of both the antibiotic concentration and the temperature of the suspension. t ... | 1977 | 191089 |
| [a mechanism of mononucleotide formation under endonuclease hydrolysis]. | it has been shown under poly-a hydrolysis by endonuclease a236 in the presence of large amounts of e. coli phosphatase that the formation of mononucleotides requires the presence of terminal 5'-p in the substrate. simultaneously, it has been found for endonuclease a236 and nuclease of serratia marcescens that the products of exhaustive hydrolysis carried out in the presence of excess amounts of phosphatase contain an additional nucleoside residue as compared to the ordinary products of exhaustiv ... | 1976 | 191103 |
| nucleotide sequence of a region in 23-s rna adjacent to peptidyl transferase catalytic center of escherichia coli ribosomes. | n-iodoacetylphenylalanyl-trnaphe was used as an affinity label to localize the rna components intimately involved in the catalytic center of escherichia coli ribosomes. this analogue could alkylate the specific region of 23-s rna that waslocated within 2000 nucleotides from the 3' terminus of the molecule. sequence analysis revealed that the alkylation by the active substrate (n-iodoacetylphenylalanyl-trnaphe) was directed to 5'-terminal adenosine residue of a heptanucleotide, a-u-u-u-u-a-gp, wh ... | 1977 | 191254 |
| arabinose nucleoside triphosphates are no inhibitors for dna-dependent rna polymerases. | 1-beta-d-arabinofuranosylcytosine-5' -triphosphate and 9-beta-d-arabinofuranosyladenosine-5' -triphosphate were found to have no inhibitory potency for both mammalian dna-dependent rna polymerase ii and e. coli dna-dependent rna polymerase. | 1976 | 191280 |
| effect of variations in lipopolysaccharide on the fluidity of the outer membrane of escherichia coli. | the lipid hydrocarbon chains in the outer membrane of gram-negative bacteria appear from previous experiments to be less mobile than in the cytoplasmic membrane. to determine whether lipopolysaccharide, a unique outer membrane component, is a cause of this restricted mobility, outer membranes differing in the amount of lipopolysaccharide, and the length of the polysaccharide side chain, were prepared from escherichia coli j5. cytoplasmic membranes were prepared for comparison. the probes, 5- and ... | 1977 | 191452 |
| initiation of synthesis of messenger rna of deoxynucleotide kinase by oligoribonucleotides. | the effects of nucleoside triphosphates and oligoribonucleotides on the initiation of synthesis of messenger rna of the t4 phage-specific enzyme, deoxynucleotide kinase, have been studied. the procedure involved incubation of t4 dna, purified rna polymerase from escherichia coli, and selected nucleotide compounds during a brief period to permit initiation of rna synthesis. further initiation was arrested by the addition of ribampicin, and completion of the transcription of the newly initiated rn ... | 1977 | 191458 |
| production of 6-aminopenicillanic acid with immobilized escherichia coli acylase. | | 1976 | 191731 |
| a phospholipid derivative of cytosine arabinoside and its conversion to phosphatidylinositol by animal tissue. | we have synthesized an analog (ara-cdp-dl-dipalmitin) of cytidine diphosphate diglyceride (cdp-diglyceride) in which the antitumor drug, cytosine arabinoside, is substituted for the cytidine moiety. enzymes in rat and human liver convert this analog to phosphatidylinositol, thereby releasing cytosine arabinoside-5'-monophosphate, an obligatory intermediate in the activation of cytosine arabinoside. unlike cytidine diphosphate diglyceride, however, ara-cdp-dl-diapalmitin is not an efficient subst ... | 1977 | 191910 |
| in vitro lymphocyte transformation of ms patients to paramyxovirus antigens. | the immune response of 21 ms patients and 21 healthy volunteers was tested in vitro lymphocyte transformation assay. the stimulating antigens were measles, mumps, parainfluenza, e. coli, s. aureus and c. albicans. ms patients were found to respond similarly to the normal controls to all antigens tested with the exception of mumps antigen. the maximum responses of the ms patients to this antigen were significantly lower than those observed for the normals. however, since 95 per cent of the ms low ... | 1977 | 192034 |
| interaction of substrates and inhibitors with the homoserine dehydrogenase of kinase-inactivated aspartokinase i. | the aspartokinase activity of the aspartokinase-homoserine dehydrogenase complex of escherichia coli was affinity labeled with substrates atp, aspartate, and feedback inhibitor threonine. exchange-inert ternary adducts of co(iii)-aspartokinase and either atp, aspartate or threonine were formed by oxidation of corresponding co(ii) ternary complexes with h2o2. the ternary enzyme-co(iii)-threonine adduct (i) had 3.8 threonine binding sites per tetramer, one-half that of the native enzyme. the bindi ... | 1977 | 192265 |
| fluorescence energy transfer between heterologous active sites of affinity-labeled aspartokinase of escherichia coli. | the distance between aspartokinase and homoserine dehydrogenase active sites was determined using fluorescence energy transfer between modified substrates. the fluorescent 1,n(6)-ethenoadenosine 5'-triphosphate was bound at the kinase active site by co(iii) affinity labeling. reduced thionicotinamide adenine dinucleotide phosphate quenched the fluorescence of bound nucleotide. fluorescence depolarization measurements led to a delimitation of the value of the dipolar orientation factor to the ran ... | 1977 | 192266 |
| a confirmation of the phase behavior of escherichia coli cytoplasmic membrane lipids by x-ray diffraction. | the lipid fatty acid composition of the cytoplasmic membranes of escherichia coli can be varied by growing an unsaturated fatty acid auxotroph in the presence of different fatty acid supplements. electron spin resonance (esr) studies of spin-label partitioning into the cytoplasmic membranes of different lipid fatty acid compositions as a function of temperature have been interpreted as indicating a broad order-to-disorder transition in the membrane lipids, the end points of the transition depend ... | 1977 | 192270 |
| inhibition of escherichia coli growth and respiration by polymyxin b covalently attached to agarose beads. | polymyxin b was attached to agarose beads by stable covalent bonds and the antimicrobial activity of the immobilized peptide was examined. polymyxin-agarose inhibited the growth of escherichia coli and pseudomonas aeruginosa, but not bacillus subtilis. in addition, the respiration of e. coli, e. coli spheroplasts, and b. subtilis protoplasts was inhibited by immobilized polymyxin, whereas the respiration of b. subtilis was unaffected by polymyxin-agarose. the activity of polymyxin-agarose was no ... | 1977 | 192271 |
| fluorescent derivatives of the pyruvate dehydrogenase component of the escherichia coli pyruvate dehydrogenase complex. | one sulfhydryl group per polypeptide chain of the pyruvate dehydrogenase component of the pyruvate dehydrogenase multienzyme complex from escherichia coli was selectively labeled with n-[p-(2-benzoxazoyl)phenyl]-maleimide (nbm), 4-dimethylamino-4-magnitude of-maleimidostilbene (nsm), and n-(4-dimethylamino-3,5-dinitrophenyl)maleimide (ddpm) in 0.05 m potassium phosphate (ph 7). modification of the sulfhydryl group did not alter the enzymatic activity or the binding of 8-anilino-1-naphthalenesulf ... | 1977 | 192277 |
| [the formation of atp from adenosine 5'-phosphoroimidazolide and pyrophosphate catalyzed by valyl-trna-synthetase]. | the formation of 32p-atp from adenosine 5'-phosphoroimidazolide and 32p-pyrophosphate brought about valine: trna-ligase of e. coli is demonstrated in the standard conditions of pyrophosphate exchange for aminoacyl-trna synthetases. the role the enzyme as specific matrix is suggested. | 1976 | 192333 |
| role of divalent ions in folding of trna. | the native structure of trna is not achieved in low salt (4.5 mm na+, 25 degrees c), but can be restored by addition of divalent ions. we have explored the structure of the central region in escherichia coli trnafmet by absorption and emission spectroscopy of 4-thiouracil, and the structure of the anticodon loop in yeast trnaphe by fluorescence of the 'y' base, versus the number of manganese ions bound to trna, which was derived from electron spin resonance. the fluorescence of the reduced 8-13 ... | 1977 | 192553 |
| regulation of two phosphatases and a cyclic phosphodiesterase of salmonella typhimurium. | the regulation of three salmonella typhimurium phosphatases in reponse to different nutritional limitations has been studied. two enzymes, an acid hexose phosphatase (ec 3.1.3.2) and a cyclic phosphodiesterase (ec 3.1.4.d), appear to be regulated by the cyclic adenosine 3' ,5'-monophosphate (amp) catabolite repression system. levels of these enzymes increased in cells grown on poor carbon sources but not in cells grown on poor nitrogen or phosphorus sources. mutants lacking adenyl cyclase did no ... | 1977 | 192713 |
| biochemical characterization of an escherichia coli hist strain. | an escherichia coli hist strain was characterized biochemically and shown to contain altered transfer ribonucleic acid and to be altered in the regulation of amino acid biosynthesis. | 1977 | 192717 |
| differential binding of cyclic adenosine 3' ,5'-monophosphate to the cyclic adenosine 3' ,5'-monophosphate receptor protein in escherichia coli. | binding of cyclic adenosine 3' ,5'-monophosphate (camp) by the camp receptor protein in crude cell-free extracts of escherichia coli was characterized. when cell were grown in glucose, binding was inhibited 50% relative to extracts from cells grown with succinate as carbon source . this inhibition could be relieved by dialysis. | 1977 | 192718 |
| characterization of surface glycoproteins of mouse lymphoid cells. | we have labeled exposed surface glycoproteins of mouse lymphoid cells by the galactose oxidase-tritated sodium borohydride technique. the labeled glyco-proteins were separated by polyacrylamide slab gel electrophoresis and visualized by autoradiography (fluorography). the major thymocyte surface proteins have molecular weights of 170,000 and 125,000. thymocytes from tl antigen-positive mouse strains showed an additional band with a molecular weight of 27,000. highly purified t lymphocytes contai ... | 1976 | 192730 |
| inactivation of classical and alternative pathway-activated bactericidal activity of human serum by sodium polyanetholsulfonate. | sodium polyanetholsulfonate (sps) at a final concentration of at least 250 microng/ml (0.025%) was required for inhibition of the bactericidal activity of 80% (vol/vol) of fresh human serum against "promptly serum-sensitive" strains of serratia marcescens and control strain escherichia coli c, i.e., for inhibition of the classical pathway of complement activation. in contrast, sps at 125 microng/ml (0.0125%) was sufficient for neutralization of the bactericidal activity of 80% (vol/vol) fresh hu ... | 1977 | 192756 |
| microcalorimetry as a tool for evaluation of blood culture media. | evaluation of optimal compositions of blood culture media has called for extensive and laborious work in comparative studies of large series of clincal specimens. bacterial growth is accompanied by heat production, and calorimetry provides an analytical tool for its detection and quantification. a twin microcalorimeter of the heat conduction type was used to register heat effects in experimentally infected blood cultures. when studying escherichia coli and staphylococcus aureus, larger heat effe ... | 1977 | 192760 |
| anaerobic bacteria in biliary disease in elderly patients. | gallbladder bile from 52 elderly subjects who had undergone biliary tract surgery was examined for the presence of bacteria. twelve patients had sterile bile, 18 specimens of bile yielded anaerobes as well as aerobes, and 22 yielded aerobic bacteria only. escherichia coli was the most commonly isolated organism (30 strains). bacteroides fragilis was the most frequently encountered anaerobic bacterium and was found in 15 patients. the klebsiella-enterobacter group was the second most commonly iso ... | 1977 | 192815 |
| the activity of polymyxins against escherichia coli in an in-vitro model of the urinary bladder. | the activities against a strain of escherichia coli of polymyxin b, colistin (polymyxin e) and their sulphomethyl derivatives sulphomyxin and colistin sulphomethate have been examined in an in-vitro model of the urinary bladder under conditions similar to those that may operate in the therapeutic situation. in the dynamic conditions of the model, polymyxins exhibited a reduced activity against e. coli in comparison with activity against exponentially growing cultures in a static system. neverthe ... | 1977 | 192891 |
| gene cloning for the isolation of enzymes of membrane lipid synthesis: phosphatidylserine synthase overproduction in escherichia coli. | we have screened a bank of 2000 e. coli strains carrying hybrid cole1 plasmids [clarke, l. & carbon, j. (1976) cell 9, 91-99] for those that correct the temperature sensitivity of a mutant in cdp-1,2-diacyl sn-glycerol:l-serine o-phosphatidyltransferase (ec 2.7.8.8, phosphatidylserine synthase). two hybrid plasmids of this kind (plc34-44 and plc34-46) were identified and characterized. strains carrying these plasmids overproduce the synthase by 6- to 15-fold, as demonstrated by assays of extract ... | 1977 | 193099 |
| functioning of purine salvage pathways in escherichia coli k-12. | | 1977 | 193369 |
| comparison of the effects of mecillinam and 6-aminopenicillanic acid on proteus mirabilis, escherichia coli, and staphylococcus aureus. | single strains of proteus mirabilis, escherichia coli, and staphylococcus aureus were grown on filter membranes placed on agar containing concentration series of mecillinam (fl 1060), 6-aminopenicillanic acid (6-apa), or ampicillin. p. mirabilis and e. coli were also exposed to combinations of mecillinam or 6-apa with ampicillin. colony-forming units were counted, and cells were examined by interference phase-contrast and transmission electron microscopy. mecillinam and 6-apa were very effective ... | 1977 | 193439 |
| isolation and characterization of nonhistone chromosomal protein c-14 which stimulates rna synthesis. | the nonhistone chromatin protein, c-14, was extracted from chromatin of novikoff hepatoma ascites cells and isolated in high purity as shown by its migration as a single dense spot on two-dimensional polyacrylamide gels. its mobility on sodium dodecyl sulfate gels is consistent with a molecular weight of approximately 70 000. the amino acid composition shows that protein c-14 has an acidic:basic amino acid ratio of 1.8. its amino terminal amino acid is lysine. protein c-14 stimulated the incorpo ... | 1977 | 193558 |
| couplings between the sites for methionine and adenosine 5'-triphosphate in the amino acid activation reaction catalyzed by trypsin-modified methionyl-transfer rna synthetase from escherichia coli. | | 1977 | 193563 |
| lipoamide dehyrogenase immobilized on porous glass. | lipoamide dehydrogenase (nadh:lipoamide oxidoreductase, ec 1.6.4.3) isolate from pig heart and escherichia coli was covalently coupled by both diazonium and amide bonds to controlled pore glass beads (96% silica). when the enzyme was immobilized in the presence of nad+, the enzyme no longer exhibited its normal requirement for nad+ for full activity. if the immobilized enzyme was then treated with nadase, the requirement for nad+ was restored. enzyme immobilized in the absence of nad+ exhibited ... | 1977 | 193568 |
| purification and molecular properties of the amp-activated pyruvate kinase from escherichia coli. | the amp-activated pyruvate kinase (atp:pyruvate 2-o-phosphotransferase, ec 2.7.1.40) from escherichia coli has been purified 200 times through a three-step procedure which gives a homogeneous preparation with a specific activity of 110. the enzyme appears to be a tetramer of molecular weight 190 000. subunits (molecular weight 51 000) show a single amino-terminal amino acid (serine) and appear as a single band in polyacrylamide gel electrophoresis in sodium dodecyl sulphate. the enzyme crystalli ... | 1977 | 193572 |
| [formation of cyclic adenosine-3',5'-monophosphate in phagocytosis]. | the content of camp in the phagocytizing macrophages increased, especially in the phagocytosis of live microbes. camp formed in phagocytosis was determined in the incubation medium, whereas in the cells its content remained practically unchanged. in the administration of e. coli 055 to the germ-free guinea pigs the concentration of camp was found to be increased in the mucosa cells of the small intestine and in the blood serum; this fact indicated that adenylcyclase system participated in the re ... | 1976 | 193592 |
| direct serological assay for the heat-labile enterotoxin of escherichia coli, using passive immune hemolysis. | sheep erythrocytes sensitized with the heat-labile enterotoxin (lt) of escherichia coli exhibited passive immune hemolysis (pih) when exposed to specific antitoxin and complement. thus, pih serves as the basis for an in vitro serological assay for lt that is sufficiently specific and sensitive to differentiate lt-positive and lt-negative e. coli isolates. the pih assay for e. coli lt has been performed with the standard microtiter system and also by a tube method employing the spectrophotometri ... | 1977 | 193793 |
| determination of the nucleotide sequence of part of the regulatory region for the galactose operon from escherichia coli. | we have determined the sequence of 59 base pairs in the dna preceding the site for initiation of transcription in the galactose operon. dna from a lambdagal transducing phage was digested with restriction endonucleases to obtain a dna fragment from the gal regulatory region. this fragment extends from 59 base pairs prior to the transcription initiation site through the 45 base pairs which specify the 5'-terminal sequence of gal mrna. analyses of rna transcripts derived from this fragment and a v ... | 1977 | 193835 |
| specificity of initiation of transcription of simian virus 40 dna i by escherichia coli rna polymerase: identification and localization of five sites for initiation with [gamma-32p]atp. | simian virus 40 (sv40) dna i was transcribed with escherichia coli rna polymerase in the presence of gamma-32p-labeled ribonucleoside triphosphates in order to investigate the specificity of initiation of in vitro transcription. atp and gtp served as predominant initiating nucleotides, the former being incorporated about twice as much as the latter. cleavage of [gamma-32p]atp-labeled sv40 complementary rna (crna) with t1 rnase followed by homochromatographic analysis of the resultant 5' initiati ... | 1977 | 194061 |
| asbestos and glass fibres in bacterial mutation tests. | asbestos fibres are carcinogenic in man and experimental animals but fine glass fibres are known, at present, only to be carcinogenic in experimental animals. asbestos and glass fibres have been studied in mutation tests using auxotrophic strains of escherichia coli and salmonella typhimurium. the mutagenic activities of the positive control mutagens ultraviolet light, potassium chromate, ethyl methanesulphonate and benzo(a)pyrene were detected in the experiments. however, no mutagenic activity ... | 1977 | 194149 |
| nucleotide sequence of the restriction fragment hind f-eco ri2 of sv40 dna. | the nucleotide sequence of the sv40 genome region between the hind k fragment and the eco ri cleavage site has been determined by a combination of three different approaches : analysis of rna products obtained by transcription with escherichia coli dna dependent rna polymerase, partial degradations with snake venom exonuclease and base-specific chemical degradation of 5'-terminal labeled restriction fragments. this nucleotide sequence shows only one open reading frame and allows the deduction of ... | 1977 | 194225 |
| the release of endonuclease i from escherichia coli by a new cold shock procedure. | | 1976 | 194597 |
| preferential enhancement of ige antibody formation by bordetella pertussis. | preferential enhancement of ige antibody response was observed in balf/c mice by the administration of bordetella pertussis with antigen (dnp-salmonella). correlation between b cell mitogenic activity and adjuvant action among b. pertussis, salmonella, lipopolysaccharide of escherichia coli and ficoll was examined but was not found. thymus-derived cells seemed necessary to develop adjuvant action of b. pertussis since antibody response in athymic nude mice was not influenced by b. pertussis. hel ... | 1977 | 194843 |
| some properties of a mutant strain of escherichia coli requiring high concentrations of 2-methyl-4-amino-5-hydroxymethylpyrimidine. | | 1977 | 195024 |