| effect of leukocyte hydrolases on bacteria. xv. inhibition by antibiotics, metabolic inhibitors, and ultraviolet irradiation of the release by leukocyte extracts, trypsin, and lysozyme of lipopolysaccharide from gram-negative bacteria. | leukocyte extracts, trypsin, and lysozyme are all capable of releasing the bulk of the lps from s. typhi, s. typhimurium, and e. coli. bacteria which have been killed by heat, ultraviolet irradiation, or by a variety of metabolic inhibitors and antibiotics which affect protein, dna, rna, and cell wall synthesis no longer yield soluble lps following treatment with the releasing agents. on the other hand, bacteria which are resistant to certain of the antibiotics yield nearly the full amount of so ... | 1979 | 92459 |
| altered phospholipid composition in mutants of escherichia coli sensitive or resistant to organic solvents. | mutants of escherichia coli with altered resistance to low molecular weight organic solvents were isolated. solvent-resistant mutants showed a decrease in the ratio of phosphatidylethanolamine to the anionic phospholipids (phosphatidylglycerol and cardiolipin) relative to the wild-type, whereas solvent-sensitive strains showed an increase. reversion studies on representative mutants demonstrated that the phenotypic response to solvents and the changes in phospholipid composition were genetically ... | 1979 | 92527 |
| correlation between the capacity of bacterial lipopolysaccharide to supress experimental allergic encephalomyelitis and its mitogenic activity for lymph node cells in guinea pigs. | protection of guinea pigs from experimental allergic encephalomyelitis (eae) was attempted using bacterial lipopolysaccharide (lps) from 4 sources. the ability of these lps to induce dna synthesis in guinea pig lymph node (ln) cells in vitro was also investigated. it was found that there existed a good correlation between the capacity of lps to suppress eae and their degree of mitogenic activities for ln cells. lps from escherichia coli 0111:b4 (ec-lps), which was most effective in suppressing e ... | 1979 | 92530 |
| the accessibility of antigenic determinants of ribosomal protein s4 in situ. | antibodies to escherichia coli ribosomal protein s4 react with s4 in subribosomal particles, eg, the complex of 16s rna with s4, s7, s8, s15, s16, s17, and s19 and the ri reconstitution intermediate, but they do not react with intact 30s subunits. antibodies were isolated by three different methods from antisera obtained during the immunization of eight rabbits. some of these antibody preparations, which contained contaminant antibodies directed against other ribosomal proteins, reacted with sub ... | 1979 | 92615 |
| cytotoxic enteropathogenic escherichia coli. | | 1979 | 92636 |
| effect of escherichia coli endotoxin on the developing rat liver. i. giant cell induction and disruption in protein metabolism. | | 1979 | 92781 |
| drug resistance in escherichia coli isolated from diarrhoeic piglets. | | 1979 | 92850 |
| a minor species of escherichia coli trna specific for leucine is able to decode poly-u in a cell-free system because of a high affinity of its anticodon for uuu sequence [proceedings]. | | 1979 | 92961 |
| asymmetric transcription of the globin genes by escherichia coli rna polymerase in isolated mouse foetal liver chromatin or nuclei [proceedings]. | | 1979 | 92966 |
| antigenic similarity of morphologic type ciii1 bacteriophages. | the aim of the study was to demonstrate antigenic differentiation among bacteriophages belonging to the same morphologic type--ciii1 according to krzywy and slopek or a2 according to ackermann. twenty-six bacteriophages which multiplied on various strains of bacteria of the genera escherichia, shigella and klebsiella, were studied. serologic tests were done by the quantitative complement fixation test. immune sera against 5 phi e. coli. d8 sh. flexneri, g35 sh. sonnei and kl7 klebsiella bacterio ... | 1979 | 92976 |
| b-cell subsets responsive to fluorescein-conjugated antigens. iii. differential effect of e. coli lipopolysaccharide on t-dependent and t-independent responses in vivo. | the effect of e. coli lipopolysaccharide (lps) on the induction of both hapten-specific immunity and tolerance was studied in an in vivo system utilizing putative t-cell dependent (td) or t-cell independent (ti) challenge antigens. the administration of lps 1 day prior to challenge preempted the response of c3d2 mice to a td antigen (fl-klh) but had little effect on the response to fl-ficoll, a ti antigen. lps did not affect the responsiveness of c3h/hej mice, an lps-unresponsive strain, to eith ... | 1979 | 93080 |
| effect of colicins ia and e1 on ion permeability of liposomes. | colicins ia and e1 are shown to inhibit the formation and bring about the collapse of a potassium diffusion potential imposed across the membrane of liposomes prepared from soybean or escherichia coli phospholipids. such depolarization results from a colicin-induced increase in membrane ion permeability. colicins e2 and e3 do not depolarize such membranes. in addition to the colicin ia-induced rapid efflux of preloaded rubidium, sodium, phosphate, or choline from liposomes, a slower efflux of pr ... | 1979 | 93288 |
| evidence in vitro for a participation of the arginine repressor in cumulative repression of escherichia coli carbamoylphosphate synthase [proceedings]. | | 1979 | 93462 |
| function of individual e. coli 30 s ribosomal proteins as determined by in situ immunospecific neutralization: a tentative classification. | the accessibility of each 30s subunit protein to their cognate antibodies (igg or fabs) having been previously well established, the effect of their in situ specific neutralization by monovalent igg fragments (fabi) are reported for five reactions: 1) t4 and r17 rna directed protein synthesis: 2) polyphenylalanine synthesis: 3) enzymatic phe-trna binding in the presence of 30s + 50w subunits: 4) fmet-trnaf binding to the 30s subunit in the presence of initiation factors if1, if2, if3; 5) couplin ... | 1979 | 93493 |
| serum antibodies to escherichia coli in subjects with ulcerative colitis. | | 1979 | 93528 |
| response to bleomycin of escherichia coli mutants deficient in dna repair. | the effect of bleomycin on the colony forming ability of escherichia coli k12 strains in exponential growth at 37 degrees c was not affected by introducing reca13, lexa1, pola1 and uvra6 mutations. for cells starved for amino acids, wild type strains became ten-fold more resistant to bleomycin, but again introducing lexa1, pola1 and uvra6 strains did not change the effect on colony forming ability; however, starved reca13 cells were now four-fold more sensitive. strains with reca13, lexa1 and po ... | 1979 | 93597 |
| the effect of an escherichia coli regulatory mutation on transfer rna structure. | | 1979 | 93644 |
| base-pairing between distant regions of the escherichia coli 16 s ribosomal rna in solution. | | 1979 | 93645 |
| crosslinking studies on the organization of the 16 s ribosomal rna within the 30 s escherichia coli ribosomal subunit. | | 1979 | 93646 |
| determining the polarity of the map of crosslinked interactions in escherichia coli 16 s ribosomal rna. | | 1979 | 93647 |
| the effects of mefloquine on escherichia coli. | | 1979 | 93673 |
| relative opsonic and protective activities of antibodies against k1, o and lipid a antigens of escherichia coli. | the k1 escherichia coli capsular antigen has been implicated as a virulence factor because of the frequency of isolation of k1 containing strains from certain invasive human infections. in the study of the interaction between k1 strains, normal human polymorphonuclear cells (pmns) and fresh human serum, we have found varying susceptibility to phagocytosis and killing; thus, the in vitro opsonophagocytic and in vivo protective role of k1, somatic o and core glycolipid antibodies remain unclear. w ... | 1979 | 93778 |
| a method for isolation of escherichia coli mutants with aberrant rna methylation using translocatable drug resistance elements. | | 1979 | 93836 |
| triggering of autolytic cell wall degradation in escherichia coli by beta-lactam antibiotics. | a biochemical method was developed to quantitatively compare the effectiveness of beta-lactams in triggering murein degradation (autolysin activity) in escherichia coli. bacteria prelabeled in their cell walls with radioactive diaminopimelic acid in growth medium were exposed for 10 min to the antibiotics at the appropriate minimal growth inhibitory concentrations and at multiples of these values, and the rate of cell wall degradation was followed during subsequent penicillin-binding protein (pb ... | 1979 | 93877 |
| in vivo transcriptionally coupled assembly of escherichia coli ribosomal subunits. | | 1979 | 94102 |
| models for decay of escherichia coli lac messenger rna and evidence for inactivating cleavages between its messages. | | 1979 | 94103 |
| study of the internal structure of escherichia coli ribosomes by neutron and x-ray scattering. | | 1979 | 94105 |
| structure of the rna portion of the rna-linked dna pieces in bacteriophage t4-infected escherichia coli cells. | | 1979 | 94107 |
| isolation and characterisation of a strain carrying a conditional lethal mutation in the cou gene of escherichia coli k12. | a strain which carries a mutation conferring clorobiocin resistance and temperature sensitivity for growth was isolated from escherichia coli k12. genetic mapping and the molecular weight of the gene product suggest that the mutation is in the cou gene, specifying a sub-unit of dna gyrase. nuclear organisation and segregation and placement of septa are grossly abnormal in the mutant at 42 degrees c. rna synthesis and initiation of dna replication are also affected at the restrictive temperature ... | 1979 | 94144 |
| stringent control in e. coli. | | 1979 | 94252 |
| relationships among raffinose plasmids determined by the immunochemical cross-reaction of their alpha-galactosidases. | plasmid-encoded alpha-galactosidase served as a marker enzyme for the recognition and comparison of raffinose (raf) plasmids present in strains of escherichia coli. immunochemical relationships were established among raf plasmids of 39 independent isolates from man and domestic animals (from three continents) by using antiserum against alpha-galactosidase. immunodiffusion revealed three serological subclasses of alpha-galactosidase, which are correlated with the biological and geographical origi ... | 1979 | 94343 |
| effects of subminimal inhibitory concentrations of ampicillin, chloramphenicol, and nitrofurantoin on the attachment of escherichia coli to human uroepithelial cells in vitro. | an in vitro system with epithelial cells of the human urinary tract and escherichia coli isolated from the urine of pateints with acute pyelonephritis was used for tests of the effect of antibacterial agents on bacterial adhesion. e. coli treated with subminimal inhibitory amounts of ampicillin attached less than untreated control bacteria. subminimal inhibitory amounts of chloramphenicol and nitrofurantoin had no effect on adhesion of the 15 strains of e. coli tested. the combination of bacteri ... | 1979 | 94452 |
| [immunofluorescent diagnosis of entamoeba histolytica trophocoites in preserved stool specimens of patients (author's transl)]. | a fixative and examination technique is described for identification of entamoeba histolytica trophocoites in faeces with the aid of the indirect immunofluorescence technique. magnaforms in bloody-dysenteric specimens and minutaforms in spontaneous or saline purged specimens give equally good fluorescence. the specifity of the rabbit antiserum against axenically grown e. hist. is good: there is strong positive reaction only with trophocoites of e. hist. weak crossreactions are encountered with t ... | 1979 | 94475 |
| [effect of temperature on rna synthesis in escherichia coli crt 266 (dna bts) following infection with bacteriophage t3]. | infection of the temperature-sensitive e. coli crt 266 (dnabts) with t3-phages at the temperature of 30 degrees c and 35 degrees c, respectively, induced t3-specific rna synthesis with a maximum rate at 7 min (30 degrees c) and 4.5 min (35 degrees c) after infection. at temperatures above 40 degrees c no t3-induced rna synthesis could be observed. infection of e. coli cr 34--45 (dnab+) with t3 phages at 30 degrees c, 35 degrees c and at temperatures above 40 degrees c, however, produced t3-speci ... | 1979 | 94483 |
| dependence of macromolecular composition and morphology of streptomyces hygroscopicus on specific growth rate. | the dependence of macromolecular composition and morphology of streptomyces hygroscopicus on specific growth rate micron was investigated. the percentage of dna on dry weight (%dna) is constant, % protein is also nearly independent of micron whereas %rna rises considerably with increasing micron, regarding mycelia grown in glucose-limited and ammonium-limited continuous cultures as well as in discontinuous cultures with various carbon sources. it is probable that the overall synthesis of dna, rn ... | 1979 | 94484 |
| identification of bacteroides fragilis by indirect immunofluorescence. | rabbit antiserum against live or heat-killed bacteroides fragilis nctc 9343 bacteria was titrated against hot phenol water-extracted polysaccharide antigens from five different species of the 'b. fragilis group' of bacteria using an enzyme immunoassay and shown to be specific for the b. fragilis nctc 9343 polysaccharide. when the antiserum was used in indirect immunofluorescence, 97.1% of 244 b. fragilis strains were correctly identified. only 8 of the other 312 bacteroides strains were stained ... | 1979 | 94651 |
| [host range relationship of bacteriophages t3 and t7 with escherichia coli k 12 strains]. | the closely related phages t3 and t7 exhibit different growth patterns on escherichia coli w hosts cells (e. coli k12 derivatives). t7 grows normally while t3 does not adsorb. t3hw mutants displaying a t7-like host range were isolated and described. | 1979 | 94721 |
| transferable drug resistance of escherichia coli isolated from infant diarrhoea. | the resistance to several drugs was determined in 29 pathogenic strains of escherichia coli (026, 055 and 0111) isolated from infant diarrhoea and 18 non-pathogenic e. coli strains isolated from the same individuals. both pathogenic and nonpathogenic strains were resistant to at least 1 to 10 drugs, but only in four cases resistance patterns of the pathogenic strains were identical with those of non pathogenic ones. the majority of the strains were resistant to sulfonamide, tetracycline, ampicil ... | 1979 | 94745 |
| [effects of different concentrations of chloramphenicol on rna synthesis in e. coli]. | in the presence of 2 microgram/ml chloramphenicol the rate of total rna synthesis increases 1,6-fold, while that of rrna synthesis--2,5--3,0-fold. other ribosomal antibiotics, e.g. oxytetracycline, neomycin and puromycin, as well as chloramphenicol stimulate the synthesis of rna while not causing a complete inhibition of the protein synthesis. intensive stimulation of the rate of rrna synthesis with low concentrations of chloramphenicol may be due to a decrease of intracellular concentration of ... | 1979 | 94838 |
| [inhibition of rna synthesis in vitro by antibodies against mononucleotides]. | antibodies against purine nucleotides were obtained from rabbits immunized with conjugates of bovine serum albumine with amp or gmp. the antibodies purified by affinity chromatography on nucleoside monophosphate-human serum albumine-sepharose columns inhibited rna synthesis on native t4 phage dna by e. coli rna polymerase. the inhibition of transcription was due mainly to inhibition of the initiation stage of rna synthesis. | 1979 | 94937 |
| [differences in sensitivity of t3, t7, t4 and lambda phages to bleomycin and phleomycin]. | in contrast to phage lambda the phages t3, t7 and t4 are not inhibited by as much as 150 microgram bleomycin/ml, while the chemically related antibiotic phleomycin increasingly inhibits the propagation of the phages in the order t4-t3-lambda. 20 microgram phleomycin/ml inhibit t3 by 95%. the resistance against bleomycin is surprising, because 10 microgram bm/ml block completely the colony-forming capacity of the host bacterium. the drug resistance of the phage growth correlates with the weak dec ... | 1979 | 94958 |
| effect of beta-indoleacetic acid on rna and protein synthesis in escherichia coli. | the effect of different concentrations of beta-indoleacetic acid (iaa) on rna and protein synthesis and the stability of associations of e. coli ribosomes at 3 mm mg2+ was investigated. iaa in a concentration of 100 microgram/ml had a slight stimulatory effect on the incorporation of [14c]leucine into proteins and stimulated the incorporation of [14c]uracil into the rna of intact cells more noticeably. in the presence of 2500 microgram/ml of the auxin rna synthesis was inhibited by 65% and prote ... | 1979 | 95100 |
| ribonucleotides in dna newly synthesised in 3t6 cells in vivo. | within the field of dna replication, considerable interest has focused in recent years on the mechanism of initiation of synthesis of dna molecules. in vitro replication systems from escherichia coli have been instrumental in uncovering a priming function fo9r ribonucleotides on the earliest intermediates of dna polymerisation in vitro and in identifying the proteins involved. in vitro replication systems from mammalian cells that permit the use of the phosphate-transfer method for detection of ... | 1979 | 95207 |
| [action of a dithiocarbamate (zinebe) on the liver biosynthesis of rna and proteins in the rat (author's transl)]. | zineb (zinc ethylene bisdithiocarbamate) inhibits the transcriptional activity of an in vitro system functioning with either rna polymerases of isolated rat liver nuclei or purified e. coli rna polymerase. zineb also inhibits the in vitro aminoacid incorporation mediated by a polysomal standard system, by interacting with some ph 5 enzyme components(s). when rats fed a balanced semi-synthetic diet containing zineb (5 200 mg/kg) for ten weeks, one may observe a decrease in the rna and protein syn ... | 1978 | 95332 |
| [nucleic acids in the liver of rat treated with "e. coli" o 127 lipopolysaccharide (author's transl)]. | the authors have studied the variations of nucleic acids, proteins and histological aspect in the liver of rats, treated with 1 mg of e. coli ) 127 lipopolysaccharide and killed at 24th, 48th, 72th, 96th hour after the inoculation. the endotoxin determines an increase of nucleic acids and a reduction of hepatic proteic contents. the histological observation shows throw-back phenomenons of the hepatocyte with hyperplasy and hypertrophy of kupffer cells at 24th hour, while at following intervals t ... | 1979 | 95476 |
| phenethyl alcohol inhibition of sn-glycerol 3-phosphate acylation in escherichia coli. | in vivo and in vitro experiments were performed to determine how phenethyl alcohol (pea) inhibits phospholipid synthesis in escherichia coli. this drug drastically reduced the rate of incorporation of sn-glycerol 3-phosphate into the phospholipids of an sn-glycerol 3-phosphate auxotroph. pea also reduced the rate of fatty acid incorporation into the phospholipids of a fatty acid auxotroph. the kinetics of pea inhibition of the rate of incorporation of sn-glycerol 3-phosphate were almost identica ... | 1977 | 95658 |
| stringent regulation of the synthesis of a transfer ribonucleic acid biosynthetic enzyme: transfer ribonucleic acid(m5u)methyltransferase from escherichia coli. | this paper describes the regulation of a transfer ribonucleic acid (trna) biosynthetic enzyme, the trna(m5u)methyltransferase (ec 2.1.1.35). this enzyme catalyzes the formation of 5-methyluridine (m5u, ribothymidine) in all trna chains of escherichia coli. partial deprivation of charged trnaval can be imposed by shifting strains carrying a temperature-sensitive valyl-trna ligase from a permissive to a semipermissive temperature. by using two such strains differing only in the allelic state of th ... | 1977 | 95660 |
| repetitive dna in escherichia coli: multiple sequences complementary to small stable rnas. | radioactively labeled 4.5s, 6s, and 10s rnas from escherichia coli were hybridized to ecori fragments from the e. coli genome. each of these molecules bound to more than one dna fragment. cot curve analysis of the kinetics of the annealing of these rnas to denatured e. coli dna suggests that the dna corresponding to each of these molecules is reiterated in the genome. these experiments also suggest that these reiterated sequences are non adjacent. | 1979 | 95791 |
| [synthesis and study of biospecific sorbents for isolating and purifying l-asparaginase from escherichia coli]. | amino acid and oligoamide derivatives of d-asparagine and l-asparaginic acid (l-asparaginase inhibitors) have been synthesized. an increase in the hydrophobic capacity of the modified inhibitor increases the inhibition constant. once the modified inhibitor binds with sepharose 6b, the length of the spacer (a chain of atoms attaching the inhibitor to the polymer matrix) determines affinity of the sorbent for l-asparaginase. on these sorbents affinity shifts from ph optimum of the enzyme activity ... | 1979 | 95826 |
| inhibition of leucyl-trna synthetase in escherichia coli by the cytostatic 5,8-dioxo-6-amino-7-chloroquinoline. | at concentrations of 1-1.6 mug/ml, 5,8-dioxo-6-amino-7-chloroquinoline causes auxotrophy for leucine in escherichia coli mre 600. with increasing concentrations of this quinone additional amino acids are required for growth. the amount of leucine in the pool of free amino acids is not decreased after treatment of e. coli with the quinone. transfer rnaleu, however, is charged with leucine less than 10% in quinone-treated cells of e. coli, whereas in control cells the degree of aminoacylation is a ... | 1975 | 95889 |
| mezlocillin: a new acyl ureidopenicillin. antimicrobial activity and combination effects with four aminoglycoside antibiotics. | mezlocillin (baypen), carbenicillin and mezlocillin combined with gentamicin, sisomicin, tobramycin and amikacin, respectively, were tested in vitro against 325 fresh clinical isolates of pathogenic gram-negative bacteria using the tube dilution procedure. the new acyl ureidopenicillin has a greater antimicrobial activity than carbenicillin against nearly all species tested. the comparison of the effectiveness of the mezlocillin-aminoglycoside combinations demonstrates the superiority of mezloci ... | 1978 | 95925 |
| characterisation of the binding of virginiamycin s to escherichia coli ribosomes. | virginiamycin s is an inhibitor of protein synthesis in vivo. in this paper we show by equilibrium dialysis that it binds specifically to the 50-s subunit of escherichia coli ribosomes, with one binding site per subunit. this binding is not altered by the presence of chloramphenicol, tetracycline or puromycin but is competed for by erythromycin. using the splitting-reconstitution method, it could be demonstrated that protein l16 is absolutely required for the binding of virginiamycin s to the 50 ... | 1978 | 95947 |
| mechanistic aspects of the transfer of nascent periplasmic proteins across the cytoplasmic membrane in escherichia coli. | | 1978 | 95950 |
| cloned seventeen-nucleotide-long synthetic lactose operator is biologically active. | a 17-nucleotide-long synthetic dna molecule constituting the minimal recognition sequence of the lactose operator has been cloned in e. coli using the vehicle pbr313 and a synthetic hindiii adaptor. the clones containing the lac-pbr313 hybrid dna constitutively produced beta-galactosidase. the level of beta-galactosidase was high and comparable to that obtained in cells carrying a 21-nucleotide-long synthetic lac operator on pmb9 plasmid or cells carrying a natural lac operator on pop203-1 plasm ... | 1978 | 95988 |
| effects of low temperature on in vivo and in vitro protein synthesis in escherichia coli and pseudomonas fluorescens. | the effects of temperature on protein synthesis by escherichia coli, a mesophile, and pseudomonas fluorescens, a psychotroph, were investigated by using whole-cell and cell extract preparations. after shifts to 5 degrees c, protein was synthesized at a slowly decreasing rate for 1 h by both organisms, after which p. fluorescens synthesized protein at a new rate corresponding to its 5 degrees growth rate, in contrast to e. coli which did not synthesize protein at a measurable rate. in vitro prote ... | 1978 | 96102 |
| energy metabolism of rickettsia typhi: pools of adenine nucleotides and energy charge in the presence and absence of glutamate. | the obligate intracellular bacterium rickettsia typhi was examined for its ability to generate and maintain an adenylate energy charge in an extracellular environment. freshly purified organisms were incubated, at 34 degrees c and ph 7.4, with or without glutamate and various other metabolites, and the levels of atp, adp, and amp were determined. of the metabolites tested, glutamate and glutamine were the most effective for the generation of atp. in the presence of glutamate, there was a rapid i ... | 1978 | 96104 |
| methods for storage of antimicrobial effectiveness test inoculum suspensions below freezing. | studies were conducted to determine the suitability of storage below freezing of some antimicrobial effectiveness test inoculum organisms: staphylococcus aureus, escherichia coli, pseudomonas aeruginosa, and candida albicans. several solutions used for protecting microorganisms subjected to storage below freezing were compared. comparison of 10% dextrose with other solutions (distilled water; 0.07 m phosphate buffer, h 7.0, with 15% glycerol; and 0.07 m phosphate buffer, ph 7.0, with 7.5% dimeth ... | 1978 | 96247 |
| transposition of pseudomonas toluene-degrading genes and expression in escherichia coli. | | 1978 | 96356 |
| activity of azlocillin and mezlocillin against gram-negative organisms: comparison with other penicillins. | the activities of azlocillin and mezlocillin were compared with those of carbenicillin, ticarcillin, and pirbenicillin against a wide range of gram-negative organisms. the two new drugs were considerably more active than carbenicillin against klebsiella species and escherichia coli. carbenicillin was twice as active against proteus mirabilis as mezlocillin and four times as active as azlocillin. against pseudomonas aeruginosa, azlocillin was eight times as active as carbenicillin. azlocillin and ... | 1978 | 96726 |
| plasmid-determined resistance to boron and chromium compounds in pseudomonas aeruginosa. | plasmids determining resistance to arsenic, mercury, silver, and tellurium compounds in escherichia coli and pseudomonas aeruginosa were tested for resistance to 40 other metal compounds. resistance to trivalent boron and hexavalent chromium compounds was a property of certain p. aeruginosa plasmids. | 1978 | 96730 |
| enzyme secretion in e. coli k12 : studies on alkaline phosphatase synthesis using an unsaturated fatty-acid auxotroph. | | 1978 | 96837 |
| studies on the negative circular dichroic bands around 297 nm of ribosomes from bacterial cells. | the small negative cd bands around 297 nm of isolated 30-s and 50-s ribosomal subunits were precisely measured for three bacteria, bacillus stearothermophilus, bacillus subtilis and escherichia coli q 13. the intensities of the negative cd bands of 30-s subunits were always much greater than those of 50-s subunits irrespective of the bacterial strains, which may be related to the difference in comformations of rrnas and proteins in the complexes between these subribosomal particles. the dissocia ... | 1978 | 96858 |
| studies on transfer rna from mycobacteria. | active preparations of trna and aminoacyl-trna synthetases have been isolated from exponentially growing cells of mycobacterium smegmatis and mycobacterium tuberculosis h37rv. though the aminoacyl-trna synthetases of older cells retain their activity, the trnas seem to undergo modification and show poorer activity. the mycobacterial enzyme preparations catalyse homologous and heterologous aminoacylation between trna from the two species (m. smegmatis and m. tuberculosis h37rv) or from escherichi ... | 1978 | 96929 |
| experimental evolution of a new enzymatic function. ii. evolution of multiple functions for ebg enzyme in e. coli. | the evolution of ebgo enzyme of escherichia coli, an enzyme which is unable to hydrolyze lactose, lactulose, lactobionate, or galactose-arabinoside effectively, has been directed in successive steps so that the evolved enzyme is able to hydrolyze these galactosides effectively. i show that in order for a strain of e. coli with a lacz deletion to evolve the ability to use lactobionate as a carbon source, a series of mutations must occur in the ebg genes, and that these mutations must be selected ... | 1978 | 97169 |
| demonstration of k88ac and k88ab antigens of escherichia coli by means of immunoelectrophoresis and immunodiffusion. | five strains of escherichia coli were tested for the presence of the k88ac or k88ab antigens by immunoelectrophoresis and immunodiffusion. the k88ac antigen of 0a2 and sojka abbotstown gave an anodic line in the immunoelectrophoresis test and a line in immunodiffusion with homologous k88ac antisera. the k88ab antigens of 0g7, 0e68, and moon 263 also gave anodic lines in immunoelectrophoresis, and were detectable by immunodiffusions. the 0 groups of these strains were also demonstrated by immunoe ... | 1978 | 97237 |
| post-transcriptional modifications of the anticodon loop region: alterations in isoaccepting species of trna's during development in bacillus subtilis. | structural similarities of trna's were compared using three sets of isoaccepting species that had previously been shown to undergo significant changes in chromatographic elution properties as a function of developmental stage in bacillus subtilis. comparisons of the structures of the trna's were based on the composition of their modified nucleosides, comparisons of oligonucleotide elution profiles from rpc-5 columns, and two-dimensional electrophoretic fingerprint analysis of oligonucleotides. t ... | 1978 | 97263 |
| two bacteriophages which utilize a new escherichia coli major outer membrane protein as part of their receptor. | escherichia coli strain jf694 contains a new major outer membrane protein which we have called protein e (j. foulds, and t. chai, j. bacteriol. 133:1478-1483). two new bacteriophages, tc45 and tc23, were isolated that require the presence of protein e in the outer membrane of host cells for growth. both of these bacteriophages have a morphology similar to t-even bacteriophages but are distinct in properties such as plaque morphology, buoyant density, and burst size. although strain jf694, contai ... | 1978 | 97266 |
| f'-plasmid transfer from escherichia coli to pseudomonas fluorescens. | various f' plasmids of escherichia coli k-12 could be transferred into mutants of the soil strain 6.2, classified herein as a pseudomonas fluorescens biotype iv. this strain was previously found to receive flac plasmid (n. datta and r.w. hedges, j. gen microbiol. 70:453-460, 1972). ilv, leu, met, arg, and his auxotrophs were complemented by plasmids carrying isofunctional genes; trp mutants were not complemented or were very poorly complemented. the frequency of transfer was 10(-5). subsequent t ... | 1978 | 97267 |
| isolation of large bacterial plasmids and characterization of the p2 incompatibility group plasmids pmg1 and pmg5. | large plasmids from agrobacterium tumefaciens, salmonella typhimurium, escherichia coli, pseudomonas putida, and pseudomonas aeruginosa were routinely and consistently isolated using a procedure which does not require ultracentrifugation but includes steps designed to separate large-plasmid dna from the bacterial folded chromosome. it also selectively removes fragments of broken chromosome. a variety of large plasmids was readily visualized with agarose gel electorphoresis, including five betwee ... | 1978 | 97269 |
| tol is a broad-host-range plasmid. | we readily isolated insertions of the carbenicillin resistance element tn401 into the tol plasmid in pseudomonas putida. hybrid tol::tn401 plasmids stably express the cbr phenotype in pseudomonas aeruginosa and escherichia coli. whereas the replicative and conjugative functions are expressed in both hosts, the ability to grow on m-toluate is only expressed in the pseudomonas species. | 1978 | 97271 |
| repression of biotin biosynthesis in escherichia coli during growth on biotin vitamers. | a strain of escherichia coli in which the lacz gene was fused to the bioa promoter was constructed. colonies of this strain formed lac(+) colonies on low-biotin agar (1.6 to 4.1 nm) and lac(-) colonies on high-biotin agar (41 nm). this lac-bio fusion strain was used to study the question of whether cells growing on the biotin vitamers d-biotin-d-sulfoxide (bds) and dethiobiotin (dtb) generate enough biotin to give maximal repression of beta-galactosidase synthesis. repression by high concentrati ... | 1978 | 97277 |
| independence of proline chemotaxis and transport in bacillus subtilis. | values of ki for nine proline analogs as inhibitors of proline chemotaxis and of proline transport were determined. two of them inhibited transport at substantially lower concentrations than chemotaxis; two at substantially higher concentrations. moreover, mutants, believed to be in the component that binds proline, were isolated that showed a shift of km for transport to higher concentrations, one as much as 40-fold. however, chemotaxis was virtually unaffected. therefore, unlike galactose chem ... | 1978 | 97283 |
| characterization of an endoribonuclease, rnase n, from escherichia coli. | the properties of the enzyme ribonuclease n were investigated. by comparing the distribution in the cell of rnase n with the bonafide intracellular beta-galactosidase, and the periplasmic alkaline phosphatase enzymes, we showed that rnase n is an intracellular enzyme. since previous studies suggested that it is an endoribonuclease, it was compared to rnase iii, the only other known intracellular endoribonuclease in escherichia coli. using homopolymers and co-polymers we found that, while rnase i ... | 1978 | 97300 |
| recombinant plasmids capable to replication in b. subtilis and e. coli. | | 1978 | 97514 |
| new regulatory mutations affecting the expression of the threonine operon in escherichia coli k-12. | the promoter of the threonine operon was joined to the structural genes of the lac operon in escherichia coli k 12. the synthesis of beta-galactosidase was thus repressed by threonine plus isoleucine in the fusion strains. to isolate mutations which affect the expression of the threonine operon, alterations in the level of expression of the lacz gene were selected. a new type of regulatory mutation was discovered. | 1978 | 97515 |
| interactions of helium, oxygen, and nitrous oxide affecting bacterial growth. | helium at pressures of 20 to 70 atm in the presence of air found to stimulate growth of streptococcus faecalis, escherichia coli, and staphylococcus aureus, mainly by increasing the rate of exponential growth. however, at these same pressures, helium potentiated the growth-inhibitory actions of oxygen and nitrous oxide (n2o). oxygen was found to act essentially as an anesthetic gas in inhibiting growth of s. faecalis; its potency was approximately the same as that of n2o, and it acted additively ... | 1978 | 97828 |
| intestinal gradient of enterokinase activity in different species of animals. | the proximodistal gradient of enterokinase activity was studied in mucosal homogenates of the duodenum, jejunum, ileum, caecum (or megacaecum) and sigmoid flexure of various mammals. the study was carried out in groups of 5 monkeys, guinea pigs, dogs and rats and also in gnotobiological rats--conventional (n = 5), germ-free (n = 10) and monocontaminated (n = 5) with escherichia coli 0 86. enterokinase activity was likewise determined in duodenal mucosal homogenates prepared from material resecte ... | 1977 | 97929 |
| neonatal calf diarrhea caused by a virus that induces villous epithelial cell syncytia. | intestinal lesions caused by a virus serologically unrelated to the calf diarrheal rotavirus or coronavirus were studied in gnotobiotic calves. the virion purified from feces from infected calves was a fringed particle with a diameter of about 100 nm. the incubation period from time of inoculation per orum to onset of diarrhea in calves was as short as 8 hours. the viral infection in bacteria-free calves or calves not contaminated with pathogenic bacteria caused severe illness for only 24 hours. ... | 1978 | 98080 |
| hypoxic radiosensitizers: prospects for effective compounds with fewer toxic side-effects. | several radiosensitizing chemicals, including a family of simple nitroimidazoles, were examined in e. coli and compared with misonidazole for toxic side-effects on endpoints such as mutagenesis, cell killing and inhibition of the synthesis of the inducible enzyme beta-galactosidase. while all the compounds were similar to misonidazole or better in radiosensitization, marked differences in the various side effects were found. there results show that for e. coli it is possible to find compounds th ... | 1978 | 98175 |
| effects of various divalent cations on the survival of neisseria gonorrhoeae in liquid media. | the effect of various concentrations of divalent cations on survival of gonococci in liquid medium was studied. the growth of neisseria gonorrhoeae was inhibited by manganous chloride in concentrations above 1 x 10(-5)mol/l while the growth of control organisms such as neisseria meningitidis and escherichia coli was not inhibited by the same salt even at 1 x 10(-2)mol/l. copper sulphate, cobaltous nitrate, nickel chloride, and zinc sulphate also had deleterious effects on gonococci. magnesium ch ... | 1978 | 98204 |
| formylation of initiator trna methionine in procaryotic protein synthesis: in vivo polarity in lactose operon expression. | eucaryotic and procaryotic organisms differ in two aspects of their translation machinery: polycistronic messengers are expressed as a sequence of individual proteins only in procaryotes, and the initiation of protein synthesis proceeds with an initiator trna which is found to be modified (formylated) in procaryotes and not in eucaryotes. in the present study, we show that formylation is required in vivo for the coordinate expression of the escherichia coli lactose operon. our experiments are co ... | 1978 | 98518 |
| altered mrna metabolism in ribonuclease iii-deficient strains of escherichia coli. | the metabolism of mrna from the lactose (lac) operon of escherichia coli has been studied in ribonuclease (rnase) iii-deficient strains (rnc-105). the induction lag for beta-galactosidase from the first gene was twice as long, and enzyme synthesis was reduced 10-fold in one such mutant compared with its isogenic rnc+ sister; in the original mutant strain ab301-105, synthesis of beta-galactosidase was not even detectable, although transduction analysis revealed the presence of a normal lac operon ... | 1978 | 98520 |
| enzymatic excision of free hypoxanthine from polydeoxynucleotides and dna containing deoxyinosine monophosphate residues. | a dna glycosylase that releases free hypoxanthine by selective cleavage of dimp residues in polydeoxynucleotides and dna containing this nonconventional nucleotide is present in escherichia coli cell extracts. the partly purified enzyme, termed hypoxanthine-dna glycosylase, does not require divalent cations or phosphate for activity, and it acts more efficiently on double-stranded than on single-stranded substrates. the enzyme has properties different from either uracil-dna glycosylase or 3-meth ... | 1978 | 98523 |
| dihydrofolate reductase from amethopterin-resistant lactobacillus casei. sequences of the cyanogen bromide peptides and complete sequences of the enzyme. | the complete amino acid sequence of dihydrofolate reductase from an amethopterin-resistant strain of lactobacillus casei has been determined by sequence analysis of peptides produced by cleavage with cyanogen bromide, trypsin, staphylococcal protease, and myxobacter protease. comparison of this sequence with those of reductases from other bacterial sources shows that the enzymes are homologous. the lactobacillus casei reductase sequences shows a 29% sequence identity with that of the escherichia ... | 1978 | 98527 |
| l-asparaginase bound to collagen membranes: effect of glutaraldehyde crosslinking on stabilization of catalytic activity. | reconstituted bovine collagen has been used extensively in our laboratory as a carrier for immobilized e. coli l-asparaginase. the activity and catalytic stability of these collagen-asparaginase membranes can be altered substantially by conditions used in membrane crosslinking with glutaraldehyde. as the concentration of glutaraldehyde used in tanning is increased, the initial specific activity of collagen-asparaginase membranes decreased asymptotically to a limiting value. similar results occur ... | 1978 | 98529 |
| antibacterial functions of macrophages in experimental protein-calorie malnutrition. ii. cellular and humoral factors for chemotaxis, phagocytosis, and intracellular bactericidal activity. | cellular and humoral aspects of the antibacterial activity of macrophages during experimental protein-calorie malnutrition were studied. there were no defects in chemotaxis or bactericidal activity of cells from protein-deficient animals, although phagocytosis-associated oxygen consumption and hexose monophosphate shunt activity were depressed. however, marked impairment of humoral chemotactic factors generated in the peritoneal cavity by glycogen injection and of heatlabile serum opsonins for s ... | 1978 | 98599 |
| molecular cloning of the gene region coding for the chloroplast rrna of euglena gracilis. | e. gracilis chloroplast dna bam fragments e and d, coding for rrna were cloned separately using the plasmid pbr 322 as vector and e. coli as host. the newly constructed recombinant plasmids egcks 8 and egcks 11 (containing the bam hi fragments e and d respectively) were analysed and characterized by gel electrophoresis, electronmicroscopy and analytical ultracentrifugation. | 1978 | 98702 |
| evidence that f' lac replicates asynchronously during the cell cycle of escherichia coli b/r. | the replication of f' lac was studied in exponentially growing cultures of e. coli b/r. the cells were pulse induced for the synthesis of beta-galactosidase and their dna pulse labelled with 3h thymidine. the cells were then separated into age classes by centrifugation through a sucrose gradient in a zonal rotor. plasmide replication was measured in each age fraction by three methods: the rate at which beta-galactosidase could be induced, the amount of label incorporated into ccc plasmid dna whi ... | 1978 | 98704 |
| the activity of cephalosporins on beta-lactamase-producing neisseria gonorrhoeae. | the antibacterial activity of cephaloridine, cephalothin, cephalexin, cephradine, cefazolin, cefamandole, cefuroxime and cefoxitin was determined for six beta-lactamase-producing gonococci isolated in great britain and the usa. cefuroxime was most active against small and large inocula, then cefoxitin, while cephaloridine was least active. cefamandole was more active than cefazolin and cephalothin, but only on small inocula, and these three antibiotics, with the slightly inferior cephalexin and ... | 1978 | 98833 |
| the effect of complement depletion on bacterial lipopolysaccharide (lps)-induced hemodynamic and hematologic changes in the rhesus monkey. | lipopolysaccharide (lps) isolated from salmonella minnesota r595 or from escherichia coli 0111:b4 induces hypotension in rhesus monkeys with normal complement levels. this hypotension is accompanied by decreased total peripheral resistance. the depletion of c3 and terminal complement components by prior intraperitoneal administration of the anticomplementary protein cobra factor did not alter the hemodynamic changes which occur following the rapid injection of 5 mg/kg of r595 lps, the infusion o ... | 1978 | 99042 |
| purification and properties of glutamate synthase and glutamate dehydrogenase from bacillus megaterium. | bacillus megaterium n.c.t.c. no. 10342 exhibits glutamate synthetase (ec 2.6.1.53) and glutamate dehydrogenase (ec 1.4.1.4) activities. concentrations of glutamate synthase were high when the bacteria were grown on 3mm-nh4cl and low when they were grown on 100mm-nh4cl, whereas glutamate dehydrogenase concentrations were higher when the bacteria were grown on 100mm-nh4cl than on 3mm-nh4cl. glutamate synthase and glutamate dehydrogenase were purified to homogeneity from b. megaterium grown in 10mm ... | 1978 | 99144 |
| accumulation of thallous ions (tl+) as a measure of the electrical potential difference across the cytoplasmic membrane of bacteria. | the accumulation of thallous ions (204tl+) by intact bacteria was investigated. i conclude that tl+ is a permeant cation, and that it therefore accumulates in response to the electrical potential difference (delta psi) across the cytoplasmic membrane (interior negative). a comparison with other methods shows that the distribution ratio of 204tl+ serves as a reasonably satisfactory method for measuring the membrane potential of streptococcus faecalis. glycolyzing cells of this organism develop me ... | 1978 | 99163 |
| metabolic control of lactose entry in escherichia coli. | a general method has been developed for determining the rate of entry of lactose into cells of escherichia coli that contain beta-galactosidase. lactose entry is measured by either the glucose or galactose released after lactose hydrolysis. since lactose is hydrolyzed by beta-galactosidase as soon as it enters the cell, this assay measures the activity of the lactose transport system with respect to the translocation step. using assays of glucose release, lactose entry was studied in strain gn2, ... | 1978 | 99173 |
| formation of spirodilactone of 4-(2'-carboxyphenyl)-4,4-dihydroxybutyrate from 2-succinylbenzoate in cell-free extracts of micrococcus luteus. | the enzyme mediated atp- and, to a lesser extent, coash-dependent synthesis of the spirodilactone of 4-(2'-carboxyphenyl)-4,4-dihydroxybutyrate from 2-succinylbenzoate has been demonstrated in membrane-free extracts of micrococcus luteus and escherichia coli. the suggestion is made that the spirodilactone is the product of an aberrant reaction involving a compound that is normally an intermediate in the conversion of 2-succinylbenzoate to 1,4-dihydroxy-2-naphthoate. | 1978 | 99177 |
| [the activation of membrane bound adenylate cyclases by culture filtrates of certain escherichia coli strains]. | | 1978 | 99264 |
| improved enzymatic assay of chloramphenicol. | we partly purified r-factor-encoded chloramphenicol acetyltransferase (ec 2.3.1.28) from a highly choloramphenicol-resistant mutant derived from escherichia coli w677/r5. the preparation permitted rapid quanitation of chloramphenicol by use of [14c]acetylcoenzyme a, removing the diacetylated product by selective adsorption onto micropore filters. succinyl and glucuronyl 3-hydroxyl esters of chloramphenicol were not active as substrates for the preparation, nor were they active as inhibitors. the ... | 1978 | 99271 |
| double-antibody enzyme immunoassay for nortriptyline. | beta-d-galactosidase (ec 3.2.1.23) from escherichia coli was conjugated to desmethylnortriptyline by means of a bifunctional cross-linking reagent, dimethyl adipimidate, and used in a double-antibody immunoassay for nortriptyline. eighty percent of the enzyme activity was retained after conjugation; 75% of the enzyme was conjugated to desmethylnortriptyline. in the final immunoassay the enzyme activity of the bound fraction was determined with o-nitrophenyl-beta-d-galactopyranoside as substrate. ... | 1978 | 99272 |
| in vivo titration of arac protein. | the requirement for arac protein in the induction of the arabad operon was investigated. strains of escherichia coli carrying an arac(am) mutation and temperature-sensitive amber suppressors were used to vary the intracellular level of arac protein. the levels of arac protein studied ranged from 0.007 to 1.8 times the normal amount. the results indicate that the normal level of arac protein is just sufficient to provide maximal expression of the arabad operon. | 1978 | 99435 |
| transport by the lactose permease of escherichia coli as the basis of lactose killing. | lactose killing is a peculiar phenomenon in which 80 to 98% of the escherichia coli cells taken from a lactose-limited chemostat die when plated on standard lactose minimal media. this unique form of suicide is caused by the action of the lactose permease. since uptake of either lactose or galactose by the lactose permease caused death, the action of rapid transport across the membrane must be the cause of the phenomenon. alternative causes of lactose killing, such as accumulation of toxic metab ... | 1978 | 99437 |
| separation and characterization of the outer membrane of pseudomonas aeruginosa. | a method is described for the preparation of outer and cytoplasmic membranes of pseudomonas aeruginosa, and the outer membrane proteins characterized. isolated outer and cytoplasmic membranes differed markedly in the content of 2-keto-3-deoxyoctonate (lipopolysaccharide) and phospholipid as well as in the localization of certain enzymes (nadh oxidase, succinate dehydrogenase, d-lactate dehydrogenase, malate dehydrogenase, and phospholipase), and also in the microscopic morphology. the outer memb ... | 1978 | 99443 |