bluuebunny/crossref_metadata_2025 huggingface dataset:
Single-stranded regions in Streptococcus pneumoniae chromosomal deoxyribonucleic acid and their relation to transformation
Authors: Deddish P A , Ravin A W
Published: January 2020

Deoxyribonucleic acid (DNA) in lysates of both completent and noncompetent streptococcus pneumoniae cells was characterized by chromatography on benzoylated, naphthoylated diethylaminoethyl-cellulose columns, by sensitivity to Aspergillus oryzae S1 endonuclease, and by sucrose gradient analysis. The DNAs from both competent and noncompetent cells were found to contain similar extents of single-stranded regions. These single-stranded regions appeared to be intact, unpaired regions in double-stranded DNA rather than gaps, nicks, or unpaired ends in the DNA. Inhibition of cells with rifampin prior to lysis increased the amount of such single strandedness in the DNA. Lysates made at various times after [14C]thymidine-labeled cells had bound [3H]thymidine-labeled transforming DNA were also characterized by benzoylated, naphthoylated diethylaminoethyl-cellulose chromatography. Changes in the elution profiles of DNA from cells exposed to homospecific (S. pneumoniae) donor DNA were indicative of the formation of complexes between donor DNA and the single-stranded regions of recipient DNA. In contrast, profiles of DNA from cells exposed to heterospecific (S. sanguis) DNA did not show significant changes, indicating that few such donor-recipient complexes were formed during heterospecific transformation.
Positive selection of mutants with cell envelope defects of a Salmonells typhimurium strain hypersensitive to the products of genes hisF and hisH
Authors: Antón D N
Published: January 2020

Strain SB564 and its derivative DA78 are hypersensitive to the inhibitory action of the proteins coded for by genes hisF and hisH on cell division. Transduction of hisO1243, a regulatory mutation that elicits a very high level of expression of the histidine operon, into these strains resulted in the production of long filamentous cells carrying large "balloons" and in growth failure. Forty-one hisO1242 derivatives that escaped inhibition were isolated. These strains showed a large variety of alterations, many of which were related to the cell envelope. The more-frequent alterations included: changes in cell shape, increased sensitivity to one or more of several drugs (deoxycholate, cycloserine, penicillin, novobiocin, acridine orange), increased autolytic activity in alkaline buffer, anomalous fermentation of maltose on eosin--methylene blue plates, and temperature-conditional cell division. The alterations are produced, in some of the strains, by pleiotropic mutations in gene envB (Antón, Mol, Gen. Genet. 160:277--286, 1978) or envD (Antón and Orce, Mol. Gen. Genet. 144:97--105, 1976). Strains affected in divC, divD, and rodA loci have also been identified. Genetic analysis has shown that several strains carry more than one envelope mutation. It is assumed that envelope mutations are positively selected because they somehow alleviate the particularly severe inhibition of cell division caused, in strains SB564 and DA78, by the excessive synthesis of hisF and hisH gene products.
NgoII, a restriction endonuclease from Neisseria gonorrhoeae
Authors: Clanton D J , Riggsby W S , Miller R V
Published: January 2020

EndoR . NgoII, a class II restriction endonuclease isolated from Neisseria gonorrhoeae, was purified to electrophoretic homogeneity. We were able to separate it from another restriction endonuclease of N. gonorrhoeae, NgoI, by phosphocellulose chromatography. NgoII is an isoschizomer of HaeIII, a restriction endonuclease of Haemophilus aegyptius, and was found to recognize the deoxyribonucleic acid nucleotide base sequence GGCC. NgoII was able to digest phage lambda deoxyribonucleic acid over a wide pH range, with optimal activity at pH 8.5. The enzyme has an absolute requirement for Mg2+; maximal enzyme activity was observed at 1 mM Mg2+. The active enzyme has a molecular weight of 65,000 and appears to be composed of six subunits of identical molecular weight (11,000). No methylase activity could be detected in the purified enzyme preparation.
Axial filament involvement in the motility of Leptospira interrogans
Authors: Bromley D B , Charon N W
Published: January 2020

Motility mutants of Leptospira interrogans serovar illini were isolated and analyzed by dark-field and electron microscopy. Mutants were obtained by screening for small colonies after nitrosoguanidine treatment. One class of mutants did not have hook- or spiral-shaped ends. In addition, the axial filaments from these mutants were not coiled. An analysis of revertants of two of the mutants in this class indicated that the mutations were pleiotropic with respect to motility, hook- and spiral-shaped ends, and axial filament coiling. We conclude that the axial filaments and the hook- and spiral-shaped ends are involved in L. interrogans motility.
Helix handedness of Leptospira interrogans as determined by scanning electron microscopy
Authors: Carleton O , Charon N W , Allender P , O'Brien S
Published: January 2020

Representative serovars and strains of the seven genetic groups of Leptospira interrogans, and two previously studied serovars, were all found to form exclusively right-handed helices as determined by scanning electron microscopy. No change in handedness occurred in cells grown in a minimal medium (Tween-80 albumin) compared to cells grown in a rich medium (rabbit serum). The right-handedness of the organisms was related to the evolution, cell wall structure, and the mechanism of motility of L. interrogans.
Screening for amino acid pool mutants of Neurospora and yeasts: replica-printing technique
Authors: Cramer C L , Davis R H
Published: January 2020

A replica-printing technique has been developed for permeabilized colonies of Neurospora and yeast by which endogenous amino acid pools are visualized. By the use of cation-exchange paper, the method has detected Neurospora mutants unable to store the large pools of basic amino acids characteristic of wild type. Mutants of this sort were sought to study the function of the fungal vacuole.
Enhancement of deoxyribonucleic acid polymerase I-directed repair synthesis in toluene-treated Escherichia coli after growth in the presence of low levels of N-methyl-N'-nitro-N-nitrosoguanidine
Authors: Billen D , Hellermann G R
Published: January 2020

Deoxyribonucleic acid polymerase I-directed repair synthesis can be selectively measured in toluene-treated Escherichia coli cells exposed to alkylating chemicals such as N-methyl-N'-nitro-N-nitrosoguanidine. Prior growth of the cells in the presence of a low dose of N-methyl-N'-nitro-N-nitrosoguanidine results in an enhanced deoxyribonucleic acid polymerase I-directed repair synthesis and an increase in single-strand breaks.
Suppression of polar effects of nonsense mutations by ultraviolet irradiation
Authors: Pollock T J , Tessman E S , Tessman I
Published: January 2020

Nonsense mutations in capsid genes F and G of phages S13 and phi X174 decreased the expression of genes downstream. These polar effects were suppressed by ultraviolet irradiation of the host before infection. Activities of the downstream genes were restored to between 30 and 95% of their normal levels, as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis of the viral proteins. The effect of ultraviolet irradiation may be to suppress rhodependent termination of transcription. The polarity of one mutation was poorly suppressed by ultraviolet irradiation.
Superoxide dismutase and O2 lethality in Bacteroides fragilis
Authors: Privalle C T , Gregory E M
Published: January 2020

Exposure of midlog Bacteroides fragils (VPI 2393) to 2% O2-98% N2 caused a three- to fivefold increase in superoxide dismutase specific activity within the cells. The increase in specific activity was completed within 90 min after exposure to oxygen and was dependent upon protein synthesis. Cells containing the higher superoxide dismutase level were more resistant to the effects of 5 atm of oxygen tension than were cells containing the lower level of superoxide dismutase but were equally resistant to 5 atm of nitrogen tension. Similar results were observed upon comparing viability experiments with B. fragilis and B. vulgatus. Superoxide dismutase activity in sonic extracts of B. fragilis was rapidly inactivated by exposure to 5 mM H2O2 and was inhibited by 1 mM NaN3 but not 5 mM NaCN. The inhibition pattern is identical to the pattern demonstrated for the purified iron-containing enzyme from Escherichia coli B and suggests that the superoxide dismutase in B. fragilis is an iron enzyme.
Influence of Iron on Yields of Extracellular Products in
Pseudomonas aeruginosa
Cultures
Authors: Bjorn Michael J. , Sokol Pamela A. , Iglewski Barbara H.
Published: January 2020

The effect of the iron content of the medium on the yields of extracellular products by seven distinct strains of
Pseudomonas aeruginosa
was examined. All strains showed at least an 85% decrease in toxin A yields when grown in medium containing 5.0 μg of iron per ml (high iron) as compared to 0.05 μg/ml (low iron), whereas bacterial growth increased approximately twofold. During the course of examining extracellular products produced by
P. aeruginosa
, we found many strains that produced an extracellular factor which agglutinated erythrocytes. This hemagglutinin was nondialyzable, heat stable, and resistant to Pronase and trypsin. The effect of iron on extracellular yields of hemagglutinin was strain dependent; four of seven strains showed decreases in hemagglutinin yields in high-iron medium. Similarly, the effect of increasing the iron concentration of the growth medium on yields of total extracellular proteases or on elastase was strain dependent. The amount of total extracellular protein was decreased by at least 31% in the high-iron medium for all strains of
P. aeruginosa
examined. Detailed studies on one strain (WR-9) showed that, in the presence of increasing amounts of iron in the medium, the extracellular yields of toxin A, protease, and hemagglutinin were decreased in a similar manner. In addition, the kinetics of release of these extracellular products were similar at a given iron concentration. Thus it appears that the yields of other extracellular products of
P. aeruginosa
besides toxin A are influenced by the concentration of iron in the growth medium.
Characterization of arithmetic deoxyribonucleic acid synthesis at restrictive temperature in a dnaE mutant of Escherichia coli K-12
Authors: Wechsler J A , Kurtz W H
Published: January 2020

The dna-293 mutation is shown to be a dnaE allele. The linear deoxyribonucleic acid synthesis previously observed in this mutant has been further characterized. The production of small deoxyribonucleic acid intermediates and their subsequent joining were identical in the mutant and its dnaE+ parent at 42.5 degrees C. Though the mutant cells continued to divide at the nonpermissive temperature, the rate of division was reduced. The data are consistent with a lack of production of replicationally active deoxyribonucleic acid polymerase III at the restrictive temperature.
Resolution of glpA and glpT loci into separate operons in Escherichia coli K-12 strains
Authors: Miki K , Silhavy T J , Andrews K J
Published: January 2020

The independent insertion of bacteriophage Mu into the gene coding for anaerobic sn-glycerol 3-phosphate dehydrogenase (glpA) or into the genes coding for sn-glycerol 3-phosphate transport (glpT) suggested that these two closely linked loci are in separate operons.
Polypeptides expressed in Escherichia coli K-12 minicells by transposition elements Tn1 and Tn3
Authors: Dougan G , Saul M , Twigg A , Gill R , Sherratt D
Published: January 2020

Escherichia coli K-12 minicells were employed to examine polypeptides encoded by plasmids carrying wild-type and mutant Tn1 or Tn3 transposition elements. Tn1- and Tn3-containing minicells express high levels of four transposon-specified polypeptides. Three, of molecular weights 30,000, 28,000, and 25,000, are related immunologically to beta-lactamase, the enzyme responsible for ampicillin hydrolysis. A fourth polypeptide of molecular weight 19,000 is encoded by the Tn1 or Tn3 region which spans the BamHI cleavage site. Mutant transposons which no longer produce this polypeptide transpose at higher than wild-type frequencies to give aberrant transposition products (Gill et al., J. Bacteriol. 136: 742--756, 1978; Heffron et al., Proc. Natl. Acad. Sci U.S.A. 72:3632--3627, 1975). No expression could be detected from a region of the transposons extending from the inverted repeat sequence distal to the beta-lactamase gene to more than half the distance into the Tn1 or Tn3 sequence.
Genetic mapping of the chromosomal replication origin of Salmonella typhimurium
Authors: Joh K , Hiraga S
Published: January 2020

Two hundred strains of Escherichia coli harboring Filv+ plasmids which carry a segment of the Salmonella typhimurium chromosome were isolated independently. Among them, two strains were found to harbor F' plasmids that are able to replicate in Hfr cells of E. coli; i.e., they carry a site designated poh (permissive on Hfr) of the S. typhimurium chromosome. The poh site is presumably identical with the replication origin (oriC) of the bacterial chromosome. These two plasmids carry the dnaA-uncA-rbs-ilv-cya-metE region of the chromosome of S. typhimurium. Other F' plasmids which only carried the ilv-cya-metE region were unable to be maintained in Hfr cells. The poh site (= oriC) of S. typhimurium thus is located in the uhp-ilv region of the chromosome. The two plasmids carrying the poh site of S. typhimurium can suppress the temperature-sensitive character of an E. coli mutant that carries the temperature-sensitive dnaA46 allele, when the plasmids exist in the mutant cells. This suggests that the dnaA chromosome in place of the dnaA gene product of E. coli itself. The ability of the plasmids carrying the poh site of S. typhimurium to replicate in Hfr cells of E. coli suggests that the replication system of E. coli can recognize the Salmonella replication origin.
Genetic studies of an Escherichia coli K-12 temperature-sensitive mutant defective in membrane protein synthesis
Authors: Sato T , Ohki M , Yura T , Ito K
Published: January 2020

The mutant divE42(Ts) of Escherichia coli K-12, defective in the synthesis of membrane proteins and in the transcription of the lac operon at high temperature, has been further characterized. It was found that a mutation (divE42) located at about min 22 on the E. coli chromosome map is responsible for the Lac- phenotype and temperature-sensitive growth. The mutation could be contransduced with serC, pyrD, or pyrC by phage P1 at a frequency of 4, 16, or 0.5%, respectively, the gene order being serC-pyrD-ompA-sulA-divE-pyrC. Examination of temperature-independent revertants and Pyr+ transductants revealed that all the mutant phenotypes examined (deficiencies in the increase of activities of some membrane enzymes, expression of the lac operon, and synthesis of several other proteins) are due to a single mutation (divE42) which is recessive to the wild-type (divE+) allele. Protein synthesis in the mutant was also analyzed by dodecyl sulfate-polyacrylamide gel electrophoresis. Synthesis of a number of proteins, including membrane proteins, was found to decrease significantly, whereas that of an elongation factor, EF-Tu, increased upon transfer of a log-phase culture to high temperature (42 degrees C). These effects of temperature shift-up on protein synthesis were evident within 5 min under the conditions used.
Multiple loci affecting photoreactivation in Escherichia coli
Authors: Sutherland B M , Hausrath S G
Published: January 2020

Sutherland et al. mapped a phr gene in Escherichia coli at 17 min and found that induction of an E. coli strain lysogenic for a lambda phage carrying this gene increased photoreactivating enzyme levels 2,000-fold. Recently, Smith and Youngs and Sancar and Rupert located a phr gene at 15.9 min. We have therefore investigated the properties of photoreactivating enzyme and cellular photoreactivation in cells containing deletions of the gene at 17 min. Cells with this deletion photoreactivated ultraviolet-induced killing at a rate 20% of normal; they also contained approximately 20% of the normal photoreactivating enzyme level. The residual enzyme in these cells was characterized to determine whether the reduced cellular photoreactivation rate and photoreactivating enzyme levels resulted from reduced numbers of normal enzymes or from an altered enzyme. Photoreactivating enzymes from strains carrying a deletion of the region at 17 min had an apparent Km about two- to threefold higher than normal enzyme and showed markedly increased heat lability. The gene at 17 min thus contains information determining the function of the E. coli photoreactivating enzyme rather than the quantity of the enzyme. It is proposed that the gene at 17 min be termed phrA and that located at 15.9 min be termed phrB.
Isolation and characterization of a temperature-sensitive dnaK mutant of Escherichia coli B
Authors: Itikawa H , Ryu J
Published: January 2020

A temperature-sensitive dnaK mutant (strain MT112) was isolated from Escherichia coli B strain H/r30RT by thymineless death selection at 43 degrees C. By genetic mapping, the mutation [dnaK7(Ts)] was located near the thr gene (approximately 0.2 min on the may). E. coli K-12 transductants of the mutation to temperature sensitivity were assayed for their susceptibility to transducing phage lambda carrying the dnaK and/or the dnaJ gene. All of the transductants were able to propagate phage lambda carrying the dnaK gene. When macromolecular synthesis of the mutant was assayed at 43 degrees C, it was observed that both deoxyribonucleic acid and ribonucleic acid syntheses were severely inhibited. Thus, it was suggested that the conditionally defective dnaK mutation affects both cellular deoxyribonucleic acid and ribonucleic acid syntheses at the nonpermissive temperature in addition to inability to propagate phage lambda at permissive temperature.
Escherichia coli mutant containing a large deletion from relA to argA
Authors: Atherly A G
Published: January 2020

A mutant of Escherichia coli has been isolated that contains a large deletion (about 3 X 10(7) daltons of deoxyribonucleic acid) encompassing argA, fuc, and relA. This mutant strain (AA-787) is also cold sensitive for growth at 18 degrees C. Strain AA-787 was obtained fortuitously as a cold-sensitive pseudorevertant of a strain having a heat-sensitive peptidyl-transfer ribonucleic acid hydrolase. Genetic analysis, using transduction and interrupted mating, showed the cold sensitivity mutation to be located adjacent to relA. Further analysis demonstrated loss of relA, fuc, and argA gene functions but retention of eno and recB, closely linked genes adjacent to relA and argA, respectively. Unusually high cotransduction of flanking markers (cysC and thyA) indicated loss of approximately 1 min of the E. coli genetic map in strain AA-787. Guanosine 3'-diphosphate 5'-diphosphate (ppGpp) was synthetized in mutant strain AA-787 at basal levels, and ppGpp synthesis was stimulated by carbon-source downshift. No ppGpp synthesis could be obtained using ribosomes isolated from strain AA-787. These findings, taken together, show that deletion of relA in E. coli does not completely abolish ppGpp synthesis and suggests that another enzyme system must also be responsible for ppGpp synthesis.
Deletion mapping of the polA-metB region of the Escherichia coli chromosome
Authors: Pahel G , Bloom F R , Tyler B
Published: January 2020

A lambdacI857 prophage inserted into one of the genes of the rha locus was used to select deletions unambiguously ordering the markers polA-glnA-rha-pfkA-tpi-metBJF. Transduction with phage P1 indicates at least 70% linkage between glnA and polA. The order of the pfk and tpi markers is reversed from that previously published. Despite the relatively large distance separating the glnA and rha loci, deletions removing this entire region have no obvious phenotype. The isolation of Tn10 transposons integrated at different sites between rha and glnA greatly facilitated this work.
Nature of transforming deoxyribonucleic acid in calcium-treated Escherichia coli
Authors: Strike P , Humphreys G O , Roberts R J
Published: January 2020

A study of the reactivation of ultraviolet-irradiated plasmid and phage deoxyribonucleic acid molecules after transformation into Escherichia coli strains indicated that, when double-stranded deoxyribonucleic acid was used as the donor species, it was taken up without conversion to the single-standed form.
Aflatoxin biosynthesis: detection of transient, acetate-dependent intermediates in Aspergillus by kinetic pulse-labeling
Authors: Zamir L O , Ginsburg R
Published: January 2020

A simple technique was developed for the detection of intermediary metabolites of Aspergillus versicolor that are putative precursors of aflatoxin. Minicolony populations were allowed to metabolize [1,2-14C]acetate over various time intervals. The biosynthetic reactions were quenched by quick-freezing the minicolonies, the cells were disrupted, and the metabolites were extracted into acetone. Small silica thin-layer chromatographic plates were then used to separate any radioactive metabolites present. Elution in two or three different directions was often necessary. Radioautography of the thin-layer chromatography plates provided a sensitive assay for the appearance of the various intermediates in a timing pattern which implicated the sequence of formation. Transient intermediates were distinguished from dead-end metabolites by the rapid formation and disappearance of the former. At least five unknown precursors of versicolorin A, a dead-end metabolite, were recognized. The kinetic pulse-labeling technique should be generally applicable to other fungal species whenever the entrapment of intermediary metabolites in the mycelium poses and technical problem.
Lactose metabolism involving phospho-beta-galactosidase in Klebsiella
Authors: Hall B G
Published: January 2020

Klebsiella strain RE1755A is a Lac- Gal- mutant which has lost both of its lac operons, but possesses a gene specifying beta-galactosidase III, an enzyme which hydrolyzes o-nitrophenyl-beta-D-galactopyranoside but does not hydrolyze lactose. Selective pressure was applied to isolate mutants able to utilize lactose. The lactose-utilizing mutants obtained were shown to possess an unaltered beta-galactosidase III. Lactose utilization was shown to result from a pleiotropic mutation which also (i) permits galactose utilization and (ii) prevents induction of beta-galactosidase III synthesis by lactose. Evidence is presented suggesting that a phospho-beta-galactosidase enzyme is involved in lactose metabolism.
Apparent involvement of purines in the control of expression of Salmonella typhimurium pyr genes: analysis of a leaky guaB mutant resistant to pyrimidine analogs
Authors: Jensen K F
Published: January 2020

A leaky guaB mutant of Salmonella typhimurium LT-2 was obtained during a selection for mutants resistant to a combination of the two pyrimidine analogs, 5-fluorouracil and 5-fluorouridine. In the absence of exogenous guanine compounds, the growth rate of this mutant is limited by the endogenous supply of guanine nucleotides due to a defective inosine 5'-monophosphate dehydrogenase. Under these conditions the guanosine 5'-triphosphate pool is about 20% of normal, the cytidine 5'-triphosphate pool is reduced to below 60%, and the uridine 5'-triphosphate pool is slightly elevated. Simultaneously, levels of the pyrimidine biosynthetic enzymes are abnormal: aspartate transcarbamylase, orotate phosphoribosyltransferase, and orotidylic acid decarboxylase levels are increased 4-, 11-, and 3-fold, respectively. Levels of dihydroorotase and dihydroorotate dehydrogenase are decreased to 10 and 20%, respectively. The pyrimidine metabolism of the guaB mutant is restored completely by addition of guanine (or xanthine) to the growth medium. The data indicate purine nucleotide involvement in the regulation of expression of the pyr genes of S. typhimurium.
Genetic exchange mechanisms in Neisseria gonorrhoeae
Authors: Norlander L , Davies J , Normark S
Published: January 2020

There are two mechanisms for genetic exchange in Neisseria gonorrhoeae. Plasmid deoxyribonucleic acid can be transferred by conjugation, which is dependent on the presence of a 24.5-megadalton plasmid in the donor cell. We have shown that chromosomal deoxyribonucleic acid can be exchanged between all colonial variants by transformation, but not by conjugation. In the nonpiliated variants, however, this exchange was dependent on the presence of the 24.5-megadalton plasmid in the recipient cell.
Genes coding for ribosomal proteins S15, L21, and L27 map near argG in Escherichia coli
Authors: Kitakawa M , Dabbs E R , Isono K
Published: January 2020

Mutants with alterations in the structural genes for ribosomal proteins S15, L21, and L27 were used in mapping the genes coding for these proteins. Results from P1kc-mediated transductions indicate that the genes for L21 (rplU) and L27 (rpmA) form a gene cluster and are located between argG and gltB at 68.1 min, whereas the gene for S15 (rpsO) is situated close to, but on the opposite side or, argG. The gene order in this region is concluded to be gltB-(rplU, rpmA)-argG-rpsO-mtr.
Transient growth inhibition of Escherichia coli K-12 by ion chelators: "in vivo" inhibition of ribonucleic acid synthesis
Authors: Collins J J , Alder C R , Fernandez-Pol J A , Court D , Johnson G S
Published: January 2020

The ion chelators picolinic acid, quinaldic acid, 1,10-phenanthroline, and 8-hydroxyquinoline, but not ethylenediaminetetraacetate, ethyleneglycol-bis-(beta-aminoethyl ether)-N,N-tetraacetate, or dipicolinic acid, rapidly but transiently arrest growth of Escherichia coli K-12. Cells adapt and become resistant to growth inhibition by these agents, a process which requires protein synthesis. Mn2+, at low concentrations, decreases the time required for resumption of growth. Proteins synthesized during the lag are quantitatively and qualitatively different from those synthesized during normal growth. Inhibition of growth can explained by an effect on RNA polymerase, a known metalloenzyme.
Effect of alanine-containing dipeptides on germination of Bacillus thiaminolyticus spores
Authors: Watabe K , Sano K , Otani M , Okada Y , Kakiuchi Y , Kondo M
Published: January 2020

Stereoisomeric alanylalanine (Ala-Ala) derivatives were examined for their effects on germination of Bacillus thiaminolyticus spores. L-Ala-L-Ala and L-Ala-glycine were effective in inducing germination, and their activities were completely inhibited by D-Ala. L-Ala-D-Ala and glycine-D-Ala competitively prevented L-Ala-induced germination. Sarcosine- or beta-Ala-containing L-alanyldipeptides and eight kinds of alanyltripeptides did not show any detectable effect on germinability or any inhibitory effect. No detectable amounts of Ala were found in germination exudates when alanylpeptides were incubated with spores. The ability of these peptides to induce or inhibit germination depends on their steric conformation and a certain distance between the primary amino group and the free carboxyl groups. Involvement of L-Ala dehydrogenase in the initiation of germination is unlikely because L-Ala-L-Ala was not a substrate and L-Ala-D-Ala was not an effective inhibitor of enzyme activity.
Expression of the cloned uvrB gene of Escherichia coli: mode of transcription and orientation
Authors: Pannekoek H , Noordermeer I , van de Putte P
Published: January 2020

The Escherichia coli uvrB gene, located on a 1.5-megadalton EcoRI (fragment F, derived from transducing phage lambda b2att2 [lambda b2cI857intam6 delta (bioAB)bio-FCD+uvrB+], has been cloned in the unique EcoRI site of several "relaxed" plasmids, i.e., pMB9, pBR322, and pBH20 (= ;BR322, including the lac regulatory elements [K. Itakura, T. Hirose, R. Crea, A. D. Riggs, H. L. Heyneker, F. Bolivar, and H. W. Boyer, Science 198:1056--1063, 1977]y. Expression of the uvrB gene, both on pMB9 and on pBH20, occurs only when fragment F has one particular orientation. Cloning of this fragment on pBR322 in either orientation does not allow expression of the uvrB gene. Transcription of this gene on pNP5 ( = pMB9 uvrB) is shown to be dependent on a pMB9 promotor that is located on a 0.22-megadalton EcoRI-HindIII fragment. Using plasmid pBH20 as a vector, we could demonstrate that expression of the uvrB gene is under control of the lac promotor-operator region. From deoxyribonucleic acid-deoxyribonucleic acid hybridization experiments with lambda pgal8 deoxyribonucleic acid and restriction fragments of pNP5 deoxyribonucleic acid it could be shown that the uvrB gene is transcribed clockwise on the chromosome.
Lipid and lipopolysaccharide composition of Acholeplasma oculi
Authors: Al-Shammari A J , Smith P F
Published: January 2020

The total lipid content of Acholeplasma oculi comprises 13.3% of the dry weight of the organism and is about equally distributed between the neutral lipids plus glycolipids and the phospholipids. The phospholipids were identified as phosphatidyl glycerol and diphosphatidyl glycerol. The glycolipid fraction contained O-alpha-D-glucopyranosyl-(1 leads to 1)-2,3-diacyl glycerol and O-alpha-D-glucopyranosyl-(1 leads to 2)-O-alpha-D-glucopyranosyl-(1 leads to 1)-2,3-diacyl glycerol. The neutral lipid contained pigmented carotenoids. Hot aqueous phenol extraction of lipid-extracted whole cells yielded a polymeric carbohydrate comprising 2.3% of the dry weight of the organism. The A. oculi lipopolysaccharide was found to contain only neutral sugars and no amino sugar, in contrast to other acholeplasmas. The neutral sugars consisted of fucose, galactose, and glucose in a ratio of 2:19:3.
Specific inactivator of flagellar reversal in Salmonella typhimurium
Authors: Spudich J L , Koshland D E
Published: January 2020

Specific inhibition of flagellar rotation reversal was observed after exposure of chemotactic Salmonella typhimurium to citrate autoclaved at neutral pH. The presence of a rotation reversal inactivator was established in autoclaved citrate-containing media and nutrient broth. Since modulation of flagellar rotation by attractants and repellents is the basis of chemotactic behavior, a specific inhibitor of rotation reversal, which is essential for tumble generation, provides a useful probe into the molecular mechanism of bacterial chemotaxis. The inactivator inhibits clockwise rotation without affecting counterclockwise rotation, speed of rotation, or the capacity of the cells to grow and divide. Inactivation of clockwise rotation is gradual and irreversible, differing from the transient inhibition of clockwise rotation by attractants, which is characterized by an immediate suppression followed by a return to normal rotation patterns. The rotation reversal inactivator is stable to acidification, rotary evaporation, lyophilization, and rehydration.
Plasmid transfer in Haemophilus influenzae
Authors: Stuy J H
Published: January 2020

Twenty-nine strains of Haemophilus influenzae highly resistant to ampicillin, chloramphenicol, or tetracycline were examined for the presence of plasmids. Agarose gel electrophoresis of ethanol-precipitated cell extracts revealed large plasmids in 11 strains, of which 7 were conjugative. Plasmid transfer by conjugation between isogenic strains was quite efficient, but transfer between different serotypes was nearly always much more inefficient. Type I or II restriction enzymes do not appear to be barriers to this transfer. Encapsulated cells can be both efficient donors and recipients. Small plasmids were seen in three strains, but only two of the three are resistance factors (RSF0885, pUB703). Thus, in 17 isolates antibiotic resistance genes are believed to be located in the bacterial chromosome. Most of these resistances could be transferred by genetic transformation into the widely used Rd strain. In some cases transfer of chromosomal resistance into conjugative plasmids was observed in both rec+ and rec host cells. Since transfer by conjugation seems to be the more efficient process, it is puzzling that in the majority of the 29 isolates studied resistance genes appeared to be in the chromosome.
Isolation and characterization of replication-deficient mutants of ColE1 plasmids
Authors: Hashimoto-Gotoh T , Inselburg J
Published: January 2020

Replication-defective mutants of plasmid ColE1 were isolated from a chimeric plasmid formed by ligating a temperature-sensitive replication derivative of pSC101, pHSG1, with a ColE1-Tn3-containing plasmid. The replication-defective ColE1 mutants isolated were all spontaneous deletion mutants that had lost the ColE1 replication origin and regions adjacent to it. The extent of a deletion was determined by analyzing restriction endonuclease-generated deoxyribonucleic acid fragments of the ColE1 plasmid component of the chimeras by both agarose and polyacrylamide gel electrophoresis. None of the chimeras containing the replication-defective ColE1 mutants was able to replicate in the presence of chloramphenicol. The expression of ColE1 incompatibility was either markedly reduced or not detectable in the replication mutants isolated.
Pleiotropic effects of ribosomal mutations for cycloheximide resistance in a double-resistant homocaryon of Neurospora crassa
Authors: Vomvoyanni V E , Argyrakis M P
Published: January 2020

Pleiotropic effects of two ribosomal mutations for cycloheximide resistance were studied in a double-resistant homocaryon. The results obtained indicated that the combination of the two ribosomal mutations results in: (i) morphological abnormalities which suggest a severe distortion in the extension of cell walls and membranes; (ii) disturbance in the normal 60S-40S subunit ratio; (iii) decreased rate of cell mass production not necessarily associated with inbalance in the 60S-40S ratio; and (iv) cold sensitivity which does not interfere with mycelial mass production.
Increased synthesis of ribonucleotide reductase after deoxyribonucleic acid inhibition in various species of bacteria
Authors: Filpula D , Fuchs J A
Published: January 2020

The specific activity of ribonucleotide reductase was found to increase significantly after deoxyribonucleic acid inhibition in seven species of bacteria investigated. This group of bacteria includes species with B12-dependent ribonucleotide reductase as well as some with an Escherichia coli-type ribonucleotide reductase.
Glutamine as a feedback inhibitor of the Rhodopseudomonas sphaeroides nitrogenase system
Authors: Jones B L , Monty K J
Published: January 2020

In whole cells of Rhodopseudomonas sphaeroides, nitrogen fixation, as measured by hydrogen production and acetylene reduction, was totally inhibited by micromolar concentrations of ammonia. This inhibition could not be duplicated by glutamate or glutamine alone. The inhibition by ammonia was abolished by methionine sulfoximine, a glutamine synthetase inhibitor. Inhibition by glutamine was complete in the presence of methionine sulfone, a preferential inhibitor of glutamate synthase, presumably by permitting a rise in the glutamine pool. The results indicated that the level of the glutamine pool controlled the activity of nitrogenase. None of these effects could be duplicated with cell-free nitrogenase, indicating there is probably a mediator which responds to the glutamine pool and inhibits nitrogenase, rather than glutamine itself being a direct inhibitor.
Alterations in peptidoglycan chemical composition associated with rod-to-sphere transition in a conditional mutant of Klebsiella pneumoniae
Authors: Fontana R , Canepari P , Satta G
Published: January 2020

Klebsiella pneumoniae Mir M7 is a spontaneous parentless morphology mutant which grows as cocci at pH 7 and as rods at pH 5.8. This strain has been characterized as defective in lateral wall formation (at pH7). Data suggest that the cell wall is mainly made up of poles of the rods (G. Satta, R. Fontana, P. Canepari, and G. Botta, J. Bacteriol. 137:727--734, 1979). In this work the isolation and the biochemical properties of the peptidoglycan of both Mir M7 rods and cocci and a nonconditional rod-shaped Mir M7 revertant (strain Mir A12) are described. The peptidoglycan of Mir M7 (both rods and cocci) and Mir A12 strains carried covalently bound proteins which could be easily removed by pronase treatment in Mir M7 rods and Mir A12 cells, but not in Mir M7 round cells. However, when the sodium dodecyl sulfate-insoluble residues of Mir M7 cocci were pretreated with ethylenediaminetetraacetic acid (EDTA), pronase digestion removed the covalently bound proteins, and pure peptidoglycan was obtained. EDTA treatment of the rigid layer of Mir M7 cocci removed amounts of Mg2+ and Ca2+, which were 10- and 50-fold higher, respectively, than the amount liberated from the rigid layer of Mir M7 rods and Mir A12 cells. Amino acid composition was qualitatively similar in both strains, but Mir M7 cocci contained a higher amount of alanine and glucosamine. Mir M7 cocci contained approximately 50% less peptidoglycan than rods. Under electron microscopy, the rigid layer of the Mir M7 rods and Mir A12 cells appeared to be rod-shaped and their shape remained unchanged after EDTA and pronase treatment. On the contrary, the Mir M7 cocci rigid layer appeared to be round, and after EDTA treatment it collapsed and lost any definite morphology. In spite of these alterations, the peptidoglycan of Mir M7 cocci still appeared able to determine the shape of the cell and protect it from osmotic shock and mechanical damages. The accumluation of divalent cations appeared necessary for the peptidoglycan to acquire sufficient rigidity for shape determination and cell protection. We concluded that the coccal shape in Mir M7 cells is not due to loss of cell wall rigidity but is a consequence of the formation of a round peptidoglycan molecule. The possibility that the alterations found in the Mir M7 cocci rigid layer may reflect natural differences in the biochemical composition of the septa and lateral wall of normally shaped bacteria is discussed.
Transfer of kanamycin resistance mediated by plasmid R68.45 in Paracoccus denitrificans
Authors: Paraskeva C
Published: January 2020

Plasmid R68.45 mediates the transfer of kanamycin resistance from Pseudomonas aeruginosa to Paracoccus denitrificans. Kanamycin resistance could be transferred from one strain of P. denitrificans to another, thus opening up the possibility of using R68.45 as a sex factor in P. denitrificans.
Interaction between mutant alleles of araC of the Escherichia coli B/r L-arabinose operon
Authors: Sheppard D E , Eleuterio M , Falgout B
Published: January 2020

Strains were constructed that contain mutational alterations affecting two distinct functional domains within the araC gene protein. The araCi (catabolite repression insensitivity) and araCh (catabolite repression hypersensitivity) mutations were used to alter the catabolite repression sensitivity domain, and mutation to D-fucose resistance was used to alter the inducer binding domain. araCh, D-fucose-resistant double mutants never exhibited constitutive ara operon expression, whereas all of the araCi, D-fucose-resistant double mutants did exhibit constitutivity. When L-arabinose was used as an inducer, most of the double mutants exhibited the sensitivity to catabolite repression associated with the araCi or araCh mutation. However, when D-fucose was used as an inducer, changes in sensitivity to catabolite repression were observed that were attributed to interactions between the two protein domains. The roles of catabolite activator protein and araC gene protein in the induction of the araBAD operon were discussed.
Crossed immunoelectrophoretic analysis of chromatophore membranes from Rhodopseudomonas sphaeroides
Authors: Collins M L , Mallon D E , Niederman R A
Published: January 2020

Triton extracts of intracytoplasmic photosynthetic membranes (chromatophores) purified from Rhodopseudomonas sphaeroides were subjected to crossed immunoelectrophoresis with antiserum raised in rabbits to purified chromatophores. A total of 31 immunoprecipitates was visualized; 2 of the immunoprecipitates were identified as reduced nicotinamide adenine dinucleotide (EC 1.6.99.3) and L-lactate dehydrogenases by enzyme staining techniques. Reaction with a monospecific antiserum identified the photochemical reaction center. Photopigments were associated with a major precipitate in the pattern which was identified on the basis of immunological identity as light-harvesting bacteriochlorophyll a . protein complex. These results provide the basis for a detailed structural and functional analysis of the chromatophore membrane by crossed immunoelectrophoresis.
Properties of Escherichia coli mutants altered in calcium/proton antiport activity
Authors: Brey R N , Rosen B P
Published: January 2020

Mutants sensitive to growth inhibition by CaCl2 were found to have alterations in calcium uptake in everted membrane vesicles. These mutations map at different loci on the Escherichia coli chromosomes. A mutation at the calA locus results in vesicles which have two- to threefold higher levels of uptake activity than vesicles from wild-type cells. The calA mutation is phenotypically expressed as increased sensitivity to CaCl2 in a strain also harboring a mutation in the corA locus, which is involved in Mg2+ transport. The calA locus maps very close to purA and cycA at about min 97. The calB mutation results both in sensitivity to CaCl2 at pH 5.6 and in vesicles with diminished calcium transport capability. The CalB phenotype is also expressed only in a corA genetic background; the calB locus appears to map very near, yet separately from, the calA locus. When the cor+ allele is present, calA and calB mutations still result in a defect in calcium transport in vesicles. In addition, both calC and calD mutations result in vesicles with impaired calcium transport activity. calC is cotransducible with kdp and nagA, whereas calD is cotransducible with proC.
Cistrons encoding Escherichia coli heat-labile toxin
Authors: Dallas W S , Gill D M , Falkow S
Published: January 2020

The structure and products of the two cistrons encoding the Escherichia coli heat-labile toxin (LT) were studied. The LT deoxyribonucleic acid (DNA) region had been isolated as part of a DNA fragment from the plasmid P307, and this fragment was joined to the cloning vector pBR313. Deletion mutations of various lengths were introduced into the LT DNA region and into the adjacent DNA sequences. Analysis of the deletions indicated that the maximum size of the LT DNA region was 1.2 x 10(6) daltons. Two proteins of 11,500 daltons and 25,500 daltons had been shown to be encoded by the LT DNA region. The functions of these LT gene products were investigated. The 11,500-dalton protein had an adsorption activity for Y-1 adrenal cells, and this protein was shown to form aggregates of four or five monomers. The 25,500-dalton protein was shown to have an adenylate cyclase-activating activity. The two cistrons encoding for each of the LT proteins have been located on a genetic map of the LT DNA region. Both cistrons are probably transcribed from the same promoter.
Insertion element analysis and mapping of the Pseudomonas plasmid alk regulon
Authors: Fennewald M , Benson S , Oppici M , Shapiro J
Published: January 2020

We characterized and mapped new mutations of the alk (alkane utilization) genes found on Pseudomonas plasmids of the Inc P-2 group. These mutations were isolated after (i) nitrosoguanidine mutagenesis, (ii) transposition of the Tn7 trimethoprim and streptomycin resistance determinant, and (iii) reversion of polarity effects of alk::Tn7 insertion mutations. Our results indicate the existence of two alk loci not previously described--alkD, whose product is required for synthesis of membrane alkane-oxidizing activities, and alkE, whose product is required for synthesis of inducible membrane alcohol dehydrogenase activity. Polarity of alk::Tn7 insertion mutations indicates the existence of an alkBAE operon. Mapping of alk loci by transduction in P. aeruginosa shows that there are at least three alk clusters in the CAM-OCT plasmid--alkRD, containing regulatory genes; alkBAE, containing genes for specific biochemical activities; and alkC, containing one or more genes needed for normal synthesis of membrane alcohol dehydrogenase. The alkRD and alkBAE clusters are linked but separated by about 42 kilobases. The alkC cluster is not linked to either of the other two alk regions. Altogether, these results indicate a complex genetic control of the alkane utilization phenotype in P. putida and P. aeruginosa involving at least six separate genes.
Cotransformation of temperature sensitivity and nutritional markers in Neisseria gonorrhoeae
Authors: Steinberg V I , Fenton A C , Baker E H , Goldberg I D
Published: January 2020

Cotransformation remains the only tool for establishing linkage in Neisseria gonorrhoeae. Because of the difficulty of inducing auxotrophic markers via mutagenesis in this species, most previous studies have utilized antibiotic resistance and naturally occurring (auxotypic) auxotrophic markers. We have succeeded in isolating auxotrophic and temperature-sensitive mutants. The temperature-sensitive mutants have been characterized by their growth on complex and defined media at 31, 37, and 40 degrees C. Two of the mutants exhibited an unusual pattern of temperature sensitivity--growth on the defined medium but absence of growth on the complex medium at 37 degrees C. Both mutants, however, were temperature-sensitive on the two media at 40 degrees C. We have demonstrated linkages between markers isolated in our laboratory and the auxotypic markers of the clinical isolate RUG208. Ts-2 exhibited 85 to 95% linkage to Arg- and his-2 exhibited 40% linkage to Val-. In addition weak linkages were shown between his-2 and Arg- (2 to 6%) and between Arg- and Val- (3 to 5%). Linkages among his-2, Arg-, and Val- which could be demonstrated when deoxyribonucleic acid from strain F62 was used to transform RUG208 were absent when F62 was used as recipient for RUG208 DNA. Our data are consistent with a tentative map order of his-2, Val-, Arg-, Ts-2.
Location of a ColE1 deoxyribonucleic acid region that affects the plaque-forming ability of lambda-ColE1 hybrid bacteriophage
Authors: Takeya T , Shimada K , Oka A , Takagi Y
Published: January 2020

The plaque-forming ability of a hybrid phage between plasmidColE1 and phage lambda carrying amber mutations in genes O and P was inhibited by the presence of ColE1 in suppressor-deficient Escherichia coli cells. ColE1 deoxyribonucleic acid regions concerned with this inhibition were examined by using various deletion and transposon insertion derivatives of ColE1, and it was found that the presence of the deoxyribonucleic acid region extending between 420 and 613 base pairs upstream from the initiation site of ColE1 deoxyribonucleic acid replication (J. Tomizawa, H. Ohmori, and R. E. Bird, Proc. Natl. Acad. Sci. U. S. A. 74: 1865--1869, 1977) was essential for this function.