bluuebunny/crossref_metadata_2025 huggingface dataset:
Whole-cell and membrane lipids of the methylotrophic bacterium Methylosinus trichosporium
Authors: Weaver T L , Patrick M A , Dugan P R
Published: January 2020

The lipid composition of the methylotrophic bacterium Methylosinus trichosporium was examined. Whole-cell lipid distribution was 39.1% neutral lipids, 34.5% polar lipids, and 26.4% poly-beta-hydroxybutyric acid. Membrane lipids were 83% phospholipids, with phosphatidylethanolamine and phosphatidylglycerol accounting for over 94% of the total. All the phospholipids had similar fatty acid compositions, with 18:1 accounting for about 87% of the total and most of the rest consisting of 16:1. Similarities between the lipid composition of this bacterium and other bacteria are discussed.
Isolation, characterization, and mapping of Escherichia coli mutants blocked in the synthesis of ornithine decarboxylase
Authors: Cunningham-Rundles S , Maas W K
Published: January 2020

Several Escherichia coli K-12 mutants blocked in the synthesis of ornithine decarboxylase (OD) were isolated after transduction for serA+ in a strain (MA197) blocked in agmatine ureohydrolase (AUH) with a mutagenized phage lysate of P1. The new double-polyamine mutants were characterized by an unconditional polyamine dependence; either putrescine or spermidine was required for normal growth. The mutational block was varified by the demonstration of a virtual absence of OD activity in cellular extracts. The mutation, designated speC, was mapped by P1 transduction in several strains and was shown to have a cotransduction frequency of 17.2% with serA. Map order was established as serA speB speC metK. A derivative of one of the OD mutants having wild-type levels of AUH and blocked in OD was utilized along with an OD AUH mutant and an OD+ AUH strain to explore the phenomenon of "pathway selection" using growth rate as a parameter. Polyamine pool studies were carried out simultaneously. The results presented here support the hypothesis of pathway selection, implying a preferential utilization of exogenous arginine rather than endogenously produced arginine in polyamine biosynthesis.
Genetic analysis of drug resistance in Neisseria gonorrhoeae: production of increased resistance by the combination of two antibiotic resistance loci
Authors: Maier T W , Zubrzycki L , Coyle M B , Chila M , Warner P
Published: January 2020

The studies reported here demonstrate that increased resistance of Neisseria gonorrhoeae to penicillin, tetracycline, and chloramphenicol results from the combined effect of two resistance loci. As shown by experiments with deoxyribonucleic acid from transformants carrying only a single resistance locus, transformants with an incresed level of resistance to penicillin result from the combination of a penicillin-specific locus, pen, and a multiple resistance locus, mtr. Similarly, transformants with an increased level of resistance to tetracycline result from the combination of mtr and a tetracycline-specific locus, tet. Transformants with an increased level of resistance to chloramphenicol result from the combination of mtr and a chloramphenicol-specific locus, cml. Deoxyribonucleic acid dilution experiments established that only a single dose of each of the two required resistance loci is necessary to give higher-level resistance. Higher-level-resistant transformants were not obtained when a double dose of one resistance locus or a combination of loci pairs other than mtr and pen, mtr and tet, or mtr and cml was introduced into a recipient. Combinations of the mtr and tet genes resulted in increased resistance to semisynthetic tetracyclines. The presence of the mtr and pen genes resulted in increased resistance to penicillinase-stable penicillins.
Gene dosage effects in polyploid strains of Saccharomyces cerevisiae containing gua-1 wild-type and mutant alleles
Authors: Reichert U , Winter M
Published: January 2020

Triploid and tetraploid Saccharomyces strains containing different combinations of a gua-1 mutant allele and the corresponding wild type were prepared. The cultivation of the different strains in media upon which the mutant fails to grow leads to a pronounced growth rate response to the dosage of the wild-type allele. Proportionality between the specific activity of the guanosine 5'-monophosphate synthetase and the wild-type dosage was reavealed. Inosine 5'-monophosphate dehydrogenase, the precursor enzyme in the pathway, is derepressed in a sigmoid manner when the wild-type dosage is reduced, whereas the activity of cytosine deaminase, investigated as a reference enzyme, is less affected.
Electron-transferring flavoprotein of Peptostreptococcus elsdenii that functions in the reduction of acrylyl-coenzyme A
Authors: Brockman H L , Wood W A
Published: January 2020

In Peptostreptococcus elsdenii, a three-component flavoprotein electron transfer system catalyzes the oxidation of lactate and the reduction of crotonyl-coenzyme A (CoA). Spectral evidence showed that D-lactate dehydrogenase, when reduced by D-lactate, was able to reduce butyryl-CoA dehydrogenase, but only in the presence of the electron-transferring flavoprotein. Reduced nicotinamide adenine dinucleotide could replace reduced D-lactate dehydrogenase. A reconstituted system, containing the three partially purified enzymes, excess D-lactate, and a limiting amount of crotonyl-CoA, reduced the crotonyl-CoA to butyryl-CoA, but only if all components were present. The electron-transferring flavoprotein activity, purified 22-fold, was separated into two major flavoprotein components, A and B, after polyacrylamide gel electrophoresis. Elution of the proteins and subsequent kinetic assays of the eluates showed that component B catalyzes the reduction of butyryl-CoA dehydrogenase by reduced D-lactate dehydrogenase, whereas component A does not. Both A and B catalyzed the reduction of butyryl-CoA dehydrogenase by reduced nicotinamide adenine dinucleotide. The results suggest that the D-lactate dehydrogenase-dependent reduction involves a heretofore unrecognized component of the electron-transferring protein group which may utilize an unusual flavin, 6-hydroxy-7,8-dimethyl-10-(ribityl-5'-adenosine diphosphate)-isoalloxazine.
Mannitol transport in Streptococcus mutans
Authors: Maryanski J H , Wittenberger C L
Published: January 2020

A hexitol-inducible, phosphoenolpyruvate-dependent phosphotransferase system was demonstrated in Streptococcus mutans. Cell-free extracts obtained from mannitol-grown cells from a representative strain of each of the five S. mutans serotypes (AHT, BHT, C-67-1, 6715, and LM7) were capable of converting mannitol to mannitol-1-phosphate by a reaction which required phosphoenolpyruvate and Mg2+. Mannitol and sorbitol phosphotransferase activities were found in cell-free extracts prepared from cells grown on the respective substrate, but neither hexitol phosphotransferase activity was present in extracts obtained from cells grown on other substrates examined. A heat-stable, low-molecular-weight component was partially purified from glucose-grown cells and found to stimulate the mannitol phosphotransferase system. Divalent cations Mn2+ and Ca2+ partially replaced Mg2+, while Zn2+ was found to be highly inhibitory.
Comparison of lipopolysaccharides from Agmenellum quadruplicatum to Escherichia coli and Salmonella typhimurium by using thin-layer chromatography
Authors: Buttke T M , Ingram L O
Published: January 2020

Lipopolysaccharide (LPS) was isolated from the unicellular blue-green bacterium Agmenellum quadruplicatum using the procedure of Westphal and Jann (1965). It was composed of a lipid A and polysaccharide region suggesting a similarity to other gram-negative LPSs. Chemical analyses demonstrated the presence of glucose, rhamnose, mannose, and xylose in the polysaccharide region, as well as 2-keto-3-deoxyoctonate, glucosamine, and phosphorous in the lipid A. Studies on the lipid composition revealed the presence of palmitic, behenic, and three beta-hydroxy fatty acids. A new procedure for thin-layer chromatography of bacterial LPSs was used to compare LPS from A. quadruplicatum to other gram-negative organisms. The method is capable of distinguishing between LPSs of different bacteria as well as between the wild-type organism and mutated forms unable to synthesize complete LPS. A comparison of LPS from A. quadruplicatum to Escherichia coli and Salmonella typhimurium demonstrated that, although the blue-green LPS was rather similar to that of the Enterobacteriaceae, distinct differences also existed. However, when several cell division mutants of A. quadruplicatum were compared chromatographically to the parent strain BG-1, no differences were observed. This suggests that cell division mutations in A. quadruplicatum are not associated with changes in the LPS.
Simple and sensitive procedure for screening yeast mutants that lyse at nonpermissive temperatures
Authors: Cabib E , Duran A
Published: January 2020

After mutagenesis, surviving yeast cells are grown on plates at 25 C and later exposed to 37 C. The plates are then overlaid with a soft agar containing p-nitrophenylphosphate at pH 9.7. Lysed cells liberate alkaline phosphatase which gives rise to a yellow color on and around colonies.
Linkage of Six Genes in
Chlamydomonas reinhardtii
and the Construction of Linkage Test Strains
Authors: Smyth Robert D. , Martinek George W. , Ebersold W. T.
Published: January 2020

Linkage relationships were determined for six genes in
Chlamydomonas reinhardtii
:
pyr, act, can-la, ey, y-1
, and
nic-7
. Four of these were combined with five other genes to form linkage test strains.
Synthesis of polyadenylic acid-containing ribonucleic acid during the germination of Neurospora crassa conidia
Authors: Mirkes P E , McCalley B
Published: January 2020

Ribonucleic acid (RNA) synthesized during the first 1 h of conidial germination (15 to 20, 25 to 30, and 55 to 60 min) has been characterized by sucrose-sodium dodecyl sulfate gradient centrifugation, binding to polyuridylic acid filters, and oligo(dT)-cellulose chromatography. At all labeling periods examined, polyadenylic acid-containing RNA is synthesized, processed, and incorporated into polysomes. Approximately 40% of the labeled RNA sedimenting between 5 and 17S binds to polyuridylic acid filters. RNA which binds to oligo(dT)-cellulose displays a heterogeneous distribution in sucrose-sodium dodecyl sulfate gradients with a major, broad peak at 10-16S. In addition, some polyadenylic acid-containing RNA sediments beyond the 25S marker. Approximately 3% of the [3H]adenosine in pulse-labeled polysomal RNA is in polyadenylic acid segments resistant to pancreatic and T1 ribonucleases.
Energy coupling in the active transport of amino acids by bacteriohodopsin-containing cells of Halobacterium holobium
Authors: Hubbard J S , Rinehart C A , Baker R A
Published: January 2020

Growth of Halobacterium halobium under illumination with limiting aeration induces bacteriorhodopsin formation and renders the cells capable of photophosphorylation. Cells depleted of endogenous reserves by a starvation treatment were used to investigate the means by which energy is coupled to the active transport of [14C]proline, -leucine, and -histidine. Proline was readily accumulated by irradiated cells under anaerobiosis even when the photophosphorylation was abolished by the adenosine triphosphatase inhibitor N,N'-dicyclohexylcarbodimiide (DCCD). The uptake of proline in the dark was limited except when the cells were allowed to accumulate adenosine 5'-triphosphate (ATP) by prior light exposure or by the oxidation of glycerol. DCCD inhibited this dark uptake. These findings essentially support Mitchell's chemiosmotic theory of active transport. The driving force is apparently the proton-motive force developed when protons are extruded from irradiated bacteriorhodopsin or by the dydrolysis of ATP by membrane adenosine triphosphatase. Carbonylcyanide m-chlorophenylhydrazone (CCCP), a proton permeant known to abolish membrane potential, was a strong inhibitor of proline uptake. Leucine transport was also apparently driven by proton-motive force, although its kinetic properties differed from the proline system. Histidine transport is apparently not a chemiosmotic system. Dark- or light-exposed cells show comparable initial rats of histidine uptake, and these processes were only partially inhibited by DCCD or CCCP. The histidine system apparently does not utilize ATP per se since comparable rates of uptake were exhibited by cells of differing intracellular ATP levels. Irradiated cells did effect a greater total accumulation of histidine than dark-exposed cells. These findings suggest that ATP is needed for sustained transport.
cis-Dominant, transfer-deficient mutants of the Escherichia coli K-12 F sex factor
Authors: Guyer M S , Clark A J
Published: January 2020

Rare conjugational progeny formed by crossing each of five Hfr strains with a recA-F- strain have been characterized. Selection was made for a proximal Hfr marker, taking strict precautions to prevent transfer of recA+ to the zygotes. Most of the progeny were found to be F' strains containing deletion mutant plasmids. With two exceptions, these mutant plasmids have lost all of the tra genes, which are required to confer conjugational donor ability upon a host. In addition, all but the exceptional mutant plasmids were found to be very poorly transmissible from transient heterozygotes which also contain a wild-type F' plasmid. The poor transmissibility is a cis-dominant transfer-defective phenotype which may result from deletion of all or part of the origin of transfer replication (ori), or of a gene determining a cis-acting protein. The two exceptional mutant plasmids may carry short deletions of some of the tra genes or polar tra mutations. The remaining progeny were nonmutant F' strains and F- strains. The frequency with which the F- strains were recovered permits us to estimate that the maximum amount of recombination possible in a recA56 zygote is 10(-6) that of a recA+ zygote.
Increased loss of duplicated genes in streptomycin-resistant (strA) mutants of Escherichia coli k-12
Authors: Simonian M H , Mosteller R D
Published: January 2020

The recombination-dependent loss of a duplicated portion of the Escherichia coli chromosome is five- to tenfold greater in strains containing streptomycin resistance (strA) mutations than in the strA+ parental strain. Streptomycin (500 mug/ml) partially reverses the increase. These results suggest an interaction between strA mutations and recombination.
Plasmid-Determined Ability of a
Salmonella tennessee
Strain to Ferment Lactose and Sucrose
Authors: Johnson E. M. , Wohlhieter J. A. , Placek Bruce P. , Sleet R. B. , Baron L. S.
Published: January 2020

The ability of a
Salmonella tennessee
strain to ferment both lactose and sucrose was attributed to a conjugally transmissible plasmid, deoxyribonucleic acid molecular weight 164 × 10
6
, bearing the genetic determinants of both fermentation characters.
Role and regulation of the ortho and meta pathways of catechol metabolism in pseudomonads metabolizing naphthalene and salicylate
Authors: Barnsley E A
Published: January 2020

The enzymes of naphthalene metabolism are induced in Pseudomonas putida ATCC 17484, PpG7, NCIB 9816, and PG and in Pseudomonas sp. ATCC 17483 during growth on naphthalene or salicylate; 2-aminobenzoate is a gratuitous inducer of these enzymes. The meta-pathway enzymes of catechol metabolism are induced in ATCC 17483 and PPG7 during growth on naphthalene or salicylate or during growth in the presence of 2-aminobenzoate, but in ATCC 17484 and NCIB 9816 the ortho-pathway enzymes of catechol metabolism are induced during growth on naphthalene or salicylate. 2-Aminobenzoate does not induce any enzymes of catechol metabolism in the latter two organisms. In Pseudomonas PG the meta-pathway enzymes are present at high levels under all conditions of growth, but this organism and PpG7 can induce ortho-pathway enzymes during naphthalene or salicylate metabolism. Salicylate appears to be the inducer of the enzymes of naphthalene metabolism in all of the organisms studied and, where they are inducible, of the meta-pathway enzymes, but the properties of Pseudomonas PG suggest that separate, regulatory systems may exist.
Rare occurrence of the tetratype tetrads in Saccharomycodes ludwigii
Authors: Yamazaki T , Ohara Y , Oshima Y
Published: January 2020

Genetic data suggesting the absence of crossover in Saccharomycodes ludwigii have been described. Tetrad data obtained from 888 asci from 60 pairs of genes with 22 genetic markers showed the absence of tetratype asci, except for 5 asci in which a single pair of alleles showed tetratype segregation to the other genetic markers in each ascus. Spore arrays in the linear asci showed that the + - + - and + - - + (or - + + -) asci occurred at almost equal frequencies. The two coherent spores at each end of an ascus were always marked with different alleles of a gene.
Turnover of polyadenylate-containing ribonucleic acid in Saccharomyces cerevisiae
Authors: Hynes N E , Phillips S L
Published: January 2020

We examined the kinetics of incorporation of [3H]adenine into polyadenylate-containing ribonucleic acid [poly(A)-containing RNA] in yeast. The total poly(A)-containing RNA from spheroplasts and intact cells and the polysomal poly(A)-containing RNA exhibited similar incorporation kinetics. At 30 C half-saturation of the pool of poly(A)-containing RNA with label occurred in approximately 22 min. Since precursor pools appeared to require 5 min to saturate with label, we conclude that at 30 C messenger RNA molecules in yeast decay with an average half-life of 17 min.
Derepression of certain aromatic amino acid biosynthetic enzymes of Escherichia coli K-12 by growth in Fe3+-deficient medium
Authors: McCray J W , Herrmann K M
Published: January 2020

3-Deoxy-arabino-heptulosonic acid 7-phosphate synthase, prephenate dehydratase, tryptophan synthase, and 2,3-dihydroxybenzoylserine synthase enzyme activities are derepressed in wild-type Escherichia coli K-12 cells grown on Fe3+-deficient medium. This derepression is reversed when FeSO4 is added to the growth medium. Addition of shikimic acid to the Fe3+-deficient growth medium caused repression of the first three enzyme activities but not of 2,3-dihydroxybenzoylserine synthase activity. Addition of 2,3-dihydroxybenzoic acid to the Fe3+-deficient growth medium has no effect on any of the above-mentioned enzyme activities. The Fe3+ deficiency-mediated derepression of 3-deoxyarabino-heptulosonic acid 7-phosphate synthase activity is due to an elevation of the tyrosine-sensitive isoenzyme; the phenylalanine-sensitive isoenzyme is not derepressed under these conditions.
Ultrastructure of superficial mycosidic integuments of Mycobacterium sp
Authors: Kim K S , Salton M R , Barksdale L
Published: January 2020

Cells from pellicle growth of Mycobacterium sp. NQ are enveloped in a mycoside layer which extends outward as long filaments, 5 nm in diameter. Underneath this outer mycosidic casement, ramified ropelike structure, embedded in a dense matrix, overlay the rigid peptidoglycan of the cell wall.
Physiological factors affecting transformation of Azotobacter vinelandii
Authors: Page W J , Sadoff H L
Published: January 2020

Cells of Azotobacter vinelandii (ATCC 12837) can be transformed by exogenous deoxyribonucleic acid towards the end of exponential growth. Transformation occurs at very low frequencies when the deoxyribonucleic acid is purified or when the transformation is carried out in liquid medium. Optimal transformation occurs on plates of Burk nitrogen-free glucose medium containing either high phosphate (10 mM) or low calcium (0 to 0.29 mM) content. Higher levels of calcium are inhibitory, whereas magnesium ions are essential for transformation and growth. Extracellular polymer and capsule are increasingly inhibitory to transformation and are most abundant when the calcium content of the medium is high. Transformation is optimal at pH 7.0 to 7.1 and at 30 C, conditions which also coincide with minimal extracellular polymer production. Nonencapsulated strains are excellent transformation recipients. Glycine-induced pleomorphism reduces the transformation frequency and the degree of inhibition is dependent on the phosphate concentration of the medium. Rifampin resistance and shifts from adenine, hypoxanthine, uracil, and nitrogenase auxotrophy to prototrophy can be achieved. Although single marker transfer is always greater than double marker transfer, the data suggest that rifampin resistance is linked to hypoxanthine, adenine and uracil protorophy at intervals of increasing distance. Rifampin resistance did not appear to be linked to nitrogenase.
Ultrastructure of rigid and lignified forage tissue degradation by a filamentous rumen microorganism
Authors: Akin D E
Published: January 2020

A small (less than 1 mum)-filamentous, branching microorganism was observed in Gram-stained smears of the rumen microflora and was found to degrade tissues in forage samples incubated in vitro and in vivo with rumen fluid and observed by scanning and transmission electron microscopy. The microbe had prokaryotic cytoplasmic features and a gram-positive type of cell wall structure. Round to oval bodies apparently attached to hyphae resembled the sporulation pattern reported for Micromonospora. Filaments and rod and coccal forms of the microbe degraded rigid forage cell walls and lignified, thick-walled sclerenchymal cells. Location of the microbe at a slight distance from the degraded zones suggested the action of extracellular enzymes. The presence of a microbe with the capability of degrading lignified tissue represents an important and unique function in the rumen ecosystem.
Change in quantity of lipids and cell size during intracytoplasmic membrane formation in Gluconobacter oxydans
Authors: Heefner D L , Claus G W
Published: January 2020

Electron microscopy previously revealed that Gluconobacter oxydans differentiates by forming quantities of intracytoplasmic membranes at the end of exponential growth. It was also shown that the formation of these membranes appears concurrently with an increased rate of polyol oxidation. In the present study, exponential-phase cells devoid of intracytoplasmic membranes were harvested and the quantity of free lipid was determined. This quantity was compared with that extracted from cells harvested 4 and 16 h into the stationary phase that contained intracytoplasmic membranes. Cells harvested 4 and 16 h into the stationary phase contained 58 and 43% more free lipid per 100 mg of cell weight than found in undifferentiated exponential-phase cells. These same cultures were used to compare the quantity of lipid extracted per cell. This analysis revealed 89 and 142% more lipid per cell in 4 and 16 h stationary-phase cells. Further study demonstrated that cells increased in length and decreased in density with time after they entered the stationary phase. We estimated, however, that intracytoplasmic membrane development in G. oxydans is accompanied by a 57 to 62% increase in free-lipid that cannot be attributed to a change in cell size. These results suggest that the traditional expression of extracted lipid per milligram of cellular dry weight should not be used for comparative purposes during differentiation in gram-negative bacteria, unless it is first established that both cell size and cell density remain constant throughout differentiation.
Morphological study of the reversion to bacillary form, of Bacillus megaterium protoplasts
Authors: Hadlaczky G , Fodor K , Alföldi L
Published: January 2020

Protoplasts of Bacillus megaterium readily reverted to bacillary form in liquid media and when plated in a soft-agar layer onto the surface of appropriate agar media. Three phases of the reversion sequence could be differentiated by phase contrast microscopy: (i) increase in size of the individual protoplasts, (ii) non oriented division of the protoplasts and (iii) outgrowth of the bacillary forms. With time-lapse photomicrography, reversion sequences of single protoplasts were demonstrated.
Immunofluorescent polar tips of Rhizobium japonicum: possible site of attachment or lectin binding
Authors: Bohlool B B , Schmidt E L
Published: January 2020

Rhizobium japonicum USDA 31 demonstrated marked polarity by binding homologous fluorescent antibody (FA) heavily on one end of the cell. FA prepared against R. japonicum strains 110 and 138, and against R. trifolii TA1 cross-reacted with strain 31 only in the polar tip region. No polar immunofluorescing tips could be seen with FA against two other strains of R. japonicum or with those against several unrelated microorganisms. Common antigens localized only in a polar region were seen in many rhizobia stained with R. japonicum 31 FA: 22 of 23 strains of R. japonicum, 10 of 17 strains of R. trifolii, 3 of 7 strains of R. melitolii, 3 of 6 strains of R. phaseoli, and 3 of 9 strains of R. leguminosarum had some cells with detectable polar tips. The proportion of R. japonicum 31 cells with polar tips was high throughout the growth cycle. Polar tip staining was not affected by drastic cell treatments. A function was proposed for the polar tip region as a site for attachment. R. japonicum 31 cells attached to each other in a tip-to-tip fashion and endwise to fungal hyphae with the polar tip in contact with the hyphal wall. Binding of fluorescein isothiocyanate-labeled soybean lectin to certain strains of R. japonicum gave additional evidence of polarity. Polar binding of both antibody and lectin may provide insights into relationships between rhizobia and roots of host legumes.
In vitro synthesis of the unit that links teichoic acid to peptidoglycan
Authors: Hancock I , Baddiley J
Published: January 2020

The role of cytidine diphosphate (CDP)-glycerol in gram-positive bacteria whose walls lack poly(glycerol phosphate) was investigated. Membrane preparations from Staphylococcus aureus H, Bacillus subtilis W23, and Micrococcus sp. 2102 catalyzed the incorporation of glycerol phosphate residues from radioactive CDP-glycerol into a water-soluble polymer. In toluenized cells of Micrococcus sp. 2102, some of this product became linked to the wall. In each case, maximum incorporation of glycerol phosphate residues required the presence of the nucleotide precursors of wall teichoic acid and of uridine diphosphate-N-acetylglucosamine. In membrane preparations capable of synthesizing peptidoglycan, vancomycin caused a decrease in the incorporation of isotope from CDP-glycerol into polymer. Synthesis of the poly (glycerol phosphate) unit thus depended at an early stage on the concomitant synthesis of wall teichoic acid and later on the synthesis of peptidoglycan. It is concluded that CDP-glycerol is the biosynthetic precursor of the tri(glycerol phosphate) linkage unit between teichoic acid and peptidoglycan that has recently been characterized in S. aureus H.
Effects of chloramine on Bacillus subtilis deoxyribonucleic acid
Authors: Lu Shih K , Lederberg J
Published: January 2020

The lesions induced in Bacillus subtilis deoxyribonucleic acid (DNA) after treating bacterial cells (in vivo) and bacterial DNA (in vitro) with chloramine were studied biologically and physically. Single-strand breaks and a few double-strand scissions (at higher chloramine doses) accompanied loss of DNA-transforming activity in both kinds of treatments. Chloramine was about three times more efficient in vitro than in vivo in inducing DNA single-strand breaks. DNA was slowly chlorinated; the subsequent efficiency of producing DNA breaks was high. Chlorination of cells also reduced activity of endonucleases in cells; however, chlorinated DNA of both treatments was sensitized to cleavage by endonucleases. The procedure of extracting DNA from cells treated with chloramine induced further DNA degradation. Both treatments introduced a small fraction of alkali-sensitive lesions in DNA. DNA chlorinated in vitro showed further reduction in transforming activity as well as further degradation after incubation at 50 C for 5 h whereas DNA extracted from chloramine-treated cells did not show such a heat sensitivity.
Role of iron deposition in Sphaerotilus discophorus
Authors: Rogers S R , Anderson J J
Published: January 2020

Various physiological aspects of the process of iron deposition in Sphaerotilus discophorus were examined to elucidate its role. The values of iron/protein ratios suggested that a direct relationship existed between the iron concentration of the media and the magnitude of final iron deposition. Saturation of the organism's iron deposition system occurred at a 2.0 mM iron concentration, at a value of 0.6 mg of ferric ion per mg of cell protein. Laboratory data indicated that the strain's very low capacity for iron deposition observed at low external iron concentrations makes it unlikely that it is significant in limiting iron in the natural milieu. Under optimal iron concentrations, however, strain SS1 caused precipitation of iron (adsorbed to cellular material) in broth cultures, which was 10 to 100 times that mediated by some "non-iron" microorganisms. The strain's iron requirement, which was found to be between 0.003 and 0.02 mM, is commensurate with that of other microbes. One hundred micrograms of Mn(II) per ml and possibly 10 mug of either Co(II) or Ni(II) per ml could inhibit iron uptake in the deposition system. Sphaerotilus, when tested for its ability to withstand toxic concentrations of certain trace elements (Co, Cu, Mn, Ni, and Cd), demonstrated no exceptional resistance with respect to several other common microorganisms. Final cell yields were not affected by a varying iron concentration for Sphaerotilus growing under conditions of limiting carbon and nitrogen.
Study on development of Agaricus bisporus by fluorescent microscopy and scanning electron microscopy
Authors: Saksena K N , Marino R , Haller M N , Lemke P A
Published: January 2020

Two strains of Agaricus bisporus have been investigated by fluorescent microscopy and scanning electron microscopy. Somatic nuclei, stained with auramin O and examined by fluorescent microscopy, appear to be randomly distributed, divide asynchronously, and assume a nonclassical or "two-track" configuration during mitotic metaphase. A similar configuration has been observed for nuclei during meiosis, but early meiosis in A. bisporus appears to be classical, usually with nine pairs of chromosomes evident during prophase I. Scanning electron microscopy has been used to document developmental stages in the formation and germination of basidiospores. Two-spored basidia were predominant, but occasionally one- or three-spored forms were observed. Four-spored basidia were absent, and uninucleated basidiospores were exceedingly rare to absent.
Growth rate modulation of four aminoacyl-transfer ribonucleic acid synthetases in enteric bacteria
Authors: McKeever W G , Neidhardt F C
Published: January 2020

The specific activities of arginyl- glutamyl- seryl-, and valyl-transfer ribonucleic acid (tRNA) synthetases were measured in the wild-type and mutant strains of Salmonella typhimurium LT2 and Escherichia coli B/r. In media restricted only by carbon and energy source availability, the specific activities of all four enzymes were proportional to the growth rate, with the exception of seryl-tRNA synthetase in S. typhimurium, which remained essentially constant. Structural gene densities were calculated for these four enzymes and were found not to account for the variation of specific activity with growth rate.
Methyl methane sulfonate-sensitive mutant of Escherichia coli deficient in an endonuclease specific for apurinic sites in deoxyribonucleic acid
Authors: Ljungquist S , Lindahl T , Howard-Flanders P
Published: January 2020

A methyl methane sulfonate (MMS)-sensitive mutant of Escherichia coli AB 1157 was obtained by N-methyl-N'-nitro-N-nitrosoguanidine treatment. The mutant strain, AB 3027, is defective both in endonuclease activity for apurinic sites in deoxyribonucleic acid (DNA) and in DNA polymerase I, as shown by direct enzyme assays. Derivative strains, which retained the deficiency in endonuclease activity for apurinic sties (approximately 10% of the wild-type enzyme level) but had normal DNA polymerase I activity, were obtained by P1-mediated transduction (strain NH5016) or by selection of revertants to decreased MMS sensitivity. These endonuclease-deficient strains are more MMS-sensitive than wild-type strains. Revertants of these deficients strains to normal MMS resistance were isolated. They had increased levels of the endonuclease activity but did not attain wild-type levels. The data suggest that endonuclease for apurinic sites is active in repair of lesions introduced in DNA as a consequence of MMS treatment. Two different endonucleases that specifically attack DNA containing apurinic sites arepresented in E coli K-12. A heat-labile activity, sensitive to inhibition by ethylenediaminetetraacetate, accounts for 90% of the total endonuclease activity for apurinic sties in crude cell extracts. The residual 10% is due to a more heat-resistant activity, refractory to ethylenediaminetetraacetate inhibition. The AB3027 and NH5016 strains have normal amounts of the latter endonuclease but no or very little of the former activity.
Determination of the execution points of mutations in the nuclear replication cycle of Aspergillus nidulans
Authors: Orr E , Rosenberger R F
Published: January 2020

Cultures of nuclear replication cycle mutants of Aspergillus nidulans were transferred to the nonpermissive temperature, and the fraction of nuclei still able to reach mitosis was determined. For the determinations, benomyl [methyl-1(butylcarbomoyl)benzimidazolecarbamate] was added to trap nuclei in mitosis, and these were detected by staining with aceto-orcein. The assumptions and controls required to relate the experimentally determined fractions to the points where a mutation blocks the nuclear cycle are discussed. Nine genetically distinct mutants were tested. Two of these were blocked early in the cycle, two in the middle, and five close to, or during, mitosis.
Cortex content of asporogenous mutants of Bacillus subtilis
Authors: Imae Y , Strominger J L
Published: January 2020

A method for the measurement of muramic lactam, which is specifically located in the cortical peptidoglycan of bacterial spores, was developed as a quantitative assay method for spore cortex content. During sporulation of Bacillus subtilis 168, muramic lactam (i.e., spore cortex) began to appear at state IV of sporulation and continued to increase over most of the late stages of sporulation. Spore cortex contents of various spo mutants of B. subitils were surveyed. Cortex was not detected in mutants in which sporulation was blocked earlier than stage II sporulation. Spores of spo IV mutant had about 40% of the cortex content of the wild-type spores. One spo III mutant had a low amount of cortex, but four others had none.
Autolysis of Neisseria gonorrhoeae
Authors: Elmros T , Burman L G , Bloom G D
Published: January 2020

Autolysis of Neisseria gonorrhoeae was studied under different conditions. It was found that low pH and temperature, as well as the presence of divalent cations, spermine, sucrose, and polyvinylpyrrolidone, stabilized nongrowing gonococci. Ethylenediaminetetraacetic acid alone promoted lysis, whereas lysozyme had only a limited additive effect. The autolytic behavior of gonococci appears to be connected with their prolonged cell division process. The relative dependence on the outer membrane and the peptidoglycan layer for the mechanical stability of gonococci is discussed.
Compartmentation and control of arginine metabolism in Neurospora
Authors: Weiss R L
Published: January 2020

The fate of [14-C]arginine derived from the medium or from biosynthesis has been examined in Neurospora growing in arginine-supplemented medium. In both cases the label enters the cytosol, where it is used efficiently for both protein synthesis and catabolism before mixing with the majority of the endogenous [12C]arginine pool. Both metabolic processes appear to use the same cytosolic arginine pool. It is calculated that the nonorganellar cytoplasm contains approximately 20% of the intracellular arginine pool when the cells are growing in arginine-supplemented medium. The results suggest that compartmentation of arginine is a significant factor in controlling arginine metabolism in Neurospora. The significance of these results for studies of amino acid metabolism in other eukaryotic systems is discussed.
Carnitine biosynthesis in Neurospora crassa: enzymatic conversion of lysine to epsilon-N-trimethyllysine
Authors: Rebouche C J , Broquist H P
Published: January 2020

The enzymatic conversion of L-lysine, epsilon-N-trimethyl-L-lysine the first series of reactions in the biosynthesis of carnitine in Neurospora crassa, proceeds via sequential methylation of free L-lysine, epsilon-N-methyl-L-lysine, and epsilon -N-dimethyl-L-lysine. The latter two compounds have been shown to be intermediates in the biosynthesis of carnitine by radioisotope dilution and incorporation experiments in growing cultures of N. crassa 33933 (lys-) and 38706 (met-). Methionine but not choline, has been recognized as an effective methyl donor in vivo. Inclusion of choline in the growth medium of strain 33933 does, however, enhance incorporation of the methyl groups of L-[methyl-3H]methionine into carnitine in an apparent "sparing" effect on methionine synthesis. Studies in cell-free extracts of the lysine auxotroph strain 33933 of N. crassa have established that lysine and epsilon-N-methyl and epsilon-N-dimethyllysine are enzymatically methylated, with S-adenosyl-L-methionine as the methyl group donor. The enzyme system appears to have no essential cofactors. Lysine does not induce synthesis of the enzyme system in the wild-type strain 262, whereas both carnitine and epsilon-N-trimethyllysine repress its synthesis in strain 33933.
Suppression of an Escherichia coli dnaA mutation by the integrated R factor R.100.1: Change of chromosome replication origin in synchronized cultures
Authors: Bird R E , Chandler M , Caro L
Published: January 2020

We have followed, by deoxyribonucleic acid-deoxyribonucleic acid hybridization, the order of replication of three chromosomal markers during a synchronous round of replication in three strains of Escherichia coli carrying a dnaAts mutation: one strain in which the F-like R factor R.100.1 was established as a plasmid and two strains in which the dnaA mutation was suppressed by the integration of R.100.1 into the chromosome. In the R+ strain at 30C, replication of the plasmid took place simultaneously with the initiation of chromosome replication at the normal origin. In the integratively suppressed Hfr strains, at 42.5 C, chromosome replication was initiated preferentially from the integrated plasmid; little or no initiation occurred at the normal origin. Similar results were obtained for the one strain tested at 30 C. For both Hfr strains at 42.5 C, the data suggest that at least part of the population replicated bidirectionally. This conclusion had been confirmed using an autoradiographic procedure. Both types of experiment indicate a wide variation in the rate of travel of individual replication forks within the population.
Electrophoretic comparison of endonuclease-digested plasmids from Neisseria gonorrhoeae
Authors: Foster R S , Foster G C
Published: January 2020

In order to associate virulence in Neisseria gonorrhoeae with an alteration of the nucleotide sequence of its small covalently closed plasmid, plasmid deoxyribonucleic acid was isolated from both virulent (T1) and avirulent (T3) morphological types for two strains. Electrophoretic and contour length measurements of intact plasmids indicated a homogeneous population with a molecular weight of approximately 2.6 x 10(6). Digestion with two restriction endonucleases. Hinf I and Hpa II, generated distinct fragment patterns which in each case were identical for T1 and T3 plasmid molecules from the same strain. The analysis suggests no sequence differences between the plasmids from virulent and avirulent types. For both strains, however, a deletion or addition of about 1.5% of the total deoxyribonucleic acid appeared in the Hpa II C digestion fragment when patterns for gonococci serially passaged 300 times were compared to those for bacteria freshly established from frozen stocks. The significance of the plasmid instability remains undetermined.
Partial Characterization of a Temperature-Sensitive Mutation Affecting Acetyl Coenzyme A Carboxylase in
Escherichia coli
K-12
Authors: Silbert David F. , Pohlman Timothy , Chapman Ann
Published: January 2020

A temperature-sensitive mutation in
Escherichia coli
K-12 was shown to affect acetyl coenzyme A carboxylase and to map at min 63. This site is designated
fabE
.
Lipids of Branhamella catarrhalis and Neisseria gonorrhoeae
Authors: Beebe J L , Wlodkowski T J
Published: January 2020

Three strains of Branhamella catarrhalis and three strains of Neisseria gonorrhoeae were analyzed with regard to their phospholipid and neutral lipid composition. B. catarrhalis (ATCC 23246) contained 5.12 +/- 0.34% lipid, determined gravimetrically, compared to 8.56 +/- 0.15% and 9.73 +/- 0.06% for two strains of N. gonorrhoeae. Cardiolipin, phosphatidylglycerol, and phosphatidyl-ethanolamine were identified in extracts of both species. In addition, B. catarrhalis contained small amounts of phosphatidylcholine, and N. gonorrhoeae contained small amounts of lyso-phosphatidylethanolamine, which accumulated with autolysis accompanying late cell culture growth. The kinetics of change of relative amounts of phospholipids in both species were measured and found to differ substantially. Neutral lipid accounted for 30.4% of the total lipid of B. catarrhalis (ATCC 23246) and 7.6% of the total lipid of N. gonorrhoeae NYH 002. Hydrocarbons, triglycerides, free fatty acids, coenzyme Q, diglycerides, and free hydroxy fatty acids were identified in the neutral lipid fraction of both species. The three strains of N. gonorrhoeae, sensitive, intermediate, and resistant to penicillin, exhibited no significant difference in the composition or metabolism of phospholipid.
Relationship between the transport of iron and the amount of specific colicin Ia membrane receptors in Escherichia coli
Authors: Konisky J , Soucek S , Frick K , Davies J K , Hammond C
Published: January 2020

Strains of Escherichia coli K-12 defective in their ability to utilize exogenously supplied iron due to genetic defects in the entF, tonB, fes, or fep gene exhibited elevated levels of the specific outer-membrane receptor for colicin Ia when compared with parental strains. Although entF, fes, and fep strains showed a higher degree of Ia sensitivity than did the parental strains, tonB strains were resistant to colicin action. The colicin insensitivity of tonB strains was not due to hyperproduction of enterochelin. Growth in medium containing 101.8 muM Fe2+ led to a lowering of receptor levels in all the above strains and resulted in decreased colicin Ia sensitivity in all strains except tonB, which was already at maximal resistance. Growth in citrate plus iron (1.8 muM) or in ferrichrome resulted in a substantial reduction in both receptor levels and Ia sensitivity in ent, fes, and fep strains but had no effect on receptor levels in tonB strains. Growth in citrate did not lead to an alteration in receptor levels in a mutant specifically defective in citrate-mediated iron transport. The presence of enterochelin during growth led to a reduction in the number of receptors in the parental and ent strains but not in tonB, fes, or fep strains. Thus, in all cases examined, there was an inverse relationship between the number of colicin receptors per cell and the ability of the strain to take up iron from the growth medium. This suggests that under conditions of iron limitation there is a derepression of colicin Ia receptor biosynthesis. These results may point to a role of the colicin I receptor in iron uptake.
Biological properties of a Haemophilus influenzae restriction enzyme, Hind I
Authors: Gromkova R , Goodgal S H
Published: January 2020

A type I restriction enzyme from Haemophilus influenzae, Hind I, which requires adenosine 5' -triphosphate and 5-adenosyl methionine, was studied for its activity on transfecting and transforming deoxyribonculeic acid (DNA). The enzyme reduced the size of unmodified bacteriophage S2 DNA from 37 X 10(6) daltons to approximately 10 X 10(6) daltons, but did not affect modified S2 DNA. Unmodified transforming DNA was attacked in vitro by Hind I; however, relatively low levels of inactivation were obtained for single markers, and linked transformants were inactivated as a function of the distance between markers. In contrast, unmodified bacterial DNA was not inactivated in vivo for either single or linked markers by the Hind I restriction system, probably because the segments generated by Hind I were still capable of being integrated in vivo. The lack of preferential inactivation of markers by the enzyme suggests that it makes random breaks in the DNA.
Plasmid-protein relaxation complexes in Staphylococcus aureus
Authors: Novick R
Published: January 2020

Protein-deoxyribonucleic acid relaxation complexes have been demonstrated for six Staphylococcus aureus plasmids out of sixteen examined. Four of these encode stretomycin resistence, have molecular weights of about 2.7 x 10(6), and are isolated as supercoiled molecules that are virtally 100% relaxable by treatment with sodium dodecyl sulfate. It is probable that these four isolates represent a single widely disseminated plasmid species. The other two plasmids showing relaxation complexes have molecular weights of about 3 x 10(6) and encode chloramphenicol resistance. The complexes in these cases are unstable, and it has not been possible to induce more than 50% relaxation by any of the standard treatments. Ten other plasmids do not show detectable complexes. These include three penicillinase plasmids, four tetracycline-resistance plasmids, one plasmid carrying kanamycin-neomycin resistance, and finally, two chloramphenicol-resistance plasmids.
XYL, a nonconjugative xylene-degradative plasmid in Pseudomonas Pxy
Authors: Friello D A , Mylroie J R , Gibson D T , Rogers J E , Chakrabarty A M
Published: January 2020

Pseudomanas Pxy metabolizes p- or m-xylene through intermediate formation of the corresponding methylbenzyl alcohol and toluic acid via the meta pathway. The strain Pseudomonas Pxy spontaneously loses its ability to grow with xylene or toluate, and the rate of loss of this ability is greatly enhanced by treatment of the cells with mitomycin C. The assay of enzymes involved in xylene degradation in xylene-negative Pxy cells indicates the loss of the entire enzyme complement of the pathway. The genes specifying all the xylene-degradative enzymes, including those of the meta pathway, appear to be borne on a nonconjugative plasmid and can be transferred to xylene-negative Pxy or P. putida strain PpG1 cells only in the presence of a transfer plasmid termed factor K. When transferred to strain PpG1, the xylene-degradative plasmid, termed XYL, coexists stably with factor K, but transduction of XYL is not accompanied by a cotransfer of factor K. XYL appears to be compatible wit- all the other known degradative plasmids in P. putida. The xylene pathway is inducible in wild-type Pxy as well as in Pxy and PpG1 exconjugants, suggesting the cotransfer of regulatory genes along with the plasmid. The enzymes converting xylene to toluate are induced by xylene, methylbenzyl alcohol, or the aldehyde derivatives but not significantly by toluate, whereas catechol dioxygenase and other enzymes are induced by toluates and presumable by xylene as well.