bluuebunny/crossref_metadata_2025 huggingface dataset:
Characteristics of a glycerol utilization mutant of Neurospora crassa
Authors: Courtright J B
Published: January 2020

A mutant of Neurospora crassa able to grow on liquid minimal glycerol medium without evidence of conidiation and with high cell yields has been isolated and shown to be allelic to ff-1. The glycerol-specific induction of glycerokinase and glycerol-3-phosphate dehydrogenase was similar in both wild-type and mutant cells, although higher specific activities as well as higher glycerokinase cross-reacting material levels were found in fully induced mutant cells. After growth in minimal glycerol medium there is a significant reduction in wild-type cells of the activities of both pyruvate dehydrogenase and dihydrolipoyl transacetylase. This evidence indicates a relationship between the conditional acetate requirement by wild-type cells grown on glycerol medium and the levels of the pyruvate dehydrogenase complex.
Role for deoxyribonucleic acid ligase in deoxyribonucleic acid polymerase i-dependent repair synthesis in toluene-treated escherichia coli
Authors: Billen D , Hellermann G R , Stallions D R
Published: January 2020

In a toluene-treated mutant of Escherichia coli K-12 having a temperature-sensitive, conditionally lethal mutation in the structural gene for deoxyribonucleic acid (DNA) ligase, an extensive DNA repair synthesis occurred in X-irradiated cells at the nonpermissive temperature, 42 C. At the permissive temperature, 30 C, nearly normal semiconservative synthesis and limited repair synthesis were observed when DNA ligase was activated by the addition of nicotinamide adenine dinucleotide.
Physiological and biochemical studies on the function of 5-methyluridine in the transfer ribonucleic acid of Escherichia coli
Authors: Björk G R , Neidhardt F C
Published: January 2020

Matched pairs of transductant strains differing by the presence of absence of 5-methyluridine (ribothymidine) (m5U) in their transfer ribonucleic acid (tRNA) were used to study the function of this modified nucleoside in Escherichia coli. Ordinary measurements of growth rate in different media revealed no effect of the loss of m5U in tRNA. A gene located close to trmA (the structural cistron for the methyltransferase that produces m5U in tRNA), however, was found to reduce the growth rates significantly, depending on the medium and the temperature of cultivation. Measurement of codon recognition, macromolecular composition, tRNA binding to the ribosome, and the rate of protein chain elongation in vivo indicated no disadvantage caused by the lack of m5U. The regulation of ilv and his operons seemed also to be unaffected by the absence of m5U in the tRNA. In a mixed population experiment, however, cells possessing m5U in their tRNA seemed to have a distinct advantage over cells lacking this modified nucleoside. This experiment provides the first indication of the overall value of m5U in tRNA.
Association of the replication terminus of the Bacillus subtilis chromosome to the cell membrane
Authors: Yamaguchi K , Yoshikawa H
Published: January 2020

A chromosomal segment containing several genetic markers, from metB to thyA, near the replication terminus is associated with the membranous structure of Bacillus subtilis, but markers adjacent to this region, lys, ura, and metC, are not.
Chemosensory responses of a protozoan are modified by antitubulins
Authors: Levandowsky M , Hauser D C , Glassgold J M
Published: January 2020

Modification of a behavioral response of a marine dinoflagellate to chemical cues is described. Negative response to choline was modified by the antitubulins vincristine, vinblastine, griseofulvin, and trifluralin, but not by colchicine. Positive responses to 3,4-dihydroxyphenylalanine were unaffected by these drugs.
Inhibition of Glutamate Transport in
Synechococcus cedrorum
by Glutamine
Authors: Wan A. Y. L. , Floyd K. W. , Hatch M. T.
Published: January 2020

The absence of glutamate transport in glutamine-grown cells of
Synechococcus cedrorum
R7 was due to feedback inhibition and not repression of transport activity.
Pyrimidine biosynthetic enzymes of Salmonella typhimurium, repressed specifically by growth in the presence of cytidine
Authors: Kelln R A , Kinahan J J , Foltermann K F , O'Donovan G A
Published: January 2020

The repressive effects of exogenous cytidine on growing cells was examined in a specially constructed strain in which the pool sizes of endogenous uridine 5'-diphosphate and uridine 5'-triphosphate cannot be varied by the addition of uracil and/or uridine to the medium. Five enzymes of the pyrimidine biosynthetic pathway and one enzyme of the arginine biosynthetic pathway were assayed from cells grown under a variety of conditions. Cytidine repressed the synthesis of dihydroorotase (encoded by pyrC), dihydroorotate dehydrogenase (encoded by pyrD), and ornithine transcarbamylase (encoded by argI). Moreover, aspartate transcarbamylase (encoded by pyrB) became further derepressed upon cytidine addition, whereas no change occurred in the levels of the last two enzymes (encoded by pyrE and pyrF) of the pyrimidine pathway. Quantitative nucleotide pool determinations have provided evidence that any individual ribo- or deoxyribonucleoside mono-, di-, or triphosphate of cytosine or uracil is not a repressing metabolite for the pyrimidine biosynthetic enzymes. Other nucleotide derivatives or ratios must be considered.
Polypeptide nature of growth requirement in yeast extract for Thermoplasma acidophilum
Authors: Smith P F , Langworthy T A , Smith M R
Published: January 2020

The active component(s) in yeast extract required by Thermoplasma acidophilum for growth is polypeptide in nature. A fraction from yeast extract was isolated and partially characterized as one or more peptides of molecular weight about 1,000 containing 8 to 10 amino acids. Although it was composed largely of basic and dicarboxylic amino acids, only one amino group per molecule was free. The polypeptide(s) appeared to bind avidly to cations. No other organic compounds except glucose were needed by Thermoplasma. Among several hundred known compounds tested, only glutathione plus Fe2+ or Fe3+, clostridial ferredoxin, and spinach ferredoxin elicited any growth response.
Comparison of the cell envelope structure of a lipopolysaccharide-defective (heptose-deficient) strain and a smooth strain of Salmonella typhimurium
Authors: Irvin R T , Chatterjee A K , Sanderson K E , Costerton J W
Published: January 2020

The cell envelope structure of Salmonella typhimurium LT2, which has a heptose-deficient lipopolysaccharide (LPS), is significantly different from that of an isogenic strain with a normal LPS. The rough strain, when examined by freeze-etching, lacks most surface structures that are routinely present in the smooth strain (surface particles and flagella) and has few transmemberane studs in the cytoplasmic membrane (those present are generally found in aggregates), and the outer membrane cleavage is substantially stronger than that of the smooth strain. These envelope differences were independent of both growth temperature and culture age. Examination of ultrathin sections indicated that the rough strain has an outer membrane which forms a much more defined double-track artifact than the smooth strain. The addition of MgCl2 to the growth medium of the rough strain decreased the extent of outer membrane cleavage, and flagella became evident in freeze-etched preparations. The presence of supplemental MgCl2 in the growth medium, which resulted in these morphological changes in the rough strain, also produced growth at a previously restrictive temperature and a decrease in the leakage of periplasmic enzymes. The smooth strain was unaltered morphologically or physiologically by MgCl2 under identical conditions. It is suggested that the outer membrane of the rough strain is more planar.
Isolation of 30S and 50S active ribosomal subunits of Bacillus subtilis, Marburg strain
Authors: Guha S , Szulmajster J
Published: January 2020

Active 30S and 50S ribosomal subunits were isolated from Bacillus subtilis. These subunits were able to perform not only protein synthesis in the presence of artificial or natural messenger ribonucleic acid but also the specific functions characteristic of each of the subunits. Thus the 30S subunits alone are able to bind formyl-methionyl-transfer ribonucleic acid, and the 50S subunits carry the peptidyl transferase activity.
Induction of citrate lyase in Enterobacter cloacae grown under aerated conditions and its effect on citrate metabolism
Authors: O'Brien R W
Published: January 2020

Growth of Enterobacter cloacae on K+ citrate under aerated conditions (no detectable oxygen tension in the medium even though it was aerated) was slower (mean generation time, 130 min) than under aerobic conditions (mean generation time, 72 min), but with a faster utilization of citrate, resulting in a molar growth yield of 10.6 g (dry weight) of cells per mol of citrate utilized versus 40 g (dry weight) of cells per mol of citrate utilized for aerobic growth. The rapid utilization of citrate under aerated conditions was apparently due to the induction of citrate lyase and was supported by the finding that cells excreted acetate and a small amount of oxalacetate under aerated conditions, but not under aerobic conditions when the cells were devoid of citrate lyase activity. The activity of oxalacetate decarboxylase in aerated cells was slightly lower than in aerobic cells, indicating that little of the oxalacetate produced by the citrate lyase was metabolized by the decarboxylase. Oxalacetate was probably metabolized by malate dehydrogenase, previously shown to be present in anaerobic and aerobic cells. Thus, about 70% of the citrate was cleaved by the citrate lyase, resulting in little or no production of energy for growth. The remaining citrate was metabolized via the citric acid cycle under aerated conditions, since the cells contained alpha-ketoglutarate dehydrogenase at the same level as in aerobically grown cells. The presence of the other enzymes of the cycle was shown in earlier studies.
Genetic loci responsible for incompatibility on a co-integrate plasmid, R100-1
Authors: Yoshikawa M
Published: January 2020

An R plasmid, R100-1, was mapped previously (Yoshikawa, 1974) by transduction from an integratively suppressed Hfr strain to a recipient with a mutation in gene dnaA. By this method various types of transductants of plasmid R100-1 that exist autonomously or in the integrated state were obtained. Seventy-one such transductants were used in the present study to map gene inc, which is responsible for incompatibility. The results obtained can be explained by either of the following: (i) R100-1 has only a single gene or gene cluster (inc) despite previous work suggesting that this plasmid is a co-integrate of two replicons; (ii) R100-1 possesses more than one inc locus located between the repA and tra loci.
Brevibacterium liquefaciens adenylate cyclase and its in vivo stimulation by pyruvate
Authors: Lynch T J , Tallant E A , Cheung W Y
Published: January 2020

Adenylate cyclase of Brevibacterium liquefaciens depends on pyruvate for activity. Growing in a simple medium containing glucose and DL-alanine, the microorganism excreted pyruvate, which reached 20 mM in the medium at stationary phase. Using [3H]adenosine to label the adenosine 5'-triphosphate pool, we showed that pyruvate in the medium stimulated adenylate cyclase of B. liquefaciens in vivo, in a manner similar to the stimulation observed in vitro. Adenylate cyclase in cells harvested at different phases of growth was equally responsive to exogenous pyruvate, indicating that the allosteric site for pyruvate was present in the enzyme throughout the various phases of cell growth. The specific activity of adenylate cyclase was highest in cells harvested at early log phase; thereafter it declined and was substantially lower at stationary phase. Although adenylate cyclase appears to be activated by pyruvate throughout the life span of the cell, the activity appears not to be critical to cell growth, which was comparable whether the medium contained high or low pyruvate.
Uroporphyrin-accumulating mutant of Escherichia coli K-12
Authors: Săsărman A , Chartrand P , Proschek R , Desrochers M , Tardif D , Lapointe C
Published: January 2020

An uroporphyrin III-accumulating mutant of Escherichia coli K-12 was isolated by neomycin. The mutant, designated SASQ85, was catalase deficient and formed dwarf colonies on usual media. Comparative extraction by cyclohexanone and ethyl acetate showed the superiority of the former for the extraction of the uroporphyrin accumulated by the mutant. Cell-free extracts of SASQ85 were able to convert 5-aminolevulinic acid and porphobilinogen to uroporphyrinogen, but not to copro- or protoporphyrinogen. Under the same conditions cell-free extracts of the parent strain converted 5-aminolevulinic to uroporphyringen, coproporphyrinogen, and protoporphyrinogen. The conversion of porphobilinogen to uroporphyrinogen by cell-free extracts of the mutant was inhibited 98 and 95%, respectively, by p-chloromercuribenzoate and p-chloromercuriphenyl-sulfonate, indicating the presence of uroporphyrinogen synthetase activity in the extracts. Spontaneous transformation of porphobilinogen to uroporphyrin was not detectable under the experimental conditions used [4 h at 37 C in tris(hydroxymethyl)aminomethane-potassium phosphate buffer, pH 8.2]. The results indicate a deficient uroporphyrinogen decarboxylase activity of SASQ85 which is thus the first uroporphyrinogen decarboxylase-deficient mutant isolated in E. coli K-12. Mapping of the corresponding locus by P1-mediated transduction revealed the frequent joint transduction of hemE and thiA markers (frequency of co-transduction, 41 to 44%). The results of the genetic analysis suggest the gene order rif, hemE, thiA, metA; however, they do not totally exclude the gene order rif, thiA, hemE, metA.
Deoxyribonucleic acid modification by intermediate-type modification mutants of Escherichia coli K-12 and B
Authors: Bulkacz J , Roulland-Dussoix D , Boyer H W
Published: January 2020

The modification of bacteriophages grown on r-m+/- restriction and modification mutants of Escherichia coli K-12 or B appears to be related to the number of restriction-specific sites in the viral genome. Bacteriophage fd and its mutant U1 fd, which carry two and one B-specific sites, respectively, are not modified in vivo by rB-mB+/- mutant strains. In vitro treatment of fd RF-B+/- deoxyribonucleic acid (DNA) or U1 fd RF-B+/- DNA by endo R-Eco B results in cleavage of the substrate DNA. Lambda bacteriophage, after growth in r-m+/- mutant host strains (lambda-K+/- or lambda-B+/-), is partially protected from in vivo degradation by wild-type homospecific strains. Its efficiency of plating on these strains is approximately 10(-2). However, a hybrid phi80-lambda phage which carries only one K-specific site (sklambda-1) is not modified by rK-mK+/- strains. Labeled DNAs from lambda-B+/- and lambda-K+/- phages were used as substrates for endo R-Eco B and endo R-Eco K nucleases. Zonal centrifugation analysis of the products of the reactions indicate that rK-mK+/- mutants do not protect lambda DNA from in vitro degradation by endo R-Eco K. In contrast, rB-mB+/- mutants appear to partially protect lambda DNA from attack by endo R-Eco B.
Defective pyocin particles produced by some mutant strains of Pseudomonas aeruginosa
Authors: Shinomiya T , Osumi M , Kageyama M
Published: January 2020

Mutants of Pseudomonas aeruginosa, defective in the production of active R-type pyocins, were isolated from pyocinogenic strains and their products were characterized. Polysheath-like structures were found in induced lysates of 29 out of 42 mutants. Two mutants (strain P15-16 and M189) were found to produce special defective particles, which were characterized in detail. The other 11 mutants did not produce significant amounts of any structure visible under an electron microscope. Serum blocking powers were found in lysates from P15-16 and M189 to significant amounts. Defective particle produced by strain P15-16 lacked the sheath component, whereas M189 had morphological defects at the junction between sheath and baseplate, and also in the architecture of baseplate. Both defective particles could adsorb to the surface of bacteria, that were sensitive to pyocin, at the tip of their fibers without killing cells. All M189 particles attached to the bacteria had the extended sheaths. Therefore, attachment to the bacteria by fibers is not sufficient to kill cells, and contraction of sheath must occur after the initial adsorption by fibers for pyocin to express its biological activity. Defective particles of strain P15-16, which was derived from strain P15 (a pyocin R1 producer), could be converted to active forms by an in vitro complementation reaction with extracts from certain mutants originated from strain PAO (a pyocin R2 producer). This result indicated the exchangeability of components between R-type pyocins belonging to the different groups.
Production, purification, and characterization of an extracellular chitosanase from Streptomyces
Authors: Price J S , Storck R
Published: January 2020

The synthesis by Streptomyces sp. no. 6 of an extracellular chitosanase was induced by glucosamine. The enzyme was purified to homogeneity by Sephadex G-100, carboxymethyl-cellulose, and diethylaminoethyl-cellulose chromatography. The purified enzyme hydrolyzed chitosan (the beta-1,4-linked polymer of glucosamine) but not chitin nor carboxymethyl-cellulose. The only products of the hydrolysis detectable by paper chromatography were di- and triglucosamine. Sephadex G-100 chromatography and sodium dodecyl sulfate-polyacrylamide gel electrophoresis indicated that the molecular weight of the enzyme was between 29,000 and 26,000. Acid hydrolysates of the enzyme contained no cysteic acid or glucosamine or other carbohydrate. At 25 C, maximum activity was obtained between pH 4.5 and 6.5. The enzymatic hydrolysis of chitosan occurred over a wide range of temperatures and was maximal at 60 C. The rate of the reaction was inhibited by concentrations of soluble chitosan higher than 0.5 g/liter. The apparent Km calculated from a Lineweaver-Burke plot was 0.688 g/liter at pH 5.5. The enzyme prevented spore germination and caused a significant decrease in the turbidity of germinated spore suspensions of the Mucor strains tested. Such a decrease was the result of a partial lysis of the cell wall.
Balanced production of 30S and 50S ribosomal proteins after a nutritional shift-up
Authors: Young R , Dennis P P
Published: January 2020

The synthesis of bulk ribosomal protein (r-protein) after a nutritional shift-up in Escherichia coli B/r was examined. It was found that the molar ratio of the net synthesis rates of 30S and 50S r-protein remains constant during the transition period after the shift-up and equal to the preshift ratio. The implications for the control of ribosome synthesis are discussed.
Properties of the 3-o-methyl-D-glucose transport system in Acholeplasma laidlawii
Authors: Tarshis M A , Bekkouzjin A G , Ladygina V G , Panchenko L F
Published: January 2020

Transport of 3-O-methyl-D-glucose (3-O-MG) by Acholeplasma laidlawii cells was studied. The 3-O-MG transport system appeared to be constitutive in cells grown on 3-O-MG and glucose; the transport process depended on the concentration of substrate used and exhibited typical saturation kinetics, with an apparent Km of 4.6 muM. 3-O-MG was transported as a free carbohydrate and was not metabolized further in the cell. Dependence on pH and temperature and the results of efflux and "counterflow" experiments demonstrated the carrier nature of the transport system. 6-Deoxyglucose and glucose competitively inhibited 3-O-MG transport, whereas maltose inhibited in non-competitively. p-Chloromercuribenzoate, p-chloromercuribenzene sulfonate, N-ethylmaleimide, and iodoacetate inhibited transport of 3-O-MG. Cells were able to accumulate 3-O-MG against a concentration gradient. Some electron transfer inhibitors (rotenone and amytal), arsenate, dicyclohexylcarbodiimide, and proton conductors such as 2,4-dinitrophenol, carbonylcyanide, m-chlorophenylhydrazone, pentachlorophenol, and tetrachlorotrifluoromethylbenzimidazole inhibited this process.
Specific inhibition of phospholipid synthesis in plsA mutants of Escherichia coli
Authors: Ray T K , Cronan J E , Godson G N
Published: January 2020

plsA mutants of Escherichia coli are temperature-sensitive strains which possess two enzymes of abnormal thermolability, sn-glycerol 3-phosphate acyltransferase and adenylate kinase. Phospholipid synthesis is inhibited after shift of plsA mutants to temperatures at the lower end of the nonpermissive temperature range. This inhibition is not due to inactivation of the adenylate kinase activity since nucleic acid (and hence adenosine 5'-triphosphate) synthesis is inhibited only slightly. These results show that in vivo inactivation of the sn-glycerol 3-phosphate acyltransferase can be observed under conditions which allow normal adenylate kinase function.
Deoxyribonucleic acid polymerase II activity in an Escherichia coli mutator strain
Authors: Smith C L , Shizuya H , Moses R E
Published: January 2020

The polB gene encoding deoxyribonucleic acid (DNA) polymerase II has been located close to a mutator gene, mutT1, in Escherichia coli. We find the DNA polymerase II prepared from mutT1, strains to be normal in reaction requirements, heat stability, and ability to remove mismatched bases at termini. Recombinants formed from a mutant defective in DNA polymerase II (polB100) and mutT1 are deficient in polymerase II and have the same mutator phenotype as mutT1. Our linkage analysis indicates that mutT1 and polB100 are not isoallelic.
Morphological analysis of nuclear separation and cell division during the life cycle of Escherichia coli
Authors: Woldringh C L
Published: January 2020

Quantitative electron microscope observations were performed on Escherichia coli B/r after balanced growth with doubling times (tau) of 32 and 60 min. The experimental approach allowed the timing of morphological events during the cell cycle by classifying serially sectioned cells according to length. Visible separation of the nucleoplasm was found to coincide with the time of termination of chromosome replication as predicted by the Cooper-Helmstetter model. The duration of the process of constrictive cell division (10 min) appeared to be independent of the growth rate for tau equals 60 min or less but to increase with increase doubling time in more slowly growing cells. Physiological division, i.e., compartmentalization prior to physical separation of the cells, was only observed to occur in the last minute of the cell cycle. The morphological results indicate that cell elongation continues during the division process in cells with tau equals 32 min, but fails to continue in cells with tau equals 60 min.
Ultrastructural study of polymyxin-resistant isolates of Pseudomonas aeruginosa
Authors: Gilleland H E , Murray R G
Published: January 2020

Upon exposure to 6,000 U of polymyxin B sulfate per ml, cells of the polymyxin-sensitive PAO 1 strain of Pseudomonas aeruginosa displayed in thin sections long projections arising from the outer membrane of the cell wall and extensive cytoplasmic degradation with accumulation of cytoplasmic membrane infoldings. Polymyxin-resistant isolates derived from the PAO 1 strain, however, grew well in the presence of 6,000 U of polymyxin per ml and exhibited none of these effects, having instead the appearance of a typically healthy cell. Freeze-etching of cells of the sensitive strain grown in basal medium without polymyxin revealed a concave cell wall layer studded with numerous particles. Freeze-etching of cells of the resistant isolates grown in basal medium containing 6,000 U of polymyxin per ml revealed a concave cell wall layer (i.e., the outer half of the outer membrane) in which most of these particles were absent. Thus, acquisition of resistance to polymyxin was correlated with an alteration in the architecture of the outer membrane. When the resistant isolates were grown in the basal medium lacking polymyxin and then freeze-etched, the particle distribution in the concave cell wall layer resembled that of the sensitive parent strain. The cells had regained sensitivity to polymyxin upon suspension in medium containing 6,000 U/ml as determined by their failure to grow and by internal damages seen in thin sections. These cells also had acquired increased sensitivity to ethylenediaminetetraacetate, whereas the polymyxin-resistant cells grown in the presence of polymyxin were resistant to lysis by ethylenediaminetetraacetate. The polymyxin-resistant isolates were not stable mutants but instead represented an adaptive response to the presence of polymyxin in the medium.
Substructure and in vitro assembly of the outer, structured layer of Spirillum serpens
Authors: Buckmire F L , Murray R G
Published: January 2020

Electron micrographs of disintegrating units of the outer, structured (HP) layer of Spirillum serpens and of the isolated protein obtained from the HP layer revealed V- and Y-shaped and linear profiles. Interpretation of these forms, influenced by the seemingly trimeric form of the isolated protein and by biochemical data, suggested that the protein subunits were identical and Y shaped. A model is proposed for the assembly of the Y-shaped subunits to form a hexagon composed of two triads (three Y-shaped subunits each). The isolated protein adsorbed to a template of wall fragments (basal layer) to the same degree (over 90%) in high concentrations of Na+, K+ (5 X 10(-2) M), Ca2+, Sr2+, and Mg2+ (10(-2) M). At a lower concentration (4 x 10(-5) M) of the cations there was differential adsorption of the protein. Adsorption to the template in the presence of each cation, followed by dilution, also led to differential release of the protein. The adsorption of the protein to the basal layer was correlated with reassembly of the HP layer on the template. The mechanisms seem to be: (i) an ionic strength-dependent reassembly, which results in an HP layer loosely attached to the template (this layer is easily dissociated by decreasing the ionic strength); and (ii) a cation-specific (Ca2+ or Sr2+, but not Mg2+, Na+, or K+) mechanism independent of ionic strength. In this latter case, the specific cations presumably form strong noncovalent "salt" linkages between triads and the basal layer, enabling stable hexagons and the HP layer to be formed.
Protein-carbohydrate-lipid complex isolated from the cell envelopes of Chlamydia psittaci in alkaline buffer and ethylenediaminetetraacetate
Authors: Narita T , Manire G P
Published: January 2020

Exposure of isolated cell envelopes from purified infectious elementary (EB) of Chlamydia psittaci to sodium carbonate-bicarbonate buffer at pH 10 plus ethylenediaminetetraacetate (EDTA) results in partial solubilization of the total protein. The released materials represent 20% of the dry weight, 16% of the total protein, 40% of the total carbohydrate, and 9% of the total lipid of the cell envelopes. Sucrose density gradient centrifugation, and Sephadex G-200, Sepharose 4B, or diethylaminoethyl-cellulose column chromatography, reveal a protein-carbohydrate-lipid complex of several hundred thousand molecular weight that contains 50% protein. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of the isolated EB cell envelopes reveals two major protein bands, A and B, with estimated molecular masses of approximately 85,000 and 53,000, respectively, both of which also stain for the presence of carbohydrate and lipid. Gel electrophoresis of the protein-carbohydrate-lipid complex reveals two protein bands, C and D, with estimated molecular weights of approximately 17,000 and 13,000, respectively, which contain lipid and a small amount of carbohydrate; bands A and B are not present in the complex. Gel electrophoresis of the cell envelope residues after extraction of the complex with alkali and EDTA shows a single main band, corresponding to the position of band B, which contains protein, carbohydrate, and lipid; band A is completely missing. B and A is believed to be a component of the complex, which is split into two subunits on alkali solubilization.
Effect of cis-platinum(II)diamminodichloride on cell division of Hyphomicrobium and Caulobacter
Authors: Moore R L , Brubaker R R
Published: January 2020

Low concentrations of the radiomimetic agent cis-platinum(II)diamminodichloride (PDD) inhibited cell division in Caulobacter crescentus (0.1 mug/ml) and Hyphomicrobium sp. strain B-522 (1.0 mug/ml) without altering the length of prosthecae. After exposure, cells of C. crescentus appeared as long filaments, whereas only the bud portion of Hyphomicrobium underwent elongation. PDD-treated cells of both species were multinucleated. After the removal of PDD by washing, filaments of C. crescentus fragmented unequally and then normal growth resumed. In Hyphomicrobium (where division involves release of swarmer cells that arise as buds on the distal ends of hyphae), potential septation sites formed in the presence of PDD remained inactive after washing. Reinitiation of cell division in this species was dependent upon the synthesis of new hyphae that could arise from either end of the elongated bud. This finding suggests that the PDD-induced lesion at a given septation site is irreversible and, upon removal of this compound, alternate sites must be synthesized for the subsequent occurrence of cell division.
Genetic co-regulation of galactose and melibiose utilization in Saccharomyces
Authors: Kew O M , Douglas H C
Published: January 2020

The gal3 mutation of Saccharomyces, which is associated with an impairment in the utilization of galactose, has been shown to be pleiotropic, causing similar impairments in the utilization of melibiose and maltose. Milibiose utilization and alpha-galactosidase production are directly controlled by the galactose regulatory elements i, c, and GAL4. The fermentation of maltose and the induction of alpha-glucosidase are regulated independently of the i, c, GAL4 system. The production of alpha-galactosidase and galactose-1-phosphate uridyl transferase is coordinate in galactokinaseless strains. Galactose serves as a nonmetabolized, gratuitous inducer of alpha-galactosidase in strains lacking the genes for one or more of the Leloir pathway enzymes.
Genetic and physical studies of recombinant plasmids formed between an R plasmid of compatibility group FI and sex factor F of HfrH
Authors: Horodniceanu T , Bouanchaud D H
Published: January 2020

Recombinant plasmids between an R plasmid of the FI group (R162/3) and the sex factor F or HfrH were produced after the conjugal transfer of this R plasmid into HfrH. Three types of recombinant plasmids were identified after the mating of HfrH (R162/3) with recA and rec+ recipients. One specimen of each type (pIP218, pIP222, pIP226) was studied in this report. All three recombinant plasmids carry the same genetic information for resistance to antibiotics (CSSuT) retained from R162/3. pIP218 retained all the other properties from F of HfrH: derepression for pilus synthesis, mobilization of the chromosome for the proximally transferred HfrH genes (thr, leu, proA), interference with T7 propagation, and ability to be cured by acridine orange. pIP222 retained from F of HfrH the derepression for pilus synthesis and the same polarity of chromosome transfer (thr, leu, proA), while pIP226 retained the interference with T7 propagation and acridine orange curing. Physical studies revealed that replication control and/or recovery of F and pIP218 as covalent circles of deoxyribonucleic acid are similar, and are different from R162/3. The new plasmids are more likely the result of a substitutive recombination event than a fusion. We propose genetic maps of these recombinant plasmids, showing the unequal participation of the parental plasmids in their formation.
Altered nutritional requirements associated with mutations affecting the structures of ribonucleic acid polymerase in Lactobacillus casei
Authors: Morishita T , Yura T
Published: January 2020

Rifampin-resistant mutants were isolated from Lactobacillus casei S1 and examined for possible simultaneous alteration in nutritional properties. Among the 36 mutants obtained either spontaneously or after mutagenesis with 2-aminopurine, 22 were found to be altered with respect to the specific growth requirements. The majority (20 of 22) of the latter mutants were shown to require L-glutamine in addition to the nutrients required by the parental strain for maximal growth, whereas the remaining mutants had apparently lost the requirement for L-aspartate. Further studies with one of the glutamine-requiring mutants revealed that the rifampin resistance of this strain is due to the resistance of ribonucleic acid polymerase itself and that a single mutation is responsible for both rifampin resistance and the glutamine requirement. These results strongly indicate that a structural alteration of the ribonucleic acid polymerase caused by the rifampin resistance mutation somehow affected glutamine metabolism, possibly through change in selective transcription of the genes involved.
Selection and properties of Escherichia coli mutants defective in the synthesis of cyclopropane fatty acids
Authors: Taylor F , Cronan J E
Published: January 2020

Mutants of Escherichia coli K-12 defective in the synthesis of cyclopropane fatty acids (CFA) have been selected and isolated by a L-[methyl-3H]methionine suicide procedure. Two mutants were isolated. Stationary-phase cultures of both mutants contain less than 0.7% of the CFA content found in the parental strain. The CFA deficiency is attributed to a deficiency of CFA synthetase activity. Extracts of both mutants contain less than 10% of the CFA synthetase activity found in extracts of the parental strain. Experiments in which parental and mutant extracts were mixed indicate that the lack of activity in the mutant strains is not due to an inhibitor of CFA synthetase present in the mutant extracts. We have not yet detected a physiological phenotype for these mutants. These strains grow normally at various temperatures in a variety of media. We have tested survival (colony-forming ability) in response to (i) prolonged incubation in stationary phase, (ii) exposure to drying, and (iii) exposure to detergents, heavy metals, low pH, high salt concentration, and a variety of other environmental conditions. The survival of both mutants is identical to that of the parental strain under all conditions tested. The compositions (excepting the CFA deficiency) and metabolic turnover rates of the phospholipids of both mutant strains are indistinguishable from those of the wild-type strain. The transport of several amino acids also seems normal in these mutants.
Transcriptional control of peptidoglycan precursor synthesis during sporulation in Bacillus sphaericus
Authors: Linnett P E , Tipper D J
Published: January 2020

Synthesis of enzymes functional in the synthesis of nucleotide precursors of peptidoglycan ceases upon initiation of sporulation in Bacillus sphaericus. During sporulation, two periods of synthesis of these enzymes occur. The first starts at spore septum formation and is conincident with forespore engulfment; it involves the synthesis of those enzymes required for making the precursor of vegetative-type peptidoglycan, including L-lysyl ligase but no mesodiaminopimelyl ligase. The second period occurs shortly before the appearance of cortex. It involves the synthesis of diaminopimelyl ligase and the other enzymes needed for making the precursor of cortical peptidoglycan, but not lysyl ligase. Both events are a consequence of derepression at the level of transcription. Neither period of synthesis occurs in asporogenous mutants whose morphological block is at the point of spore septum formation.
Urea-hydrolyzing activity of a T-strain mycoplasma: Ureaplasma urealyticum
Authors: Masover G K , Sawyer J E , Hayflick L
Published: January 2020

The urea-hydrolyzing activity of a T-strain mycoplasma was studied in experiments using whole cells and cell-free enzyme preparations by measuring the release of 14CO2 from [14C]urea. Under the conditions used, the urea concentration optimum is approximately 5.6 X 10(-3) M urea. The activity is soluble and not membrane bound. It is stable at -70 C for several weeks but is more labile at higher temperatures. The pH optimum is between 5.0 and 6.0. The effect of several inhibitors on the activity was tested and revealed similarities, as well as differences, between T-strain mycoplasma urease activity and the urease activity of other organisms and plants.
Arginine decarboxylase from a Pseudomonas species
Authors: Rosenfeld H J , Roberts J
Published: January 2020

An arginine decarboxylase has been isolated from a Pseudomonas species. The enzyme is constitutive and did not appear to be repressed by a variety of carbon sources. After an approximately 40-fold purification, the enzyme appeared more similar in its properties to the Escherichia coli biosynthetic arginine decarboxylase than to the E. coli inducible (biodegradative) enzyme. The Pseudomonas arginine decarboxylase exhibited a pH optimum of 8.1 and an absolute requirement of Mg2+ and pyridoxal phosphate, and was inhibited significantly at lower Mg2+ concentrations by the polyamines putrescine, spermidine, and cadaverine. The Km for L-arginine was about 0.25 mM at pH 8.1 AND 7.2. The enzyme was completely inhibited by p-chloromercuribenzoate. The inhibition was prevented by dithiothreitol, a feature that suggests the involvement of an -SH group. Of a variety of labeled amino acids tested, only L-arginine, but not D-arginine was decarboxylated. D-Arginine was a potent inhibitor of arginine decarboxylase with a Ki of 3.2 muM.
Inactivation of carotenoid-producing and albino strains of Neurospora crassa by visible light, blacklight, and ultraviolet radiation
Authors: Blanc P L , Tuveson R W , Sargent M L
Published: January 2020

Suspensions of Neurospora crassa conidia were inactivated by blacklight (BL) radiation (300 to 425 nm) in the absence of exogenous photosensitizing compounds. Carotenoid-containing wild-type conidia were less sensitive to BL radiation than albino conidia, showing a dose enhancement factor (DEF) of 1.2 for dose levels resulting in less than 10% survival. The same strains were about equally sensitive to shortwave ultraviolet (UV) inactivation. The kinetics of BL inactivation are similar to those of photodynamic inactivation by visible light in the presence of a photosensitizing dye (methylene blue). Only limited inactivation by visible light in the absence of exogenous photosensitizers was observed. BL and UV inactivations are probably caused by different mechanisms since wild-type conidia are only slightly more resistant to BL radiation (DEF = 1.2 at 1.0% survival) than are conidia from a UV-sensitive strain (upr-1, uvs-3). The BL-induced lethal lesions are probably no cyclobutyl pyrimidine dimers since BL-inactivated Haemophilus influenzae transforming deoxyribonucleic acid is not photoreactivated by N. crassa wild-type enzyme extracts, whereas UV-inactivated transforming deoxyribonucleic acid is photoreactivable with this treatment.
Galactosaminogalactan from cell walls of Aspergillus niger
Authors: Bardalaye P C , Nordin J H
Published: January 2020

A new heteropolysaccharide has been isolated by alkaline extraction of hyphal walls of Aspergillus niger NRRL 326 grown in surface culture. Its composition by weight, as determined by paper and gas chromatography and colorimetric analyses, is 70% galactose, 20% galactosamine, 6% glucose, and 1% acetyl. Two independent experiments have been used to ascertain copolymer structure: permeation chromatography in 6 M guanidinium hydrochloride, with controlled-pore glass columns of two fractionation ranges, and nitrous acid deaminative cleavage of galactosaminogalactan followed by reduction of fragments with [3H]borohydride and gel filtration chromatography. One of the tritiated fragments is tentatively identified as the disaccharide derivative galactopyranosyl 2,5-anhydrotalitol, on the basis of chromatographic properties and by kinetics of its acid hydrolysis. Smith degradation, methylation, deamination, and optical rotation studies indicate that the galactosaminogalactan consists of a linear array of hexopyranosyl units joined almost exclusively by alpha-(1 leads to 4) linkages. Hexosaminyl moieties are distributed randomly along the chains, which have an average degree of polymerization of about 100. The possible significance of this macromolecule in hyphal structure is considered.
Regulation of thymidine metabolism in Neurospora crassa
Authors: Griswold W R , Madrid V O , Shaffer P M , Tappen D C , Pugh C S , Abbott M T
Published: January 2020

The utilization of thymidine by Neurospora crassa is initiated by the pyrimidine deoxyribonucleoside 2'-hydroxylase reaction and the consequent formation of thymine and ribose. Thymine must then be oxidatively demethylated by the thymine 7-hydroxylase and uracil-5-carboxylic acid decarboxylase reactions. This article shows that the 2'-hydroxylase reaction can be regulated differently than the oxidative demethylation process and suggests that the 2'-hydroxylase has, in addition to the role of salvaging the pyrimidine ring, the role of providing ribose not only for the utilization of the demethylated pyrimidine but also for other metabolic processes. One way that this difference in regulation was observed was with the uc-1 mutation developed by Williams and Mitchell. The present communication shows that this mutation increases the activities of the 7-hydroxylase and the decarboxylase but has no comparable effect on the 2'-hydroxylase. Qualitatively similar effects on these enzymes were bought about by growth of wild-type Neurospora in media lacking ammonium ion, such as the Westergaard-Mitchell medium. The 2'-hydroxylase and 7-hydroxylase are also differently affected by the carbon dioxide content of the atmosphere above the growing culture and the growth temperature. Studies with inhibitors indicated that the carbon dioxide effect is dependent on protein synthesis.
Urea transport-defective strains of Saccharomyces cerevisiae
Authors: Sumrada R , Gorski M , Cooper T
Published: January 2020

Experiments characterizing the urea active transport system in Saccharomyces cerevisiae indicate that (i) formamide and acetamide are strong competitive inhibitors of urea accumulation, (ii) uptake is maximal at pH 3.3 and is 80% inhibited at pH 6.0, and (iii) adenosine 5'-triphosphate generated by glycolysis in conjunction with formation of an ion gradient is likely the driving force behind urea transport. Mutant strains were isolated that are unable to accumulate urea at external concentrations of 0.25 mM. These strains also exhibit a depressed growth rate on 10 mM urea, indicating existence of a relationship between the active transport and facilitated diffusion modes of urea uptake.
Bacteriophage SP50 as a marker for cell wall growth in Bacillus subtilis
Authors: Archibald A R , Coapes H E
Published: January 2020

When grown under conditions of phosphate limitation, Bacillus subtilis W23 lacked wall teichoic acid and did not adsorb phage SP50. During transition from growth under conditions of phosphate limitation to those of potassium limitation, the bacteria developed an ability to adsorb phage which increased exponentially in relation to their content of wall teichoic acid. During transition in the reverse direction, the bacteria retained near-maximum phage-binding properties until their content of wall teichoic acid had fallen to a fairly low level. These observations suggest that newly incorporated wall material does not immediately appear at the cell surface in a structure to which phage can adsorb. Examination of the location of adsorbed phage particles showed that recently incorporated receptor material appeared at the cell surface first along the length of the cylindrical portion of the cell. The results are consistent with models of wall assembly in which newly synthesized wall material is intercalated at a large number of sites that are distributed along the length of the cell. This newly incorporated material may be located initially at a level underlying the surface of the cell and may become exposed at the surface only during subsequent growth. Incorporation of new material may also proceed rapidly into the developing septa, but new wall material is incorporated into existing polar caps more slowly, or perhaps not at all.
Occurrence of phosphenolpyruvate carboxylase in the extremely thermophilic bacterium Thermus aquaticus
Authors: Bridger G P , Sundaram T K
Published: January 2020

In the extreme thermophile Thermus aquaticus, phosphoenolpyruvate carboxylase catalyzes carbon dioxide fixation on the C3 metabolite phosphoenolpyruvate, producing oxaloacetate. In a moderately thermophilic Bacillus species this function is fulfilled by pyruvate carboyxlase. Like several of its mesophilic counterparts, the Thermus enzyme exhibits a requirement for acetyl coenzyme A.
Expression of the
argA
Gene Carried by a Defective Lambda Bacteriophage of
Escherichia coli
Authors: Leisinger Thomas , Haas Dieter , Kelker Norman
Published: January 2020

Evidence is presented that the increase in specific activity of
N
-acetylglutamate synthase observed upon heat induction of
Escherichia coli
(λ
dargA
) is primarily due to a gene dosage effect.
Kinetics of thymineless death in Escherichia coli 15 as measured by single-cell observations
Authors: Mennigmann H D , Carmona M T
Published: January 2020

Kinetics of thymineless death for Escherichia coli 15 TAU-bar from plating on solid medium were compared with those from direct observations of single cells under a microscope. The latter method did not involve any physical change of the medium. The kinetics obtained for the two methods were identical. This rules out the assumption that in E. coli 15 TAU-bar death from the thymine deprivation is directly associated with the plating procedure.
Compatibility properties of R483, a member of the I plasmid complex
Authors: Datta N , Barth P T
Published: January 2020

R483, an I pilus-determining plasmid previously reported as belonging to a distinct incompatibility group Ibeta, proved to be an atypical Ialpha plasmid; in a growing culture, the degree of inhibition of replication of one Ialpha plasmid by the presence of another was not uniform within the Ialpha group.
Evolution and utility of a Pseudomonas aeruginosa drug resistance factor
Authors: Olsen R H , Hansen J
Published: January 2020

We describe the addition to the Pseudomonas aeruginosa sex factor, FP2, of carbenicillin resistance encoded by the RP1 plasmid. This occurred in a step-wise manner as detected by variations in the characteristics of the FP2-RP1 plasmid aggregate. The addition of the carbenicillin resistance marker to FP2 facilitates estimates of FP2 transfer. Transfer frequencies for the presumed cointegrate plasmid, using carbenicillin selection, approached 10(-1) per donor bacterium. The chromosomal mobilization properties of the derived plasmid, designated pR0271, resembled those of the progenitor plasmid FP2. Plasmid pR0271 was also observed to mobilize a nontransmissible drug resistance plasmid sharing genetic homology at frequencies corresponding to those observed for chromosomal markers proximal to the origin of transfer.