bluuebunny/crossref_metadata_2025 huggingface dataset:
Number of Deoxyribonucleic Acid Uptake Sites in Competent Cells of
Bacillus subtilis
Authors: Singh R. N.
Published: January 2020

Two direct methods are presented for estimating the average number of deoxyribonucleic acid (DNA) uptake sites in competent cells of
Bacillus subtilis
from measurement of
14
C- or
3
H-thymine-labeled DNA uptake by competent culture. Advantage is taken of two facts: (i) effective contact between competent cells and transforming DNA molecules is established within a short time after mixing them together, and (ii) DNA molecules enter the competent
B. subtilis
cells in a linear fashion at a finite speed. From the number of DNA molecules initially attached to competent cells by brief exposure to transforming DNA in the first method or from the rate of DNA uptake by competent culture in the second method, the average number of DNA uptake sites is calculated to be 20 to 53 per competent cell.
Purification and Properties of Streptococcal Competence Factor Isolated from Chemically Defined Medium
Authors: Leonard C. Gomez , Cole Roger M.
Published: January 2020

A procedure for the isolation and purification of competence factor produced in a defined medium by group H streptococci, strain Challis-6, is presented. Partial characterization and chemical analysis of the product are described. The procedure yields competence factor of high purity, as shown by homogeneity in electrofocusing, by electrophoresis in sodium dodecyl sulfate polyacrylamide gels, and by chemical analysis. The data indicate that competence factor is a small, dialyzable, highly basic compound. It is free from lipids, phosphorus, and carbohydrates, and is colorless and thermoresistant. Its biological activity is destroyed by trypsin but not by deoxyribonuclease, ribonuclease, lipase, or lysozyme. Its high isoelectric point of above
p
H 11.0 suggests that competence factor may be a protamine or a polymer of basic amino acids. The possibility that a polyamine may be an integral part of the polypeptide molecule has not been excluded.
Comparative Chemistry of 30
S
Ribosomal Proteins of
Salmonella typhimurium
Authors: Huang Jiunn , Sypherd Paul S.
Published: January 2020

Individual proteins from the 30
S
ribosome of
Salmonella typhimurium
were isolated and compared with their counterparts in
Escherichia coli
. Amino acid composition data reveal either no significant differences, or only minor differences in a few residues between paired proteins. Tryptic peptide fingerprints were used to amplify any possible differences between protein pairs.
Membrane Mutation Associated with Sensitivity to Acriflavine in
Escherichia coli
Authors: Nakamura Hakobu , Suganuma Atsushi
Published: January 2020

The role of plasma membrane on the acriflavine sensitivity of
Escherichia coli
was studied.
14
C-uracil incorporation into ribonucleic acid fraction by spheroplasts was more sensitive to acriflavine in the acriflavine-sensitive strain (genotype
acrA
) than in the acriflavine-resistant (genotype
acrA
+
) strain. There was no difference between two types of cells in the response to osmotic shock, phage sensitivity, and other treatments used to investigate the structure and stability of cell wall. Differences in the electron-microscopic figures between
acrA
and
acrA
+
cells was found in the plasma membrane, surface area just below the membrane, and ribosomal aggregation, when cells were treated with acriflavine. It is concluded that a primary site of acriflavine action is on the plasma membrane, and the
acrA
mutation is mediated by it. On the basis of the present results, it is evident that differences in the acriflavine binding and the sensitivity to phenethyl alcohol and sodium dodecyl sulfate between the
acrA
and
acrA
+
strains, previously reported, are attributable to a structural difference in the plasma membrane between the two strains.
Taxonomy of Aerobic Marine Eubacteria
Authors: Baumann Linda , Baumann Paul , Mandel M. , Allen Richard D.
Published: January 2020

Two hundred and eighteen strains of nonfermentative marine bacteria were submitted to an extensive morphological, physiological, and nutritional characterization. All the strains were gram-negative, straight or curved rods which were motile by means of polar or peritrichous flagella. A wide variety of organic substrates served as sole sources of carbon and energy. The strains differed extensively in their nutritional versatility, being able to utilize from 11 to 85 carbon compounds. Some strains had an extracellular amylase, gelatinase, lipase, or chitinase and were able to utilize
n
-hexadecane and to denitrify. None of the strains had a yellow, cell-associated pigment or a constitutive arginine dihydrolase system, nor were they able to hydrolyze cellulose or agar. The results of the physiological and nutritional characterization were submitted to a numerical analysis which clustered the strains into 22 groups on the basis of phenotypic similarities. The majority of these groups were separable by a large number of unrelated phenotypic traits. Analysis of the moles per cent guanine plus cytosine (GC) content in the deoxyribonucleic acid of representative strains indicated that the peritrichously flagellated groups had a GC content of 53.7 to 67.8 moles%; polarly flagellated strains had a GC content of 30.5 to 64.7 moles%. The peritrichously flagellated groups were assigned to the genus
Alcaligenes
. The polarly flagellated groups, which had a GC content of 43.2 to 48.0 moles%, were placed into a newly created genus,
Alteromonas;
groups which had a GC content of 57.8 to 64.7 moles% were placed into the genus
Pseudomonas;
and the remaining groups were left unassigned. Twelve groups were given the following designations:
Alteromonas communis, A. vaga, A. macleodii, A. marinopraesens, Pseudomonas doudoroffi, P. marina, P. nautica, Alcaligenes pacificus, A. cupidus, A. venustus
, and
A. aestus
. The problems of assigning species of aerobic marine bacteria to genera are discussed.
Effects of Selenium Compounds on Formate Metabolism and Coincidence of Selenium-75 Incorporation and Formic Dehydrogenase Activity in Cell-Free Preparations of
Escherchia coli
Authors: Shum Archie C. , Murphy John C.
Published: January 2020

The effects of selenite, selenocystine, and selenomethionine in a defined growth medium on formic dehydrogenase biosynthesis in aerobically and anaerobically grown
Escherichia coli
have been studied. Sucrose gradient centrifugation of a partially purified enzyme demonstrated a coincidence of
75
Se incorporation and formic dehydrogenase activity.
Specific Repression of Phosphoribosylpyrophosphate Synthetase by Uridine Compounds in
Salmonella typhimurium
Authors: Olszowy Joyce , Switzer R. L.
Published: January 2020

Mutants of
Salmonella typhimurium
with specific pyrimidine requirements were used to demonstrate that only uridine compounds exert repressive control over synthesis of phosphoribosylpyrophosphate synthetase.
Induction of the
ara
Operon of
Escherichia coli
B/r
Authors: Doyle M. Ellin , Brown Candice , Hogg Robert W. , Helling Robert B.
Published: January 2020

The inducer specificity and kinetics of induction of the
ara
operon were examined in
Escherichia coli
B/r. A difference in the kinetics of induction was found between our B/r strains and the K-12 strain previously described by Schleif. The roles of active transport and metabolism of inducer, and of cell density, in induction were studied.
d
-Fucose and β-methyl-
l
-arabinoside were competitive inhibitors of induction. No inducer of the wild-type strain other than
l
-arabinose was found. However, a procedure for selecting mutants with altered inducer affinity or specificity was developed. The properties of one such mutant (inducible by
d
-fucose) are described.
Mode of Action of Oxathiin Systemic Fungicides V. Effect on Electron Transport System of
Ustilago maydis
and
Saccharomyces cerevisiae
Authors: Ulrich J. T. , Mathre D. E.
Published: January 2020

The systemic fungicide carboxin (5,6-dihydro-2-methyl-1,4-oxathiin-3-carboxanilide) at 100 μ
m
inhibited succinate cytochrome
c
reductase in mitochondria from
Ustilago maydis
and
Saccharomyces cerevisiae
. It did not have any effect on reduced nicotinamide adenine dinucleotide (NADH) cytochrome
c
reductase. Succinate coenzyme Q reductase was also inhibited, but NADH coenzyme Q reductase was not. When dichlorophenolindophenol (DCIP) was used as the terminal acceptor of electrons from the oxidation of succinate, carboxin was very effective in inhibiting succinate-DCIP reductase. Carboxin was inhibitory to succinic dehydrogenase assayed with phenazine methosulfate plus DCIP when intact mitochondria were used as the enzyme source but not when solubilized enzyme was used. The main site of action of carboxin, therefore, appears to lie between succinate and coenzyme Q. The dioxide analogue of carboxin was also effective in inhibiting succinate-cytochrome
c
reductase, succinate-coenzyme Q reductase, or succinate-DCIP reductase, whereas the monoxide analogue was less effective in inhibiting these enzymes.
Sporulation and Heat Resistance of
Bacillus stearothermophilus
Spores Produced in Chemically Defined Media
Authors: de Guzman Anselma , Fields M. L. , Humbert R. D. , Kazanas Nuria
Published: January 2020

The effect of amino acids on sporulation is discussed. Heat-resistant spores were produced in a chemically defined medium.
Protein and Ribonucleic Acid Synthesis During the Diploid Life Cycle of
Allomyces arbuscula
Authors: Burke Daniel J. , Seale Thomas W. , McCarthy Brian J.
Published: January 2020

The diploid life cycle of
Allomyces arbuscula
may be divided into four parts: spore induction, germination, vegetative growth, and mitosporangium formation. Spore induction, germination, and mitosporangium formation are insensitive to inhibition of actinomycin D, probably indicating that stable, pre-existing messenger ribonucleic acid (RNA) is responsible for these developmental events. Protein synthesis is necessary during the entire life cycle except for cyst formation. A system for obtaining synchronous germination of mitospores is described. During germination there is a characteristic increase in the rate of synthesis of RNA and protein although none of the other morphogenetic changes occurring during the life cycle are necessarily accompanied by an appreciable change in the rate of macromolecular synthesis.
Multiple Forms of
Pseudomonas multivorans
Glucose-6-Phosphate and 6-Phosphogluconate Dehydrogenases: Differences in Size, Pyridine Nucleotide Specificity, and Susceptibility to Inhibition by Adenosine 5′-Triphosphate
Authors: Lessie T. G. , Wyk J. C. Vander
Published: January 2020

Two major species of glucose-6-phosphate dehydrogenase (EC 1.1.1.49) differing in size, pyridine nucleotide specificity, and susceptibility to inhibition by adenosine 5′-triphosphate (ATP) were detected in extracts of
Pseudomonas multivorans
(which has recently been shown to be synonymous with the species
Pseudomonas cepacia
) ATCC 17616. The large species (molecular weight ca. 230,000) was active with nicotinamide adenine dinucleotide (NAD) or nicotinamide adenine dinucleotide phosphate (NADP) and was markedly inhibited by ATP, which decreased its affinity for glucose-6-phosphate and for pyridine nucleotides. This form of the enzyme exhibited homotropic effects for glucose-6-phosphate. The small species (molecular weight ca. 96,000) was active with NADP but not with NAD, was not inhibited by ATP, and exhibited no homotropic effects for glucose-6-phosphate. Under certain conditions multiplicity of 6-phosphogluconate dehydrogenase (EC 1.1.1.43) activities was also noted. One form of the enzyme (80,000 molecular weight) was active with either NAD or NADP and was inhibited by ATP, which decreased its affinity for 6-phosphogluconate. The other form (120,000 molecular weight) was highly specific for NADP and was not susceptible to inhibition by ATP. Neither form of the enzyme exhibited homotropic effects for 6-phosphogluconate. The possible relationships between the different species of glucose-6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase are discussed.
α-Isopropylmalate Synthase from Yeast: Purification, Kinetic Studies, and Effect of Ligands on Stability
Authors: Ulm E. H. , Böhme R. , Kohlhaw G.
Published: January 2020

α-Isopropylmalate synthase, the first specific enzyme in leucine biosynthesis, was purified approximately 100-fold from extracts of
Saccharomyces
sp. (strain 60615), the most effective step being specific elution with the feedback inhibitor leucine from a hydroxyapatite column. In the early steps of purification, special care was taken to protect the synthase against proteolytic activities. The apparent molecular weight of the enzyme as determined from gel filtration on a calibrated column was 137,000 in the absence and 121,000 in the presence of leucine. Inhibition by leucine was specific and strongly
p
H-dependent, with the leucine concentration necessary for half-maximal inhibition increasing about 10-fold as the
p
H increased from 7.5 to 8.5. Within this
p
H range, catalytic activity remained almost unchanged. The apparent
K
m
values for the two substrates were found to be 16 μ
m
for α-ketoisovalerate and 9 μ
m
for acetyl-coenzyme A. K
+
was required for full activity, the apparent
K
a
value being 2 m
m
. Leucine inhibition was of the mixed type, resulting in decreased
V
max
and increased apparent
K
m
values forboth substrates. Whereas no cooperative effects were observed with either substrate, positive cooperativity was seen with leucine in the presence of saturating substrate concentrations. Leucine and, to a lesser extent, α-ketoisovalerate stabilized the purified enzyme against heat-inactivation. The presence of acetyl-coenzyme A, on the other hand, accelerated the inactivation. In subsequent experiments, coenzyme A was recognized as the actual inactivating ligand, being effective even at lower temperatures and in concentrations which were estimated to be in the range of the enzyme concentration.
Initiation of
Bacillus subtilis
Ribonucleic Acid Polymerase on Deoxyribonucleic Acid from Bacteriophages 2C, φ29, T4, and Lambda
Authors: Pène Jacques J. , Barrow-Carraway Joyce
Published: January 2020

Ribonucleic acid (RNA) synthesis primed by bacteriophage T4 or λ deoxyribonucleic acid (DNA) with
Bacillus subtilis
RNA polymerase is severely inhibited by high ionic strength. In contrast, RNA synthesis on
B. subtilis
bacteriophage 2C, SPO1, or φ29 DNA is only moderately affected under similar conditions. The basis of this inhibition lies in the inability of the enzyme to initiate RNA chains with adenosine triphosphate or guanosine triphosphate (ATP, GTP). Binding to templates and the rate of catalysis in high salt after initiation do not seem to be affected. Incorporation of γ-
32
P-ATP and GTP under a variety of conditions suggests that the specificity of
B. subtilis
RNA polymerase is different from that of the
Escherichia coli
enzyme and that it recognizes few promoters on T4 and λ DNA. Although
B. subtilis
RNA polymerase initiates RNA chains primarily with ATP or GTP, initiations with pyrimidines can occur on DNA molecules in which hydroxymethyluracil replaces thymine. RNA synthesis on denatured DNA does not seem to be inhibited by high ionic strength, and on native T4 or λ DNA the inhibition of initiation at constant ionic strength is inversely but not linearly proportional to the ionic radii of cations used to stabilize bihelical DNA to denaturation.
Genetic Transfer of Episomic Elements Among
Erwinia
Species and Other Enterobacteria: F′
lac
+
Authors: Chatterjee Arun K. , Starr Mortimer P.
Published: January 2020

The episomic element F′
lac
+
was transferred, probably by conjugation, from
Escherichia coli
to Lac
−
strains of
Erwinia herbicola, Erwinia amylovora
, and
Erwinia chrysanthemi
(but not to several other
Erwinia
spp. In preliminary trials). The
lac
genes in the exconjugants of the
Erwinia
spp. showed varying degrees of stability depending on the strain (stable in
E. herbicola
strains Y46 and Y74 and
E. amylovora
strain EA178, but markedly unstable in
E. chrysanthemi
strain EC16). The
lac
genes and the sex factor (F) were eliminated from the exconjugants by treatment with acridine orange, thus suggesting that both
lac
and F are not integrated in the
Erwinia
exconjugants. All of the tested Lac
+
exconjugants of
E. herbicola
strains Y46 and Y74 and
E. amylovora
strain EA178, but not of
E. chrysanthemi
strain EC 16, were sensitive to the F-specific phage M13. The heterogenotes (which harbored F′
lac
+
) of
E. herbicola
strains Y46 and Y74,
E. amylovora
strain EA178, and
E. chrysanthemi
strain EC16 were able to transfer
lac
genes by conjugation to strains of
E. herbicola, E. amylovora, E. chrysanthemi, Escherichia coli
, and
Shigella dysenteriae
. The frequency of such transfer from Lac
+
exconjugants of
Erwinia
spp. was comparable to that achieved by using
E. coli
F′
lac
+
as donors, thus indicating the stability, expression, and restriction-and-modification properties of the sex factor (F) in
Erwinia
spp.
Interrelated Effects of Cold Shock and Osmotic Pressure on the Permeability of the
Escherichia coli
Membrane to Permease Accumulated Substrates
Authors: Leder Irwin G.
Published: January 2020

Permease studies are generally carried out by incubating cells in growth medium with labeled substrate, collecting the cells on microporous membrane filters, and washing them free from extracellular radioactivity with ice-cold medium. Studies of thiomethylgalactoside, valine, and galactose accumulation indicate that in several strains of
Escherichia coli
the bacterial membrane is exquisitely sensitive to isosmotic cold shock. Substrate pools formed at 25 C may suffer almost total loss if the cells are rapidly chilled to approximately 0 C during sampling. In glycerol-grown cells, this rapid efflux of substrate is prevented or minimized if the cells are subjected at the moment of cold shock to a simultaneous hyperosmotic transition. Because of this protective effect, the apparent size of a permease accumulated substrate pool is extremely sensitive to the osmotic composition of the incubation medium and may appear to be increased as much as 10-fold when the osmolarity is reduced from approximately 0.3 to 0.1 osmolar. These differences vanish when sampling and washing are carried out with medium at room temperature. It is suggested that isosmotic cold shock causes crystallization of the liquid-like lipids within the membrane. The hydrophilic channels created in this process would facilitate the rapid efflux of permease accumulated substrates. The imposition of a simultaneous hyperosmotic transition by dehydrating the cell periphery would cause increased lipid interaction, thus preserving the integrity of the cells membrane.
Mutations Affecting Amino Sugar Metabolism in
Escherichia coli
K-12
Authors: Holmes R. P. , Russell R. R. B.
Published: January 2020

The genetic loci determining
N
-acetylglucosamine-6-phosphate deacetylase and glucosamine-6-phosphate deaminase have been located at min 16 on the
Escherichia coli
K-12 genetic map.
Division Site Regulation in a Temperature-Sensitive Mutant of
Bacillus subtilis
Authors: Mendelson Neil H.
Published: January 2020

Division site location was measured in
Bacillus subtilis
clones grown from spores at 30 and 45 C. Regulation of division location is lost in mutant 168ts-151 at 45 C.
Mapping of
rod
Mutants of
Bacillus subtilis
Authors: Karamata D. , McConnell M. , Rogers H. J.
Published: January 2020

Nine class A salt-dependent
rod
mutants were mapped on the
Bacillus subtilis
genome by PBS1-mediated transduction. They are distributed into two small linkage groups designated
rod
B and
rod
C; mutations in
rod
B are over 80% cotransducible with
pheA
and different mutations in
rod
C are 12 to 21% cotransducible with
hisA
. It is established that neither
rod
B nor
rod
C is linked by transformation to the other identified
rod
mutations present in 168-
ts
-200B and 8332
glu
−
. It is hypothesized that salt-dependent mutations are due to enzyme alterations which are corrected by high salt concentrations.
R Factor Elimination During Thymine Starvation: Effects of Inhibition of Protein Synthesis and Readdition of Thymine
Authors: Pinney R. J. , Smith J. T.
Published: January 2020

R factor 1818 is shown to be eliminated from a thymineless strain of
Escherichia coli
J6-2 (R-1818) during thymine starvation. Readdition of thymine to the starved cultures produces a partial recovery in viable count but does not affect the proportion of R
−
cells. The R factor is not cured from exponential- or stationary-phase cultures which are starved of required amino acids as well as thymine, nor from cells which are deprived of thymine in the presence of chloramphenicol. However, in both of these cases, the extent of thymineless death is reduced. It is suggested that protein synthesis is a requirement for R-1818 elimination, and the possible nature of this protein is discussed.
Deoxyribonucleic Acid Base Composition of Species in the Yeast Genus
Kluyveromyces
van der Walt emend. van der Walt
Authors: Martini Alessandro , Phaff Herman J. , Douglass Stephen A.
Published: January 2020

The deoxyribonucleic acid base composition (percent guanine + cytosine [GC]) was determined for 29 strains, representing 18 species of the genus
Kluyveromyces
. It was concluded that on the basis of GC content (47.4%) and other properties
K. veronae
occupies an uncertain position in the genus
Kluyveromyces
. The GC content of the remaining 17 species ranged from 35.3 to 43.4%, and three groups of species were recognized. The GC content of the first ranged from 35.3 to 38.0%; that of the second group from 39.5 to 41.7%; that of the third group from 42.4 to 43.4%. Several species revealed a nearly identical GC content. The GC contents do not correspond in all instances with the five groups of species proposed by van der Walt.
Mode of Action of Phleomycin on
Bacillus subtilis
Authors: Reiter Harvard , Milewskiy Marianne , Kelley Philip
Published: January 2020

Phleomycin appears to act on the cell wall and membrane to induce the release of membrane-associated deoxyribonucleic acid (DNA) and the degradation of the DNA. Degradation occurs in a series of energy-requiring endonuclease and exonuclease reactions. These produce, first, single-strand breaks, then double-strand breaks, and finally almost complete solubilization of the cellular DNA. The in vivo inhibition of DNA synthesis by phleomycin is probably a secondary effect caused by the destruction of template DNA.
Mapping of a
d
-Cycloserine Resistance Locus in
Escherichia coli
K-12
Authors: Russell R. R. B.
Published: January 2020

The mutation conferring first-step resistance to
d
-cycloserine has been located at min 83 on the
Escherichia coli
K-12 genetic map.
Death Through Respiratory Failure of a Fraction of Ultraviolet-Irradiated
Escherichia coli
B/r Cells
Authors: Swenson P. A. , Schenley R. L.
Published: January 2020

Escherichia coli
B/r cells grown on a glycerol-containing medium and ultraviolet (UV)-irradiated to about 0.5% survival respire for about 1 hr and then cease for several hours. The cells that have completed repair and recovery processes begin to divide about 120 min after UV treatment, but this division is completely inhibited in liquid medium by caffeine, which delays repair of the irradiated deoxyribonucleic acid (DNA). When 5-fluorouracil (FU) is used to maintain respiration, the number of cells which form colonies when plated increases about 60-fold within 1 hr after irradiation. At least part of this increase does not involve repair while the cells are in the liquid medium because when caffeine is present there is still a 20-fold increase in colony formation. We conclude that many irradiated cells, although capable of carrying out complete and accurate repair of their DNA, die of respiratory failure; only when continuance of respiration is favored by FU treatment is their colony-forming potential realized. After an early increase, the number of cells able to form colonies in medium that contains FU remains constant while the completion of repair and recovery occurs. After these processes are completed, the number of cells able to form colonies increases slowly, except in the presence of caffeine, presumably because the late increase requires that repair steps take place while the cells are in liquid medium prior to cell division.
Distribution of Alkaline Phosphatase Within the Periplasmic Space of Gram-Negative Bacteria
Authors: MacAlister T. J. , Costerton J. W. , Thompson Linda , Thompson J. , Ingram J. M.
Published: January 2020

Both reaction-product localization and ferritin-coupled antibody studies have shown that alkaline phosphatase is evenly distributed throughout the peri-plasmic space of
Escherichia coli
and a marine pseudomonad. This space is not locally enlarged except in cases where plasmolysis has occurred.
Microbial Assimilation of Hydrocarbons: Cellular Distribution of Fatty Acids
Authors: Makula R. A. , Finnerty W. R.
Published: January 2020

The distribution of cellular fatty acids in defined lipid classes was analyzed in
Micrococcus cerificans
after growth on specified hydrocarbons. Neutral lipid, phospholipid, and cell residue fatty acids were qualitatively and quantitatively determined for
M. cerificans
grown on nutrient broth, tetradecane (C
14
), pentadecane (C
15
), hexadecane (C
16
), and heptadecane (C
17
), respectively. Percentage of total cellular fatty acid localized in defined lipid classes from cells grown on the above growth substrates was (i) neutral lipid—11.8, 1.81, 7.74, 23.1, and 2%; (ii) phospholipid—74.5, 65, 66.43, 62.1, and 86%; (iii) cell residue lipid—13.5, 33.29, 25.82, 14.78, and 11.9%. Phospholipid fatty acid chain length directly reflected the carbon number of the alkane substrate, with 40, 84, 98, and 77% of the fatty acids being 14, 15, 16, and 17 carbons when cells were grown on C
14
, C
15
, C
16
, and C
17
n
-alkanes, respectively. The bound lipids of the cell residue after chloroform-methanol extraction were characterized by 2-hydroxydodecanoic and 2-hydroxytetradecanoic acids plus a broad spectrum of fatty acids ranging from C
10
to C
17
chain length. An increase in total unsaturated fatty acid localized in the phospholipids was noted from cells grown on alkanes greater than 15 carbons long. An extracellular accumulation of free fatty acid (FFA) was demonstrated in hexadecane-grown cultures that was not apparent in non-hydrocarbon-grown cultures. Identification of extracellular FFA demonstrated direct derivation from hexadecane oxidation. Studies supporting inhibition of de novo fatty acid biosynthesis in relationship to extracellular FFA and hexadecane oxidation are described. The ability to alter the fatty acid composition of membrane polar lipids in a predictable manner by the alkane carbon source provides an excellent model system for the investigation of membrane structure-function relationships in
M. cerificans
.
Purine Phosphoribosyltransferases of
Salmonella typhimurium
Authors: Chou Janice Yang , Martin Robert G.
Published: January 2020

Evidence is presented that
Salmonella typhimurium
contains two guanine phosphoribosyltransferases.
Nutritional Requirements of
Acinetobacter
Strains Isolated from Soil, Water, and Sewage
Authors: Warskow Alice L. , Juni Elliot
Published: January 2020

One hundred five strains of
Acinetobacter
were isolated from water, soil, and sewage on nonselective complex media, and their nutritional properties were studied. Only one of these strains requires growth factors in order to grow in a mineral medium containing a single carbon source.
Genetic Separation of Hypoxanthine and Guanine-Xanthine Phosphoribosyltransferase Activities by Deletion Mutations in
Salmonella typhimurium
Authors: Gots Joseph S. , Benson Charles E. , Shumas Susan R.
Published: January 2020

Certain
proAB
deletion mutants of
Salmonella typhimurium
were found to be simultaneously deleted in a gene required for the utilization of guanine and xanthine (designated
gxu
). These mutants were resistant to 8-azaguanine and when carrying an additional
pur
mutation were unable to use guanine or xanthine as a purine source. The defect was correlated with deficiencies in the uptake and phosphoribosyltransferase activities for guanine and xanthine. Hypoxanthine and adenine activities were unaltered. The deficiency was restored to normal by transduction to
pro
+
and in F′ merodiploids.
Translation of Synthetic and Endogenous Messenger Ribonucleic Acid In Vitro by Ribosomes and Polyribosomes from
Clostridium pasteurianum
Authors: Himes Richard H. , Stallcup Michael R. , Rabinowitz Jesse C.
Published: January 2020

Ribosomes and polyribosomes from
Clostridium pasteurianum
were isolated and their activities were compared with those of ribosomes from
Escherichia coli
in protein synthesis in vitro.
C. pasteurianum
ribosomes exhibited a high level of activity due to endogenous messenger ribonucleic acid (RNA). For translation of polyuridylic acid [poly(U)],
C. pasteurianum
ribosomes required a higher concentration of Mg
2+
and a much higher level of poly(U) than did
E. coli
ribosomes. Phage f2 RNA added to the system with
C. pasteurianum
ribosomes gave no significant stimulation of protein synthesis in a homologous system or with
E. coli
initiation factors. The 30
S
and 50
S
subunits prepared from
C. pasteurianum
ribosomes reassociated less readily than subunits from
E. coli
. The ability of the
C. pasteurianum
subunits to reassociated was found to be dependent upon the presence of a reducing agent during preparation and during analysis of the reassociation products. In heterologous combinations,
E. coli
30
S
subunits associated readily with
C. pasteurianum
50
S
subunits to form 70
S
particles, but
C. pasteurianum
30
S
subunits and
E. coli
50
S
subunits did not associate. In poly(U) translation,
E. coli
30
S
subunits were active in combination with 50
S
subunits from either
E. coli
or
C. pasteurianum
, but
C. pasteurianum
30
S
subunits were not active in combination with either type of 50
S
subunits. Polyribosomes prepared from
C. pasteurianum
were very active in protein synthesis, and well-defined ribosomal aggregates as large as heptamers could be seen on sucrose gradients. An attempt was made to demonstrate synthesis in vitro of ferredoxin.
Studies of the Acetate Kinase-Phosphotransacetylase and the Butanediol-Forming Systems in
Aerobacter aerogenes
Authors: Brown T. D. K. , Pereira C. R. S. , Størmer F. C.
Published: January 2020

Mutants of
Aerobacter aerogenes
devoid of acetate kinase and phosphotransacetylase activities were isolated by selection for resistance to fluoroacetate on lactate medium. The mutants were used to study the role of the acetate kinase-phosphotransacetylase system in growth on acetate and glucose. Acetate kinase-negative and phosphotransacetylase-negative mutants were unable to grow on acetate minimal medium. Their growth rates on glucose minimal medium were identical with that of the parent strain under aerobic conditions, but lower growth rates were observed in the mutant strains during anaerobic growth on glucose medium. The mutants were unable to incorporate [
2
-
14
C
]-acetate rapidly while growing on glycerol. Variations in acetate kinase and phosphotransacetylase levels during growth on glucose were studied. The specific activities of the enzymes increased approximately fivefold during aerobic growth on glucose in batch culture. The enzyme levels were also studied during anaerobic growth on glucose at constant
p
H (
p
H 5.8 and 7.0). Smaller increases in specific activities were found under these conditions. The role of acetate in the induction of the diacetyl (acetoin) reductase was investigated using a mutant deficient in both acetate kinase and phosphotransacetylase. The effect of
p
H on the induction of this enzyme during growth on glucose under anaerobic conditions was tested. The data support the idea that free acetic acid is the inducer for the enzymes of the butanediol-forming pathway in
A. aerogenes.
Saliva-Induced Aggregation of Oral Streptococci
Authors: Kashket S. , Donaldson C. G.
Published: January 2020

Cells of several species of oral microorganisms have been shown, in earlier studies, to be aggregated by saliva. In the present study some of the basic properties of the aggregation system are examined. The observation is made that the saliva-induced aggregates of
Streptococcus sanguis
and
S. mitis
can be dissociated to stable particles which consist of about 100 cells and have a median diameter of about 4.5 μm. It is proposed that these are subunits, or core aggregates, of the large primary aggregates. Counts of the core aggregates can be taken as a precise and accurate measure of aggregation. Experiments based on this procedure show that the aggregation of
S. sanguis
is maximal at 10 C and at 1 meq of Ca
2+
ions per liter and is not affected by a change in
p
H between 3.9 and 8.7 or by a change in the phase of growth of the microorganisms. Core aggregates diminish in number with prolonged incubation, suggesting that the aggregating factors break down with time. Formalinized cells yield stable aggregates. However, with Formalinized cell aggregation is maximal between 20 and 30 C and proceeds in the absence of calcium ions. Evidence is presented that whole saliva contains separate aggregating factors for
S. sanguis
and
S. mitis
. The factors differ in their affinity for intact cells and for hydroxyapatite and differ in their stability to dialysis. These findings suggest that many different aggregating factors exist in saliva, each of which may be capable of interacting with cells of one or several bacterial species.
R Factor-Controlled Restriction and Modification of Deoxyribonucleic Acid: Restriction Mutants
Authors: Yoshimori Robert , Roulland-Dussoix Daisy , Boyer Herbert W.
Published: January 2020

Restriction mutants of two different R factor-controlled host specificities (RI and RII) were isolated. All of the restriction mutants examined had a normal modification phenotype. No complementation was observed between the RI and RII host specificities. It is concluded that for each host specificity no protein subunit is shared by the restriction endonuclease and modification methylase.
Improvement of the Specificity of an Antiserum to β-Lactamase by Absorption with a Mutant Which Does Not Produce the Enzyme
Authors: Ross G. W. , Boulton M. G.
Published: January 2020

Absorption of antiserum to crude β-lactamase with a mutant strain lacking the enzyme produced specific β-lactamase antiserum.
Effect of Alanine, Leucine, and Fructose on Lysyl-Transfer Ribonucleic Acid Ligase Activity in a Mutant of
Escherichia coli
K-12
Authors: Hirshfield Irvin N. , Buklad Naomi E.
Published: January 2020

A mutant of
Escherichia coli
K-12 was examined which has growth medium-dependent lysyl-transfer ribonucleic acid (tRNA) ligase activity. In minimal medium or 0.5% yeast extract, the activity of the enzyme in the mutant strain was 5 to 10% of wild type. However, when the mutant was grown in a highly enriched medium, such as AC broth (Difco), the activity of the mutant ligase increased 10- to 20-fold. We found that the supplementation of 0.5% yeast extract by
l
-alanine plus
d
-fructose replaces the need for the highly enriched medium. Fructose plus
l
-leucine and fructose plus
l
-α-amino-
n
-butyric acid were also stimulatory, but not as effective as fructose and alanine. With minimal medium, a combination of carbohydrate (fructose or glucose) plus alanine and leucine was required to replace the enriched medium. The most effective combination was fructose, glucose, alanine, and leucine. Lysyl-tRNA ligase was stimulated 1.5 to 2-fold in the wild-type strain or Hfr H (Hayes) by fructose plus alanine when these strains were cultured in 0.5% yeast extract. Experiments employing the combined technique of density labeling with D
2
O and isopycnic centrifugation in cesium chloride indicated that the increased activity of lysyl-tRNA ligase observed in AC broth or in the presence of fructose, glucose, alanine, and leucine is due to the synthesis of new enzyme.
Effect of Reversible Inhibition of Deoxyribonucleic Acid Synthesis on the Yeast Cell Cycle
Authors: Slater Martin L.
Published: January 2020

Hydroxyurea (HU) preferentially inhibited deoxyribonucleic acid (DNA) replication and division in
Saccharomyces cerevisiae
. Growth, ribonucleic acid synthesis, and protein synthesis were less sensitive to this drug. Upon addition of HU, cells underwent one cycle of budding and the nuclei migrated into the necks between the mother cells and buds. Neither the nucleus nor the cells divided. Removal of HU allowed immediate resumption of DNA synthesis. Nuclear division, budding, and cell division occurred 1.5, 2, and 4 hr, respectively, after HU was removed. If protein synthesis was blocked at the time HU was removed, budding and cell division did not occur. These results were interpreted to indicate that HU prevents accumulation of the potential to initiate a new cell cycle.
Survival of
Arthrobacter crystallopoietes
During Prolonged Periods of Extreme Desiccation
Authors: Boylen Charles W.
Published: January 2020

Cells of
Arthrobacter crystallopoietes
mixed in sand and air-dried have survived for up to 6 months after an initial period in which approximately half the cells lost their viability. Comparative survival curves have been obtained from inoculated sands maintained under CaSO
4
or P
2
O
5
. Selections for more desiccation-resistant progeny capable of surviving the initial period were unsuccessful. Both the coccoid and rod-shaped forms are equally resistant to several months of desiccation. Desiccated spherical cells converted 0.0005% of their cell carbon to carbon dioxide per hr, which corresponds to a half-life for self-consumption of approximately 12 years.
Ultrastructural Alterations Associated with the Growth of Resistant
Pseudomonas aeruginosa
in the Presence of Benzalkonium Chloride
Authors: Hoffmann Hans-Peter , Geftic Sam G. , Gelzer Justus , Heymann Hans , Adair Frank W.
Published: January 2020

Cells of
Pseudomonas aeruginosa
resistant to benzalkonium chloride (BC) underwent unique ultrastructural reorganizations when they were grown in the presence of 1 mg of BC/ml. The resistant cells usually contained a single, centrally positioned pseudovacuole. The pseudovacuole was surrounded by a diffuse substance that spread irregularly throughout the cytoplasm. The presence of the pseudovacuole seemed to cause a physical compartmentalization of the cytoplasm into random pockets of ribosomes and nuclear material. Contained within the pseudovacuole was a horseshoe-shaped, electron-dense body which was bounded by a trilaminar membrane 5.2 nm in width. These bodies averaged 77 nm when measured through the long axis. The surfaces of resistant cells were covered by an additional layer not found in sensitive cells. Thin sections of sensitive cells which had been treated with 1 mg of BC/ml showed little or no lysis. The cytoplasm appeared to be deeply stained and coagulated. Ribosomes were no longer distinctly visible. Although the cell wall remained intact, the cell membrane was dissolved and fragmented. BC-grown resistant cells could not be successfully stained by standard techniques; however, details were demonstrated with the aid of a combination of 1.5% glutaraldehyde, 1% osmium tetroxide, and 1% phosphotungstic acid prepared in 0.1
m
sodium dimethylarsonate buffer (
p
H 6.8).
Synthesis and Structure of
Caulobacter crescentus
Flagella
Authors: Shapiro Lucille , Maizel J. V.
Published: January 2020

During the normal cell cycle of
Caulobacter crescentus
, flagella are released into the culture fluid as swarmer cells differentiate into stalked cells. The released flagellum is composed of a filament, hook, and rod. The molecular weight of purified flagellin (subunit of flagella filament) is 25,000 as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The formation of a flagellum opposite the stalk has been observed by microscope during the differentiation of a stalked cell in preparation for cell division. By pulsing synchronized cultures with
14
C-amino acids it has been demonstrated that the synthesis of flagellin occurs approximately 30 to 40 min before cell division. Flagellin, therefore, is synthesized at a discrete time in the cell cycle and is assembled into flagella at a specific site on the cell. A mutant of
C. crescentus
that fails to synthesize flagellin has been isolated.
Isolation of Covalently Closed Circular Deoxyribonucleic Acid from Bacteria Which Produce Exocellular Nuclease
Authors: Timmis Kenneth , Winkler Ulrich
Published: January 2020

Reproducible yields of covalently closed circular (plasmid) deoxyribonucleic acid were obtained from mutants defective for extracellular nuclease but not from the corresponding wild-type strain of
Serratia marcescens
Abnormal Septation and Inhibition of Sporulation by Accumulation of
l
-α-Glycerophosphate in
Bacillus subtilis
Mutants
Authors: Oh Yong K. , Freese Elisabeth B. , Freese Ernst
Published: January 2020

Accumulation of
l
-α-glycerophosphate, in cells of
Bacillus subtilis
mutants lacking the nicotinamide adenine dinucleotide-independent glycerophosphate dehydrogenase activity, suppresses both growth and sporulation. After growth has stopped, the cells slowly develop one and later more asymmetric septa that are thicker than normal prespore septa and apparently contain too much cell wall material to allow further membrane development into forespores or spores.
l
-Malate prevents accumulation of glycerophosphate and restores sporulation of the mutant. Glucose or gluconate cannot resotre sporulation, because they still effect glycerophosphate accumulation via de novo synthesis. If that accumulation is blocked in a double mutant, which is unable to make glycerophosphate from or to metabolize it into Embden-Meyerhof compounds, then nonsuppressing amounts of glucose or gluconate can restore sporulation.
Ascospore Wall Development in
Saccharomyces cerevisiae
Authors: Beckett A. , Illingworth R. F. , Rose A. H.
Published: January 2020

Ascospore delimitation in
Saccharomyces cerevisiae
is initiated by a pair of unit membranes between which the spore wall is subsequently laid down.
Properties of
d
-Arabinose Isomerase Purified from Two Strains of
Escherichia coli
Authors: Boulter James R. , Gielow William O.
Published: January 2020

d
-Arabinose isomerase (EC 5.3.1.3) has been isolated from
l
-fucose-induced cultures of
Escherichia coli
K-12 and
d
-arabinose-induced cultures of
E. coli
B/r. Both enzymes were homogeneous in an ultracentrifuge and migrated as single bands upon disc electrophoresis in acrylamide gels. The
s
20,w
was 14.5 × 10
−13
sec for the
E. coli
K-12 enzyme and 14.3 × 10
−13
sec for the
E. coli
B/r enzyme. The molecular weight, determined by high-speed sedimentation equilibrium, was 3.55 ± 0.06 × 10
5
for the
E. coli
K-12 enzyme and 3.42 ± 0.04 × 10
5
for the enzyme isolated from
E. coli
B/r. Both enzyme preparations were active wth
l
-fucose or
d
-arabinose as substrates and showed no activity on any of the other aldopentoses or aldohexoses tested. With the
E. coli
K-12 enzyme, the
K
m
was 2.8 × 10
−1
m
for
d
-arabinose and 4.5 × 10
−2
m
for
l
-fucose; with the
E. coli
B/r enzyme, the
K
m
was 1.7 × 10
−1
m
for
d
-arabinose and 4.2 × 10
−2
m
for
l
-fucose. Both enzymes were inhibited by several of the polyalcohols tested, ribitol,
l
-arabitol, and dulcitol being the strongest. Both enzymes exhibited a broad plateau of optimal catalytic activity in the alkaline range. Both enzymes were stimulated by the presence of Mn
2+
or Co
2+
ions, but were strongly inhibited by the presence of Cd
2+
ions. Both enzymes were precipitated by antisera prepared against either enzyme preparation. The amino acid composition for both proteins has been determined; a striking similarity has been detected. Both enzymes could be dissociated, by protonation at
p
H 2 or by dialysis against buffer containing 8
m
urea, into subunits that were homogeneous in an ultracentrifuge and migrated as single bands on disc electrophoresis in acrylamide gels containing urea. The molecular weight of the subunit, determined by high-speed sedimentation equilibrium, was 9.09 ± 0.2 × 10
4
for the enzyme from
E. coli
K-12 and 8.46 ± 0.1 × 10
4
for the enzyme from
E. coli
B/r. On the basis of biophysical studies, both isomerases appear to be oligomeric proteins consisting of four identical subunits.
Ribonucleic Acid and Protein Synthesis During Germination of
Myxococcus xanthus
Myxospores
Authors: Juengst Fredrick W. , Dworkin Martin
Published: January 2020

Ribonucleic acid (RNA) and protein synthesis during myxospore germination were examined. When RNA synthesis was inhibited more than 90% by either actinomycin D (Act D) or rifampin, germination was prevented. The data were consistent with the interpretation that rifampin did not interfere with protein synthesis in any way other than by inhibition of messenger RNA formation. Act D concentrations as high as 20 μg/ml did not totally inhibit RNA synthesis. In the presence of 8 μg of Act D/ml, germinating myxospores synthesized transfer RNA, 16
S
RNA, and 23
S
RNA. Evidence was presented which indicated that messenger RNA was also synthesized early in the germination period both in the presence and absence of 8 μg of Act D/ml. One explanation for the escape synthesis of RNA in germinating myxospores is that Act D exerts a differential effect on the transcription of larger versus smaller cistrons, the latter having a lower probability of binding Act D. We have found that in the presence of 8 μg of Act D/ml, escape RNA synthesis in myxospores was 25% for 23
S
RNA, 55% for 16
S
RNA, and more than 90% for 4
S
RNA. We have shown that germination of myxospores requires both RNA and protein synthesis during the first 25 to 35 min in germination medium. This finding does not support the earlier suggestion by Ramsey and Dworkin that a stable germination messenger RNA is required for germination of the myxospores of
Myxococcus xanthus
.
Rapid Mapping of Conditional and Auxotrophic Mutations in
Escherichia coli
K-12
Authors: Low Brooks
Published: January 2020

The approximate genetic map locations of auxotrophic and conditional lethal mutations of
Escherichia coli
can be rapidly determined with replica plating techniques. A set of patches of 15 streptomycin-sensitive (Str
S
) Hfr strains with points of origin distributed around the map is replica plated onto a recombinant-selective plate with a lawn of Str
R
cells which carry an unmapped mutation. The map interval defined by the Hfr points of origin which are closest to the mutant locus is seen by the presence or absence of heavy patches of recombinants produced by transfer of early wild-type genes from the Hfrs. An alternative method is to replicate patches of different mutant strains (100 per plate) onto Hfr lawns; in this case more than 1,000 different mutants can be mapped in a single experiment in a few days. In this way, many types of mutations with similar phenotypes can be grouped as to approximate location on the genetic map. For ordering mutations within groups, the same replica plating methods can be used to cross F-prime derivatives of mutants with other mutants of the same group. Relative merits of these and other mapping methods of
E. coli
are discussed.
Regulation of Nigeran Accumulation by
Aspergillus aculeatus
Authors: Gold Michael H. , Mitzel Duane L. , Segel Irwin H.
Published: January 2020

Nigeran (mycodextran), an unbranched glucan consisting of alternating α,1–4 and α,1–3 linkages, is accumulated intracellularly by
Aspergillus aculeatus
, under conditions of nitrogen limitation and low
p
H (optimum
p
H 5.0). Both conditions are necessary. Nigeran is synthesized de novo from exogenous glucose and accounts for about 20% of the glucose transported by the mycelium. The polymer is diluted out but not degraded when the mycelium is transferred to fresh medium containing NH
4
+
. Cycloheximide prevents development of the nigeran biosynthetic system. The addition of substrate levels of NH
4
+
to nigeran-accumulating mycelium immediately suppresses further nigeran buildup, presumably by diverting glucose to the biosynthesis of amino acids, nucleotides, etc.