bluuebunny/crossref_metadata_2025 huggingface dataset:
γ-Aminobutyric Acid as a Required Germinant for Mutant Spores of
Bacillus megaterium
Authors: Foerster Harold F.
Published: January 2020

Germinated spores of
Bacillus megaterium
QM B1551 were irradiated with ultraviolet light, and spore-forming survivors were screened for germination requirements. Spore strains which failed to germinate in a variety of defined solutions germinative for spores of the parent strain were obtained. Mutant spores germinated readily in solutions containing yeast extract or one of numerous complex preparations. γ-Aminobutyric acid, obtained from yeast extract by column chromatography, was shown to be required for germination by the mutant spores. γ-Aminobutyric acid and
l
-alanine at final concentrations of 1 m
m
each, in solutions of KI (40 m
m
), equaled the potency of yeast extract (1 mg/ml) in the germination of the mutant spores. One of several other amino acids could be substituted, though less effectively, for
l
-alanine. α-Aminobutyric acid, β-aminobutyric acid, β-alanine, and 5-aminovaleric acid were ineffective substitutes for γ-aminobutyric acid in mutant spore germination.
Evidence for Distinct Kynureninase and Hydroxykynureninase Activities in
Neurospora crassa
Authors: Gaertner F. H. , Cole K. W. , Welch G. R.
Published: January 2020

Previous studies have indicated that a single enzyme, “kynureninase,” catalyzes the reactions of
l
-kynurenine to anthranilate and
l
-3-hydroxykynurenine to 3-hydroxyanthranilate in
Neurospora crassa
and in other organisms. The present report describes separate enzymes which catalyze these reactions in
N. crassa
. The first, a
kynureninase
, preferentially catalyzes kynurenine to anthranilate and is induced over 400-fold by tryptophan or a catabolite of tryptophan. The second, a
hydroxykynureninase
, is constitutive or noninducible by tryptophan and preferentially catalyzes
l
-3-hydroxykynurenine to 3-hydroxyanthranilate. The physiological significance of these enzymes may be inferred from the facts that (i) the noninducible enzyme hydroxykynureninase appears to be the main enzyme present in uninduced cells that is capable of catalyzing
l
-3-hydroxykynurenine to 3-hydroxyanthranilate for the indispensible synthesis of nicotinamide adenine dinucleotide, and (ii) the inducible enzyme kynureninase is induced by tryptophan to a concentration far in excess of that needed to meet the requirements of the cells for nicotinamide adenine dinucleotide, resulting in the excretion of anthranilate into the medium.
Oxidative Phosphorylation in Fractionated Bacterial Systems: Effect of Chloramphenicol
Authors: Cavari Ben-Zion , Kalra Vijay K. , Brodie Arnold F.
Published: January 2020

Chloramphenicol was found to have a direct effect on the respiratory chain of
Mycobacterium phlei
cells grown in the presence of this drug. Analysis of the respiratory chain components revealed that the presence of chloramphenicol during growth resulted in a partial inhibition in the synthesis of the cytochromes. However, a stimulation in oxidative phosphorylation was observed with the cell-free extract of cells grown in the presence of chloramphenicol. The oxidation of succinate was found to be stimulated 20 to 130%, depending on the particular extract, whereas the oxidation of reduced nicotinamide adenine dinucleotide (NADH) was found to be similar to that of extracts obtained from cells grown in the absence of the drug. Of particular interest was the finding that the cell-free extract of cells grown in the presence of the drug exhibited an increased level of phosphorylation (17 to 100%) when NADH was used as the electron donor. Chloramphenicol appears to affect a component of the respiratory chain between the flavoprotein and cytochrome
c
. Fractionation of the electron transport particles revealed an increased level of cytochrome
b
in the fractions which exhibited a stimulation in oxidative phosphorylation.
Equilibrium Constant for Conversion of Pyruvate to Acetyl Phosphate and Formate
Authors: Tanaka Nobumasa , Johnson Marvin J.
Published: January 2020

Preparations of pyruvate formate-lyase were made from
Escherichia coli
cells. Net reversal of the “phosphoroclastic split” of pyruvate was readily demonstrated with these preparations. Incubation of acetyl phosphate with formate resulted in the accumulation of pyruvate in concentrations up to 0.5 m
m
. Catalytic amounts of coenzyme A were essential. Pyruvate was also readily formed from acetyl coenzyme A and formate. The equilibrium constant of the reaction (pyruvate
−
+ HPO
4
2−
→ acetyl phosphate
2−
+ formate
−
) has been determined to be about 23 at 37 C.
Anaerobic
l
-α-Glycerophosphate Dehydrogenase of
Escherichia coli:
Its Genetic Locus and Its Physiological Role
Authors: Kistler W. S. , Lin E. C. C.
Published: January 2020

In mutant cells of
Escherichia coli
missing the particulate
l
-α-glycerophosphate (
l
-α-GP) dehydrogenase necessary for aerobic growth on glycerol or
l
-αGP, a soluble, flavine-dependent
l
-α-GP dehydrogenase supports normal anaerobic growth rates on either of the two substrates with fumarate or nitrate as exogenous hydrogen acceptor. In an experiment in which glycerol served as the carbon source and nitrate as the acceptor, the growth of such a mutant was arrested upon the admission of air, whereas the growth of wild-type cells continued smoothly. Mutant cells lacking the soluble
l
-α-GP dehydrogenase, but possessing the particulate enzyme, can grow at normal rates aerobically on glycerol and
l
-α-GP or anaerobically on these compounds with nitrate, but not fumarate, as the hydrogen acceptor. Double mutants lacking both of the dehydrogenases fail to show significant growth on either glycerol or
l
-α-GP under any condition. Mutations affecting the anaerobic dehydrogenase (
glpA
locus) are situated at about minute 43 of the Taylor map, just clockwise beyond
glpT
, and show cotransduction with
purF
(1.5%),
glpT
(91%), and
nalA
(50%). The anaerobic dehydrogenase is a member of the
glp
regulon as judged by its inducibility by
l
-α-GP and by its constitutive formation in strains of
glpR
c
genotype. The level of the anaerobic dehydrogenase is about the same in cells grown either aerobically or anaerobically with nitrate serving as a terminal hydrogen acceptor. With fumarate as terminal acceptor, the level is elevated several fold.
Influence of Carboxylic Acids on the Stereospecific Nicotinamide Adenine Dinucleotide-Dependent and Nicotinamide Adenine Dinucleotide-Independent Lactate Dehydrogenases ofLeuconostoc mesenteroides
Authors: Doelle Horst W.
Published: January 2020

Leuconostoc mesenteroidesincreased its lactic acid production from glucose threefold when malic acid was added to the culture. This increase resulted also in a reduction of the ratio ofd-lactic acid tol-lactic acid (31.5 to 1.23). Addition of malic acid increased 6.5-fold the specific activity of nicotinamide adenine dinucleotide (NAD)-linkedl-lactate dehydrogenase and increased 3.2-fold that of NAD-linkedd-lactate dehydrogenase. The Michaelis constant (Km) for NAD of the NAD-linkedl-lactate dehydrogenase increased with the addition of malate, but no change was observed in theKmvalues for the respectived-enzyme. The effect of carboxylic acids on the NAD-linkedl-lactate dehydrogenase activities was tested by using partially purified enzyme preparations from cells grown with glucose alone and from cells grown with glucose plus malate. Malate stimulated thel-enzyme and inhibited thed-lactate dehydrogenase. The NAD-linkedl-lactate dehydrogenase exhibited the same activity bands on polyacrylamide gel electrophoresis whether the cell-free preparation originated from cells grown on glucose plus malate or on glucose as the sole carbon source. The NAD-linkedd-lactate dehydrogenase, however, exhibited a different pattern of electrophoretic mobility, depending upon the source of origin of the cell-free preparation. The results suggest that malate has a stimulatory effect on the synthesis of both enzymes and may result in rearrangement of the protein structure of thed-lactate dehydrogenase. This rearrangement apparently makes thed-enzyme more susceptible to inhibition of catalytic activity. Thel-lactate dehydrogenase, however, is stimulated not only in its synthesis but also in its activity. It is proposed that these effects are responsible for the regulation of lactic acid production.
Genetic Analysis of an
Escherichia coli
Syndrome
Authors: Lennette Evelyne T. , Apirion David
Published: January 2020

A mutant strain of
Escherichia coli
that fails to recover from prolonged (72 hr) starvation also fails to grow at 43 C. Extracts of this mutant strain show an increased ribonuclease II activity as compared to extracts of the parental strain, and stable ribonucleic acid is degraded to a larger extent in this strain during starvation. Ts
+
transductants and revertants were tested for all the above-mentioned phenotypes. All the Ts
+
transductants and revertants tested behaved like the Ts
+
parental strain, which suggests that all the observed phenotypes are caused by a single
sts
(starvation-temperature sensitivity) mutation. The reversion rate from
sts
−
to
sts
+
is rather low but is within the range of reversion rates for other single-site mutations. Three-point transduction crosses located this
sts
mutation between the
ilv
and
rbs
genes. The properties of
sts
+
/
sts
−
merozygotes suggested that the Ts
−
phenotype of this mutation is recessive.
Growth-Linked Instability of a Mutant Valyl-Transfer Ribonucleic Acid Synthetase inEscherichia coli
Authors: Anderson James J. , Neidhardt Frederick C.
Published: January 2020

The valyl-transfer ribonucleic acid (tRNA) synthetase ofEscherichia colistrain NP2907, previously described as having an elevatedKmfor adenosine triphosphate and reduced stability in vitro compared to the wild type, was found to be conditionally thermolabile in vivo. The rate of inactivation of this enzyme at a particular temperature appears to be coordinated with the rate of growth; at 40 C this coordination results in equal rates of synthesis and destruction over a wide range of growth rates. In vitro studies showed that conditions favoring maintenance of the valyl-tRNA synthetase-valyl adenylate complex conferred complete protection against inactivation at 40 C, whereas the further addition of uncharged tRNA caused rapid, irreversible decay. We propose that the rate of inactivation of this mutant valyl-tRNA synthetase in vivo is a function of the ratio of deacylated to acylated tRNAvaland that this ratio is a function of growth rate. The event which renders the valyl-tRNA synthetase susceptible to inactivation is likely to be the normal breakdown of the valyl-tRNA synthetase–valyl-adenylate complex during a cycle of aminoacylation of tRNAval.
Transport of
S
-Adenosylmethionine in
Saccharomyces cerevisiae
Authors: Murphy J. T. , Spence K. D.
Published: January 2020

The properties of a specific system for the transport of
S
-adenosylmethionine in yeast are described. The process was
p
H-, temperature-, and energy-dependent, and showed saturation kinetics. The
K
m
for the system was 3.3 × 10
−6
m
. Of the
S
-adenosylmethionine moieties tested, only
S
-adenosylhomocysteine competitively inhibited the uptake of the adenosylsulfonium compound. Adenine, adenosine, methionine, homocysteine, and the sulfonium compound
S
-methylmethionine were without effect. The analogue
S
-adenosylethionine showed competitive inhibition. Under conditions of inhibition of protein synthesis by cycloheximide or methionine starvation, permease activity was stable. The mutant
sam-p3
apparently was able to transport
S
-adenosylmethionine only by diffusion. Uptake by diploids containing this mutation was directly proportional to the gene dose.
Isolating Tryptophan Regulatory Mutants inEscherichia coliby Using atrp-lacFusion Strain
Authors: Reznikoff William S. , Thornton Kathleen Pastick
Published: January 2020

Atrp-lacfusion strain ofEscherichia coliin which thelacstructural genes are part of the tryptophan operon has been used to isolatetrpregulatory mutants. This was accomplished by isolatinglac+colonies on either lactose-minimal agar or lactose-MacConkey indicator agar. Seventy-seven of 78lac+isolates contained mutations which mapped near thearalocus and most of these isolates were found to be 5-methyltryptophan-resistant after introduction of an F-trpepisome. Thelac+phenotypes of these 77 isolates were therefore probably the result oftrpR−mutations. The one remaining isolate carried a mutation which was not part of thetrpregulatory system.
Requirement of Succinate for the Growth of
Vibrio succinogenes
Authors: Niederman R. A. , Wolin M. J.
Published: January 2020

Vibrio succinogenes
required relatively small amounts of succinate for growth when formate plus nitrate was supplied as the energy source. The requirement for succinate was not apparent when formate plus fumarate was the energy source because fumarate is reduced to succinate.
l
-Asparagine, fumarate, and malate replaced succinate, and it appears likely that they do so by being converted to succinate. Formate plus
l
-aspartate or
l
-asparagine served as energy sources for growth. The stoichiometry of the reduction of aspartate with H
2
by resting cells suggests an aspartase reaction followed by reduction of fumarate to succinate. Oxalacetate or pyruvate plus bicarbonate did not substitute for succinate, nor did many other compounds that were tested.
14
C-succinate was mainly incorporated into the alcohol-soluble fraction of cells, although there was significant incorporation into the hot trichloroacetic acid-soluble and -insoluble fractions.
Analysis of a
Bacillus subtilis
Proteinase Mutant
Authors: Shoer Ruth , Rappaport Harry P.
Published: January 2020

A
Bacillus subtilis
mutant having a phenotype manifesting reduced extracellular proteolytic activity was investigated. An extracellular protein was isolated and shown by fingerprint analysis to be a fragment of the wild-type enzyme. By using previously established molecular weights for the wild-type enzyme (2.9 × 10
4
) and the two polypeptide chains derived from it (1.4 × 10
4
each), with the amino acid analysis and fingerprints of both wild-type and mutant proteins, a molecular weight of 1.57 × 10
4
was assigned to the mutant protein.
32
P-diisopropylphosphate labeling of the mutant protein showed only 1 in 53 molecules to be functional. Thin-layer chromatography on Sephadex G-75 demonstrated that the active molecules were separable from the bulk of the isolated protein and had the same mobility as the wild-type enzyme. Fingerprints of tryptic digests of
32
P-diisopropylphosphate-labeled wild-type and mutant proteins showed that the labeled peptides had identical characteristics.
Methanobacterium thermoautotrophicus
sp. n., an Anaerobic, Autotrophic, Extreme Thermophile
Authors: Zeikus J. G. , Wolee R. S.
Published: January 2020

The isolation of a new methanogenic bacterium,
Methanobacterium thermoautotrophicus
sp. n., is described. Successful isolation required a medium containing inorganic salts, an atmosphere consisting of an 80:20 mixture of hydrogen-carbon dioxide, and incubation temperatures of 65 to 70 C. Isolates of
M. thermoautotrophicus
were gram-positive, nonmotile, irregularly curved rods which frequently formed long filaments. The organism was found to be an autotroph and a strict anaerobe, and to have a
p
H optimum of 7.2 to 7.6. The optimal temperature for growth was 65 to 70 C, the maximum being 75 C and the minimum about 40 C. The generation time at the optimum was about 5 hr. The deoxyribonucleic acid of
M. thermoautotrophicus
had a guanine plus cytosine (GC) content of 52 moles per cent, whereas
Methanobacterium
sp. strain M.O.H. had a GC content of 38%. When heated, intact ribosomes of
Methanobacterium
sp. strain M.O.H. were stable up to 55 C and had a T
m
of 73 C. In contrast, ribosomes of
M. thermoautotrophicus
were stable up to 75 C and had a T
m
of 82 C. Upon complete thermal denaturation, ribosomes of strain M.O.H. underwent a 59% hyperchromic shift, whereas those of the thermophile showed only a 20% increase in hyperchromicity. Methane formation in cell-free extracts of
M. thermoautotrophicus
was temperature-dependent and required hydrogen and carbon dioxide; methyl cobalamin served as a methyl donor, and addition of coenzyme M stimulated methanogenesis.
3-Phosphoglycerate Kinase from
Hydrogenomonas facilis
Authors: McFadden Bruce A. , Schuster Erwin
Published: January 2020

Phosphoglycerate kinase levels in
Hydrogenomonas facilis
were reasonably constant whether cells were utilizing or synthesizing hexose during growth. Specific enzyme activities (micromoles of 3-phosphoglycerate disappearing per minute per milligram of protein) at 30 C were 0.234, 0.391, 0.300, and 0.229 in the “soluble” fraction derived from cells grown on fructose, lactate, succinate, and glutamate, respectively. The enzyme was purified 300-fold from succinate-grown cells. The final preparation, which was not homogenous but was free from glyceraldehyde-3-phosphate dehydrogenase and adenylate kinase, had a specific activity at 30 C of 90 μmoles of 3-phosphoglycerate per min per mg of protein.
K
m
values for adenosine triphosphate (ATP), 3-phosphoglycerate, and Mg
++
were 0.16, 0.83, and 0.4 m
m
, respectively, at
p
H 7.4 and 30 C. Adenosine monophosphate (AMP) inhibited 23% at a ratio of AMP to ATP of 2.4, and the possible physiological implications of this inhibition are discussed. No evidence was found for an enzyme which catalyzes ATP-dependent conversion of 3-phosphoglycerate to 1,3-diphosphoglycerate, AMP, and phosphate.
Disruption of an Amino Acid Transport Mutant of
Neurospora crassa
by KCl
Authors: Travis G. , Wolfinbarger L. , Stuart W. Dorsey , DeBusk A. Gib
Published: January 2020

A double amino acid transport-deficient mutant (Pm
−
NB) of
Neurospora crassa
is shown to be altered in the molecular structure of its cell wall or membrane. This alteration was revealed by a high degree of cellular disruption and cell-cell interaction following extraction by a high molar concentration of KCl.
Effect of
d
-Cycloserine on Transformation in Group H Streptococcus, Strain Challis
Authors: Perry Dennis
Published: January 2020

d
-Cycloserine (
d
-CS), a selective inhibitor of bacterial cell wall biosynthesis, inhibited transformation in group H streptococcus, strain Challis, by preventing the development of the competent state. The incubation of strain Challis cells with
d
-CS resulted in the production of a substance which inhibited the action of competence factor on these cells.
d
-CS had an enhancing effect on transformation when deoxyribonucleic acid uptake or phenotypic expression was allowed to occur in its presence.
Structure and Replication of Chromosomes in Competent Cells of
Bacillus subtilis
Authors: Erickson Robert J. , Copeland James C.
Published: January 2020

Competent cultures of
Bacillus subtilis
168 were fractionated on gradients of Renografin-76 to obtain a population enriched for competent cells. The cells in this fraction contained two nuclear bodies. The competent cell fraction synthesized deoxyribonucleic acid and ribonucleic acid at reduced rates compared to the noncompetent cell fraction and appeared to divide synchronously upon incubation. The state of the chromosome in competent cells was determined by density transfer experiments and marker frequency analyses. The results are consistent with a competent cell possessing two, or a multiple of two, chromosomes, one complete and the other partially duplicated. During subsequent growth the partially completed chromosome replicates preferentially.
Ribose Utilization by
Veillonella alcalescens
Authors: Kafkewitz David , Delwiche E. A.
Published: January 2020

The utilization of ribose by
Veillonella alcalescens
has been further investigated. Nonfermentation of ribose is not a result of a phosphorylation lesion since ribose-phosphorylating activity was measured in cell extracts. Resting cells accumulated ribose-5-phosphate and nucleotides when
14
C-ribose was provided; no other sugar phosphates were detectable. Resting cells that were shifted to growth conditions polymerized rather than degraded the accumulated ribose compounds. Cell extracts contained a fructose diphosphate phosphatase. Ribose-5-phosphate, glucose-6-phosphate, and fructose-6-phosphate were not hydrolyzed. It is postulated that the nonfermentation of ribose is not due to any metabolic lesions, but is a consequence of metabolic control at the fructose diphosphate level of glycolysis.
Guanine Plus Cytosine Contents of the Deoxyribonucleic Acids of Some Sulfate-Reducing Bacteria: a Reassessment
Authors: Skyring G. W. , Jones H. E.
Published: January 2020

Guanine plus cytosine (GC) contents of the deoxyribonucleic acids of
Desulfovibrio
and
Desulfotomaculum
have been used as a basis for classification. Some of these data have been incorrectly calculated, resulting in errors of as much as 5% GC. This situation has been corrected by a reanalysis of existing data and by the contribution of new data.
Conditional Lethality of
recA
and
recB
Derivatives of a Strain of
Escherichia coli
K-12 with a Temperature-Sensitive Deoxyribonucleic Acid Polymerase I
Authors: Monk M. , Kinross J.
Published: January 2020

We have isolated a strain of
Escherichia coli
K-12 carrying a mutation,
polA12
, that results in the synthesis of a temperature-sensitive deoxyribonucleic acid (DNA) polymerase I. The double mutants
polA12 recA56
and
polA12 recB21
, constructed at 30 C, are inviable at 42 C. About 90% of the cells of both double mutants die after 2 hr of incubation at 42 C. Both double mutants filament at 42 C and show a dependence on high cell density for growth at 30 C. In
polA12 recB21
cells at 42 C, DNA and protein synthesis gradually stop in parallel. In
polA12 recA56
cells, DNA synthesis continues for at least 1 hr at 42 C, and there is extensive DNA degradation. The results suggest that the primary lesion in these double mutants is not in DNA replication per se.
Composition of Fatty Acids and Carbohydrates in
Leptospira
Authors: Kondo Eiko , Ueta Nobuo
Published: January 2020

The fatty acid and monosaccharide composition of four pathogenic and two saprophytic strains of
Leptospira
was analyzed by gas chromatography (GC) and GC-mass spectrometry. Among the fatty acids, palmitic acid was most abundant and constituted 30 to 50% of the total fatty acids. Even-numbered unsaturated acids including octadecenoic, hexadecenoic, octadecadienoic, and tetradecadienoic acids comprised 40 to 60% of the total fatty acids. Tetradecanoic acid was about 5% in saprophytic strains, but 1% or less in pathogenic strains. The amount of chloroform-methanol extract of
L. biflexa
strain Ancona was 14 to 20% of the dry weight of the cell. Tetradecadienoic acid was found in the chloroform-methanol insoluble fraction, suggesting the presence of the acid in a bound form. GC analysis of monosaccharides revealed the existence of arabinose, xylose, rhamnose, mannose, galactose, glucose, glucosamine, and muramic acid in the cells. Among the neutral sugars, glucose was a minor component and was especially low in pathogenic strains. Total pentose content was about two to three times greater than total hexose.
Recombinant F′ Factors from
Escherichia coli
K-12 Strains Carrying
recB
or
recC
Authors: Hall J. D. , Howard-Flanders P.
Published: January 2020

The frequency of genetic exchanges between F′ factors and the bacterial chromosome was studied in recombination-deficient
Escherichia coli
mutants under conditions in which the recombinant F′ factors were immediately transferred to new hosts. In a series of double matings, F101-1
thr
+
leu
−
episomes were first transferred into each of four intermediate F
−
thr
−
leu
+
strains carrying various
rec
alleles. After the original F′ donors were killed with phage T6, the F101-1 episomes were then transferred from the intermediate cells to F
−
thr
−
leu
−
Str
R
recA
−
females. Recipients of nonrecombinant episomes formed Thr
+
(Str
R
) colonies, and recipients of recombinant episomes formed Leu
+
(Str
R
) colonies. A comparison of the numbers of Leu
+
(Str
R
) and Thr
+
(Str
R
) colonies shows that
recB
−
males formed 18 to 21% and
recC
−
formed 47 to 60% of the wild-type level of recombinant episomes that could be detected after transfer. No recombinant episomes were detected using a
recA
−
intermediate strain. If the intermediate strains harboring the F101 episomes were purified, allowed to grow for 50 generations, and then mated with the
recA
−
recipient, recombinant episomes were transferred at 8% of the wild-type level for
recB
−
and 13% for
recC
−
. In contrast, only 0.4 and 0.6% of the normal number of recombinants were obtained from crosses between Hfr Cavalli donors and the same
recB
−
and
recC
−
strains. Recombinant episomes were detected with greater frequency among newly formed
rec
+
,
recB
−
, and
recC
−
partial diploids than in those which were 50 generations old.
Physiological Factors in the Regulation of Alkaline Phosphatase Synthesis in
Escherichia coli
Authors: Wilkins Adam S.
Published: January 2020

Alkaline phosphatase is induced in excess phosphate media by starvation either for pyrimidines or for guanine. Induction is observed both during starvation, after a lag period, and following a period of starvation. Induction is not caused by a lowering of the internal orthophosphate pool, but is linked to alterations in the levels of the nucleotide pools. Experiments with purine-requiring mutants suggest that phosphatase is induced in wild-type strains by an adenine nucleotide. Mutations in the
phoR
gene can produce differential responses to the different starvation regimes.
Detection of Cholesterol in Cell Membranes by Use of Bacterial Toxins
Authors: Pendleton I. R. , Kim K. S. , Bernheimer A. W.
Published: January 2020

A method is described for the detection of cholesterol in membranes from erythrocytes, mycoplasmas, and bacterial cells by a ferritin-labeling technique. Membranes treated with cereolysin, a bacterial hemolysin which specifically binds to cholesterol, and then treated with ferritin-antitetanolysin, were specifically ferritin-labeled for cholesterol. A similar antigen-antibody system, streptolysin O-ferritin-antistreptolysin, was also used successfully with erythrocyte membranes. There was an uneven distribution of ferritin in erythrocyte membranes suggesting that the distribution of cholesterol may not be entirely random.
Mycoplasma gallisepticum
was intensely labeled, but
Acholeplasma laidlawii
with or without cholesterol in the membranes was not labeled, suggesting an unusual location for cholesterol in
A. laidlawii
membranes. As controls, two of three species of bacterial membranes lacking cholesterol were not ferritin-labeled.
Genetic Locus of a Gene Affecting Leucine Transport in
Salmonella typhimurium
Authors: Thorne Grace M. , Corwin Laurence M.
Published: January 2020

By using a series of deletion mutations in the region of the tryptophan operon, it has been shown that a gene governing the transport of leucine maps on the side of the
chr
locus distal to the
trp
operon.
Efficiency of Thymidine Incorporation in
Escherichia coli
B/r as a Function of Growth Rate
Authors: Kubitschek H. E. , Valdez D. , Freedman M. L.
Published: January 2020

Short-term labeling with radioactive thymidine led to inaccurate estimates of deoxyribonucleic acid synthesis at some growth rates in steady-state cultures of
Escherichia coli
B/r. Estimates were corrected in chemostat cultures by adding adenosine, a known inhibitor of thymidine phosphorylase.
Characterization of Aminoacyl Transfer Ribonucleic Acid Formation Stimulated by Polyamines
Authors: Takeda Yoshifumi , Matsuzaki Kazuyoshi , Igarashi Kazuei
Published: January 2020

From a comparative study of aminoacyl transfer ribonucleic acid (tRNA) formation stimulated by polyamines or by Mg
2+
, it is shown that both reactions have the same requirements for adenosine triphosphate, tRNA, and aminoacyl-tRNA synthetase. Reaction kinetics are similar in both reactions. The same tRNA is aminoacylated in the presence of either spermine of Mg
2+
. Aminoacyl-tRNA formed in the presence of polyamines can be a donor of amino acids in polypeptide synthesis.
Deoxyribonucleic Acid Distribution in
Bacillus subtilis
Independent of Cell Elongation
Authors: Mendelson Neil H.
Published: January 2020

A temperature-sensitive DNA
−
mutant of
Bacillus subtilis
has been studied during the resumption of deoxyribonucleic acid (DNA) synthesis following a 45 to 30 C temperature shift. For several hours after return to 30 C, DNA synthesis proceeds although the cells fail to elongate appreciably. Autoradiographs of cell populations synthesizing DNA during the recovery period demonstrate that DNA can become distributed to previously unoccupied regions along the cell length. By varying the labeling regime, newly synthesized DNA as well as DNA present at the time of transfer from 45 to 30 C were followed independently. Measurements of the percent of cell length covered by grains (
3
H-thymine in DNA) demonstrate the progressive refilling of DNA-vacant cell regions by both newly synthesized and original DNA. These data indicate that cell surface growth is not an absolute requirement for segregation of bacterial DNA.
Regulation of the Bacterial Cell Wall: Isolation and Characterization of Peptidoglycan Mutants of
Staphylococcus aureus
Authors: Chatterjee Anadi N. , Young Frank E.
Published: January 2020

Temperature-sensitive mutants of
Staphylococcus aureus
H which require 1.0
m
NaCl for growth at 42 C can be divided into two major classes. Most of the mutants (class A) do not accumulate nucleotide precursors of cell wall biosynthesis in the absence of salt at the nonpermissive temperatures, whereas the class B mutants accumulate these precursors. The most extensively studied mutant RUS 1 (carrying
peg-1
) is defective in biosynthesis of peptidoglycan at the nonpermissive conditions as evidenced by: (i) reduced incorporation of cell wall precursors into peptidoglycan; (ii) accumulation of the nucleotide, uridine diphosphate (UDP) muramyl-
l
-alanyl-
d
-glutamic acid; (iii) reduced specific activity of UDP
N
-acetylmuramyl (MurNAc)-
l
-alanyl-
d
-glutamate:
l
-lysine ligase (EC 6.3.2.7); and (iv) an increased susceptibility to lysis with sodium dodecyl sulfate. Addition of 1.0
m
NaCl reverses these defects with the exception of the specific activity of UDP-MurNAc-
l
-alanyl-
d
-glutamate:
l
-lysine ligase. Nevertheless, the structure of the cell wall is normal at the nonpermissive conditions if 1.0
m
NaCl is present. An alteration in the binding of a fluorescent dye, 8-anilino-1-napthalene-4-sulfonic acid at the nonpermissive conditions in the absence of 1.0
m
NaCl suggests that there may also be defects in the membrane in this strain.
Biochemical and Genetic Aspects of Nystatin Resistance in
Saccharomyces cerevisiae
Authors: Bard Martin
Published: January 2020

Two phenotypically distinct sets of nystatin-resistant mutants were investigated. One set is resistant, respiratory competent, and requires no lipid for growth. The other set is more resistant, respiratory deficient, and lipid requiring (unsaturated fatty acid or sterol). Both sets show altered sterol composition as demonstrated by the Liebermann-Burchard colorimetric reaction, ultraviolet spectrophotometry, and gas-liquid chromatography. Genetic analysis indicates that all nystatin-resistant mutants can be placed into one of six distinct genetic groups. The phenotype's nystatin resistance, lipid requirement, and respiratory deficiency are recessive. There was one case of allelism for mutants from different sets. Revertants of mutants which have the tripartite phenotype retain a residual level of nystatin resistance, but they are no longer lipid requiring or respiratory deficient. Growth studies in mutants which have the tripartite phenotype reveal that the addition of ergosterol to the growth medium results in decreased resistance to nystatin.
Photooxidative Death in Blue-Green Algae
Authors: Abeliovich A. , Shilo M.
Published: January 2020

When incubated in the light under 100% oxygen, wild-type blue-green algae (
Anacystis nidulans, Synechococcus cedrorum
) die out rapidly at temperatures of 4 to 15 C, and at 35 C (or at 26 C in the case of
S. cedrorum
) in the absence of CO
2
. Photosynthesis is impaired in these cells long before they die. Blocking of photosystem II at high temperatures in the presence of CO
2
sensitizes the algae to photooxidative death. Photooxidative death and bleaching of photosynthetic pigments are separable phenomena. Photooxidative conditions were demonstrated in Israeli fish ponds using
A. nidulans
as the test organism during dense summer blooms, when dissolved CO
2
is low, and in winter, when water temperatures generally drop below 15 C. This finding suggests that photooxidative death may be responsible for the sudden decomposition of blue-green blooms in summer, and may be a factor in the absence of blue-green blooms in winter.
Methionine Adenosyltransferase and Ethionine Resistance in
Saccharomyces cerevisiae
Authors: Mertz Janet E. , Spence K. D.
Published: January 2020

The methionine adenosyltransferase is repressed in
Saccharomyces cerevisiae
during growth in the presence of excess methionine. The relationship of this repression to the level of intracellular
S
-adenosylmethionine is discussed. In conjunction with these studies, an ethionine-resistant mutant has been investigated which has a low level of methionine adenosyltransferase under all conditions tested. The mechanism of ethionine resistance in the latter strain apparently depends on its inability to form large quantities of intracellular
S
-adenosylethionine. With respect to the methionine adenosyltransferase, there is no apparent interaction between ethionine-resistant and ethionine-sensitive alleles when both are present in the heterozygous diploid.
Observations on the Post-Transcriptionally Modified Nucleotides in the 16
S
Ribosomal Ribonucleic Acid
Authors: Sogin M. L. , Pechman K. J. , Zablen L. , Lewis B. J. , Woese C. R.
Published: January 2020

The 16
S
(18
S
) ribosomal ribonucleic acids from a number of organisms were screened for the presence of (some of) the post-transcriptionally modified oligomers found in
Escherichia coli
16
S
ribosomal ribonucleic acid. All prokaryotic 16
S
species contained all of the modified oligomers tested, with the sole exception that one such oligomer was missing in
Alcaligenes faecalis
. The post-transcriptional modifications in all of these oligomers except one appear to occur at the later stagesin ribosomal maturation.
Isoleucine and Valine Metabolism in
Escherichia coli
XVIII. Induction of Acetohydroxy Acid Isomeroreductase
Authors: Ratzkin Barry , Arfin Stuart , Umbarger H. E.
Published: January 2020

The regulation by substrate induction of the acetohydroxy acid isomeroreductase was studied in
Escherichia coli
. Induction was inhibited by chloramphenicol and rifampin. The addition of rifampin resulted in a decay of the capacity to form isomeroreductase. This was attributed to the breakdown of the isomeroreductase messenger, which had a half-life of about 45 sec at 37 C. Induction of isomeroreductase was enhanced by including glucose in the medium. This effect was shown to be due in part to the lowering of the
p
H of the medium, which presumably made inducer entry more rapid.
Factors Affecting Virulence of
Shigella flexneri
: Defective Methionine Synthesis in an
Escherichia coli-Shigella
Hybrid
Authors: Rothman Sara W. , Corwin Laurence M.
Published: January 2020

An
Escherichia coli-Shigella flexneri
hybrid of intermediate virulence was studied to determine whether its shorter survival in host cells might be due to a metabolic defect. Investigation of its growth in minimal glucose medium showed that the hybrid, like its
E. coli
parent, had a longer lag phase and a slower growth rate than its virulent
Shigella
parent. Methionine was found to increase the growth rate of the hybrid. The
Shigella
parent of the hybrid can synthesize methionine normally, but the
E. coli
parent has a point mutation in its
metA
gene. Since it synthesizes enough methionine to grow slowly, it is postulated that the hybrid strain has a hybrid
metA
gene, that is, a gene composed partly of deoxyribonucleic acid (DNA) from
E. coli
, with the balance of the DNA from
S. flexneri
. Phage P1-mediated transduction, with the
metA
−
E. coli
parent as recipient and the
Shigella
parent as donor, yielded a few transductants that responded to methionine in the same way the hybrid did. Many more transductants of the hybrid type were produced when the hybrid strain was used as a donor. It is suggested that this poorly functioning gene acts synergistically with the hybrid strain's relaxed synthesis of ribonucleic acid to prevent its survival in the host.
Purification and Properties of the Adenosine Diphosphate-Glucose and Uridine Diphosphate-Glucose Pyrophosphorylases of
Mycobacterium smegmatis
: Inhibition and Activation of the Adenosine Diphosphate-Glucose Pyrophosphorylase
Authors: Lapp David , Elbein Alan D.
Published: January 2020

Crude extracts of
Mycobacterium smegmatis
catalyzed the synthesis of adenosine diphosphate-glucose (ADP-Glc), cytidine diphosphate-glucose, guanosine diphosphate-glucose (GDP-Glc), thymidine diphosphate-glucose (TDP-Glc), and uridine diphosphate-glucose (UDP-Glc). In these crude enzyme fractions, high concentrations of trehalose-P inhibited the ADP-Glc and GDP-Glc pyrophosphorylases but did not effect the UDP-Glc or TDP-Glc pyrophosphorylases. Both the ADP-Glc pyrophosphorylase and the UDP-Glc pyrophosphorylase were partially purified (about 140-fold and 60-fold, respectively), and their properties were compared. For the ADP-Glc pyrophosphorylase, the
K
m
for adenosine triphosphate was 6 × 10
−4
m
, whereas that for glucose-1-P was 8 × 10
−4
m
. The optimal concentration of Mg
2+
was 1 × 10
−3
m
, and the
p
H optimum was 8.5. For the UDP-Glc pyrophosphorylase, the
K
m
for uridine triphosphate was 1 × 10
−3
m
and for glucose-1-P was 2 × 10
−3
m
. The optimal Mg
2+
concentration was 1 × 10
−3
m
, and the
p
H optimum was about 8.0. The purified ADP-Glc pyrophosphorylase was inhibited by fructose-6-P, fructose-1, 6-diphosphate, glucose-6-P, and phosphoenolpyruvate. On the other hand, trehalose, trehalose diphosphate, sodium pyruvate, and ribose-5-P did not effect the ADP-Glc pyrophosphorylase. None of these compounds, including trehalose-P, had any effect on the UDP-Glc pyrophosphorylase.
Isolation and Properties of a Fluorescent Compound, Factor
420
, from
Methanobacterium
Strain M.o.H
Authors: Cheeseman P. , Toms-Wood A. , Wolfe R. S.
Published: January 2020

A new fluorescent compound, factor
420
(F
420
), which is involved in the hydrogen metabolism of hydrogen-grown
Methanobacterium
strain M.o.H. has been isolated and purified. Acid hydrolysis of this compound with 6
m
HCl for 24 hr releases a ninhydrin-positive compound (glutamic acid), an acid-stable chromophore, phosphate, and an ether-soluble phenolic component. Factor
420
may be reduced by either sodium dithionite or sodium borohydride at
p
H 7.3 with concomitant loss of its fluorescence and its major absorption peak at 420 nm. Crude cell-free extracts of strain M.o.H. reduce F
420
only under a hydrogen atmosphere. F
420
is photolabile aerobically in neutral and basic solutions, whereas the acid-stable chromophore is not photolabile under these conditions. An approximate molecular weight of 630 ± 8% for F
420
was determined by Sephadex G-25 chromatography. At the present time, F
420
is proposed as a trivial name for the unknown fluorescent compound because of its strong absorption maximum of 420 nm at
p
H 7.
Location of Calcium WithinBacillusSpores by Electron Probe X-Ray Microanalysis
Authors: Scherrer René , Gerhardt Philipp
Published: January 2020

Spectroscopic microanalysis of the element-characteristic X rays produced by a scanning electron microprobe was employed to detect calcium and carbon in both intact and thin-sectioned spores ofBacillus cereusT andB. megateriumQM B1551. Linear scan profiles and multilinear scan images of the X-ray emissions for calcium (CaKα) were compared with those for carbon (CKα) as an index of mass. Location was accomplished by stereological comparisons with secondary electron images and conventional transmission electron micrographs. Although the elements could be detected at the attogram level theoretically, spatial resolution was limited to ∼500 to 1,000 nm in an intact spore, e.g., by the primary electron beam diameter, the electron-excited spore microvolume, and the type of specimen support. The resolution was improved to ∼100 to 200 nm by use of thin-sectioned spores, with precautions to prevent calcium leakage from the specimen during preparations. In both intact and sectioned spores, calcium was distributed throughout the spore, similarly to carbon, and concentrated mainly in a central region corresponding to the spore protoplast.
P22-Mediated Transduction Analysis of the Rough A (
rfa
) Region of the Chromosome of
Salmonella typhimurium
Authors: Sanderson Kenneth E. , Saeed Yousuf A.
Published: January 2020

Seven temperature-sensitive rough mutants of
Salmonella typhimurium
were found to be sensitive to smooth-specific phages at low temperature (25 C, 30 C) and resistant or partially resistant to rough-specific phages, whereas at high temperatures (37 C, 45 C) they were resistant or partially resistant to smooth-specific phages but sensitive to rough-specific phages. These data indicate that at low temperature each strain makes lipopolysaccharide which is relatively normal, but at high temperatures O-specific side chains are not added to the lipopolysaccharide. At 45 C, these strains have the R-res-1 or R-res-2 phage sensitivity phenotype, and their genetic lesions map by P22-mediated transduction in the
rfa
gene cluster between
cysE-pyrE
, suggesting a mutation in genes with transferase functions. P22-mediated joint transduction with temperature-sensitive
rfa
mutants, leaky
rfa
mutants, and
rfa
P22 lysogens have shown the following order of genes in the
S. typhimurium
linkage map:
xyl-mtlA-mtlB-cysE-rfaF-rfaG-pyrE
. An
rfaE
allele was not jointly transduced in the
cysE-pyrE
segment.
Insertion of the F Factor into the Cluster of
rfa
(Rough A) Genes of
Salmonella typhimurium
Authors: Sanderson Kenneth E. , Saeed Hamida
Published: January 2020

From F
+
strains of
Salmonella typhimurium
, isolates were obtained representing two new classes of Hfr strains, HfrK1 and HfrK2, in which the insertion of the F factor into the
rfa
genes results in chromosome mobilization either clockwise or anticlockwise from
rfa
, and in the Rfa phenotype. The point of insertion of the F factor into the cluster of
rfa
genes, revealed by studies of the early transfer of their normal alleles, is as follows:
xyl-cysE-rfa-657
(HfrK2-1, SA540 →)–(← HfrK1-1, SA458)–
rfaG
-(← HfrK1-2, SA464)–
pyrE-metA
Pleiotropic Properties and Genetic Organization of the
tolA, B
Locus of
Escherichia coli
K-12
Authors: Bernstein Alan , Rolfe Barry , Onodera Kazukiyo
Published: January 2020

Colicin-tolerant mutants of
Escherichia coli
K-12, which map near
gal
at 17 min (
tolA, B
mutants), have been isolated and characterized. These mutants exhibited a very broad spectrum of phenotypic changes consistent with the interpretation that they are cell surface mutants. In addition to being colicintolerant and sensitive to deoxycholate and ethylenediaminetetraacetic acid,
tolA, B
mutants are sensitive to vancomycin, bacitracin, and dodecyl sulfate. The
tolA, B
mutants from most strains also formed mucoid colonies at 30 C on nutrient agar plates and had a greatly increased plating efficiency for lysisdefective
S
mutants of bacteriophage λ. Complementation analysis showed that the four phenotypic groups of
tol
mutants that map near
gal
fall into three complementation groups:
tolP, tolA
, and
tolB
. Recombination analysis by three-factor crosses established the order of the three groups as
tolP-tolA-tolB—gal
. Because of the wide variety of phenotypic changes that accompanies mutation to colicin tolerance, revertants were isolated to test whether single or multiple mutations were involved. The reversion analysis, as well as other genetic criteria, confirmed that only single mutations were involved, suggesting that these pleiotropic changes are a consequence of a single change in the
E. coli
cell surface.
Multivalent Repression of Aspartic Semialdehyde Dehydrogenase in
Escherichia coli
K-12
Authors: Boy Emmanuelle , Patte Jean-Claude
Published: January 2020

Mutants of
Escherichia coli
in which the lysine-sensitive aspartokinase is feedback-resistant are described. In these strains, as well as in the wild type, aspartic semialdehyde dehydrogenase is subject to multivalent repression by lysine, threonine, and methionine. When these amino acids were added to a culture in minimal medium, the differential rate of synthesis of the enzyme dropped to zero and remained there for about one generation.
Mutant Strains of
Escherichia coli
K-12 Exhibiting Enhanced Sensitivity to 5-Methyltryptophan
Authors: Kuhn Jonathan C. , Pabst Michael J. , Somerville Ronald L.
Published: January 2020

Eighteen mutants (designated MT
s
), isolated in
Escherichia coli
K-12, showed increased sensitivity to inhibition of growth by 5-methyltryptophan. All mutants were also much more sensitive to 4-methyltryptophan and 7-azatryptophan but exhibited near normal sensitivity to 5-fluorotryptophan and 6-fluorotryptophan. All of the mutations were linked to the
trp
operon. Their locations within the
trp
operon were established by deletion mapping. There was good agreement between the map position of an MT
s
mutation and a lowered activity of one of the tryptophan pathway enzymes. Three mutants, one of which contained a mutation that mapped within the
trpE
gene, were deficient in their ability to use glutamine as an amino donor in the formation of anthranilic acid. Another
trpE
mutation led to the production of an anthranilate synthetase with an increased sensitivity to feedback inhibition by tryptophan.
Host Cell Deoxyribonucleic Acid Polymerase I and the Support of T4 Bacteriophage Growth
Authors: George Donna , Rosenberg David
Published: January 2020

Ultraviolet irradiation of
Escherichia coli polA
−
cells reduces their capacity to support the growth of T4 phage. There is no additional loss of capacity observed in
pol tsA
−
recA
−
double mutants at the nonpermissive temperature. The reversion frequency of a T4
rII
mutant after ultraviolet irradiation is not changed by the absence of host deoxyribonucleic acid polymerase I.
Isoleucine and Threonine Can Prolong Protein and Ribonucleic Acid Synthesis in Pyridoxine-Starved Mutants of
Escherichia coli
B
Authors: Dempsey Walter B. , Sims Kathryn R.
Published: January 2020

Pyridoxineless mutants of
Escherichia coli
B stopped incorporation of nucleosides into trichloroacetic acid-insoluble material about 40 to 60 min after pyridoxine starvation was initiated, whereas incorporation of amino acids (measured the same way) slowed but did not stop for several hours. Both these incorporations and cell density were increased most effectively by the presence of either threonine or isoleucine. Arginine, glutamate, histidine, methionine, tryptophan, and tyrosine also caused significant but less dramatic increases. Inducibility of β-galactosidase continued beyond the point where nucleic acids appeared to stop their synthesis, suggesting that messenger ribonucleic acid synthesis continued beyond ribosomal ribonucleic acid synthesis. This inducibility was also increased by isoleucine and threonine. The overall results suggest that the threonine-isoleucine biosynthetic pathway is the most sensitive to starvation for pyridoxine.
Homology Between the Deoxyribonucleic Acids of
Haemophilus influenzae
and
Haemophilus parainfluenzae
Authors: Boling M. E.
Published: January 2020

To determine the degree of homology between deoxyribonucleic acid (DNA) from
Haemophilus influenzae
and that from
Haemophilus parainfluenzae
, the two DNAs were hybridized by the membrane-filter technique. It was found that 44% of the DNA from each species was sufficiently homologous to allow hybrid formation.