bluuebunny/crossref_metadata_2025 huggingface dataset:
Cell Division of
Escherichia coli
BUG-6: Effect of Varying the Length of Growth at the Nonpermissive Temperature
Authors: Reeve John N. , Clark D. Joseph
Published: January 2020

When
Escherichia coli
BUG-6 is grown at 42 C and then returned to 30 C, the division kinetics during the recovery at 30 C are dependent on the length of time the cells were grown at 42 C. If chloramphenicol is added when the cells are shifted from 42 to 30 C, no division occurs if the period at 42 C is less than 4 min or more than 110 min. Maximum division occurs when the period at 42 C is 50 min. A discussion of these results with reference to a previously proposed model is presented.
Dihydrofolate Reductase Activity in Strains of
Streptococcus faecium
var.
durans
Resistant to Methasquin and Amethopterin
Authors: Rader Jeanne I. , Hutchison Dorris J.
Published: January 2020

Resistance to the antifolates methasquin and amethopterin has been studied in new strains of
Streptococcus faecium
var.
durans
. Two methasquin-resistant strains (SF/MQ, SF/MQ
T
) and an amethopterin-resistant strain (SF/AM) were selected independently from the wild-type
S. faecium
var.
durans
(SF/O). SF/MQ
T
is a thymine auxotroph. Total dihydrofolate reductase activity was elevated in each of the resistant strains. The greatest increase (36-fold) was observed in extracts of SF/AM. The methasquin-resistant strains, SF/MQ and SF/MQ
T
, had 29-fold and 8-fold, respectively, more dihydrofolate reductase activity than the parental strain. Total dihydrofolate reductase activity of SF/O was separable by gel filtration into two components: a folate reductase (11%) and a specific dihydrofolate reductase (89%). Folate reductase activity was associated with 88% of the total dihydrofolate reductase activity of SF/MQ
T
, with specific dihydrofolate reductase activity accounting for the remaining 12%. In SF/MQ and SF/AM, folate reductase activity was associated with 97% of the total dihydrofolate reductase activity. Studies of the inhibition by methasquin and amethopterin of partially purified folate reductase and specific dihydrofolate reductase of the mutant strains suggested that resistance was not accompanied by changes in the affinities of these enzymes for either antifolate.
Conditional Dihydrostreptomycin Resistance inBacillus subtilis
Authors: Staal S. P. , Hoch J. A.
Published: January 2020

Mutants resistant to dihydrostreptomycin were isolated and genetically analyzed inBacillus subtilis. Two new classes of mutants distinct from the ribosomalstrAlocus were found. One class,strB, was located betweenmetC3andura-1on the chromosome. The second class,strC, mapped in the spore gene region close to thespoAlocus. Both mutant classes were resistant to dihydrostreptomycin during growth but sensitive to the antibiotic during sporulation. Resuspension sporulation experiments with astrBmutant showed that sensitivity to the antibiotic was acquired early in the sporulation process. The germination and outgrowth ofstrBspores was sensitive to the antibiotic until growth commenced, whereupon the culture was resistant. Thus the mutants are sensitive to dihydrostreptomycin during both sporulation and germination but resistant during the growth phase.
Purification and Characterization of Acid Phosphatase V from
Aspergillus nidulans
Authors: Harsanyi Zsolt , Dorn Gordon L.
Published: January 2020

Acid phosphatase V of
Aspergillus nidulans
was purified by ammonium sulfate precipitation, gel filtration, and ion-exchange chromatography. The enzyme demonstrated a charge microheterogeneity on starch and acrylamide gel electrophoresis, but proved to be homogeneous on ultracentrifugation and gel filtration. Phosphatase V was found to be a classic acid orthophosphoric monoester phosphohydrolase, and it cleaved
p
-nitrophenylphosphate, glucose-6-phosphate, and uridine-5′-monophosphate at maximal rates. It was inhibited by fluoride, borate, and molybdate ions, and demonstrated end-product inhibition by inorganic phosphate. Metallic ions or cofactors were not required for activity. The molecular weight was estimated to be 100,000, the
S
20,w
was calculated to be 4.1, and the
p
H optimum was found to be 6.1.
Ribosomal Alterations Controlling Alkaline Phosphatase Isozymes in
Escherichia coli
Authors: Piggot P. J. , Sklar M. D. , Gorini L.
Published: January 2020

Different patterns of isozymes were obtained by starch-gel electrophoresis of alkaline phosphatase from
Escherichia coli
strains differing only by
strA
or
ram
mutations, or both, in the 30
S
ribosomal subunit. The isozyme spread was reduced in
strA
and increased in
ram
strains; this strictly parallels the restriction and enhancement of translational ambiguity produced by these mutations. Streptomycin present during growth had an effect similar to
ram
on both isozymes and ambiguity. The three isozymes analyzed have different N-terminal residues: aspartic acid, valine, and threonine. Different patterns of isozymes were also obtained in a wild-type strain through the specific action of exogenous arginine. A link between the mechanism of the effect of arginine and that of the ribosome is not obvious. The possibility is discussed that in both cases, although by different mechanisms, N-terminals are formed with different sensitivity to limited degradative attack.
Isolation and Characterization of Two Cell Types ofCoxiella burnetiPhase I
Authors: Wiebe Michael E. , Burton Paul R. , Shankel Delbert M.
Published: January 2020

Two morphologically distinct cell types ofCoxiella burnetiphase I have been separated on the basis of unique buoyant densities. When centrifuged to equilibrium in cesium chloride or density gradients of sucrose or Renografin, the cells band in two zones. Electron micrographs of ultrathin sections of the two cesium chloride-separated cell types indicate a considerable number of morphological differences. The lower-density cells are small, compact, and rodshaped and have very dense nucleoids. The cell type of highest density is larger, rounded, and more pleomorphic, and the nucleoid filaments are more dispersed. The two cell types are nearly identical in sedimentation rates, and both infect chick yolk sac cells and are lethal to chick embryos. They convert to a mixture of cell types when cultured separately. Treatment with Formalin induces all cells to band at the same position when centrifuged to equilibrium in cesium chloride. The cell type variance was found to be independent of the antigenic phase phenomenon ofC. burneti.
Dissociation of Lac Messenger Ribonucleic Acid Transcription from Translation During Recovery from Inhibition of Protein Synthesis
Authors: Artman Michael , Ennis Herbert L.
Published: January 2020

Studies were made of the synthesis of Lac messenger ribonucleic acid (mRNA) by
Escherichia coli
in the absence of protein synthesis and of the coupling of transcription of
lac
operon to translation. Lac mRNA was not synthesized in the presence of chloramphenicol, and its synthesis steadily decreased during K
+
deprivation and treatment with puromycin. Since under these conditions total mRNA synthesis is not inhibited it is suggested that the control of Lac mRNA is distinct from that which regulates total mRNA synthesis. Lac mRNA synthesized during recovery from K
+
starvation or from chloramphenicol inhibition is not translated into functional enzyme, suggesting translational control over β-galactosidase synthesis.
Isolation of Morphological Mutants of
Agrobacterium tumefaciens
Authors: Fujiwara Tamio , Fukui Sakuzo
Published: January 2020

Morphological mutants were isolated from a wild strain of
Agrobacterium tumefaciens
at a high frequency by treatment with a nitrosoguanidine. Seventeen of the 20 mutants isolated were temperature-sensitive. At 27 C, the mutant cells were rod-shaped and at 37 C, spherical or branched, whereas the wild-type cells were rod-shaped at both temperatures.
Relationship Between Yield of Protoplasts and Growth Phase in
Saccharomyces
Authors: Shahin M. M.
Published: January 2020

A number of generations must occur in the presence of glucose before daughter cells of stationary or old cultures become amenable to protoplast formation by the action of snail enzyme.
Repair of Ultraviolet Light-Induced Damage to the Deoxyribonucleic Acid of
Neurospora crassa
Authors: Worthy Thomas E. , Epler J. L.
Published: January 2020

A method is described for labeling a specific pyrimidine in the deoxyribonucleic acid (DNA) of
Neurospora crassa
. In cells grown in the presence of [
5
-
3
H
]-uridine, more than 97% of the radioactivity associated with the DNA had been incorporated into cytosine. The specific activity of the labeled DNA was approximately 3 × 10
3
counts per min per μg. The DNA was isolated by elution from hydroxyapatite columns with sodium phosphate buffer (0.40
m
,
p
H 6.8). This procedure was used to demonstrate that in vegetative cells of
N. crassa
both photoreactivation and excision repair are operative, as measured by the removal of ultraviolet light-induced cytosine-containing dimers.
Tryptophan Synthetase in
Euglena gracilis
Strain G
Authors: Lara J. Cano , Mills S. E.
Published: January 2020

The five enzyme activities in the synthesis of
l
-tryptophan have been obtained in extracts of
Euglena gracilis
. One of these, tryptophan synthetase, has been studied in detail. The general catalytic properties of tryptophan synthetase, including the range of reactions catalyzed and its substrate and cofactor affinities, are similar to those reported for other organisms. The
Euglena
enzyme has two properties never previously observed for tryptophan synthetase. First, the rate of catalysis of the conversion of indole-glycerol phosphate to
l
-tryptophan remained at its maximal value and was unaffected by the ionic environment up to 0.3
m
KCl. In contrast, the conversion of indole to tryptophan showed a sharp maximum at 0.08
m
KCl. Second, the enzyme is a component of a complex that includes every enzyme in the pathway committed to tryptophan biosynthesis with the exception of anthranilate synthetase, the regulatory enzyme.
Effects of Fatty Acid Substitution on the Release of Enzymes by Osmotic Shock
Authors: Rosen Barry P. , Hackette S. Lynette
Published: January 2020

The release of enzymes by osmotic shock from
Escherichia coli
strain 30E, an unsaturated fatty acid auxotroph, was examined in culture supplemented with either
cis
- or
trans
-unsaturated fatty acids. Cultures grown in oleate-supplemented medium release a large fraction of the total cyclic phosphodiesterase, acid hexose phosphatase, and 5′-nucleotidase following osmotic shock. Cultures grown in elaidate-supplemented medium release much less of these same enzymes after shock treatment. Cultures grown with either supplementation show total release of these enzymes upon conversion to spheroplasts, demonstrating that the enzymes are in the periplasmic space in both cases. Cultures grown with either oleate or elaidate as fatty acid source were washed and suspended in medium containing the other isomer. The change from oleate to elaidate resulted in a rapid decrease in ability of the cells to release the three enzymes after osmotic shock so that within a 25% increase in cell mass the culture responded to osmotic shock as would a culture grown overnight in elaidate-supplemented medium. The reverse experiment resulted in a gradual increase in the ability of the cells to respond to osmotic shock. The outer membrane of
E. coli
is altered by the incorporation of elaidate, as indicated by electron microscopic data.
Serine Biosynthesis and Its Regulation in
Bacillus subtilis
,
Authors: Ponce-De-Leon Manuel M. , Pizer Lewis I.
Published: January 2020

Cell-free extracts of
Bacillus subtilis
strains GSY and 168 convert
14
C-phosphoglycerate to
14
C-serine phosphate and
14
C-serine. These reactions indicate a functional phosphorylated pathway for serine biosynthesis in these cells. The addition of serine to the incubation mixture inhibited the formation of both radioactive products. Extracts of mutant strains that require serine for growth lacked the capacity to synthesize serine phosphate, confirming that the phosphorylated pathway was the only functional pathway available for serine synthesis. Serine phosphate phosphatase and phosphoglycerate dehydrogenase activity were demonstrated in cell extracts, and the phosphoglycerate dehydrogenase was shown to be inhibited specifically by
l
-serine. The extent of serine inhibition increased when the temperature was raised from 25 to 37 C, and the thermal stability of the enzyme was enhanced by the presence of the inhibitor serine or the coenzyme reduced nicotinamide adenine dinucleotide. At 37 C the curve representing the relationship between phosphoglycerate concentration and enzyme velocity was biphasic, and the serine inhibition which was competitive at low substrate concentrations became noncompetitive at higher concentrations.
Comparative Immunological and Enzymatic Study of the Tryptophan Synthetase β2Subunit in theEnterobacteriaceae
Authors: Rocha Victor , Crawford Irving P. , Mills Stanley E.
Published: January 2020

The β2subunits of tryptophan synthetase, formula α2β2, fromEscherichia coli, Shigella dysenteriae, Enterobacter aerogenes, Salmonella typhimurium, andSerratia marcescenswere compared by three criteria. (i) αβ association constants for the various β2subunits andE. coliα subunit varied between 3.6 × 108m−1forE. coliand 0.33 × 108m−1forS. marcescens; values for the other organisms were intermediate. (ii) Antiserum neutralization of the β2subunit enzyme activity using anti-E. coliβ2serum showed significant cross-reaction among the organisms (E. coli, 1.0;S. dysenteriae, 0.98;S. typhimurium, 0.67;E. aerogenes, 0.61;S. marcescens, 0.42). (iii) Quantitative microcomplement fixation showedE. coliβ2andS. marcescensβ2subunits to have an index of dissimilarity of 1.8 while the other organisms had intermediate indexes. Similar complement fixation data were obtained with antisera from separate rabbits and from first course and boost sera. These findings suggest that the general surface structure and the respective α subunit binding site of the β2subunits from theseEnterobacteriaceaehave been strongly conserved.
Bacterial Conjugation Under Anaerobic Conditions
Authors: Stallions Donald R. , Curtiss Roy
Published: January 2020

Chromosome transfer in
Escherichia coli
has been shown to occur at high frequencies in an anaerobic environment.
Kinetic Properties of Phosphotransacetylase from
Veillonella alcalescens
Authors: Pelroy R. A. , Whiteley H. R.
Published: January 2020

The phosphotransacetylase of
Veillonella alcalescens
catalyzes a reversible reaction with Michaelis-Menten kinetics for all substrates. The rate of the reverse reaction (the synthesis of acetyl coenzyme A from acetyl phosphate) was 6.5 times greater than the rate of the forward reaction (the synthesis of acetyl phosphate from acetyl coenzyme A). The apparent
K
m
values determined for the forward reaction were 8.6 × 10
−6
m
for acetyl coenzyme A and 9.3 × 10
−3
m
for phosphate. In the reverse reaction, the
K
m
values were 3.3 × 10
−4
m
for coenzyme A and 5.9 × 10
−4
m
for acetyl phosphate. The results of an analysis of the inhibition by end products in the forward and reverse directions were compatible with a random bi- bi- mechanism. The enzyme was inhibited by adenosine triphosphate and adenosine diphosphate but was not affected by reduced nicotinamide adenine dinucleotide or pyruvate. The inhibition by adenosine triphosphate was noncompetitive with respect to acetyl phosphate and competitive with respect to coenzyme A. MgCl
2
reversed the inhibition by adenosine triphosphate or adenosine diphosphate. The role of Mg
2+
and adenylates in the regulation of phosphotranscetylase activity is discussed.
Chromosome Transfer by Autonomous Transmissible Plasmids: the Role of the Bacterial Recombination (
rec
) System
Authors: Moody Eric E. M. , Hayes W.
Published: January 2020

The ability of autonomous transmissible plasmids or sex factors to transfer chromosomal genes to F
−
recipient bacteria has been investigated by using a series of
rec
+
and
recA
−
donor strains. It is concluded that chromosome transfer by most sex factors is virtually dependent upon the functional integrity of the bacterial recombination system. However, evidence is presented that suggests the existence of plasmid-specified mechanisms of interaction with the chromosome which are independent of the bacterial recombination system.
Deoxyribonucleate Binding and Transformation in
Rhizobium japonicum
Authors: Raina J. L. , Modi V. V.
Published: January 2020

Rhizobium japonicum
, capable of binding high-molecular-weight donor
32
P-labeled deoxyribonucleic acid (DNA) during late log phase in a competence medium, was transformed for streptomycin resistance with a frequency of transformation ranging between 0.02 and 0.08%. Eight to 10% of the homologous native
32
P-labeled input DNA was bound irreversibly in a temperature-dependent manner. Homologous denatured
32
P-labeled DNA was incapable of binding to the recipient under similar conditions. CsCl density gradient banding of the donor and recipient DNA indicated homology. The low frequency of transformation could be due to one or more steps that occur between DNA uptake and integration.
Effects of Acetate and Other Short-Chain Fatty Acids on Sugar and Amino Acid Uptake of
Bacillus subtilis
Authors: Sheu Chingju W. , Konings Wilhelmus N. , Freese Ernst
Published: January 2020

Acetate and other short chain
n
-fatty acids (C
1
-C
6
) inhibit strongly the uptake of
l
-serine or other
l
-amino acids but inhibit only weakly that of α-methylglucoside or fructose, whether measured in whole cells of
Bacillus subtilis
or in membrane vesicles that have been energized with reduced nicotinamide adenine dinucleotide (NADH),
l
-α-glycerol phosphate, or ascorbate plus phenazine methosulfate. The acetate inhibition is noncompetitive, as was shown for
l
-α-aminoisobutyric acid uptake by whole cells and for
l
-serine uptake by membrane vesicles. In membrane preparations, neither NADH oxidation nor the reduction of cytochromes by NADH are affected by fatty acids. All of these effects are similar to those of 2, 4-dinitrophenol. It is concluded that the fatty acids “uncouple” the amino acid carrier proteins from the cytochrome-linked electron transport system (to which they may be coupled via protein interaction or via a cation gradient).
Deoxyribonucleic Acid Base Composition of the Yeastlike and Mycelial Phases of
Histoplasma capsulatum
and
Blastomyces dermatitidis
Authors: Bawdon Roger E. , Garrison Robert G. , Fina Louis R.
Published: January 2020

The base composition in moles percent guanine plus cytosine (%GC) of both nuclear and mitochondrial deoxyribonucleic acid (DNA) isolated from the yeastlike and mycelial phases of the dimorphic fungal pathogens
Histoplasma capsulatum
and
Blastomyces dermatitidis
was determined by techniques of thermal denaturation and CsCl buoyant density gradient equilibrium centrifugation. The mean observed values for GC content of nuclear DNA from
H. capsulatum
and
B. dermatitidis
were 47.3 and 48.2%, respectively. What is speculated to be mitochondrial DNA was found to be 34.0% for
H. capsulatum
and 34.3% for
B. dermatitidis
. Thermal denaturation curves for
Blastomyces
DNA indicated a bimodality in thermal denaturation profiles, thereby suggesting a significant mitochondrial DNA contamination. Mitochondrial DNA appeared to represent a smaller percentage of the total DNA prepared from
Histoplasma
, and was not observed consistently to affect%GC values as determined by thermal denaturation profiles. On the basis of the now known perfect stage of
B. dermatitidis
(
Ajellomyces dermatitidis
) as a member of the family
Gymnoascaceae
, the close approximation of%GC content of nuclear DNA of this fungal organism with that of
H. capsulatum
suggests possible phylogenetic relationship. It is suggested that the just reported, but as yet unclassified, perfect stage of
H. capsulatum
may be found to be phylogenetically a primitive form of the
Gymnoascaceae
.
Allostery of 3-Deoxy-
d
-
arabino
-Heptulosonate 7-Phosphate Synthetase in
Clostridium
: Another Conserved Generic Characteristic
Authors: Jensen Roy A. , Twarog Robert
Published: January 2020

Enzymological studies were done to characterize the allosteric control of 3-deoxy-
d
-
arabino
-heptulosonate 7-phosphate (DAHP) synthetase in three species of
Clostridium
. Allosteric control was identified as feedback inhibition by phenylalanine and was qualitatively similar for the DAHP synthetases of
C. butyricum, C. acetobutylicum
, and
C. tetanomorphum
. Quantitative differences in the enzymology and kinetics of allosteric control distinguished
C. tetanomorphum
from
C. butyricum
and
C. acetobutylicum
. Crude extracts contained apparent proteolytic activity which could be fractionated from DAHP synthetase. The proteolytic activity was more labile than DAHP synthetase in extracts and was progressively inactivated by serial freeze-thaw treatments. Protease activity was at least partially inhibited by phenylmethylsulfonyl-fluoride. The method of comparative allostery of DAHP synthetase distinguishes the genera
Bacillus
and
Clostridium
, each having a strongly conserved pattern of regulation for DAHP synthetase. The data reinforce previous conclusions that allosteric control patterns governing the activity of DAHP synthetase are stable, reliable generic characteristics.
Mutants with Altered Glucose Repression of Amidase Enzymes in
Aspergillus nidulans
Authors: Hynes M. J.
Published: January 2020

Aspergillus nidulans
produces acetamidase and formamidase enzymes. The acetamidase is produced in reduced amounts during growth on glucose, whereas the formamidase is not greatly affected. Mutations in a gene,
amdT
, which affect glucose repression of amidases are described. One of these,
amdT102
, causes the acetamidase to be no longer subject to glucose repression and also affects ability to synthesize formamidase. The other,
amdT19
, results in both the formamidase and the acetamidase being subject to abnormally strong glucose repression, and also in increased maximal acetamidase activities. The dominance relationships at the
amdT
locus have been investigated. It is suggested that the
amdT
gene may play a positive role in controlling amidase synthesis.
Amino Acid Sequence Around the Catalytic Site in Glyceraldehyde-3-Phosphate Dehydrogenase from
Bacillus stearothermophilus
Authors: Bridgen J. , Harris J. I. , McDonald P. W. , Amelunxen R. E. , Kimmel J. R.
Published: January 2020

The tryptic peptide containing the active-site cysteine in glyceraldehyde-3-phosphate dehydrogenase from
Bacillus stearothermophilus
1503 was isolated after inhibition of the enzyme with
14
C-iodoacetate. The amino acid sequence of the 20-residue peptide was determined by 19 successive cycles of dansyl-Edman degradation. The sequence shows considerable homology with its counterparts from mesophilic sources but differs by the addition of Ala-His-His at the
N
-terminus and by the substitution of phenylalanine for leucine in the prototype sequence.
Some Observations of Ascospores of
Neurospora crassa
Made with a Scanning Electron Microscope
Authors: Sullivan Jerome L. , Wagner Pamela C. , DeBusk A. Gib
Published: January 2020

Scanning electron micrographs of ascospores of
Neurospora crassa
reveal two of the structures which develop during germination and outgrowth: (i) a germination pore and (ii) the probable site of initiation of hyphal cell wall synthesis.
Interactions Between Amino Acid Transport Systems in
Neurospora crassa
Authors: Sanchez S. , Martinez L. , Mora J.
Published: January 2020

Mutants of
Neurospora crassa
, selected as resistant to
l
-canavanine and
l
-thialysine, are partially deficient in the uptake of basic amino acids. Neutral amino acids completely inhibit uptake of basic amino acids, and this inhibition is dependent on the activity of a neutral amino acid permease. In contradistinction, mutants resistant to 4-methyl-
dl
-tryptophan are partially deficient in the uptake of neutral amino acids. Basic amino acids completely inhibit neutral amino acid uptake, and this inhibition is dependent on the activity of a basic amino acid permease. It is proposed that these specific transport systems compete with a general amino acid permease for some common element. The general permease is also regulated by ammonia, the amino acid pool, or both. The activity of the general permease can be eliminated phenotypically by a high concentration of glycerol or a high temperature. It is also shown that
l
-citrulline is transported by the neutral amino acid permease and by the general amino acid permease.
Differential Amino Acid Requirements for Sporulation in
Bacillus subtilis
Authors: Doering Jeffrey L. , Bott Kenneth F.
Published: January 2020

The amino acid requirements for sporulation were studied by use of auxotrophic mutants of
Bacillus subtilis
168. Cells were grown to T
0
in medium containing the test amino acid and were then transferred to a minimal medium lacking that amino acid. Omission of leucine caused no reduction in sporulation. Omission of methionine, lysine, and phenylalanine appeared to cause reduced levels of sporulation, and sporulation was completely inhibited when isoleucine, tryptophan, and threonine were omitted. The amino acids in this third class showed a sequence of requirements, with tryptophan required earlier than isoleucine, which in turn was required earlier in the sporulation process than threonine. Isoleucine omission did not affect the early sporulation functions of extracellular protease formation or septum formation, but prevented the increased levels of protein synthesis and oxygen consumption that normally accompany early sporulation stages. Isoleucine did not appear to be metabolized to other compounds in significant amounts during sporulation. The role of isoleucine in the sporulation process remains unclear.
Variable Ammonia Production Among Smooth and Rough Strains of
Pseudomonas pseudomallei
: Resemblance to Bacteriocin Production
Authors: Rogul Marvin , Carr Susan R.
Published: January 2020

The colonial morphology of some strains of
Pseudomonas pseudomallei
was correlated with certain biochemical and physiological traits. After 3 days of growth on Wahba or heart infusion agars, smooth-colony strains generated toxic amounts of ammonia. Under the same conditions, the rough strains simultaneously produced oxalic acid which decreased the inhibitory concentration of ammonia. The ammonia-ammonium concentrations in smooth cultures exhibited certain bacteriocin-like characteristics. An unusually stable, smooth strain (strain 165) was chosen to compare and emphasize any differences with typical, rough strain 7815. Three-day-old smooth cultures grown on Wahba agar containing 3% (w/v) glycerol demonstrated ammonia toxicity. The substitution of glucose for glycerol completely obviated this toxicity. In highly aerated Wahba broth containing glucose, the amount of ammonia found in strain 165 smooth cultures and the amount of oxalic acid found in strain 7815 rough cultures were greatly reduced. In Difco nitrate broth smooth strain 165 did not form gas, and it reduced nitrate to nitrite only. Strain 7815 produced a gas and reduced both nitrate and nitrite.
Evidence Against the Presence of 3′, 5′-Cyclic Adenosine Monophosphate and Relevant Enzymes in
Lactobacillus plantarum
Authors: Sahyoun N. , Durr I. F.
Published: January 2020

Analysis of cells of
Lactobacillus plantarum
, starved or undergoing induction, showed no 3′, 5′-cyclic adenosine monophosphate (cAMP). Neither adenyl cyclase nor 3′, 5′-cAMP phosphodiesterase was detected in extracts. Extracts of
L. plantarum
did not inhibit these two enzymes of
Escherichia coli
K-12, strain W1435. Incubation of adenosine triphosphate (ATP)-
U
-
14
C
with cells or various cell-free fractions of
L. plantarum
did not produce labeled 3′, 5′-cAMP. Of various 3′, 5′-cyclic and acyclic nucleotides tested, only 3′, 5′-cAMP, ATP, and yeast adenylic acid stimulated
l
-arabinose isomerase. Yeast adenylic acid was two to four times as effective as 3′, 5′-cAMP or ATP. 2′, 3′-cAMP was not effective.
Reconstitution of
Micrococcus lysodeikticus
Reduced Nicotinamide Adenine Dinucleotide and
l
-Malate Dehydrogenases with Dehydrogenase-Depleted Membrane Residues: a Basis for Restoration of Oxidase Actitivies
Authors: Eisenberg Robert C.
Published: January 2020

Deoxycholate disruption of
Micrococcus lysodeikticus
protoplast membranes resulted in solubilization of both
l
-malate and reduced nicotinamide adenine dinucleotide (NADH) dehydrogenase enzymes (substrate: 2,6-dichlorophenolindophenol oxidoreductases). Insoluble residues contained cytochromes of the
b, c
, and
a
type. Solubilized dehydrogenases were reconstituted with insoluble residues by treatment of disrupted membranes with magnesium ions. Most of the solubilized
l
-malate and NADH dehydrogenase activities were precipitated by magnesium ions independent of enzyme reconstitution with insoluble residues. Reconstituted dehydrogenases explained the mechanism for restoration of disrupted
l
-malate and NADH oxidase activities (4). Black light irradiation inhibited oxidase activities of both native and reconstituted membranes. These irradiated membrane oxidases were partially restored by exogenous napthoquinones [K
2(20)
and K
2(50)
] but not by CoQ
(6)
. Reconstitution experiments showed that native membrane napthoquinone was retained in the insoluble residues of deoxycholate-disrupted membranes.
Hydrolysis of α
s, 1
-Casein B by
Streptococcus lactis
Membrane Proteinase
Authors: Sorrells K. M. , Cowman R. A. , Swaisgood H. E.
Published: January 2020

The membrane-associated proteinase of
Streptococcus lactis
strain 3 hydrolyzed α
s, 1
-casein B into 11 peptide fragments. Eight of the 11 peptides were purified and partially characterized. Each peptide contained several, but not all six, essential amino acids required for growth. The culture was able to utilize one peptide as the sole source for the essential amino acid leucine. Leucine, serine, valine, and glycine were found to be NH
2
-terminal residues. Two of the peptides were phosphopeptides. The data support the functional role of the membrane-associated proteinase as being involved in the initial breakdown of proteins to peptides.
Properties of Phosphoribulokinase from
Thiobacillus neapolitanus
Authors: MacElroy Robert D. , Mack Henry M. , Johnson Emmett J.
Published: January 2020

Partially purified preparations of ribulose-5-phosphate kinase (specific activity, 50 to 125 μmoles per min per mg of protein) were employed in a series of kinetic experiments in the presence of several concentrations of H
+
, Mg
2+
, adenosine triphosphate (ATP), and phosphoenolpyruvate (PEP). The
p
H optimum of the enzyme was found to be 7.9; at this
p
H and above, response of the enzyme to variations in ATP concentration was hyperbolic, exhibiting a
K
m
of 7 × 10
−4
m
ATP. At
p
H values below the optimum the response to ATP was sigmoidal, as it was throughout the entire
p
H range in the presence of PEP at a concentration greater than 5 × 10
−4
m
. In the presence of PEP the
p
H optimum shifted to
p
H 8.4. In contrast, phosphoribulokinase from spinach exhibited hyperbolic responses throughout its
p
H range with no inhibition caused by PEP.
Thiobacillus neapolitanus
phosphoribulokinase was inhibited by PEP in a sigmoidal manner; however, in the presence of suboptimal concentrations of Mg
2+
the addition of PEP caused significant stimulation of activity. It is postulated that the enzyme consists of interacting subunits with several sites on the enzyme for binding ATP and with several separate sites binding PEP. It is suggested that PEP functions as a regulator of CO
2
fixation when the organism is under conditions of unlimited concentrations of substrate and CO
2
.
Lipid Composition of
Mycoplasma neurolyticum
Authors: Smith Paul F.
Published: January 2020

The total lipid content of
Mycoplasma neurolyticum
comprises about 14% of the dry weight of the organisms and is about equally distributed between the phospholipid and the neutral-glycolipid fractions. The neutral lipids were identified as triglycerides, diglycerides, and cholesterol. The glycolipid fraction contained 1-
O
-β-glucopyranosyl-
d
-2,3-diglyceride and 1-[
O
-β-
d
-glycopyranosyl-(1→6)-
O
-β-
d
-glucopyranosyl]-
d
-2,3-diglyceride. The latter lipid is structurally identical to the diglucosyl diglyceride which occurs in
Staphylococcus aureus
. The phospholipids of the organism consist of a fully acylated glycerophosphoryl-glycerophosphoryl glycerol, phosphatidic acid, diphosphatidyl glycerol, phosphatidyl glycerol, and amino acyl esters of phosphatidyl glycerol. Phosphatidic acid and phosphatidyl glycerol account for greater than 90% of the phospholipids of organisms in the exponential phase of growth. The predominant fatty acids found in all of the acyl lipids were palmitic, stearic, and oleic acids.
Development of Streptococcal L-Form Colonies
Authors: Bibel David J. , Lawson John W.
Published: January 2020

The development and architecture of L-form agar colonies produced from protoplasts and L-phase bodies were studied by both light and scanning electron microscopy. Agar blocks containing L-phase microcolonies of group A
Streptococcus
strains ADA and GL8 and group D
Streptococcus
strain F24 as well as longitudinal sections of mature colonies were used as samples. Initially, granules of about 0.5 μm in diameter were produced by multiple condensation and fragmentation of protoplasts and large bodies. Surface growth by granules ensued and infiltration into agar occurred only after 10 to 11 hr of incubation at 37 C. Club-shaped granules were noted and division seemed to take place by simple fission. The configuration of large bodies and granules in mature colonies suggested budding as another means of replication. Acellular spaces inside the colonies appeared to have been formed by lysis of large bodies or by the envelopment of space by the extending growth of minute granules. Whereas no significant strain variation was noted in colonies of less than 24 hr of incubation, fully mature colonies were differentiated on uniform media.
Occurrence of 3-
O
-(β-
d
-Glucopyranosyluronic Acid)-
d
-Galactose in the Capsular Polysaccharide of
Klebsiella
K-Type 20
Authors: Choy Y. M. , Dutton G. G. S.
Published: January 2020

Partial hydrolysis and methylation studies have been used to show that the capsular polysaccharide of
Klebsiella
K-type 20 is composed of a main chain of
d
-mannose and
d
-galactose units with the aldobiouronic acid attached as a side chain to
d
-mannose
Loss of Deoxyribonucleic Acid-Thymine During Thymine Starvation of
Escherichia coli
Authors: Breitman T. R. , Maury P. B. , Toal J. N.
Published: January 2020

A substantial loss of deoxyribonucleic acid-thymine occurs during thymine starvation of several thymine auxotrophs derived from
Escherichia coli
strains B, 15, and K-12.
A Salt-Inhibited Cytochrome
c
Reductase Obtained from the Moderately Halophilic Bacterium,
Micrococcus halodenitrificans
Authors: Miller James E. , Hochstein Lawrence I.
Published: January 2020

A membrane-bound cytochrome
c
reductase from
Micrococcus halodenitrificans
was inhibited by NaCl at concentrations as low as 0.05
m
. The inhibition was competitive with respect to cytochrome
c
and noncompetitive with respect to reduced nicotinamide adenine dinucleotide. Thus the effect of NaCl was to increase the apparent
K
m
of the enzyme for cytochrome
c
and not to inhibit the intrinsic activity of the enzyme.
Ethambutol-Mediated Alterations in Ribonucleic Acid Components of
Mycobacterium smegmatis
Authors: Bacalao J. , Rieber M.
Published: January 2020

Polyacrylamide gel electrophoresis of ribonucleic acid (RNA) components from
Mycobacterium smegmatis
exposed to ethambutol shows that the early effect of the drug produces a selective alteration of some RNA species, suggestive of a noncoordinate control of RNA metabolism.
Importance of Facilitated Diffusion for Effective Utilization of Glycerol by
Escherichia coli
Authors: Richey D. P. , Lin E. C. C.
Published: January 2020

Wild-type
Escherichia coli
possesses an inducible permeation system which catalyzes facilitated diffusion of glycerol into the cell. A spectrophotometric method can be used to assess the presence of this mechanism. The structural gene for the facilitator (
glpF
) and the structural gene for glycerol kinase (
glpK
) apparently belong to a single operon. The
glpF
+
allele permits effective glycerol utilization by the cells, and, at millimolar concentrations of glycerol, cells carrying the
glpF
+
allele grow much faster than
glpF
genotypes. Although the glycerol-scavenging power of the cell depends both on the facilitated entry of the substrate and its subsequent trapping by an adenosine triphosphate-dependent phosphorylation, the two gene products, the facilitator and kinase, function independently. Wild-type
Shigella flexneri
appears to be
glpK
+
but
glpF
. This organism grows slowly in media at low concentrations of glycerol. When the
glpF
+
and
glpK
+
alleles of
E. coli
are inserted into the
S. flexneri
genome by transduction, the hybrid strain grows rapidly in low glycerol medium. Vice versa, when the
glpF
and
glpK
+
alleles of
S. flexneri
are incorporated into
E. coli
, the hybrid strain grows slowly in low glycerol medium.
Bacteriocin Production by Transformable Group H Streptococci
Authors: Schlegel Richard , Slade Hutton D.
Published: January 2020

Group H streptococci (strain Challis) which are competent for transformation release a bacteriocin into liquid medium which is bacteriocidal for another group H streptococcus (strain Wicky). The streptocin (STH
1
) is resistant to treatment with deoxyribonuclease and ribonuclease but is sensitive to trypsin, phospholipase C, and alkaline phosphatase. Such enzyme sensitivity experiments indicate that the bacteriocin may be a complex molecule (protein and lipid) containing phosphate groups essential for activity. STH
1
, which is readily distinguishable from competence factor and bacteriophage activity, appears to have no role in the initiation of the competent state in strain Wicky. The presence of this factor in Challis culture supernatant fluids indicates that a reevaluation of earlier studies performed with the Challis-Wicky transformation system may be necessary.
Deletion and Complementation Analysis of the Biotin Gene Cluster of
Escherichia coli
Authors: Cleary Paul P. , Campbell Allan
Published: January 2020

Genetic deletions that terminate within the cluster of genes needed for biotin biosynthesis in
Escherichia coli
have been isolated and mapped by transduction with phages lambda and P1. These deletions order the point mutations in each of the five genes. Mutations causing biotin dependence were incorporated into λ
pbio
transducing phages. New
bio
−
mutations were induced by exposure of λ
pbio
particles to ultraviolet light. Tests of complementation between such
bio
−
pbio
particles and
bio
−
mutant cells divide the
bio
−
mutations into five cistrons:
bioA, bioB, bioF, bioC
, and
bioD
. Certain
bioA
and
bioF
mutations exhibit intragenic complementation, suggesting that these genes determine enzymes composed of identical subunits.
Molecular Studies on Entry Exclusion in
Escherichia coli
Minicells
Authors: Sheehy Ronald J. , Orr Clifton , Curtiss Roy
Published: January 2020

Minicells produced by abnormal cell division in a strain of
Escherichia coli
(K-12) have been employed here to investigate the phenomenon of “entry exclusion.” When purified minicells from strains containing F′ or R factors, or both, are mated with radioactive thymidine-labeled Hfr or R
+
donors, the recipient minicells can be conveniently separated from normal-sized donors following mating, and the products of conjugation can be analyzed in the absence of donors and of further growth of the recipients. Transmissible plasmids or episomes are transferred less efficiently to purified minicells derived from strains carrying similar or related elements than to strains without them. Measurement of deoxyribonucleic acid (DNA) degradation and determination of weight-average molecular weights following transfer indicate that degradation of transferred DNA or transfer of smaller pieces cannot account for the comparative reduction in transfer to entry-excluding recipients. Therefore, we conclude that entry exclusion operates to prevent the physical entry of DNA into recipients expressing the exclusion phenotype. The R-produced repressor (product of the
drd
+
gene), which represses fertility (i.e., ability to act as donor), reduces exclusion mediated by R or F factor, or both, in matings between strains carrying homologous elements. Furthermore, the data suggest that the presence of the F pilus or F-like R pilus on recipient cells ensures maximum expression of the exclusion phenotype but is not essential for its expression. In contrast to previous suggestions, we found no evidence for a reduction of entry exclusion attributable to the DNA temperature-sensitive chromosomal mutation
dnaB
(TS).
Amino Sugar Assimilation byEscherichia coli
Authors: Rolls James P. , Shuster C. W.
Published: January 2020

The carbon skeleton of glucose is extensively randomized during conversion to cell wall glucosamine byEscherichia coliK-12. Exogenous glucosamine-1-14Cis selectively oxidized, and isotope incorporation into cellular glucosamine is greatly diluted during assimilation. A mutant unable to grow withN-acetylglucosamine as a carbon and energy source was isolated fromE. coliK-12. This mutant was found to be defective in glucosamine-6-phosphate deaminase. Glucosamine-1-14CandN-acetylglucosamine-1-14Cwere assimilated during the growth of mutant cultures without degradation or carbon randomization. Assimilated isotopic carbon resided entirely in cell wall glucosamine and muramic acid. Some isotope dilution occurred from biosynthesis, but at high concentrations (0.2 mm) of addedN-acetylglucosamine nearly all cellular amino sugar was derived from the exogenous source. Growth of the mutant was inhibited with 1 mmN-acetylglucosamine.
Characterization of
l
-Leucine-Induced Germination of
Trichophyton mentagrophytes
Microconidia
Authors: Hashimoto Tadayo , Wu C. D. R. , Blumenthal H. J.
Published: January 2020

l
-Leucine and several amino acids were effective germination inducers of microconidia of
Trichophyton mentagrophytes
. During germination, phase-darkening and swelling occurred concomitantly with the loss of resistance to heat and stain, reduction of dry weight and specific gravity, and development of active glucose utilization. Germination induced by
l
-leucine was significantly stimulated by a pretreatment of the spores with sublethal doses of heat. No nucleosides or nucleotides were stimulatory to the
l
-leucine-induced germination of the microconidia.
d
-Leucine was almost an equally effective germinant as its
l
form. No carbohydrates, salts, vitamins, or other compounds tested induced germination of the fungus spore. Other factors that affected
l
-leucine-induced germination of the microconidia included the concentration of leucine, the inoculum size of the spores, temperature, and
p
H. The anaerobic condition and the presence or absence of carbon dioxide had no significant effects on the germination. Short germ tubes usually developed when the germinated spores were further incubated either in the presence or absence of
l
-leucine. The cytological study of the germinating microconidia revealed that the fragmentation of lipid granules was the major structural change associated with the germination.
Different Arginine Transfer Ribonucleic Acid Species Prevalent in Shaken and Unshaken Cultures of
Neurospora
Authors: Nazario M.
Published: January 2020

When the arginyl-transfer ribonucleic acid (tRNA) species isolated from unshaken and from shaken cultures of
Neurospora
were compared by co-chromatography, a marked change in the relative abundance of the two main tRNA
arg
species was found. The two arginine tRNA species had different codon responses in ribosome binding assays. The tRNA
arg
eluting first (prevalent in shaken cultures) bound strongly to polyadenylic-guanylic acid [poly(A,G)] and to a lesser extent to polycytidylic-guanylic-adenylic acid [poly(C,G,A)]. The second tRNA
arg
species (prevalent in unshaken cultures) bound to poly(C,G,A) but not to poly(A, G). The possible significance of these observations is briefly discussed. Several modifications that improve the yield of tRNA from
Neurospora
were introduced in a standard isolation procedure.
Effect of Oxygen on Several Enzymes Involved in the Aerobic and Anaerobic Utilization of Glucose inEscherichia coli
Authors: Thomas Annette D. , Doelle H. W. , Westwood A. W. , Gordon G. L.
Published: January 2020

By using the continuous culture technique, the transition from aerobiosis to anaerobiosis and its effect on a number of enzymes has been investigated inEscherichia coliK-12. A decrease in the oxygen partial pressure below 28.0 mm of Hg resulted firstly in an increase of the respiratory enzymes (reduced nicotinamide adenine dinucleotide [NADH] oxidase, 2.53-fold; succinic dehydrogenase, 1.4-fold; cytochromeb1, 3.91-fold; and cytochromea2, 2.45-fold) before the electron transport system gradually collapsed as cytochromea2, followed by cytochromeb1, succinic dehydrogenase, and finally NADH oxidase decreased in activity. The change from respiration to fermentation was initiated well before the oxygen tension reached zero by the increase in levels of fructose diphosphate-aldolase, glucose 6-phosphate, and 6-phosphogluconate dehydrogenases and a decrease in 2-oxoglutarate dehydrogenase. Whem the dissolved oxygen tension reached zero, dry weight and CO2formation together with isocitrate dehydrogenase decreased, whereas acid production and phosphofructokinase synthesis started to increase. Enzymatic investigations revealed that the kinetics of the enzyme phosphofructokinase from strict aerobic cultures (6.9 ppm oxygen in solution) was adenosine triphosphate (ATP)-insensitive, whereas the same enzyme from anaerobic cultures was ATP-sensitive. A mechanism is proposed for the change from aerobiosis to anaerobiosis together with the occurring change in glucose regulation.
Ubiquinone Function in
Neurospora crassa
Authors: Drabikowska Alicja K. , Kruszewska Anna
Published: January 2020

Mitochondria of cytoplasmic respiratory mutants [mi-1] (poky) and [mi-4] contain about a fourfold molar excess of ubiquinone as compared to the wild-type strain of
Neurospora crassa
. In the wild type and [mi-1] cultures the concentration of ubiquinone remains constant during the exponential and stationary phase of growth. In [mi-4] cultures it markedly decreases in the stationary phase. The reduction of ubiquinone by substrates is approximately the same in the three strains tested and amounts 60 to 70% of total ubiquinone present in mitochondria, independent of its absolute amount. The reduction of ubiquinone on addition of substrates is accompanied by the similar reduction of cytochrome
c
. These indicate that mitochondrial ubiquinone and cytochrome
c
are involved in processes of oxidation in
Neurospora
and that ubiquinone belongs mainly if not entirely to the cytochrome system of electron transport in these strains.
Lipids of
Thermoplasma acidophilum
Authors: Langworthy Thomas A. , Smith Paul F. , Mayberry William R.
Published: January 2020

Cells of
Thermoplasma acidophilum
contain about 3% total lipid on a dry weight basis. Total lipid was found to contain 17.5% neutral lipid, 25.1% glycolipid, and 56.6% phospholipid by chromatography on silicic acid. The lipids contain almost no fatty acid ester groups but appear to have long-chain alkyl groups in ether linkages to glycerol. The phospholipid fraction includes a major component which represents about 80% of the lipid phosphorus and 46% of the total lipids. We believe this component to be a long-chain isopranol glycerol diether analogue of glycerolphosphoryl monoglycosyl diglyceride. The glycolipids appear to contain isopranol diether analogues. Several components of the complex, neutral lipid fraction have been identified as hydrocarbons, vitamin K
2
-7, and isopranol glycerol diether analogues. Sterols are present in the neutral lipids but do not appear to be synthesized by the organism.