bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of Oxygen and Glucose on Energy Metabolism and Dimorphism of
Mucor genevensis
Grown in Continuous Culture: Reversibility of Yeast-Mycelium Conversion
Authors: Rogers P. J. , Clark-Walker G. D. , Stewart P. R.
Published: January 2020

Mucor genevensis
was grown in both glucose-limited and glucose-excess continuous cultures over a range of dissolved oxygen concentrations (<0.1 to 25 μM) to determine the effects of glucose and the influence of metabolic mode (fermentative versus oxidative) on dimorphic transformations in this organism. The extent of differentiation between yeast and mycelial phases has been correlated with physiological and biochemical parameters of the cultures. Under glucose limitation, oxidative metabolism increased as the dissolved oxygen concentration increased, and this paralleled the increase in the proportion of the mycelial phase in the cultures. Filamentous growth and oxidative metabolism were both inhibited by glucose even though mitochondrial development was only slightly repressed. However, the presence of chloramphenicol in glucose-limited aerobic cultures inhibited mitochondrial respiratory development but did not induce yeast-like growth, indicating that oxidative metabolism is not essential for mycelial development. Once mycelial cultures had been established under aerobic, glucose-limited conditions, subsequent reversal to anaerobic conditions or treatment with chloramphenicol caused only a limited reversal (<35%) to the yeast-like form. Glucose, however, induced a complete reversion to yeast-like form. It is concluded that glucose is the most important single culture factor determining the morphological status of
M. genevensis
; mitochondrial development and the functional oxidative capacities of the cell appear to be less important factors in the differentiation process.
Characterization of Dimorphism in
Cladosporium werneckii
Authors: Hardcastle Ronald V. , Szaniszlo Paul J.
Published: January 2020

Yeast forms of the dimorphic fungus
Cladosporium werneckii
grow by polar budding and yield a homogeneous yeast phase when cultured at 21 C in an agitated sucrose-salts medium (Czapek-Dox broth). Yeast extract enrichment of such a yeast phase consisting of 10
4
yeasts per ml induces a quantitative conversion of the yeasts to true hyphae. This conversion is not mediated by a transition cell and is often attended by capsule formation. When 10
5
or 10
6
yeasts per ml receive enrichment, a nonquantitative conversion to moniliform hyphae is effected and no capsule formation is observed. Rapid agitation compared to slow agitation or stationary incubation of the nutritionally mediated conversion cultures greatly accelerates the production of lateral hyphal buds or their yeast progenies. These cells appear incapable of undergoing nutritional conversion to hyphae, but instead must grow for several generations in the unenriched sucrose-salts medium to restore conversion competence. Temperature shifts affect directly the morphology and morphogenesis of the yeast in unenriched medium; at 17 C yeasts are smaller and more ovoid than at 21 C, and at 30 C marked conversion of yeasts to moniliform hyphae occurs. A methodology employing the Coulter counter and Coulter channelizer provides evidence that direct correlations do not always exist between the optimum conditions for the growth of
C. werneckii
and the optimum conditions for its yeast-to-mold conversion.
Mutagenesis by Mutator Gene
mutH1
in Continuous Cultures of
Escherichia coli
Authors: Nestmann Earle R. , Hill Ruth F.
Published: January 2020

Mutability as a function of growth rate was examined in bacterial strains containing mutator gene
mutH1
. The rate of mutation to bacteriophage T5 resistance was found to be proportional to rate of growth in glucose-limited chemostat cultures. This finding supports the hypothesis that the mutator
mutH1
gene product increases the error frequency during deoxyribonucleic acid replication.
Mechanism of α Factor Biosynthesis in
Saccharomyces cerevisiae
Authors: Scherer Günther , Haag Georg , Duntze Wolfgang
Published: January 2020

The biosynthesis of α factor, a mating-type-specific regulatory oligopeptide which is secreted by
Saccharomyces cerevisiae
cells of α mating type, was studied. In batch cultures only small amounts of the peptide were synthesized during the exponential growth phase. During the stationary phase, α factor was produced at a constant rate and accumulated in the culture medium. Inhibition of translation in wild-type cells by cycloheximide, or in mutant strains under conditions which blocked protein or ribonucleic acid (RNA) synthesis completely inhibited the production of α factor. These results indicate that the factor is produced by ribosomal translation of a specific messenger RNA and not by an extraribosomal mechanism of peptide synthesis.
Purification and Characterization of
Streptomyces
Sialidases
Authors: Kunimoto Setsuko , Aoyagi Takaaki , Takeuchi Tomio , Umezawa Hamao
Published: January 2020

Some strains of
Streptomyces
produce sialidases. Two sialidases were purified over 1,000-fold from a culture filtrate of two
Streptomyces
species. They had the same properties in molecular weight, behavior to ions and other reagents, and substrate specificity. They showed very small differences in kinetic properties, pH optima, and heat stability. These
Streptomyces
sialidases differed markedly from
Clostridium perfringens
sialidase in molecular weight,
p
-chloromercuribenzoate sensitivity, and substrate specificity. Approximate molecular weights of the sialidases from
Streptomyces
and
C. perfringens
were 32,000 and 57,000, respectively.
p
-Chloromercuribenzoate (10
−3
M) caused complete inhibition of
C. perfringens
sialidase but not of
Streptomyces
sialidases.
Genetic and Biochemical Studies on Cell-Bound α-Amylase in
Bacillus subtilis
Marburg
Authors: Nagata Yoshiho , Yamaguchi Kazuo , Maruo Bunji
Published: January 2020

A small but significant amount of α-amylase activity was detected in the cells of
Bacillus subtilis
Marburg. The cell-associated activity was almost constant regardless of the level of extracellular α-amylase activity. The cell-bound amylase activity could be separated into three components, upon Sephadex G-75 chromatography, referred to as components A, B, and C. Component C showed the same properties as the extracellular α-amylases so far examined. Component A had a molecular weight greater than 70,000, as judged from the elution position on Sephadex G-75, and became smaller upon treatment with trypsin but was still larger than that of component C. An α-amylase mutant that lacked extracellular α-amylase completely because of a mutation within the structural gene of the enzyme was found to lose all three cell-bound amylase components simultaneously. These data suggest strongly that the cell-bound amylase components are precursors of the extracellular α-amylase and that the α-amylase of this organism is produced under the direction of the same gene whether the enzyme is within or outside the cell.
Trehalose Metabolism by
Bacillus popilliae
Authors: Bhumiratana Amaret , Anderson Richard L. , Costilow Ralph N.
Published: January 2020

Trehalose was found to be utilized more readily than glucose for the growth of
Bacillus popilliae
NRRL B-2309MC. The pathway of degradation of trehalose was elucidated and found to differ from that reported for other organisms. Trehalase and trehalose phosphorylase activities could not be detected. Rather, trehalose was found to undergo phosphoenolpyruvate (PEP)-dependent phosphorylation, and the resulting trehalose 6-phosphate was cleaved by a phosphotrehalase to equimolar amounts of glucose and glucose 6-phosphate. The phosphotrehalase was purified 34-fold and shown to have a pH optimum of 6.5 to 7.0 and a

K
m

for trehalose 6-phosphate of 1.8 mM. A mutant missing the phosphotrehalase failed to grow on trehalose but grew normally on other sugars. The mutant accumulated [
14
C]trehalose as [
14
C]trehalose 6-phosphate. Phosphorylation of trehalose by dialyzed extracts was at least 25 times faster with PEP than with adenosine 5′-triphosphate, and the phosphorylation activity was associated primarily with the particulate fraction. These data and the results of studies of [
14
C]trehalose uptake suggest that trehalose is transported into the cell as trehalose 6-phosphate by a PEP:sugar phosphotransferase system. Cell extracts of other strains of
B. popilliae
were also found to produce [
14
C]sugar phosphate from [
14
C]trehalose and to have phosphotrehalase activity.
Genetic Mapping of the Locus for Detergent-Resistant Phospholipase A (
pldA
) in
Escherichia coli
K-12
Authors: Abe Mihoko , Okamoto Nakako , Doi Osamu , Nojima Shoshichi
Published: January 2020

An
Escherichia coli
K-12 mutant deficient for detergent-resistant (DR) phospholipase A, a principal enzyme catalyzing the first step in phospholipid degradation, was characterized genetically. The mutation was found to affect the locus
pldA
(phospholipid degradation), which is cotransducible both with
ilv
and
metE
at a frequencies of 13 and 78%, respectively, and shown to lie between the
ilv
and
metE
loci on the
E. coli
chromosome. DR phospholipase A
1
and A
2
activities were simultaneously transduced with
pldA
+
by phage P1; therefore it is proposed that DR phospholipase A has both activities.
L-Form Induction, Morphology, and Development in Two Related Strains ofErysipelothrix rhusiopathiae
Authors: Pachas Willy N. , Currid Victoria R.
Published: January 2020

Two related strains ofErysipelothrix rhusiopathiae, one the parent and the other an L-form revertant, were studied for their propensity or ability to produce L-forms under the influence of penicillin. The parent strain produced L-forms in nutrient solid media in an osmolarity range between 0.85 and 5.0% NaCl concentration whereas the revertant strain did so between 0.5 and 3.0% NaCl concentration. When various hyperosmolar media were tried without penicillin, recovery of L-forms from the revertant strain was optimal at a salt concentration of 2.0%, whereas the parent strain occasionally produced a few L-forms on 3.0% salt medium only. The process of penicillin-induced transformation from bacteria to L-form followed an unusual morphological sequence, beginning with beading of the bacterial body, followed by disintegration into granules from which the L-form colony derived. No large bodies were seen during the initial process of L-form induction, but they evolved later from the original granules and had the potential to reproduce L-type growth. The spontaneous development of L-forms in hyperosmolar media had a different morphological sequence starting with elongation of the bacteria into filaments which later developed polar and central dilatations from which granules and L-type growth developed. The differences in biological behavior between these related bacterial strains suggest that the revertant strain developed new properties, probably of genetic origin. Consequently, the assumption that L-forms revert to the “parent” bacteria may not always be justified. It can be made only after the biological properties of the parent and the revertant organisms have been properly identified.
Enrichment of Mutants Lacking the Phosphoenolpyruvate-Dependent Phosphotransferase System of
Vibrio parahaemolyticus
by Screening with Methyl-α-
d
-Glucoside
Authors: Matsumoto Kazuko , Iuchi Shiro , Fujisawa Asako , Tanaka Shuji
Published: January 2020

Screening with methyl-α-
d
-glucoside was an efficient procedure for enrichment of mutants lacking the glucose transport system and of the pleiotropic mutants lacking the phosphoenolpyruvate-dependent phosphotransferase system in
Vibrio parahaemolyticus
.
Isolation of Host-Dependent and Nonparasitic Mutants of the Facultative Parasitic
Bdellovibrio
UKi2
Authors: Varon Mazal , Dickbuch Sarah , Shilo Moshe
Published: January 2020

Obligate host-dependent and nonparasitic mutants were isolated from a facultative parasitic
Bdellovibrio
strain. Thus it is possible to separate host-dependency from the ability to parasitize in bdellovibrios.
Limiting Nutrients During Mating as a Means of Increasing Recombinant Recovery in Crosses of
Nocardia erythropolis
Authors: Adams James N. , Adams Margie M.
Published: January 2020

Minimal medium supplemented with sub-optimal levels of parental auxotrophic requirements increases recombinant recovery from matings of
Nocardia erythropolis
more than 500-fold when compared with nutrient agar matings.
Lipophilic Proteins of Mitochondria from Microaerobic and Aerobic Continuous Cultures of
Saccharomyces cerevisiae
Authors: Rogers P. J. , Stewart P. R.
Published: January 2020

Products of the mitochondrial protein-synthesizing system have been labeled in vivo in the presence of cycloheximide in microaerobic cells and in cells from glucose-limited and glucose-repressed aerobic continuous cultures of
Saccharomyces cerevisiae
. Lipophilic proteins were extracted from labeled mitochondrial membranes with aqueous methanol and neutral and acidic chloroform-methanol solvents. In glucose-limited aerobic and microaerobic cells, about half of the total mitochondrial products were soluble in organic solvents; in contrast, almost all of the labeled products were extracted from glucose-repressed mitochondria. Only trace amounts of labeled product were formed in mitochondrial membranes of a petite mutant. Lipophilic proteins were examined by polyacrylamide gel electrophoresis under dissociating conditions. Most of the label was associated with components of apparent molecular weights 12,000, 14,000 and 16,000. The relative proportions of these species in mitochondrial membranes are dependent on the concentrations of oxygen and glucose in which the cells are grown.
Genetic Mapping in
Bacillus subtilis
by 5-Bromouracil Sensitization to Ultraviolet Inactivation of Transforming Activities
Authors: Matsumoto Kouji , Shibata Takehiko , Saito Hiuga
Published: January 2020

A new method for chromosome mapping of
Bacillus subtilis
Marburg is presented which is based on the sensitization to ultraviolet irradiation of transforming deoxyribonucleic acid that has incorporated 5-bromouracil instead of thymine. Deoxyribonucleic acid was extracted at intervals from the outgrowing spores of a thymine-requiring mutant incubated with 5-bromodeoxyuridine and subjected to a definite dose of ultraviolet irradiation. The residual activities of various genetic markers were assayed by transformation. The marker activity of deoxyribonucleic acid that had incorporated 5-bromodeoxyuridine was approximately 10 times as sensitive to ultraviolet irradiation as that of normal deoxyribonucleic acid. The markers proximal to the replication origin were sensitized at earlier times of outgrowth than distal markers. The chromosome replication in outgrowing spores was sufficiently synchronous and allowed the definite determination of when a marker became sensitized by incorporation of 5-bromodeoxyuridine. The time, designated “sensitization time,” was estimated by plotting the logarithmic values of relative residual activities versus incubation times. The map constructed with sensitization times as a measurement showed good agreement with those constructed by other methods. The replication of the chromosome under the described conditions appeared to occur in the following marker order: (
purA, hisA
)-(
purB
)-(
thr, pyrA
)-(
metC
)-(
leuA
)-(
lys, trpC, metB
).
Size of the Chromosome of
Pseudomonas aeruginosa
PAO
Authors: Pemberton J. M.
Published: January 2020

Electron microscope examination and velocity sedimentation analysis of the deoxyribonucleic acid released from
Pseudomonas aeruginosa
spheroplasts indicate that this organism carries the bulk of its genetic determinants in a single duplex deoxyribonucleic acid molecule having a molecular mass of 2.1 × 10
9
daltons.
Participation of Lipopolysaccharide Genes in the Determination of the Enterobacterial Common Antigen: Analysis in
Salmonella
Groups B and C
1
Authors: Mäkelä P. Helena , Mayer H.
Published: January 2020

The enterobacterial common antigen (CA) is present in salmonellae of groups B (
S. typhimurium
) and C
1
(
S. montevideo
). Mutation at the
rfe
gene(s), which is required for the biosynthesis of O side chains of the lipopolysaccharide in group C
1
(S-6, 7) but not in group B (S-4, 12), destroys the capacity of the bacteria to synthesize CA. When such mutated group C
1
rfe
genes (C-
rfe
−
) were introduced into group B strains, the hybrids also became CA
−
and could be restored to CA
+
by introduction of either C-
rfe
+
or B-
rfe
+
(corresponding genetic region in group B). This indicated the presence of genes for CA synthesis at the
rfe
site in both groups B and C
1
. In
rfe
−
mutants of group C
1
, which were rough and CA
−
, the CA
+
phenotype could be restored by replacing the
rfe
−
gene(s) with C-
rfe
+
. In contrast, B-
rfe
+
was able to support the synthesis of trace amounts of CA only, although it was sufficient to restore their ability to synthesize the S-6, 7 side chain of the lipopolysaccharide. Corresponding hybrids (B-
rfe
+
, C-
rfb
+
or C-
rfb
−
) were constructed by introducing the C-
rfb
genes into a group B strain; they also showed only a trace of CA reactivity.
Bacterial Calcium Transport: Energy-Dependent Calcium Uptake by Membrane Vesicles from
Bacillus megaterium
Authors: Golub Ellis E. , Bronner Felix
Published: January 2020

Membrane vesicles capable of energy-dependent calcium uptake have been prepared from
Bacillus megaterium
cells in log-phase growth or when undergoing sporulation. The uptake is dependent on the calcium concentration and appears saturable in vesicles from cells in log-phase growth. Both ascorbate and phenazine methosulfate are needed as a source of electrons for the energy-dependent increase in calcium uptake. Addition of 8 mM sodium cyanide inhibited the energy-dependent uptake. If this calcium uptake mechanism is a component of the sporulation-specific calcium accumulation process, the latter's functional expression would appear to be inhibited during log-phase growth.
Purification and Properties of 4-Hydroxy-2-Ketopimelate Aldolase from
Acinetobacter
Authors: Leung Pak-Tong , Chapman Peter J. , Dagley Stanley
Published: January 2020

The chemical synthesis of 4-hydroxy-2-ketopimelic acid is described. An aldolase that cleaves this compound to succinic semialdehyde and pyruvate has been purified from
Acinetobacter
grown at the expense of 4-hydroxyphenylacetic acid. The molecular weight of the enzyme was about 158,000 from sedimentation equilibrium data; other physical determinations gave values in reasonable agreement. The protein was globular and was dissociated in sodium dodecyl sulfate to give a species of molecular weight 25,700. The enzyme attacked both enantiomers of synthetic 4-hydroxy-2-ketopimelate and was stimulated by Mg
2+
and Mn
2+
ions.
Appearance of a γ-
d
-Glutamyl-(
l
)
Meso
-Diaminopimelate Peptidoglycan Hydrolase During Sporulation in
Bacillus sphaericus
Authors: Guinand M. , Michel G. , Tipper D. J.
Published: January 2020

Particulate preparations from sporulating cells of
Bacillus sphaericus
9602 contained an endopeptidase activity that hydrolyzed the γ-
d
-glutamyl-(
l
)
meso
-diaminopimelic acid linkages found in the spore cortical peptidoglycan of this organism. Diaminopimelic acid did not occur in the vegetative cell wall peptidoglycan, and the γ-
d
-glutamyl-
l
-lysine linkages found in this polymer were not hydrolyzed by the endopeptidase. The endopeptidase hydrolyzed (X)-
l
-alanyl-γ-
d
-glutamyl-(
l
)
meso
-diaminopimelyl(
l
)-
d
-alanyl-
d
-alanine only after removal of the terminal
d
-alanine residue. The preparations contained an acyl-
d
-alanyl-
d
-alanine carboxypeptidase I activity which converted such pentapeptides into substrates for the endopeptidase and which was inhibited 50% by 4 × 10
−7
M benzylpenicillin. This activity also hydrolyzed the analogous pentapeptide substrates containing
l
-lysine. The preparations also contained an acyl-
l
-lysyl-
d
-alanine carboxypeptidase II activity that was not active on the
meso
-diaminopimelic acid-containing analogue. Neither this activity nor the endopeptidase was inhibited by 10
−3
M benzylpenicillin. The specificities of the carboxypeptidases were consistent with the exclusive presence of
l
-lysine C-termini in the vegetative peptidoglycan and of
meso
-diaminopimelyl-
d
-alanine C-termini in the spore cortical peptidoglycan of
B. sphaericus
9602.
Inhibition of Transformation of
Bacillus subtilis by
Heavy Metals
Authors: Groves David J. , Wilson Gary A. , Young Frank E.
Published: January 2020

Mercuric ions, as well as organomercuric ions and cadmium ions, can inhibit deoxyribonucleic acid-mediated transformation in
Bacillus subtilis
168 without decreasing the viability of the total population. Differences in the inhibition of transformation by mercuric ions are identifiable on a temporal and concentration dependence basis. Sensitivity to low concentrations (9.2 × 10
−8
M) appears early in the uptake of deoxyribonucleic acid before the transformed markers have become insensitive to deoxyribonuclease. Resistance to “low concentrations” of Hg
2+
is kinetically indistinguishable from the requirement for magnesium in the transformation process. This inactivation is not reversed by the mercury-binding compound glutathione. Sensitivity to mercuric ions at a higher concentration (5.52 × 10
−7
M) occurs after the donor deoxyribonucleic acid has become insensitive to deoxyribonuclease. These complex interactions between mercuric ions and the process of transformation are discussed.
Lipoteichoic Acid Localization in Mesosomal Vesicles of
Staphylococcus aureus
Authors: Huff E. , Cole R. M. , Theodore T. S.
Published: January 2020

Mesosomal vesicles and plasma membranes of
Staphylococcus aureus
ATCC 6538P have been prepared and examined for the presence of lipoteichoic acid. Lipids were first removed by treatment with pyridine-acetic acid-butanol (22:31:100, vol/vol/vol) and chloroform-methanol (2:1, vol/vol). Subsequently, lipoteichoic acid was removed with 40% phenol in water. The lipoteichoic acid from mesosomal vesicles was characterized by (i) equimolar glycerol and phosphate, (ii) alanine upon hydrolysis (2 N NH
4
OH, 18 h, 22 C), and (iii) fatty acids, diglycerol triphosphate, glycerol monophosphate, and glycerol diphosphate upon alkaline hydrolysis (1 N NaOH, 3h, 100 C). The plasma membranes contained no lipoteichoic acid. The presence in mesosomal vesicles of 18% of the dry weight as lipoteichoic acid and its absence from plasma membranes provide the first major chemical differences between these organelles. A study of the lipoteichoic acid content in various fractions of the cell showed that the mesosomal vesicles were the major and probably the sole site for the localization of the lipoteichoic acid in these organisms. A new method for the preparation of mesosomes in increased yields is reported. A theory for the control of cell division involving lipoteichoic acid and the mesosome is proposed.
Properties of Ribosomes from
Streptomyces erythreus
and
Streptomyces griseus
Authors: Teraoka Hiroshi , Tanaka Kentaro
Published: January 2020

Ribosomes from an erythromycin-producing strain,
Streptomyces erythreus
, lacked affinity for erythromycin and were also resistant to other macrolide antibiotics (leucomycin, spiramycin, and tylosin) and to lincomycin, whereas
Streptomyces griseus
B
3
ribosomes were susceptible to all of these antibiotics.
Isolation and Characterization of Proline Peptidase Mutants of
Salmonella typhimurium
Authors: McHugh Gail Larkin , Miller Charles G.
Published: January 2020

The proline requirement of
Salmonella typhimurium
strain
proB25
can be satisfied by either of the peptides Leu-Pro or Gly-Pro-Ala. A mutant derivative of strain
proB25
isolated by penicillin selection in medium containing Leu-Pro as proline source fails to use either Leu-Pro or Gly-Pro-Ala as a source of proline. This strain is a double mutant that lacks two aminoacyl-proline-specific peptidases. One of these enzymes (peptidase Q) catalyzes the rapid hydrolysis of Leu-Pro but does not hydrolyze Gly-Pro-Ala or poly-
l
-proline. Mutations at a site (
pepQ
) near
metE
lead to loss of this activity. The other peptidase (peptidase P) catalyzes the hydrolysis of Gly-Pro-Ala and poly-
l
-proline but is only weakly active with Leu-Pro as substrate. This enzyme is similar to aminopeptidase P previously described in
Escherichia coli
(16). Mutations at a locus (
pepP
) near
serA
lead to loss of this enzyme.
Partial Purification of a Membrane-Associated Deoxyribonucleic Acid Complex from
Mycoplasma gallisepticum
Authors: Maniloff Jack , Quinlan Dennis C.
Published: January 2020

A
Mycoplasma gallisepticum
subcellular fraction (P2), which contains the deoxyribonucleic acid replication complex, can be isolated by differential centrifugation of freeze-thaw-lysed cells. The nascent deoxyribonucleic acid is released from P2 by Lubrol-WX, sodium dodecyl sulfate, Pronase, and deoxyribonuclease, but not by saponin, ribonuclease, phospholipase C, or high-frequency sonic treatment. Sonic treatment further fractionates the cell ghost and allows partial purification, on sucrose density gradients, of a deoxyribonucleic acid replication complex attached to the cells' polar membrane-bleb-infrableb structures.
Calcification of Selected Strains of
Streptococcus mutans
and
Streptococcus sanguis
Authors: Streckfuss Joseph L. , Smith Willard N. , Brown Lee R. , Campbell Marion M.
Published: January 2020

Nine strains of cariogenic
Streptococcus mutans
and two strains of
Streptococcus sanguis
were tested for their ability to form hydroxyapatite. The cells were examined by X-ray diffraction and electron microscopy for apatite crystals after growth in a synthetic calcification medium. Each of the test isolates, except for one strain of
S. sanguis
, produced intracellular mineral. Two strains of
S. mutans
formed both intra- and extracellular crystals. There was no apparent relationship between calcifiability and serotype.
Change in Properties ofPhysarum polycephalumAmoebae During Extended Culture
Authors: Adler Paul N. , Holt Charles E.
Published: January 2020

During two years of passage, several myxamoebal strains ofPhysarum polycephalumchanged with regard to their properties in crosses and plaque morphology. These changes have been correlated with increased nuclear deoxyribonucleic acid content.
Potassium Transport and the Relationship Between Intracellular Potassium Concentration and Amino Acid Uptake by Cells of a Marine Pseudomonad
Authors: Thompson John , MacLeod Robert A.
Published: January 2020

Transport of K
+
by K
+
-depleted cells of marine pseudomonad B-16 (ATCC 19855) exhibited saturation kinetics. Rb
+
inhibited both K
+
transport and the K
+
-dependent transport of α-aminoisobutyric acid (AIB) into K
+
-depleted cells of the organism in proportion to the concentration of Rb
+
in the suspending medium. Inhibition of the K
+
-dependent uptake of AIB into K
+
-depleted cells by Rb
+
could be overcome by increasing the concentration of K
+
in the medium. When AIB and K
+
were added simultaneously to a suspension of K
+
-depleted cells, the uptake of K
+
occurred immediately and rapidly, whereas the accumulation of AIB occurred only after a lag. The initial uptake rate of AIB was directly proportional to the intracellular K
+
concentration. The intracellular concentration of K
+
and AIB at their steady-state levels increased to a maximum as the Na
+
concentration in the suspending medium was increased. At Na
+
concentrations between 0.2 and 0.3 M, the molar ratio of K
+
to AIB at their intracellular steady-state concentrations was constant at 1.6. At external Na
+
concentrations less than 0.2 M, the cells maintained a relatively higher K
+
intracellular steady-state level than AIB.
Regulation of Transaminase C Synthesis in
Escherichia coli
: Conditional Leucine Auxotrophy
Authors: McGilvray Derek , Umbarger H. E.
Published: January 2020

The regulation of synthesis of the valine-alanine-α-aminobutyrate transaminase (transaminase C) was studied in
Escherichia coli
mutants lacking the branched-chain amino acid transaminase (transaminase B). An investigation was made of two strains, CU2 and CU2002, each carrying the same transaminase B lesion but exhibiting different growth responses on a medium supplemented with branched-chain amino acids. Both had the absolute isoleucine requirement characteristic of
ilvE
auxotrophs, but growth of strain CU2 was stimulated by valine, whereas that of strain CU2002 was markedly inhibited by valine. Strain CU2002 behaved like a conditional leucine auxotroph in that the inhibition by valine was reversed by leucine. Results of enzymatic studies showed that synthesis of transaminase C was repressed by valine in strain CU2002 but not in strain CU2. Inhibition by valine in strain CU2002 appears to be the combined effect of repression on transaminase C synthesis and valine-dependent feedback inhibition of α-acetohydroxy acid synthase activity, causing α-ketoisovalerate (and hence leucine) limitation. The
ilvE
markers of strains CU2 and CU2002 were each transferred by transduction to a wild-type genetical background. All
ilvE
recombinants from both crosses resembled strain CU2002 and were inhibited by valine in the presence of isoleucine. Thus, strain CU2 carries an additional lesion that allows it to grow on a medium containing isoleucine plus valine. It is concluded that conditional leucine auxotrophy is characteristic of mutants carrying an
ilvE
lesion alone.
Effect of Uncoupling Agents and Respiratory Inhibitors on the Growth of
Streptococcus agalactiae
Authors: Mickelson M. N.
Published: January 2020

2,4-Dinitrophenol, dicoumarol, carbonylcyanide,
m
-chlorophenyl-hydrazone and pentachlorophenol all depressed aerobic molar growth yields of
Streptococcus agalactiae
to values equal to, or less than, those supported by substrate level phosphorylation. When the only source of energy was from substrate phosphorylation (anaerobic growth conditions), there was also a severe depression of the molar growth yield by the same four uncoupling agents. These results indicate that the effect of these agents is to uncouple both substrate and oxidative phosphorylation in
S. agalactiae
. Amytal inhibited glucose utilization, reduced the amount of O
2
used per mole of substrate and reduced the molar cell yield to that supported by substrate phosphorylation. Atebrin inhibited the respiration rate, but final O
2
consumed per mole of substrate was unchanged, and the respiration was coupled to biosynthesis. Rotenone had no effect on respiration, substrate utilization, or on molar growth yields.
Active Transport of Biotin in
Escherichia coli
K-12
Authors: Prakash Om , Eisenberg Max A.
Published: January 2020

The transport of [
14
C]biotin into cells of a biotin prototroph,
Escherichia coli
K-12 strain Y10-1, was investigated. The vitamin taken up by the cells in this strain existed primarily in the free form. Addition of glucose enhanced the rate of uptake six- to eightfold and the steady level was reached in 2 to 3 min resulting in accumulation of biotin against a concentration gradient. The uptake showed marked dependence on temperature (Q
10
, 2.3; optimum, 37 C) and pH (optimum 6.6) and was inhibited by iodoacetate. Energy of activation for glucose-dependent uptake was calculated to be 16,200 cal per mol. The rate of biotin uptake with increasing biotin concentrations showed saturation kinetics with an apparent
K
m
and

V
max

values of 1.4 × 10
−7
M and 6.6 pmol per mg of dry cells per min respectively. The cells also accumulated biotin against a concentration gradient in the absence of added glucose, although at a much lower rate. This accumulation was much more susceptible to inhibition by azide and uncouplers of oxidative phosphorylation suggesting that the energy source was supplied through the electron-transport chain. Inhibition studies with a number of biotin analogues indicated the requirement for an intact ureido ring. The biotin uptake was inhibited in cells grown in biotin-containing medium and was shown to be the result of repression of the transport system, suggesting the control of the biotin transport.
Co-Transduction of Plasmids Mediating Resistance to Tetracycline and Chloramphenicol in
Staphylococcus aureus
Authors: Stiffler Paul W. , Sweeney Helen M. , Cohen Sidney
Published: January 2020

Independent plasmids mediating resistance either to tetracycline (Tc) or chloramphenicol (Cm) were transduced successively into
Staphylococcus aureus
strain 8325. From this doubly resistant donor strain, Tc was co-transduced with a frequency of 40 to 50% when Cm was selected. Co-transduction of Cm was 5 to 10% with Tc selection. Plasmid elimination was infrequent and restricted to the Cm plasmid. A variant, doubly resistant strain gave 100% co-transduction of Tc and Cm and a high rate of joint elimination of both plasmid markers. Co-transduction of the plasmids from recombination-deficient donor strains was much reduced if the plasmids had been introduced separately into the donor strain, but occurred at the normal high rate if they had been introduced jointly. The plasmids were co-transformed at relatively low rates with closed circular deoxyribonucleic acid (DNA) from doubly resistant donors, but not with DNA from a mixed lysate of singly resistant strains. Our evidence favored a hypothesis of recombination-dependent, reversible linkage between the two plasmids as the basis for their co-transduction. Examination of plasmid DNA from the doubly resistant strains by ultracentrifugal and electron microscopic methods did not disclose any physical differences between singly and doubly resistant strains that might account for the observed co-transduction.
Evidence for the Periplasmic Location of Hydrogenase in
Desulfovibrio gigas
Authors: Bell George R. , LeGall J. , Peck Harry D.
Published: January 2020

Hydrogenase has been found to be located in the periplasmic space of
Desulfovibrio gigas
, and it is proposed that hydrogenase plays an important and specific role in interspecies hydrogen transfer.
Mutants of
Salmonella typhimurium
Defective in Transport of Branched-Chain Amino Acids
Authors: Kiritani Kazuyoshi
Published: January 2020

Five mutants, CD15, CD31, CE4, CE5, and CE14, defective in the transport of branched-chain amino acids were isolated as glycyl-
l
-isoleucine and glycyl-
l
-valine requirers from an isoleucine-valine-requiring mutant, KA931, of
Salmonella typhimurium
LT2. Although these transport mutants do not grow in minimal medium supplemented with isoleucine (10 μg/ml) and valine (20 μg/ml), where the parent strain, KA931, grows normally, they do when the supplements are increased 10-fold in concentration, and the growth rate becomes comparable to that of the parent strain. When the apparent

K
m

and

V
max

for uptake of isoleucine, valine, and leucine in the transport mutants were compared to those of KA931, the

K
m

was generally lower in the mutants, and the

V
max

for isoleucine and leucine decreased to one-fourth to one-seventh and for valine one-eighth to one-fifteenth of that in the parent. In all mutants except CE5, the transport of methionine, arginine, threonine, and glycine was normal. The transport of threonine in CE5 appeared to be slightly impaired. In addition to the original mutation in the
ilvC
locus, the transport mutant has a mutation at the
ilvT
locus, which is closely linked to
proC
and may be located on the side of
proC
proximal to
purE
. About 26-fold difference in values of the co-transduction is noted in reciprocal transductions between KA502 and CD15 strains.
Characterization of
Escherichia coli
Flagellar Mutants That are Insensitive to Catabolite Repression
Authors: Silverman Michael , Simon Melvin
Published: January 2020

In
Escherichia coli
, the synthesis of the flagellar organelle is sensitive to catabolite repression. Synthesis requires the presence of the cyclic adenosine monophosphate receptor protein (Crp) and 3′,5′-cyclic adenosine monophosphate (cAMP); i.e., mutants that lack Crp or adenylcyclase (Cya) synthesize no flagella. We isolated and characterized a series of mutants (
cfs
) that restored flagella-forming ability in a Crp strain of
E. coli
. The mutations in these strains were transferred onto episomes and they were then introduced into a variety of other strains. The presence of the mutation resulted in flagella synthesis in Cya and Crp strains as well as in the wild type grown under conditions of catabolite repression. Deletion analysis and other genetic studies indicated that: (i) the
cfs
mutations had a dominant effect when they were in the transconfiguration in merodiploids: (ii) they occurred in or very close to the
flaI
gene: and (iii) their expression required the presence of an intact
flaI
gene adjacent to the
cfs
mutation. Biochemical studies showed that the synthesis of at least two flagellar polypeptides, the hook subunit and an amber fragment of flagellin, were absent in strains that carried a
cya
mutation. Their synthesis was depressed in strains grown under conditions of catabolite repression. The presence of the
cfs
mutation restored the specific synthesis of these two polypeptides. We suggest that the formation of the
flaI
gene product is the step in flagellar synthesis that is catabolite sensitive and requires cAMP. We propose a regulatory function for the product of the
flaI
gene.
In Vivo Studies of Temperature-Sensitive
recB
and
recC
Mutants
Authors: Kushner Sidney R.
Published: January 2020

Some in vivo properties of
Escherichia coli
K-12 strains carrying
recB270
(formerly
recBts1
) and
recC271
(formerly
recCts1
) mutations have been determined. Single
recB270
and
recC271
mutants appear normal at 30 C with regard to ultraviolet and mitomycin C sensitivity, recombination proficiency, and viability. At 43 C these strains become sensitive to ultraviolet and mitomycin C, while showing only a slight decrease in recombination proficiency. The viable titers of the single mutants are somewhat reduced at 43 C. Double mutant strains carrying
polA1
and
recB270
or
recC271
are inviable at 43 C. The double mutant strain (
recB270 recC271
) is sensitive to both UV and mitomycin C at 30 C, but shows only slightly reduced recombination proficiency. At 43 C the strain resembles absolute
recB
and
recC
mutants in all respects. In addition, the double mutant strain exhibits a temperature-induced drop in viable titer. The triple mutant
polA1 recB270 recC271
is viable at 30 C. Two hypotheses are advanced to explain these results.
Replication of the Bacteriocinogenic Plasmid Clo DF13 in Thermosensitive
Escherichia coli
Mutants Defective in Initiation or Elongation of Deoxyribonucleic Acid Replication
Authors: Veltkamp E. , Nijkamp H. J. J.
Published: January 2020

The replication of the bacteriocinogenic plasmid Clo DF13 has been studied in the seven temperature-sensitive
Escherichia coli
mutants defective in deoxyribonucleic acid (DNA) replication (
dnaA-dnaG
). Experiments with
dna
initiation mutants revealed that the replication of the Clo DF13 plasmid depends to a great extent on the host-determined
dnaC
(
dnaD
) gene product, but depends slightly on the
dnaA
gene product. The synthesis of Clo DF13 plasmid DNA also requires the
dnaF
and
dnaG
gene products, which are involved in the elongation of chromosomal DNA replication. In contrast, the Clo DF13 plasmid is able to replicate in the
dnaB
and
dnaE
elongation mutants at the restrictive temperature. When de novo protein synthesis is inhibited by chloramphenicol in wild-type cells, the Clo DF13 plasmid continues to replicate for at least 12 h, long after chromosomal DNA synthesis has ceased, resulting in an accumulation of Clo DF13 DNA molecules of about 500 copies per cell. After 3 h of chloramphenicol treatment, the Clo DF13 plasmid replicates at a rate approximately five times the rate in the absence of chloramphenicol. Inhibition of protein synthesis by chloramphenicol does not influence the level of Clo DF13 DNA synthesis at the restrictive temperature in the
dna
mutants, except for the
dnaA
mutant. Chloramphenicol abolishes the inhibition of Clo DF13 DNA synthesis in the
dnaA
mutant at the nonpermissive temperature. Under these conditions, Clo DF13 DNA synthesis was slightly stimulated in the first 30 min after the temperature shift, and continued for more than 3 h at an almost uninhibited level.
R-Factor Mutant Capable of Specifying Hypersynthesis of Penicillinase
Authors: Odakura Yoshihiro , Hashimoto Hajime , Mitsuhashi Susumu
Published: January 2020

The physical characteristics of a mutant, R
M201-2
, capable of conferring high and stable ampicillion resistance was analyzed. The R
M201-2
and its parent R-factor deoxyribonucleic acid (DNA) could be isolated as an extrachromosomal and covalently closed circular form. Their buoyant densities were both 1.712 g/cm
3
, and their molecular weights were about 82 × 10
6
and 64 × 10
6
, respectively, when measured by CsCl and sucrose density gradient analyses. The contour lengths by electron microscopy were 35.9 ± 0.6 and 31.0 ± 0.6 μm, respectively. By using the extracted R-factor DNA, the mutant and parent characters were transformable to another
Escherichia coli
strain. The mutant R factor showed an increased amount of DNA even after conjugal transfer to
Proteus
. An increase in the size of R-factor DNA was thus considered to be the cause of the high level of ampicillin resistance.
Genetic Mapping of Linked Antibiotic Resistance Loci in
Neisseria gonorrhoeae
Authors: Sarubbi Felix A. , Blackman Eleanor , Sparling P. Frederick
Published: January 2020

Loci for resistance to several antibiotics in laboratory-derived strains of
Neisseria gonorrhoeae
were mapped by genetic transformation. Genes for high-level resistance to streptomycin (
str
) and spectinomycin (
spc
) and for low-level resistance to tetracycline (
tet
) and chloramphenicol (
chl
) were linked. Also, a locus for high-level resistance to rifampin (
rif
) was linked to
str
and
tet
. The apparent order was
rif... str... tet... chl... spc
. Loci for resistance to other antibiotics (penicillin, erythromycin) were transferred independently of each other and were not linked to the cluster around
str
. Similar linkage relationships were found with
str, tet, chl
, and
spc
loci obtained from naturally occurring (clinical) isolates of
N. gonorrhoeae
.
Ribosomal Resistance to Streptomycin and Spectinomycin in
Neisseria gonorrhoeae
Authors: Maness Michael J. , Foster Gayle C. , Sparling P. Frederick
Published: January 2020

A cell-free protein synthesizing system was used to study the mechanism of resistance to streptomycin (Str) and spectinomycin (Spc) in laboratory mutants and clinical isolates of
Neisseria gonorrhoeae
. The 70
S
ribosomes from sensitive strains were sensitive to the effects of Str and Spc on synthesis directed by several synthetic polynucleotide messengers, whereas 70
S
ribosomes from resistant strains were resistant to these same effects. In each case, the alteration was localized to the 30
S
ribosomal subunit by studying antibiotic sensitivities of hybrid 70
S
ribosomes formed by combining subunits from sensitive and resistant strains. No evidence was found for streptomycin- or spectinomycin-inactivating enzymes.
R6K Plasmid Replication: Influence of Chromosomal Genotype in Minicell-Producing Strains of
Escherichia coli
K-12
Authors: Macrina Francis L. , Weatherly George G. , Curtiss Roy
Published: January 2020

Alkaline sucrose velocity sedimentation and cesium chloride-ethidium bromide equilibrium centrifugation have been used to determine the number of copies per chromosomal equivalent of the relaxedly replicating R6K plasmid (a conjugative plasmid conferring ampicillin and streptomycin resistance) in two minicell-producing strains of
Escherichia coli
K-12. In one strain, the average number of covalently closed circular R6K molecules per chromosomal equivalent is 13 in log-phase and 35 in stationary-phase cells. In the other strain, there is an average of six covalently closed circular R6K molecules per chromosomal equivalent in both log- and stationary-phase cells. Selection from this strain of spontaneously occurring mutants resistant to high concentrations of ampicillin has been accomplished and such mutants show a two- to threefold increase in the number of R6K copies per chromosomal equivalent. Relative to the parental strain, mutants display the following properties: (i) elevated streptomycin resistance, (ii) a 10-fold increase in R6K conjugal transfer, (iii) a 10-fold increase in the amount of R6K plasmid deoxyribonucleic acid segregated into minicells, and (iv) a two- to threefold increase in R6K-specified β-lactamase. The mutation(s) responsible for the increase in the number of R6K molecules per chromosomal equivalent is located on the bacterial chromosome. No R6K-linked mutations conferring the above phenotypes have been obtained. The mutations are presumed to be in chromosomal genes which play a role in the regulation of R6K replication in this strain.
R Factor Proteins Synthesized in
Escherichia coli
Minicells: Membrane-Associated R Factor Proteins
Authors: Levy Stuart B. , McMurry Laura , Palmer Edward
Published: January 2020

R factor proteins are synthesized in R factor-containing
Escherichia coli
minicells. Half of this protein remained associated with the minicell membrane upon lysis of the minicells. Over 90% of the membrane-associated protein was extracted by sodium lauryl sarcosinate, suggesting a location of these proteins in the inner membrane. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of these membrane preparations demonstrated the presence of multiple peptides, including a prominent band with a molecular weight of 28,000 to 30,000. A polypeptide of similar size was seen in membrane preparations from minicells harboring R factors from five different compatibility types. This major R factor membrane peptide was seen with R factors repressed or derepressed for pilus synthesis, with and without antibiotic resistances. It was associated with R factor deoxyribonucleic acid in membrane-deoxyribonucleic acid complexes. Its possible role in R factor replication and/or transfer is being investigated.
Inhibition of Induction of Competence in
Pneumococcus
by Isologous Teichoic Acid
Authors: Rejholcová M. , Tichá M. , Kohoutová M. , Kocourek J.
Published: January 2020

Pneumococcal teichoic acid inhibits induction of competence in incompetent cells of
Pneumococcus
. The inhibitory effect is very similar to that observed in the presence of
d
-glucosamine and
d
-galactosamine.
Oxygen-dependent inactivation of glutamine phosphoribosylpyrophosphate amidotransferase in vitro inactivation
Authors: Turnbough C L , Switzer R L
Published: January 2020

The oxygen-dependent inactivation of glutamine phosphoribosylpyrophosphate amidotransferase (ATase) is demonstrated in cell extracts of Bacillus subtilis. The rate of inactivation of ATase in vitro is apparently first order with respect to oxygen concentration and ATase activity. ATase inactivation in vitro (or in vivo) cannot be reactivated by a variety of reductants. ATase is significantly stabilized to oxygen-dependent inactivation in vitro in the presence of tetrasodium phosphoribosylpyrophosphate and glutamine together. The effects of the end product inhibitors, adenosine 5-monophosphate (AMP) and guanosine 5-monophosphate (GMP), on the stability of ATase are antagonistic. AMP stabilizes ATase, whereas GMP destabilizes the enzyme. The stability of ATase can be manipulated over wide ranges by variations in the AMP/GM ratio. The effects of AMP and GMP on the inactivation of ATase in vitro are very specific. ATase is partially inhibited by 1,10-phenanthroline, suggesting that the enzyme contains iron (or some other chelatable metal ion). The inactivation of ATase in vitro is proposed to present a model for the reconstruction of the inactivation of ATase in stationary-phase cells of B. subtilis.