bluuebunny/crossref_metadata_2025 huggingface dataset:
Properties of a Deoxyribonucleic Acid Ligase Mutant of
Escherichia coli:
X-Ray Sensitivity
Authors: Dean Cynthia , Pauling Crellin
Published: January 2020

A deoxyribonucleic acid ligase-deficient mutant is X-ray sensitive relative to the parent strain, suggesting that deoxyribonucleic acid ligase functions in repair of X-ray-induced, single-strand scissions.
Continued Expression of the Ribonucleic Acid Control Gene During Inhibition of
Escherichia coli
Ribonucleic Acid and Protein Synthesis
Authors: Khan S. R. , Yamazaki Hiroshi
Published: January 2020

The effect of the ribonucleic acid (RNA) control (RC) gene on the biosynthesis of viral RNA has been examined in an RC
str
and an RC
rel
host infected with R17 RNA bacteriophage under conditions in which host RNA and protein synthesis were inhibited by the addition of rifampicin. Methionine and isoleucine starvation depressed viral RNA biosynthesis in an RC
str
host but not in an RC
rel
host. However, histidine starvation had little effect on viral RNA and protein synthesis in both RC
str
and RC
rel
cells, although it had a marked effect on host protein and RNA synthesis in an RC
str
host. Chloramphenicol relieved the effect of amino acid starvation on viral RNA synthesis in an RC
str
host. It is concluded that stringent control of viral RNA biosynthesis does not require the continued biosynthesis of the RC gene product (RNA or protein) and that a preformed RC gene product can regulate the biosynthesis of the exogenous RNA. It is suggested that the amino acid dependence of viral RNA biosynthesis is due to its obligatory coupling with the translation of the viral coat protein which lacks histidine. It may be inferred that the amino acid requirement of bacterial RNA is due to its coupling with the translation of a host-specific protein (other than the RC gene product) which requires a full complement of amino acids. Since chloramphenicol is known to permit ribosome movement in the absence of protein synthesis, it is suggested that ribosome movement along the nascent RNA chain is a sufficient condition for the continuation of RNA synthesis.
Lysostaphin-Induced, Osmotically Fragile
Staphylococcus aureus
Cells
Authors: Huber T. W. , Schuhardt V. T.
Published: January 2020

Staphylococcus aureus
FDA 209P cells when suspended in 24% (w/v) NaCl were rendered osmotically fragile by exposure to lysostaphin for time intervals ranging from 2 to 60 min. Such cells were analyzed chemically and serologically for evidence of residual cell wall material, were plated in hypertonic sucrose medium to determine revertibility to normal, and were subjected to manometric studies to determine metabolic capabilities. Most of the cells (95%) which were exposed to lysostaphin (0.5 or 1.0 unit/ml) for 2 min, although osmotically fragile, retained their cell wall hexosamine and were capable of reverting to osmotically normal cells when plated in hypertonic medium. Cells exposed to lysostaphin for 5 and 10 min also retained much of their cell wall hexosamine, but lost their ability to revert to normal staphylococci. Cells exposed to lysostaphin for 2 to 10 min continued to react with staphylococcus anti-k antiserum. Complete removal of cell wall hexosamine was attained only after exposure to lysostaphin for 20 min or more; these cells failed to react with k antiserum. Lysostaphin-induced L-type colonies were extremely rare in our experiments, even if incubation times and media were optimal for their detection. Lysostaphin-induced staphylococcal protoplasts were as active metabolically in manometric studies as were untreated staphylococci.
Operon Coordination in Different Bacterial Hosts
Authors: Wu Po Chi , Johnson Peter F. , Newton Austin
Published: January 2020

Coordination of gene expression in the
lac
operon was compared in
Escherichia coli
and
Salmonella typhimurium
as an approach to detecting possible differences in protein synthesis or membrane structure between organisms. Either a wild-type F′
lac pro
AB
episome or the same episome with a polar mutation in one of the
lac
genes was introduced into
pro
−
derivatives of the two strains of bacteria. Activity assays showed that the β-galactosidase levels were only slightly lower in the
S. typhimurium
cells than in
E. coli
cells, whereas the transacetylase levels were significantly higher in
S. typhimurium
for all of the
lac
markers tested. Galactoside transport activities were always comparable in the two strains of bacteria; this latter result indicates that the cell envelopes of
E. coli
and
S. typhimurium
do not differ sufficiently to affect the membrane-associated
lac
transport system. It was found, however, that the specific transport activity is very sensitive to culture age in both bacteria, and decreases rapidly in cultures past the mid-exponential phase of growth.
Genetic Analysis of a Large-Cell, Radiation-Resistant Strain of
Escherichia coli
Authors: Kvetkas Marilyn J. , Krisch Robert E. , Zelle Max R.
Published: January 2020

A genetic analysis of
Escherichia coli
P6, a large-cell, radiation-resistant strain of
E. coli
, established that it originated as the result of a mutational event. The gene responsible for the complex P6 phenotype was located at 61 ± 0.5 min on the
E. coli
linkage map. The close resemblance of conjugal and transductional recombinants to one or the other parent without indication of an intermediate class suggests that only a single gene may be involved.
Relationship Between Radiation Response and the Deoxyribonucleic Acid Replication Cycle in Bacteria: Dependence on the Excision-Repair System
Authors: Billen Daniel , Bruns Laura
Published: January 2020

Prestarvation of
Escherichia coli
for required amino acids results in a marked enhancement in both ultraviolet light (UV) or X-ray resistance for selective strains. Preventing protein synthesis by starvation for required amino acids results in completion of the cycle of chromosomal replication then underway. We have investigated the relationship between starvation-induced resistance enhancement (SIRE) and the excision-repair (Hcr) system in several
E. coli
strains including
E. coli
B/r
hcr
+
and its isogenic mutant
E. coli
B/r
hcr
−
. The following observations were made. (i) The Hcr system is the major component of SIRE in UV-irradiated strain B/r. By using the Hcr
+
strain, SIRE increases the 10% survival dose from ∼400 ergs to ∼1,200 ergs/mm
2
. With the Hcr cells, the increase is from ∼45 ergs to 60 ergs/mm
2
. (ii) Although prestarvation leads to a moderate enhancement of resistance to X irradiation, this effect is not dependent on the Hcr system. (iii) The double mutant,
E. coli
B
s–1
(
hcr
−
exr
−
) is completely unable to express SIRE whether studied with UV or X irradiation. It is concluded that the Hcr system is the major system responsible for SIRE in UV-treated cells, whereas Exr (resistance to X rays) may be involved to a minor extent. The Exr character appears to be required for SIRE expression in X-ray exposed cells.
Roles of Acetate and Pyruvate in the Metabolism ofStreptococcus diacetilactis
Authors: Collins E. B. , Bruhn J. C.
Published: January 2020

Streptococcus diacetilactisrequired acetate, contained acetate kinase and phosphotransacetylase, and incorporated both radioactive exogenous acetate and acetate from citrate into cell lipids.dl-α-Lipoic acid replaced acetate and was required for the oxidation of pyruvate. Stimulation ofS. diacetilactisby citrate was found to depend on pyruvate oxidation. Resting cells of the organism produced acetate from 73% of the pyruvate they utilized. However, molar growth yields from glucose were not greater under aerobic compared to anaerobic conditions or when lipoic acid or citrate plus lipoic acid was used in the medium in place of acetate. Data indicate that the growth ofS. diacetilactisis limited by the rate of acetyl-coenzyme A synthesis, that the rate of synthesis from pyruvate is higher than the rate from acetate, and that lack of acetyl-coenzyme A not required for growth limits the production of diacetyl and precludes the formation of adenosine triphosphate from acetyl-coenzyme A.
Genetic Mapping in
Escherichia coli
K-12 by Radiation-Induced Crossing-Over
Authors: Wann M. , Mahajan S. K. , Wood T. H.
Published: January 2020

Conventional methods for chromosomal mapping in
Escherichia coli
are (i) interruption of matings to obtain minimum marker entry times, (ii) linkage analysis of recombinants, and (iii) cotransduction. Method (i) has a resolution of about 0.5 min (5 × 10
4
nucleotides) and is not useful for distances less than about 1 min; methods (ii) and (iii) are capable of better resolution but are generally not very reproducible and no general theory is available for translating crossing-over and cotransduction frequencies into physical chromosomal distances. We found that when merozygotes are irradiated (X rays or ultraviolet light) soon after marker transfer, high linkage values (0.8 to 1.0) between nearby marker pairs decrease with radiation dose to 0.5. Our results are quantitatively consistent with the idea that radiations induce crossing-over lesions proportional to dose, and the number of such lesions between two markers is proportional to the physical separation of the markers in the range that can also be measured by interruption of mating (0.5 to 4.0 min). Additivity relations among markers are also satisfied. We used this technique to measure the distances (0.1 to 1.0 min) between several pairs of closely linked markers.
Heterogeneity Among Strains ofMycoplasma granularumand Identification ofMycoplasma hyosynoviae, sp. n
Authors: Ross R. F. , Karmon Judith A.
Published: January 2020

Twelve filtrable, pleomorphic organisms isolated from swine joints and respiratory tracts had typical colonial and microscopic characteristics of mycoplasmas. They resisted penicillin and did not revert to cell wall-producing bacterial forms in media devoid of bacterial inhibitors. The morphological and growth characteristics of these mycoplasmas were similar to those described previously forMycoplasma granularum. However, a new name,M. hyosynoviae, is proposed for them since they differed biologically, serologically, and electrophoretically from the prototype strain ofM. granularum. M. hyosynoviaerequired sterols, was stimulated by gastric mucin, and metabolized arginine; however, it did not metabolize urea, ferment glucose, or reduce tetrazolium. The organism produced “film and spots” on horse serum-supplemented medium and produced alpha hemolysis of guinea pig and sheep erythrocytes; however, it did not digest serum, produce phosphatase, or hemadsorb guinea pig or swine erythrocytes.M. hyosynoviaewas distinguished from three other swine mycoplasmas,M. granularum, M. hyorhinis, andM. laidlawii, by means of acrylamide gel electrophoresis, growth inhibition, metabolic inhibition, and immunodiffusion techniques. It was also serologically and electrophoretically distinct from 13 additional non-swine mycoplasmas which require sterols and metabolize arginine.
Resistance of Minicells to Penicillin Lysis: a Method of Obtaining Large Quantities of Purified Minicells
Authors: Levy Stuart B.
Published: January 2020

Penicillin has been used to purify large quantities of minicells.
Formation of Aromatic Amino Acid Pools in
Escherichia coli
K-12
Authors: Brown K. D.
Published: January 2020

Phenylalanine, tyrosine, and tryptophan were taken up into cells of
Escherichia coli
K-12 by a general aromatic transport system. Apparent Michaelis constants for the three amino acids were 4.7 × 10
−7
, 5.7 × 10
−7
, and 4.0 × 10
−7
m
, respectively. High concentrations (> 0.1 m
m
) of histidine, leucine, methionine, alanine, cysteine, and aspartic acid also had an affinity for this system. Mutants lacking the general aromatic transport system were resistant to
p
-fluorophenylalanine, β-2-thienylalanine, and 5-methyltryptophan. They mapped at a locus,
aroP
, between
leu
and
pan
on the chromosome, being 30% cotransducible with
leu
and 43% cotransducible with
pan
. Phenylalanine, tyrosine, and tryptophan were also transported by three specific transport systems. The apparent Michaelis constants of these systems were 2.0 × 10
−6
, 2.2 × 10
−6
, and 3.0 × 10
−6
m
, respectively. An external energy source, such as glucose, was not required for activity of either general or specific aromatic transport systems. Azide and 2,4-dinitrophenol, however, inhibited all aromatic transport, indicating that energy production is necessary. Between 80 and 90% of the trichloroacetic acid-soluble pool formed from a particular exogenous aromatic amino acid was generated by the general aromatic transport system. This contribution was abolished when uptake was inhibited by competition by the other aromatic amino acids or by mutation in
aroP
. Incorporation of the former amino acid into protein was not affected by the reduction in its pool size, indicating that the general aromatic transport system is not essential for the supply of external aromatic amino acids to protein synthesis.
Formation of Bacteriolytic Enzymes in Batch and Continuous Culture of
Staphylococcus aureus
Authors: Arvidson Staffan , Holme Tord , Wadström Torkel
Published: January 2020

The formation of bacteriolytic enzymes of
Staphylococcus aureus
, with special reference to strain M18, was investigated under a variety of conditions. The bacteriolytic activity was tested by using whole cells of
Micrococcus lysodeikticus
as a substrate. Complex media were required for production, and a Casein Hydrolysate-Yeast Extract medium (CCY
I
) was superior to Brain Heart Infusion and Trypticase Soy Broth. The optimal
p
H level for production was 7.0. Effective oxygenation and exchange of the β-glycerophosphate of the CCY
I
medium for glucose increased the rates of growth and autolysis and the rate of appearance of extracellular bacteriolytic enzymes. However, the extracellular lytic activity decreased more rapidly at the end of the growth period than under the standard culture conditions. The appearance of inhibitor(s), probably derived from autolysis, might be responsible for this rapid decrease. The highest yields were obtained in a continuous process in which the activity was almost twice that of batch cultures grown under the same conditions. The bacteriolytic activity produced in continuous culture had a considerably increased stability in the purification process. The advantage of producing unstable bacterial proteins in continuous culture under controlled growth conditions is discussed.
Biosynthesis of α-Ketoglutarate by the Reductive Carboxylation of Succinate inBacteroides ruminicola
Authors: Allison Milton J. , Robinson I. M.
Published: January 2020

Experiments with growing cells and with cell-free extracts ofBacteroides ruminicolaindicate that this anaerobic bacterium can synthesize α-ketoglutarate by a reductive carboxylation of succinate. When the organism was grown in medium containing succinate-1,4-14C, most of the radioactivity in cells was in the protein fraction and most of the14C in protein was in the glutamic acid family of amino acids (glutamate, proline, and arginine). When unlabeled succinate was added to culture medium containing glucose-U-14C, incorporation of radioactivity into the glutamic acid family of amino acids was greatly reduced. This supports the concept that succinate is an intermediate in synthesis of α-ketoglutarate. Cell-free extracts of the organism incubated with succinate-1,4-14Cincorporated14C into amino acids and most of this was found in glutamate. The cofactors which stimulate glutamate synthesis from succinate by extracts from these cells appear to be similar to the factors that have been demonstrated with extracts from photosynthetic bacteria. The position of label in glutamate synthesized from succinate-1,4-14C, the probable absence of isocitric dehydrogenase, and studies with labeled citrate and with inhibitors of citric acid cycle enzymes support the concept of a reductive carboxylation of succinate as the only, or at least a major, mechanism for synthesis of α-ketoglutarate in this organism. This appears to be the first evidence for a net synthesis of α-ketoglutarate by this reaction in a nonphotosynthetic heterotrophic organism.
Relationship Between Solute Permeability and Osmotic Remediability in a Galactose-Negative Strain of
Saccharomyces cerevisiae
Authors: Bassel John , Douglas Howard C.
Published: January 2020

An osmotic remedial allele, gal 7-1, in the galactose pathway of
Saccharomyces cerevisiae
responds to either penetrating (ethylene glycol and diethylene glycol) or nonpenetrating (KCl, NaCl, and sorbitol) solutes in the growth medium. Extracts from cells grown under restrictive conditions gave no increase in enzyme activity (gal-1-phosphate, uridylyl transferase) when exposed to the penetrating solutes; thus protein synthesis or possibly polymer assembly is proposed as the critical step remedied by the addition of the solutes.
Protein Composition of the Cell Wall and Cytoplasmic Membrane of
Escherichia coli
Authors: Schnaitman Carl A.
Published: January 2020

Envelope preparations obtained by passing
Escherichia coli
cells through a French pressure cell were separated by sucrose density gradient centrifugation into two distinct particulate fractions. The fraction with the higher density was enriched in fragments derived from the cell wall, as indicated by the high content of lipopolysaccharide, the low content of cytochromes, and the similar morphology of the fragments and intact cell walls. The less-dense fraction was enriched in vesicles derived from the cytoplasmic membrane, as indicated by the enrichment of cytochromes, the enzymes lactic and succinic dehydrogenase and nitrate reductase, and the morphological similarity of the vesicles to intact cytoplasmic membrane. Both fractions were rich in phospholipid. The protein composition was compared by mixing the cytoplasmic membrane-enriched fraction from a
3
H-labeled culture with the cell wall-enriched fraction from a
14
C-labeled culture and examining the resulting mixture by gel electrophoresis. Thirty-four bands of radioactive protein were resolved; of these, 27 were increased two- to fourfold in the cytoplasmic membrane-enriched fraction, whereas 6 were similarly increased in the cell wall-enriched fraction. One of the proteins which is clearly localized in the cell wall is the protein with a molecular weight of 44,000, which is the major component of the envelope. This protein accounted for 70% of the total protein of the cell wall, and its occurrence in the envelope from spheroplasts suggests that it is a structural protein of the outer membranous component of the cell wall.
Chemical Composition of Chlamydospores of
Candida albicans
Authors: Jansons Vilma K. , Nickerson Walter J.
Published: January 2020

A variety of analytical techniques was employed to study the composition of the chlamydospore of
Candida albicans
. The outer, thin, electron-transparent layer was found to be composed of glucan, together with a small amount of chitin. The inner, thick, electron-dense layer is proteinaceous. The central structure is composed largely of ribonucleic acid and lipid globules. In addition to being acid-fast, the chlamydospore was found to contain glycolipids and to lose the property of acid-fastness on extraction with ethanol-ether.
Isolation and Characterization of a Galactosamine Wall from Spores and Spherules of
Physarum polycephalum
Authors: McCormick J. Justin , Blomquist Judith C. , Rusch Harold P.
Published: January 2020

The myxomycete,
Physarum polycephalum
, can be induced under laboratory conditions to form two different hard-walled forms, spores and spherules. Characterization of both types of walls revealed only a single sugar, galactosamine. It was identified after acid hydrolysis of the isolated walls by chromatography in three solvent systems, by its positive reaction with ammoniacal silver nitrate, ninhydrin, Galactostat, and the Elson-Morgan test, and by ninhydrin degradation to lyxose. Galactosamine was present as a polymer with solubility characteristics the same as the β1-4–linked glucosamine polymer (chitosan). The walls were also found to contain about 2% protein. Spherule walls revealed a single glycoprotein on gel electrophoresis. Spore walls contained a similar protein component. The phosphate content of isolated spherule walls was 9.8%, and that of spore walls was 1.4%. Spore walls also contained about 15% melanin which was shown to be similar to fungal melanin. A novel method was used to measure the rate of mature spherule formation based on the loss of extractability of
P. polycephalum
natural pigment. The presence of a rare galactosamine polymer in
P. polycephalum
spore and spherule walls as the only carbohydrate suggests that the myxomycetes are not closely related to the fungi or the protozoa.
Mechanism of Colicin Action: Early Events
Authors: Wendt Louis
Published: January 2020

The kinetics and the temperature dependence of potassium loss from
Escherichia coli
cells treated with colicin K have been examined. At 37 C, after a single lethal hit, essentially all of the intracellular potassium is lost within the first few minutes of treatment. The initial rate of loss is linearly related to colicin concentration up to a multiplicity of 30. As the temperature is decreased over the range from 37 to 1 C, an increasing delay is seen in the initiation of potassium loss after colicin adsorption. This delay can be overcome by increasing colicin multiplicity and probably reflects an alteration of the cell membrane at these temperatures. A comparison of this effect with an apparently related effect of temperature on the action of irehdiamine A indicates that the delay may represent the inhibition of a transmission process occurring in the membrane.
Temperature-Sensitive Osmotically Fragile Mutants of
Staphylococcus aureus
Authors: Good C. M. , Pattee P. A.
Published: January 2020

Temperature-sensitive fragile mutants of
Staphylococcus aureus
which grow at the restrictive temperature only in the presence of osmotic stabilizers and appear to have conditionally defective cell wall integrity were isolated and partially characterized.
Control of Expression of the
l
-Arabinose Operon in Temperature-Sensitive Mutants of Gene
araC
in
Escherichia coli
B/r
Authors: Irr Joseph , Englesberg Ellis
Published: January 2020

Expression of the
l
-arabinose operon in
Escherichia coli
B/r is dependent on the temperature of growth of the
araC
mutants reported in this paper. Analysis of these temperature-sensitive regulatory mutants indicates that both repressor and activator activities are thermolabile. The simplest model to explain the manner in which the operon is controlled is one suggesting that the regulatory gene,
araC
, codes for a protein which upon synthesis acts as a repressor molecule and prevents operon function. When inducer is added, the repressor undergoes a conformational shift and becomes an activator which switches on enzyme synthesis, provided the repressor concentration is reduced to a sufficiently low level in the cell. These data lend strong support to the model that both activities are the result of the same gene product.
Purified Protoplasmic Peptides of Mycobacteria: Chemical Composition of a Tuberculin-Active Glycopeptide
Authors: Stottmeier K. D. , Beam R. E. , David H. L. , Shapira Raymond , Farshy D. C.
Published: January 2020

A tuberculin-active glycopeptide containing eight different amino acids and glucose was isolated from the protoplasm of
Mycobacterium tuberculosis
. A molecular weight of 4,000 to 5,000 was established by Sephadex gel filtration; other analyses showed a peptide to carbohydrate ratio of 9:1. These observations suggest a tentative composition of 3 to 4 residues of glucose, 12 residues each of aspartic and glutamic acids, 3 residues each of lysine, glycine, and serine, and 1 residue each of arginine, threonine, and alanine.
Physiological Studies of Encystment in
Azotobacter vinelandii
Authors: Sadoff H. L. , Berke E. , Loperfido B.
Published: January 2020

Azotobacter vinelandii
, in late exponential growth phase, encysts when the glucose in the medium is replaced with β-hydroxybutyrate. A final cell division then occurs without apparent deoxyribonucleic acid (DNA) synthesis, resulting in a reduction from two to one nucleoids per cell and a final DNA content of 3.2 × 10
−14
g per cell. This is also the DNA content per cyst. A β-hydroxybutyrate dehydrogenase is derepressed by the addition of the inducer and is identical to the enzyme in acetate-grown cells in its
p
H optimum, Michaelis constant for substrate, temperature-activity response, and mobility during electrophoresis in acrylamide gel.
Purification and Properties of Glycogen Isolated from a Blue-Green Alga,
Nostoc muscorum
Authors: Chao Lee , Bowen C. C.
Published: January 2020

Alpha granules were isolated from a blue-green alga,
Nostoc muscorum
, in large quantities and high purity by sucrose density gradient centrifugation. Sodium deoxycholate was used to eliminate membrane contamination. Isolated α granules from this species have average dimension of 31 nm in width and 65 nm in length. Each α granule consists of two equal parts. Attempts to dissociate the intact granule under mild conditions into relatively large subunits did not succeed. Analytical centrifugation of the α granules yields a sedimentation coefficient of 265
S
(
S
20, w
). Chemical analysis reveals that α granules contain highly branched polyglucosyl units with short external chain lengths.
Attachment of Flagellar Basal Bodies to the Cell Envelope: Specific Attachment to the Outer, Lipopolysaccharide Membrane and the Cytoplasmic Membrane
Authors: DePamphilis M. L. , Adler Julius
Published: January 2020

A procedure is described for the purification of the
Escherichia coli
outer membrane (lipopolysaccharide or L membrane) with flagella still attached. The resulting lipopolysaccharide membrane was in the form of vesicles that had a trilaminar structure in thin section and contained about 55% lipopolysaccharide and 45% protein. T2 or T4 phage preadsorbed to
E. coli
were found attached to the purified lipopolysaccharide membrane. Flagella were bound to the purified lipopolysaccharide membrane specifically at the basal body ring closest to the hook (the L ring). The cytoplasmic membrane in preparations from osmotically lysed
E. coli
spheroplasts or
Bacillus subtilis
protoplasts was specifically attached to flagella at the basal body ring farthest from the hook (the M ring). In the
E. coli
preparation, lipopolysaccharide membrane was also present and was attached to the L ring. From these data and a knowledge of the structure and dimensions of the
E. coli
flagellar basal body and cell envelope, a model for flagellar attachment is deduced.
Synthesis of Protein and Nucleic Acid by Disrupted Spheroplasts of
Pseudomonas schuylkilliensis
Authors: Mizuno Shigeki , Matsuzawa Hiroshi , Nagata Yoshiho , Shibuya Isao , Takahashi Hajime , Maruo Bunji
Published: January 2020

Osmotically shocked spheroplasts obtained from
Pseudomonas schuylkilliensis
strain
P
contained about 54, 32, 28, and 82% of the total cellular protein, ribonucleic acid (RNA), deoxyribonucleic acid (DNA), and phospholipid, respectively. This preparation was capable of incorporating
32
P-orthophosphate into RNA and DNA,
3
H-adenosine or
3
H-uridine into RNA, and
3
H-leucine or
14
C-phenylalanine into protein. These activities were not found in the cytoplasmic fraction which contained most of the glucose-6-phosphate dehydrogenase activity. The synthesis of RNA by intact and disrupted spheroplast preparations was sensitive to actinomycin D, chromomycin A
3
, streptovaricin, rifampin, Lubrol W, Triton X-100, and sodium deoxycholate, whereas RNA synthesis by intact cells was insensitive to these agents. Ethylenediaminetetraacetic acid, porcine pancreatic lipase, the protoplast-bursting factor, high concentrations of salts, and washing the preparation inhibited the synthesis of RNA by disrupted spheroplasts but had little or no effect on intact spheroplasts. Most of the newly synthesized RNA made by disrupted spheroplasts had the characteristics of messenger RNA. The DNA present in this preparation functioned as a template for RNA synthesis; continued protein synthesis was dependent on concomitant RNA synthesis. An unusual feature of the preparation was the finding that the synthesis of macromolecules was completely dependent on oxidative phosphorylation.
Endomyces tetrasperma
, sp. n
Authors: Macy J. M. , Miller M. W.
Published: January 2020

A new fungal species has been described and placed in the genus
Endomyces. Endomyces tetrasperma
forms a true septate, multinucleate mycelium which breaks up into arthrospores. Ascus formation occurs after isogamous copulation between sexual protuberances which develop at the ends of arthrospores or between two cells, adjacent mycelial cells, or arthrospores. The asci which dehisce at maturity release two to four smooth, ovoid, thick-walled spores, each containing two oil droplets. The proposed life cycle is based on morphological and cytological observations.
Genetics of Sulfate Transport by
Salmonella typhimurium
Authors: Ohta Noriko , Galsworthy Peter R. , Pardee Arthur B.
Published: January 2020

Sixty-four mutants were isolated from the LT-2 wild-type strain of
Salmonella typhimurium
by selecting for chromate resistance. The majority of lesions were shown to lie in the
cysA
gene. (i) The mutants cannot take up sulfate, a finding which verifies the role of
cysA
in sulfate transport. In addition, 52 sulfate-transport mutants isolated without chromate selection were defective in the
cysA
gene. (ii) Most had less than 25% of the binding activity of the wild-type strain. (iii) Most had normal sulfite reductase (H
2
S-nicotinamide adenine dinucleotide phosphate oxidoreductase, EC 1.8.1.2) activity. (iv) Their sulfate-binding protein (binder) appears electrophoretically and immunologically normal. (v) Amber
cysA
mutants also make apparently normal binder in small amounts. (vi) All classical
cysA
mutants tested, including two with long deletions, had normal binding activity. From these observations, it is suggested that the
cysA
gene does not code for the binder. But many mutations in this gene reduce the binding activity in some unknown way. Other mutants, identified as
cysB
mutants, had neither binding nor uptake activities and their sulfite reductase activities were similarly reduced, thus confirming the regulatory role of the
cysB
gene. When binder was detectable, it had wild-type properties. No mutations in the binder gene were found among more than 100 mutants examined. Thus, sulfate binding has not been established as a part of sulfate transport. However, the production of binder is intimately connected with
cysA
, the established sulfate transport gene, and is regulated by the same mechanism that regulates both transport and the rest of the cysteine biosynthetic pathway.
Metabolism of Exogenous Purine Bases and Nucleosides by
Salmonella typhimurium
Authors: Hoffmeyer J. , Neuhard J.
Published: January 2020

Purine-requiring mutants of
Salmonella typhimurium
LT2 containing additional mutations in either adenosine deaminase or purine nucleoside phosphorylase have been constructed. From studies of the ability of these mutants to utilize different purine compounds as the sole source of purines, the following conclusions may be drawn. (i)
S. typhimurium
does not contain physiologically significant amounts of adenine deaminase and adenosine kinase activities. (ii) The presence of inosine and guanosine kinase activities in vivo was established, although the former activity appears to be of minor significance for inosine metabolism. (iii) The utilization of exogenous purine deoxyribonucleosides is entirely dependent on a functional purine nucleoside phosphorylase. (iv) The pathway by which exogenous adenine is converted to guanine nucleotides in the presence of histidine requires a functional purine nucleoside phosphorylase. Evidence is presented that this pathway involves the conversion of adenine to adenosine, followed by deamination to inosine and subsequent phosphorolysis to hypoxanthine. Hypoxanthine is then converted to inosine monophosphate by inosine monophosphate pyrophosphorylase. The rate-limiting step in this pathway is the synthesis of adenosine from adenine due to lack of endogenous ribose-l-phosphate.
Chromosomal Integration of F′ Factors in Recombination-Deficient Hfr Strains of
Escherichia coli
Authors: DeVries Joanne K. , Maas W. K.
Published: January 2020

In matings between F′ donors and recombination-deficient Hfr recipients, we isolated progeny which transferred both episomal markers and Hfr markers early and with high frequency. A number of these progeny had two integrated sex factors. Investigation of these double Hfr strains showed that the F′ nearly always integrated in a homologous region of the chromosome. In any particular mating system integration was specific as to location and direction of chromosome transfer.
Survival and Macromolecular Synthesis During Incubation of
Escherichia coli
in Limiting Thymine
Authors: Deutch Charles E. , Pauling Crellin
Published: January 2020

Survival and the synthesis of deoxyribonucleic acid (DNA), ribonucleic acid (RNA), and protein were measured during incubation of a thymine auxotroph of
Escherichia coli
in a series of media containing thymine concentrations below the optimal level of 2 μg/ml. The rate of increase in viable count gradually diminishes to no net growth with 0.2 μg/ml. With lower concentrations of thymine, the rate of cell death gradually increases, resulting in a typical thymineless death curve with 0.02 μg/ml. Both the rate of cell growth and the rate of cell inactivation vary linearly with the thymine concentration. Thirty minutes of incubation in media containing limiting concentrations of thymine before a shift to complete thymine starvation results in a progressive decrease in the length of the lag period preceding thymineless death. These data suggest that only one type of cellular damage occurs during the various degrees of thymine limitation. Prolonged preincubation in media containing 0.1 to 0.2 μg/ml of thymine results in an immunity to thymineless death. This immunity differs from that observed with amino acid-starved cells in its kinetics; ultraviolet irradiation of preincubated cells indicates that the cells are inactivated at the same rate as log-phase cells. These results suggest that the immunity is not associated with chromosome alignment. Thymine concentrations between 2 μg/ml and 0.2 μg/ml permit essentially the same amount of protein and RNA synthesis. The total amount of synthesis then decreases linearly to 40 to 50% of the control level with further reduction in the amount of thymine present. Protein and RNA synthesis are first affected at the same thymine concentration at which lethality is first detectable, and this correlation suggests that the synthesis of these macromolecules is involved in the mechanism of thymineless death. DNA synthesis, on the other hand, is directly dependent on the thymine concentration for levels of 0.5 μg/ml or less. There are no critical changes in DNA synthesis associated with lethality, and DNA synthesis is still occurring under conditions of thymine limitation which result in immunity. These observations suggest that DNA synthesis is not directly involved in thymineless death.
Inefficiency of Genetic Recombination in Hybrids Between
Escherichia coli
and
Salmonella typhosa
Authors: Johnson E. M. , Easterling S. B. , Baron L. S.
Published: January 2020

An
Escherichia coli
Hfr strain in which three negative chromosomal alleles (
leu
−
,
arg
−
, and
mtl
−
) were closely linked to three positive alleles (
ara
+
,
rha
+
, and
xyl
+
, respectively) was employed in matings with a
Salmonella typhosa
recipient. The detected expression of the negative
E. coli
alleles in
S. typhosa
hybrids selected for receipt of an associated positive
E. coli
marker was used to determine the occurrence of haploid
S. typhosa
recombinants, as distinguished from stable partial diploid hybrids. At the same time, the inheritance patterns and segregation behavior of the positive alleles provided indicators of the occurrence of partial diploid hybrids. Examination of both positive and negative markers inherited by
ara
+
,
rha
+
, and
xyl
−
selected
S. typhosa
hybrid classes indicated that relatively short
E. coli
chromosomal segments (generally about 4 min or less in length) were involved in recombination (haploidy), whereas rather extensive
E. coli
genetic segments were conserved in the diploid state.
S. typhosa
hybrids selected for receipt of the
ara
+
marker showed a 52% incidence of
leu
−
haploidy, which is probably close to being an accurate measure of recombination at the site of the
ara
+
allele.
S. typhosa
hybrids selected for receipt of the
rha
+
or
xyl
+
markers showed only a 20% incidence of
arg
−
or
mtl
−
haploidy, respectively, but both of these hybrid classes exhibited a higher incidence of conservation of extensive
E. coli
diploid segments than did the
ara
+
selected class. Remating of haploid
S. typhosa
hybrids with recombinant
xyl
+
mtl
−
or
rha
+
arg
−
regions resulted in higher frequencies of hybrid recovery than were observed in the initial matings. However, there was a higher incidence of partial diploidy and a lower incidence of haploidy among the hybrids obtained from these rematings.
Metabolism of
d
-Arabinose: Origin of a
d
-Ribulokinase Activity in
Escherichia coli
Authors: LeBlanc Donald J. , Mortlock Robert P.
Published: January 2020

The kinase responsible for the phosphorylation of
d
-ribulose was purified 45.5-fold from a strain of
Escherichia coli
K-12 capable of growth on
d
-arabinose with no separation of
d
-ribulo- or
l
-fuculokinase activities. Throughout the purification, the ratios of activities remained essentially constant. A nonadditive effect of combining both substrates in an assay mixture; identical

K
m

values for adenosine triphosphate with either
l
-fuculose or
d
-ribulose as substrate; and, the irreversible loss of activity on both substrates, after removal of magnesium ions from the enzyme preparation, suggest that the dual activity is due to the same enzyme. A fourfold greater affinity of the enzyme for
l
-fuculose than for
d
-ribulose, as well as a higher relative activity on
l
-fuculose, suggest that the natural substrate for this enzyme is
l
-fuculose. The product of the purified enzyme, with
d
-ribulose as substrate, was prepared. The ratio of total phosphorous to ribulose phosphate was 1.01:1, indicating that the product was ribulose monophosphate. The behavior of the kinase product in the cysteine-carbazole and orcinol reactions, as well as the results of periodate oxidation assays, provided evidence that it was not
d
-ribulose-5-phosphate. Reaction of this compound with a cell-free extract of
E. coli
possessing
l
-fuculose-l-phosphate aldolase activity resulted in the production of dihydroxyacetone phosphate and glycolaldehyde. The kinase product failed to reduce 2,3,5-triphenyltetrazolium and possessed a half-life of approximately 1.5 min in the presence of 1
n
HCl at 100 C. These properties suggested that the phosphate group was attached to carbon atom 1 of
d
-ribulose.
Differential Recovery of Auxotrophs After Penicillin Enrichment in
Escherichia coli
Authors: Rossi John J. , Berg Claire M.
Published: January 2020

Various auxotrophs are recovered from a penicillin enrichment cycle with differing efficiencies. Reconstruction experiments indicate that, under starvation conditions in the presence of penicillin, most auxotrophs undergo some death, whereas prolineless mutants are virtually immune to penicillin-induced killing.
High Dihydrofolate Reductase Levels in
Diplococcus pneumoniae
After Mutation in the Structural Gene: Biochemical and Immunological Evidence for Increased Synthesis
Authors: Sirotnak F. M.
Published: January 2020

A unique class of missense mutations in the dihydrofolate reductase structural gene of
Diplococcus pneumoniae
determines marked increases in the corresponding enzyme activity. Immunological evidence, based on precipitating and neutralizing antibody reactions, is presented in support of previously derived findings which attribute this increase in activity to an increase in the amount of enzyme protein. Biochemical evidence was obtained which shows that the increased amounts of dihydrofolate reductase protein in the mutants not owing to a decrease in degradation, reducing turnover, or to an increase in stability, and, therefore, probably related to an increase in the rate of synthesis of new protein. The manner in which a missense alteration of a structural gene might quantitatively alter the expression of that gene is discussed.
Control of Diaminopimelate Decarboxylase by
l
-Lysine During Growth and Sporulation of
Bacillus cereus
Authors: Grandgenett Duane P. , Stahly Donald P.
Published: January 2020

l
-Lysine caused repression of diaminopimelate decarboxylase synthesis in
Bacillus cereus
when grown in either a minimal defined medium (CDGS medium) or a complex defined medium (a modified lysine assay medium). When cells were grown in either of the two media, variations in the specific activity of the enzyme as a function of time were found to be correlated with the intracellular lysine pool size during growth. From all of the data presented, it seems reasonable to conclude that during growth the synthesis of diaminopimelate decarboxylase is probably regulated by the intracellular lysine pool size. The relationship between lysine pool concentration and the specific activity of the enzyme did not occur in sporulating cells. The specific activity of diaminopimelate decarboxylase started to decrease at the end of exponential growth and continued to decline until it became nondetectable at the time of dipicolinic acid synthesis and development of spore refractility. Throughout this time, the intracellular lysine pool size remained below that which allowed derepression of enzyme synthesis during exponential growth. The mechanism(s) responsible for the observed decrease in the specific activity of the enzyme at the end of exponential growth is unknown. A threefold rise in the intracellular diaminopimelic acid concentration occurred when there was little or no detectable enzyme activity at the time of dipicolinic acid synthesis. This accumulation of diaminopimelic acid may exert positive control on the synthesis of spore peptidoglycan, the major component of the spore cortex.
Suppression by Derepression in Threonine Dehydratase-Deficient Mutants of
Bacillus subtilis
Authors: Vapnek Daniel , Greer Sheldon
Published: January 2020

Partial suppressors of isoleucine-requiring mutants (Ile
−
), deficient in threonine dehydratase (TD), were studied. The suppression enables these auxotrophs to grow on the precursors homoserine or threonine as well as isoleucine. There are two genetically distinct classes of these suppressors:
sprB
, linked to threonine mutational sites, and
sprA
which is not linked to the Ile or Thr genetic region.
SprA
leads to the appearance of a low level of TD activity (2 to 4% of wild type) compared to <0.2% in Ile
−
mutants. This new TD activity is not activated by glutathione or adenosine monophosphate. Unlike the major TD, it is insensitive to inhibition by isoleucine and it is not coordinately controlled with dihydroxy acid dehydratase. Another class of auxotrophs, containing no suppressor mutation, can grow on isoleucine and homoserine or threonine because they possess structural gene mutations located near the terminus of the TD gene that result in partial impairment of TD. This TD activity (2% of wild type) is end product inhibited by isoleucine to a lesser extent than wild type TD. In this and a following paper, evidence is presented that
sprA
acts by derepressing a minor TD activity encoded within the threonine synthetic region. The major TD gene is separated from the region encoding the enzymes of threonine biosynthesis by 73% of the chromosome. Like the major TD, the minor TD catalyzes the first reaction in the conversion of threonine to isoleucine and is therefore closely related biochemically and genetically to the enzymes of the threonine synthetic region.
Cell Wall Growth in
Bacillus licheniformis
Followed by Immunofluorescence with Mucopeptide-Specific Antiserum
Authors: Hughes R. C. , Stokes Elaine
Published: January 2020

Insertion of new wall during the growth of
Bacillus licheniformis
occurred discretely and probably at the sites of incipient cross wall formation.
Demonstration of Transforming Deoxyribonucleic Acid in an Autolysate of a Group H
Streptococcus
Authors: Ranhand Jon M. , Cole Roger M.
Published: January 2020

Highly active transforming deoxyribonucleic acid was obtained from an autolysate of competent strain Wicky group H streptococcal cells that were resistant to both dihydrostreptomycin and rifampin.
Mutant of
Rhodopseudomonas spheroides
Unable to Grow Aerobically
Authors: Wittenberg T. , Sistrom W. R.
Published: January 2020

We isolated a mutant of
Rhodopseudomonas spheroides
that grows normally under photosynthetic conditions but is unable to grow exponentially under aerobic conditions. Photosynthetically grown cultures of the mutant increase in mass and cell number for about 10 hr after transfer to aerobic conditions. During this time, no heme pigments are synthesized and the Q(O
2
) declines. In the mutant, synthesis of heme pigments is obligatorily coupled to synthesis of bacteriochlorophyll.
Effect of Trimethoprim on Macromolecular Synthesis inEscherichia coli
Authors: Miovic Margaret , Pizer Lewis I.
Published: January 2020

Trimethoprim is a specific inhibitor of dihydrofolate reductase. When added to amino acid supplemented cultures ofEscherichia coli, protein, ribonucleic acid (RNA), and deoxyribonucleic acid synthesis are rapidly inhibited. It is shown that thymidylate and purine synthesis must continuously occur if the inhibition is to be maintained. These results are interpreted as demonstrating that in vivo trimethoprim can reduce but not totally inhibit the action of dihydrofolate reductase and therefore reduce the amount of tetrahydrofolate derivatives available for formylmethionyl transfer RNA formylation, purine, and thymidylate synthesis.
Dinitrophenol-Stimulated Adenosine Triphosphatase Activity in Extracts of
Desulfovibrio gigas
Authors: Guarraia Leonard J. , Peck Harry D.
Published: January 2020

A dinitrophenol (DNP)-stimulated adenosine triphosphatase (ATPase) has been found in both the soluble and particulate fractions of the anaerobic sulfate-reducing bacterium,
Desulfovibrio gigas
. As the soluble ATPase was labile to storage, only the particulate enzyme was studied in detail. It was optimally stimulated by DNP at 4 m
m
, and activity was insensitive to inhibition by ouabain. The ATPase was stimulated by both Ca
2+
and Mg
2+
, but the magnitude of the stimulation was dependent upon
p
H. In the presence of Ca
2+
the optimum
p
H was 6.5, whereas, in the presence of Mg
2+
the
p
H optimum was 8.0. However, under optimal conditions the activity was the same with either Mg
2+
or Ca
2+
. Both adenosine triphosphate and guanosine triphosphate were hydrolyzed, but activity toward guanosine triphosphate was only one-tenth that observed with adenosine triphosphate.
Transforming Ability of Bacterial Deoxyribonucleic Acid in Relation to the Marker Efficiencies in
Diplococcus pneumoniae
During Thymidine Starvation
Authors: Brunel F. , Sicard A. M. , Sicard N.
Published: January 2020

Thymidine starvation induces a decrease in transforming activity of pneumococcus deoxyribonucleic acid. The integration of low- and high-efficiency markers seems to be equally affected.