bluuebunny/crossref_metadata_2025 huggingface dataset:
Procedure for the Isolation of Mutants of
Bacillus subtilis
with Defective Cytoplasmic Membranes
Authors: Kent Claudia , Krag Sharon S. , Lennarz W. J.
Published: January 2020

A procedure has been devised to isolate mutants of
Bacillus subtilis
with structurally defective membranes. The procedure used to screen for the mutants involved comparison of the stability of protoplasts of the mutant with those of the wild type in a medium of sufficient osmotic strength to stabilize wild-type protoplasts. Mutagenized cells were grown as clones on agar plates, and then replicated onto plates containing 0.5
m
lactose, which is sufficient to stabilize wild-type protoplasts. The colonies on the lactose-containing plates were then treated with lysozyme to convert the cells to protoplasts. Colonies of wild-type protoplasts remained opaque; however, colonies of mutant protoplasts lysed and became clear. Twenty-nine osmotically fragile mutants were isolated in this manner; the membranes of several mutants were found to contain alterations in the composition of their proteins or lipids.
Novel Mutant Impaired in Cell Division: Evidence for a Positive Regulating Factor
Authors: Ingram L. O. , Fisher W. D.
Published: January 2020

A novel, conditional, cell-division mutant from
Agmenellum quadruplicatum
strain BG1 is described. During rapid growth in dilute suspensions, cell division lags behind mass increase and the cells form filaments. These filaments spontaneously divide into unit cell lengths as the culture density increases. Other conditions that favor the accumulation of metabolic products in the medium antagonize filament formations. An 80% ethanol-water extract of dried, spent medium also restores the ability of filaments to divide into cells of unit length. Our results suggest that at least one chemical factor acting as a positive effector is involved in cell division.
Genetic Recombination in Mycobacteria
Authors: Tokunaga Tohru , Mizuguchi Yasuo , Suga Kiyoko
Published: January 2020

Evidence for genetic recombination between
Mycobacterium smegmatis
strain Rabinowitchi (Rab) and strain Jucho or PM5 is presented. Backcrosses of recombinants by either parental strain indicated four different types of mating behavior, suggesting that the mycobacterial compatibilities are controlled by at least two different factors. No sex factor that transfers at a high frequency or that is sensitive to acridine dyes was detected. Analysis of segregation of unselected markers revealed that strain Jucho, or PM5, contributes the majority of alleles in almost all recombinants obtained from different selective media. Efforts to construct linkage maps for the markers employed failed because of ordering ambiguities. Mating medium containing streptomycin prevented genetic recombination when strain Rab was resistant to the antibiotic and Jucho, or PM5, was sensitive, but it did not prevent recombination when Rab was sensitive to streptomycin and Jucho, or PM5, was resistant. Very low frequency of recombinant formation was observed when Jucho, or PM5, had been treated with streptomycin, whereas recombinants were formed at fairly high frequencies when Rab had been treated with the antibiotic, suggesting that the roles of parental strains in zygote formation were not identical. The results suggest a polar transfer of genetic material from Rab to Jucho, or PM5, although an alternative possibility of cell fusion followed by exclusion could not be excluded.
Characterization of the Lipids of Six Strains of
Bacteroides ruminicola
Authors: Kunsman Joseph E.
Published: January 2020

The lipids of six strains of
Bacteroides ruminicola
were characterized. The nonpolar lipid accounted for 6 to 24% of the total lipid and was composed of diglycerides, triglycerides, and free fatty acids. The phospholipid fraction contained phosphatidylethanolamine, phosphosphingolipids, and trace quantities of phosphatidic acid. In three strains the phosphosphingolipid fraction made up more than half of the total lipid. The fatty acids in the nonpolar, acyl- and phosphosphingolipid consisted of a homologous series of branched and normal chains from 12 to 19 carbons. The long-chain base isolated from the phosphosphingolipids consisted of a homologous series of branched and normal chains from 14 to 24 carbons.
Respiration of
Bdellovibrio bacteriovorus
Strain 109J and Its Energy Substrates for Intraperiplasmic Growth
Authors: Hespell Robert B. , Rosson Reinhardt A. , Thomashow Michael F. , Rittenberg Sydney C.
Published: January 2020

Measurements of oxidation rates, respiratory quotients (RQ), and release of
14
CO
2
from uniformly labeled substrates showed that glutamate, α-ketoglutarate, and synthetic and natural amino acid mixtures are oxidized by suspensions of
Bdellovibrio bacteriovorus
strain 109J. The oxidation of these substrates largely suppress the endogenous respiration of the
Bdellovibrio
cells and may or may not cause a small increase, 20 to 50%, in their rate of oxygen consumption. The failure of respired substrates to increase markedly the respiration rate of the
Bdellovibrio
cells over the endogenous value is discussed. Carbon from these substrates is incorporated into the
Bdellovibrio
cells during oxidation. Acetate is also oxidized, but its oxidation inhibits endogenous respiration by only about 40% and no acetate is assimilated. The RQ of the
Bdellovibrio
cells changes from a value characteristic of endogenous respiration to that characteristic of the oxidation of glutamate or of a balanced amino mixture very shortly after the attack of the
Bdellovibrio
cells on their prey, and the latter RQ is maintained during intraperiplasmic growth. Glutamate, or a mixture of amino acids in the external environment, contributes to the carbon dioxide produced by the
Bdellovibrio
cells growing intraperiplasmically. It is concluded from these data that amino acids, derived from the breakdown of the protein of the prey, serve as a major energy source during intraperiplasmic growth of
B. bacteriovorus
108J. Insofar as they were tested,
B. bacteriovorus
strains 109D and A. 3. 12 were similar in respiration to strain 109J.
Involvement of Threonine Deaminase in Repression of the Isoleucine-Valine and Leucine Pathways in
Saccharomyces cerevisiae
Authors: Bollon Arthur P. , Magee P. T.
Published: January 2020

l
-Threonine deaminase (
l
-threonine dehydratase [deaminating], EC 4.2.2.16) has been shown to be involved in the regulation of three of the enzymes of isoleucine-valine biosynthesis in yeast. Mutations affecting the affinity of the enzyme for isoleucine also affected the repression of acetohydroxyacid synthase, dihydroxyacid dehydrase, and reductoisomerase. The data indicate that isoleucine must be bound for effective repression of these enzymes to take place. In a strain with a nonsense mutation midway in
liv 1
, the gene for threonine deaminase, starvation for isoleucine or valine did not lead to derepression of the three enzymes; starvation for leucine did. The effect of the nonsense mutation is recessive; it is tentatively concluded, therefore, that intact threonine deaminase is required for derepression by two of the effectors for multivalent repression, but not by the third. A model is presented which proposes that a regulatory species of leu tRNA

leu

is the key intermediate for repression and that threonine deaminase is a positive element, regulating the available pool of charged leu tRNA by binding it.
Isolation and Characterization of Thermosensitive
Escherichia coli
Mutants Defective in Deoxyribonucleic Acid Replication
Authors: Wechsler James A. , Nüsslein Volker , Otto Bernd , Klein Albrecht , Bonhoeffer Friedrich , Herrmann Richard , Gloger Lieselotte , Schaller Heinz
Published: January 2020

Thermosensitive deoxyribonucleic acid replication-defective mutants have been isolated by using an autoradiographic selection method. The mutants have been analyzed genetically and biochemically. Some of the mutants show thermosensitivity of in vitro deoxyribonucleic acid replication. These can be classified into three groups according to their behavior in in vitro complementation assays. This classification is congruent with that obtained by genetic mapping by using cotransduction frequencies with selected markers in P1 transduction analysis.
Regulation of
d
-Xylose and
d
-Arabitol Catabolism by
Aerobacter aerogenes
Authors: Wilson Bambi L. , Mortlock R. P.
Published: January 2020

Aerobacter aerogenes
strain PRL-R3 possesses inducible enzyme pathways for the catabolism of
d
-xylose and
d
-arabitol.
d
-Xylose is the apparent inducer for
d
-xylose isomerase and
d
-xylulokinase.
d
-Arabitol is the apparent inducer for
d
-arabitol dehydrogenase and a separate
d
-xylulokinase. Both kinases had similar

K
m

values and substrate specificities, and could not be separated by sucrose gradient centrifugation or polyacrylamide gel electrophoresis. They could be differentiated, however, by their separate regulation, their inhibition by antisera, and by the cold sensitivity of the kinase of the
d
-arabitol catabolic pathway.
Inducement of a Heat-Shock Requirement for Germination and Production of Increased Heat Resistance in
Bacillus fastidiosus
Spores by Manganous Ions
Authors: Aoki Hatsuo , Slepecky Ralph A.
Published: January 2020

Bacillus fastidiosus
, which requires uric acid or allantoin, grows and sporulates on a simple medium containing 59.5 mM uric acid, 5.7 mM K
2
HPO
4
, and 2% agar in distilled water. Seventy to ninety percent sporulation was achieved in 96 h. Spores obtained on this medium do not need a heat shock prior to germination. The necessary germination conditions for this organism are 30 C, phosphate or this(hydroxymethyl)aminomethane buffer at pH 7.0, and 5.95 mM uric acid. Sporulation occurred earlier (48 h) and with higher frequency (greater than 99%) when Mn
2+
was added to the growth medium. However, these spores germinated only after heat activation (70 C, 30 min). The effectiveness of heat activation was directly dependent upon the concentration of Mn
2+
in the growth medium; 10
−5
M Mn
2+
was the minimal concentration for the effect. This phenomenon was not found upon addition of Ca
2+
, Mg
2+
, Fe
2+
, Zn
2+
, or Cu
2+
to the medium. The Mn
2+
content of the spores depended upon the concentration of Mn
2+
in the sporulation medium. There was a significant difference in heat resistance between spores harvested from unsupplemented medium and those harvested from medium supplemented with 5 × 10
−5
M Mn
2+
. A
D
85 C
value of 6.5 min was determined with the former, whereas the latter had a value of 17.0 min. Very little change in either Ca
2+
or dipicolinic acid content was detected in spores harvested from various Mn
2+
-supplemented media. Thus Mn
2+
may play a role in the inducement of the heat-shock requirement and the formation of spores with increased heat resistance.
Binding of Radioactive Benzylpenicillin to Asporogenous Mutants of
Bacillus subtilis
During Postexponential Growth
Authors: Rogolsky Marvin , Lawrence Paul J. , Hanh Vo Thi
Published: January 2020

The specific penicillin binding capacity of a postexponential culture of
Staphylococcus aureus
remains constant, but that of a sporulating
Bacillus subtilis
culture fluctuates dramatically. An initial decrease in binding capacity during presporulation events is followed by two distinct intervals of enhanced specific binding capacity during the postlogarithmic growth of a sporulating
B. subtilis
culture. The first peak of enhanced binding occurs during septation, when enzymes for germ cell wall formation are present; and the second peak coincides with cortical biosynthesis. The specific postlogarithmic binding capacities of a number of Spo
−
mutants of
B. subtilis
were examined to ascertain if specific asporogenous mutations altered the binding pattern observed with the wild-type organism. Four distinct postexponential binding patterns were recognized: (i) a low, constant binding capacity resembling the binding pattern of
S. aureus
, (ii) a decrease in binding capacity with no subsequent significant peaks, (iii) a decrease in binding capacity followed by a single peak corresponding to the first peak seen with the wild type, (iv) a pattern similar to the wild type. The fourth pattern was observed in a mutant blocked during stage III of sporogenesis which produced forespores that never became refractile. Mutations blocking either one or both periods of enhanced postlogarithmic binding were interspersed throughout a linkage group of spore genes next to
lys-2
on the
B. subtilis
chomosome.
Pyridine Nucleotide-Dependent Glucose Dehydrogenase Activity in Blue-Green Algae
Authors: Pulich Warren M. , Baalen Chase Van
Published: January 2020

Pyridine nucleotide-dependent glucose dehydrogenase activity (GPND) is described for the first time in cell-free extracts of certain blue-green algae. When glucose is added to these crude cell extracts, nicotinamide adenine dinucleotide phosphate is reduced at twice the rate as nicotinamide adenine dinucleotide; but evidence suggests that this activity is due to a single enzyme. The distribution and level of GPND in selected blue-green algae correlates with the heterotrophic potential of each species. In all blue-green algae where GPND was detected, O
2
uptake coupled to the GPND reaction was also observed. Both GPND and O
2
uptake apparently occur in the soluble fraction of the cell. An essential role for GPND in the heterotrophic metabolism of blue-green algae is postulated.
Fraction of Ribosomes Synthesizing Protein as a Function of Specific Growth Rate
Authors: Harvey R. J.
Published: January 2020

The fraction of ribosomes engaged in protein synthesis in
Escherichia coli
growing at specific growth rates ranging from 0.3 to 1.2 h
−1
was estimated from measurements of nascent protein/ribosome and of polyribosomes. Both measurements showed that the fraction of ribosomes synthesizing protein increased with specific growth rate, from 30 to 70% over the range studied. Polyribosome measurements made at different specific growth rates in four
E. coli
strains showed no significant differences between strains. The increase in the fraction of polyribosomes had begun within 30 s after a shift-up from glucose-minimal medium, and was complete within 2 to 5 min. These results indicate that the function of ribosomes is regulated.
Deoxyribonucleic Acid Repair in a Highly Radiation-Resistant Strain of
Salmonella typhimurium
Authors: Davies Roland , Sinskey Anthony J. , Botstein David
Published: January 2020

Deoxyribonucleic acid repair was studied in gamma-irradiated wild-type
Salmonella typhimurium
and in a radiation-resistant derivative 20 times more resistant than wild type. After exposure to 20 or 50 krad, the wild-type strain (DB21) degraded 30 to 50% of its prelabeled DNA into acid-soluble fragments, whereas the radioresistant strain degraded less than 15% after 4 h of incubation. Post-irradiation synthesis of DNA in the wild-type strain DB21 was reduced after a dose of 20 krad and totally inhibited after exposure to 200 krad. With radiation-resistant strain, D21R6008, on the other hand, DNA synthesis was delayed after a dose of 200 krad but not inhibited. Doses of 20 and 200 krad produced a similar number of single-strand breaks in the DNA of both strains as determined by zone sedimentation analysis in alkaline sucrose gradients. The radiation-resistant strain D21R6008, on the other hand, DNA synthesis was strand breaks in its DNA and repairs these damages more rapidly than wild-type
Salmonella
.
Extrachromosomal Deoxyribonucleic Acid in Different Enterobacteria
Authors: Christiansen C. , Christiansen Gunna , Bak A. Leth , Stenderup A.
Published: January 2020

Eighty-seven different enterobacteria and pseudomonas strains were examined for the presence of extrachromosomal deoxyribonucleic acid (DNA). Thirty-four strains contained closed circular DNA by the ethidium bromide CsCl density technique. Extrachromosomal DNA was most frequent in
Escherichia
and
Klebsiella
strains. The extrachromosomal DNA was isolated and characterized by analytical ultracentrifugation and electron microscopy. All the extrachromosomal DNA-containing bacteria contained circular DNA molecules of small size (0.5–4 μm). Most of these bacteria also contained larger circles (20–40 μm). The number of different size classes of circular DNA in each strain varied from one to five. The buoyant density of the extrachromosomal DNA ranged from 1.692 to 1.721 g/cm
3
. Many bacteria contained extrachromosomal DNA of more than one density.
Fatty Acid Compositions of Paracolons:
Arizona, Citrobacter
, and
Providencia
Authors: Machtiger Neal A. , O'Leary William M.
Published: January 2020

The fatty acid compositions of stationary-phase cultures of
Arizona arizonae, Citrobacter freundii, Providencia alcalifaciens, Providencia stuartii
, and
Providencia
sp. were studied. The major fatty acids of
A. arizonae, C. freundii
, and
Providencia
were 16:0, 16:1, 17:cyclopropane, and 19:cyclopropane. The fatty acid compositions of the two strains of
A. arizonae
examined were similar to each other, but the three strains of
C. freundii
differed from one another in their fatty acid compositions. In both
A. arizonae
and
C. freundii
, the relative quantities of saturated, unsaturated, and cyclopropane fatty acids were similar to those which have been found in stationary-phase cultures of other members of the
Enterobacteriaceae
. The three strains of
Providencia
also differed from one another in their fatty acid compositions. In all three strains, the total quantity of unsaturated fatty acids was larger and that of the cyclopropane fatty acids was smaller than those found in stationary-phase cultures of other enteric bacteria.
Mutations Affecting Gluconate Metabolism in
Escherichia coli
Authors: Zwaig Rosa Nagel de , Zwaig Noé , Istúriz Tomás , Sánchez Reina S.
Published: January 2020

A mutant of
Escherichia coli
K-12 that does not ferment gluconate on fermentation plates was isolated and characterized. This mutant, designated M2, shows a long lag for growth on gluconate mineral medium and somewhat reduced levels of high-affinity transport, gluconokinase, and gluconate-6-P dehydrase activities in the log phase of growth. The mutation involved is near
malA
. Deletion mutants in which
malA
region was affected were also studied. They were found to affect the function of different genes involved in gluconate metabolism.
Minicells of
Bacillus subtilis
Authors: Reeve John N. , Mendelson Neil H. , Coyne Sheila I. , Hallock Linda L.
Published: January 2020

After nitrosoguanidine (
N
-methyl-
N
′-nitro-
N
-nitrosoguanidine) mutagenesis, two
Bacillus subtilis
mutants (
div IV-A1
and
div IV-B1
) were isolated that are defective in the location of division site along cell length. Both mutations were transferred into strain CU403 by transformation, and their properties were studied in the CU403 genetic background. Location of divisions in close proximity to cell pole regions in both mutants results in minicell production. Purified minicells contain a ratio of ribonucleic acid to protein comparable to that found in the parent cells. Autoradiographs of
3
H-thymine incorporation into deoxyribonucleic acid (DNA), thymine-
2
-
14
C
incorporation into DNA, electron micrographs, and chemical analyses for DNA all fail to demonstrate DNA in the minicells. Minicells produced by both mutants are highly motile, an indication of functional energy metabolism. Electron micrographs reveal that minicells are produced by a structurally normal division mechanism and that minicells contain a normal cell surface. The
div IV-A1
mutation has been mapped by PBS1 transduction linked to
ura
. The
div IV-B1
mutation is closely linked to
pheA
by both PBS1 transduction and by co-transformation.
Properties of a Fructose-1, 6-Diphosphate-Activated Lactate Dehydrogenase from
Acholeplasma laidlawii
Type A
Authors: Neimark Harold , Tung Ming C.
Published: January 2020

Acholeplasma laidlawii
A possesses a nicotinamide adenine dinucleotide (NAD)-dependent
l
(+)-lactate dehydrogenase (LDH) which is activated specifically by low concentrations of fructose-1, 6-diphosphate (FDP). Studies with partially purified enzyme show that the kinetic response to FDP is hyperbolic. The enzyme is inhibited by inorganic phosphate, adenosine triphosphate, and high concentrations of reduced NAD (NADH). Low activity is demonstrable in the absence of FDP at pH 6.0 to 7.2, but FDP is absolutely required in the region of pH 8. FDP causes an upward shift in the optimum pH of the enzyme, which is near 7.2 in tris (hydroxymethyl)aminomethane buffer. Activation of the enzyme by FDP is markedly affected by substrate concentration; FDP lowers the apparent

K
m

for pyruvate and NADH. The affinity of the enzyme for pyruvate is also influenced by H
+
concentration. The pyruvate analogue α-ketobutyrate serves as an effective substrate for the enzyme; when it is utilized, the enzyme is still activated by FDP. Reversal of the pyruvate reduction reaction catalyzed by the enzyme can be demonstrated with the 3-acetylpyridine analogue of NAD. The catalytic properties of the
A. laidlawii
enzyme and the known FDP-activated LDHs which occur among lactic acid bacteria are discussed.
Genetic Mutations Affecting the Respiratory Electron-Transport System of the Photosynthetic Bacterium
Rhodopseudomonas capsulata
Authors: Marrs Barry , Gest Howard
Published: January 2020

Alternative energy-converting systems permit the nonsulfur purple photosynthetic bacterium
Rhodopseudomonas capsulata
to grow either with light or (dark) respiration as the source of energy. Respiratory mutants, unable to grow aerobically in darkness, can be readily isolated and the defective step(s) in their respiratory mechanisms can be identified by study of biochemical activities in membrane fragments derived from photosynthetically grown cells. Such analysis of appropriate mutants and revertants permits construction of a model for the respiratory electron-transport system of the wild type. The results obtained indicate differential channeling of electrons derived from succinate and reduced nicotinamide adenine dinucleotide, and are interpreted in terms of a branched electron-transport scheme. The scheme provides a guide for further, more refined analysis of the respiratory mechanisms through biochemical genetic approaches, and several of the mutants isolated can be exploited for investigation of unsolved problems relating to interactions between respiratory and photosynthetic electron transport and the mechanism of inhibition of bacteriochlorophyll synthesis by molecular oxygen.
Analysis of
Halobacterium halobium
Gas Vesicles
Authors: Krantz Mark J. , Ballou Clinton E.
Published: January 2020

Gas vesicles, isolated from lysed
Halobacterium halobium
cells, gave an amino acid analysis which accounted for 78% of the weight, and the balance was mainly salt and water. One percent of tightly bound
d
-galactose was found, as well as 2% of phosphate that was not released by treatment which promotes β-elimination, by hydrolytic release of the galactose, by carboxymethylation of lysine, or by alkaline phosphatase digestion. Only a trace of lipid was detected, and it appeared to have a polyisoprenoid structure. The vesicles were not solubilized by extremes of pH, by agents such as urea, guanidine hydrochloride, formic acid, and detergents, or by organic solvents. Succinylation and carboxymethylation gave partial dispersion, but the products were heterogeneous and of high molecular weight. The amino acid composition of vesicles was independent of fragment size. No band was obtained by polyacrylamide gel electrophoresis, with neutral, acidic, and alkaline systems, with or without sodium dodecyl sulfate and urea, before or after chemical modification. No amino terminus was detected. Electrofocusing of a vesicle dispersion showed a major component with a pI of 4.0 and an amino acid composition of the whole vesicles, and a minor band with pI 3.4 which had an amino acid composition different from whole vesicles. Vesicle protein was resistant to digestion by Pronase, trypsin, thermolysin, and papain. The precipitin reaction with rabbit antivesicle serum was not inhibited by galactose or inorganic phosphate. Succinylated and carboxymethylated vesicles cross-reacted with antivesicle serum. Cell lysates contained material which reacted with antiserum, but it was heterogeneous and mainly larger than 5 × 10
6
daltons. Material from nonvacuolated mutants reacted weakly with antiserum, but the amino acid composition of the precipitated antigen was different from that of vesicles and of soluble cross-reacting material from vacuolated cells.
Trisporic Acid Biosynthesis in Separate Plus and Minus Cultures of
Blakeslea trispora
: Identification by
Mucor
Assay of Two Mating-Type-Specific Components
Authors: Sutter Richard P. , Capage Domenick A. , Harrison Thomas L. , Keen William A.
Published: January 2020

Separate plus and minus cultures of
Blakeslea trispora
synthesize small amounts of trisporic acids under specific conditions. These amounts are expressed as a percentage of the trisporic acids (50 mg/liter of medium) synthesized by mixed plus-minus cultures in 5 days. Plus cultures, without additives from minus cultures, synthesize 0.1% trisporic acids. Plus cultures synthesize 0.4% trisporic acids when stimulated by M-factor, a mating-type-specific component synthesized by minus cultures. Minus cultures, without additives from plus cultures, do not synthesize even 0.0001% trisporic acids. Minus cultures synthesize 1% trisporic acids when stimulated by P-factor, a mating-type-specific component synthesized by plus cultures. Minus cultures synthesize M-factor when stimulated by π, a component synthesized by plus cultures. We speculate that (i) minus cultures synthesize a component, μ, which stimulates P-factor synthesis in plus cultures, and (ii) both M-factor and P-factor are precursors of trisporic acids.
Lipid Synthesis During Sporulation of
Saccharomyces cerevisiae
Authors: Henry Susan A. , Halvorson H. O.
Published: January 2020

Lipid synthesis was studied in both sporulating (diploid) and nonsporulating (haploid) cells of
Saccharomyces cerevisiae
. Two phases of lipid synthesis occur in diploid cells transferred to sporulation medium. Phase I, which occurs during the first 12 h of exposure to sporulation medium, was also observed in the haploid strains. Phase II, occurring from the 20th to the 25th h, coincided with the appearance of mature asci and was observed only in the diploid cells. The majority of phospholipid synthesis took place during period I, whereas neutral lipid synthesis occurred during both periods. Phospholipid synthesis was virtually identical in both type and quantity in the sporulating and nonsporulating strains.
Internal Membrane Control in
Azotobacter vinelandii
Authors: Pate Jack L. , Shah Vinod K. , Brill Winston J.
Published: January 2020

Azotobacter vinelandii
was grown on N
2
, NH
4
+
, or NO
3
−
, and an internal membrane network was observed by electron microscopy of thin sections of cells. Cells obtained in early exponential growth contained less internal membrane than did cells from cultures in late exponential growth. It seems likely that O
2
has a role in regulating the amount of internal membrane structure.
Regeneration of Invertase in
Neurospora crassa
Authors: Marzluf George A.
Published: January 2020

In
Neurospora
, invertase is predominately an extracellular enzyme, and acid phosphatase is partially external in location. Both extracellular invertase and acid phosphatase were rapidly and quantitatively inactivated by acid treatment (pH 1.3). When such acid-treated cells were incubated with a suitable carbon source, a substantial regeneration of invertase activity occurred, but no restoration of acid phosphatase could be detected. The regeneration of invertase does not occur by renaturation of the inactivated enzyme, nor by secretion of a preexisting intracellular pool of invertase, but instead requires de novo enzyme synthesis. Invertase synthesis was partially repressed by glucose and mannose and was completely inhibited by 2-deoxyglucose. Acetate was found to inhibit invertase regeneration and the transport and incorporation of uracil and leucine. Several potential inhibitors of transcription, including alpha-amanitin, 5-fluorouracil, actinomycin D, and three derivatives of rifamycin, were ineffective in preventing invertase regeneration and in inhibiting the synthesis of ribonucleic acid. Conidia appeared to be very poorly permeable to these compounds.
Control of Arginine Biosynthesis in
Escherichia coli:
Inhibition of Arginyl-Transfer Ribonucleic Acid Synthetase Activity
Authors: Williams A. L. , Yem D. W. , McGinnis E. , Williams L. S.
Published: January 2020

In this study, we have extended our earlier observations indicating in vitro inhibition of arginyl-transfer ribonucleic acid synthetase (EC 6.1.13, arginine: soluble ribonucleic acid ligase, adenosine monophosphate) activity by the arginine biosynthetic precursors ornithine, citrulline, and argininosuccinate. Furthermore, we report evidence which suggest that this enzyme activity is inhibited by these arginine precursors in vivo and that this inhibition of activity results in a derepression of arginine biosynthesis.
Scanning Electron Microscopy of Colonies of Six Species of
Candida
Authors: Joshi K. R. , Wheeler E. E. , Gavin J. B.
Published: January 2020

Thirty strains of six species of
Candida
isolated from patients were cultured for 60 h on Sabouraud agar, freeze-dried, and examined with a scanning electron microscope. The colonies were circular (
Candida albicans, C. guilliermondii
) or oval (
C. tropicalis, C. pseudotropicalis, C. krusei, C. parakrusei
) in outline, and those of
C. pseudotropicalis
and
C. krusei
had an irregular outline due to a peripheral pseudomycelium. The morphology of individual microorganisms was examined at the margins and apex of those species which lacked a surface coat (
C. pseudotropicalis, C. krusei, C. parakrusei, C. guilliermondii
), and through cracks in the surface coating of those which showed a surface coat (
C. albicans, C. tropicalis
). All species showed buds, bud scars, and interconnecting intercellular processes, but were generally spherical (
C. albicans, C. tropicalis
) or ovoid (
C. pseudotropicalis, C. krusei, C. parakrusei, C. guilliermondii
) in fixed preparations. In unfixed material, individual organisms were almost invariably indented. Fixation with 3% glutaraldehyde and washing before freeze-drying caused partial removal of the surface coating of colonies of
C. albicans
and
C. tropicalis
, which persisted only as irregular sheets or as a filamentous meshwork. This filamentous meshwork was also present among the organisms of colonies of
C. albicans, C. tropicalis
, and
C. pseudotropicalis
. It is concluded that these filaments represent the precipitation or unmasking of some component of the intercellular matrix of these organisms.
Unusual Arsenate Poisoning of the F Pili of
Escherichia coli
Authors: O'Callaghan R. J. , Bundy Linda , Bradley R. , Paranchych W.
Published: January 2020

The arsenate poisoning of R17 phage eclipse in
Escherichia coli
cultures grown in glycerol-containing medium has been found to be mediated by a dramatic loss in cell-associated F pili. Poisoning was very rapid and was nearly complete within 3 min at 37 C. The loss of pili was reflected by a 90% reduction in the ability of these cells to attach ribonucleic acid phage and by a reduction in the pili-per-cell ratio from 1.36 to 0.04 as determined by electron microscopy. Neither the integrity of the pilus per se nor the attachment process was affected by arsenate, for cell-free pili treated with arsenate retained the ability to attach phage. The arsenate effect on F piliation could be reversed readily without any loss in cell viability. This restoration of pili occurred under conditions of inhibited protein synthesis, implying that pools of pili protein exist in cells. In contrast to this phenomenon, cells grown in glucose-containing media were mainly resistant to arsenate poisoning as determined by phage attachment and the number of pili per cell. These results implied that arsenate poisons the ability of cells to synthesize and maintain F pili under certain specific conditions. The possible mechanism of this poisoning is discussed.
Respiratory Development in
Saccharomyces cerevisiae
Grown at Controlled Oxygen Tension
Authors: Rogers P. J. , Stewart P. R.
Published: January 2020

Saccharomyces cerevisiae
was grown in batch culture over a wide range of oxygen concentrations, varying from the anaerobic condition to a maximal dissolved oxygen concentration of 3.5 μM. The development of cells was assayed by measuring amounts of the aerobic cytochromes
aa
3
,
b, c
, and
c
1
, the cellular content of unsaturated fatty acids and ergosterol, and the activity of respiratory enzyme complexes. The half-maximal levels of membrane-bound cytochromes
aa
3
,
b
, and
c
1
, were reached in cells grown in O
2
concentrations around 0.1 μM; this was similar to the oxygen concentration required for half-maximal levels of unsaturated fatty acid and sterol. However, the synthesis of ubiquinone and cytochrome
c
and the increase in fumarase activity were essentially linear functions of the dissolved oxygen concentration up to 3.5 μM oxygen. The synthesis of the succinate dehydrogenase, succinate cytochrome
c
reductase, and cytochrome
c
oxidase complexes showed different responses to changes in O
2
concentration in the growth medium. Cyanide-insensitive respiration and P
450
cytochrome content were maximal at 0.25 μM oxygen and declined in both more anaerobic and aerobic conditions. Cytochrome
c
peroxidase and catalase activities in cell-free homogenates were high in all but the most strictly anaerobic cells.
Isolation of Assimilatory- and Dissimilatory-Type Sulfite Reductases from
Desulfovibrio vulgaris
Authors: Lee Jin-Po , LeGall Jean , Peck Harry D.
Published: January 2020

Bisulfite reductase (desulfoviridin) and an assimilatory sulfite reductase have been purified from extracts of
Desulfovibrio vulgaris
. The bisulfite reductase has absorption maxima at 628, 580, 408, 390, and 279 nm, and a molecular weight of 226,000 by sedimentation equilibrium, and was judged to be free of other proteins by disk electrophoresis and ultracentrifugation. On gels, purified bisulfite reductase exhibited two green bands which coincided with activity and protein. The enzyme appears to be a tetramer but was shown to have two different types of subunits having molecular weights of 42,000 and 50,000. The chromophore did not form an alkaline ferrohemochromogen, was not reduced with dithionite or borohydride, and did not form a spectrally visible complex with CO. The assimilatory sulfite reductase has absorption maxima at 590, 545, 405 and 275 nm and a molecular weight of 26,800, and appears to consist of a single polypeptide chain as it is not dissociated into subunits by sodium dodecyl sulfate. By disk electrophoresis, purified sulfite reductase exhibited a single greenish-brown band which coincided with activity and protein. The sole product of the reduction was sulfide, and the chromophore was reduced by borohydride in the presence of sulfite. Carbon monoxide reacted with the reduced chromophore but it did not form a typical pyridine ferrohemochromogen. Thiosulfate, trithionate, and tetrathionate were not reduced by either enzyme preparation. In the presence of 8 M urea, the spectrum of bisulfite reductase resembles that of the sulfite reductase, thus suggesting a chemical relationship between the two chromophores.
d
-Alanine Oxidase from
Escherichia coli
: Participation in the Oxidation of
l
-Alanine
Authors: Raunio R. P. , Straus L. D'ari , Jenkins W. T.
Published: January 2020

Cell wall-membrane preparations of
Escherichia coli
, prepared by the ethylenediaminetetraacetic acid-lysozyme method, contain enzymes which catalyze the oxidation of
d
-alanine and, to a lesser extent,
l
-alanine into pyruvate and ammonia without the formation of hydrogen peroxide. The kinetic parameters were (i) pH optima of 8.3 to 8.4 for
l
- and
d
-alanine and (ii) a

K
m

value of 6.6 ± 0.2 mM for
d
-alanine. Several coenzymes were without effect when added to the reaction mixture. The participation of
d
-alanine oxidase in the oxidation of
l
-alanine was demonstrated. The evidence is based on (i) results of cellular fractionation; (ii) labeling experiments; (iii) inhibition studies with aminooxyacetate and cycloserine; (iv) denaturation experiments; and (v) demonstration of the presence of an active racemase.
Activity and Heat Stability of Trehalase from the Mycelium and Ascospores of
Neurospora
Authors: Hecker Lanny I. , Sussman Alfred S.
Published: January 2020

Trehalases from the ascospores of
Neurospora tetrasperma
and the mycelium of
N. crassa
were compared. Enzymes from both sources have identical electrophoretic mobilities,

K
m

's, responses to pH, immunological reactions, and activities in low-molarity buffers. Because both enzymes are so similar, conclusions about the properties of the ascospore enzyme may, be made by studying mycelial trehalase. Mycelial trehalase is most active and stable in low-molarity buffers. The enzyme exists in at least three species; the smallest has a molecular weight between 105,000 and 125,000 and is predominant in low-molarity buffers at 37 C. The stability of trehalase to heating at 65 C can be increased by increasing enzyme concentration and by the addition of polyols. Ascospores contain large amounts of trehalose, which protects trehalase from heat inactivation at 65 C. The importance of this phenomenon in vivo and its relationship to the localization of trehalase in ascospores is discussed.
Tryptophan Metabolism and Kynureninase Induction in Mutants of
Neurospora crassa
Resistant to 4-Methyl-Tryptophan
Authors: Turner J. R.
Published: January 2020

Mutants of
Neurospora crassa
that are resistant to 4-methyl-tryptophan were found to differ in ability to synthesize kynureninase in the presence of the inducers kynurenine, 3-OH-kynurenine,
N
-formyl-kynurenine, tryptophan, and indole. One strain (
mtr26
), although incapable of accumulating intracellular pools of these compounds, showed induced synthesis of kynureninase, whereas the second (
mtr21
) could neither accumulate nor be induced by them. Strain
mtr21
, with the suppressor
su
(
mtr
), could not be induced by indole but was induced by tryptophan and kynurenine derivatives. These results suggest that the
mtr
mutation, in addition to altering the ability of these strains to concentrate tryptophan and its metabolites, may have some effect on either the intracellular distribution of tryptophan or directly on the synthesis of kynureninase.
Genetic Analysis of the System that Reduces Biotin-
d
-Sulfoxide in
Escherichia coli
Authors: Dykhuizen Daniel
Published: January 2020

Four genes of
Escherichia coli
whose products are needed to reduce biotin-
d
-sulfoxide to biotin have been mapped:
bisA
next to
chlA, bisB
next to
chlE, bisC
linked to
xyl
, and
bisD
next to
chlG
. A defective λ transducing phage, λ
dbis5
, which carries all the bacterial genes between the λ attachment site and
chlE
, was isolated and shown to have lost the phage genes from
int
through
Q
.
Studies on the Developmental Cycle ofChlamydia trachomatis: Isolation and Characterization of the Initial Bodies
Authors: Gutter Bezalel , Asher Yael , Cohen Yafa , Becker Yechiel
Published: January 2020

The initial bodies which develop in the inclusion bodies of trachoma agent (Chlamydia trachomatis) were separated from the infected cells nuclei and cytoplasmic components by zone centrifugation in sucrose gradients. The initial bodies are the site of the agent's ribonucleic acid synthesis and serve as precursors to the elementary bodies. The conversion of the initial bodies to elementary bodies is through a process which resembles binary fission. The effects of antibiotics on the development of the trachoma agent initial bodies revealed that rifampin prevented and hydroxyurea affected the formation of the initial bodies. Penicillin led to the formation of structures larger than the initial bodies.
Solubilization of the Cytoplasmic Membrane of
Escherichia coli
by the Ionic Detergent Sodium-Lauryl Sarcosinate
Authors: Filip Camille , Fletcher Gail , Wulff Judith L. , Earhart C. F.
Published: January 2020

The sensitivity of the outer and cytoplasmic membranes of
Escherichia coli
to detergent was examined by isopycnic sucrose density gradient centrifugation. Sodium lauryl sarcosinate (Sarkosyl) was found to disrupt the cytoplasmic membrane selectively under conditions in which Triton X-100 and dodecyl sodium sulfate solubilized all membrane protein. These results were verified by gel electrophoresis; membrane proteins solubilized by Sarkosyl were identical to those of the cytoplasmic membrane. The presence of Mg
2+
during treatment with Sarkosyl was found to afford partial protection of the cytoplasmic membrane from dissolution.
Genetic and Biochemical Characterization of Mutants of
Bacillus subtilis
Defective in Succinate Dehydrogenase
Authors: Ohné Margareta , Rutberg Blanka , Hoch James A.
Published: January 2020

Eleven succinate-accumulating mutants of
Bacillus subtilis
have been mapped by transformation and transduction crosses and characterized with respect to activities of citric acid cycle enzymes. These mutants could be divided into three genetic groups. Nine of the mutants were found to map between
argA
and
leu
in the
citF
locus. A second group was located between
lys-1
and
trpC2
and the third group could not be located on the
B. subtilis
chromosome in extensive transduction crosses. All of the
citF
mutants lack detectable succinate dehydrogenase activity, whereas both of the other groups show a reduced level of this enzyme. In addition, most of the mutants in the
citF
locus lack cytochrome
a
, whereas the level of this cytochrome is normal in the other two groups. A procedure has been devised for the solubilization of the succinate dehydrogenase from the membrane of
B. subtilis
with the non-ionic detergent Brij 58. Some properties of the soluble and bound forms of succinate dehydrogenase are described.
Mutation in
Neurospora crassa
Affecting Some of the Extracellular Enzymes and Several Growth Characteristics
Authors: Murayama Tadako , Ishikawa Tatsuo
Published: January 2020

A mutant of
Neurospora crassa
, strain T9, which shows reduced activity of glucoamylase, was isolated. The mutant glucoamylase was not altered in pH optimum, or thermostability, but altered in elution profile of Bio-Gel filtration. The T9 mutation led to other distinct phenotypic effects: a poor growth response, resistance to the effect of sorbose, a high activity of extracellular acid phosphatase, and an increased sensitivity to high osmolarity of the growth medium. The discussion was based on the idea that the T9 mutation occurred at a gene governing the synthesis of cell wall precursors and resulted in an alteration in various characteristics related to extracellular enzymes and growth.
Deoxyribonucleic Acid-Dependent Ribonucleic Acid Polymerase of
Caulobacter crescentus
Authors: Bendis Ina K. , Shapiro Lucille
Published: January 2020

Deoxyribonucleic acid-dependent ribonucleic acid (RNA) polymerase (EC 2.7.7.6) was purified from the dimorphic bacterium
Caulobacter crescentus
at three stages in development. Enzyme from pure populations of stalked cells, as well as populations enriched in swarmer and predivisional cells, appeared identical in subunit structure and template requirements. The molecular weights of the enzyme subunits were 165,000, 155,000, 101,000, and 44,000, respectively. By analogy with RNA polymerase from other bacterial sources, they are considered to be components of the
C. crescentus
holoenzyme, β′, β, σ, and α, respectively. The
C. crescentus
enzyme appeared similar to the
Pseudomonas aeruginosa
enzyme and unlike the
Escherichia coli
enzyme with respect to subunit molecular weights and failure to separate into core and sigma components upon phosphocellulose chromatography. In addition, the effects of ionic strength on the time course of polymerization varied both with the sources of bacterial polymerase and bacteriophage DNA.
Studies on Mitochondrial Membrane Proteins in
Saccharomyces cerevisiae
under Different Degrees of Glucose Repression
Authors: Mian Fayyaz A. , Küenzi Martin T. , Halvorson Harlyn O.
Published: January 2020

Mitochondrial membrane proteins synthesized in vivo in the presence of cycloheximide were analyzed on electrofocusing polyacrylamide gels. Five of the six protein bands observed have their isoelectric points below pH 7. The six proteins are not synthesized when both cycloheximide and chloramphenicol are present, and they are absent in a petite mutant lacking mitochondrial deoxyribonucleic acid (DNA), leading to the conclusion that the proteins are synthesized on mitochondrial ribosomes. By labeling cells of
Saccharomyces cerevisiae
cultivated in a chemostat under different degrees of glucose limitation, the effect of glucose repression on the synthesis of the mitochondrial membrane proteins was determined. Two of the protein bands showed a relatively reduced synthesis under the strongest glucose repression tested. The specific activity of the cytochrome oxidase and the percentage of mitochondrial DNA in the total DNA were found to be influenced at a lower level of glucose repression.
Cell-Bound Thiaminase I ofBacillus thiaminolyticus
Authors: Agee C. Coe , Wilkins Judy H. , Airth R. L.
Published: January 2020

The distribution of the extracellular enzyme, thiaminase I, was determined for logarithmically growing cultures ofBacillus thiaminolyticus. About 60% of the enzyme is associated with the cells throughout the growth cycle. The remainder of the enzyme is in the culture medium. The release of the cell-bound thiaminase I is examined under a variety of conditions. The rate and extent of release is dependent on the pH and the nature of the incubation solution. The release process appears to be relatively independent of de novo protein synthesis, energy derived from oxidative phosphorylation, or divalent metal ions. The absence of carbon or nitrogen sources has little effect on the release of the enzyme. Cell-bound thiaminase I probably is the immediate precursor for extracellular thiaminase I found in the culture medium. Washed cells continue to release thiaminase I at the expense of cell-bound enzyme. In addition, purified cell-bound thiaminase I is indistinguishable from purified extracellular thiaminase I by a number of physical and kinetic criteria.
Genetic Analysis of Bacteriophage Mu-Induced Flagellar Mutants in
Escherichia coli
Authors: Silverman Michael , Simon Melvin
Published: January 2020

In previous work, at least 10 discrete cistrons involved in the synthesis of flagella in
Escherichia coli
were described. Six cistrons were located between
his
and
uvrC
on the genetic map. These were referred to as
hag, flaA, flaB, flaC, flaD
, and
flaE
. Four cistrons referred to as
mot, flaG, flaH
, and
flaI
were located between
uvrC
and
aroD
. In order to determine whether these genes are organized into transcriptional units, a series of Mu phage-induced flagellar mutants was studied. The mutant strains behaved as if they were carrying strong polar mutations. Of 228 independent Mu-induced mutants, 114 with mutations in the
his-aroD
region of the genetic map were tested by preparing partial diploid strains with episomes carrying a variety of previously defined mutations. The pattern of complementation that emerged indicated that cistrons
flaB, flaC
, and
flaE
form a transcriptional unit. Cistron
flaO
, defined in the course of this study, is also a member of this transcriptional unit. The order of transcription is
B-C-O-E. flaA
was found to be complex, and it included four cistrons,
flaA, flaP, flaQ
, and
flaR
, with the transcriptional order
A-P-Q-R
. Cistrons
flaG
and
flaH
are cotranscribed with the transcriptional order
G-H
. The remaining genes,
flaD, flaI, hag
, and
mot
do not belong to multicistronic transcriptional units. Complementation analysis suggested that the
cheC
locus is the same as cistron
flaA
.