bluuebunny/crossref_metadata_2025 huggingface dataset:
Glucose-dependent Secretion and Destruction of Hydrogen Peroxide by
Mycoplasma pneumoniae
Authors: Cohen Gerald , Somerson Norman L.
Published: January 2020

The secretion of H
2
O
2
by
Mycoplasma pneumoniae
and
M. gallisepticum
was measured with the new catalase-aminotriazole method. Peroxide secretion by the mycoplasmas was stimulated by glucose. When catalase and aminotriazole were omitted and exogenous H
2
O
2
was added to the mycoplasmas, a loss in H
2
O
2
was noted with time; the addition of glucose speeded the disappearance of H
2
O
2
. The presence of this peroxidase-like activity in the mycoplasmas explains an observed failure of H
2
O
2
to accumulate freely in the suspension medium.
Genetic Analysis of the Maltose A Region in
Escherichia coli
Authors: Hatfield Dolph , Hofnung Maurice , Schwartz Maxime
Published: January 2020

The genetic map of the maltose A locus of
Escherichia coli
contains at least three closely linked genes,
malT, malP
, and
malQ
. The order of these genes is established by deletion mapping.
MalP
and
malQ
, the presumed structural genes for maltodextrin phosphorylase and amylomaltase, belong to the same operon.
MalT
may be a regulator gene involved in the positive control of this operon.
Correlation Between the Rate of Ribonucleic Acid Synthesis and the Level of Valyl Transfer Ribonucleic Acid in Mutants of
Escherichia coli
Authors: Kaplan Sam
Published: January 2020

By use of a mutant of
Escherichia coli
with a partially thermolabile transfer ribonucleic acid (tRNA) synthase, it was possible to regulate the rate of RNA synthesis over a 10-fold range. The addition of chloramphenicol to cultures kept at the nonpermissive temperature stimulated RNA synthesis. The longer the culture was kept at the nonpermissive temperature prior to addition of chloramphenicol, the lower was the resulting rate of RNA synthesis. The decrease in the rate of incorporation of labeled uracil into RNA was correlated with the decrease in the level of valyl tRNA. Additional experiments provided evidence which may be interpreted as indicating that valyl tRNA does not, by itself, react with the RNA-forming system.
Carbohydrate Accumulation and Metabolism in
Escherichia coli:
the Close Linkage and Chromosomal Location of
ctr
Mutations
Authors: Wang Richard J. , Morse Helvise G. , Morse M. L.
Published: January 2020

Six pleiotropic
ctr
mutations of
Escherichia coli
, affecting the ability to utilize 10 carbohydrates, were found to be closely linked to one another and to the mutation of strain MM6 causing lack of enzyme 1 of the phosphotransferase system. These mutations are located at 46 to 47 min on the
E. coli
map. Preliminary biochemical evidence indicates that the
ctr
mutants also lack enzyme 1, although they have a different phenotype from MM6.
Biosynthesis of Branched-Chain Amino Acids in Yeast: Regulation of Synthesis of the Enzymes of Isoleucine and Valine Biosynthesis
Authors: Bussey Howard , Umbarger H. E.
Published: January 2020

Regulation of the levels of the five enzymes required for the biosynthesis of isoleucine and valine was studied in a
Saccharomyces
sp. When a mixture of isoleucine, valine, and leucine was added to the medium, the enzymes in the wild-type strain were repressed from about 30% (transaminase B) to about 90% (acetohydroxy acid synthetase) relative to the level in minimal medium-grown cells. Repression was also observed when threonine replaced isoleucine in the mixture but not when it replaced the other two amino acids. Significant derepression relative to the level in minimal-grown cells was not obtained by growing suitably blocked auxotrophs on medium containing limiting amounts of valine, isoleucine, or leucine.
Polynucleotide Sequence Relationships among Members of
Enterobacteriaceae
Authors: Brenner Don J. , Fanning George R. , Johnson Karl E. , Citarella R. V. , Falkow Stanley
Published: January 2020

Polynucleotide relationships were examined among many representatives of the
Enterobacteriaceae
by means of agar, membrane filter, and hydroxyapatite procedures. The amount of deoxyribonucleic acid (DNA) that reassociated was dependent, especially in interspecific reactions, on the annealing temperature. In only three cases:
Escherichia coli-Shigella flexneri, Salmonella typhimurium-S. typhi
, and
Proteus mirabilis-P. vulgaris
, was relative interspecific duplex formation 80% or higher. In most cases interspecies DNA duplex formation was 40% or less of that obtained from intraspecies DNA reassociation reactions. The stability of
E. coli-S. flexneri
DNA duplexes formed at either 60 or 75 C was virtually identical to that of homologous
E. coli
DNA duplexes, and the degree of interspecies duplex formation was minimally affected by the temperature increase (86% at 60 C; 77% at 75 C). The thermal stability of DNA duplexes formed at 60 C between DNA from
E. coli
and DNA from strains of
Aerobacter aerogenes, S. typhimurium, S. typhi
, and
P. mirabilis
was about 12 to 14 C below that of reassociated
E. coli
DNA. At 75 C, the formation of the interspecific DNA duplexes was markedly decreased, but the stability of the DNA able to reassociate at this temperature approximated that of reassociated
E. coli
DNA. The degree of reassociation and the thermal stability of
E. coli-S. flexneri
DNA duplexes suggests relatively little evolutionary divergence in these organisms. The other enterobacteria tested, however, have diverged to a point where less than one-half of their DNA can reanneal with
E. coli
DNA at 60 C and less than 10% reacts at 75 C. The degree of divergence between various enterobacteria does not appear to be uniform along the DNA molecule. Ribosomal ribonucleic acid (RNA)-specific sequences are conserved among most enterobacteria. An examination of messenger RNA relatively specific for the lactose operon suggests that specific chromosomal genes may diverge more or less than the genome as a whole.
Capacity of Aspartic Acid to Increase the Bacterial Count on Suspensions of
Escherichia coli
After Freezing
Authors: Kuo Shou-Chang , MacLeod Robert A.
Published: January 2020

The addition of 2% Trypticase to a minimal salts-glucose plating medium increased the bacterial count of frozen and thawed suspensions of
Escherichia coli
451B cells, even when precautions were taken to remove toxic trace elements from the plating diluent. Hydrolysis of the Trypticase with HCl or H
2
SO
4
reduced its count-increasing activity. Treatment of the H
2
SO
4
hydrolysate with a cation-exchange resin greatly improved its capacity to replace Trypticase. Addition of a mixture of amino acids approximating the composition of casein also increased the plate count when added at a level equivalent to 0.1% casein, but at 2% it depressed the count. Tests of amino acids in the mixture revealed that aspartic acid could replace Trypticase completely as a supplement to the basal medium. When added at a level of 2.5 m
m
, aspartic acid doubled and occasionally tripled the plate count of a suspension of frozen and thawed cells. Glutamic acid, alanine, and to a lesser extent certain other amino acids also showed a capacity to increase the count. Cysteine was without significant effect. Serine and other amino acids depressed the count. None of the amino acids or other supplements affected the count of suspensions of cells that had not been frozen. The effect of adding aspartic acid, cysteine, or Trypticase to the basal medium on the bacterial count of suspensions of various strains of
E. coli, Aerobacter aerogenes, Serratia marcescens
, and two species of
Pseudomonas
after freezing was examined. The response to the supplements was unique for each organism.
Ribonucleic Acid Synthesis During the Differentiation of Sporangia in the Water Mold
Achlya
Authors: Griffin David H. , Breuker Christine
Published: January 2020

The role of ribonucleic acid (RNA) synthesis in the development of sporangia in the saprolegniaceous mold
Achlya
was studied. Methods were developed for growing and treating large populations of mycelia so that the hyphal tips would differentiate into sporangia with considerable synchrony. Under the starvation conditions imposed for the differentiation of sporangia, net RNA, deoxyribonucleic acid (DNA), and protein synthesis ceased. However, incorporation of radioactive precursors into RNA continued at a high rate throughout the period of differentiation, showing that the enzymatic mechanism for RNA synthesis was still in an active state. Actinomycin D inhibited the differentiation of sporangia and the incorporation of labeled precursors into RNA. The level of actinomycin used did not inhibit the normal outgrowth and branching of the mycelia that occurred during differentiation. Thus, DNA-dependent RNA synthesis was required for the differentiation of sporangia. Sucrose gradient analysis of newly synthesized RNA showed that only the ribosomal and soluble fractions of RNA were labeled during vegetative growth. During the differentiation of sporangia, ribosomal and soluble RNA fractions were also labeled, and, in addition, a heterodisperse fraction of labeled RNA which was heavier than ribosomal RNA appeared; this fraction was not evident in the newly synthesized RNA from vegetative mycelia.
Biochemistry of Sexual Morphogenesis in
Schizophyllum commune
: Effect of Mutations Affecting the Incompatibility System on Cell-Wall Metabolism
Authors: Wessels Joseph G. H.
Published: January 2020

A number of homokaryons of
Schizophyllum commune
, which carry various mutations affecting the incompatibility system, and a wild-type homokaryon were grown and examined for differences in the net synthesis of the cell-wall polysaccharides S-glucan, R-glucan, and chitin and in the activity of an enzyme hydrolyzing R-glucan (R-glucanase) in mycelial extracts and culture media. Only slight differences were observed for the accumulation of S-glucan and chitin. In comparison with the wild-type homokaryon, a very high S-glucan/R-glucan ratio was found in a primary
B
-factor mutant strain. Essentially, wild-type S-glucan/R-glucan ratios were restored in two strains in which additional mutations restored normal morphology: a strain carrying a secondary
B
-factor mutation and a strain carrying a modifier mutation in addition to the primary
B
-factor mutation. The S-glucan/R-glucan ratios in three
A
-factor mutants were intermediate between those of the wild-type homokaryon and the primary
B
-factor mutant. In young, growing cultures of the various homokaryons, except for the
A
-factor mutants, a correlation was found between the S-glucan/R-glucan ratios in the cell wall and the activities of R-glucanase in mycelial extracts. A certain specificity of the effect of the studied mutations on enzyme activities was indicated by the fact that, in young cultures, changes in R-glucanase activities were not paralleled by similar changes in the activities of laminarinase and maltase. The results can be correlated with particular morphological features of the homokaryons and, together with earlier results obtained with heterokaryons, indicate the activity of R-glucanase as an integral component of sexual morphogenesis regulated by the incompatibility factors.
Malate Utilization by a Group D
Streptococcus
: Physiological Properties and Purification of an Inducible Malic Enzyme
Authors: London Jack , Meyer Eleanor Y.
Published: January 2020

Growth of
Streptococcus faecalis
in the presence of
l
-malate resulted in the induction of a “malic enzyme” [
l
-malate:nicotinamide adenine dinucleotide (NAD) oxidoreductase (decarboxylating), E.C. 1.1.1.39]. Synthesis of the malic enzyme did not appear to be subject to catabolite repression by intermediate products of glucose or fructose dissimilation. However, malate utilization was inhibited during growth in the presence of glucose or fructose. The purified enzyme was specific for malate as substrate and NAD as cofactor. Mn
+2
or Mg
+2
was required for optimal activity and NH
4
Cl stimulated the reaction rate. Several lines of indirect evidence suggested that the streptococcal malic enzyme was involved primarily with energy production and not biosynthesis.
Bacteriochlorophyll and Heme Synthesis in
Rhodopseudomonas spheroides
: Possible Role of Heme in Regulation of the Branched Biosynthetic Pathway
Authors: Lascelles June , Hatch Thomas P.
Published: January 2020

Synthesis of heme, measured by incorporation of iron-59, and of bacteriochlorophyll was studied with wild-type and mutant strains of
Rhodopseudomonas spheroides
. The wild type formed heme from glycine and succinate at one-fortieth the rate of bacteriochlorophyll under anaerobic-light conditions. Added δ-aminolevulinate stimulated heme synthesis 10-fold without increasing bacteriochlorophyll production. Heme synthesis from glycine and succinate was increased when the magnesium branch of the biosynthetic path was curtailed by mutation or by
p
-fluorophenylalanine or 8-azaguanine. Synthesis of bacteriochlorophyll by the wild type from glycine and succinate stopped immediately after addition of puromycin, but heme production continued for a period. Porphyrins and other precursors did not appear upon addition of puromycin alone, but simultaneous addition of
o
-phenanthroline resulted in the accumulation of coproporphyrin. Production of this porphyrin by a mutant strain with impaired ability to form heme was unaffected by puromycin. Heme synthesis from glycine and succinate or from δ-aminolevulinate was decreased by limitation of methionine; it is suggested that coproporphyrin accumulation from glycine and succinate under conditions of methionine deficiency results from relief of feedback inhibition of δ-aminolevulinate synthase by heme. The development of δ-aminolevulinate synthase activity in response to low aeration is prevented by addition of δ-aminolevulinate. This repressive action of the latter is abolished when its conversion to heme is impeded by mutation or by methionine deficiency. It is suggested that heme, the quantitatively minor end product of the branched biosynthetic pathway, may regulate the flow of common intermediates when utilization of protoporphyrin by the magnesium branch is diminished. This regulation may be exerted by feedback inhibition of δ-aminolevulinate synthase and also by repression of enzyme formation.
Mutant Strains of
Rhodopseudomonas spheroides
Lacking δ-Aminolevulinate Synthase: Growth, Heme, and Bacteriochlorophyll Synthesis
Authors: Lascelles June , Altshuler Toby
Published: January 2020

Two mutant strains of
Rhodopseudomonas spheroides
were described which lacked δ-aminolevulinate synthase activity. They required δ-aminolevulinate for growth; they did not respond to protoporphyrin or magnesium photoporphyrin, and only poorly to hemin. Synthesis of cytochromes and heme by mutant H-4 was dependent upon δ-aminolevulinate; this strain did not form bacteriochlorophyll either with or without δ-aminolevulinate and, consequently, grew only under aerobic conditions. Mutant H-5 formed bacteriochlorophyll in response to δ-aminolevulinate and grew both anaerobically in the light and aerobically in the dark; the amount of δ-aminolevulinate needed for optimal anaerobic growth was higher than that required aerobically. Synthesis of bacteriochlorophyll and heme by suspensions of mutant H-5 incubated anaerobically in the light was dependent upon δ-aminolevulinate; bacteriochlorophyll production was completely inhibited by high aeration and by puromycin. The mutants differed in their ability to take up radioactive δ-aminolevulinate from the external environment; mutant H-5 was less active than mutant H-4 or the wild type. It was suggested that
R. spheroides
made only one form of δ-aminolevulinate synthase, which provided δ-aminolevulinate for bacteriochlorophyll and heme synthesis.
Effects of Antibiotics on Induction, Viability, and Reversion Potential of L-Forms of
Haemophilus influenzae
Authors: Lapinski E. M. , Flakas E. D.
Published: January 2020

L-form variants of
Haemophilus influenzae
were found to be more susceptible than their parent bacilli to streptomycin, kanamycin, tetracycline, erythromycin, and chloramphenicol if L-form inducer, penicillin, was present. This greater susceptibility was defined as the bactericidal effect for the variant forms of a concentration of antibiotic that is lower than but approximates the level bacteriostatic for the parents. In the absence of penicillin, reversion to and growth as bacilli occurred, although kanamycin, chloramphenicol, and erythromycin were lethal for round-body inocula on antibiotic reversion media in a few instances. The development of round bodies from bacillary inocula on induction medium was inhibited by bacteriostatic concentrations of chloramphenicol or tetracycline. The bacilli survived for 72 hr or more, whereas round bodies were dead within 24 hr.
Ultrastructural Changes in
Rhizopus stolonifer
Sporangiospores in Response to Anaerobiosis
Authors: Bussel J. , Buckley Patricia M. , Sommer N. F. , Kosuge T.
Published: January 2020

Rhizopus stolonifer
sporangiospores developed prominent ultrastructural changes under anoxia. Mitochondria were scattered randomly throughout the cytoplasm in spores incubated aerobically for 3 hr, but moved to the periphery of the cytoplasm when the spores were exposed to anoxia. Endoplasmic reticulum, inconspicuous in control spores, appeared near the plasmalemma and was frequently found connected to a nuclear membrane. The cytoplasm, otherwise usually uniformly dense and containing abundant ribosomes, appeared mottled under anoxia. The absence of ribosomes could account for the mottled appearance. Lipid inclusions were distinctively separated from the electron-transparent areas of the mottled cytoplasm. The increasing thickness of the inner wall indicated that the metabolic activity of spores continued under anoxia. When aerobic conditions succeeded anoxia, germ-tube protrusion occurred.
Effects of Oleate Starvation in a Fatty Acid Auxotroph of
Escherichia coli
K-12
Authors: Henning U. , Dennert G. , Rehn K. , Deppe Gisela
Published: January 2020

The effects of oleate starvation on an oleate auxotroph of
Escherichia coli
K-12 were investigated. Following removal of oleate from the mutant growing in a minimal glycerol-peptone medium, the cells stopped making deoxyribonucleic acid, ribonucleic acid, protein, and phospholipids; they began to die exponentially and finally lysed. During oleate starvation in minimal medium minus peptone, inhibition of macromolecular syntheses and death occurred; however, lysis did not follow. When growth ceased, no further dying was observed. It is shown that none of the early effects (inhibition of macromolecular syntheses and death) can be due to leakiness of the cells, induction of a prophage or a colicin, or lack of energy sources. The cause of inhibition of macromolecular syntheses remained unknown. Since the rate of death was the same as the generation time under different conditions, it appears that death is due to the defective synthesis of some cellular structure (quite possibly, cytoplasmic membrane) during phospholipid deficiency. Lysis was found to require protein synthesis; electron microscopy revealed a peculiar type of “lysis from within”; i.e., the shape of the cells did not change but fragmentation of the inner layer of the cell envelope occurred. The murein was found to be unaltered. Most likely, lysis was a consequence of the cell's attempt to synthesize cytoplasmic membrane with altered phospholipid composition or during phospholipid deficiency. Several membrane functions (respiration, adenosine triphosphate formation, permeability) existing before oleate removal were not lost during starvation. Therefore, general damage to the membrane did not occur, and it could be that most, if not all, described effects were due to defective de novo membrane synthesis.
Caulobacter crescentus
Mutants with Short Stalks
Authors: Schmidt Jean M.
Published: January 2020

Limitation of inorganic phosphate in the culture medium allows stalk elongation in wild-type
Caulobacter crescentus
. Mutants unable to form long stalks were isolated.
Production of Tubules and Bacteriophage-like Particles in Mycobacteria After Bacitracin Treatment
Authors: Rieber Manuel , Imaeda Tamotsu
Published: January 2020

Bacitracin-treated mycobacteria liberated tubules and phagelike particles which had no biological activity against selected species. These structures may reflect a state of defective lysogeny.
Crystalline Inclusions in
Bacillus thuringiensis
Authors: Norris J. R. , Proctor Heather M.
Published: January 2020

Crystalline inclusion bodies resembling those seen in
Clostridium cochlearium
were detected in cultures of
Bacillus thuringiensis
infected with bacteriophage.
Isolation of an Ornithine-containing Lipid from
Thiobacillus thiooxidans
Authors: Shively J. M. , Knoche H. W.
Published: January 2020

The ornithine-containing lipid was separated from the other lipids of
Thiobacillus thiooxidans
by thin-layer chromatography. The aminolipid possesses both amide and ester linkages.
Mapping of a Structural Gene for Valyl-Transfer Ribonucleic Acid Synthetase in
Escherichia coli
by Transduction
Authors: Tingle Marjorie A. , Neidhardt Frederick C.
Published: January 2020

A structural gene,
valS
, for the valyl-transfer ribonucleic acid synthetase of
Escherichia coli
has been mapped on the clockwise side of
pyrB
and is closely linked to it.
Nonrandom Mutagenesis of the
Escherichia coli
Genome by Nitrosoguanidine
Authors: Botstein D. , Jones E. W.
Published: January 2020

The distribution on the genetic map of mutations induced with nitrosoguanidine in stationary-phase cultures of
Escherichia coli
is nonrandom.
Germination of Single Bacterial Spores
Authors: Hashimoto Tadayo , Frieben W. R. , Conti S. F.
Published: January 2020

Changes in refractility and optical density occurring in individual spores of
Bacillus cereus
T and
B. megaterium
QM B1551 during germination were investigated by use of a Zeiss microscope photometer. The curves revealed that the germination process in single spores had two distinct phases; an initial rapid phase was followed by a second slower phase. Under the experimental condition employed, the first phase of germination of
B. cereus
spores lasted for approximately 75 ± 15 sec, whereas the second phase lasted for 3 to 4.5 min. In
B. megaterium
spores, the first phase was observed to last for approximately 2 min and the second phase for more than 7 min. The duration of the second phase was dependent on conditions employed for germination. The kinetics of the first phase were strikingly similar under all conditions of physiological germination. Time-lapse phase-contrast microscopy of germinating spores also revealed the biphasic nature of germination. It was postulated that the first phase represents changes induced by an initial partial hydration of the spore and release into the medium of dipicolinic acid, whereas the second phase reflects degradation of the cortex and hydration of the core.
Uptake of Glucose-
1
-
14
C
by
Pullularia pullulans
Authors: Merdinger Emanuel
Published: January 2020

Pullularia pullulans
cells were grown in a medium containing yeast extract, malt extract, glucose, and nutrient salts, in addition to glucose-
1
-
14
C
. The lipids extracted from the cells were fractionated by use of a single column packed with silicic acid. Of the total radioactive carbon added to the culture medium, the neutral lipid fractions contained 24.8%, whereas the phospholipid portions contained only 2.1%. The largest amount (16.5%) of
14
C among the neutral lipids was found in the fraction containing the free sterols. Among the phospholipids, the largest amount (1.1%) was found in phosphatidylserine and phosphatidylethanolamine. The second largest amount (9.6%) of the total
14
C used was found in trehalose, followed by carbon dioxide (7.3%).
Inhibition of Leukocyte Migration by a Staphylococcal Factor
Authors: Weksler Babette. B. , Hill M. J.
Published: January 2020

Cell wall mucopeptide isolated from virulent strains of
Staphylococcus aureus
has previously been found to potentiate subcutaneous staphylococcal lesions in mice. This cell wall fraction was found to inhibit the migration of polymorphonuclear leukocytes toward a chemotactic stimulus, as tested by the micropore filter chamber technique. A close correlation was shown to exist between in vivo “mouse virulence” of staphylococcal strains and the in vitro inhibition of leukocyte migration by the cell wall factor.
Serological Comparison of Ten GlycolyticMycoplasmaSpecies
Authors: Kenny George E.
Published: January 2020

Seventeen strains of mycoplasmata representing 11 named species were compared serologically by three parameters: growth inhibition on agar, double immunodiffusion, and complement fixation. In growth-inhibition studies, a strain labeledMycoplasma histotropicumwas found related to and perhaps best classified asM. pulmonis, a relationship confirmed by double immuno-diffusion studies. A comparison of the remaining 10 species demonstrated that two pairs of species could be shown to be closely related by complement fixation and double immunodiffusion but not by growth inhibition; these were:M. granularum-M. laidlawiiandM. felis-M. canis. M. pneumoniaeandM. gallisepticumwere the most serologically unique organisms in this study, showing very few cross-reactions with each other or other species. Overall, taxonomic groupings obtained by comparative serology appeared to correlate with the groupings obtained when the guanine plus cytosine contents of the deoxyribonucleic acid of mycoplasmata were employed as classification criteria. The group of organisms having a guanine plus cytosine content of 23 to 28% (M. canis, M. fermentans, M. hyorhinis, M. neurolyticum, andM. pulmonis) appeared to be generally serologically related. Thus the remarkable heterogeneity observed in the base composition of the deoxyribonucleic acid of orderMycoplasmatalesis also reflected and apparently paralleled by a corresponding serological heterogeneity.
Influence of Oxygen on Development of Nitrate Respiration in
Bacillus stearothermophilus
Authors: Downey R. J. , Kiszkiss D. F. , Nuner J. H.
Published: January 2020

A denitrifying mutant of
Bacillus stearothermophilus
NCA 2184, strain 2184-D, was used to explore the development of nitrate respiration in relation to oxygen respiration. Aerobically grown wild-type cultures could acquire the ability to use nitrate as a result of selection of nitrate-respiring mutants by the presence of nitrate and a reduced oxygen tension. Fluctuation analysis has revealed that the frequency of occurrence of the nitrate-respiring mutant is about 7.5 × 10
−8
per bacterium per generation. Nitrate reductase and nitrite reductase appeared to be induced sequentially in strain 2184-D by the addition of nitrate. The formation of both of these enzymes was repressed by oxygen so that cells grown aerobically with nitrate possessed a low basal level of nitrate reducatase and exhibited no denitrification. The rate of synthesis of nitrate reductase increased quickly after addition of nitrate and removal of oxygen. It then declined to a lower steady-state level. Cells grown anaerobically with nitrate retained approximately 30 to 40% of the respiratory activity of aerobically grown cells. Aeration of anaerobically grown cells in the presence of amino acids increased the respiratory activity to normal aerobic levels. This aeration promoted rapid degradation of the existing nitrate reductase with or without the added amino acids.
Unstable Binary Capsulated Transformants in Pneumococcus
Authors: Bernheimer Harriet P. , Wermundsen Ingbritt E.
Published: January 2020

Through transformation reactions, binary capsulated SI-III strains of pneumococci have been isolated that are unstable and lose the SI capsular genome at high frequency. The instability is caused by the specific mutation in the SIII capsular genome common to all of the unstable strains. In the family of strains studied, the SI capsular genome was integrated into the recipient chromosome in at least two loci: one apparently adjacent to the resident capsular genome and a second some distance from it. A hypothesis is presented to explain the instability of the strains on the basis of redundancy of genetic information.
Unique Protein Moieties for 30
S
and 50
S
Ribosomes of
Escherichia coli
Authors: Strnad Bruce C. , Sypherd Paul S.
Published: January 2020

Each major component of the proteins of 30
S
ribosomes from
Escherichia coli
was compared with the proteins of 50
S
ribosomes. The comparisons were done by using polyacrylamide gel electrophoresis in urea with differentially labeled proteins. The data show that no major protein is common to both ribosomes.
Regulation of Glyoxylate Metabolism in
Escherichia coli
K-12
Authors: Ornston L. N. , Ornston M. K.
Published: January 2020

The relative contributions of the dicarboxylic acid and the tricarboxylic acid cycles to the oxidative catabolism of glyoxylate in
Escherichia coli
K-12 were deduced by analysis of mutant strains that were blocked in the formation of glyoxylate carboligase and of malate synthase G (the “glycolate form” of malate synthase). Mutant strains unable to form malate synthase G were unimpaired in their ability to oxidize glyoxylate. Hence, the dicarboxylic acid cycle does not appear to play an essential role in this process. Organisms blocked in the synthesis of glyoxylate carboligase did not oxidize glyoxylate at a detectable rate, indicating that wild-type organisms convert glyoxylate to acetyl-coenzyme A and oxidize it via the tricarboxylic acid cycle. The foregoing evidence indicates that malate synthase G plays an anaplerotic role during growth with glycolate or acetate as the carbon source. The in vivo activity of malate synthase G was not detectable when the intracellular concentration of acetyl-coenzyme A was low, suggesting that this substrate or a closely related metabolite exerts a sensitive positive control over the enzyme. The synthesis of malate synthase G appears to be induced directly by glycolate which may be formed by a constitutive reduced nicotinamide adenine dinucleotide phosphate-dependent glyoxylate reductase in glyoxylate- or acetate-grown cells.
Biosynthesis of Riboflavine in
Corynebacterium
Species: the Purine Precursor
Authors: Baugh Charles M. , Krumdieck Carlos L.
Published: January 2020

Corynebacterium
species lacks the ability to convert either xanthine or guanine to adenine. This defect and the use of the purine nucleoside antibiotic decoyinine, which blocks the conversion of xanthosine monophosphate → guanosine monophosphate, permit an experimental design in which the interconversion of purines is largely prevented. Cultures of this organism were grown in the presence of decoyinine and various purine supplements. Data obtained by comparing the radioactivity incorporated from guanine-
2
-
14
C
or xanthine-
2
-
14
C
into bacterial guanine, xanthine, and riboflavine indicate that guanine or a close derivative of guanine is the purine precursor of riboflavine.
l
-Malate Oxidation by the Electron Transport Fraction of
Azotobacter vinelandii
Authors: Jurtshuk Peter , Bednarz A. J. , Zey Pinina , Denton C. H.
Published: January 2020

The membrane-bound
l
-malate oxidoreductase of
Azotobacter vinelandii
strain O was found to be a flavoprotein-dependent enzyme associated with the electron transport system (R
3
) of this organism. The particulate R
3
fraction, which possessed the
l
-malate oxidoreductase, carried out the cyanide-sensitive oxidation of
l
-malate,
d
-lactate, reduced nicotinamide adenine dinucleotide and nicotinamide adenine dinucleotide phosphate, succinate, cytochrome
c
, tetramethyl-
p
-phenylenediamine, and
p
-phenylenediamine, with molecular O
2
as the terminal electron acceptor.
d
-Malate was not oxidized, but
l
-malate was oxidized to oxalacetate. Phenazine methosulfate (PMS), vitamin K
3
, K
3
Fe(CN)
6
, nitro blue tetrazolium, and dichloroindophenol all served as good terminal electron acceptors for the
l
-malate oxidoreductase. Cytochrome
c
was a poor electron acceptor. Extensive studies on the
l
-malate oxidase and PMS and K
3
reductases revealed that all were stimulated specifically by flavine adenine dinucleotide and nonspecifically by di- or trivalent cations, i.e., Ca
++
, Ba
++
, Mn
++
, Mg
++
, Fe
+++
, Ni
++
, and Al
+++
. All these activities were markedly sensitive to ethylenediaminetetraacetate (EDTA). The
V
max
values for the
l
-malate oxidase, PMS, and vitamin K
3
reductases were, respectively, 3.4, 15.1, and 45.5 μmoles of substrate oxidized per min per mg of protein at 37 C. Spectral studies revealed that the
Azotobacter
R
3
flavoprotein and cytochromes (
a
2
,
a
1
,
b
1
,
c
4
, and
c
5
) were reduced by
l
-malate.
l
-Malate oxidase activity was sensitive to various inhibitors of the electron transport system, namely,
p
-chloromercuriphenylsulfonic acid, chlorpromazine, 2-
n
-heptyl-4-hydroxyquinoline-
N
-oxide, antimycin A, and KCN. Minor inhibitory effects were noted with the inhibitors 4,4,4-trifluoro-1-(2-thienyl)-1,3-butanedione, rotenone, and Amytal.
Response and Specificity of Antibodies forShigella flexneri: Demonstration of Type-specific Factors in Immunoglobulin G Fraction of Antiserum
Authors: Fukazawa Y. , Shinoda T. , Tsuchiya T.
Published: January 2020

Considerable amounts of immunoglobulin G (IgG) antibody appeared in hyperimmune rabbit serum at a late period during a course of immunization with several injections ofShigella flexneriO antigens. High yields of IgG antibody possessing homogenous specificity could be fractionated from crude gamma-globulin solution on a diethylaminoethyl-Sephadex column with 0.02mphosphate buffer (pH 6.6) containing 0.1mNaCl. Specificities of IgG antibodies for six serotypes ofS. flexneriwere demonstrated to be high as compared with those of whole sera and their IgM antibodies. Type-specific factors for antigens I to VI were shown in each IgG fraction according to serotype employed. Further, in most sera, subtype-specific factors could be detected in the IgG fraction. These results suggest that it would be desirable to use IgG antibodies for the typing ofS. flexneri.
Iron Transport in
Escherichia coli
: Relationship Between Chromium Sensitivity and High Iron Requirement in Mutants of
Escherichia coli
Authors: Wang Ching Chung , Newton Austin
Published: January 2020

Utilization of iron (Fe
3+
) by
Escherichia coli
depends upon a system which is determined by at least two genetic loci. Mutants which carry a deletion of the
tonB-trp
region of the chromosome grow only when very high concentrations of iron are present in the medium. These strains are sensitive to chromic ion (Cr
3+
) and, unlike the parent strain, fail to grow on MnSO
4
when FeSO
4
is not added to the medium. A second type of mutant, Chr2, which was isolated on the basis of its sensitivity to chromic ion, also requires a high concentration of iron for growth. This mutant can be distinguished phenotypically from the deletion mutants since it grows normally on low concentrations of iron, provided citrate is added to the medium. The chromium sensitivity of both types of mutants can be reversed by high concentrations of exogenous iron. The data are interpreted to indicate that the
E. coli
mutants studied are defective in iron transport and that residual iron transport is in some way inhibited by chromic ion.
Iron Transport in
Escherichia coli:
Roles of Energy-dependent Uptake and 2,3-Dihydroxybenzoylserine
Authors: Wang Ching Chung , Newton Austin
Published: January 2020

Escherichia coli
strains B/r and 2276 contain an active transport system for iron. The system is energy-dependent, repressed by excess iron in the growth medium, and capable of accumulating iron inside of the cells at concentrations 2,000-fold higher than those in the medium. Two
tonB-trp
deletion mutants, strains B/rlt and B/lt7, which are sensitive to chromic ion and require high levels of iron for normal growth, are deficient in this active transport system. A point mutant, strain Chr2, which is also sensitive to chromic ion and requires high levels of iron for growth, has the active uptake system but cannot synthesize a specific chelator for iron, 2,3-dihydroxybenzoylserine (DHBS). Evidence is presented to support the hypothesis that both the active uptake system and chelation of iron by DHBS play a role in iron uptake from iron-deficient medium. The chromium sensitivity of the mutants can be explained by inhibition of uptake of exogenous iron.
Glucose-6-Phosphate Dehydrogenase and Its Deficiency in Mutants of
Corynebacterium glutamicum
Authors: Ihnen Ernel D. , Demain Arnold L.
Published: January 2020

Corynebacterium glutamicum
is a member of a group of taxonomically related glutamate-excreting bacteria which utilize glucose both by the Embden-Meyerhof and the pentose phosphate pathways, the latter sequence accounting for 10 to 38% of the glucose metabolized. Some of the properties of glucose-6-phosphate dehydrogenase in crude extracts of
C. glutamicum
were studied. The enzyme was rapidly inactivated by dilution in tris (hydroxymethyl)aminomethane-hydrochloride buffer. This inactivation was prevented by the presence of 0.45
m
NaCl. Mg
++
was required for enzyme activity, but Mn
++
, Ca
++
, Sr
++
, and Ba
++
were equally effective. Growth of the organism under differing conditions did not markedly affect the specific activity of the enzyme. A generally applicable method for detecting colonies deficient in glucose-6-phosphate dehydrogenase was developed. Mutants so obtained were found to be auxotrophic for tryptophan. Upon reversion of the tryptophan requirement, the revertants still retained the property of glucose-6-phosphate dehydrogenase deficiency. Neither the mutants nor the revertants could grow as rapidly as the parent culture in glucose, in gluconate, or in a complex medium.
Arabinose-Leucine Deletion Mutants of
Escherichia coli
B/r
Authors: Kessler Donald P. , Englesberg Ellis
Published: January 2020

The control of
ara
gene expression was studied in mutants of
Escherichia coli
B/r containing deletions which fused the
l
-arabinose gene complex with the leucine operon (the normal gene order being
araDABIOC...leuDCBAO
). Complementation experiments with stable merodiploids showed that expression of
ara
genes
cis
to
araC-leu
deletions was controlled by the
trans
-acting product of the
araC
gene. Expression of
ara
genes
cis
to
araB-leu
deletions was under leucine control. These studies confirm the existence of a region between genes
araC
and
araB
essential for normal activator controlled expression of the
ara
structural genes. One deletion was characterized as an
araO-leu
deletion. Its effect on
ara
gene expression was unique in that
ara
genes were susceptible to potential regulation by both
l
-arabinose and leucine. These experiments suggest that two different species of messenger ribonucleic acid (mRNA) may be produced for the
ara-leu
region as a result of this deletion. One, under
l
-arabinose-activator control, is initiated in the
l
-arabinose region; the other, under leucine control, is initiated in the leucine region. The latter indicates that
araI
can be transcribed. Whether
araI
is transcribed in the former instance (mRNA made under activator control) remains to be established.
Significance of 12
S
Toxin of
Clostridium botulinum
Type E
Authors: Kitamura Masaru , Sakaguchi Sumiko , Sakaguchi Genji
Published: January 2020

The pathogenesis of type E botulism is discussed as an aspect of the physicochemical and biological properties of 12
S
toxins (prototoxin and trypsin-activated 12
S
toxin) and the Eα and Eβ components of each 12
S
toxin. A molecular weight of 350,000 was determined for each 12
S
toxin and 150,000 for Eα and Eβ. Owing to the structure comprising the subunits Eα and Eβ, 12
S
toxins are much more stable than Eα at low
p
H values and high temperatures. Such was also the case with type A 19
S
toxin and its α component. The Eα component alone accounts for the total toxicity of type E toxin. The toxic substance detected in the blood of the animals administered 12
S
toxins orally or parenterally was identified as Eα from the molecular size and the chromatographic pattern. Prototoxin escaping from detoxification in the stomach owing to the subunit structure may undergo dissociation in the intestine to release the Eα component. After absorption, the activated Eα appeared in the circulating blood without any further signs of dissociation or enzymatic digestion.
Synthesis of Deoxyribonucleic Acid After Ultraviolet Irradiation of Sensitive and Resistant
Haemophilus influenzae
Authors: Modak Sohan P. , Setlow Jane K.
Published: January 2020

Synthesis of deoxyribonucleic acid (DNA) has been measured as a function of ultraviolet (UV) radiation dose in wild-type and seven UV-sensitive strains of
Haemophilus influenzae
. At the UV doses used, all strains were able to resume DNA synthesis, even those which are unable to excise pyrimidine dimers from their DNA. These excisionless strains showed longer UV-induced delays in DNA synthesis than all but one of the other strains. The longest delay was shown by DB117, a strain which can excise dimers but which is recombination deficient and unable to rejoin X ray-induced single-strand breaks. All strains showed a progressive decrease in sensitivity as they approached the stationary phase.
Autolytic Enzyme System of
Streptococcus faecalis
V. Nature of the Autolysin-Cell Wall Complex and Its Relationship to Properties of the Autolytic Enzyme of
Streptococcus faecalis
Authors: Shockman Gerald D. , Cheney Margaret C.
Published: January 2020

Cell walls from exponential-phase cultures of
Streptococcus faecalis
ATCC 9790 contain an autolysin (a β-
N
-acetylmuramide glycanhydrolase, E.C. 3.2.1.17) which has been isolated from trypsin-speeded wall autolysates. The autolysin, which was excluded from Bio-Gel P-60, was further fractionated by diethylaminoethyl (DEAE)-cellulose chromatography or filtration on Bio-Gel P-200. After DEAE-cellulose chromatography, which removed most of the wall polysaccharide, autolysin activity was extremely labile and was rapidly lost at −20 C, even in the presence of albumin. The P-60-excluded enzyme was rapidly bound by walls at both 37 C (50% bound in about 1 min) and 0 C (50% bound in less than 4 min). Wall-bound autolysin could not be removed by 1.0
m
ammonium acetate (
p
H 6.9). Autolysin was also bound by walls that had been extracted with 10% trichloroacetic acid or treated with 0.01
n
periodate, suggesting that the nonpeptidoglycan wall polymers are not important for binding. Wall-bound autolysin was more stable than the soluble enzyme to proteinase digestion, acetone (40%), 8
m
urea (at 0 C), or to inactivation at 56 C. Two bacterial neutral proteinases (which do not hydrolyze ester bonds) activated latent wall-bound autolysin, suggesting that activation results from the cleavage of one or more peptide bonds. The group A streptococcal proteinase activated latent autolysin but differed from the other proteinases in that it did not inactivate soluble autolysin. The results suggest that the autolysin is not covalently linked to the wall. The high affinity of the walls for the autolysin appears to be responsible for the firm, not easily reversed binding.
Physical Heterogeneity Among
Bacillus subtilis
Deoxyribonucleic Acid Molecules Carrying Particular Genetic Markers
Authors: Stewart Charles R.
Published: January 2020

In a
Bacillus subtilis
deoxyribonucleic acid (DNA) preparation, extracted and purified by the Marmur procedure, the DNA molecules carrying a particular marker are heterogeneous with respect to molecular weight, buoyant density, and thermal stability. This finding constitutes evidence against unique points of breakage during DNA isolation. The variation in buoyant density suggests a local compositional heterogeneity in the chromosomal region of certain markers. The variation in molecular weight provides an explanation for the results of certain transformation experiments that are otherwise poorly understood. An example of such a result is the observation that acridine orange increases the efficiency of differential thermal inactivation of markers. An explanation of this phenomenon is suggested by the demonstration that acridine orange can decrease the natural intramarker heterogeneity in melting behavior.
Kinetics of Induction and Purification of Chloramphenicol Acetyltransferase from Chloramphenicol-resistant
Staphylococcus aureus
Authors: Winshell E. , Shaw W. V.
Published: January 2020

Plasmid-mediated chloramphenicol resistance in
Staphylococcus aureus
has been shown to involve acetylation of chloramphenicol by an enzyme induced by growth in the presence of the antibiotic and certain analogues. Analysis of the kinetics of induction has been complicated by (i) the intrinsic inhibitory effects of chloramphenicol on induced enzyme synthesis and (ii) the rapid disappearance of inducer after synthesis of the acetylating enzyme. The compound related to
d
-threo chloramphenicol which lacks a C
3
hydroxyl substituent (3-deoxychloramphenicol) is a potent inducer of chloramphenicol acetyltransferase but is ineffective as an antibiotic and is not a substrate for the enzyme. The availability of such a “gratuitous” inducer has simplified an analysis of the kinetics of induction of chloramphenicol acetyltransferase. The enzyme from induced bacteria has been purified to homogeneity and has been compared with the analogous enzyme present in
E. coli
which harbors a resistance transfer factor with the chloramphenicol resistance determinant.
Mutation in
Escherichia coli
K-12 Mediating Spherelike Envelopes and Changed Tolerance to Ultraviolet Irradiation and Some Antibiotics
Authors: Normark Staffan
Published: January 2020

In a mutation experiment with a rough, ampicillin-resistant strain of
Escherichia coli
K-12, two smooth ampicillin-sensitive mutants were isolated. One of the mutants (with the
envA
gene) was recently described. The second mutant (strain D23) with the
envB
gene which has been mapped to a position close to streptomycin resistance (
strA
) at 64 min is described. The
envB
gene gives rise to spherelike cells. Electron microscopy revealed an abnormal septum formation and a circular distribution of the nuclear material. Strain D23 (with
envB
) showed a changed resistance to several antibiotics as well as an increased tolerance to ultraviolet irradiation. The
envB
gene decreased the ampicillin resistance mediated by the
ampA
gene (at 82 min), but no effect was found on episomally mediated penicillin resistance.
Methylammonium Resistance in
Aspergillus nidulans
Authors: Arst H. N. , Cove D. J.
Published: January 2020

Mutants of
Aspergillus nidulans
resistant to methylammonium toxicity are simultaneously derepressed in the presence of ammonium for apparently all ammonium-repressible activities. Enzyme assays directly demonstrate derepression of nitrate, nitrite, and hydroxylamine reductases, xanthine dehydrogenase, urate oxidase, and allantoinase, whereas in vivo tests show that ammonium and methylammonium repression or inhibition (or both) is relieved in these mutants in pathways of nitrate assimilation, purine transport and degradation, and amino acid, amine, and amide catabolism. Ammonium and methylammonium uptake is apparently not defective in these mutants, for they grow normally on limiting levels of these ions as sole nitrogen source. There is no evidence that more than one gene can mutate to produce the methylammonium resistance (
mea
R
) phenotype. Such mutations are semidominant in both heterocaryons and diploids. The ability of
mea
R
mutations to effect derepression of activities specified by genes within another nucleus in a heterocaryon shows that the action of the
mea
product is not restricted to the nucleus. Three types of hypotheses might explain this generalized derepression. First, ammonium and methylammonium might not themselves be co-repressors but might require a metabolic conversion, blocked in these mutants, to become co-repressors. Secondly, the
mea
locus might specify an activity expressed in
mea
R
but not wild-type (
mea
S
) strains, which diminishes the concentration of ammonium and methylammonium participating in co-repression. Finally, ammonium repression might involve a macromolecular control element specified by the
mea
R
locus and common to many or all ammonium-repressible systems. The existence of “regulation reversal mutations” at the
mea
R
locus and the lack of uniformity and coordination with which different enzymatic activities respond to mutational derepression is most compatible with the last type of hypothesis.