bluuebunny/crossref_metadata_2025 huggingface dataset:
Cell Division of
Escherichia coli
: Control by Membrane Organization
Authors: Wu Po C. , Pardee Arthur B.
Published: January 2020

Cells of certain strains of
Escherichia coli
, after transfer from 37 to 45 C and incubation for 16 min, were observed to swell and subsequently divide synchronously. This swelling and the resulting stretching of the membrane are proposed to be the basis for the synchronous division. Four lines of evidence support this hypothesis. First, osmotic protection by the addition of either sodium chloride or sucrose at the time of heat shock prevents both swelling and synchrony. Second, a mutant neither swelled nor divided synchronously after heat shock. Third, cells grown for several generations with 10% sucrose in the medium swelled and divided synchronously upon transfer to medium without sucrose. Fourth, the mutant not synchronized by heat shock also swelled and underwent synchronous division after the osmotic shift. A tentative model is suggested for the normal control of division, based on membrane configuration at the septation site.
Effect of Methionine Sulfoximine and Methionine Sulfone on Glutamate Synthesis in
Klebsiella aerogenes
Authors: Brenchley Jean E.
Published: January 2020

At least two pathways exist in
Klebsiella aerogenes
for glutamate synthesis. A mutant blocked in one pathway due to the loss of glutamate dehydrogenase (
gltD
) does not require glutamate and has the same growth characteristics as the parent strain in most media; however, its growth is inhibited by the analogues methionine sulfoximine and methionine sulfone. Wild-type
Klebsiella
is resistant to 0.1 M methionine sulfoximine or methionine sulfone, whereas the
gltD
mutant is sensitive to 1 mM concentrations. Either glutamate or glutamine is effective in overcoming this inhibition. Activities of both glutamine synthetase and glutamate synthetase, two enzymes involved in the second pathway of glutamate synthesis, are inhibited by methionine sulfoximine and methionine sulfone. The primary effect of methionine sulfoximine appears to be the prevention of glutamine production necessary for subsequent glutamate synthesis via glutamate synthetase enzyme.
Role of Reduced Exogenous Organic Compounds in the Physiology of the Blue-Green Bacteria (Algae): Photoheterotrophic Growth of a “Heterotrophic” Blue-Green Bacterium
Authors: Ingram L. O. , Calder J. A. , Van Baalen C. , Plucker F. E. , Parker P. L.
Published: January 2020

Nostoc
sp. (strain Mac) was shown to be capable of using glucose, fructose, or sucrose as a sole source of carbon and energy in the dark. In the light in the absence of exogenously supplied CO
2
, this strain exhibited a more versatile metabolism. In addition to the three sugars above, glycerol and acetate served as sole sources of carbon. This photoheterotrophic growth in the absence of exogenously supplied CO
2
appears to involve O
2
-evolving photosynthesis. The action spectrum for photoheterotrophic growth on acetate closely resembles the action spectrum for photosynthesis. The physiology of photoheterotrophic growth was further investigated through determinations of stable carbon isotope ratios and measurements of gas exchanges. These investigations suggest that respired CO
2
from substrate oxidation is assimilated by the photosynthetic machinery.
Sodium and Other Inorganic Growth Requirements of
Bacteroides amylophilus
Authors: Caldwell Daniel R. , Keeney Mark , Barton Justice S. , Kelley Juanita F.
Published: January 2020

Bacteroides amylophilus
has growth requirements for Na
+
, PO
4
3−
, K
+
, and small quantities of Mg
2+
. No requirement could be shown for Ca
2+
in media previously found growth-yield-limiting for
Bacteroides succinogenes
. Deletion of Co
2+
, Mn
2+
, Cl
−
, or SO
4
2−
did not affect growth. Quantitative studies indicate that Na
+
, K
+
, and PO
4
3−
have differing effects on the growth of
B. amylophilus
. A concentration of sodium and potassium ions affects both growth rate and growth yield, whereas a phosphate concentration markedly affects growth yield, but affects growth rate only slightly, if at all. The sodium requirement of
B. amylophilus
is absolute. It cannot be replaced by K
+
, Li
+
, Rb
+
, or Cs
+
. The latter three monovalent cations are toxic to
B. amylophilus
if supplied to the organism at Na
+
-replacing concentrations. K
+
is inactive at similar concentrations. The K
+
requirement of
B. amylophilus
may be satisfied by Rb
+
. The concentration of Na
+
required by
B. amylophilus
for abundant growth suggests that
B. amylophilus
should be considered a slightly halophilic organism. The results suggest that Na
+
may be a more frequent requirement among terrestial bacteria obtained from relatively low-salt environments than has been previously believed.
Glutamic Acid Decarboxylase in Spores ofBacillus megateriumand Its Possible Involvement in Spore Germination
Authors: Foerster Charlene Wehe , Foerster Harold F.
Published: January 2020

Spores ofBacillus megateriumwere examined for glutamic acid decarboxylase (GAD). Although dormant spores showed no GAD activity, spores given sonic treatment and heat-activated spores had high activities when assayed for this enzyme. Several parameters of GAD in heat-activated spores were examined. The effects of KCN, NaN3, 2,4-dinitrophenol, and KF on GAD activity were examined. Only KCN was an effective inhibitor of GAD activity in heated spores and was also shown to be the only effective inhibitor of GAD activity in vegetative bacteria. Similar patterns of inhibition were obtained with GAD activity and with spore germination, KCN being the only effective inhibitor of both, although at different concentrations. Spore GAD activity in heat-activated spores showed a loss with storage at 4 C; on the other hand, storage at 25 C was not accompanied by a loss, but, to the contrary, showed an increase in GAD activity of about 30%. A comparison of GAD activity at different times during germination, growth, and sporulation showed it to be highest in freshly germinated spores. Although vegetative cells contained GAD activity, the level in log-phase cells was approximately one-half the level obtained with freshly germinated spores. Heat-activated mutant spores with a requirement of γ-aminobutyric acid for germination gave no GAD activity. GAD activity appeared in mutant spores after germination and increased to levels comparable to parent spores after 9 min of germination.
Replication of Deoxyribonucleic Acid During the Division Cycle of
Salmonella typhimurium
Authors: Cooper Stephen , Ruettinger Therese
Published: January 2020

The rate of thymidine incorporation into cells of
Salmonella typhimurium
growing in different media has been measured. In glucose-minimal medium, deoxyribonucleic acid (DNA) replication occurs during the first two-thirds of the division cycle; the final one-third of the division cycle was devoid of DNA replication. The measured doubling time of
S. typhimurium
in this medium is approximately 48 min, indicating that C (the time for a round of replication) and D (the time between termination and cell division) are approximately 32 and 16 min, respectively. At slower growth rates the pattern of replication is the same as glucose minimal medium. At faster growth rates the “gap” in DNA synthesis disappears. At rapid growth rates evidence for multiple forks is obtained.
Effect of Iron and Salt on Prodigiosin Synthesis inSerratia marcescens
Authors: Silverman Melvin P. , Munoz Elaine F.
Published: January 2020

Serratia marcescenswild-types ATCC 264 and Nima grew but did not synthesize prodigiosin in a glycerol-alanine medium containing 10 ng of Fe per ml. Wild-type 264 required the addition of 0.2 μg of Fe per ml for maximal growth and prodigiosin synthesis; Nima required 0.5 μg of Fe per ml. Three percent, but not 0.1%, sea salts inhibited prodigiosin synthesis in a complex medium containing up to 10 μg of Fe per ml. NaCl was the inhibitory sea salt component. The inhibition was not specific for NaCl; equimolar concentrations of Na2SO4, KCl, and K2SO4also inhibited prodigiosin synthesis. Experiments with strains 264 and Nima and with mutant WF which cannot synthesize 4-methoxy-2-2′-bipyrrole-5-carboxyaldehyde (MBC), the bipyrrole moiety of prodigiosin, and with mutant 9-3-3 which cannot synthesize the monopyrrole moiety 2-methyl-3-amylpyrrole (MAP) showed that both MBC synthesis and the reaction condensing MAP and MBC to form prodigiosin were relatively more sensitive to NaCl inhibition than the MAP-synthesizing step. The capacity of whole cells to condense MAP and MBC was present, but inactive, in cells grown in NaCl; removal of the NaCl from non-proliferating salt-grown cells restored the activity. Other evidence suggests the existence of a common precursor to the MAP- and MBC-synthesizing pathways.
Benzoate Metabolism in
Pseudomonas putida
(
arvilla
) mt-2: Demonstration of Two Benzoate Pathways
Authors: Nakazawa Teruko , Yokota Takeshi
Published: January 2020

Benzoate-grown cells of
Pseudomonas putida
(
arvilla
) mt-2 contain both metapyrocatechase and pyrocatechase activities, although the former activity is much higher than that of the latter. A spontaneous mutant deficient in metapyrocatechase and 2-hydroxymuconic semialdehyde hydrolyase, the first two enzymes in the
meta
-cleavage pathway of the ring of catechol, has been isolated from this strain. This mutant grows well on a minimal medium containing benzoate as a sole carbon source and has the high activity of pyrocatechase. These findings indicate that the strain mt-2 possesses the genetic capacity for enzymes of both the
meta
- and
ortho
-cleavage pathways of benzoate degradation, but its phenotypic expression is the
meta
pathway.
Purification of
Synechococcus lividus
by Equilibrium Centrifugation and Its Synchronization by Differential Centrifugation
Authors: Sitz Thomas O. , Schmidt Robert R.
Published: January 2020

A culture of the thermophilic, unicellular, blue-green alga
Synechococcus lividus
was freed from two thermophilic bacteria by use of equilibrium (isopycnic) centrifugation in Ficoll density gradients. After removal of the bacteria, the alga would grow only on agar plates in a high carbon dioxide atmosphere. Intermittent illumination, equilibrium centrifugation, and differential centrifugation were tested as techniques for obtaining synchronized cultures of the alga. Daughter cells selected by differential centrifugation in Ficoll density gradients yielded the best synchrony, and a cross-wall index of 85% was observed during the period of cell division.
Characterization and Genetic Analysis of a Mutant of
Escherichia coli
K-12 with Rounded Morphology
Authors: Matsuzawa Hiroshi , Hayakawa Kou , Sato Tetsuji , Imahori Kazutomo
Published: January 2020

A morphological mutant of
Escherichia coli
K-12 that grows as round cells at 30, 37, or 42 C in a variety of complex and synthetic media has been isolated and characterized. The gene concerned, designated
rodA
, has been shown to be on the chromosome between the
purE
and
pyrC
loci and to be located at about minute 15. The
rodA
gene has been found to be co-transducible with the
lip
gene at a frequency of 95%. The
rodA
mutant showed an increased resistance to ultraviolet irradiation and a changed sensitivity to drugs. The resistance to ultraviolet irradiation and mitomycin C appears to be co-transducible with the
rodA
gene.
Repression of In Vivo Synthesis of the Mitochondrial Elongation Factors T and G in
Saccharomyces fragilis
Authors: Richter D.
Published: January 2020

In vivo synthesis of the mitochondrial elongation factors T and G in the yeast
Saccharomyces fragilis
can be repressed. Enzymatic activity assays and immunochemical titration methods reveal that cells grown in the presence of 8% glucose or in the absence of oxygen contain relatively lower amounts of mitochondrial elongation factors than cells grown in the presence of lactate. In contrast, in vivo production of the cytoplasmic elongation factors 1 and 2 does not respond to such a change of extracellular conditions. The rate of growth does not affect the level of the mitochondrial elongation factors. Production of both enzymes is almost constant during logarithmic growth, but decreases when the stationary phase is reached. Chloramphenicol, an inhibitor of mitochondrial protein synthesis, does not block but, rather, seems to enhance the in vivo synthesis of mitochondrial T or G.
Autolytic Activity and Its Association with the Development of Competence in Group H Streptococci
Authors: Ranhand Jon M.
Published: January 2020

Seventeen strains of group H streptococci were tested for their ability to develop competence for genetic transformation, either spontaneously or with the addition of competence factor derived from strain Challis supernatant fluids, and for their ability to autolyze. Autolysis was measured as a decline in optical density after washed cells were placed in a buffer at pH 9. Kinetic experiments showed that, in strains Challis, SBE I/II, WE4, SR 30, and a strain (FW 227) cured of its bacteriophage, competence and the ability to autolyze occurred simultaneously. Since autolysis was observed only in (i) competent cells, (ii) cells that passed their peak of competence, and (iii) those cells that exhibit a potential for developing competence but never go on to transform (i.e., lysogenized Challis cells), it is concluded that, in the group H streptococci, autolytic events are associated with the competent state. Strains that transformed but did not autolyze were not found.
Transduction of Rifampin Resistance in Group A Streptococci
Authors: Stuart James G. , Ferretti Joseph J.
Published: January 2020

Rifampin-resistant strains of group A streptococci were isolated as spontaneous mutants. Transduction analyses employing phage A25 showed the rifampin marker to be transferred with high frequency. The mutations conferring resistance to rifampin and streptomycin are not co-transducible.
Lysis of
Saccharomyces cerevisiae
with 2-Deoxy-2-Fluoro-
d
-Glucose, an Inhibitor of the Cell Wall Glucan Synthesis
Authors: Biely P. , Kovarik J. , Bauer S.
Published: January 2020

The effect of a synthetic glucose analogue, 2-deoxy-2-fluoro-
d
-glucose (FG) on growth and glucose metabolism of
Saccharomyces cerevisiae
was studied. The addition of FG (0.005-0.05%) to a 2% glucose medium resulted in reduction of the initial growth rate and, after several hours, in a complete cessation of the culture growth. These two events were due to extensive lysis of the population which continued long after the period when no more growth was recorded. Electron microscope examination of lysed cells showed that the lysis was a consequence of a dissolution of the cell walls. FG inhibited to a similar extent the initial growth rate and the incorporation of radioactivity from labeled glucose into growing population. The inhibition of radioactivity incorporation from glucose by growing protoplasts was much less. The yeast was found to be extremely FG sensitive whenever the synthesis of new cell wall material was involved. All observations imply that FG interferes mainly with the cell wall formation of
S. cerevisiae
. A comparison of the FG effects on metabolic activity of protoplasts, simultaneous secretion of mannan-proteins into the growth medium, and the formation of glucan fibrils on the surface of protoplasts demonstrated that the cell wall glucan synthesis is the most FG-sensitive process and evidently the growth-limiting factor in intact cells. FG-resistant cells were selected during growth experiments. They exhibited an altered mode of cell division when grown in the presence of FG.
Tyrosine and Phenylalanine Biosynthesis in
Escherichia coli
K-12: Complementation Between Different
tyrR
Alleles
Authors: Im S. W. K. , Pittard J.
Published: January 2020

Dominance tests in diploids have confirmed that the product of the
tyrR
gene is involved in a negative control system affecting the synthesis of both 3-deoxy-
d
-arabinoheptulosonic acid 7-phosphate (DAHP) synthetase (tyr) and DAHP synthetase (phe). Some
tyrR
mutants are derepressed for the synthesis of both DAHP synthetase (tyr) and (phe), whereas others are derepressed for the synthesis of DAHP synthetase (tyr) but overrepressed for the synthesis of DAHP synthetase (phe). Complementation tests between these alleles confirm that they are in the same cistron. The allele causing overrepression of enzyme synthesis is dominant over both the wild type and the derepressing allele in diploids.
Initiation of Deoxyribonucleic Acid Replication in a Temperature-Sensitive Mutant of
B. subtilis
: Evidence for a Transcriptional Step
Authors: Laurent Simone J.
Published: January 2020

A mutant of
Bacillus subtilis
unable to initiate a new round of replication at 45 C has been described. Here we show that inhibition of DNA synthesis in this mutant is reversible and that DNA synthesis is resumed at low temperature, even in the presence of chloramphenicol. Initiation of a new replication cycle thus can occur in the absence of protein synthesis. A thermolabile component required for initiation therefore appears to be synthesized at 45 C in an inactive form and can be activated at 30 C in the presence of an inhibitor of protein synthesis. Although resistant to chloramphenicol, the reinitiation of replication occurring after lowering the temperature is sensitive to rifampin and streptolydigin.
Turnover of Phosphatidylglycerol in
Escherichia coli
Authors: Ballesta J. P. G. , Garcia Carmen L. de , Schaechter M.
Published: January 2020

In growing cultures of
Escherichia coli
, the nonacylated glycerol of phosphatidylglycerol (PG) is labeled more rapidly than is the acylated glycerol. This is, in part, due to a rapid exchange reaction of the nonacylated glycerol. Only some of the PG molecules undergo this reaction while others are stable. Using a mutant unable to make glycerophosphate, we have shown that the nonacylated glycerol of PG can exchange with non-phosphorylated glycerol.
Two Malic Enzymes in
Pseudomonas aeruginosa
Authors: Eyzaguirre J. , Cornwell E. , Borie G. , Ramírez B.
Published: January 2020

Cell-free extract supernatant fluids of
Pseudomonas aeruginosa
were shown to lack malic dehydrogenase but possess a nicotinamide adenine dinucleotide (NAD)- or NAD phosphate (NADP)-dependent enzymatic activity, with properties suggesting a malic enzyme (malate + NAD (NADP) → pyruvate + reduced NAD (NADH) (reduced NADP [NADPH] + CO
2
), in agreement with earlier findings. This was confirmed by determining the nature and stoichiometry of the reaction products. Differences in heat stability and partial purification of these activities demonstrated the existence of two malic enzymes, one specific for NAD and the other for NADP. Both enzymes require bivalent metal cations for activity, Mn
2+
being more effective than Mg
2+
. The NADP-dependent enzyme is activated by K
+
and low concentrations of NH
4
+
. Both reactions are reversible, as shown by incubation with pyruvate, CO
2
, NADH, or NADPH and Mn
2+
. The molecular weights of the enzymes were estimated by gel filtration (270,000 for the NAD enzyme and 68,000 for the NADP enzyme) and by sucrose density gradient centrifugation (about 200,000 and 90,000, respectively).
Genetics and Biochemistry of Pyrimidine Biosynthesis in
Bacillus subtilis
: Linkage Between Mutations Resulting in a Requirement for Uracil
Authors: Kelleher Raymond J. , Gooder Harry
Published: January 2020

A number of independently derived uracil-requiring mutant strains of the parent strain 168 were mapped by inter-mutant transformation crosses. Only a few of these mutant strains were found to be transformable. Studies were performed in which these transformable uracil-requiring mutant strains were used as the recipient of deoxyribonucleic acid extracted from phenotypically similar mutant strains. The results yielded data resulting in a fine-structure map in which all mutations were found to be linked in a small region corresponding to that previously published as the uracil region of the
Bacillus subtilis
genome.
Genetic Characterization of Mutations Which Affect Catabolite-Sensitive Operons in
Escherichia coli
, Including Deletions of the Gene for Adenyl Cyclase
Authors: Brickman Edith , Soll Larry , Beckwith Jon
Published: January 2020

Sixty-two spontaneous mutations have been characterized which reduce the level of expression of catabolite-sensitive operons. These mutations appear to affect either the
crp
(catabolite gene activator protein) or
cya
(adenyl cyclase) loci. No new loci have been discovered. Deletions of the
cya
gene do not remove an essential function. φ80 transducing phage for the
cya
gene have been used to do recombination and complementation studies on
cya
mutants.
Metabolic Regulation by Homoserine in
Escherichia coli
B/r
Authors: Kotre Ann M. , Sullivan Stephen J. , Savageau Michael A.
Published: January 2020

A mathematical analysis of branched pathway regulation has led to the prediction of a novel homoserine control in
Escherichia coli
B. Experimental support for such control is presented in this paper. Homoserine, the precursor of both threonine and methionine, inhibits nicotinamide adenine dinucleotide phosphate (NADP
+
)-specific glutamate dehydrogenase (EC 1.4.1.4), the enzyme catalyzing the first reaction in ammonia assimilation. Physiological and biochemical evidence for this effect are offered. Homoserine depresses the growth rate of the organism, and glutamate, the product of the inhibited reaction, reverses this effect. The NADP
+
-specific glutamate dehydrogenase activity in cell-free extracts is inhibited by homoserine, and this inhibition parallels the restriction of growth rate. These effects are found in other enteric bacteria which share a similar overall pattern of control for the amino acids derived from aspartate. On the other hand, a sampling of more distantly related species which have different pathways and/or regulatory patterns provides no evidence for homoserine inhibition of the glutamate dehydrogenase reaction.
Molecular and Genetic Studies of an R Factor System Consisting of Independent Transfer and Drug Resistance Plasmids
Authors: Van Embden Jan , Cohen Stanley N.
Published: January 2020

Certain genetic, structural, and biochemical properties of a class 2 R-factor system consisting of the conjugally proficient transfer plasmid I and the naturally occurring non-conjugative tetracycline (Tc) resistance plasmid 219 are reported. I and 219 exist as separate plasmid deoxyribonucleic acid (DNA) species in both
Escherichia coli
and
Salmonella panama
, having molecular weights of 42 × 10
6
and 5.8 × 10
6
, respectively. The buoyant densities of I and 219 are 1.702 and 1.710 g/cm
3
, respectively, in neutral cesium chloride. Although the Tc resistance plasmid is not transmissible in a normal conjugal mating, it is mobilized in a three-component mating by plasmid I and by certain other conjugative plasmids of the fi
+
or fi
−
phenotype. Mobilization does not appear to involve intermolecular recombination between plasmids, and no covalent linkage of resistance markers and fertility functions is observed. Transformation of CaCl
2
-treated
E. coli
by plasmid DNA is shown to be a useful procedure for studying the biological properties of different plasmid molecular species that have been fractionated in vitro, and for selectively inserting non-self-transmissible plasmids into specific bacterial strains. The effects of tetracycline on the rate of protein synthesis carried out by plasmid 219 were studied by using isolated
E. coli
minicells into which this plasmid had segregated. Consistent with the results of earlier investigations showing the inducibility of plasmid-mediated Tc resistance in
E. coli
, the antibiotic was observed to stimulate protein synthesis in minicells carrying the plasmid 219 and totally inhibit
3
H-leucine incorporation by minicells lacking the Tc resistance marker. Five discrete polypeptide species were synthesized by minicells carrying plasmid 219; exposure of minicells or parent bacteria to Tc resulted in specific and reproducible changes in polypeptide synthesis patterns.
Modification of Ribosomes in Cryptopleurine-Resistant Mutants of Yeast
Authors: Skogerson Lawrence , McLaughlin Calvin , Wakatama Eunice
Published: January 2020

Cryptopleurine-resistant mutants of
Saccharomyces cerevisiae
were isolated. A single, recessive nuclear gene, very closely linked to the mating locus (2.1 centimorgans), is responsible for resistance. Ribosomes from the mutants were found to be resistant to cryptopleurine when analyzed by poly(U)-directed polyphenylalanine synthesis. Analysis of the distribution of ribosomes between monosomes and polysomes in sensitive cells exposed to cryptopleurine suggests that some step is inhibited during the elongation phase of protein synthesis.
Suppression of
lex
Mutations Affecting Deoxyribonucleic Acid Repair in
Escherichia coli
K-12 by Closely Linked Thermosensitive Mutations
Authors: Mount David W. , Walker Anita C. , Kosel C.
Published: January 2020

A major class of ultraviolet (UV)-resistant derivatives of
lex
−
strains of
Escherichia coli
K-12 grows normally at 30 C but at 42.5 C fails to produce colonies on complete or minimal agar. At 42.5 C these thermosensitive strains form filaments without septa, due to an apparent defect in cell division. Deoxyribonucleic acid degradation in UV-irradiated cultures of the thermosensitive strains is slow, in contrast to the rapid degradation in UV-irradiated cultures of the parental
lex
−
strains. The thermosensitive mutations (
tsl
) are tightly linked (less than 0.04 min on the
E. coli
K-12 linkage map) to the site of the
lex
mutation in the parental strain and could lie within the same gene. The
tsl
+
/
tsl
−
heterozygotes grow at 42.5 C and are UV resistant when grown at 30 or 42.5 C. The
tsl
mutations are, therefore, recessive in contrast to
lex
mutations, which are dominant. It appears likely that the
tsl
mutations alter the diffusible product that gives rise to the Lex
−
mutant phenotype. This product appears to be necessary for deoxyribonucleic acid repair and cell division.
Biosynthetic Precursors of Vitamin K as Growth Promoters for
Bacteroides melaninogenicus
Authors: Robins D. J. , Yee R. B. , Bentley Ronald
Published: January 2020

The growth of a vitamin K-requiring strain of
Bacteroides melaninogenicus
was promoted by some postulated and proven biosynthetic precursors of bacterial menaquinones, 1,4-dihydroxy-2-naphthoic acid, shikimic acid, chorismic acid, and 4(2′-carboxyphenyl)-4-oxobutyric acid. Growth of the organism with [
2
′,
4
-
14
C
2
]-4(2′-carboxy phenyl)-4-oxobutyric acid as the vitamin K replacement gave rise to a mixture of radioactive menaquinone-9 and menaquinone-10; the dilution factor for this incorporation was 1.8.
Restoration of Active Transport in an Mg
2+
-Adenosine Triphosphatase-Deficient Mutant of
Escherichia coli
Authors: Rosen Barry P.
Published: January 2020

A neomycin-resistant mutant of
Escherichia coli
, NR70, lacking membrane-bound Mg
2+
-adenosine triphosphatase (EC 3.6.1.3) activity has been isolated. Both whole cells and membrane vesicles exhibit a reduced ability to accumulate amino acids and sugars. Other membrane-related functions such as oxygen consumption, the in vivo hydrolysis of
o
-nitrophenyl-β-
d
-galactoside, and the phosphoenolpyruvate-dependent phosphotransferase system did not exhibit reduced activities in NR70. Amino acid transport could be partially restored by the addition of
N,N
′-dicyclohexylcarbodiimide. The results suggest that a role of the Mg
2+
-adenosine triphosphatase may be to participate in the coupling of energy derived from the electron transport chain to other processes such as transport.
Growth Cycle of Predacious Bdellovibrios in a Host-Free Extract System and Some Properties of the Host Extract
Authors: Horowitz Aviva T. , Kessel M. , Shilo M.
Published: January 2020

Host-free growth and reproduction of a host-dependent strain of
Bdellovibrio bacteriovorus
incubated with an extract from host cells were studied. The morphological changes occurring in the cells were correlated with deoxyribonucleic acid (DNA) synthesis as measured by labeled nucleotide or orthophosphate incorporation. The host-free developmental cycle of
Bdellovibrio
is similar to that of the two-membered system; the early loss of flagella, the elongation into filaments, and multiple fission into flagellated progeny are typical for both host-free and intraperiplasmic development of bdellovibrios. Filament length and time of division appear to depend on the concentration of the host extract. Host extract was found to be heat stable and DNase stable, and Pronase sensitive and RNase sensitive. Addition of ribonucleic acid to the extract medium at various times during the
Bdellovibrio
growth cycle demonstrated that host extract is required continuously during the cycle for growth. The observations reported give a unified picture of
Bdellovibrio
development and allow for the suggestion that wild-type bdellovibrios depend upon the presence of some host factor for induction of DNA synthesis, whereas depletion of host factor triggers division. The ecological implications of such host dependence are discussed.
Three Different Missense Suppressor Mutations Affecting the tRNA
GGG
Gly
Species of
Escherichia coli
Authors: Hill C. W. , Combriato Gabriele , Dolph William
Published: January 2020

The
Escherichia coli
suppressor mutation,
supT
, has been shown to cause a C → U substitution in the middle position of the tRNA
GGG
Gly
anticodon. This is the same tRNA species that is altered by the
glyUsu
AGA
mutation studied previously. This finding indicates that the
supT
mutant tRNA reads the glutamic acid codon, GAG. The
supT
suppressor has also been converted to a new suppressor, called
glyUsu
GAA
, which will suppress the GAA mutation,
trpA46
. The in vivo suppression efficiencies of each of these three missense suppressors has been measured and are as follows:
glyUsu
AGA
, 3.6%;
supT
, 1.6%; and
glyUsu
GAA
, 0.4%. Mistranslation by these mutant glycine tRNA species has no adverse affects on cell growth since cultures possessing the suppressors grow as fast as cells without. The
supT
tRNA species can be observed as a peak in the profile of glycyl-tRNA fractionated on a RPC-5 chromatographic column, indicating that the mutant tRNA can be aminoacylated with reasonable efficiency. This finding contrasts with previous findings concerning the
glyUsu
AGA
mutant tRNA which is not significantly aminoacylated under the same conditions.
Protein Composition of the Outer Membrane of
Salmonella typhimurium
: Effect of Lipopolysaccharide Mutations
Authors: Ames Giovanna Ferro-Luzzi , Spudich Elena Negri , Nikaido Hiroshi
Published: January 2020

The protein composition of the outer membrane of
Salmonella typhimurium
has been analyzed by electrophoresis on slabs of sodium dodecyl sulfate-acrylamide gel. This powerful technique allows very high resolution of protein mixtures and has permitted the identification of multiple major protein components of the outer membrane; no evidence for a single major component of molecular weight 44,000 was obtained. These proteins were shown to be decreased in amount in mutants which have defective lipopolysaccharides. Mutants of an apparently new type were also found which contain decreased amounts of the proteins and the parent-like lipopolysaccharide, yet are resistant to a lipopolysaccharide-specific phage, C21. Several outer membrane proteins are insoluble in sodium dodecyl sulfate unless heated at high temperature (above 70 C). A purification procedure based on this property is tentatively suggested.
Derepressed Levels of the Isoleucine-Valine and Leucine Enzymes in
hisT1504
, a Strain of
Salmonella typhimurium
with Altered Leucine Transfer Ribonucleic Acid
Authors: Rizzino A. A. , Bresalier R. S. , Freundlich M.
Published: January 2020

A
hisT
mutant of
Salmonella typhimurium
was found to have altered regulation of the isoleucine-valine and leucine enzymes. These enzymes in the
hisT
strain were derepressed two- to eightfold over those of the parent wild-type strain when grown in minimal medium or under repressing conditions. The amount of tRNA
Leu
and the cellular concentration of charged tRNA
Leu
was about the same in the
hisT
strain and in the wild type. However, leucyl-tRNA from the mutant was chromatographically different from that of wild type, confirming previous reports that
hisT
strains have altered tRNA
Leu
. These results suggest strongly that tRNA
Leu
is involved in repression of the isoleucine-valine and leucine enzymes in
S. typhimurium
.
Structure and Immunochemistry of the Cell Wall Mannans from
Saccharomyces chevalieri, Saccharomyces italicus, Saccharomyces diastaticus
, and
Saccharomyces carlsbergensis
Authors: Ballou Clinton E. , Lipke Peter N. , Raschke William C.
Published: January 2020

The mannans of
Saccharomyces chevalieri, S. italicus, S. diastaticus
, and
S. carlsbergensis
, were acetolyzed, and the fragments were separated by gel filtration. All gave similar acetolysis fingerprints, which were distinguished from
S. cerevisiae
by the presence of a pentasaccharide component in addition to the mono-, di-, tri-, and tetrasaccharides. All oligosaccharide fragments were composed of mannose in α-linkage. From methylation analysis and other structural studies, the disaccharide was shown to be αMan(1 → 2)Man; the trisaccharide was shown to be a mixture of αMan(1 → 2)αMan (1 → 2)Man and αMan(1 → 3)αMan(1 → 2)Man; the tetrasaccharide was αMan(1 → 3)αMan(1 → 2)αMan(1 → 2)Man; and the pentasaccharide was αMan(1 → 3)αMan(1 → 3)αMan(1 → 2)αMan(1 → 2)Man. The ratios of the different fragments varied slightly from strain to strain. Mannanase digestion of two of the mannans yielded polysaccharide residues that were unbranched (1 → 6)-linked polymers, thus establishing the structural relationship between these mannans and that from
S. cerevisiae
. Antisera raised against the various yeasts cross-reacted with the mannans from each, and also with
S. cerevisae
mannan. The mannotetraose and mannopentaose acetolysis fragments gave complete inhibition of the precipitin reactions, which indicated that, in these systems as in the
S. cerevisiae
system, the terminal α(1 → 3)-linked mannose unit was the principal immunochemical determinant on the cell surface.
Ecology of Iron-Oxidizing Bacteria in Pyritic Materials Associated with Coal
Authors: Belly R. T. , Brock T. D.
Published: January 2020

A technique was developed for measuring
14
CO
2
uptake by chemolithotrophic bacteria directly in pyritic materials associated with coal and coal refuse. There was good correlation between
14
CO
2
uptake, as determined by this technique, and the most probable number of iron-oxidizing bacteria. Maximal
14
CO
2
uptake occurred in coal refuse material 2 to 3 years old, and only slight incorporation was demonstrated in fresh material or material 40 years old. Samples taken from the surface of the coal refuse pile always demonstrated maximal
14
CO
2
uptake, and in most samples, only slight activity was demonstrated at depths below 8 to 10 cm. Optimal uptake of
14
CO
2
by natural samples occurred at 20 to 30 C and at a moisture content of between 23 and 35%. In addition to chemolithotrophic bacteria, heterotrophic fungi and yeasts were also routinely isolated in high numbers from acidic coal refuse. In contrast, acidophilic, heterotrophic bacteria were either absent or present in low numbers in such acidic samples.
Degradative Effect of Phenol on Endotoxin and Lipopolysaccharide Preparations from
Serratia marcescens
Authors: Tsang J. C. , Wang C. S. , Alaupovic P.
Published: January 2020

It has been established that the well-known deproteinizing action of hot 45% aqueous phenol on whole cells or isolated and purified endotoxin of
Serratia marcescens
08 is caused by the cleavage of a phenol-sensitive linkage within the lipid moiety. As a result of this degradation, both the lipopolysaccharide and simple protein fragments retained a part of the lipid moiety. Although not proceeding at the same fast rate as the cleavage of the lipid moiety, such phenol treatment also caused a partial hydrolysis of the O-specific side chain and ester-bound fatty acids. Hydrolysis of the O-specific side chain accounted for 5% of the lipopolysaccharide and that of ester-bound fatty acids accounted for 11% of the total fatty acid content after 60 min of treatment. It is suggested that the presence of these degradation products is one of the main causes of the heterogeneity of endotoxin and lipopolysaccharide preparations.
Cellulase Localization in Hyphae ofAchlya ambisexualis
Authors: Nolan Richard A. , Bal Arya K.
Published: January 2020

Cellulase (EC 3.2.1.4; β-1, 4-glucan glucanohydrolase) was localized at the ultrastructural level and found to occur in dictyosomes and vesicles, around the periphery of unidentified storage bodies, between the plasmalemma and the cell wall, and on the outer surface of the cell wall in the male strain (E87) ofAchlya ambisexualisafter treatment with the sex hormone antheridiol.
Mutant of
Bacillus subtilis
Lacking Exo-β-
N
-Acetylglucosaminidase Activity
Authors: Ortiz Jose M.
Published: January 2020

A procedure for the isolation of exo-β-
N
-acetylglucosaminidase mutants, by using a plate assay method incorporating a fluorescent substrate, has been developed. A mutant lacking exo-β-
N
-acetylglucosaminidase activity has been isolated and shown to grow, divide, autolyze, and sporulate as well as the parental strain.
Effect of Ultraviolet-Sensitive Mutants on Gene Inheritance in Mycobacterial Matings
Authors: Mizuguchi Yasuo
Published: January 2020

Evidence is presented suggesting that a
rec
mutation in one strain (presumably female) of a mating pair of
Mycobacterium smegmatis
strains prevented the appearance of recombinants, whereas a
rec
mutation in the other strain (presumably male) did not.
Structure of O-Specific Side Chains of Lipopolysaccharides from
Yersinia pseudotuberculosis
Authors: Samuelsson Kurt , Lindberg Bengt , Brubaker Robert R.
Published: January 2020

Lipopolysaccharide prepared from cells of
Yersinia
(
Pasteurella
)
pseudotuberculosis
of serogroups I, II, III, IV, and V is known to contain the 3,6-dideoxyhexose (DDH) paratose, abequose, paratose, tyvelose, and ascarylose in its respective O-specific side chains. Lipopolysaccharides or lipid-free polysaccharides of all of the 10 known serogroups and subgroups were subjected to methylation analysis and determined as alditol acetates by gas-liquid chromatography and mass spectrometry. The results indicated that the O-specific side chains of nine serotypes are composed of oligosaccharide repeating units in the form of four alternative general structures in which a terminal DDH may vary. These structures are DDH [Formula: see text] 6-deoxy-
d
-
manno
-heptose [Formula: see text]
d
-galactose (serogroups IA, IIA, and IVB), DDH [Formula: see text]
d
-mannose [Formula: see text]
l
-fucose (serogroups IB and IIB), and two configurations similar to the latter except that the 4-position of
l
-fucose was either linked to the
d
-mannose residue (serogroups VA and VB) or to the DDH residue (serogroups III and IVA). In contrast, O-groups in lipopolysaccharide of the newly discovered serogroup VI contained the DDH colitose and 2-acetamido-2-deoxy-
d
-galactose. Accordingly, all five known types of DDH have now been detected in lipopolysaccharides of
Y. pseudotuberculosis
. The sugar 6-deoxy-
d
-
manno
-heptose, present in O-specific side chains of serogroups IA, IIA, and IVB, has not yet been reported to occur elsewhere in nature.
Effect of the Osmotic Pressure of the Growth Medium on
fabB
Mutants of
Escherichia coli
Authors: Broekman J. H. F. F. , Steenbakkers Johan F.
Published: January 2020

Temperature-sensitive, unsaturated fatty acid (
fabB
) auxotrophs of
Escherichia coli
can grow at the restrictive temperature in the absence of unsaturated fatty acid in a medium with a high osmotic pressure. If a mutant culture was starved for unsaturated fatty acids and harvested just before the lysis started, the fatty acid composition of the cells was the same as that of cells grown until late log phase in a high-osmotic medium. Evidence is presented that the in vivo unsaturated fatty acid biosynthesis is significantly increased in a high osmotic medium. The increase is probably due to a partial activation of the temperature-sensitive
fabB
product. Besides the stimulation of the temperature-sensitive
fabB
product, a minimal osmotic pressure of the medium appeared to be necessary to allow growth of cells containing lipids with a changed fatty acid composition.
fabA
mutants are unable to grow in a high-osmotic medium in the absence of unsaturated fatty acids. No increase in the in vivo unsaturated fatty acid biosynthesis could be detected in the temperature-sensitive
fabA
mutants.
Uptake of Nitrite by
Neurospora crassa
Authors: Schloemer Robert H. , Garrett Reginald H.
Published: January 2020

Like the nitrate transport system, the nitrite uptake system in
Neurospora crassa
is induced by either nitrate or nitrite. This induction is prevented by cycloheximide, puromycin, or 6-methyl purine. The

K
m

for nitrite of the induced nitrite uptake system is 86 μM, and the

V
max

is 100 μmol of nitrite per g (wet weight) per h. Nitrite uptake is inhibited by metabolic poisons such as arsenate, dinitrophenol, cyanide, and antimycin A. No repression or inhibition of the nitrite transport system by ammonia, nitrate, or Casamino Acids was observed.
Specificity in Deoxyribonucleic Acid Uptake by Transformable
Haemophilus influenzae
Authors: Scocca J. J. , Poland R. L. , Zoon Kathryn C.
Published: January 2020

Cells of
Haemophilus influenzae
strain Rd competent for genetic transformation irreversibly bound approximately five molecular fragments of
H. influenzae
deoxyribonucleic acid (DNA) per cell; under identical conditions, DNA derived from
Escherichia coli
B was not taken up (<1 molecule per 50 cells). Similarly, DNA from
Xenopus laevis
was not taken up by competent
H. influenzae
. Of the heterologous DNAs tested, only DNA from
H. parainfluenzae
interfered with the uptake of
H. influenzae
DNA, as judged by competition experiments employing either DNA binding or genetic transformation as the test system. The extracellular heterologous DNA did not suffer either single- or double-strand breakage upon exposure to competent
H. influenzae
.
Integration and Repair of Ultraviolet-Irradiated Transforming Deoxyribonucleic Acid in
Haemophilus influenzae
Authors: Muhammed Amir , Setlow Jane K.
Published: January 2020

The extent of association between donor transforming deoxyribonucleic acid (DNA) and recipient DNA in
Haemophilus influenzae
as a function of ultraviolet (UV) dose to the transforming DNA has been measured by isopycnic analysis of lysates of
3
H-labeled recipient cells exposed to DNA labeled with
32
P and heavy isotopes. Except for doses above 15,000 ergs/mm
2
, the results of these measurements are in good agreement with previous estimates made by another technique. Experiments with a mutant temperature sensitive for DNA synthesis and another mutant defective in excision of pyrimidine dimers suggest that the discrepancy between the methods of high doses results from DNA synthesis, in which portions of the associated donor DNA containing pyrimidine dimers are excised and broken down, and the components are reutilized for synthesis.

Repair of UV-irradiated, transforming DNA during incubation of recipient cells is observed as an increase in transforming ability when fractions from CsCl gradients of cell lysates are assayed on excision-deficient cells. When transforming DNA containing markers of different UV sensitivities is used, repair of the UV-resistant
nov
marker by excision proficient cells takes place exclusively in the donor DNA that is associated with recipient DNA, and this repair is observed even in the absence of DNA synthesis. However, no repair is observed in the case of the more UV-sensitive
str
marker, possibly because excision events may remove a large fraction of the integrated
str
markers in addition to repairing a small fraction of the integrated DNA containing this marker.
Polypeptide Formation and Polyribosomes in
Escherichia coli
Treated with Chloramphenicol
Authors: Cremer Kenneth J. , Silengo Lorenzo , Schlessinger D.
Published: January 2020

In
Escherichia coli
cultures maximally inhibited with chloramphenicol, formation of polypeptides still continued at a slow, constant rate for at least 90 min. The rate of leucine incorporation was reduced to 0.5%, but methionine was only reduced to 2%, suggesting that chains are normally initiated with methionine but are prematurely released at a short chain length. Consistent with this possibility was the distribution of the products on Sephadex columns: a range of peptides longer than 4 and shorter than 60 to 70 residues was seen. Less than 10% of the peptides broke down during a chase with cold amino acids, and during continuous labeling they accumulated progressively. On the average, one peptide was formed per ribosome every 5 min. Peptide synthesis in the presence of chloramphenicol was still dependent on ribosome translocation; it stopped in a mutant with an inactivated temperature-sensitive elongation factor G. But even in the absence of translocation, new messenger ribonucleic acid (mRNA) chains were found joined to one or a few ribosomes. The chains had a size distribution comparable to that of mRNA from polyribosomes of growing cells. They were stabilized for an average time of about 5 min, but were more rapidly degraded after puromycin was added to the cells. This suggests that stabilization may be related to the average time spent by a ribosome on an mRNA chain, with or without polypeptide formation.
Threonine Deaminase from a Mutant Requiring Isoleucine or Pyridoxine: Inability to Form a Tetrameric State
Authors: Grimminger H. , Feldner J.
Published: January 2020

Threonine deaminase from a mutant of
Escherichia coli
growing alternatively with isoleucine or pyridoxine is a dimer, whereas the wild-type enzyme is a tetramer.
Reduced Ferredoxin: CO
2
Oxidoreductase from
Clostridium pasteurianum:
Its Role in Formate Metabolism
Authors: Thauer R. K. , Fuchs G. , Jungermann K.
Published: January 2020

The activity of reduced ferredoxin: CO
2
oxidoreductase in
Clostridium pasteurianum
was correlated with the accumulation of formate in the growth medium. The data indicate that the in vivo function of the enzyme is to mediate formate synthesis rather than its degradation.
Bacterial Bioluminescence In Vivo: Control and Synthesis of Aldehyde Factor in Temperature-Conditional Luminescence Mutants
Authors: Cline Thomas W. , Hastings J. W.
Published: January 2020

Bioluminescent marine bacteria possess luciferase, which catalyzes the oxidation of reduced flavin mononucleotide and long-chain aldehyde to produce light. Temperature-sensitive mutants of these bacteria can be obtained which require exogenous aldehyde for light production at higher temperatures. In
Beneckea harveyi
. two classes of such mutants were found which differed with regard to their response to temperature shifts. In one class, a shift from permissive to nonpermissive temperature in liquid cultures resulted in a rapid (
t
½
≃ 3 min) loss of luminescence. In the other, there was no immediate decline in luminescence; it was the increase of luminescence that was blocked. Through studies of these and other effects of temperature shifts on the in vivo luminescence of these mutants, we conclude that at least two genes are specifically involved in the in vivo biosynthesis of aldehyde for the luminescence reaction and that both genes are coordinately controlled with that for luciferase.