bluuebunny/crossref_metadata_2025 huggingface dataset:
Mutants of
Escherichia coli
with a Growth Requirement for Either Lysine or Pyridoxine
Authors: Bukhari Ahmad I. , Taylor Austin L.
Published: January 2020

Two distinct phenotypic classes of lysine requiring auxotrophs of
Escherichia coli
are described. Mutants of the LysA class produce little or no active diaminopimelic acid (DAP) decarboxylase and specifically require lysine for growth. Mutants of the LysB class produce a cryptic DAP decarboxylase which can be activated both in vivo and in vitro by higher than normal levels of its cofactor, pyridoxal 5′-phosphate. The LysB mutants have an alternate requirement for lysine or pyridoxine. Both LysA and LysB mutations map at 55 min, close to the
thyA
locus of
E. coli
. The association between pyridoxal phosphate and DAP decarboxylase appears to be much weaker in LysB mutants than in wild-type bacteria, and the mutant enzyme also sediments more slowly than wild-type enzyme in sucrose density gradients. The results suggest that the LysB mutations alter a specific region (or subunit) of the enzyme molecule which is needed to stabilize the binding of pyridoxal phosphate. These studies help to resolve certain contradictory observations on DAP decarboxylase reported earlier and may have relevance to pyridoxal phosphate enzymes in general. Prototrophic revertants of LysB mutants arise by second site mutations that result in increased availability of intracellular pyridoxal phosphate. These revertants appear to be derepressed for pyridoxine biosynthesis.
Membranous Inclusions of
Pseudomonas aeruginosa
Authors: Carrick Lee , Berk Richard S.
Published: January 2020

Electron microscopy of sectioned cells of
Pseudomonas aeruginosa
treated with a double fixative in
N
-2-hydroxyethylpiperazine-
N
-2-ethanesulfonic acid revealed a number of membranous inclusions varying in size and morphology. One round, electron transparent form was frequently observed which did not routinely appear to be attached to the cytoplasmic membrane and varied in size from 120 to 300 nm in diameter. However, in one case, several tubular structures between an inclusion and the cytoplasmic membrane was observed. On rare occasions, a large and unusual multilayered inclusion consisting of three thick and distinct layers was also encountered. In addition, two small mesosomal structures were singly observed in cells and were situated proximal to the cytoplasmic membrane. One type appeared to consist of a single thin membrane, whereas the other type consisted of a delicate, multilayered structure.
Appendage Development in
Clostridium bifermentans
Authors: Samsonoff William A. , Hashimoto T. , Conti S. F.
Published: January 2020

The appendages of
Clostridium bifermentans
UK-A 1003 spores were shown to originate from a substance located just exterior to the outer forespore membrane. The dense spore coat develops along the periphery of this material, and, as the appendages develop in the cytoplasm, the coalescing spore coat intervenes between the appendages and their origin. Freeze etching revealed that the appendages are in the form of distinct fibers in proximity to the mature spore body. These fibers form a network around the spore, seemingly encasing it and insuring that the appendages remain attached to the mature, free spore. The inner wall of each appendage tubule is lined with fibers whereas the outer surface is smooth. The developing exosporium contained several layers consisting of small (3 nm) globular subunits; the outer exosporial surface is composed of relatively unstructured material.
Scanning Electron Microscopic Studies of
Candida albicans
Authors: Barnes W. G. , Flesher A. , Berger A. E. , Arnold J. D.
Published: January 2020

A scanning electron microscopic study of selected morphological stages of
Candida albicans
is presented. Stages represented are budding yeast cells, mycelial-like forms, chlamydospores, germ tube formation, and an unusual rough cell type.
In Vitro Ribonucleic Acid Synthesis in the Zoospores of the Aquatic Fungus
Blastocladiella emersonii
Authors: Horgen Paul A.
Published: January 2020

The zoospores of
Blastocladiella emersonii
posses three ribonucleic acid polymerases. No general or specific inhibitor for the enzymes were found in the protoplasm of the spores.
Salmonella
Locus Affecting Phosphoenolpyruvate Synthase Activity Identified by a Deletion Analysis
Authors: Calvo J. M. , Goodman M. , Salgo M. , Capes N.
Published: January 2020

Strain
leu-4017
, derived from
Salmonella typhimurium
LT2, cannot utilize acetate, pyruvate, or citric acid cycle intermediates as sole sources of carbon. The mutation in this strain extends from the A cistron of the leucine operon to some point between
leu
and
azi
, presumably deleting one or more loci involved in the utilization of these compounds. One of these loci is required for phosphoenolpyruvate synthase activity.
Hyphal Wall Compositions of Marine and Terrestrial Fungi of the Genus
Leptosphaeria
Authors: Szaniszlo Paul J. , Mitchell Ralph
Published: January 2020

Hyphal wall compositions of six
Leptosphaeria
species were compared to assess whether gross changes have occurred in the hyphal wall chemistry of closely related fungi which have become ecologically restricted to marine or terrestrial habitats. Unfractionated, lipid-extracted hyphal walls of each
Leptosphaeria
species had qualitatively identical compositions consisting of glucose, mannose, galactose, glucosamine, amino acids, and traces of galactosamine. Quantitative analyses showed that the hyphal wall components varied from species to species. Qualitative compositions of alkali-soluble wall fractions from each species were identical and contained the same sugars found in the unfractionated walls. The alkali-insoluble residues contained glucose, glucosamine, and amino acids. The alkali-soluble fractions were composed predominantly of glucose, galactose, and mannose. The alkali-insoluble fractions contained high concentrations of glucose and glucosamine and relatively low concentrations of amino acids.
Transduction of R Factors by a
Proteus mirabilis
Bacteriophage
Authors: Nakaya Rintaro , Rownd R.
Published: January 2020

A transducing phage, designated φm, was isolated from a lysogenic strain of
Proteus mirabilis
and was characterized with respect to its physical and genetic properties. The phage contains double-stranded deoxyribonucleic acid (DNA) with an S
20,w
° of 29 which corresponds to a molecular weight of 24 × 10
6
daltons. The base composition of φm DNA was estimated to be 40% guanine plus cytosine on the basis of the buoyant density of the DNA. φm carries out generalized transduction of chromosomal genes in
P. mirabilis
at a frequency of 5 × 10
−8
to 2 × 10
−6
per adsorbed phage. To obtain R-factor transduction, it was necessary to have a resident R factor in the recipient cells. In these experiments, different combinations of genetically distinguishable R factors were used in the donor and recipient cells. The frequencies of R-factor transduction were 10
−9
to 2 × 10
−8
. The transduction of R factors using an R
−
recipient could not be detected. Transductant R factors were usually recombinant between donor and resident R factors. All of the transduced R factors were transferable by conjugation. A plausible explanation for the requirement for a resident R factor in the recipient cells is that φm transduces only a portion of the R-factor genome and therefore requires a resident R factor for genetic recombination. The reason for the low frequencies of R-factor transduction is not known, but some possible interpretations have been discussed.
Phenylalanine Biosynthesis in
Escherichia coli
K-12: Mutants Derepressed for Chorismate Mutase P-Prephenate Dehydratase
Authors: Im S. W. K. , Pittard J.
Published: January 2020

Mutants were isolated which are derepressed for the synthesis of chorismate mutase P-prephenate dehydratase. No other enzymes involved in the synthesis of phenylalanine are derepressed in these strains. These mutants are able to grow in concentrations of
o
- and
p
-fluorophenylalanine that inhibit the growth of AB3259, the strain from which they were derived. They also excrete phenylalanine. Genetic analysis shows that the mutations causing this derepression are closely linked to the structural gene for this enzyme (cotransduction frequency of 95% or more with
pheA
). The gene in which they occur has been designated
pheO
since this gene has all of the properties predicted for an operator gene controlling the
pheA
structural gene. Finally, the
pheO
mutant alleles have been shown to be dominant in diploids.
Isolation and Characterization of Tricarboxylic Acid Cycle Mutants ofBacillus subtilis
Authors: Carls R. A. , Hanson R. S.
Published: January 2020

A technique was developed for the detection, on agar, of mutants ofBacillus subtilisthat lacked a functional tricarboxylic acid cycle. Mutants devoid of detectable levels of aconitase, isocitric dehydrogenase, alpha-ketoglutarate dehydrogenase, succinic dehydrogenase, fumarase, and malate dehydrogenase have been isolated and characterized. Several mutants with conditionally expressible lesions, including a mutant with a heat-sensitive citrate synthase, have also been isolated. All of the mutants examined express all the biochemical markers normally absent in early-stage sporulation mutants except elastase, and some of these mutants sporulated nearly as well as the prototroph.
Mucopolysaccharide Which Regulates Growth in
Neurospora
Authors: Reissig José L. , Glasgow James E.
Published: January 2020

Neurospora
produces a mucopolysaccharide (called MP) which inhibits its growth, causes vacuolation and agglutination of its cells, and precipitates its purified membrane protein. Cultures of a colonial strain display a phase of slow growth; the induction of this phase is traced to the production of MP by the mold. Stationary-phase cultures of wild type also produce MP. MP is a polymer of galactosamine, its amino groups only partially acetylated, probably containing other minor components. MP molecular weight is approximately 10
6
. Complete acetylation abolishes the biological activities of MP. It is suggested that the regulatory effect of MP is mediated by its interaction with the protoplasmic membrane.
Role of Pyridine Nucleotides in 5-Fluorouracil-Mediated Reactivation of Ultraviolet Radiation Damage
Authors: Boyle J. M. , Schenley R. L. , Swenson P. A.
Published: January 2020

Ultraviolet irradiation (520 ergs/mm
2
at 254 nm) causes the respiration of
Escherichia coli
B/r cells to cease after about 90 min postirradiation incubation in a minimal medium containing glycerol as the sole source of carbon. The cessation of respiration is associated with loss of pyridine nucleotides. Agents which interfere with postirradiation transcription and translation prevent cessation of respiration. We have studied the effects of one of these agents, 5-fluorouracil (FU), on respiration, pyridine nucleotide levels, viability, capacity to support phage growth, and the repair of irradiated deoxyribonucleic acid (DNA). Addition of FU to cells immediately after irradiation results in the continuance of respiration at a linear rate and the maintenance of high levels of pyridine nucleotides. Cellular viability increases dramatically during the first 60 min of postirradiation incubation in the presence of FU. The ability of irradiated cells to support the growth of phage T4 is also greatly increased. FU treatment has no effect on the kinetics of pyrimidine dimer excision or the degradation of DNA. However, treated cells repair single-strand breaks resulting from early steps in excision repair slightly more efficiently than do untreated cells. The results support the hypothesis that one of the causes of death in these irradiated cells is the disappearance of pyridine nucleotides, coenzymes of certain respiratory dehydrogenases, and, in the case of nicotinamide adenine dinucleotide, for polynucleotide ligase, the enzyme responsible for the final step in the repair of DNA.
Repair of Radiation Damage to Deoxyribonucleic Acid in Germinating Spores of
Bacillus subtilis
Authors: Terano Hiroshi , Tanooka Hiroshi , Kadota Hajime
Published: January 2020

The repair of deoxyribonucleic acid (DNA) in germinating spores was studied in comparison with that in vegetative cells. Radiation-induced single-strand breaks in the DNA of spores and of vegetative cells of
Bacillus subtilis
were rejoined during postirradiation incubation. The molecular weight of single-stranded DNA was restored to the level of nonirradiated cells. The rate of the rejoining of DNA strand breaks in irradiated spores was essentially equal to that in irradiated vegetative cells. The rejoining in spores germinating in nutrient medium occurred in the absence of detectable DNA synthesis. In this state, normal DNA synthesis was not initiated. Very little DNA degradation occurred during the rejoining process. On the other hand, in vegetative cells the rejoining process was accompanied by a relatively large amount of DNA synthesis and DNA degradation in nutrient medium. The rejoining occurred in phosphate buffer in vegetative cells but not in spores in which germination was not induced. Chloramphenicol did not interfere with the rejoining process in either germinating spores or vegetative cells, indicating that the rejoining takes place in the absence of de novo synthesis of repair enzyme. In the radiation-sensitive strain uvs-80, the capacity for rejoining radiation-induced strand breaks was reduced both in spores and in vegetative cells, suggesting that the rejoining mechanism of germinating spores is not specific to the germination process.
Effect of 2-Deoxyglucose on Cell Wall Formation in
Saccharomyces cerevisiae
and Its Relation to Cell Growth Inhibition
Authors: Biely P. , Krátký Z. , Kovařík J. , Bauer Š.
Published: January 2020

The growth inhibition and the lysis of
Saccharomyces cerevisiae
caused by 2-deoxy-
d
-glucose (2-DG) were shown to be a consequence of unbalanced cellular growth and division. The lysis, but not the repression of growth and osmotic fragility of cells, could be suppressed by the addition of mannitol as an osmotic stabilizer. This result, as well as the morphological changes observed in the cells and changes in the chemical composition of the cell walls, showed that
S. cerevisiae
grown in the presence of 2-DG formed weakened cell walls responsible for the osmotic fragility. Evidence is presented for the first time demonstrating the incorporation of 2-DG into yeast cell wall material. Other data suggest that the inhibition of yeast growth by 2-DG results from an interference of phosphorylated metabolites of 2-DG with metabolic processes of glucose and mannose involved in the synthesis of structural cell wall polysaccharides.
Enzymes of Carbohydrate Metabolism in
Thiobacillus
species
Authors: Matin Abdul , Rittenberg Sydney C.
Published: January 2020

A study was made of enzymes of carbohydrate metabolism in representative thiobacilli grown with and without glucose. The data show that
Thiobacillus perometabolis
possesses an inducible Entner-Doudoroff pathway and is thus similar to
T. intermedius
and
T. ferrooxidans. T. novellus
lacks this pathway. Instead, a non-cyclic pentose phosphate pathway along with the Krebs cycle is apparently the major route of glucose dissimilation in this organism. Glucose does not support or stimulate the growth of strains of
T. neapolitanus, T. thioparus
, and
T. thiooxidans
examined, nor does its presence in the growth medium greatly influence their enzymatic constitution. These obligately chemolithotrophic thiobacilli do not possess the Entner-Doudoroff pathway. Their nicotinamide adenine dinucleotide (NAD)-linked isocitrate dehydrogenase activity predominates over their nicotinamide adenine dinucleotide phosphate (NADP)-linked activity; the converse is true for the other thiobacilli. The data suggest that NAD-linked isocitrate dehydrogenase activity in thiobacilli is involved in biosynthetic reactions.
Glucosylation of Teichoic Acid: Solubilization and Partial Characterization of the Uridine Diphosphoglucose:Polyglycerolteichoic Acid Glucosyl Transferase from Membranes of
Bacillus subtilis
Authors: Brooks David , Mays Laura L. , Hatefi Y. , Young Frank E.
Published: January 2020

Polyglycerolteichoic acid:glucosyl transferase (TAG transferase), one of the three enzymes involved in the pathway leading to the glucosylation of teichoic acid in
Bacillus subtilis
168, was investigated. During the early stages of the growth of
B. subtilis
, TAG transferase is predominantly a soluble enzyme found in the cytoplasm. As growth proceeds, the amount of soluble enzyme decreases and the proportion of insoluble, membrane-bound TAG transferase increases, reaching a maximal value at the close of the logarithmic phase. Data are presented which suggest that these are two forms of the same enzyme, or have some common component. The effects of chaotropic agents, such as sodium trichloroacetate and sodium perchlorate, on the cytoplasmic membrane were also studied. These data show that such compounds can effectively remove the TAG transferase from the membrane in a water-soluble form. A study of some of the physical properties of this solubilized enzyme suggests that there is little difference between the two forms of the enzyme. Experiments are described which indicate that the glucosyl transfer by both the membrane-bound and soluble enzymes is not mediated by lipids.
Characterization of the Membrane-Bound Succinic Dehydrogenase of
Micrococcus lysodeikticus
Authors: Pollock Jerry J. , Linder Regina , Salton Milton R. J.
Published: January 2020

The occurrence of succinic dehydrogenase [succinic:(acceptor) oxidoreductase, EC 1.3.99.1] in membrane fractions of
Micrococcus lysodeikticus
was investigated. The enzyme could be purified 10-fold, by deoxycholate treatment. Butanol extraction of membranes yielded an active fraction, nonsedimentable at 130,000 ×
g
for 2 hr and altered in its phospholipid content relative to membranes. The activity of the enzyme in particulate preparations was decreased in the presence of competitive inhibitors and by compounds known to react with iron, sulfhydryl groups, and flavine. In this respect, the bacterial succinic dehydrogenase is similar to the enzyme derived from yeast and mammalian sources. In certain membrane fractions, Ca
2+
and Mg
2+
exhibited inhibitory effects whereas Triton X-100 caused activation. The enzyme could also be activated by substrate. In the phenazine reductase assay, incomplete reduction of electron acceptor was observed upon addition of divalent cations and iron binding agents.
Giant Cysts and Cysts with Multiple Central Bodies in
Azotobacter vinelandii
Authors: Cagle G. D. , Vela G. R.
Published: January 2020

Cyst germination in
Azotobacter vinelandii
ATCC 12837 was studied by using phase contrast and electron microscopy. Germination in this organism was accompanied by the formation of large cyst forms of two different types: giant cysts and cysts containing multiple central bodies. Previously, these two types have been reported only when yeast extract was added to the encystment medium. In this study, we observed giant cysts and cysts with multiple central bodies in nitrogen-free liquid medium. The germination of “normal” cysts is often preceded by enlargement to the giant form and division of the central body to produce cysts with multiple central bodies. Structures similar in appearance to ribosomal aggregates were observed only in cysts undergoing pregermination transformations.
Ultrastructure of the Cell Wall of
Erwinia amylovora
Authors: Huang Pi-Yu , Goodman Robert N.
Published: January 2020

Thin sectioned cells of
Erwinia amylovora
revealed two electron-dense layers in their walls when fixed at 24 to 27 C and three when fixed at 4 C.
Mating Responses in
Candida lipolytica
Authors: Herman A. I.
Published: January 2020

Culture medium that restricted cell multiplication increased fertility in selected heterothallic stocks of
Candida lipolytica
and triggered sporulation in newly formed diploids; a medium that supported vigorous cell growth prevented sporulation and permitted the newly formed diploids to bud.
Variation in the Proportion of 50
S
and 30
S
Ribosomal Subunits at Different Growth Rates
Authors: Michaels George A.
Published: January 2020

The ratio of 50
S
to 30
S
native ribosomal subunits varies in a systematic way with the growth rate in a 15T
−
strain of
Escherichia coli
.
Allelic Variability in Comparative Complementation Confirming that the
adel2
-Specified Protein of Yeast is Bifunctional
Authors: Dorfman Ben-Zion
Published: January 2020

Mutants at the
adel2
locus of
Saccharomyces cerevisiae
are deficient in adenylosuccinate synthetase and are also responsible for constitutive purine biosynthetic activity. Ninety-six alleles were tested for restoration of each of these functions by allelic complementation and the results from the two types of test of every allele pair in the two matrices were compared with each other. Either the reactions were consistent, both complementing or noncomplementing, or inconsistent, with either enzymatic or regulatory function restored. The frequency and distribution of inconsistent behavior accords with the expectation that the
adel2
locus specifies a bifunctional protein serving independent roles in enzymatic activity and in regulation of pathway activity. In a parallel experiment and analysis the addition of 1.0
m
KCl increases the overall frequency of positive complementation, but skews the distribution of inconsistency sharply toward restoration of the regulatory function.
New Suppressor in
Escherichia coli
Authors: Russell R. R. B. , Pittard A. J.
Published: January 2020

During the genetic mapping of a mutation in the
pheS
gene which confers temperature sensitivity on a strain of
Escherichia coli
K-12, an extragenic suppressor was discovered which restores ability to grow at the restrictive temperature. The suppressor, which has been named
supQ
, is cotransduced by bacteriophage P1 with the
purE
marker.
SupQ
does not suppress a number of amber or ochre mutations.
SupQ
−
is carried by the prototrophic Hfr Hayes strain AB259, and the presence of the
supQ
−
allele impairs the growth of this strain at 42 C.
Studies on the Physiology of
Bacillus fastidiosus
Authors: Kaltwasser H.
Published: January 2020

Bacillus fastidiosus
was grown in a minimal medium that contained uric acid or allantoin, aerated by vigorous stirring. A constant, optimum
p
H of 7.4 was maintained by controlled addition of sulfuric acid. Washed cells converted both urate and allantoin into carbon dioxide and ammonia, simultaneously assimilating part of the available carbon and nitrogen. Urate oxidase (formerly called uricase) was present in extracts from urate-grown but not allantoin-grown cells. The formation of urate oxidase was apparently induced by urate. Urea was detected as an intermediate in some but not all of these experiments. However, the high urease activity observed in cell-free extracts may have prevented accumulation of urea in many of the experiments. The presence of glyoxylate carboligase and tartronic semialdehyde reductase activities indicates that the glycerate pathway may be involved in urate and allantoin catabolism in this organism.
Electron Microscopy During Release and Purification of Mesosomal Vesicles and Protoplast Membranes from
Staphylococcus aureus
Authors: Popkin Terry J. , Theodore Theodore S. , Cole Roger M.
Published: January 2020

The mesosomes of log-phase
Staphylococcus aureus
ATCC 6538P and
Staphylococcus aureus
phage-type 80/81, as seen in situ in ultrathin sections, were of the vesicular type. The constituent vesicles ranged from 35 to 50 nm in diameter when the glutaraldehyde-osmium-uranium-lead sequence of fixation and staining was used. During protoplasting in hypertonic buffer containing a muralytic enzyme, vesicles of the same size were extruded and required magnesium ion to maintain structural integrity. The vesicles, purified from the protoplasting supernatant medium by density gradient centrifugation, maintained size and configuration in a homogeneous preparation. Cytoplasmic membranes, produced by osmotic shock and nuclease treatment of protoplasts, were similarly concentrated in gradients. However, they were not free of membrane-associated ribosomes nor of mesosomal vesicles except when prepared in the absence of magnesium.
Polysome Turnover During Amino Acid Starvation inEscherichia coli
Authors: Ron Eliora Z.
Published: January 2020

The experiments presented in this paper support earlier evidence that ribosomes are released from polysomes when they encounter a codon for which no charged transfer ribonucleic acid is available. However, it is further shown that these ribosomes then reinitiate and resume translation. The size and the level of polysomes during deprival of an amino acid is a function of the frequency with which that particular amino acid appears in cellular proteins. Polysomes from starved cells are more stable than those from growing cells, and, moreover, polysomes from starved relaxed strains are more stable than those from starved stringent strains.
Heterotrophic Metabolism of the Chemolithotroph
Thiobacillus ferrooxidans
Authors: Tabita Robert , Lundgren D. G.
Published: January 2020

Glucose-6-phosphate dehydrogenase and the enzymes of the Entner-Doudoroff pathway, 6-phosphogluconate dehydrase and 2-keto-3-deoxy-6-phosphogluconate aldolase (assayed together), are induced during heterotrophic growth of
Thiobacillus ferrooxidans
on an iron-glucose-supplemented medium or on glucose alone. By contrast, autotrophic cells (iron-grown) contain low levels of these enzymes. Fructose 1, 6-diphosphate aldolase, an enzyme of the Embden-Meyerhof pathway, is present at low levels irrespective of the growth medium, suggesting that this enzyme is not involved in energy-yielding reactions but merely provides intermediates for biosynthesis. The Entner-Doudoroff and pentose-phosphate pathways are the principle means through which glucose is dissimilated and is presumed to be concerned with energy production. Isotopic studies showed that a high rate of CO
2
formation from specifically labeled glucose came from carbon atoms 1 and 4. An unexpectedly high rate of evolution of CO
2
also came from carbon 6, suggesting that the triose phosphate formed during glucose breakdown and specifically as a result of 2-keto-3-deoxy-6-phosphogluconate aldolase activity, was metabolized via some unorthodox metabolic route. Cells grown in the iron-supplemented and glucose-salts media have a complete tricarboxylic acid cycle, whereas autotrophically grown
T. ferrooxidans
lacked both α-ketoglutarate dehydrogenase and reduced nicotinamide adenine dinucleotide oxidase. Two isocitrate dehydrogenases [nicotinamide adenine dinucleotide (NAD) and NAD phosphate (NADP) specific] were present. NAD-linked enzyme was constitutive, whereas the NADP-linked enzyme was induced upon adaptation of autotrophic cells to heterotrophic growth.
Localization and Solubilization of Colicin Receptors
Authors: Sabet Sohair Farid , Schnaitman Carl A.
Published: January 2020

Envelope fractions isolated from
Escherichia coli
K-12 C600 and from colicin-resistant and colicin-tolerant (Tol II) mutants derived from this strain were separated on sucrose gradients into cell wall-enriched and cytoplasmic membrane-enriched fractions. These fractions were tested for their ability to neutralize colicins of the E and K groups. Neutralization activity was found in the cell wall-enriched fraction from the parent and the Tol II mutant but was absent from all fractions from the resistant mutant. This was also tested with several other
E. coli
strains. In all cases, sensitive strains contained the neutralization activity, whereas resistant strains did not. The neutralization activity was solubilized from cell walls or cell envelopes of sensitive or Tol II strains by extraction at room temperature with Triton X-100 plus ethylenediaminetetraacetic acid. The solubilized activity was precipitated by 20% ammonium sulfate, 70% ethanol, or 10% trichloroacetic acid. The activity was destroyed by treatment of the solubilized preparation with trypsin or periodate. These results suggest that this colicin-neutralization activity is due to the presence of specific receptors localized in the cell wall and that intact protein and a carbohydrate are required for this receptor to bind colicin.
Structural Changes in
Clostridium botulinum
Type E After Treatment with Boticin S5
1
Authors: Ellison Jane S. , Mattern Carl F. T. , Daniel Wendell A.
Published: January 2020

Treatment with boticin S5
1
, a bacteriocin produced by a nontoxigenic organism closely related to
Clostridium botulinum
type E, caused extensive changes in the structure of a sensitive
C. botulinum
type E strain. Nucleoid deoxyribonucleic acid, normally seen as fine filaments scattered throughout the cell, was aggregated into dense deoxyribonucleic acid masses. Mesosomes appeared to undergo structural rearrangement from lamellar to vesicular configuration. Eventual dissolution of cell contents left bacterial ghosts composed of seemingly intact cell walls with remnants of the cytoplasmic membrane and internal structures. The morphological changes observed in boticin-treated strain 070 cells were very similar to those produced by a bacteriocin-like substance from phage type 71
Staphylococcus aureus
on sensitive β-hemolytic streptococci. A similarity in the mode of action of the two bactericidal agents is suggested.
Solubilization of the Cytoplasmic Membrane of
Escherichia coli
by Triton X-100
Authors: Schnaitman Carl A.
Published: January 2020

Treatment of a partially purified preparation of cell walls of
Escherichia coli
with Triton X-100 at 23 C resulted in a solubilization of 15 to 25% of the protein. Examination of the Triton-insoluble material by electron microscopy indicated that the characteristic morphology of the cell wall was not affected by the Triton extraction. Contaminating fragments of the cytoplasmic membrane were removed by Triton X-100, including the fragments of the cytoplasmic membrane which were normally observed attached to the cell wall. Treatment of a partially purified cytoplasmic membrane fraction with Triton X-100 resulted in the solubilization of 60 to 80% of the protein of this fraction. Comparison of the Triton-soluble and Triton-insoluble proteins from the cell wall and cytoplasmic membrane fractions by polyacrylamide gel electrophoresis after removal of the Triton by gel filtration in acidified dimethyl formamide indicated that the detergent specifically solubilized proteins of the cytoplasmic membrane. The proteins solubilized from the cell wall fraction were qualitatively identical to those solubilized from the cytoplasmic membrane fraction, but were present in different proportions, suggesting that the fragments of cytoplasmic membrane which are attached to the cell wall are different in composition from the remainder of the cytoplasmic membrane of the cell. Treatment of unfractionated envelope preparations with Triton X-100 resulted in the solubilization of 40% of the protein, and only proteins of the cytoplasmic membrane were solubilized. Extraction with Triton thus provides a rapid and specific means of separating the proteins of the cell wall and cytoplasmic membrane of
E. coli
.
Nucleoside Triphosphate Pools in Synchronous Cultures of
Escherichia coli
Authors: Huzyk Lydia , Clark D. Joseph
Published: January 2020

Endogenous nucleoside triphosphate pools in synchronized cultures of
Escherichia coli
B/r/1 oscillate as a function of age. Purine nucleoside triphosphates show a gradual 50% increase from zero age to the time of subsequent division, immediately prior to division. In contrast, pyrimidine nucleoside triphosphates undergo a dramatic change of about 50% in the first half of the generation at a time coincident with the termination of a round of deoxyribonucleic acid replication. A 50 to 70% increase starts at the initiation of the next round of deoxyribonucleic acid replication and continues until cell division, in parallel with the purine nucleotides. The fluctuation of pyrimidines between zero age and the middle of the division cycle suggests a functional relationship for pyrimidine metabolism and the regulation of cell division.
Mutants of
Escherichia coli
Unable to Make Protein at 42 C
Authors: Russell R. R. B. , Pittard A. J.
Published: January 2020

Members of a collection of mutants of
Escherichia coli
unable to form colonies on nutrient agar at 42 C have been characterized on the basis of their growth response to a shift from 32 to 42 C in liquid medium. Forty-four mutants, which show an abrupt, nonlethal cessation of growth when moved to the restrictive temperature, have been characterized with respect to the effect of the mutation responsible for temperature sensitivity on deoxyribonucleic acid, ribonucleic acid, and protein synthesis. In 12 mutants, the mutation causing temperature sensitivity of growth primarily affects protein synthesis, in each case through an altered aminoacyl-transfer ribonucleic acid synthetase. Mutants with temperature-sensitive glutamyl-, phenylalanyl-, and valyl-transfer ribonucleic acid synthetases have been obtained, and the genes specifying these enzymes have been mapped by conjugation and transduction. Another mutant has been shown to possess a temperature-sensitive tryptophanyl-transfer ribonucleic acid synthetase, but this is not responsible for inability to grow at 42 C on media containing tryptophan.
Electrophoretic Heterogeneity of Bacterial Nicotinamide Adenine Dinucleotide Phosphate-Specific Isocitrate Dehydrogenases
Authors: Rowe John J. , Reeves Henry C.
Published: January 2020

The specific activities of the nicotinamide adenine dinucleotide phosphate-dependent isocitrate dehydrogenase in crude cell-free extracts of 15 different microorganisms, grown aerobically in simple mineral salts media containing glucose as the sole carbon source, ranged from a maximum of 0.820 in
Pseudomonas aeruginosa
to a minimum of 0.145 in
Thiobacillus novellus
. Polyacrylamide gel electrophoresis indicated that the bacterial species studied contained electrophoretically distinct proteins exhibiting isocitrate dehydrogenase activity. The electrophoretic mobilities, as well as the differences in stability of the enzyme observed in this study, indicate that the physical and chemical properties of isocitrate dehydrogenase may differ widely between bacterial species.
Analysis for Antigenic Similarities Among the 30
S
Ribosomal Proteins of
Escherichia coli
Authors: Strnad Bruce C. , Sypherd Paul S.
Published: January 2020

Antiserum was made against a single 30
S
protein, 30
S
-7. The amount of complement fixed by total 30
S
protein in the presence of this antiserum indicated that protein 30
S
-7 was the major antigen in the mixture of proteins. Each of the 30
S
ribosomal proteins was tested for cross-reactivity with anti-30
S
-7. This was done by determining if any of the other 30
S
proteins inhibited complement fixation by 30
S
-7. None of the other 30
S
proteins was found to inhibit complement fixation by 30
S
-7, indicating that 30
S
-7 is antigenically distinct from the other proteins.
Amino Acids of the Cell Wall of
Nocardia rubra
Authors: Beaman B. L. , Kim K. S. , Salton M. R. J. , Barksdale L.
Published: January 2020

Two classes of preparations of cell walls of
Nocardia rubra
strain 721-A, digested by trypsin and pepsin with or without subsequent extraction in alkaline ethanol, when examined by electron microscope and analyzed quantitatively for amino acid content differ in ultrastructure and constituent amino acids. Evidence suggests that the lipid-associated amino acids (as peptide or protein) occupy a location superficial to the basal peptido-glycan layer of this nocardia. Their removal is associated with the loss of a characteristic pattern of the outer envelope.
Inorganic Nitrogen Assimilation in Yeasts: Alteration in Enzyme Activities Associated with Changes in Cultural Conditions and Growth Phase
Authors: Thomulka Kenneth W. , Moat Albert G.
Published: January 2020

Ammonia assimilation has been investigated in four strains ofSaccharomyces cerevisiaeby measuring, at intervals throughout the growth cycle, the activities of several enzymes concerned with inorganic ammonia assimilation. Enzyme activities in extracts of cells were compared after growth in complete and defined media. The effect of shift from growth in a complete to growth in a defined medium (and the reverse) was also determined. The absence of aspartase (EC 4.3.1.1,l-aspartate-ammonia lyase) activity, the low specific activities of alanine dehydrogenase, glutamine synthetase [EC 6.3.1.2,l-glutamate-ammonia ligase (ADP)], and the marked increase in activity of the nicotinamide adenine dinucleotide phosphate-linked glutamate dehydrogenase (NADP-GDH) [EC 1.4.1.4,l-glutamate:NADP-oxidoreductase (deaminating)] during the early stages of growth support the conclusion that yeasts assimilate ammonia primarily via glutamate. The NADP-GDH showed a rapid increase in activity just before the initiation of exponential growth, reached a maximum at the mid-exponential stage, and then gradually declined in activity in the stationary phase. The NADP-GDH reached a higher level of activity when the yeasts were grown on the defined medium as compared with complete medium. The nicotinamide adenine dinucleotide-linked glutamate dehydrogenase (NAD-GDH) [EC 1.4.1.2,l-glutamate:NAD-oxidoreductase (deaminating)] showed only slight increases in activity during the exponential phase of growth. There was an inverse relationship in that the NADP-GDH increased in activity as the NAD-GDH decreased. The NAD-GDH activity was higher after growth on the complete medium. The glutamate-oxaloacetate transaminase (EC 2.6.1.1.l-aspartate:2-oxoglutarate aminotransferase) activity rose and fell in parallel with the NADP-GDH, although its specific activity was somewhat lower. Although other ammonia-assimilatory enzymes were demonstrable, it seems unlikely that their combined activities could account for the remainder of the ammonia-assimilatory capacity not accounted for by the NADP-GDH. The ability of aspartate to serve as effectively as glutamate as the sole source of nitrogen for the growth of yeast apparently resides in their ability to utilize aspartate for amino acid biosynthesis via transamination.
Events Occurring Near the Time of Synapsis During Transformation in
Diplococcus pneumoniae
Authors: Collins Carolyn J. , Guild Walter R.
Published: January 2020

A marker-specific and strongly temperature-dependent reaction was observed to occur at a time during transformation in
Diplococcus pneumoniae
after the donor deoxyribonucleic acid (DNA) had acquired single-strand properties and immediately preceding the integration of these strands into the recipient chromosome. Operationally, it was observed as the prevention of an intracellular inactivation process, also described in this paper, which is specific for low molecular weight or for damaged DNA, and which occurs if the recipient cells are held at suboptimal temperatures after the DNA has entered. Brief exposure of the cells to a higher temperature stabilized the DNA against this inactivation, in a two step process. It is the first step which has a strong temperature dependence (ΔH‡ = 70 kcal/mole, ΔS‡ = 160 entropy units), is marker specific, and which appears to be reversible. The second step is much less temperature-dependent and overlaps in time the start of integration. The enthalpy and entropy of activation are both consistent with those needed to open a loop of six to eight base pairs in a DNA duplex. It is suggested that these observations may reflect, and provide an assay for, the kinetics of synapsis, which on this model is limited in rate by the appearance of unpaired regions on the recipient duplex.
Biosynthesis of 50
S
Ribosomal Proteins During the Outgrowth of
Bacillus subtilis
Spores
Authors: Shaw Marlene V. , Armstrong Robert L.
Published: January 2020

The biosynthesis of 14 protein bands from 50
S
ribosomes was studied during the outgrowth of
Bacillus subtilis
W23 spores. The time at which the synthesis of each protein band begins and the patterns of synthesis that each displays were determined by comparing the incorporation of
3
H-phenylalanine during five intervals throughout the first hour of outgrowth with the incorporation of
14
C-phenylalanine between 145 and 150 min. The majority of the proteins in the 14 bands analyzed were synthesized as early as 5 to 10 min. The bands could be grouped on the basis of their labeling patterns as well as the time required for them to achieve a high rate of synthesis. Three bands did not achieve a high rate of synthesis until after 30 min of outgrowth, and at least one of the proteins from these bands appeared to be located on the exterior of the 50
S
subunit. The significance of the proteins from these three bands is discussed in terms of the late formation of new, mature 50
S
subunits during outgrowth.
Transfection of
Staphylococcus aureus
with Bacteriophage Deoxyribonucleic Acid
Authors: Sjöström Jan-Eric , Lindberg Martin , Philipson Lennart
Published: January 2020

Staphylococcus aureus
cells of strain 8325 (N) are competent for phage deoxyribonucleic acid (DNA) when harvested in the early exponential growth phase. Phenotypic expression of the competence requires divalent cations, and calcium ions are most effective. Treatment of phage DNA with deoxyribonuclease completely destroys infectivity and heat-denaturated DNA is not infectious. The highest frequency of transfection is around 10
4
plaque-forming units per μg of DNA.
Development of Respiration and Mitochondria in
Mucor genevensis
After Anaerobic Growth: Absence of Glucose Repression
Authors: Clark-Walker G. D.
Published: January 2020

Respiration and mitochondria in
Mucor genevensis
, a facultatively anaerobic dimorphic mold, have been studied in aerobically and anaerobically grown cells and in anaerobically grown cells adapting to aerobic conditions. Respiration in hyphae continues at a high level during aerobic growth but drops rapidly on exhaustion of glucose. In anaerobically grown yeastlike cells, containing no recognizable aerobic cytochromes, a small cyanide-insensitive respiration occurs. Mitochondria with well defined cristae are visible in negative contrast after KMnO
4
fixation of stringently anaerobic cells containing low amounts of fatty acid of which 10% or less are unsaturated. On aeration of anaerobically grown cells, respiratory capacity and cytochromes develop rapidly, even in the presence of 10% glucose, indicating that glucose does not repress development of respiration. However, mycelium formation by adapting yeastlike cells is repressed by high glucose concentration. In adapting cells, apparent changes in mitochondrial ultrastructure appear to be more related to changes in fixation properties of cells than to changes in the structure of mitochondria.
Separation of the Primary Dehydrogenase from the Cytochromes of the Nicotinamide Adenine Dinucleotide (Reduced Form) Oxidase of
Bacillus megaterium
Authors: Yu L. , Wolin M. J.
Published: January 2020

A selective extraction procedure was developed for sequentially extracting a fraction containing the primary dehydrogenase and a fraction containing the cytochromes of the nicotinamide adenine dinucleotide (reduced form) (NADH) oxidase of
Bacillus megaterium
KM membranes. The primary dehydrogenase (NADH-2,6-dichlorophenolindophenol oxidoreductase) activity was extracted from sonically treated membranes with 0.4% sodium deoxycholate for 30 min at 4 C. The insoluble residue was extracted with 0.4% sodium deoxycholate in 1
m
KCl for 30 min at 25 C. A combination of the two extracts and dilution in Mg
2+
gave good recovery of the original membrane NADH oxidase activity. The primary dehydrogenase fraction contained 41% of the membrane protein, no cytochromes, flavine adenine dinucleotide as the sole acid-extractable flavine, and most of the membrane ribonucleic acid (RNA). The cytochrome-containing fraction had 16% of the membrane protein, 61% of the membrane cytochrome with the same relative amounts of cytochromes
a
and
b
as the original membrane, no acid-extractable flavine, little RNA, and no oxidoreductase activity. The oxidoreductase fraction remained soluble after removal of deoxycholate whereas the cytochrome fraction became insoluble after removal of deoxycholate-KCl, but the precipitated fraction could be redissolved in 0.4% sodium deoxycholate. Treatment of both fractions with ribonuclease to destroy all of the RNA present did not affect the ability of the fractions to recombine into a functional oxidase unit. Treatment of either fraction with phospholipase A prevented restoration of a functional oxidase when the oxidoreductase and cytochrome fractions were treated in solution, but no affect on restoration of oxidase was observed when the phospholipase A treatment was carried out with the soluble oxidoreductase fraction and the insoluble cytochrome fraction.
Peptidoglycan Composition and Taxonomy of Group D, E, and H Streptococci, and
Streptococcus mutans
Authors: Slade Hutton D. , Slamp William C.
Published: January 2020

The qualitative and quantitative composition of the peptidoglycan from the cell wall of groups D, E, and H streptococci, and
Streptococcus mutans
, was determined. In group D,
S. faecalis
and the closely related species
S. liquefaciens
and
S. zymogenes
were separated from
S. faecium
and the closely related species
S. durans
on the basis of their peptidoglycan composition. A relationship among
S. bovis, S. equinus
, and some strains of
S. mutans
was indicated by the presence in each of a similar peptidoglycan containing threonine. Threonine was released from the
S. mutans
polymer as a threonine-lysine dipeptide. Hydrolysis of the dipeptide at 100 C for 24 hr in 6
n
HC1 was required to break the peptide bond. Motile group D streptococci possessed a peptidoglycan of the same composition as
S. faecium
. Group E and H strains were also similar in the composition of their peptidoglycan. The results demonstrate that peptidoglycan composition can be used to (i) aid in the division of members of an immunological group into subgroups, and (ii) indicate a relationship between members of the same genus which are not related on an immunological basis.
Isolation and Partial Chemical Characterization of the Spore Appendages of
Clostridium taeniosporum
Authors: Yolton Diane P. , Huettel Robin N. , Simpson Dianne K. , Rode L. J.
Published: January 2020

The spore appendages of
Clostridium taeniosporum
NI were removed from the spores by sonic treatment and were isolated by using discontinuous sucrose gradients. The amino acid composition of the appendages, which are elaborations of the spore coat, was similar to but not identical with the amino acid composition of the coats. Approximately 80% of the appendage dry weight was composed of 17 common amino acids, whereas 68% of the spore coat dry weight was amino acids. Mole ratios of the amino acids differed between the appendages and spore coats. The appendages contained neither diaminopimelic acid nor hydroxyproline. Glucosamine was an abundant constituent but muramic acid was absent. Approximately 10% of appendage dry weight consisted of three sugars, one of which was glucose. Phosphorus content was high and dipicolinic acid was absent. Appendage fine structure was not affected by common buffers, dilute acids and bases, hydrogen bond-breaking agents, certain proteolytic enzymes, or lysozyme.
Shape of
Treponema pallidum
Authors: Cox C. D.
Published: January 2020

Treponema pallidum
was found to be not helical, but a flat wave twisted into one to five different planes per cell.
Structural Difference Between Walls from Ends and Sides of the Rod-Shaped Bacterium
Bacillus subtilis
Authors: Fan David P. , Pelvit Mary C. , Cunningham William P.
Published: January 2020

Electron microscopy studies show that walls from ends of
Bacillus subtilis
cells are more resistant to autolytic degradation that walls from sides of the same cells. This observation suggests that these two parts of the cell are structurally different. A method is available for the isolation of walls from ends of cells.
Characterization of Colicin Ia and Colicin Ib: Antigenic Homology
Authors: Isaacson Richard E. , Konisky Jordan
Published: January 2020

Immunological techniques have been employed to determine antigenic homology between colicin Ia and colicin Ib. Results of these experiments demonstrate that the two colicins are antigenically similar.