bluuebunny/crossref_metadata_2025 huggingface dataset:
Carbon Dioxide Fixation by Cells of
Streptococcus faecalis
var.
liquefaciens
Authors: Goff Ralph C. , Hartman Ronald E.
Published: January 2020

Fixation of NaH
14
CO
3
by a heavy cell suspension of
Streptococcus faecalis
var.
liquefaciens
was studied. Several nutrients, pyridoxal, riboflavine, adenine, uracil, and O
2
stimulated
14
CO
2
incorporation into cells only under conditions that were adequate for synthesis of cell macromolecules. Biotin increased CO
2
incorporation in the absence of extensive synthesis of macromolecules, whereas O
2
inhibited incorporation under these conditions. When
14
CO
2
fixation was occurring during synthesis of macromolecules, 71% of the
14
C was incorporated into cells and 29% occurred extracellularly. Ninety-three per cent of the cellular
14
C was in protein and 5.5% was in nucleic acid. Aspartic acid was the only amino acid in the protein fraction that was radioactive. Eighty-three per cent of the extracellular
14
C was resistant to precipitation by trichloroacetic acid. When
14
CO
2
fixation was occurring in cells that were not carrying on extensive synthesis of macromolecules, 38% of the
14
C was incorporated into cells and 59% occurred in the supernatant fluid. Sixty-nine per cent of the cellular
14
C was in protein, 21% was in low-molecular-weight compounds, and 9% was in nucleic acid. Addition of unlabeled aspartate to the medium inhibited incorporation of
14
CO
2
. Based on studies of the rate of
14
CO
2
fixation, the cells fix CO
2
into a pool of intermediates which are either used for synthesis, primarily protein, or are excreted into the medium.
Specific Labeling and Physical Characterization of R-Factor Deoxyribonucleic Acid in
Escherichia coli
Authors: Silver Richard P. , Falkow Stanley
Published: January 2020

The molecular nature of R-factor deoxyribonucleic acid (DNA) was examined in
Escherichia coli
by using a method for the specific labeling of the derepressed R factor, R1, in a female cell after conjugation. Sixty minutes after mating, the R factor was isolated as a single molecule with a molecular weight of 65 × 10
6
daltons. This single molecular species sedimented as either a covalently closed molecule or a “nicked” circle. When the single R-factor component was centrifuged in a CsCl density gradient, only a single homogeneous species with a buoyant density of 1.711 g/cm
3
was observed. R-factor DNA was also isolated directly from exponentially growing cells of
E. coli
as a covalently closed single molecular species comprising about 1% of the total cellular DNA. Previous studies in
Proteus
show that R1 factor DNA components of buoyant density 1.709, 1.711, and 1.716 g/cm
3
can be identified as distinct replicons. It is suggested that the single molecule of R1 observed in
E. coli
is most simply explained as a composite structure resulting from a recombinational assemblage of a 1.709 and 1.716 g/cm
3
replicon.
Ultrastructure of Deoxyribonucleic Acid-Membrane Associations in
Escherichia coli
Authors: Altenburg B. C. , Suit Joan C. , Brinkley B. R.
Published: January 2020

Areas of contact between deoxyribonucleic acid (DNA) and intracytoplasmic membrane are frequently seen in the “extra” membrane-forming strain
Escherichia coli
0111a
1
. By examination of serial sections, it has been estimated that these DNA-membrane associations occur in at least 60% of the extra membrane-containing cells. Most of the DNA masses contained only one contact area. Several cells in which the DNA had been stretched revealed individual fibers connecting to the membrane, suggesting a firm attachment of DNA to membrane. The areas of membrane associated with DNA fibers were usually between 100 and 500 nm in diameter, although some smaller areas were seen. Electron microscopic autoradiography of cells in which the replication forks were labeled showed grains over 24% of the profiles containing a contact area, whereas there were grains over only 16% of the profiles without a contact area. Data from autoradiographs of cells in which the label was “chased” away from the replication fork showed the reverse labeling pattern. These data indicate that the areas of contact between DNA and intracytoplasmic membranes seen in electron micrographs contain the DNA replication forks.
Cytochemical Localization of Catalase Activity in Yeast Peroxisomes
Authors: Hoffmann H.-P. , Szabo A. , Avers C. J.
Published: January 2020

Diaminobenzidine oxidation product occurred in peroxisomes and in the intracristate spaces of mitochondria. The reaction was inhibited only in peroxisomes when 3-amino-1,2,4-triazole was present, but cyanide and azide inhibited deposition in both kinds of organelles.
Mutagenic Action of
N
-Methyl-
N
′-Nitro-
N
-Nitrosoguanidine on
Gaffkya tibisci
at Alkaline
p
H
Authors: Dražić Mensura , Delić Vladimir
Published: January 2020

Good yields of mutants were obtained by incubating cells of
Gaffkya tibisci
with
N
-methyl-
N
′-nitro-
N
-nitrosoguanidine in alkaline buffer. Nearly 50% of the survivors were auxotrophic mutants under the conditions described.
Mode of Action of 2-Nitro-1-Butyl Pyridinium Sulfate
Authors: Seale Ron , Weber Darrell J.
Published: January 2020

Ten micrograms of 2-nitro-1-butyl pyridinium sulfate (NBPS) per milliliter inhibited the growth of
Bacillus subtilis
by blocking thymidylate synthetase. The inhibition could be reversed by the addition of thymine or cytosine.
Host-Induced Modification/Restriction and the Utilization of 5-Bromouracil by Thymineless Mutants ofEscherichia coli
Authors: Matney Thomas S. , MacDougall Nora L. T. , Butler Mary Ann , Suit Joan C.
Published: January 2020

An mk−rk−mutation exerted no measurable effect on 5-bromouracil incorporation by a thymineless derivative ofEscherichia coliK.
Substrate Inhibition of Transglucosyl-Amylase by Maltose
Authors: Nakamura L. K.
Published: January 2020

Transglucosyl-amylase was inhibited by maltose when maltose served as a substrate. As a function of substrate concentration, the rates initially rose proportionately with increases of maltose levels until a maximal rate was attained. Further increases of maltose concentration decreased reaction rates. The attainment of a maximal rate with increasing substrate concentration and close correspondence between experimental and calculated rates indicated the involvement of ternary complex formation. Evidence also suggested that substrate inhibition is caused by maltose competing with water for the acceptor sites during complex formation.
Heterogenomic Recombinants from Compatible Nocardiae
Authors: Brownell George H. , Walsh Richard S.
Published: January 2020

Recombinants obtained from matings of
Nocardia erythropolis
×
N. canicruria
were tested for their genetic stability by comparing phenotypes from direct selection with the same population after unselected growth. Contraselective loci were employed in various combinations in order that all of the mapped characters might be subjected to unselected analysis. Some recombinant class types appeared as stable haploids, whereas others behaved as heterozygous diploids, segregating out new phenotypes. All regions of the parental genomes were found to be involved in segregation, implying that the entire mapped region can become merozygotic under standard mating conditions. On the basis of segregating phenotypes, the genetic potentials of these compatible nocardiae were ascertained as follows: the formation of a diploid with subsequent segregation of parental or haploid recombinant genomes or both; persistence of the diploid through many generations; continuing reassortment of genetic information by multiple matings between parental or recombinant organisms; and, very probably, second-round recombinations within the diploid. A considerable difference in the nuclear division time between the parental organisms was postulated to have significant effects on the nature of the unselected segregants.
Isolation and Characterization of Thymineless Mutants from Ultraviolet-Sensitive
Bacillus subtilis
Strains
Authors: Felkner Ira C.
Published: January 2020

Thymineless mutants of
Bacillus subtilis
168
ind, hcr-9
were isolated by using trimethoprim. These and other Thy
−
strains differed drastically from Thy
+
ones in their patterns of [
3
H]thymidine uptake and growth in trimethoprim-containing medium. Transformation was negligible between most mutants derived from the ultraviolet-sensitive strain 168
ind, hcr-9
but significant between 168
ind, thy
and these mutants. The latter and these new mutants all grow in the presence of trimethoprim plus thymidine or thymine and fail to grow if thymine or thymidine is omitted.
Cation Transport in
Serratia marcescens
and
Serratia marinorubra
Authors: Gale Nord L. , Dittman June B. , Goldner Bernard H.
Published: January 2020

The sodium, potassium, and magnesium ion contents of
Serratia marcescens
and those of its salt-tolerant relative,
S. marinoruba
, were determined by atomic-absorption spectrometry. The intracellular K
+
and Mg
2+
contents of both microorganisms were found to be dependent on the ionic strength of the growth or suspending medium. The Mg
2+
content of
S. marinoruba
was generally greater than that of
S. marcescens
. The Na
+
content of the cells was normally low and did not increase as the cells aged or when the cells were grown in media of high ionic strength. The transport of K
+
by resting cells suspended in hypertonic solution was studied by chemical and light-scattering techniques and was found to be more rapid in
S. marcescens
than in
S. marinorubra
. The slower rate of K
+
transport in
S. marinorubra
is probably related to the lower glycogen reserves found in resting cells of this microorganism. K
+
transport was found to have a
p
H optimum of 5.5 to 6.1 for
S. marcescens
, and the
K
m
for K
+
was approximately 1.6 m
m
. Na
+
and Mg
2+
were not taken up by the cells, although the presence of Mg
2+
tended to decrease rates of K
+
uptake. Tris-(hydroxymethyl)aminomethane, routinely used for resuspending the cells, was apparently taken up by the cells at
p
H >7.
Uptake of Synthetic Polynucleotides by Competent Cells of
Bacillus subtilis
Authors: Ciferri Orio , Barlati Sergio , Lederberg Joshua
Published: January 2020

A survey was made of the capacity of competent cells of
Bacillus subtilis
to take up synthetic polynucleotides. Polydeoxyribonucleotides but not polyribonucleotides are taken up by the cells. Both types of polynucleotide failed to compete with transforming deoxyribonucleic acid in the transformation assay whereas both stimulated amino acid incorporation. The latter phenomenon appears to be nonspecific as there is no correlation between the codon composition of the polynucleotides employed and the amino acids whose incorporation was stimulated.
Lipids of a Sterol-Nonrequiring Mycoplasma
Authors: Plackett P. , Smith P. F. , Mayberry W. R.
Published: January 2020

The lipids of the sterol nonrequiring
Mycoplasma
strain S743 were found to include both ester glycerophosphatides (phosphatidylglycerol, acylphosphatidylglycerol, and diphosphatidylglycerol) and ceramide glycerophosphate compounds containing
N
-hydroxyacyl groups. The major phosphosphingolipid was tentatively identified as a hydroxyceramidephosphorylglycerol containing an
O
-acyl group. These compounds became labeled during growth in the presence of
32
P-orthophosphate,
14
C-glycerol, or
14
C-palmitate. The lipid fraction also contained free long-chain base.
14
C-palmitate was converted to labeled sphinganine. The long-chain base composition of the lipids was modified by growing the organisms in media containing different fatty acids, which were converted to bases containing two more C atoms per molecule. Ninety per cent of the long-chain base from cells grown in medium supplemented with elaidate consisted of monounsaturated C
20
base.
Isolation and Preliminary Characterization of Developmental Mutants from
Microsporum gypseum
Authors: Leighton T. J. , Stock J. J.
Published: January 2020

Developmental mutants affected in either sporulation or spore germination have been isolated from
Microsporum gypseum
with the aid of nitrosoguanidine or as spontaneously occurring mutants. The time course levels of several proteins temporally associated with conidial development have been assayed in the wild-type and mutant strains. The spore germination characteristics of two of the mutants are described. The relationship of alkaline protease accumulation to tyrosinase accumulation and spore germination is discussed.
Association of the
Bacillus subtilis
Chromosome with the Cell Membrane: Resolution of Free and Bound Deoxyribonucleic Acid on Renografin Gradients
Authors: Ivarie Robert D. , Pène Jacques J.
Published: January 2020

Linear density gradients of Renografin have resolved two components of bacterial deoxyribonucleic acid (DNA) in sheared lysates. Component 1, at equilibrium density after 5 hr of centrifugation, is enriched for newly synthesized DNA and markers near the origin and terminus of replication. It contains 5% of total cellular protein, 25% of the phospholipids, 30 to 50% of the DNA, 4 to 11% of unstable ribonucleic acid (RNA), RNA polymerase, and low amounts of DNA polymerase. The material is sensitive to Pronase and Sarkosyl. In unsheared lysates, all of the DNA forms a band at this position. Shearing the lysate generates a slow-sedimenting fraction of DNA (component 2) which contains more uniformly labeled than newly synthesized DNA. These observations suggest that replicating DNA and DNA at the origin and possibly the terminus of replication are associated with membrane. The amount of uniformly labeled DNA in component 1 and an estimate of the number of chromosomal fragments suggest that other parts of the chromosome are possibly associated with the membrane.
Neutral Amino Acid Transport in
Pseudomonas fluorescens
Authors: Hechtman P. , Scriver C. R.
Published: January 2020

Membrane transport of β-alanine,
l
-alanine, and
l
-proline was studied in a β-alanine transaminaseless mutant (strain 67) of
Pseudomonas fluorescens
. In this mutant β-alanine is metabolically inert, and it was therefore possible to demonstrate active transport of this substrate in the absence of intracellular catabolism. The permease which catalyzes the uptake of β-alanine also transports
l
-proline and
l
-alanine. This common transport system was distinguished from permeases which transport only
l
-alanine and only
l
-proline by competition studies in strain 67 and by studies of transport specificity in a permeaseless mutant (strain 67/4MTR).
Genetic and Molecular Characteristics of X-Ray-Sensitive Mutants of
Escherichia coli
Defective in Repair Synthesis
Authors: Kato Takesi , Kondo Sohei
Published: January 2020

Alleles responsible for X-ray-sensitive characteristics of three mutants of
Escherichia coli
B, which were also sensitive to ultraviolet (UV) irradiation, were mapped near
metE
locus, and named
res-1, res-2
, and
res-3
. All the
res
−
mutants showed no host cell reactivability (Hcr
−
) for transducing deoxyribonucleic acid (DNA) of P1 phage irradiated by UV but they were Hcr
+
for infective DNA of P1 phage. Furthermore, they showed no detectable activity of DNA polymerase. Characteristics of allele
res-1
were studied in detail. The mutant
res-1 uvr
+
showed an extensive degradation of DNA after UV irradiation. Double mutants carrying
res-1 uvrA
−
,
res-1 uvrB
−
, and
res-1 uvrC
−
showed no marked increase in UV sensitivity beyond that of the
uvr
−
single mutants and only negligible UV-induced DNA degradation. The
uvr
−
mutations showed no such suppressive effect on DNA degradation induced by X rays in these double mutants. It is concluded that
res
−
mutants are defective in the second step (repair synthesis) of the excision repair process and that DNA polymerase is partly responsible for the assumed resynthesis step.
Metabolism of Phosphatidylglycerol and Lysyl Phosphatidylglycerol in
Staphylococcus aureus
Authors: Gould Robert M. , Lennarz W. J.
Published: January 2020

The metabolism of phosphatidylglycerol and lysyl phosphatidylglycerol was studied in
Staphylococcus aureus
under four conditions: growing at
p
H 7.0 and 5.2, and not growing (resting) at
p
H 7.0 and 5.2. Measurements of the amounts of phosphatidylglycerol and lysyl phosphatidylglycerol, as well as labeling and pulsechase experiments, revealed that the phosphate group of the former and the lysyl group of the latter were in a state of active turnover. A marked decline in the cellular level of phosphatidylglycerol observed when cells were resting at
p
H 5.2 was found to be caused by both a decrease in synthesis and an increase in catabolism. The level of lysyl phosphatidylglycerol was found to be relatively constant under the four incubation conditions, although the lysyl moiety was in a state of turnover. Experiments designed to test the possible role of lysyl phosphatidylglycerol as a lysyl group donor in biosynthetic processes or in lysine transport were negative; no evidence to support the hypothesis that lysyl phosphatidylglycerol serves as an intermediate was obtained.
Cell Wall Synthesis byChlamydia psittaciGrowing in L Cells
Authors: Tribby Ilse I. E.
Published: January 2020

Biochemical events accompanying changes in structure and behavior of the cell walls ofChlamydia psittacistrain 6BC during its developmental cycle in L cells (mouse fibroblasts) were studied by measuring at short intervals the effect ofd-cycloserine and penicillin G on incorporation of labeled intermediates into acid-insoluble fractions of infected L cells in which host incorporation had been inhibited by cycloheximide and into intact chlamydial cells and cell walls separated from the infected L cells.d-Cycloserine enhanced the incorporation of14C-l-alanine at all times in the developmental cycle, but the incorporation of14C-l-lysine was always inhibited. In parallel experiments, penicillin G had no effect on incorporation of any of these intermediates, but when infected L cells incorporated14C-l-alanine in the presence of penicillin G, the labeled alanine was released more rapidly in the subsequent absence of the antibiotic than in its continued presence. When either penicillin G ord-cycloserine was present throughout the developmental cycle,C. psittacicontinued to synthesize deoxyribonucleic acid and protein, but at less than normal rates.
Alterations of the L-Forms of a Sporebearing Bacillus
Authors: Dienes Louis
Published: January 2020

A large pleomorphic gram-negative bacillus developed as a contaminant on blood-agar. Spores were formed in one culture. L-forms were produced with penicillin on blood-agar with 2.5% NaCl; they grew well when transplanted to agar with 0.5% NaCl. After several transplants and long incubation of the L-forms without penicillin, in three transplants small gram-negative pleomorphic bacilli grew, but no L-forms. This occurred once on blood-agar and twice on 30% gelatin. The growth obtained from these small bacilli was similar in morphology and in the physical properties of the organisms to the altered L-forms of
Proteus
and
Salmonella
. Multiplication of the pleomorphic organisms and development of branching filaments from the round forms was apparent. The original large gram-negative bacillus was regularly recovered from the L-forms, and was recovered several times from the descendants of the small bacilli. These observations are essentially similar to those made with L-forms of
Proteus
and with an L-form studied in 1952, indicating alterations in L-forms of bacteria which do not produce B type L-forms.
Effect of Selenomethionine on Growth of
Escherichia coli
and
Bacillus megaterium
Authors: Wu M. , Wachsman J. T.
Published: January 2020

Studies with methionineless strains of
Escherichia coli
WWU and
Bacillus megaterium
KM have shown that selenomethionine only partially satisfies their methionine requirement.
Induction of Nonpigmented Variants of
Erwinia herbicola
by Incubation at Supraoptimal Temperatures
Authors: Chatterjee A. K. , Gibbins L. N.
Published: January 2020

Several strains of
Erwinia herbicola
produce white variants at high frequency when grown in yeast beef broth at 37 C. The relationships of the variants of
E. herbicola
Y46 to the parent strain have been studied with respect to cultural, morphological, physiological and serological features. All the white variants are auxotrophic, showing a requirement for thiamine, and no instance of reversion was observed. Representative variants show reactions similar to the parent strain on treatment with both virulent and temperate phages. Possible mechanisms by which the variants could arise are indicated.
Glycerol-Specific Revertants of a Phosphoenolpyruvate Phosphotransferase Mutant: Suppression by the Desensitization of Glycerol Kinase to Feedback Inhibition
Authors: Berman Myra , Lin E. C. C.
Published: January 2020

Glycerol-specific revertants were isolated from a phosphoenolpyruvate phosphotransferase mutant lacking enzyme I activity. Sixteen of the eighteen separately derived revertants were found to synthesize a fully active glycerol kinase no longer subject to feedback inhibition by fructose 1,6-diphosphate. The suppressor mutation mapped at the known
glpK
locus. When the fructose, 1,6-diphosphate-insensitive kinase allele was transduced into a strain producing the
glp
enzymes constitutively, cells of the resultant strain were susceptible to killing by glycerol if this compound was added to a culture growing exponentially in casein hydrolysate. This phenomenon had been previously described for a strain which had a constitutive glycerol kinase refractory to feedback inhibition, but isolated by a different procedure. It is suggested that the suppression of the growth defect on glycerol in the enzyme I
−
mutant by the fructose 1,6-diphosphate-insensitive kinase is achieved by increasing the in vivo catalytic potential of glycerol kinase. This increased activity would allow more rapid conversion of glycerol to
l
-α-glycerophosphate, the true inducer of the
glp
system. The enzyme I defect in the parental strain impaired the inducibility of the
glp
system so that the normal basal catalytic activity of the kinase was insufficient to insure induction by glycerol.
Bacteriolysis and Inhibition of Gram-Positive Bacteria by Components of
Streptococcus zymogenes
Lysin
Authors: Jackson Robert W.
Published: January 2020

The ability of the A and L components of
Streptococcus zymogenes
lysin to cause lysis or to inhibit growth of a variety of gram-positive bacteria has been examined. Frank lysis of some, but not all, strains of
S. faecalis, S. faecium
, and
S. liquefaciens
by L component alone was demonstrated. None of the strains of these species was lysed by A component alone.
S. durans
was not lysed by either component. Inhibition of growth of all enterococcal strains by both A substance-producing and L substance-producing mutants of
S. zymogenes
was also demonstrated. However, inhibition by the A substance producer was markedly less than by the L substance producer. Inhibition of the growth of a number of other gram-positive genera by both A and L mutants was also noted.
Sterol Requirements of T-Strain Mycoplasmas
Authors: Rottem S. , Pfendt E. A. , Hayflick L.
Published: January 2020

T-strain mycoplasmas are very sensitive to digitonin, amphotericin B, and progesterone. This sensitivity and the relatively high content of cholesterol found in the cells indicated a possible requirement of T-strain mycoplasmas for sterols. This suspected requirement was demonstrated directly in a lipid-poor medium and can be met by cholesterol, as well as by β-sitosterol and to a lesser degree by 7-dehydrocholesterol, cholestanol, stigmasterol, and ergosterol but not by cholesterol laurate or cholestan-3-one. Coprostanol, epicoprostanol, and epicholestanol inhibited cell growth. This inhibition could be partially reversed by increasing the cholesterol concentration in the growth medium. Because of their sterol requirement and their unique requirement for urea, T-strain mycoplasmas might be classified as the third genus in the order
Mycoplasmatales
.
Taxonomic Implications of Spore Fine Structure in
Clostridium bifermentans
Authors: Rode L. J. , Smith Louis Ds
Published: January 2020

Thirty-five strains of
Clostridium bifermentans
were, in most part, culturally homogeneous by conventional taxonomic criteria but were heterogeneous with respect to spore fine structure. Fourteen of the strains produced spores with appendages, distributed among four distinct ultrastructural types. No consistent correlation existed between spore type and other variable properties of these strains. It is proposed, therefore, that these spore appendage-type strains be considered as “varieties” of
C. bifermentans
and that they should not be designated as new species.
Electron Microscopic Observations on the Structure of
Treponema zuelzerae
and Its Axial Filaments
Authors: Bharier M. A. , Eiserling F. A. , Rittenberg S. C.
Published: January 2020

The fine structure of the spirochete
Treponema zuelzerae
, and particularly of its axial filaments, was investigated by using the electron microscope. The cell consists of a protoplasmic core surrounded by two concentric envelopes, each approximately 12 nm in width. Between these envelopes are two axial filaments, one originating at each pole of the cell, which overlap and lie side by side in the central region of the cell. The diameter of the axial filaments is 18.0 to 18.5 nm. The terminal region of each filament at its proximal end consists of a hook-like structure, very similar in appearance to the proximal end of a bacterial flagellum. The outer envelope of the cell is readily disrupted with distilled water, and this treatment often results in the release of the filaments from their axial position. A sheath is seen surrounding the filaments when cells are treated with distilled water for no more than 1 min and fixed immediately with osmium tetroxide or glutaraldehyde. This sheath has a striated fine structure and a diameter of 46 nm.
Bacillus thuringiensis
Sporulation at Suboptimal Temperature
Authors: Aronson John N. , Thompson Faith M.
Published: January 2020

Bacillus thuringiensis
var.
thuringiensis
Berliner grown at 14 C on a chemically defined liquid medium slowly produced spores and parasporal inclusions. Sporulation ultimately attained 50 to 100% of that of cultures grown at 30 C.
Biochemical and Genetic Characterization of a Temperature-Sensitive, Tryptophanyl-Transfer Ribonucleic Acid Synthetase Mutant of
Bacillus subtilis
Authors: Steinberg William , Anagnostopoulos C.
Published: January 2020

A temperature-sensitive, 5-fluorotryptophan (5FT)-resistant mutant of
Bacillus subtilis
was isolated which forms an altered tryptophanyl transfer ribonucleic acid synthetase [
l
-tryptophan: sRNA ligase (AMP), EC 6.1.1.2]. The mutant grows well at 30 C but not at 42 C. At the latter temperature, protein and ribonucleic acid (RNA) synthesis are abolished while deoxyribonucleic acid (DNA) synthesis proceeds for a considerable time. Tryptophanyl-transfer RNA (tRNA) synthetase activity is not detectable in the extracts of the mutant grown at 30 C whether this activity is measured by the attachment of
l
-tryptophan to tRNA or the
l
-tryptophan-dependent exchange of
32
P-pyrophosphate with adenosine triphosphate. Mixing experiments with extracts from the wild type and the mutant have ruled out the presence of an inhibitor or the absence of an activator as possible causes. Attempts to retrieve enzyme activity in vitro by various means (different conditions for cell disruption, addition of
l
-tryptophan, and adenosine triphosphate to the extraction buffer containing glycerol) were unsuccessful. The mutation in the locus of the tryptophanyl tRNA synthetase (
trpS
) was mapped on the bacterial chromosome by transformation and transduction. It is located between
argC
and
metA
. All temperature-resistant transformants recover wild-type levels of tryptophanyl tRNA synthetase activity and sensitivity to 5FT. Spontaneous revertants to temperature resistance are 5FT sensitive, but their levels of tryptophanyl tRNA synthetase activity and the thermolability of this enzyme in cell-free extracts varies. These revertants do not support the growth of a presumed nonsense mutant of phase SPO-1. Transduction experiments with phage PBS-1 indicated that reversion must be the result of an event at the site of the original mutation or at a site extremely close to it.
Park-Williams Number 8 Strain ofCorynebacterium diphtheriae
Authors: Lampidis Theodore , Barksdale Lane
Published: January 2020

Five clones of the Park-Williams number 8 strain ofCorynebacterium diphtheriae, previously maintained in separate laboratories, were examined for their colonial and biochemical properties, for the restriction and modification system which operates to obscure their lysogeny, and for their capacity to produce large amounts of toxin under ordinary laboratory conditions. The phenotypes of their phage, P, produced in strain 603 and C7 (P·603 and P·C7) differ both as to stability to storage in the cold and to inactivation by antiphage serum. Evidence for a high degree of stability in the integration of P prophage in the PW8 genome is presented.
Function of Ubiquinone in Electron Transport from Reduced Nicotinamide Adenine Dinucleotide to Nitrate and Oxygen in
Aerobacter aerogenes
Authors: Knook D. L. , Planta R. J.
Published: January 2020

The possible role of quinones in the electron transport system of
Aerobacter aerogenes
was investigated. The only quinone found in measurable amounts in bacteria grown in minimal media under both aerobic and anaerobic conditions was ubiquinone-8. Membrane-bound ubiquinone-8 could be removed by extraction with pentane, or destroyed by ultraviolet irradiation, with a concomitant loss of both reduced nicotinamide adenine dinucleotide (NADH) oxidase and NADH-linked respiratory nitrate reductase activity. In the extracted membrane preparations, these enzymatic activities could be restored, both to the same degree, by incorporation of ubiquinone-6, -8, or -10, but not by incorporation of menaquinones. The NADH oxidation and the nitrate reduction were sensitive to the respiratory inhibitors dicoumarol, lapachol, and cyanide. The results obtained indicate that ubiquinone-8 mediates the electron transport between NADH and oxygen as well as between NADH and nitrate. Branching of the electron transport chain to oxygen and nitrate occurs after an initial common pathway.
Microcalorimetric Determination of the Affinity of
Saccharomyces cerevisiae
for Some Carbohydrate Growth Substrates
Authors: Murgier M. , Belaich J. P.
Published: January 2020

A microcalorimetric method using a Tian-Calvet apparatus was utilized for measuring the
K
m
and
V
max
of intact yeast cells for some carbohydrate substrates. These values were obtained for fructose, galactose, and maltose. The heats of ethanolic fermentations were also directly determined, and the results were very close to those obtained by using theoretical calculations and standard values.
Mode of Action of Streptozotocin
Authors: Reusser Fritz
Published: January 2020

Streptozotocin induces rapid degradation of deoxyribonucleic acid (DNA) in actively dividing or resting
Bacillus subtilis
cells. Difference spectroscopy showed that the antibiotic interacts specifically with cytosine containing mononucleotides in vitro. This interference occurs only within the very narrow
p
H range of 5 to 5.5 and is reversed immediately upon lowering or increasing the
p
H. No measurable interaction was observed between isolated DNA and streptozotocin. The possibility is discussed that interaction of streptozotocin with cytosine residues in cellular DNA, although possibly taking place at a very low frequency, may constitute the primary step inducing DNA strand breakage.
Fine Structure of
Rickettsia canada
in Tissues of
Dermacentor andersoni
Stiles
Authors: Brinton Lyle P. , Burgdorfer Willy
Published: January 2020

Preliminary observations on growth and developmental fine structure of
Rickettsia canada
in various organs and tissues of the hard tick,
Dermacentor andersoni
Stiles, are reported.
R. canada
is typically rod-shaped, being delimited with a three-layered wall having a velvety coating adsorbed to its exterior surface. A finely reticulated cytoplasmic matrix containing prominent ribosomes is delimited with a three-layered unit membrane. Average length and width of these organisms are 1.6 by 0.4 μm. Although
R. canada
produces a generalized infection in
D. andersoni
, hypodermal and muscle tissues experience heaviest growth. Three morphologically distinct rickettsial forms were observed in individual hypodermal cells: (i) typical growth forms with a finely reticulated cytoplasmic matrix and distinct ribosomes; (ii) atypical forms with lightly to densely staining cytoplasm and a coagulated appearance in which ribosomes cannot be distinguished from the matrix; and (iii) forms with crystalline bodies that have a striated to beaded lattice structure and, at times, a fibrillar body in the cytoplasm as well. Occasional finger-like to irregular invaginations of the plasma membrane are noted. Intranuclear growth was demonstrated by electron microscopy in gut epithelial cells only. Growth and development of
R. canada
were manifest in all tissues examined.
Selenomethionine, a Methyl Donor for Bacterial Nucleic Acids
Authors: Wu M. , Wachsman J. T.
Published: January 2020

dl
-Selenomethionine is as efficient a methyl donor for nucleic acid methylation in both
Bacillus megaterium
KM and
Escherichia coli
WWU as
dl
-methionine.
Influence of Thymine Starvation on the Integrity of Deoxyribonucleic Acid in
Escherichia coli
Authors: Baker Max L. , Hewitt Roger R.
Published: January 2020

The influence of thymine starvation on the single-strand molecular weight of deoxyribonucleic acid (DNA) from
Escherichia coli
was determined by sedimentation through gradients of alkaline sucrose. Growth of cells for as long as 150 min in thymineless medium did not significantly reduce the molecular weight below the control value of 2.4 ± 0.3 × 10
8
daltons. Incubation of cells in thymineless medium after exposure to 500 ergs/mm
2
of ultraviolet light or 20 krad of
137
Cs gamma rays did not appear to block the rejoining of single-strand breaks associated with irradiation. Thus, DNA repair enzymes, presumably including DNA ligase, are not significantly inhibited by thymine starvation.
Characterization of the Reduced Nicotinamide Adenine Dinucleotide Phosphate-Nitrate Reductase of
Aspergillus nidulans
Authors: Downey R. J.
Published: January 2020

The reduced nicotinamide adenine dinucleotide phosphate (NADPH)-nitrate oxidoreductase (EC 1.6.6.2) from
Aspergillus nidulans
was purified over 200-fold by use of salt fractionation, gel filtration, and ion-exchange chromatography. The purified enzyme was specific for NADPH and catalyzed reduction of nitrate, cytochrome
c
from isolated mitochondria of
Aspergillus
, and mammalian cytochrome
c
. An
S
0.725
20, w
of 7.8 was derived with sucrose density gradient centrifugation, and a Stokes radius of 6.4 nm was derived by gel filtration on Sephadex G-200. From these values, a molecular weight of 197,000 was computed, assuming
¯v
= 0.725 cm
3
/g. The spectral properties of the purified enzyme suggested a flavine component was present but revealed no pattern indicative of a hemoprotein. A cytochrome
c
, similar to the cytochrome
c
from isolated mitochondria, was found unassociated with the nitrate reductase after ion-exchange chromatography. No NADPH-nitrate reductase activity was detected in isolated mitochondria. Spectrally discernable reduction of the flavine component of the enzyme at 450 nm was noted after reaction with NADPH. This reduction was inhibited by
p
-chloromercuribenzoate but not by KCN. The addition of nitrate to NADPH reduced enzyme caused a reoxidation of the flavine component via a reaction which was inhibited by KCN but not by
p
-chloromercuribenzoate. The half-life of the purified enzyme at 37 C was 20 min for NADPH-nitrate reductase and 35 min for NADPH-cytochrome
c
reductase.
Division Cycle of
Myxococcus xanthus
II. Kinetics of Stable and Unstable Ribonucleic Acid Synthesis
Authors: Zusman David , Rosenberg Eugene
Published: January 2020

The kinetics of stable and unstable ribonucleic acid (RNA) synthesis during the division cycle of
Myxococcus xanthus
growing in a defined medium was determined. Under these conditions,
M. xanthus
contains one chromosome which is replicated during 80% of the cell cycle. Stable RNA synthesis was measured by pulselabeling an exponential-phase culture with radioactive uridine and then preparing the cells for quantitative autoradiography. By measuring the size of individual cells as well as the number of grains, the rate of stable RNA synthesis as a function of cell size was determined. Unstable RNA synthesis during the division cycle was determined by correlating the data for stable RNA synthesis with the relative amounts of stable and unstable RNA labeled during the short pulse. The data reported here demonstrate that: (i) cells synthesize both stable and unstable RNA throughout the division cycle; (ii) the rate of stable RNA synthesis increases in two discrete steps, corresponding to average ages of 0.15 and 0.75 generations; (iii) the rate of unstable RNA synthesis exhibits an initial rise, followed by a relatively constant rate of synthesis, and finally, a burst of unstable RNA synthesis prior to septum formation. The half-life of unstable RNA of
M. xanthus
, generation time of 390 min at 30 C, was 4 min. Comparison of the rates of stable and unstable RNA synthesis indicates noncoordinate RNA synthesis within the normal division cycle.
Isolation, Culture, and Fermentation Characteristics of
Selenomonas ruminantium
var.
bryanti
var. n. from the Rumen of Sheep
Authors: Prins R. A.
Published: January 2020

Large forms of
Selenomonas
sp. were isolated from the sheep rumen on a rumen fluid-glucose-agar medium by using a differential centrifugation technique to purify the inoculum. The cells from the six isolated strains were curved, gram-negative, strictly anaerobic crescents, and rapidly motile by flagella attached to the concave side of the cell. One or more of the volatile fatty acids were essential for growth. None of the strains produced indole or reduced nitrate. All strains grew on fructose, glucose, mannose, cellobiose, maltose, sucrose, and salicin. Fermentation end products from glucose were mainly lactate, acetate, propionate, and formate. Small amounts of succinate were formed. The final
p
H in a glucose medium ranged between 4.3 and 4.5. On the basis of the sugar fermentation characteristics and the capacity to form hydrogen sulfide from cysteine, it is suggested that one of the strains is a large form of
Selenomonas ruminantium
. The other five strains are designated
S. ruminantium
var.
bryanti
, var. n.
Isolation and Properties of a New Species of Ribonucleic Acid Synthesized in Sporulating Cells of
Saccharomyces cerevisiae
Authors: Kadowaki Kiyoshi , Halvorson H. O.
Published: January 2020

A new species of ribonucleic acid (RNA) was detected in sporulating culture of
Saccharomyces cerevisiae
. This RNA was isolated by sucrose density gradient centrifugation and polyacrylamide gel electrophoresis and partially characterized. It has a sedimentation coefficient of approximately 20
S
and a nucleotide composition distinct from other known RNA species in yeast, and it hybridizes with nuclear but not with mitochondrial deoxyribonucleic acid.
Repair of Irradiated Transforming Deoxyribonucleic Acid in Wild Type and a Radiation-Sensitive Mutant of
Micrococcus radiodurans
Authors: Moseley B. E. B. , Mattingly Alice
Published: January 2020

The survival of biological activity in irradiated transforming deoxyribonucleic acid (DNA) has been assayed in the wild type and a radiation-sensitive mutant of
Micrococcus radiodurans
. The frequency of transformation with unirradiated DNA was lower in the mutant to about the same extent as the mutant's increased sensitivity to radiation. However, in both the wild type and the mutant, the irradiated DNA that was incorporated into the bacterial genome was repaired to the same extent as determined by the loss of transforming activity with increasing radiation dose. This applied to DNA irradiated either with ionizing or ultraviolet (UV) radiation. The rate of inactivation of biological activity after UV radiation was the same in any of the DNA preparations tested. For ionizing radiation, the rate of inactivation varied up to 40-fold, depending on the DNA preparation used, but for any one preparation was the same whether assayed in the wild type or the radiation-sensitive mutant. When recipient bacteria were irradiated with ionizing or UV radiation immediately before transformation, the frequency of transformation with unirradiated DNA fell, rapidly and exponentially in the case of the sensitive mutant but in a more complicated fashion in the wild type. The repair of DNA irradiated with ionizing radiation was approximately the same whether assayed in unirradiated or irradiated hosts. Thus, irradiation of the host reduced the integration of DNA but not its repair.
Lysine Suppressor in
Escherichia coli
Authors: Kaplan S.
Published: January 2020

Head amber mutant of phage T4D was used to determine the efficiency of suppression and the amino acid inserted by
Escherichia coli
CA273 (
sup-273
formerly Su
+
β
). The level of suppression determined was 8%, and the amino acid inserted was shown to be lysine.
Pseudogermination in Dipicolinic Acid-Less Spores of a
Bacillus cereus
T Mutant
Authors: Frank Hilmer A. , Tonaki Keith I.
Published: January 2020

Dipicolinic acid-less spores of a
Bacillus cereus
T mutant in 33 m
m
sodium bicarbonate (
p
H 8.5) underwent pseudogermination (germination-like changes) accompanied by ribonucleic acid leakage and loss of viability.
Velocity of Chromosome Replication in Thymine-Requiring and Independent Strains of
Bacillus subtilis
Authors: Ephrati-Elizur Erela , Borenstein Shoshana
Published: January 2020

Chromosomes in spores of a thymineless mutant of
Bacillus subtilis
strain 168 were shown to have a replication fork, unlike chromosomes in spores of the
thy
+
strain which are in a complete form. As a consequence the number of replication forks in germinating cultures is higher in the
thy
−
strain than in the
thy
+
one. Chromosome replication time (
C
) in the
thy
+
strain was found to be about 53 min for growth rates from 20 to 60 min. In the
thy
−
strain,
C
was about 75 min at high growth rates and increased with decreasing growth rate when the thymine concentration was not limiting. With limiting thymine concentrations in the medium replication velocity decreased independently of growth rate.
Ribosomal Competence and Spore Germination in
Fusarium solani
Authors: Rado Thomas A. , Cochrane Vincent W.
Published: January 2020

Extracts prepared from macroconidia of
Fusarium solani
f. sp.
phaseoli
are capable, under defined conditions, of incorporating phenylalanine into polypeptide with exogenous polyuridylic acid as messenger. Extracts from ungerminated and germinated spores have approximately the same activity. With endogenous template, leucine incorporation occurs, but in this reaction extracts from germinated spores have about 10 times more activity than do those from ungerminated spores. It is suggested that the low rate in ungerminated spores is attributable to a relative deficiency in the number of ribosomes which are organized into polysomes.
Preferential Transcription of
Bacillus subtilis
Light Deoxyribonucleic Acid Strands During Sporulation
Authors: Yamakawa Toshio , Doi Roy H.
Published: January 2020

Messenger ribonucleic acid (RNA) from log and sporulation stages of growth were transcribed mainly from the heavy strand of the complementary strands of
Bacillus subtilis
deoxyribonucleic acid (DNA). During sporulation a slight transcription shift from heavy to light DNA strands was observed. RNA-DNA hybrid competition experiments revealed that this shift was due to sporulation-specific transcription from light-DNA strands.
Mutation of
Saccharomyces cerevisiae
Preventing Uptake of
S
-Adenosylmethionine
Authors: Spence Kemet D.
Published: January 2020

A mutant has been isolated whose aberration severely restricts the ability of cells of
Saccharomyces cerevisiae
to take up
S
-adenosylmethionine. The mutation apparently also affects adenosylhomocysteine uptake, but not that of the
S
-adenosylmethionine moieties adenine, homocysteine, homoserine, or methionine, nor the sulfonium compound,
S
-methylmethionine. It is a single, chromosomal mutation whose expression is not dependent on the presence of ammonium ions.
Comparison of the Two Isofunctional Enol-Lactone Hydrolases from
Acinetobacter calcoaceticus
Authors: Katagiri M. , Wheelis M. L.
Published: January 2020

The rates of thermal denaturation and the molecular weights of the two isofunctional enol-lactone hydrolases (ELH I and ELH II) of
Acinetobacter calcoaceticus
were determined. The molecular weights of ELH I and ELH II were found by gel filtration to be approximately 24,000 and 21,000, respectively. In crude extract at 45 C the two enzymes showed a marked difference in rate of thermal denaturation. After chromatography on Sephadex G-100, however, the rates were nearly identical. The thermolability of ELH II in crude extract was shown to be due to its sensitivity to an unidentified component of the crude extract which modified its rate of thermal denaturation. In the light of the physical similarities of the two enzymes, it is concluded that the different regulatory patterns imposed upon the two enzymes do not provide sufficient evidence that they are the product of two different structural genes.
Purification of
Bacteroides amylophilus
Protease
Authors: Lesk E. M. , Blackburn T. H.
Published: January 2020

A protease was released by
Bacteroides amylophilus
cells in late stationary phase, approximately 12 hr after maximum cell density was reached. The protease was concentrated by adsorption on diethylaminoethyl (DEAE)-Sephadex and was purified 532-fold by DEAE-Sephadex chromatography, by G-200-Sephadex gel filtration, and by isoelectric focusing. The purified protease was active between
p
H 4.5 and 12.0 with optima at
p
H 6.0 and 11.5. Evidence against there being a single protease was given by the differential inhibition of esterase and protease activities by some inhibitors. There was some evidence that only a single protease was present as the ratio of protease activity at various
p
H values did not alter significantly during purification or when the purified protease was partially heat-inactivated or treated with two specific trypsin-type protease inhibitors:
N
-α-tosyl-
l
-lysylchloromethyl ketone or phenylmethane-sulfonyl fluoride. Two forms of the same protease were found by acrylamide gel electrophoresis. Gel filtration confirmed the presence of protease in 30,000 and 60,000 molecular-weight forms. Treatment with 1 m
m
ethylenediaminetetraacetic acid or with 4
m
urea failed to convert the 60,000-molecular-weight to the 30,000-molecular-weight species.