bluuebunny/crossref_metadata_2025 huggingface dataset:
Cell Envelope of an Iron-Oxidizing Bacterium: Studies of Lipopolysaccharide and Peptidoglycan
Authors: Wang W. S. , Korcynski M. S. , Lundgren D. G.
Published: January 2020

Further structural detail is presented of the cell envelope of the chemolithotroph
Ferrobacillus ferrooxidans
(
Thiobacillus ferrooxidans
). Thin sections of purified lipopolysaccharide (LPS) and peptidoglycan show structures comparable to those seen in the envelope of intact cells, whereas negative stains of LPS appear as sheets, or ribbons, or both. The sugars common to LPS, namely, heptose, glucose, galactose, mannose, and 2-keto-3-deoxyoctulosonate, were identified. The cations, iron, calcium, and magnesium, were associated with LPS. The purified LPS had a density of 1.28 and an uncorrected sedimentation coefficient of 99.9
S
.
Genetic Control of the Secondary Modification of Deoxyribonucleic Acid in
Escherichia coli
Authors: Mamelak Linda , Boyer Herbert W.
Published: January 2020

The wild-type restriction and modification alleles of
Escherichia coli
K-12 and B were found to have no measurable effect on the patterns of methylated bases in the deoxyribonucleic acid (DNA) of these strains. The genetic region controlling the methylation of cytosine in
E. coli
K-12 was mapped close to
his
, and the presence or absence of this gene in
E. coli
B or
E. coli
K had no effect on the restriction and modification properties of these strains. Thus, only a few of the methylated bases in the DNA of these strains are involved in host modification, and the biological role of the remainder remains obscure.
Potassium Uptake During Microcyst Formation in
Myxococcus xanthus
Authors: Giberman E. , Rosenberg E.
Published: January 2020

The kinetics of
42
K uptake by
Myxococcus xanthus
during vegetative growth and microcyst formation were determined. In the medium studied, growing cells concentrated potassium about 100-fold, yielding an intracellular concentration of 147 m
m
. The influx of K
+
in growing cells was 17 ± 3 pmoles of K
+
/cm
2
min. About 5 hr after induction of vegetative cells to microcysts, the K
+
influx decreased and the intracellular concentration fell. By 18 hr after induction, there was no measurable influx of K
+
, and the intracellular concentration of potassium was less than 29 m
m
. There was, however, considerable binding of K
+
to the “surface” of microcysts. It is postulated that the greatly reduced intracellular concentration of potassium helps to maintain the microcyst in its dormant state and protects it against enzymatic break-down.
Histidine-Mediated Control of Tryptophan Biosynthetic Enzymes in
Neurospora crassa
Authors: Carsiotis M. , Jones R. F. , Lacy Ann M. , Cleary T. J. , Fankhauser D. B.
Published: January 2020

The formation of the five tryptophan biosynthetic enzymes of
Neurospora crassa
was shown to be derepressed in histidine-starved cells. This histidine-mediated derepression was not due to a lowered intracellular concentration of tryptophan in these cells. Furthermore, histidine-mediated derepression of tryptophan enzymes was found to be coordinate and not subject to reversal by tryptophan of either exogenous or biosynthetic origin. The synthesis of tryptophan enzymes also was found to be coordinate in cells which were not histidine-starved. Although histidine is clearly involved in regulating the synthesis of tryptophan enzymes, it did not prevent either tryptophan-mediated derepression of tryptophan enzymes or indole-3-glycerol phosphate-mediated derepression of tryptophan synthetase.
Necessity of Calcium Ion for Cell Division in
Lactobacillus bifidus
Authors: Kojima Masami , Suda Shozo , Hotta Susumu , Hamada Koyata , Suganuma Atsushi
Published: January 2020

Electron microscopy revealed that reversion of the bifid form to the bacilloid form of
Lactobacillus bifidus
takes place by cross wall formation, the process requiring available calcium ions.
Purification and Properties of Colicin K
Authors: Kunugita Kiyohiko , Matsuhashi Michio
Published: January 2020

Colicin K was purified from
Escherichia coli
K-235 (Col K) as a single protein free from polysaccharide. Its molecular weight was estimated at 70,000.
Variant of Penicillinase Mediated by an R Factor in
Escherichia coli
Authors: Sawai Tetsuo , Takahashi Katsutoshi , Yamagishi Saburo , Mitsuhashi Susumu
Published: January 2020

The penicillinase from an
Escherichia coli
strain harboring an R factor R
GN823
was purified and its properties were compared with those of a known type I penicillinase mediated by R factors. The molecular weight and
S
20,w
of the enzyme were 22,600 and 2.42
S
, respectively. The isoelectric point of the enzyme was 6.9. These values are clearly different from those of type I penicillinase. The specific activity of the enzyme was 84,700 units per mg of the purified enzyme protein, which is about 20 times higher than that of the type I penicillinase. However, similarities were observed between the enzyme and the type I-penicillinase at optimal
p
H (6.5 to 7.0), optimal temperature (40 to 45C), substrate specificity, Michaelis constants for penicillins and cephaloridine, and effect of inhibitors. Furthermore, antiserum against type I penicillinase showed cross-reaction against this enzyme. The enzyme was named type Ib penicillinase, and the original type I penicillinase was renamed type Ia-penicillinase.
Conservation and Transfer of
Escherichia coli
Genetic Segments by Partial Diploid Hfr Strains of
Salmonella typhosa
Authors: Johnson E. M. , Easterling S. B. , Baron L. S.
Published: January 2020

Heterozygous, partial diploid hybrids were obtained in a
Salmonella typhosa
Hfr strain by using it as the recipient in a mating with the
Escherichia coli
Hfr donor WR2004 (O...
proA
...
leu
). Three of these
S. typhosa
Hfr hybrids were observed to mobilize and transfer the diploid
E. coli
genes, at high frequencies, to an
E. coli
recipient. The gradient of transfer frequencies of
E. coli
markers from these
S. typhosa
Hfr hybrids was similar to that observed with
E. coli
Hfr WR2004, from which they were derived. Interrupted matings with one of these
S. typhosa
Hfr hybrids, designated WR4272, showed the entry times for the
pro
A,
thr
−
leu
, and
argB E. coli
diploid markers to be identical to the times obtained for these markers with
E. coli
Hfr WR2004. Also, the pattern of unselected inheritance of the diploid
E. coli
markers of
S. typhosa
Hfr hybrid WR4272 was similar to that observed with the chromosomal markers of
E. coli
Hfr WR2004. It was concluded that
S. typhosa
Hfr hybrid WR4272 contains, in addition to its
Salmonella
genome, a physically continuous
E. coli
chromosomal segment which is genetically complete from
proA
to at least the
strA
locus. The two other
S. typhosa
Hfr hybrids, on the basis of transmission frequency gradients, appeared to contain a continuous
E. coli
diploid segment complete from
proA
through the
fuc
locus. Other classes of
S. typhosa
Hfr hybrids, derived from mating with
E. coli
Hfr WR2010 (O...
tna
...
xyl
), were also observed to transfer
E. coli
genes at high frequency.
Organization of Polyaromatic Biosynthetic Enzymes in a Variety of Photosynthetic Organisms
Authors: Berlyn Mary B. , Ahmed S. I. , Giles Norman H.
Published: January 2020

Sucrose density gradient centrifugation was used to estimate the molecular weights and determine possible physical aggregation of the enzymes catalyzing steps 2 to 6 in pre-chorismic acid polyaromatic biosynthesis in
Anabaena variabilis, Chlamydomonas reinhardi, Euglena gracilis, Nicotiana tabacum
, and
Physcomitrella patens
. In
A. variabilis
, the five enzymes are separable. Similar results were obtained for
P. patens, N. tabacum
, and
C. reinhardi
extracts, except that dehydroshikimate reductase and dehydroquinase were not separable by this method. Evidence is presented for an enzyme aggregate containing five activities, with a molecular weight of approximately 120,000 in
E. gracilis;
dissociation of this aggregate into components corresponding to molecular weight of ca. 60,000 is also observed. Preliminary evidence concerning the enzymatic composition of the 60,000-molecular-weight components is presented and discussed. Similarities between the
E. gracilis
polyaromatic aggregate and that of
Neurospora crassa
are discussed.
Interaction Between Histidyl Transfer Ribonucleic Acid and the First Enzyme for Histidine Biosynthesis of
Salmonella typhimurium
Authors: Kovach John S. , Phang James M. , Blasi Francesco , Barton Robert W. , Ballesteros-Olmo Antonio , Goldberger Robert F.
Published: January 2020

Previous studies showed that the enzyme (phosphoribosyltransferase) which catalyzes the first step of the histidine pathway in
Salmonella typhimurium
plays a role in regulation of the histidine operon. Since histidyl transfer ribonucleic acid (His-tRNA) is required for repression of the histidine operon, we considered the possibility that the role of phosphoribosyltransferase might be realized through an interaction with His-tRNA. One prediction inherent in this idea is that the enzyme should interact with His-tRNA in vitro. Evidence is presented for such an interaction. Binding of
3
H-His-tRNA to purified phosphoribosyltransferase was tested on Sephadex columns and on nitrocellulose filters. The enzyme was found to have a high affinity for tRNA. Comparing the binding of
3
H-His-tRNA with that of tRNA aminoacylated with other
3
H-amino acids disclosed that the binding of the histidyl species of tRNA is favored over that of other species and is dependent upon magnesium-ion concentration.
Isolation and Mapping of Phosphotransferase Mutants in
Escherichia coli
Authors: Epstein Wolfgang , Jewett Susan , Fox C. Fred
Published: January 2020

Mutants of
Escherichia coli
K-12 defective in enzyme I or Hpr, the two common components of the phosphoenolpyruvate-dependent phosphotransferase system, were isolated by a simple, direct method. The
ptsI
locus, the structural gene for enzyme I, and the
ptsH
locus, the site of mutations leading to loss of Hpr activity, are adjacent genes and could be part of a single operon. These two genes lie between the
purC
and
supN
markers in the order:
strA... guaB-purC-ptsI-ptsH-supN-dsdA... his
.
Ultrastructure of
Azotobacter vinelandii
Authors: Vela G. R. , Cagle G. D. , Holmgren P. R.
Published: January 2020

Vegetative cells and cysts of
Azotobacter vinelandii
12837 were prepared for electron microscopy by several methods assumed to preserve structural details destroyed by techniques previously reported in the literature. Examination of large numbers of cells and cysts by these methods revealed four structural details not reported previously: intine fibrils, intine vesicles, intine membrane, and microtubules. The intine fibrils form a network in the gel-like homogeneous matrix of the CC2 layer. Intine vesicles which seem to originate in the cell wall complex of the central body are seen in the intine and exine of cysts. Analogous structures are found on vegetative cells. The intine is divided into two chemically distinct areas by the two-layered intine membrane. Microtubules, previously reported only in vegetative cells, were found in cysts.
Gliding Motility Mutants of
Myxococcus xanthus
Authors: Burchard Robert P.
Published: January 2020

Two gliding motility mutants of
Myxococcus xanthus
are described. The semimotile mutant (SM) originated by high-frequency segregation from the motile FB
t
strain. Segregation was enhanced by acridine dye treatment. SM cells glide only when apposed to other cells in a swarm. The nonmotile strain (NM) originated by mutation from SM. NM cells neither glide individually nor cooperatively. FB
t
, SM, and NM are indistinguishable with respect to fine structure, vegetative growth rate, glycerol-induced microcyst formation, spheroplasting, bacteriophage sensitivity, and responses to light. The motility mutants are more resistant to penicillin and more sensitive to actinomycin D than is the gliding wild type. The NM mutant is also a morphogenetic mutant; it is unable to form fruiting bodies.
Regulation of Cell Division inEscherichia coli:Characterization of Temperature-Sensitive Division Mutants
Authors: Reeve John N. , Groves David J. , Clark D. Joseph
Published: January 2020

A temperature-sensitive division mutant ofEscherichia coliwas isolated by using differential filtration to select for filaments at 42 C and normal cells at 30 C. Cells shifted from 30 to 42 C stop dividing almost immediately, suggesting the temperature-sensitive element is required for cell division late in the cell cycle. Cells returned to 30 from 42 C divide abruptly, suggesting accumulation of division potential at 42 C. Inhibitors of protein, deoxyribonucleic acid, and ribonucleic acid synthesis do not block division during the recovery period at 30 C. Cycloserine does not stop cell division, vancomycin shows some effect on cell division, whereas penicillin completely stops cell division during this period. The addition of high concentrations of NaCl to filaments at 42 C results in a burst of cell division. The final cell number is equivalent to the control which is grown at 30 C if sufficient salt is added (11 g/liter, final concentration). After the original burst, cell division ceases at the nonpermissive temperature even at increased osmolality. Chloramphenicol, puromycin, vancomycin, and penicillin prevent division during the recovery in the presence of NaCl. Kinetic data indicate division potential decays to a reversible inactive intermediate which rapidly decays to an irreversible inactive form. Conversion of division potential to the inactive form is correlated with a 100- to 1,000-fold derepression of the synthesis of division potential. The mutation appears to involve a stage in cross-wall synthesis which is required during the terminal stages of division.
Characterization of Labeled Residues from 5-Diazouracil-
2
-
14
C
Incorporated into Ribonucleic Acids of Filamentous
Escherichia coli
Authors: Fister George , Previc Edward , Richardson Sheila
Published: January 2020

E. coli
B, filamented with 5-diazouracil (DZU)-
2
-
14
C
, yielded ribonucleic acid (RNA)-(DZU-
2
-
14
C
) which was converted by pancreatic ribonuclease to
14
C-mono-and oligo-nucleotides. The mixed
14
C-mononucleotides isolated by diethylaminoethyl-cellulose fractionation were identified as cytidylic, uridylic, and hydroxyuridylic acids, by using a combination of paper chromatography and treatment with alkaline phosphatase and cytidine deaminase. Rifampin blocked incorporation of DZU-
2
-
14
C
under conditions which inhibit RNA synthesis. Division inhibition by DZU-
2
-
14
C
and the incorporation into
Escherichia coli
B were retarded by uracil but not by other RNA bases. In a pyrimidine-requiring
E. coli
, DZU substituted for uracil or cytosine to an extent limited by toxic effects. Cytosine and uracil retarded these effects and retarded the incorporation of DZU-
2
-
14
C
into the pyrimidineless strain. A small proportion of DZU-
2
-
14
C
was converted by the latter strain into hydroxyuridylic acid, but the bulk of the incorporated label was in cytidylic and uridylic acid, as in the wild strain.
Small Colonies of
Clostridium sticklandii
Resulting from Nitrosoguanidine Treatment and Exhibiting Defects in Catabolic Enzymes
Authors: Schwartz Arnold C. , Stadtman Thressa C.
Published: January 2020

Several strains of
Clostridium sticklandii
, isolated from small colonies arising after treatment with 1-methyl-3-nitro-1-nitrosoguanidine, exhibited markedly depressed activities of certain catabolic enzyme systems known to provide energy to the organism in the form of adenosine triphosphate. In some of these strains the levels of glycine reductase, the ability to ferment lysine to fatty acids and ammonia, and formate-dependent 2,3-5-triphenyltetrazolium chloride reduction were only 0 to 10% of that of the wild type. Another subgroup of mutants exhibited activities of some of these enzymes from 1.3 to 3 times higher than those of the wild type. Small-colony mutants of an obligate anaerobe, like those of oxygen-utilizing organisms, can therefore be due to defects in one or more of their energy-providing systems. The merits of small-colony formation as an auxiliary marker for the isolation of catabolic mutants are discussed.
Comparison of the Envelope Protein Compositions of Several Gram-Negative Bacteria
Authors: Schnaitman Carl A.
Published: January 2020

Five gram-negative species contained one or two major protein species with electrophoretic mobilities similar to the major protein of the
Escherichia coli
cell wall.
Small Ribosomal Ribonucleic Acid Species of
Saccharomyces cerevisiae
Authors: Udem Stephen A. , Kaufman Karen , Warner Jonathan R.
Published: January 2020

Yeast ribosomes contain two small molecular-weight species of ribonucleic acid (RNA), in addition to transiently associated transfer RNA. The 5
S
RNA species is part of the large ribosomal subunit and appears to be exactly the same size as 5
S
RNA from other organisms. There is another RNA molecule, approximately 5.8
S
or 150 nucleotides in size, which is noncovalently attached to the 25
S
ribosomal RNA and can be freed by gentle heating or urea treatment. Neither 5 nor 5.8
S
RNA are methylated. The 5.8
S
RNA is probably derived from a part of the 35
S
precursor RNA, whereas the 5
S
RNA is made de novo. These results substantiate the notion that ribosome biosynthesis in yeast is analogous to that of the higher eukaryotes.
Rate of Ribosome Production in
Bacillus licheniformis
Authors: Van Dijk-Salkinoja M. S. , Planta R. J.
Published: January 2020

The ribosome content of exponential-phase cells of
Bacillus licheniformis
was measured at three different growth rates. The average number of ribosomes per cell was about 92,000, 34,400, or 12,500 70
S
equivalents in balanced cultures growing at 37 C with generation times of 35, 60, and 120 min, respectively. Since the ribosomal particles were shown to be metabolically stable in exponentially growing cells, these figures implicate large differences in the quantity of ribosomes synthesized per unit of time in an individual cell grown under the various conditions. Nevertheless, the time required for the biosynthesis of a single 50
S
subunit was constant (about 10 min) and independent of the specific growth rate of the cell (within the limits studied). These results show that ribosome production is not regulated by control of the rate of assemblage of individual ribosomes, but rather by control of the
number
of the ribosomes in manufacture at a time.
Purification and Properties of a Hydrogenase from
Desulfovibrio vulgaris
Authors: Haschke Richard H. , Campbell L. Leon
Published: January 2020

The soluble hydrogenase of
Desulfovibrio vulgaris
was purified and some of its properties are described. The molecular weight was determined for the enzyme by sedimentation equilibrium (45,400) and amino acid analysis (44,800). The hydrogenase appears to be a loosely coiled molecule or to have a high axial ratio, which is reflected in an unusually low sedimentation coefficient (2.58
S
) and a low diffusion coefficient (D 5.85). The molecular weight of the hydrogenase (41,000), as calculated by the Svedberg equation, was in general agreement with the sedimentation equilibrium molecular weight. Amino acid analysis revealed the presence of six halfcystine residues per mole of enzyme and a total of 417 amino acid residues. The specificity of the hydrogenase and its capacity to reduce certain low potential dyes and cytochrome
c
3
was studied. Metal analysis of the hydrogenase indicated the presence of 1 mole of ferrous iron per mole of enzyme.
Catabolite Repression of Tryptophanase in
Escherichia coli
Authors: Botsford James L. , DeMoss R. D.
Published: January 2020

Catabolite repression of tryptophanase was studied in detail under various conditions in several strains of
Escherichia coli
and was compared with catabolite repression of β-glactosidase. Induction of tryptophanase and β-galactosidase in cultures grown with various carbon sources including succinate, glycerol, pyruvate, glucose, gluconate, and arabinose is affected differently by the various carbon sources. The extent of induction does not seem to be related to the growth rate of the culture permitted by the carbon source during the course of the experiment. In cultures grown with glycerol as carbon source, preinduced for β-galactosidase or tryptophanase and made permeable by ethylenediaminetetraacetic acid (EDTA) treatment, catabolite repression of tryptophanase was not affected markedly by the addition of cAMP (3′,5′-cyclic adenosine monophosphate). Catabolite repression by glucose was only partially relieved by the addition of cAMP. In contrast, under the same conditions, cAMP completely relieved catabolite repression of β-galactosidase by either pyruvate or glucose. Under conditions of limited oxygen, induction of tryptophanase is sensitive to catabolite repression; under the same conditions, β-galactosidase induction is not sensitive to catabolite repression. Induction of tryptophanase in cells grown with succinate as carbon source is sensitive to catabolite repression by glycerol and pyruvate as well as by glucose. Studies with a glycerol kinaseless mutant indicate that glycerol must be metabolized before it can cause catabolite repression. The EDTA treatment used to make the cells permeable to cAMP was found to affect subsequent growth and induction of either β-galactosidase or tryptophanase much more adversely in
E. coli
strain BB than in
E. coli
strain K-12. Inducation of tryptophanase was reduced by the EDTA treatment significantly more than induction of β-galactosidase in both strains. Addition of 2.5 × 10
−3
m
cAMP appeared partially to reverse the inhibitory effect of the EDTA treatment on enzyme induction but did not restore normal growth.
Purification and Thermal Stability of Intact
Bacillus subtilis
Flagella
Authors: Dimmitt K. , Simon M.
Published: January 2020

Flagella were prepared and purified in a relatively intact form from bacterial lysates. Immunochemical tests showed that over 95% of the protein in the final preparation consisted of flagellar antigen. These flagella are more stable to thermal denaturation than flagella filaments obtained by shearing. Their thermal properties more closely resemble those of flagella in the native state on bacteria. The presence of the hook structure is responsible for this extra stability.
Cellular Morphology of Newly Isolated
Mycoplasma hominis
Strains
Authors: Bredt W.
Published: January 2020

Cells of
Mycoplasma hominis
growing in laboratory media for the first time were observed by phase contrast and identified by their reaction to homologous antiserum.
Bacteriophage Attachment Sites, Serological Specificity, and Chemical Composition of the Lipopolysaccharides of Semirough and Rough Mutants of
Salmonella typhimurium
Authors: Lindberg A. A. , Hellerqvist C. G.
Published: January 2020

Extracted lipopolysaccharides (LPS) from one smooth, one semirough, and five rough mutants of
Salmonella typhimurium
LT2 or LT7, for which the chemical structure of the polysaccharide chain had been elucidated by using methylation analysis, were characterized with passive hemagglutination inhibition and phage inactivation experiments. Each addition of a sugar residue to a LPS from chemotype Rc was reflected in changed serological reactivity and phage-inhibiting activity of a collection of bacteriophages of the isolated LPS. Thus, certain criteria can be established for a classification of rough mutants of
S. typhimurium
. The observation that the serological RII specificity corresponds to a completed common core polysaccharide was verified. The serological RI specificity was found in LPS with terminal
d
-galactose I residues. One of the mutants, SL733, yielded a LPS which cross-reacted with anti-O5 factor serum although the polysaccharide was virtually free from contaminating O-specific material. The O5 reactivity was destroyed by alkaline treatment of SL733 LPS. The smooth- and rough-specific Felix O-l (FO) and the rough-specific 6SR and Br2 phages were shown to have their receptors in the LPS. There was a good correlation between the adsorption rate constant to whole cells and the phage inhibiting activity of isolated LPS suggesting that the LPS exert the major influence on the attachment of these phages to the bacteria. The polysaccharide structures in the LPS necessary for attachment of the 6SR and Br2 phages were defined. It was found that measuring the phage-inhibiting properties of isolated LPS as PhI
50
(LPS concentration required to inactivate 50% of the phages under defined conditions) was a more sensitive method for a characterization of the LPS than the serological and chemical assays used.
Mutation Affecting Activity of Several Distinct Amino Acid Transport Systems in
Saccharomyces cerevisiae
Authors: Grenson M. , Hennaut C.
Published: January 2020

Mutations at the
apf
locus selectively depress the activity of a number of distinct amino acid permeases in
Saccharomyces cerevisiae
. The activity of the general amino acid permease and specific amino acid permeases is decreased, but the uptake of pyrimidines and adenine is unaffected. Mutations at the
apf
locus are allelic to the
aap
mutation isolated by Surdin et al. Amino acid uptake is normal in a heterozygous diploid (
apf
/+) and in a tetraploid strain with only one functional allele at the
apf
locus.
Paracoccidioides brasiliensis
: Conversion of Yeastlike Forms into Mycelia in Submerged Culture
Authors: Martínez J. R. Ramírez
Published: January 2020

Details of the sequential morphological changes occurring during yeastlike to mycelial-form conversion of the dimorphic pathogen
Paracoccidioides brasiliensis
are described and illustrated by photomicrographs. Conversion of yeastlike to hyphal morphology was initiated by changing the temperature of incubation from 37 to 23 C. Production by the parent yeastlike cells of elongated buds developing into hyphae started to be conspicuous after 24 hr of incubation at 23 C. After 120 hr of incubation, growth was almost exclusively filamentous. Direct transformation of parent yeastlike cells into hyphae was not observed. Dry weight increased continuously during the conversion process in spite of the gradual disappearance of the parent yeastlike cells. Concurrent studies showed that changes in ribonucleic acid and deoxyribonucleic acid content per unit dry weight are about the same whether the yeastlike cells are undergoing conversion at 23 C or growing normally at 37 C, and that deoxyribonucleic acid synthesis is apparently required for bud formation in both cases.
Regulation of Chromosome Replication in
Bacillus subtilis
: Effects of Amino Acid Starvation in Strain W23
Authors: Copeland Jamec C.
Published: January 2020

Amino acid starvation allows limited synthesis of deoxyribonucleic acid (DNA) in
Bacillus subtilis
strain W23. DNA synthesis increased by about 30% after leucine starvation and by about 60% after histidine starvation. Genetic analysis on the DNA synthesized after amino acid starvation showed that all genetic markers examined have replicated, regardless of which amino acid was starved for. Initially, all markers replicated equally, but upon further replication, the
thr cysB
and the
argA
to
lys
regions replicated ahead of their neighboring, proximal regions. This could indicate that preferred stopping sites exist in these regions or additional sites from which replication can originate reside there. The results suggest that chromosome replication continues from those sites where it had stopped during amino acid starvation.
R Factor Deoxyribonucleic Acid in Chromosomeless Progeny of
Escherichia coli
Authors: Inselburg Joseph
Published: January 2020

The deoxyribonucleic acid (DNA) of resistance (R) factor 222 carried by
Escherichia coli
strain P678-54 was found in the normally chromosomeless progeny (minicells) of that strain. The entry of the R222 DNA into minicells appears to be via segregation at the time of their formation from normal cells. The R222 DNA can replicate in minicells although the extent of its replication appears to be limited. An analysis of the R222 DNA structure indicates that it exists in minicells as double-stranded linear, open circular, and twisted circular monomers (molecular weight, about 6.2 × 10
7
daltons). The monomers visualized by electron microscopy are 31.0 ± 0.5 μm in length. An examination of the effect of acridine orange on the replication of R222 and colicin E1 DNA indicates the dye intereferes with plasmid DNA replication.
Mutant of
Bacillus subtilis
Demonstrating the Requirement of Lysis for Growth
Authors: Fan David P. , Beckman Mary M.
Published: January 2020

A temperature-sensitive mutant of
Bacillus subtilis
which has impaired ability to autolyze was isolated. The growth rate of mutant cells at high temperature can be increased by the addition of egg-white lysozyme or a
B. subtilis
autolysin. Experiments with this mutant show that lysis is essential for cell growth.
Structure of the
Chromatium
Sulfur Particle and Its Protein Membrane
Authors: Nicolson Garth L. , Schmidt Gregory L.
Published: January 2020

Sulfur particles extracted from
Chromatium vinosum
strain D were found to be bounded by a unique proteinaceous membrane. Ultrastructural examination of the membrane in Epon sections and bovine serum albumin sections and examination of negatively stained, sulfur-free membrane ghosts revealed a monomolecular sheet composed of 2.5-nm globular components. The internal sulfur was found to bind large amounts of a variety of negative stains and to form myelin-like structures upon rupture of the surrounding membrane.
Disruption of Yeast Membranes by Methylphenidate
Authors: Spoerl Edward
Published: January 2020

Methylphenidate blocked sorbose uptake and loss by yeast spheroplasts and, at higher concentrations (30 m
m
), disrupted the spheroplasts. At still higher concentrations (70 m
m
), methylphenidate also ruptured the membranes of whole yeast cells; sorbose and materials absorbing at 280 nm were lost from the cells, and methylene blue stained them. Intracellular structures were extensively affected, as shown by electron micrographs, and were more sensitive to disruption by methylphenidate than the external membrane.
N
-ethylmaleimide and Ca
2+
enhanced the rupture of external membranes by methylphenidate.
Uranyl Nitrate Inhibition of Transport Systems in
Saccharomyces cerevisiae
Authors: Maxwell W. A. , Metzler R. , Spoerl Edward
Published: January 2020

Uranyl nitrate inhibited the transport of several amino acids, a vitamin, and a disaccharide into yeast.
Genetic Analysis of Pleiotropic Negative Sporulation Mutants in
Bacillus subtilis
Authors: Hoch James A.
Published: January 2020

Genetic studies were undertaken on 14 pleiotropic negative sporulation mutants. These mutants (
spoA
) which are blocked early in the sporulation process were found to map near the terminus of the
Bacillus subtilis
chromosome in a region enriched in genes involved in spore formation. Two- and three-factor crosses by transduction and transformation led to the conclusion that the pleiotropic
spoA
mutations formed a linked cluster. The genetic distance across the cluster calculated from transformation data was compatible with the mutant sites defining a single gene. Suppressor studies revealed that either a nonsense or missense mutation in the
spoA
locus generated a pleiotropic negative phenotype. It was concluded that the locus codes for a protein, and the absence of this protein is responsible for the pleiotropic phenotype.
Aurintricarboxylic Acid, a Preferential Inhibitor of Initiation of Protein Synthesis
Authors: Siegelman Frederic , Apirion David
Published: January 2020

The effect of aurintricarboxylic acid (ATA) was tested on various aspects of protein synthesis directed by the natural messenger ribonucleic acid (RNA) isolated from R17 RNA bacteriophage. The effects of various levels of ATA (up to 1,000 μ
m
) were tested on overall protein synthesis as well as on binding of messenger RNA and fmet-transfer RNA to ribosomes and on the addition of the 50
S
ribosome to the 30
S
ribosome initiation complex. All of the reactions tested could be inhibited by ATA, and none of the tested steps was found to be uniquely sensitive to it. However, the total initiation steps were more sensitive to this chemical than the elongation steps; thus, under appropriate conditions this chemical can preferentially inhibit initiation while elongation of the polypeptide chain is not appreciably affected.
Colicin Tolerance Induced by Ampicillin or Mutation to Ampicillin Resistance in a Strain ofEscherichia coliK-12
Authors: Burman Lars G. , Nordström Kurt
Published: January 2020

A mutant (G11el) ofEscherichia coliselected as being resistant to ampicillin and showing signs of an envelope defect was also found to be tolerant to colicins E2 and E3. The colicin tolerance of G11el could be partially repressed by Mg2+ions. Transition from tolerance to sensitivity and vice versa by shifting the concentration of Mg2+in the growth medium required several generations. This indicated that synthesis of new envelope material was needed for transition. Previous physiological results have indicated a change in the envelope lipopolysaccharide (LPS) of G11el. However, chemical analyses revealed no differences in carbohydrate composition between LPS from G11el and its parent strain G11al. Genetic experiments showed that the mutation in G11el is located at about 20 min on theE. coliK-12 chromosome. The mutation was dominant over wild type in partial diploids with the mutation located on the episome. Because colicin tolerance was the most striking phenotypic effect as a result of mutation in the actual locus, this gene will be namedtolDuntil the exact gene product is known. Spheroplasts formed from G11al and G11el by ethylenediaminetetraacetate-lysozyme treatment did not adsorb colicin E2; however, penicillin spheroplasts of G11al and G11el were tolerant to colicin E2. Thus, colicin tolerance can be induced biochemically. It is suggested that colicin tolerance often is a secondary consequence of a change in the cell envelope.
Mutants of
Staphylococcus aureus
with Increased Sensitivity to Ultraviolet Radiation
Authors: Goering R. V. , Pattee P. A.
Published: January 2020

Nitrosoguanidine (NG) mutagenesis of
Staphylococcus aureus
resulted in the isolation of eight mutants exhibiting 3 to 28 times greater sensitivity to ultraviolet (UV) radiation. These mutants were further characterized by their ability to repair UV-irradiated bacteriophage, to act as recipients in the transduction of antibiotic resistance, and their sensitivity to NG. Based on the available data, six of these mutants are reduced in their ability to perform host-cell reactivation. One of the remaining two mutants may be deficient in post-replication repair.
Mechanism of Inactivation of Transforming Deoxyribonucleic Acid by X Rays
Authors: Randolph M. L. , Setlow Jane K.
Published: January 2020

Transforming deoxyribonucleic acid (DNA) from
Haemophilus influenzae
was exposed to X rays either in phosphate buffer or in 10% yeast extract. Relations between determinations of biological inactivation, DNA uptake by competent
H. influenzae
, integration of DNA into the competent cell genome, and induced single-and double-strand breaks indicate that transforming DNA is inactivated by the direct and the indirect effect of X radiation primarily because integration of DNA is prevented as a result of the production of double-strand breaks.
Regulation at the Phosphoenolpyruvate Branchpoint in
Azotobacter vinelandii
: Phosphoenolpyruvate Carboxylase
Authors: Liao Cheng-Liang , Atkinson Daniel E.
Published: January 2020

Phosphoenolpyruvate carboxylase (EC 4.1.1.31) from
Azotobacter vinelandii
, like the corresponding enzyme from other organisms, is activated by acetyl coenzyme A and inhibited by
l
-aspartate. Both modifiers affect primarily the affinity of the enzyme for phosphoenolpyruvate. This is the first enzyme with a strictly anaplerotic (intermediate-replacing) function to be tested for response to the adenylate energy charge; it is entirely insensitive to variation in charge. The results suggest that carboxylation of phosphoenolpyruvate in this organism is controlled by negative feedback from aspartate and by the stimulatory effect of acetyl coenzyme A. The adenylate energy charge may be expected to affect the rate of this reaction indirectly through its effects on the concentrations of acetyl coenzyme A and
l
-aspartate.
Cell Wall Polysaccharide Biosynthesis by Membrane Fragments from
Streptococcus pyogenes
and Stabilized L-Form
Authors: Cohen Murray , Panos Charles
Published: January 2020

The formation and composition of a cell wall rhamnose-containing polysaccharide by membrane fragments from
Streptococcus pyogenes
and its stabilized L-form were compared. Also, the effect of prior treatment on the ability of coccal whole-cell and membrane fragments to incorporate radioactivity from thymidine diphosphate-
14
C-rhamnose, and the results of subsequent attempts to remove labeled polysaccharide from such membranes are given. L-form membrane fragments were capable of only 10% uptake of
14
C-rhamnose from this nucleotide as compared with streptococcal membranes. However, once bound, both membrane fragments polymerized rhamnose to the same extent. These findings tend to negate the almost complete lack of polymeric rhamnose within the intact L-form as being due to the absence of membrane enzymes necessary for the transfer of rhamnose from a suitable precursor to membrane acceptor sites or enzymes responsible for rhamnose polymerization. Degradation of labeled rhamnose polysaccharide after isolation from coccal membranes by mild acid hydrolysis showed muramic acid and glucosamine to be attached. This same polysaccharide from L-form membrane fragments was devoid of amino sugars. These data suggest the possible involvement of amino sugars in the attachment of cell wall polymeric rhamnose to the streptococcal cytoplasmic membrane. The absence of attached amino sugars to rhamnose polysaccharide from L-form membrane fragments is discussed in terms of this organism's continued inability for new cell wall formation. The isolation, from streptococcal membrane fragments, of a polysaccharide containing rhamnose and amino sugars common to at least two different streptococcal cell wall-type polymers was demonstrated.
Separate Nitrite, Nitric Oxide, and Nitrous Oxide Reducing Fractions from
Pseudomonas perfectomarinus
Authors: Payne W. J. , Riley P. S. , Cox C. D.
Published: January 2020

Pseudomonas perfectomarinus
was found to grow anaerobically at the expense of nitrate, nitrite, or nitrous oxide but not chlorate or nitric oxide. In several repetitive experiments, anaerobic incubation in culture media containing nitrate revealed that an average of 82% of the cells in aerobically grown populations were converted to the capacity for respiration of nitrate. Although they did not form colonies under these conditions, the bacteria synthesized the denitrifying enzymes within 3 hr in the absence of oxygen or another acceptable inorganic oxidant. This was demonstrated by the ability, after anaerobic incubation, of cells and of extracts to reduce nitrite, nitric oxide, and nitrous oxide to nitrogen. From crude extracts of cells grown on nitrate, nitrite, or nitrous oxide, separate complex fractions were obtained that utilized reduced nicotinamide adenine dinucleotide as the source of electrons for the reduction of (i) nitrite to nitric oxide, (ii) nitric oxide to nitrous oxide, and (iii) nitrous oxide to nitrogen. Gas chromatographic analyses revealed that each of these fractions reduced only one of the nitrogenous oxides.
Kinetic Characteristics of the Two Glucose Transport Systems in
Neurospora crassa
Authors: Schneider R. P. , Wiley W. R.
Published: January 2020

Glucose is transported across the cell membrane of
Neurospora crassa
by two physiologically and kinetically distinct transport systems. System II is repressed by growth of the cells in 0.1
m
glucose. System I is synthesized constitutively. The apparent
K
m
for glucose uptake by system I and system II are 25 and 0.04 m
m
, respectively. Both uptake systems are temperature dependent, and are inhibited by NaN
3
and 2,4-dinitrophenol. Glucose uptake by system II was not inhibited by fructose, galactose, or lactose. However, glucose was shown to be a noncompetitive inhibitor of fructose and galactose uptake. The transport rate of [
14
C]3-0-methyl-
d
-glucose (3-0-MG) was higher in cells preloaded with unlabeled 3-0-MG than in control cells. The rate of entry of labeled 3-0-MG was only slightly inhibited by the presence of NaN
3
in the medium. Further, NaN
3
caused a rapid efflux of accumulated [
14
C]3-0-MG. These data imply that the energetic step in the transport process prevents efflux.
Pleiotropic Effect of the
recA
Gene of
Escherichia coli:
Uncoupling of Cell Division from Deoxyribonucleic Acid Replication
Authors: Inouye Masayori
Published: January 2020

A defective
recA
gene, which is involved in recombination, is shown in this article to permit limited cell division, when deoxyribonucleic acid (DNA) synthesis is blocked. Thymidine starvation or nalidixic acid blocked DNA synthesis, and stopped cell division of a
rec
+
thy
−
strain of
Escherichia coli
. However, with the same treatments, a
recA
thy
−
strain could continue to divide for at least 5 hr, and cell numbers increased 2.5- to 4-fold. After several hours of thymidine starvation, the culture contained very long cells (snakes) and small (normal-sized) cells. The short cells contained very little, if any, DNA. Cells of all ages divided in the absence of thymidine. Specific differences in membrane proteins were observed between thymidine-starved
rec
+
and
recA
cells, as expected from previous experiments in which these proteins were associated with cell division and DNA synthesis. It is proposed that septum formation is controlled negatively by the
recA
+
gene.
Purification and Properties of α-Ketoglutarate Reductase from
Micrococcus aerogenes
Authors: Lerud R. F. , Whiteley H. R.
Published: January 2020

Micrococcus aerogenes
grown in media containing glutamate has high levels of glutamate dehydrogenase and α-ketoglutarate reductase. The latter enzyme catalyzes the reversible reduction of α-ketoglutarate to α-hydroxyglutarate in the presence of reduced nicotinamide adenine dinucleotide (NADH). The enzyme has a high specificity for both substrates in either direction and displays Michaelis-Menten kinetics at moderate substrate concentrations.
K
m
values of 0.12 to 0.17 m
m
α-ketoglutarate and 0.3 m
m
NADH for the forward reaction were calculated from data obtained at low substrate concentrations. At high concentrations, this reaction was inhibited by both substrates. The reverse reaction, which proceeded at 0.1 to 0.2 times the rate of the forward reactions, was inhibited by one of the products, α-ketoglutarate.
K
m
values for the substrates of this reaction were 10 m
m
for α-hydroxyglutarate and 1 m
m
for nicotinamide adenine dinucleotide. α-Ketoglutarate reductase has a molecular weight of 7.5 × 10
4
to 8.2 × 10
4
and is composed of identical polypeptide chains with a molecular weight of 3.6 × 10
4
to 3.8 × 10
4
.
Morphogenetic Aspects of Murein Structure and Biosynthesis
Authors: Schwarz Uli , Leutgeb Werner
Published: January 2020

The shape of
Escherichia coli
is fixed by the form of the sacculus. This sacculus is a macromolecule made up from the polymer murein. In an investigation of the possible factors determining the shape of the sacculus, we attempted to resolve between two fundamental alternatives. (i) Is the shape of the sacculus automatically fixed by its chemical composition? or (ii) does a special morphogenetic system exist which determines the shape of the sacculus? An analysis of sacculi from cells grown in poor and rich media and harvested at different stages of growth was made. Significant variations in the composition of murein were found, whereas the general shape of the cells remained unchanged. This finding stands opposed to the assumption of a strict correlation between chemistry and shape of the sacculus. The second alternative was investigated by attempting to change artificially the shape of the sacculus by modifying the form of the hypothetical morphogenetic system. Rod-shaped cells were converted into spherical spheroplasts which were subsequently allowed to reform a new spherical sacculus. In chemical composition this spherical sacculus was found to be indistinguishable from the rod-shaped sacculus. This finding is taken as evidence for the existence of a distinct morphogenetic apparatus in the cell wall whose form is reflected by the shape of the sacculus.
Variations in the Localization of Acetyl-Coenzyme A Synthetase in Aerobic Yeast Cells
Authors: Klein Harold P. , Jahnke Linda
Published: January 2020

In cells of
Saccharomyces cerevisiae
growing aerobically for 24 hr, acetyl-coenzyme A synthetase [acetate: CoA ligase (AMP), EC 6.2.1.1] was localized principally in the microsomal fraction. On density gradients, the enzyme in such cells behaved as a low-density particle, readily separable from the soluble proteins. After 48 hr of incubation, the cells showed a bimodal distribution of enzyme, with most of the activity now sedimenting with the mitochondrial fraction and only a smaller amount with the microsomal fraction. By using density gradients, two forms of synthetase were obtained from these cells: one band denser and the other band less dense than the intact mitochondria. In all preparations containing synthetase activity, appreciable levels of phospholipids were also detected.
Quantitative Aspects of Deoxyribonucleic Acid Renaturation: Base Composition, State of Chromosome Replication, and Polynucleotide Homologies
Authors: Seidler Ramon J. , Mandel M.
Published: January 2020

The base composition of a deoxyribonucleic acid (DNA) sample affects its intrinsic rate of renaturation. In agreement with the information of Wetmur and Davidson, it was established that high guanosine plus cytosine (GC) DNA renatures faster than expected from analytical measurement of its molecular weight. A calculated correction factor of 1.8% of the observed C
0
t
.5
is required for every mole per cent GC difference from 51% GC. The correction factor is now established in the range of 32 to 65% GC. Renaturation of DNA mixtures prepared from pairs of organisms has been studied. When no similarity existed between the two organisms, the observed C
0
t
.5
of the mixture was the sum of the independently determined C
0
t
.5
values. Lack of additivity was correlated with similarities in polynucleotide sequence of the reassociating DNA molecules. A quantitative relationship was formulated to relate C
0
t
.5
values of renatured DNA mixtures to per cent binding (“homology”). Finally, it was demonstrated that DNA prepared from log-phase cells renatures faster than stationary-phase DNA and also departs from theoretical second-order kinetics.
Membrane Association of Conjugally Transferred Deoxyribonucleic Acid in
Escherichia coli
Minicells
Authors: Shull Fred W. , Fralick Joe A. , Stratton Lewis P. , Fisher William D.
Published: January 2020

The conjugally acquired deoxyribonucleic acid (DNA) of small, anucleate cells (“minicells”) of a mutant strain of
Escherichia coli
K-12 was found to be predominantly associated with the bacterial membrane. Evidence from X-irradiation studies in vivo shows that there is no decrease in DNA-membrane association under conditions which reduce the DNA to one-sixth its original size and suggests the possibility of multiple DNA-membrane association sites. Preliminary enzymatic studies indicate the involvement of protein, DNA, and lipids in the membrane association of the DNA.