bluuebunny/crossref_metadata_2025 huggingface dataset:
Conjugal Transfer of Plasmid-Borne Multiple Antibiotic Resistance in
Streptococcus faecalis
var.
zymogenes
Authors: Jacob Alan E. , Hobbs Susan J.
Published: January 2020

A strain of
Streptococcus faecalis
var.
zymogenes
, designated JH1, had high-level resistance to the antibiotics streptomycin, kanamycin, neomycin, erythromycin, and tetracycline. These resistances were lost en bloc from approximately 0.1% of cells grown in nutrient broth at 45 C. The frequency of resistance loss was not increased by growth in the presence of the “curing” agents acriflavine or acridine orange, but after prolonged storage in nutrient agar 17% of cells became antibiotic sensitive. Covalently closed circular deoxyribonucleic acid (DNA) molecules were isolated from the parental strain and from antibiotic-sensitive segregants by using cesium chloride-ethidium bromide gradients. DNA molecular species were identified by using neutral sucrose gradients. Strain JH1 contained two covalently closed circular DNA species of molecular weights 50 × 10
6
and 38 × 10
6
. An antibiotic-sensitive segregant, strain JH1-9, had lost the larger molecular species. A second sensitive segregant, strain JH1-5, had also lost the larger molecular species but a new molecular species of approximate molecular weight 6 × 10
6
was present. The antibiotic resistances that were curable from the parental strain were transferred to antibiotic-sensitive strains of
S. faecalis
and to strain JH1-9, during mixed incubation in nutrient broth at 37 C. Data to be described are interpreted to suggest that the transfer is by a conjugal mechanism. Analysis of the plasmid species in recipient clones showed that all had received the plasmid of molecular weight 50 × 10
6
. Strain JH1-5 was not a good recipient. Analysis of one successful recipient clone of JH1-5 revealed that it had gained the 50 × 10
6
molecular weight plasmid but lost the 6 × 10
6
molecular weight species. These data are interpreted to mean that the multiple antibiotic resistance is borne by a transferable plasmid of 50 × 10
6
molecular weight, and that in clone JH1-5 this plasmid suffered a large deletion leaving only a 6 × 10
6
remnant which was incompatible with the complete replicon.
Structural Interactions Between Amino Acid Residues at Positions 22 and 211 in the Tryptophan Synthetase Alpha Chain of
Escherichia coli
Authors: Murgola E. J. , Yanofsky C.
Published: January 2020

Construction and characterization of double mutants altered in the structural gene of the tryptophan synthetase alpha chain of
Escherichia coli
revealed interactions between amino acid residues at positions 22 and 211. These interactions are specific for the particular amino acid residue at position 211. The results indicate also that amino acid residues which appear to be functionally near-equivalent in one configuration may strongly influence the activity of a protein with a subsequent change at another site. Seven independent suppressors of
trpA218
(Leu22-Ser211) were isolated. Their properties suggest that all seven may suppress the codon (AGU/C) for Ser211. Six of the seven are co-transducible with
glyV
, the structural gene for the GGU/C-specific tRNA
Gly
.
Precursor of 5
S
Ribosomal Ribonucleic Acid in the Blue-Green Alga
Anacystis nidulans
Authors: Dobson Phyllis R. , Doolittle W. Ford , Sogin Mitchell L.
Published: January 2020

The maturation of 5
S
ribosomal ribonucleic acid (rRNA) in the obligately photoautotrophic unicellular blue-green alga
Anacystis nidulans
has been studied by using polyacrylamide gel electrophoresis and T1 ribonuclease oligonucleotide analysis.
A. nidulans
mature 5
S
rRNA (m5) is of approximately the same molecular weight as the 5
S
rRNA of
Escherichia coli
, and is derived by cleavage of a precursor (p5) containing a few (three to six) additional nucleotides. Some of these additional nucleotides occur at the 5′ end of the precursor molecule; others may occur at the 3′ end. Kinetic experiments indicate that precursors of mature 5
S
rRNA larger than p5 either do not exist or are very transient in
A. nidulans
. These results are discussed in relation to those obtained with other prokaryotes.
Gross Map Distances and Hfr Transfer Times in
Escherichia coli
K-12
Authors: Broda Paul , Collins J. F.
Published: January 2020

Hfr strains B4 and B8 transfer the
Escherichia coli
chromosome in opposite directions, each transferring
lac
+
as the last known marker. They were mated in concurrent crosses with the
proA leu metE lys trp purE lac
strain χ462. Analysis of the time of entry values for these markers showed that Hfr strain B8 transfers the whole chromosome more rapidly than does Hfr strain B4. In both crosses, the rate of transfer observed decelerates. If deceleration occurs as a function of the amount of chromosome transferred, the data are consistent with the markers examined being very accurately placed on the Taylor-Trotter map of the
E. coli
K-12 genome.
Mutants of
Escherichia coli
Defective in Membrane Phospholipid Synthesis: Macromolecular Synthesis in an sn-Glycerol 3-Phosphate Acyltransferase

K
m

Mutant
Authors: Bell Robert M.
Published: January 2020

sn-Glycerol 3-phosphate (G3P) auxotrophs of
Escherichia coli
have been selected from a strain which cannot aerobically catabolize G3P. The auxotrophy resulted from loss of the biosynthetic G3P dehydrogenase (EC 1.1.1.8) or from a defective membranous G3P acyltransferase. The apparent

K
m

of the acyltransferase for G3P was 11- to 14-fold higher (from about 90 μm to 1,000 to 1,250 μm) in membrane preparations from the mutants than those of the parent. All extracts prepared from revertants of the G3P dehydrogenase mutants showed G3P dehydrogenase activity, but most contained less than 10% of the wild-type level. Membrane preparations from revertants of the acyltransferase mutants had apparent

K
m

's for G3P similar to that of the parent. Strains have been derived in which the G3P requirement can be satisfied with glycerol in the presence of glucose, presumably because the glycerol kinase was desensitized to inhibition by fructose 1,6-diphosphate. Investigations on the growth and macromolecular synthesis in a G3P acyltransferase

K
m

mutant revealed that upon glycerol deprivation, net phospholipid synthesis stopped immediately; growth continued for about one doubling; net ribonucleic acid (RNA), deoxyribonucleic acid (DNA), and protein nearly doubled paralleling the growth curve; the rate of phospholipid synthesis assessed by labeling cells with
32
P-phosphate,
14
C-acetate, or
3
H-serine was reduced greater than 90%; the rates of RNA and DNA synthesis increased as the cells grew and then decreased as the cells stopped growing; the rate of protein synthesis showed no increase and declined more slowly than the rates of RNA and DNA synthesis when the cells stopped growing. The cells retained and gained in the capacity to synthesize phospholipids upon glycerol deprivation. These data indicate that net phospholipid synthesis is not required for continued macromolecular synthesis for about one doubling, and that the rates of these processes are not coupled during this time period.
Lactic Acid Translocation: Terminal Step in Glycolysis by
Streptococcus faecalis
Authors: Harold Franklin M. , Levin Eugene
Published: January 2020

Streptococcus faecalis
obtains metabolic energy chiefly from the conversion of glucose to lactic acid; the present experiments deal with the mechanism of lactic acid translocation across the cytoplasmic membrane. Efflux of [
14
C]lactate from preloaded cells was accelerated by raising the external pH, and also by the ionophores nigericin and valinomycin. These results suggest that lactate leaves the cell by an electroneutral process, presumably as lactic acid. Further evidence was obtained by studying the entry of [
14
C]lactate into nonmetabolizing cells. It appears that the membrane is essentially impermeable to the lactate anion, but allows passage of lactic acid. The most persuasive evidence is that, upon establishment of a pH gradient such that the cytoplasm was alkaline,
l
-[
14
C]lactate accumulated in the cells against the concentration gradient. Accumulation was transient, and dissipated in parallel with the collapse of the pH gradient. The concentration gradient attained at the peak was a function of the pH difference. Ionophores which are known to collapse a pH gradient, such as nigericin and valinomycin, abolished accumulation of
l
-lactate. We infer that lactic acid translocation, whether into the cells or outward, is an electroneutral process and for that reason the distribution of lactic acid across the membrane is a function of the pH of cytoplasm and medium. The specificity of translocation and its kinetic parameters suggest that it is mediated by a carrier of low specificity.
Fatty Acid Degradation in
Escherichia coli
: Requirement of Cyclic Adenosine Monophosphate and Cyclic Adenosine Monophosphate Receptor Protein for Enzyme Synthesis
Authors: Pauli Georg , Ehring Ruth , Overath Peter
Published: January 2020

The strong repression of inducible synthesis of the enzymes of fatty acid degradation by glucose can be partially relieved by the addition of cyclic adenosine 3′,5′ monophosphate (cyclic AMP) to the growth medium. This reversal of the glucose effect by cyclic AMP is
not
observed in a mutant (K29) that is unable to grow on fatty acids as sole carbon source and that was found to synthesize low levels of several enzymes specified by the
fad
regulon. In a revertant selected for the ability to grow on oleate these effects are concomitantly relieved. By both genetic (co-transduction of the mutation with the
strA
locus) and biochemical experiments (an extract of the mutant strain does not show the cyclic AMP-dependent stimulation of the deoxyribonucleic acid-directed in vitro synthesis of the enzymes of the
gal
operon), it is demonstrated that the mutant lacks functional cyclic AMP receptor protein (CR protein). It is concluded that, like many other inducible enzyme systems, expression of the enzymes of the
fad
system requires cyclic AMP and the CR protein.
Cell Wall Turnover at the Hemispherical Caps of
Bacillus subtilis
Authors: Fan David P. , Beckman Bruce E. , Beckman Mary M.
Published: January 2020

Cell walls made by
Bacillus subtilis
bacteria grown in D
2
O medium have buoyant densities in CsCl which are different from walls made by cells grown in H
2
O medium. Cell wall turnover was studied by measuring the change in wall buoyant density after a
B. subtilis
culture was shifted from growth in D
2
O medium to aeration in H
2
O medium. Walls from the hemispherical caps were isolated after preferential digestion of wall from the cylindrical regions using the
B. subtilis
autolytic amidase. The walls from the polar regions were found to turn over extensively.
Decay of Ribonucleic Acid Synthesis in Amino Acid-Starved
Escherichia coli
After Rifampin Treatment
Authors: Rogerson Allen C. , Ezekiel David H.
Published: January 2020

The concentration of rifampin necessary to affect the initiation of ribonucleic acid (RNA) synthesis quickly in
Escherichia coli
strains K-12 and 15TAU was about 200 μg/ml, as determined by extrapolation of the effect of the drug on the induction of β-galactosidase synthesis. A lag in the action of rifampin of about 10 s was confirmed. Rifampin was then used as a probe to compare RNA synthesis in growing and amino acid-starved
E. coli
. Restoring arginine to arginine-starved strain 15TAU immediately after rifampin inhibition did not detectably restore the rate of uracil uptake to that of uninhibited cells. The residual rate of RNA synthesis (corrected for acid-soluble triphosphate specific activities) after rifampin treatment of both growing and isoleucine-starved (valine-inhibited) cultures of strain K-12 showed similar decay kinetics. These findings support the notion that amino acid starvation blocks the initiation of some RNA transcription units, but do not rule out other possibilities.
Lipid Composition of the Zoospores of
Blastocladiella emersonii
Authors: Mills G. L. , Cantino E. C.
Published: January 2020

The zoospores of
Blastocladiella emersonii
, when derived from cultures grown on solid media, contain about 11% total lipid. This lipid was separated chromatographically on silicic acid into neutral lipid (46.6%), glycolipid (15.8%), and phospholipid (37.6%). Each class was fractionated further on columns of silicic acid, Florisil, or diethylaminoethyl-cellulose, and monitored by thin-layer chromatography. Triglycerides were the major neutral lipids, mono- and diglycosyldiglycerides were the major glycolipids, and phosphatidylcholine and phosphatidylethanolamine were the major phospholipids. Other neutral lipids and phospholipids detected were: hydrocarbons, free fatty acids, free sterols, sterol esters, diglycerides, monoglycerides, lysophosphatidylcholine, lysophosphatidylethanolamine, phosphatidic acid, phosphatidylserine, and phosphatidylinositol. Palmitic, palmitoleic, stearic, oleic, γ-linolenic, and arachidonic acids were the most frequently occurring fatty acids. When
B. emersonii
was grown in
14
C-labeled liquid media, lipid again accounted for 11% of both mature plants and zoospores released from them. The composition of the lipid extracted from such plants and spores was also the same; however, it differed markedly from that of the lipid in spores harvested from solid media, consisting of 28.3% neutral lipid, 12.0% glycolipid, and 59.7% phospholipid. The major lipids were again triglycerides for neutral lipids, mono- and diglycosyldiglycerides for glycolipids, and phosphatidyl choline and phosphatidylethanolamine for phospholipids.
Analysis of the Growth of Recombination-Deficient Strains of
Escherichia coli
K-12
Authors: Capaldo Florence N. , Ramsey Glenn , Barbour Stephen D.
Published: January 2020

Cultures of recombination-deficient strains of
Escherichia coli
are composed of three classes of cells: (i) viable cells, which can undergo 20 or more generations, (ii) residually dividing cells, which can undergo fewer than 20 generations (probably an average of fewer than 6), and (iii) nondividing cells, which are incapable of a single division. The nonviable but residually dividing cells contribute to the mass increase of the culture, but not to the viability, thus accounting for the apparent dissimilarity in the effects of
rec
mutations on growth rates and viabilities. We have determined the frequencies of cells in each of the three classes, and, by making a simplifying assumption concerning the relative division times of viable and residually dividing cells, we have been able to describe mathematically the growth of the
rec
−
cultures.
Morphological Study of
Streptococcus mutans
and Two Extracellular Polysaccharide Mutants
Authors: Johnson M. C. , Bozzola J. J. , Shechmeister I. L.
Published: January 2020

Two extracellular polysaccharide mutants of
Streptococcus mutans
GS-5 were obtained and examined. The mutants were distinguished by colonial morphology and by growth on and adherence to hard surfaces. A technique was devised which allowed these bacteria to be studied as they appeared when grown on a hard surface in liquid medium which contained sucrose. Negative stains, replicas, and scanning electron micrography clearly revealed differences in cellular aggregation due to the various extracellular polysaccharides produced. Comparison of sections of the adherent parent strain (GS-5) with those of the nonadherent mutant (GS-511) allowed the extracellular polysaccharide(s) responsible for adhesion to be visually localized.
Inhibition of Thiamine Pyrophosphate Utilization by Thiamine or Its Monophosphate in
Escherichia coli
Authors: Nakayama Hideo , Hayashi Ryoji
Published: January 2020

The growth of a thiamine pyrophosphate auxotroph of
Escherichi coli
was inhibited by either thiamine or thiamine monophosphate, and the growth of a thiamine monophosphate auxotroph was inhibited by thiamine. The thiamine pyrophosphate-dependent oxidation of pyruvate was inhibited by thiamine with whole cells of the thiamine pyrophosphate auxotroph but not with cell extracts prepared from the same organism. In addition, the thiamine pyrophosphate uptake of the thiamine pyrophosphate auxotroph was inhibited by either thiamine or thiamine monophosphate. Although the thiamine pyrophosphate uptake of a revertant, selected for prototrophy from the thiamine monophosphate auxotroph, was inhibited by thiamine to an extent comparable to that observed with the thiamine monophosphate auxotroph, its growth was no longer inhibited by thiamine. A possible mechanism for the inhibition by thiamine and thiamine monophosphate in the utilization of thiamine pyrophosphate is discussed.
Substrate Specificity of the Purified Primary Alcohol Dehydrogenases from Methanol-Oxidizing Bacteria
Authors: Sperl George T. , Forrest Hugh S. , Gibson David T.
Published: January 2020

Hyphomicrobium
strain WC,
Pseudomonas
strain TP-1, and
Pseudomonas
strain W1 are capable of growth on methanol as the sole source of carbon and energy. Methanol-grown cells of each organism contain a primary alcohol dehydrogenase that has been purified to homogeneity. Each enzyme has a molecular weight of 120,000 and shows an in vitro requirement for phenazine methosulfate and ammonium ions for enzymatic activity. Normal aliphatic alcohols are oxidized rapidly by each enzyme. The presence of a methyl group on the carbon atom adjacent to the primary alcohol group lowers the enzymatic activity. This effect is reduced as the methyl substituent is moved further away from the hydroxyl group. The effect of other substituents on enzymatic activity is reported. Methanol, formaldehyde, and to a limited extent acetaldehyde are oxidized by the primary alcohol dehydrogenases. Higher aldehydes are not oxidized. A possible explanation for this specificity, with regard to aldehydes, is presented in terms of degree of hydration of the aldehyde.
Role of Methionine in Bacterial Chemotaxis
Authors: Aswad Dana , Koshland D. E.
Published: January 2020

The effect of methionine starvation on the motility and behavior of normal and nonchemotactic mutants of
Salmonella typhimurium
was investigated. Methionine starvation eliminates tumbling in the wild type, but fails to do so in an uncoordinated (frequent tumbling) mutant. In the mutant, methionine starvation significantly extends the period of smooth motility that follows a sharp temporal increase of attractant. These results suggest that methionine metabolism is not tightly coupled to the generation of tumbles, but rather is necessary for the return of some tumble-regulating parameter to a steady-state level.
Mesosome Structure in
Chromobacterium violaceum
Authors: Rucinsky T. E. , Cota-Robles E. H.
Published: January 2020

Exponentially growing cells of the gram-negative bacterium
Chromobacterium violaceum
demonstrate invaginations of the cytoplasmic membrane with a high frequency. These invaginations conform to the ultrastructural appearance of mesosomes of gram-positive bacteria. As many as four mesosomes are observed per cell, each of which may increase the total membrane surface of the cell by 30%. Washing of cells in dilute tris(hydroxymethyl)aminomethane buffer effects a distension of the mesosome “neck” and/or cytoplasmic membrane clarifying the association of the mesosome to the cytoplasmic membrane. Plasmolysis effects an eversion of the mesosome into the plasmolysis vacuole.
Glucose Inhibition of the Transport and Phosphoenolpyruvate-Dependent Phosphorylation of Galactose and Fructose in
Vibrio cholerae
Authors: Bag Jnanankur
Published: January 2020

Vibrio cholerae
followed a two-step pattern of growth in a medium containing glucose and either galactose or fructose. Glucose was utilized first. Glucose inhibited the uptake and phosphenolpyruvate-dependent phosphorylation of galactose and fructose.
Mutants of
Escherichia coli
with Cold-Sensitive Deoxyribonucleic Acid Synthesis
Authors: Waskell Lucy , Glaser Donald A.
Published: January 2020

Ten cold-sensitive mutants defective in deoxyribonucleic acid (DNA) synthesis at 20 C have been identified among 218 cold-sensitive mutants isolated from a mutagenized population of
Escherichia coli
K-12. Four of the ten mutant alleles,
dna-339 dna-340, dna-341
, and
dna-342
, cotransduce with
serB
+
and hence may be
dnaC
mutants. Two of these,
dna-340
and
dna-341
, are recessive to their wild-type allele. The gene product of their wild-type allele is
trans
acting. Complementation tests have demonstrated that
dna-340
and
dna-341
are in the same cistron. The mapping of the remaining six mutations is in progress. In an attempt to determine whether LW4 and LW21 were initiator mutants, cultures of these strains were starved of an essential amino acid at 37 C and then incubated at 15 C with the essential amino acid. The amount of DNA synthesis observed under these circumstances was insignificant. These data are consistent with the idea that LW4 and LW21 are initiator mutants. However, attempts to integratively suppress LW4 and LW21 with F′ factors were unsuccessful. To resolve the question of whether or not LW4 and LW21 are initiator mutants, more specific tests and criteria are required. Cultures of LW4 and LW21 were toluene treated and used to measure in vitro DNA synthesis. If the cells were incubated either at 15 or 20 C before toluene treatment, they were capable of markedly less DNA synthesis than if preincubation had not occurred. The amount of in vitro DNA synthesis is directly proportional to the amount of DNA synthesis occurring during preincubation in vivo; i.e., more DNA synthesis is observed at 20 than at 15 C. The fact that the cold-sensitive mutants are unable to synthesize DNA when supplied with deoxyribonucleoside triphosphates, DNA precursors, is evidence they are not defective in precursor synthesis.
Identification and Mapping of the Replication Genes of an R Factor, R100-1, Integrated into the Chromosome of
Escherichia coli
K-12
Authors: Yoshikawa Masanosuke
Published: January 2020

A stable Hfr strain of
Escherichia coli
K-12 was obtained by integrative suppression by an R factor, R100-1. The R factor was integrated into the right of 81 min, and chromosome transfer occurred counterclockwise. Mating experiments revealed two linkage groups of genes on the R factor. Drug-resistant transductants of a
dnaA
-ts recipient from an R-factor Hfr and from an R
+
strain differ in their drug resistance patterns, temperature sensitivity, and transferability of drug resistance as well as chromosome markers. Transductants that transferred chromosome markers were further classified as to the origin and direction of chromosome transfer. For temperature-sensitive transductants, the reversion frequency to temperature resistance was determined, and these revertants were scored for transfer of drug resistance as well as chromosome markers. Two genes responsible for integrative suppression (designated as
repA
) and the other for autonomous replication (designated as
repB
) were identified and mapped. The arrangement of genes on the R factor is... (
sul, str, cml
)...
repA... tra
... (
tet, repB
).... The map of the autonomously replicating R factor is probably a circle connecting both sides of this linear map. Thus, a method has been established to map a plasmid that could not finely be analyzed under autonomous state by transduction. It also permits genetic analysis of genes responsible for replication of the plasmid without making use of a conditional mutant of itself but with that of the host,
dnaA
.
Heptose-Containing Pentaglycosyl Diglyceride Among the Lipids of
Acholeplasma modicum
Authors: Mayberry W. R. , Smith P. F. , Langworthy T. A.
Published: January 2020

A pentaglycosyl diglyceride with the tentative structure of galactosyl-galactosyl-mannoheptosyl-glucosyl-glucosyl diglyceride was found to be the major glycolipid in
Acholeplasma modicum
. The heptose is
d
-glycero-
d
-mannoheputose. The diglyceride-terminating moiety possesses the structure
O
-α-
d
-glucopyranosyl-(1 → 2)-
O
-α-
d
-glucopyranosyl-
sn
-1,2-diglyceride. Other glycolipids occurring in this organism are a diglucosyl diglyceride and a monoglucosyl diglyceride with structures identical to the terminal segments of the pentaglycosyl diglyceride. More fully acylated derivatives of these two glycolipids also occur. The phospholipids are all of the glycerophosphoryl type. The neutral lipids are composed of diglycerides and four polyterpenes. The polyterpenes consist of both colored and colorless carotenoids and become radiolabeled with both [
14
C]acetate and [
14
C]mevalonate.
Tests for Deoxyribonucleic Acid Synthesis in Toluenized
Bacillus subtilis
Cells
Authors: Matsushita Tatsuo , Sueoka Noboru
Published: January 2020

Several tests were devised to further characterize deoxyribonucleic acid (DNA) synthesis in toluenized
Bacillus subtilis
cells. Vigorous agitation of toluenized cells (localization test) demonstrated that the DNA replication is exclusively a cell-associated process. A DNA “repair” condition was also applied to toluenized cells and shown to be distinct from DNA replication in its DNA polymerase I dependency and its ability to synthesize DNA on template which is either cell associated or free, outside the cell. This repair condition was used in conjunction with the localization test to demonstrate the penetration of deoxyribonuclease I and possibly DNA polymerase I into toluenized cells. Therefore, we suggest that the localization test can be used to test the penetration of proteins into toluenized cells for both the DNA repair and replication processes.
Escherichia coli
Females Defective in Conjugation and in Adsorption of a Single-Stranded Deoxyribonucleic Acid Phage
Authors: Reiner Albey M.
Published: January 2020

We predicted that, among mutants resistant to infection by single-stranded deoxyribonucleic acid viruses, there would be some also resistant to “infection” by single-stranded conjugal deoxyribonucleic acid. Approximately 5% of the
Escherichia coli
K-12 females selected for resistance to phage ST-1 were defective as recipients in conjugation. These spontaneous mutants fell into two classes. Type A accepted both plasmid and chromosomal markers at greatly reduced frequencies (<10
−6
of normal for at least one strain), formed “rough” colonies, and (unlike their parent) were nonflagellated. Type B strains accepted both chromosomal and plasmid markers at reduced frequencies (10
−2
to 10
−1
of normal), were temperature sensitive for growth, and showed increased susceptibility towards antibiotics and deoxycholate. Both classes of mutants also were resistant to certain female-specific viruses.
Relationship Between [8-
14
C]Adenosine Transport and Growth Inhibition in
Neurospora crassa
Strain
ad-8
Authors: Magill Jane M. , Spencer Roberto R. , Magill Clint W.
Published: January 2020

The kinetic parameters of [8-
14
C]adenosine transport by a general nucleoside uptake system were studied in germinated conidia of the
ad 8
strain of
Neurospora crassa
. The apparent

K
m

for adenosine uptake by this system was found to be 6.2 μM. The apparent

K
i

values for other nucleosides competing with adenosine for uptake were measured by using Dixon plots. Nucleosides which were efficient competitive inhibitors of adenosine transport were found to inhibit severely the rate of growth of strain
ad-8
on adenosine-supplemented medium. Xanthosine and thymidine did not inhibit [8-
14
C]adenosine uptake as severely as other nucleosides, nor did they cause significant inhibition of
ad-8
growth rate on adenosine.
Macromolecular Composition During Steady-State Growth of
Escherichia coli
B/r
Authors: Dennis Patrick P. , Bremer Hans
Published: January 2020

By using
Escherichia coli
B/r, the cellular amounts of ribonucleic acid (RNA) and protein were determined as a function of the steady-state growth rate (0.67 to 2.40 doublings per h) by a method which combines measurements of the RNA to deoxyribonucleic acid (DNA) ratio and the differential rate of ribosomal protein synthesis with the Cooper and Helmstetter theory of DNA replication. The results indicate that the ratios RNA/DNA, RNA/protein, and protein/DNA give linear relationships with the growth rate (above 1.2 doublings per h), whereas RNA/cell and protein/cell show a more complex growth rate dependency. The significance of these relationships is discussed. Finally, a detailed description of the growth parameters and composition of
E. coli
B/r is presented.
R-Factor-Mediated β-Lactamases That Hydrolyze Oxacillin: Evidence for Two Distinct Groups
Authors: Dale J. W. , Smith J. T.
Published: January 2020

The enzymatic and molecular properties of 14 oxacillin-hydrolyzing β-lactamases, all of them R-factor-specified, were studied, and two distinct groups were found. Four of the enzymes had a molecular weight of 24,000, were active against methicillin, and had an electrophoretic mobility of −0.1 cm/h. Eight enzymes had a molecular weight of 45,000, low activity against methicillin, and an electrophoretic mobility of +0.5 cm/h. The remaining two enzymes were similar to those of the second group in being relatively inactive against methicillin, but their molecular weight was lower (42,000) and their electrophoretic mobility was different (−0.1 cm/h). All the enzymes of both groups were sensitive to inhibition by sodium chloride. The two groups were not completely homogeneous in their enzymatic properties; seven possible subtypes could be recognized.
Messenger Ribonucleic Acid of Dormant Spores of
Bacillus subtilis
Authors: Jeng Yun-Hua , Doi Roy H.
Published: January 2020

Evidence of the presence of messenger ribonucleic acid (mRNA) in dormant spores of
Bacillus subtilis
has been obtained. The bulk RNA from spores was isolated and labeled in vitro with tritiated dimethyl sulfate. The spore RNA hybridized to 2.4 to 3.2% of the
B. subtilis
genome. The RNA hybridized to both the complementary heavy and light fractions of deoxyribonucleic acid (DNA). Bulk RNA from log-phase cells competed with virtually all the spore RNA for the heavy DNA fraction and with part of the spore RNA for the light DNA fraction. Bulk RNA from stage IV cells in sporulation also competed with all of the spore RNA for the heavy DNA fraction and with essentially all the spore RNA for the light DNA fraction. These results indicate that dormant spores contain mRNA species present in both log-phase cells and stage IV cells of sporulation. The RNA polymerase in the developing forespore must be able to recognize promotor sites for both log-phase and sporulation genes.
Biogenesis of β-Carotene in
Mycobacterium kansasii
Authors: David Hugo L.
Published: January 2020

The biogenesis of β-carotene in the photochromogen
Mycobacterium kansasii
consists of two reactions. The first reaction is photochemical, and is dependent on the wavelength of the incident light and on oxygen but is independent of temperature. The second reaction does not require illumination, and is dependent on the temperature and on oxygen. The latter, or dark reaction, requires the synthesis of new protein, and was shown to have the characteristics of an inducible system. Carotenogenesis was stimulated by incident light of wavelengths of 420, 540, and 650 nm. Immediately after illumination there was an increase in the synthesis of ribonucleic acid and β-carotene accumulation started after a lag of 8 to 10 min. The synthesis of β-carotene exhibited temperature dependence with an optimum of about 36 C.
Macromolecule Synthesis and Breakdown in Relation to Sporulation and Meiosis in Yeast
Authors: Hopper Anita K. , Magee P. T. , Welch S. K. , Friedman M. , Hall B. D.
Published: January 2020

The time course of synthesis and breakdown of various macromolecules has been compared for sporulating (
a
/α) and nonsporulating (
a/a
and α/α) yeast cells transferred to potassium acetate sporulation medium. Both types of cells incorporate label into ribonucleic acid and protein. The gel electrophoresis patterns of proteins synthesized in sporulation medium are identical for sporulating and nonsporulating diploids; both are different from electropherograms of vegetative cells. Sporulating and nonsporulating strains differ with respect to deoxyribonucleic acid synthesis; no deoxyribonucleic acid is synthesized in the latter case, whereas the deoxyribonucleic acid complement is doubled in the former. Glycogen breakdown occurs only in sporulating strains. Breakdown of preexisting vegetative ribonucleic acid and protein molecules occurs much more extensively in sporulating than in nonsporulating cells. A timetable of these data is presented.
Electron Microscope Study of Septum Formation in
Escherichia coli
Strains B and B/r During Synchronous Growth
Authors: Burdett I. D. J. , Murray R. G. E.
Published: January 2020

The formation of cell wall septa was monitored in
Escherichia coli
B and B/r during synchronous growth in glucose media at 37 C by means of electron microscopy. The visible events of septation comprised the following sequence, starting at about 30 min of incubation: (a) bleb formation of the outer membrane; (b) invagination of mucopeptide and cytoplasmic membrane (with associated mesosomes); the outer membrane is excluded from the septum; (c) formation of a cross-wall; (d) ingrowth of the outer membrane during cell separation. The septum is composed of a fold of cytoplasmic membrane plus mucopeptide, and the latter is a double structure, composed of two opposed lamellae separated by an electron-transparent gap. Experiments with chloramphenicol and nalidixic acid suggested that division could occur in the presence of these inhibitors once a round of deoxyribonucleic acid replication is completed. The initial stages of septation, as estimated by the potential of the cells to produce bulges in the presence of ampicillin, may involve the modification of mucopeptide by hydrolases at the end of the C period. Assembly of the septum may occur during the first half of the D period by means of precursors synthesized during the preceding C period.
Detection of Selenium Deposits in
Escherichia coli
by Electron Microscopy
Authors: Gerrard T. L. , Telford J. N. , Williams H. H.
Published: January 2020

Cells of
Escherichia coli
will reduce sodium selenite to elemental selenium. Examination by electron microscopy of
E. coli
cultures grown in the presence of sodium selenite show selenium deposited on the cell membrane and cell wall but not in the cytoplasm.
Characterization of Lactose-Fermenting Revertants from Lactose-Negative
Streptococcus lactis
C2 Mutants
Authors: Cords B. R. , McKay L. L.
Published: January 2020

Partial lactose-fermenting revertants from lactose-negative (
lac
−
) mutants of
Streptococcus lactis
C2 appeared on a lawn of
lac
−
cells after 3 to 5 days of incubation at 25 C. The revertants grew slowly on lactose with a growth response similar to that for cryptic cells. In contrast to
lac
+
S. lactis
C2, the revertants were defective in the accumulation of [
14
C]thiomethyl-β-
d
-galactoside, indicating that they were devoid of a transport system. Hydrolysis of
o
-nitrophenyl-β-
d
-galactoside-6-phosphate by toluene-treated cells confirmed the presence of phospho-β-
d
-galactosidase (P-β-gal) in the revertant. However, this enzyme was induced only when the cells were grown in the presence of lactose; galactose was not an inducer. In
lac
+
S. lactis
C2, enzyme induction occurred in lactose- or galactose-grown cells. The revertants were defective in EII-lactose and FIII-lactose of the phosphoenolpyruvate-dependent phosphotransferase system. Galactokinase activity was detected in cell extracts of
lac
+
S. lactis
C2, but the activity was 9 to 13 times higher in extracts from the revertant and
lac
−
, respectively. This suggested that the
lac
−
and the revertants use the Leloir pathway for galactose metabolism and that galactose-1-phosphate rather than galactose-6-phosphate was being formed. This may explain why lactose, but not galactose, induced P-β-gal in the revertants. Because the revertant was unable to form galactose-6-phosphate, induction could not occur. This compound would be formed on hydrolysis of lactose phosphate. The data also indicate that galactose-6-phosphate may serve not only as an inducer of the lactose genes in
S. lactis
C2, but also as a repressor of the Leloir pathway for galactose metabolism.
Cross-Pathway Regulation: Tryptophan-Mediated Control of Histidine and Arginine Biosynthetic Enzymes in
Neurospora crassa
Authors: Carsiotis M. , Jones Richard F.
Published: January 2020

In
Neurospora crassa
, the starvation of tryptophan mutants for tryptophan resulted in the derepression of tryptophan, histidine, and arginine biosynthetic enzymes. This tryptophan-mediated derepression of histidine and arginine biosynthetic enzymes occurred despite the fact that the tryptophan-starved cells had a higher intracellular concentration of histidine and arginine than did nonstarved cells.
Streptococcus mutans
Dextransucrase: Requirement for Primer Dextran
Authors: Germaine Greg R. , Chludzinski Andrew M. , Schachtele Charles F.
Published: January 2020

Dextran stimulation (priming) of the dextransucrase (EC 2.4.1.5) from
Streptococcus mutans
strain 6715 was studied. The dextransucrase activity in supernatant fluids from glucose-grown cultures was shown to be partially primer dependent. During extended storage at 4 C the enzyme retained its activity. However, the ability to make dextran became increasingly primer dependent. Hydroxylapatite-chromatographed enzyme preparations were completely dependent upon added dextran for rapid synthesis of methanol-insoluble glucan from sucrose. Half-maximal stimulation of new dextran synthesis occurred with dextran at a concentration of 2 to 3 μM and with a molecular weight of about 2,600. Neither glycogen, amylose, inulin, nor isomaltose functioned as primer. Studies with the dextransucrase activities detectable by in situ assay in polyacrylamide gels subjected to electrophoresis under nondenaturing conditions revealed that the major activity was detectable in the presence of sucrose alone and was stimulated by addition of primer dextran. The minor activity was only detected when primer dextran was present. Homogeneous preparations of both enzymes contained 30 to 40% carbohydrate.
First Enzyme of Histidine Biosynthesis and Repression Control of Histidyl-Transfer Ribonucleic Acid Synthetase of
Salmonella typhimurium
Authors: Coleman W. G. , Williams L. S.
Published: January 2020

The regulation of formation of histidyl-transfer ribonucleic acid (tRNA) synthetase was examined in strains of
Salmonella typhimurium
. When the first of the histidine-forming enzymes was wild type, the presence of 2-thiazolealanine in the growth medium prevented repression of histidyl-tRNA synthetase formation elicited by the addition of 1, 2, 4-triazole-3-alanine to these cultures. Conversely, thiazolealanine had no effect on repression of histidyl-tRNA synthetase formation by triazolealanine in
hisG
mutant strains. These data suggest a relationship between the control of histidyl-tRNA synthetase formation and the functional state of the histidine operon.
Macromolecular Structure and Morphology of Native Glycogen Particles Isolated from
Candida albicans
Authors: Yamaguchi Hideyo , Kanda Yayoi , Iwata Kazuo
Published: January 2020

A polysaccharide-rich particulate fraction was isolated from cytoplasmic extracts of
Candida albicans
by a procedure using differential centrifugation. The polysaccharide particles obtained after purification with deoxycholate treatment were essentially free of nitrogen and were identified chemically as polyglucosan, in which the glucosidic links were of alpha type. Both the response to amylolytic enzymes and the spectral characteristics of the iodine complexes of the polysaccharide particles were similar to those of rabbit liver glycogen. They also precipitated with concanavalin A, the glycogen value being assessed at 1.04. These data strongly indicated that the polysaccharide particles have the macromolecular structure characteristic of glycogen. The sedimentation analysis revealed that they were polydisperse, with a weight average sedimentation coefficient of 340
S
. In negatively stained specimens, the glycogen particles were seen to form rosette-like structures consisting of a complex unit 40 to 150 nm in diameter. Such complex particles were composed of smaller globules that were fairly uniform in size with an average diameter of 32 nm.
Chemotaxis in
Bdellovibrio bacteriovorus
Authors: Straley Susan C. , Conti S. F.
Published: January 2020

Chemotaxis toward yeast extract is demonstrated in obligately and facultatively parasitic strains of
Bdellovibrio bacteriovorus
.
In Vivo Kinetics of Nitrogenase Formation inClostridium pasteurianum
Authors: Seto Belinda , Mortenson L. E.
Published: January 2020

Clostridium pasteurianumexhibits diauxic growth when grown in the presence of both NH3and N2; no nitrogenase activity or formation was detected either serologically or by activity during growth on NH3. During the 60-min lag that ensued after NH3was consumed and before growth resumed, molybdoferredoxin and azoferredoxin were first detected by activity measurements and serologically at 25 and 40 min, respectively. With the use of rifampin and dactinomycin, it was found that azoferredoxin messenger ribonucleic acid was initiated between 25 and 30 min after the inception of the lag and was completed by 38 min. An explanation of these results and their relation to possible models for the regulation of nitrogenase is given.
Curing Action of Sodium Dodecyl Sulfate on a
Proteus mirabilis
R
+
Strain
Authors: Tomoeda Munemitsu , Inuzuka Manabu , Anto Shizuko , Konishi Mariko
Published: January 2020

Growth of
Proteus mirabilis
harboring R100-1 (
fi
+
drd str
r
cml
r
tet
r
sul
r
) factors in Penassay broth containing sodium dodecyl sulfate (SDS) leads to the loss of all or part of the genetic elements in high frequencies. In media containing SDS at concentrations as low as 0.03%, both lysis of R
+
cells and elimination of the R factors occur at high frequencies. Appearance of drug-susceptible cells in R
+
cultures occurs during the exponential phase of growth; however, the frequencies of susceptible cells increase substantially after the culture reaches the stationary phase. Reconstruction experiments, coupled with other observations, suggest that the major factor in altering the frequency of drug-susceptible variants is the greater resistance of the variants to the lytic action of SDS. This resistance correlates in most cases with the loss of the transfer functions in the resistance transfer factor.
Lipids of the
Spirochaetales
: Comparison of the Lipids of Several Members of the Genera
Spirochaeta, Treponema
, and
Leptospira
Authors: Livermore Brian P. , Johnson Russell C.
Published: January 2020

The lipid compositions of 17 spirochetes belonging to the genera
Spirochaeta
and
Treponema
were investigated and compared with data previously derived from 11 strains of
Leptospira
. The lipid compositions and lipid metabolism of any of these genera is sufficiently different to be characteristic of that genus and to differentiate it from the other two genera. Members of the genus
Leptospira
are characterized by their ability to beta-oxidize long chain fatty acids as their major carbon and energy source. With few exceptions, they are incapable of synthesizing fatty acids de novo. The major phospholipid found was phosphatidyl ethanolamine. No glycolipid or phosphatidyl choline was found in these organisms. Members of the genus
Treponema
studied were incapable of beta-oxidation as well as de novo synthesis of fatty acids. Phosphatidyl choline is the major phospholipid of this genus. The glycolipid, monogalactosyl diglyceride, is a major component of the
Treponema
. Members of the
Spirochaeta
did synthesize fatty acids de novo. Although these spirochetes contain a monoglycosyl diglyceride, the hexose content of the glycolipid varied from species to species. Neither phosphatidyl ethanolamine nor phosphatidyl choline was found in the
Spirochaeta
.
Cell Division in
Escherichia coli
: Analysis of Double Mutants for Filamentation and Abnormal Septation of Deoxyribonucleic Acid-Less Cells
Authors: Zusman David R. , Krotoski Danuta M.
Published: January 2020

The link between chromosome termination, initiation of cell division, and choice of division sites was studied in
Escherichia coli
by preparing double mutants. Hybrid mutants containing
div52-ts
, a cell division initiation mutation, and
min
, mutations which affect the choice of division sites resulting in the septation of minicells, were characterized. The mutants produced minicells and normal cells coordinately under all conditions studied, although the fraction of minicells is half that of the parental minicell strain. The mutant gradually stopped dividing at both the median and minicell septation sites when transferred from 30 to 41 C in rich medium. A synchronous cell division of filaments was induced 15 min after addition of chloramphenicol to the medium, even at 41 C. Divisions were observed at both normal and minicell sites. These results indicate that
div52-ts
and
min
functions share a common step in a cell division pathway. A double mutant containing
div52-ts
and
div27-ts
, a
dnaB
mutant which divides in the absence of DNA synthesis, was characterized. The mutant continues to divide after a shift to the high temperature, although at a reduced rate. The behavior of this hybrid mutant suggests a hypothesis that the chromosome termination signal and
div52-ts
division initiation signal act on a single membrane site which is altered in
div27-ts
strains.
Scanning Electron Microscopy of
Thermoplasma acidophilum
Authors: Mayberry-Carson K. J. , Roth Ivan L. , Harris James L. , Smith Paul F.
Published: January 2020

The scanning electron microscope was utilized to observe the morphology of the thermophilic, acidophilic mycoplasma,
Thermoplasma acidophilum
. Upon examination of the surface morphology, the size and shape of this unusual mycoplasma revealed its similarity to the other mycoplasmas that have been investigated.
Multiple mutations in cysA 14 MUTANTS OF Bacillus subtilis
Authors: Kane J F , Goode R L , Wainscott J
Published: January 2020

Isolates of Bacillus subtilis that had been presumed to carry the cysA14 lesion have been studied. Our data indicate that these strains contain four mutations, all of which are linked by transformation and lie in the region of the ribosomal markers. The requirement for cysteine results from a defective serine transacetylase that is coded for by the cysA locus. Therefore, these mutants grow only in the presence of cysteine but not with sulfate, sulfite, or sulfide as the sole source of sulfur. A second genetic lesion (css) can be recognized by an increased sensitivity to the amino acid L-cysteine. The inhibited enzyme(s) has not been determined but inhibition is overcome by a mixture of eight amino acids. The third mutation (hts) results in the overproduction and excretion of hydrogen sulfide. This compound appears to be produced from cysteine by the enzyme cysteine desulfhydrylase and not by an increased activity of the sulfate-reductive pathway. This locus presumably codes for a regulatory element involved in the control of cysteine desulfhydrylase. The fourth mutation (cym) is not well characterized biochemically but results in a requirement for cysteine or methionine. The following order of these mutations has been established by transformation studies: hts, cysA, css, cym. The generally poor growth of these mutants in minimal-salts glucose media supplemented with cysteine can now be explained by these observations. The cysA14 mutants not only require an amino acid that is itself inhibitory to growth but they also overproduce the highly toxic compound hydrogen sulfide.