bluuebunny/crossref_metadata_2025 huggingface dataset:
Competence Mutants III. Responses to Radiations
Authors: Postel Edith Horn , Goodgal Sol H.
Published: January 2020

Class 3
com
−
mutants [normal in deoxyribonucleic acid (DNA) uptake but poor in ability to transform] were investigated with regard to ultraviolet (UV) and X-ray sensitivity of colony-forming ability and with regard to their ability to be transformed by UV- and X-ray-irradiated DNA. Three mutants,
com
−
40, 60, and 78, were highly UV-sensitive in colony-forming ability. None of the mutants was more sensitive than wild type to UV-irradiated transforming DNA; in fact, six of the mutants showed considerably greater resistance. Two of the mutants (
com
−
40 and 60) were slightly more sensitive to X ray in colony formation, whereas most of the mutants showed some degree of sensitivity to X-ray-irradiated transforming DNA. In addition, the physical fate of X-ray-irradiated transforming DNA has been examined, and in one case (
com
−
48) there was a significant drop in sedimentation value of X-ray-irradiated donor DNA after uptake by recipient cells. The
com
−
mutants analyzed have been classified on the basis of their UV and X-ray sensitivities, and, where appropriate, possible biochemical lesions have been implicated.
Mode of Cell Wall Growth of
Bacillus megaterium
Authors: Mauck J. , Chan L. , Glaser L. , Williamson J.
Published: January 2020

The growth of the cell wall of
Bacillus megaterium
KM was examined by labeling the cell wall uniformly with
3
H-α, ε-diaminopimelic acid and examining by radioautography the distribution of labeled cell wall material in daughter cells. The results indicate that the label is distributed uniformly to all daughter cells and rule out a single growth point, either central or apical, for these cells. The results strongly suggest that cell wall growth occurs by uniform deposition of new wall over the whole cell surface.
Gene Frequency Analysis of Chromosomal Initiation Sites in
Bacillus subtilis
after Ultraviolet Light or X-Ray Exposure
Authors: Billen Daniel , Hellerman Gary , Carreira Laura
Published: January 2020

Bacillus subtilis
was exposed to ultraviolet light (UV) or X rays, and gene frequency analysis was used to study the location of initiation sites of postirradiation deoxyribonucleic acid (DNA) synthesis. It was found that DNA synthesis resumes primarily from the origin after UV exposure. With X irradiation, the origin is not selectively replicated. Elevated origin-to-terminal marker ratios observed after UV exposure of exponentially growing cells were interpreted as evidence for selective UV resistance of the replicative origin region of the bacterial chromosome.
Some Properties of Two Autolytic-Defective Mutants of
Streptococcus faecalis
ATCC 9790
Authors: Pooley H. M. , Shockman G. D. , Higgins M. L. , Porres-Juan J.
Published: January 2020

The isolation and some properties of two mutants of
Streptococcus faecalis
ATCC 9790 (
S. faecium
) which autolyze at a much slower rate than the wild type are described. Compared with the wild type, mutant E71 autolyzed more slowly, contained less active but more latent autolysin in the isolated wall fraction, and possessed a wall of very similar chemical composition and degree of cross-bridging. Ultrastructural studies of exponential phase cells showed that cells of E71 were on the average slightly longer and had slightly thickened walls compared to the wild type. Mutant E81 autolyzed much more slowly, grew exponentially in long chains (8 to 40 cells compared with mainly diplococci), contained much less active and latent autolysin in the wall, and possessed a wall of very similar chemical composition but with about twice the content of
N
-terminal groups. Mutant E81 walls were more susceptible to isolated autolysin but possessed an autolysin of the same specificity as the wild type. Ultrastructurally E81 cells were, on the average, significantly longer and had thicker walls than the wild type. Mutant E71 may be partially blocked at either transport of autolysin to the wall or in conversion of latent to active autolysin. The pleitropic effects noted in mutant E81 have been taken to suggest a possible membrane defect and to support the role of the autolysin in cell separation.
Fermentation of Agmatine in
Streptococcus faecalis:
Occurrence of Putrescine Transcarbamoylase
Authors: Roon Robert J. , Barker H. A.
Published: January 2020

Putrescine transcarbamoylase, EC 2.1.3.x (carbamoylphosphate:putrescine transcarbamoylase), has been purified from
Streptococcus faecalis
10C1 grown on agmatine as primary energy source. The formation of
N
-carbamoylputrescine from putrescine and carbamoylphosphate serves as a convenient and sensitive assay for this enzymatic activity. The enzyme catalyzes both the phosphorolysis arsenolysis of
N
-carbamoylputrescine. Arginine does not induce the synthesis of putrescine transcarbamoylase in
S. faecalis
. Furthermore, the putrescine transcarbamoylase activity is easily separated from ornithine transcarbamoylase activity by gel filtration on Sephadex G-100 indicating that the two activities are associated with different proteins. The significance of this new enzyme in the fermentation of agmatine and its relation to the other known transcarbamoylases are discussed.
Temperature Dependence of Sex-Factor Maintenance in
Escherichia coli
K-12
Authors: Stadler J. , Adelberg E. A.
Published: January 2020

Wild-type sex factors of
Escherichia coli
K-12 can be cured from host cells by growth at temperatures above 42 C. This phenomenon is obscured by reinfection of cured cells if the culture is allowed to reach cell densities above 10
5
/ml. The rate of episome loss is dependent on the genetic (chromosomal) background of the host.
Nucleic Acid and Protein Synthesis During Thymineless Death in Lysogenic and Nonlysogenic Thymine Auxotrophs
Authors: Medoff Gerald
Published: January 2020

Thymine deprivation causes the non-phage-associated component of thymineless death in
Escherichia coli
15T
−
. Addition of thymine causes the phage-associated component to occur.
Escherichia coli
Tryptophanase in the Enteric Environment
Authors: Botsford James L. , Demoss R. D.
Published: January 2020

The activity of the enzyme tryptophanase in the enteric environment was investigated to elucidate the significance of the enzyme in the metabolism of
Escherichia coli
. The tryptophanase activity, tryptophan content, and indole concentration as well as the numbers of
E. coli
were determined in the intestinal and fecal contents of conventional, germ-free, and monocontaminated axenic laboratory mice. Increasing the tryptophan content of the diet of mice having a conventional microflora increased the tryptophanase activity of the enteric microflora by a factor of almost 2 but did not increase the numbers of
E. coli
either absolutely or relative to other facultative enteric coliforms. In the enteric environment,
E. coli
is responsible for very little tryptophanase activity, a fraction calculated to be less than 0.02%. The values for the experimental parameters were much the same in the contents of the cecum and in the fecal material.
Role of Histidine Transfer Ribonucleic Acid in Regulation of Synthesis of Histidyl-Transfer Ribonucleic Acid Synthetase of
Salmonella typhimurium
Authors: McGinnis E. , Williams L. S.
Published: January 2020

The role of histidine transfer ribonucleic acid (tRNA) in repression of synthesis of histidyl-tRNA synthetase was examined in two strains of
Salmonella typhimurium
, one of which was a histidine tRNA (
hisR
) mutant possessing 52% of the wild-type (
hisR
+
) histidine tRNA and a derepressed level of the histidine biosynthetic enzymes during histidine-unrestricted growth. Histidine-restricted growth caused a derepression of the rate of formation of histidyl-tRNA synthetase in both strains. In the case of the wild-type strain, addition of histidine to the derepressed culture caused a repression of synthesis of histidyl-tRNA synthetase for at least one generation of growth. In contrast, when histidine was restored to the derepressed
hisR
mutant culture, synthesis of histidyl-tRNA synthetase was continued at the initial derepressed rate. These results suggest that histidine must be attached to histidine tRNA for repression of synthesis of histidyl-tRNA synthetase.
Characteristics of S Organism Isolated from
Methanobacillus omelianskii
Authors: Reddy C. Adinarayana , Bryant M. P. , Wolin M. J.
Published: January 2020

Previous work showed that
Methanobacillus omelianskii
was a mixed culture of an ethanol-oxidizing organism called S organism and a hydrogen-utilizing methane bacterium, strain MOH. S organism grows poorly on ethanol unless a hydrogen-utilizing methanogenic bacterium is included to utilize the H
2
produced during growth. Further studies have shown that, among many substrates tested, only ethanol,
n
-propanol,
n
-butanol, isobutanol,
n
-pentanol, acetaldehyde, oxalacetate, and pyruvate are fermented by S organism, either alone or in combination with
Methanobacterium ruminantium
. It grew better in pure culture with pyruvate than with alcohols. H
2
gas phase inhibited growth on pyruvate as well as on alcohol. When grown alone on pyruvate, S organism produced mainly acetate, ethanol, and CO
2
, in addition to a small amount of H
2
. When combined with
M. ruminantium
, no H
2
and very little ethanol were produced and acetate production was increased. When
M. ruminantium
was present, electrons from pyruvate oxidation by S organism were channeled almost entirely to H
2
and hence to methane formation rather than ethanol. Also, S organism utilized more pyruvate when grown with
M. ruminantium
. Attempts to obtain better growth of S organism on ethanol by addition of many possible electron acceptors were unsuccessful. It grew best between 32 and 45 C, had a per cent guanine plus cytosine content of deoxyribonucleic acid bases of 47.27 ± 0.1, contained no cytochrome, and could be grown on a defined medium with pyruvate as the energy and carbon source and with (NH
4
)
2
SO
4
as the main nitrogen source. These and other results suggest that S organism belongs in a new genus, but assignment of a definite taxonomic status should await isolation and characterization of more strains.
Leucyl-Transfer Ribonucleic Acid Synthetase from a Wild-Type and Temperature-Sensitive Mutant of
Salmonella typhimurium
Authors: Mikulka T. W. , Stieglitz B. I. , Calvo J. M.
Published: January 2020

Leucyl-transfer ribonucleic acid (tRNA) synthetase was purified 100-fold from extracts of
Salmonella typhimurium
. The partially purified enzyme had the following
K
m
values: leucine, 1.1 × 10
−5
m
; adenosine triphosphate, 6.5 × 10
−4
m
; tRNA
I
Leu
, 4.1 × 10
−8
m
; tRNA
II
Leu
, 4.3 × 10
−8
m
; tRNA
III
Leu
, 5.3 × 10
−8
m
; and tRNA
IV
Leu
, 2.9 × 10
−8
m
. The tRNA
Leu
fractions were isolated from Salmonella bulk tRNA by chromatography on reversed-phase columns and benzoylated diethylaminoethyl cellulose. The enzyme had a
p
H optimum of 8.5 and an activation energy of 10,400 cal per mole, and was inactivated exponentially at 49.5 C with a first-order rate constant of 0.064 min
−1
. Strain CV356 (
leuS3 leuABCD702 ara-9 gal-205
) was isolated as a mutant resistant to
dl
-4-azaleucine and able to grow at 27 C but not at 37 C. Extracts of strain CV356 had no leucyl-tRNA synthetase activity (charging assay) when assayed at 27 or 37 C. Temperature sensitivity and enzyme deficiency were caused by mutation in the structural gene locus specifying leucyl-tRNA synthetase. A prototrophic derivative of strain CV356 (CV357) excreted branched-chain amino acids and had high pathway-specific enzyme levels when grown at temperatures where its doubling time was near normal. At growth-restricting temperatures, both amino acid excretion and enzyme levels were further elevated. The properties of strain CV357 indicate that there is only a single leucyl-tRNA synthetase in
S. typhimurium
.
Method for Restricting Incorporation of Radioactivity from
3
H-Thymidine into Deoxyribonucleic Acid Only During Outgrowth of Spores of
Bacillus cereus
T
Authors: Rana Rajendra S. , Halvorson Harlyn O.
Published: January 2020

When heat-activated spores of
Bacillus cereus
T (
thy
−
) were germinated and grown in medium containing
3
H-thymidine, a significant amount of radioactivity was incorporated into ribonucleic acid and deoxyribonucleic acid (DNA). A method was developed to restrict the incorporation of radioactivity from
3
H-thymidine into DNA only. This was accomplished by labeling the cells with
3
H-thymidine in the presence of 2 mg of 2-deoxyadenosine per ml, 250 μg each of uracil, cytosine, and guanosine per ml, and 500 μg of adenosine per ml. Under these conditions, 97% of the radioactivity incorporated into cold trichloroacetic acid-insoluble material was associated with DNA only. In the absence of these compounds, DNA contained only 72% of the total radioactivity incorporated into cold acid-insoluble material.
Deoxyribonucleic Acid Relationships Among Marine Vibrios
Authors: Anderson Robert S. , Ordal Erling J.
Published: January 2020

The deoxyribonucleic acid (DNA) relationships of 80 strains identified either as
Vibrio parahaemolyticus, V. alginolyticus
, and
V. anguillarum
, or as allied marine vibrios were delineated by DNA-DNA competition experiments as well as by measuring the thermal stabilities of the DNA-DNA duplexes formed in direct binding studies. The tested strains included isolates from Japan, Europe, and the United States. The
V. parahaemolyticus
and
V. alginolyticus
groups showed an average of 67% homology to one another and 30% to strains of
V. anguillarum
. Significantly, a number of the isolates from the Pacific Northwest which had been previously identified as
V. parahaemolyticus
based on morphological, biochemical, and serological evidence were shown either to be strains of
V. anguillarum
or to belong to as yet unnamed groups. Most strains isolated from diseased salmon in the Pacific Northwest proved to be virtually identical with
V. anguillarum
type C by DNA homology experiments, thereby differentiating them from similar strains isolated from diseased herring and occasionally from salmon. The latter Pacific Northwest isolates fell into two distinct genotypic groups. A plot of the per cent homology by competition versus the difference in the thermal stabilities of heterologous and homologous duplexes (ΔT
m,e
) between the same DNA species shows a linear decline in homology of 4.25% per degree of ΔT
m,e
. The use of this relationship for estimating the percentage of the mispaired bases distinguishing DNA preparations directly from competition experiments is discussed.
Role of Metabolic Energy in the Transport of β-Galactosides by
Streptococcus lactis
Authors: Kashket E. R. , Wilson T. H.
Published: January 2020

Streptococcus lactis
(ATCC 7962) accumulated thiomethyl-β-galactoside (TMG) and other galactosides against concentration gradients when the cells were supplied with a metabolizable substrate, such as glucose. The accumulated TMG was free and not phosphorylated. In the absence of glucose, TMG rapidly entered the cell to a concentration equal to that of the medium. Agents that uncouple oxidative phosphorylation abolished active transport but not the carrier-facilitated entry of TMG. Evidence that the transport carriers were functional in the absence of glucose or in the presence of uncoupling agents included the demonstration of counterflow, which depends on competitive inhibition for the carrier for exit.
Characterization of Insoluble Protein Fractions of Mitochondria from
Saccharomyces cerevisiae
Authors: Fiechter A. , Mian F. A. , Ris H. , Halvorson H. O.
Published: January 2020

Saccharomyces cerevisiae
was grown in a chemostat in the presence of excess oxygen. Cells harvested from fully derepressed and strongly repressed steady states show typical promitochondria-like structures under conditions of strong repression. Insoluble membrane proteins were extracted from highly purified mitochondria and submitted to isoelectric focusing in 6% polyacrylamide gels. Some 20 protein bands were obtained from derepressed cells. The pattern was clearly different (quantitatively and possibly qualitatively) from repressed mitochondria. In contrast to ribosomal proteins, insoluble membrane protein fractions were found in the acid section (
p
H 4 to 6.8) of the ampholyte gels. It can be concluded that glucose repression plays a prominent role in the synthesis of the functional mitochondrial membranes.
Isolation, Characterization, and Ultrastructure of the Peptidoglycan Layer of a Marine Pseudomonad
Authors: Forsberg C. W. , Rayman M. Khalil , Costerton J. W. , MacLeod Robert A.
Published: January 2020

The peptidoglycan layer of a marine pseudomonad was observed by electron microscopy in thin sections of plasmolyzed intact cells and mureinoplasts but not in untreated intact cells. Only fragments of this layer could be isolated by sodium lauryl sulfate (SLS) treatment of mureinoplast envelopes. Sacculus-like peptidoglycan structures were obtained from growing cells by immediate heat inactivation of cellular autolytic enzymes and subsequent SLS, trypsin, and nuclease treatments. Recently, similar peptidoglycan sacculus-like structures have been obtained by adding SLS to the growing culture and treating the isolated particulate material with nucleases. Thin-sectioned and negatively stained preparations of whole cell peptidoglycan showed compressed profiles of cell-shaped sacculi. Peptidoglycan prepared by SLS treatment of mureinoplast envelopes had a similar composition to that prepared from whole cells. The major amino sugars and amino acids in the peptidoglycan component were glucosamine, muramic acid, alanine, glutamic acid and diaminopimelic acid in the molar ratios 1.18:1.24:1.77:1.00:0.79. Forty-five per cent of the ε-amino groups of diaminopimelic acid were cross-linked. The peptidoglycan was estimated to account for about 1% of the cell dry weight.
Biosynthesis of Thiamine Pyrophosphate in
Escherichia coli
Authors: Nakayama Hideo , Hayashi Ryoji
Published: January 2020

In
Escherichia coli
, thiamine pyrophosphate is synthesized from thiamine monophosphate. Free thiamine is not involved as an intermediate in de novo synthesis of thiamine pyrophosphate.
p
-Toluenethiol as an Initiator of Autolysis in Bakers' Yeast
Authors: Arnold Wilfred N.
Published: January 2020

Cysteine or dithiothreitol enhances the rate of autolysis in toluene-treated yeast.
p
-Toluenethiol alone is even more effective and is recommended for the isolation of β-fructofuranosidase. This suggests a more general application of
p
-toluenethiol in the isolation of enzymes from yeast.
Inhibition and Activation of Bacterial Luciferase Synthesis
Authors: Eberhard Anatol
Published: January 2020

Luciferase synthesis is repressed when bioluminescent bacteria are inoculated into fresh medium but is induced after the cells have grown in the medium for some time. In minimal medium, an activator which leads to induction of the enzyme is released into the medium by the bacteria. Complete medium contains a dialyzable and quite stable inhibitor which leads to repression of luciferase. The bacteria remove the inhibitor from the medium and also produce activator, thus allowing synthesis of the enzyme. Two unidentified nonluminescent strains of bacteria were unable to remove the inhibitor. Two different bioluminescent strains,
Photobacterium fischeri
and
P. fischeri
strain MAV, produce specific activators that are ineffective with cells of the other strain. The two activators are different with respect to heat stability, but both are small molecules. The activators can be assayed on the basis of their ability to counteract the inhibitor. Identification of the inhibitor and the activators may allow the bioluminescent system to be linked to other metabolic processes of the cells.
Morphokinetic Reaction of
Streptococcus faecalis
(ATCC 9790) Cells to the Specific Inhibition of Macromolecular Synthesis: Nucleoid Condensation on the Inhibition of Protein Synthesis
Authors: Daneo-Moore Lolita , Higgins Michael L.
Published: January 2020

In glutaraldehyde-prefixed exponential-phase cells of
Streptococcus faecalis
the nucleoid is “frozen” in a dispersed configuration. Exposure of exponential-phase cells to threonine starvation or to antibiotics inhibiting protein synthesis resulted in progressive condensation of nucleoid fibrils producing an expanding central nucleoid zone or pool. The condensation of the nucleoid was observed to occur at a rate directly proportional to the rate of inhibition of protein synthesis. However, the extent of nucleoid condensation depended on continuing deoxyribonucleic acid synthesis. Significantly less nucleoid condensation occurred when cells were inhibited in deoxyribonucleic acid and protein synthesis than when cells were inhibited in protein synthesis alone. These results suggest a model in which, during nucleoid replication, the chromosome fibrils are normally maintained in a dispersed state by the active agents of transcription-translation, such as ribonucleic acid polymerase molecules and ribosomes.
Fixation of Mature Spores of
Clostridium botulinum
Authors: Stevenson Kenneth E. , Vaughn Reese H. , Crisan Eli V.
Published: January 2020

A triple fixation method using a sequential application of 15 or 30% formaldehyde, 6% glutaraldehyde, and 1% osmium tetroxide resulted in excellent fixation of mature spores of
Clostridium botulinum
.
Photoreactivation and Gene Dosage in Yeast
Authors: Resnick Michael A. , Setlow Jane K.
Published: January 2020

The amount of photoreactivating enzyme in tetraploid cells of
Saccharomyces cerevisiae
and the ability of the cells to be photoreactivated after ultraviolet irradiation are directly proportional to the number of genes per cell involved in the synthesis of photoreactivating enzyme.
Ribosomal Proteins of
Rhodopseudomonas palustris
Authors: Bhatnagar Y. M. , Stachow C. S.
Published: January 2020

Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of ribosomal proteins of
Rhodopseudomonas palustris
revealed that the 29
S
subunit lacked a high-molecular-weight protein. It is suggested that a high-molecular-weight protein may function in protecting ribosomal ribonucleic acid from ribonuclease degradation.
Identification of Products of the Uridinediphospho-
N
-acetyl-
d
-Glucosamine Oxidoreductase System from
Citrobacter freundii
ATCC 10053
Authors: Daniel Amiram , Raff Rudolf A. , Wheat Robert W.
Published: January 2020

Uridinediphospho-
N
-acetyl glucosamine is converted to one or more uridine-diphospho-4-keto-6-deoxy-2-acetamidohexose derivatives by an enzyme from
Citrobacter freundii
ATCC 10053. Borohydride reduction of reaction products followed by acid hydrolysis yielded several amino sugars. Two of these were identified as fucosamine and quinovosamine by chromatography and ninhydrin degradation.
Biochemical Studies on the Thermal Dimorphism of
Paracoccidioides brasiliensis
Authors: Kanetsuna Fuminori , Carbonell Luis M. , Azuma Ichiro , Yamamura Yuichi
Published: January 2020

The biochemical and morphological changes of the yeastlike (Y) form to the mycelial (M) form of
Paracoccidioides brasiliensis
were examined. The main polysaccharide of hexoses of the Y-form cell wall was α-glucan, whereas the polysaccharides of the M-form cell wall were β-glucan and galactomannan. The α-glucan of the Y form contained mainly α-(1 → 3)-glycosidic linkage. The β-glucan of the M form contained mainly β-(1 → 3)-glycosidic linkage with a few branches at C-6 position. The incorporation of
14
C-glucose into the cell wall glucans showed that synthesis of α-glucan decreased rapidly after the temperature of the culture was changed from 37 to 20 C. The synthesis of β-glucan was augmented at an early stage of the morphological change. The M-form cell wall contained 12 times more disulfide linkage than the Y form. The cell-free extracts of the whole cell of the Y form had five times more protein disulfide reductase activity than the M form, whereas extracts of the M form contained five to eight times more β-glucanase activity than the Y form. From these results, a hypothesis for the production of the M form from the Y form is proposed.
Structure and Chemical Composition of Prospheroplast Envelopes ofSaccharomyces cerevisiaeandHansenula anomala
Authors: Darling Sven , Theilade Jørgen , Birch-Andersen Aksel
Published: January 2020

Cells ofSaccharomyces cerevisiaeandHansenula anomalawere digested with snail enzyme under conditions yielding prospheroplasts. Surrounding envelopes were isolated after lysis of prospheroplasts in distilled water. The envelope material was embedded and sectioned for electron microscopy, and thin, hollow structures still retaining the elongated form of the original cells were seen. The envelopes were of low electron density in sections stained with uranyl magnesium acetate and lead citrate, but were more electron-dense when stained with phosphotungstic acid. Shadowed preparations of prospheroplast envelopes revealed structures resembling ghosts. These “ghosts” were similar to the original cells in form and size but seemed to be very thin. Varying numbers of anular structures (bud scars) were found on them. Chemical analyses of the envelope indicated that an alkali-soluble glucan was a major constituent. The results show that the prospheroplast envelope is part of the original cell wall of the yeast and is located in close apposition to the cytoplasmic membrane.
Photoreactivation, Excision, and Strand-Rejoining Repair in R Factor-Containing Minicells of
Escherchia coli
K-12
Authors: Paterson M. C. , Roozen K. J.
Published: January 2020

Chromosomeless “minicells” are formed by misplaced cell fissions near the polar extremities of an
Escherichia coli
K-12 mutant strain. Resistance (R)-factor deoxyribonucleic acid (DNA) can be introduced into minicells by segregation from an R
+
(R64-11) derivative of the original mutant. We have assessed the ability of R
+
minicells to correct defects produced in their plasmid DNA by ultraviolet (UV) and gamma radiations. Minicells harboring plasmid DNA, in comparison with their repair-proficient minicell-producing parents, possess (i) an equal competence to rejoin single-strand breaks induced in DNA by gamma rays, (ii) a reduced capacity for the photoenzymatic repair of UV-induced pyrimidine dimers, and (iii) a total inability to excise dimers, apparently owing to a deficiency in UV-specific endonuclease activity responsible for mediating the initial incision step in excision repair. Assuming that the DNA repair properties of R
+
minicells reflect the concentration of repair enzymes located in the plasmid-containing polar caps of entire cells, these findings suggest that: (i) the enzymes responsible for rejoining single-strand breaks are distributed throughout the cell; (ii) photoreactivating enzyme molecules tend to be concentrated near bacterial DNA and to a lesser extent near plasmid DNA; and (iii) UV-specific endonuclease molecules are primarily confined to the central region of the
E. coli
cell and, thus, seldom segregate with R-factor DNA into minicells.
Specific Inhibition of Cell Division by Colicin E
2
Without Degradation of Deoxyribonucleic Acid in a New Colicin Sensitivity Mutant of
Escherichia coli
Authors: Beppu Teruhiko , Kawabata Kazuo , Arima Kei
Published: January 2020

A new class of colicin sensitivity mutants of
Escherichia coli
was isolated whose cell division was specifically inhibited by colicin E
2
without detectable degradation of deoxyribonucleic acid (DNA) at 30 C. The mutant could not form colonies in the presence of colicin E
2
but recovered colony-forming ability by trypsin treatment even after prolonged incubation with the colicin. Addition of colicin E
2
to the exponentially growing mutant inhibited cell division completely but did not induce degradation of DNA into cold acid-soluble materials nor any breakage of DNA strands. Synthesis of DNA in the mutant was not inhibited, and long filamentous cells with multiple nuclear bodies were formed by the action of colicin E
2
. Degradation of ribosomal ribonucleic acid and development of prophage λ, both of which were induced by colicin E
2
in the sensitive cells, did not occur in the mutant. At the elevated temperature, however, the mutant was found to undergo colicin-induced degradation of DNA. No differences in ultraviolet light nor drug sensitivities were observed in the mutant compared to the parent
E. coli
. The data suggested that colicin E
2
had a specific inhibitory effect on cell division of
E. coli
that was not a consequence of DNA degradation.
Effect of Unsaturated Fatty Acids on the Development of Respiration and on Protein Synthesis in an Unsaturated Fatty Acid Mutant of
Saccharomyces cerevisiae
Authors: Gordon P. A. , Lowdon M. J. , Stewart P. R.
Published: January 2020

The extent of development of respiratory function induced by aeration of an anaerobically grown unsaturated fatty acid auxotroph of
Saccharomyces cerevisiae
is determined by the availability, endogenous or externally supplied, of unsaturated fatty acid. The synthesis of mitochondrial and cytoplasmic enzymes during aeration appears to have a similar basis of regulation by available unsaturated fatty acid. Levels of unsaturated fatty acid that permit the synthesis of mitochondrial enzymes also result in a substantial stimulation of cellular protein synthesis.
Properties of an R Factor Which Originated in
Pseudomonas aeruginosa
1822
Authors: Grinsted John , Saunders J. R. , Ingram Lewis C. , Sykes R. B. , Richmond M. H.
Published: January 2020

RP1, a group of genes specifying resistance to carbenicillin, neomycin, kanamycin, and tetracycline and originating in a strain of
Pseudomonas aeruginosa
, was freely transmissible between strains of
P. aeruginosa, Escherichia coli
, and
Proteus mirabilis
. Acquisition of the multiple drug resistance specified by RP1 by these strains was accompanied by acquisition of an extrachromosomal satellite of covalently closed circular deoxyribonucleic acid of molecular weight about 40 million daltons and of buoyant density 1.719 g/cm
3
(60% guanine plus cytosine).
Turnover of Putrescine in a
Pseudomonas
Species
Authors: Michaels Ruth , Tchen T. T.
Published: January 2020

A
Pseudomonas
species was found to readily take up labeled putrescine added in trace amounts to any of four growth media, bis-(3-aminopropyl)-amine, 4-aminobutyrate, glucose-NH
3
, and Casamino Acids, although the rate of uptake varied considerably from one medium to another. Putrescine degradation, as well as excretion and conversion to hydroxyputrescine, was demonstrated in all four media, indicating that this organism has a constitutive putrescine degradation pathway. The extents of putrescine degradation, excretion, and conversion to hydroxyputrescine are shown for these four growth media through an incubation period of 1 hr. These results document more fully the experimental details behind a previous communication which postulated that the constitutive degradation of putrescine participates in the regulation of intracellular putrescine concentration. The significance of this apparent violation of the general concept that synthetic end products are normally not degraded is discussed.
Interaction of L Cells andChlamydia psittaci: Entry of the Parasite and Host Responses to Its Development
Authors: Friis Robert R.
Published: January 2020

The entry and development ofChlamydia psittaciin the L cell was studied by using purified, infectious parasites at high multiplicity. Entry of the parasite was accomplished by an act of phagocytosis by the host which was independent of an adsorption stage but was temperature-dependent. Kinetic studies of phagocytosis performed with14C-amino acid-labeled, purified parasites indicated that the rate of phagocytosis was directly proportional to the multiplicity of inoculation. Electron microscopy of cells infected at high multiplicity with purified infectiousC. psittacishowed that phagocytosed chlamydiae were segregated in a host phagocytic vacuole throughout their developmental cycle which consisted of the transition of infecting elementary bodies to reticulate bodies dividing by binary fission, followed by the reemergence of a population of elementary bodies. The process of the transition was examined and a proposed sequence of intermediate bodies is presented. In isopycnic gradients of fractionated, infected L cells, chlamydial phagocytic vacuoles were apparent as a dense band distinct from lysosome and mitochondrion peaks, as indicated by acid phosphatase and cytochrome oxidase activities. Chlamydiae inactivated by heat or neutralized by antiserum were phagocytosed and appeared in lysosomes within 12 hr after infection according to electron microscopy; however, chlamydiae which were continuously inhibited in their development by chloramphenicol were retained intact in the cell for 24 hr without lysosomal response. The possibility of a lysosomal inhibitor on the native parasite is discussed.
Electron-Dense Particles Resembling Ribosomes in Mesosomes of
Bacillus subtilis
Authors: Matheson A. , Kwong M. C. M.
Published: January 2020

Thin-sectioning of
Bacillus subtilis
ATCC 6633 protoplasts and cells has revealed electron-dense particles resembling cytoplasmic ribosomes in mesosomal tubules and vesicles.
Isoleucine Accumulation by Regulatory Mutants of
Serratia marcescens
: Lack of Both Feedback Inhibition and Repression
Authors: Kisumi Masahiko , Komatsubara Saburo , Sugiura Masaki , Chibata Ichiro
Published: January 2020

Double mutants of
Serratia marcescens
resistant to isoleucine hydroxamate and α-aminobutyric acid accumulated large amounts of isoleucine in a salts-sugar medium and lacked both feedback inhibition and repression of the isoleucine biosynthesis.
Identification of Named Cultures of
Bacillus calidolactis
as
Bacillus stearothermophilus
Authors: Fields M. L. , Harris O.
Published: January 2020

A study was made of 23 cultures of
Bacillus calidolactis
. By using cultural, biochemical, and per cent guanine plus cytosine methods, the cultures were found to be
B. stearothermophilus
.
Regulation of Exocellular Proteases in
Neurospora crassa
: Induction and Repression of Enzyme Synthesis
Authors: Drucker H.
Published: January 2020

Neurospora crassa
strain 74A grown on Vogel's medium containing bovine serum albumin (BSA) as principal carbon source secretes proteolytic enzymes which appear in the culture filtrate. Low concentrations of sucrose (0.1%) are necessary for growth from conidia, as conidia will not germinate on BSA alone. Once growth is initiated, however, protease production begins and at 5 to 6 hr growth and enzyme production are parallel. Higher concentrations of sucrose (0.5-2%) repress protease synthesis. Other metabolizable materials (sugars, amino acids, peptide mixtures) also repress protease synthesis. Some sugars will not sustain growth but allow germination and full induction of protease in the presence of protein. A material found in culture fluids of cells during induction of protease synthesis when added to repressed cultures causes a five-fold increase in the amount of protease production, although this is still approximately half that of normally induced cells. This material appears to be produced by induced cells in as little as 2 hr of culture, which is before detectable levels of protease can be found. It is heat-stable, of low molecular weight, and is not a simple product of protein digestion by the
N. crassa
proteases.
Regulation of Valine Catabolism in
Pseudomonas putida
Authors: Marshall Vincent dePaul , Sokatch John R.
Published: January 2020

The activities of six enzymes which take part in the oxidation of valine by
Pseudomonas putida
were measured under various conditions of growth. The formation of four of the six enzymes was induced by growth on
d
- or
l
-valine:
d
-amino acid dehydrogenase, branched-chain keto acid dehydrogenase, 3-hydroxyisobutyrate dehydrogenase, and methylmalonate semialdehyde dehydrogenase. Branched-chain amino acid transaminase and isobutyryl-CoA dehydrogenase were synthesized constitutively.
d
-Amino acid dehydrogenase and branched-chain keto acid dehydrogenase were induced during growth on valine, leucine, and isoleucine, and these enzymes were assumed to be common to the metabolism of all three branched-chain amino acids. The segment of the pathway required for oxidation of isobutyrate was induced by growth on isobutyrate or 3-hydroxyisobutyrate without formation of the preceding enzymes.
d
-Amino acid dehydrogenase was induced by growth on
l
-alanine without formation of other enzymes required for the catabolism of valine.
d
-Valine was a more effective inducer of
d
-amino acid dehydrogenase than was
l
-valine. Therefore, the valine catabolic pathway was induced in three separate segments: (i)
d
-amino acid dehydrogenase, (ii) branched-chain keto acid dehydrogenase, and (iii) 3-hydroxyisobutyrate dehydrogenase plus methylmalonate semialdehyde dehydrogenase. In a study of the kinetics of formation of the inducible enzymes, it was found that 3-hydroxyisobutyrate and methylmalonate semialdehyde dehydrogenases were coordinately induced. Induction of enzymes of the valine catabolic pathway was studied in a mutant that had lost the ability to grow on all three branched-chain amino acids. Strain PpM2106 had lowered levels of branched-chain amino acid transaminase and completely lacked branched-chain keto acid dehydrogenase when grown in medium which contained valine. Addition of 2-ketoisovalerate, 2-ketoisocaproate, or 2-keto-3-methylvalerate to the growth medium of strain PpM2106 resulted in induction of normal levels of branched-chain keto acid dehydrogenase; therefore, the branched-chain keto acids were the actual inducers of branched-chain keto acid dehydrogenase.
New Amino Acid Regulatory Locus Having Unusual Properties in Heterozygous Merodiploids
Authors: Kline Ellis L.
Published: January 2020

Spontaneous mutants of
Escherichia coli
B/r resistant to 5′,5′,5′,-trifluoro-
dl
-leucine contain defects in a gene which maps to the left of the threonine region. Low-level constitutive expression of the isoleucine-valine and leucine operons is caused by this mutation in haploid strains. This is in contrast to extremely high levels of gene expression in the heterozygous merodiploids (F' wild type/mutant allele). The properties of these mutants define a new locus and suggest that it encodes a subunit protein which is involved in the repression of the structural genes for the branched-chain amino acid pathways.
Predator-Prey Interactions ofDictyostelium discoideumandEscherichia coliin Continuous Culture
Authors: Tsuchiya H. M. , Drake J. F. , Jost J. L. , Fredrickson A. G.
Published: January 2020

Dictyostelium discoideumandEscherichia coliwere aerobically propagated in mixed continuous culture in a predator-prey relationship, and the effects of temperature and holding times were examined. Oscillations developed in the concentration of glucose, the limiting substrate forE. coli, and in the densities of the two populations, but eventually steady-state populations were reached. The experimental data were analyzed according to the Lotka-Volterra model for prey-predator relationships and by the Monod model for saturation kinetics. A comparison of the adequacy of the two models in describing predation is given.
Osmolar Concentration and Fixation of Mycoplasmas
Authors: Lemcke Ruth M.
Published: January 2020

Broth cultures of
Acholeplasma laidlawii
were fixed with various concentrations of cacodylate-buffered glutaraldehyde. The shape and ultrastructure of the organisms varied with the osmolar concentration of the fixative. When the fixation mixture was hypertonic to the culture medium, ultrathin sections suggested that the cells had shrunk. Phosphate buffer, sodium chloride, or sucrose at comparable osmolaities had the same effect as sodium cacodylate. Glutaraldehyde itself also contributed to the osmotic effects of the fixation mixture but to a lesser extent than salts or sucrose, to which the cell membrane is impermeable. The osmolar concentration of the fixation mixture seemed of greater importance than
p
H in determining morphology. The mycoplasma was still susceptible to damage by high concentrations of cacodylate after fixation with 2.5% glutaraldehyde. The best procedure was to fix and wash the organism under conditions isotonic with the growth medium. These conditions were also satisfactory for a filamentous mycoplasma,
Mycoplasma orale
.
New Type of Ultraviolet Light-Sensitive Mutation in Yeast
Authors: Parry Elizabeth M. , Parry James M.
Published: January 2020

Four temperature-sensitive ultraviolet light-sensitive mutants of yeast have been isolated. All four mutations show complementation in diploid cells and the phenotypes associated with the
rad
(
ts
) mutations are the result of the activities of single mendelian genes.
Biosynthesis of Riboflavine in
Saccharomyces cerevisiae
: the Role of Genes
rib
1
and
rib
7
Authors: Oltmanns O. , Bacher A.
Published: January 2020

Haploid strains of
Saccharomyces cerevisiae
with mutations in two different
rib
genes were constructed. These strains were studied by tetrad analysis and by quantitative determination of accumulation products. The genes
rib
1
,
rib
7
, and
rib
2
are not linked to each other.
rib
1
-
rib
7
strains and
rib
1
-
rib
2
strains exhibit the phenotypic properties of
rib
1
strains.
rib
7
-
rib
2
strains show the phenotypic properties of
rib
7
strains. The results support the conclusion that the genes
rib
1
and
rib
7
code for the first and second enzyme of the riboflavine pathway, respectively.
Protection of Normal, Lysogenic, and Pyocinogenic Strains Against Ultraviolet Radiation by Bound Acriflavine
Authors: Alper Tikvah , Forage A. J. , Hodgkins Brenda
Published: January 2020

The presence of bound acriflavine protects bacteria against the lethal effects of ultraviolet (UV) light, presumably because pyrimidine dimer formation is inhibited. Although acriflavine present in plating medium usually results in reduced viable counts from irradiated bacteria, no enhancement of lethal effects is observed when acriflavine is added to irradiated bacteria left in suspending buffer for 45 min before plating. Acriflavine remaining bound to the deoxyribonucleic acid of irradiated bacteria at the time they are plated likewise does not affect their survival. Protection is precisely dose-modifying unless some killing of bacteria by UV results from induction of prophage, against which bound acriflavine is less protective, or from induction of pyocin, against which there is no protection at all. It is inferred that prophage induction proceeds in part, and pyocin induction wholly, by virtue of effects of UV other than pyrimidine dimerization. The response of
Escherichia coli
strain B to radiation has been postulated to be attributable in part to induction of a prophage or a lethal protein; but exact dose modification was observed for this strain, to about the same extent, whether or not the irradiated organisms were grown in conditions thought to enhance the expected contribution to killing if such a mechanism were involved. Our results support the hypothesis that the inhibition by acriflavine of dimer formation is attributable to energy transfer mechanisms. They fail to support the hypothesis that shapes of survival curves (in particular the manifestation of “shoulders”) can be attributed to inactivation by radiation of repair enzymes.
Genetic Analysis of Transfer by the
Escherichia coli
Sex Factor F, Using P1 Transductional Complementation
Authors: Willetts Neil , Achtman Mark
Published: January 2020

P1 transduction has been used to perform a complementation analysis of a series of transfer-deficient mutants of F
lac
. The results define ten cistrons and are consistent with the results of a conjugational analysis presented in an accompanying report. Both sets of results are summarized here. Between them, they define eleven cistrons,
traA
through
traK
, necessary for conjugational deoxyribonucleic acid (DNA) transfer. Mutants in
traI
and
traD
and some in
traG
still make F-pili, although
traD
mutants are resistant to f2 phage; their products may be involved in conjugational DNA metabolism. Other mutants in
traG
and all mutants in the remaining eight cistrons do not make F-pili. One of these,
traJ
, may be a control cistron, and the others may specify a biosynthetic pathway responsible for synthesis and modification of the F-pilin subunit protein and its assembly into the F-pilus.
N
-Acetylmuramyl-
l
-Alanine Amidase of
Bacillus licheniformis
and Its
l
-Form
Authors: Forsberg C. W. , Ward J. B.
Published: January 2020

A cell wall lytic enzyme has been demonstrated to be a component of the membrane of
Bacillus licheniformis
NCTC 6346 and an
l
-form derived from it. The lytic enzyme, characterized as an
N
-acetylmuramyl-
l
-alanine amidase, is solubilized from membranes by nonionic detergents. Ionic detergents inactivate the enzyme. In the bacterium the specific activities of amidase and
d
-alanine carboxypeptidase in mesosomes are approximately 65% of those in membranes. Selective transfer of lytic enzyme from nongrowing L-forms, L-form membranes, and protoplasts to added walls occurred after mixing, and 31 to 77% of the enzyme lost from L-form membranes was recovered on the walls. Membranes isolated from L-forms growing in the presence of added walls contained as little as 13% of the amidase found in membranes of a control culture. These results have been interpreted as showing that in vivo the amidase is “bound” to the surface of the bacterial cell membrane in such a location that it can be readily accessible to the cell wall.
Effect of the Folic Acid Analogue, Trimethoprim, on Growth, Macromolecular Synthesis, and Incorporation of Exogenous Thymine inEscherichia coli
Authors: Dale Beverly A. , Greenberg G. Robert
Published: January 2020

The effect of trimethoprim [2,4-diamino-5(2′,4′,5′trimethoxybenzyl)-pyrimidine] in the presence of thymine onEscherichia coliB temperature-sensitive and non-temperature-sensitive Thy′strains and a phosphodeoxyribomutase-negative mutant was studied. The inhibitory effect of 5 μg of trimethoprim per ml on the growth ofE. coliB was not overcome by thymine, thymidine, or thymidylate even in the presence of one-carbon metabolites and related metabolites. Deoxyribonucleic acid (DNA) and protein synthesis were more severely inhibited than ribonucleic acid (RNA) synthesis. The inhibition of DNA synthesis was partially reversed by addition of deoxyadenosine to increase the incorporation of exogenous thymine. By contrast, the inhibition of protein was not reversed even with one-carbon metabolites present, in keeping with the requirement for formylmethionyl-transfer RNAFfor initiation. However, the inhibition of both DNA and protein synthesis in a phosphodeoxyribomutase-negative strain by 1 μg of trimethoprim per ml with thymine present was partially reversed by deoxyadenosine and one-carbon metabolites, and nearly normal growth occurred. 5-Fluorodeoxyuridine added at the time of addition of trimethoprim prevented the inhibition. Sulfadiazine in the presence of thymine inhibited both Thy+and Thy−strains whereas trimethoprim (with thymine) did not inhibit Thy−organisms. The effect of trimethoprim on the incorporation of labeled thymine into DNA was also studied. These experiments support the concept that trimethoprim in conjunction with the action of thymidylate synthetase inhibits the growth of Thy+cells because of a depletion of tetrahydrofolate. DNA synthesis is inhibited initially by a limitation of thymine nucleotide precursor, resulting from the indirect inhibition of thymidylate synthetase and the poor incorporation of exogenous thymine.