bluuebunny/crossref_metadata_2025 huggingface dataset:
Hormonal Interactions in
Mucor mucedo
and
Blakeslea trispora
Authors: Van Den Ende H. , Wiechmann A. H. C. A. , Reyngoud D. J. , Hendriks T.
Published: January 2020

Evidence is presented that progametangia in both the
plus
and the
minus
mating types of
Mucor mucedo
can be induced by
one
substance, namely (−)-trisporic acid B. A method is described for the determination of the concentration of the sex factors (trisporone, trisporic acid B, trisporic acid C) in mated cultures of
Mucorales
by polarography. It can be demonstrated that the amount of
plus
mycelium is limiting for the production of the sex factors in
Blakeslea trispora
. It is shown that the
minus
type of this organism is able to synthesize the sex factors when incubated in the filtered medium of a mated culture. Cycloheximide and 5-fluorouracil inhibit strongly the sex factor production in a mated culture of
B. trispora
at any time. This result suggests that sexual activity comprises the synthesis of proteins which are involved in the production of the sex factors.
ICR-Induced Frameshift Mutations in the Histidine Operon of
Salmonella
Authors: Oeschger Nicole S. , Hartman Philip E.
Published: January 2020

Both the acridine half-mustard, ICR191, and the nonalkylating azaacridine derivative, ICR364-OH, induce three classes of frameshift mutations in the histidine operon of
Salmonella typhimurium
. (i) One class is completely stable in reversion tests and is presumed to represent deletion of one or a few critical nucleotide pairs or two nearby frameshifts. One extended deletion was found out of 11 stable mutations. (ii) Of two spontaneously reverting classes which also are considered to predominantly involve base deletions, one is unaffected in reversion with ICR191, nitrosoguanidine, and diethylsulfate, and the other is induced to revert with ICR191. (iii) A third class, considered to predominantly involve base additions, responds in reversion tests with ICR191 as well as with nitrosoguanidine and diethylsulfate. Other investigators have shown that one mutant of this class is a “plus” frameshift and that nitrosoguanidine acts in reversion to delete a guanine plus cytosine base pair. Although such plus frameshifts are found with high frequency among mutations selected from acridine-treated bacteria or when strong selection pressure is applied for their detection in reversion tests, data from this laboratory indicate that this class of plus frameshifts is rare among mutations derived spontaneously or after treatment with a variety of other mutagens. Finally, we demonstrate that the alkylating ICR191 and the nonalkylating ICR364-OH preferentially cause mutations in different chromosome regions and that their spectra of activity only partially overlap that found for spontaneous frameshift mutations.
Ultrastructural Changes During the Yeastlike to Mycelial-Phase Conversion ofBlastomyces dermatitidisandHistoplasma capsulatum
Authors: Garrison Robert G. , Lane James W. , Field Marvin F.
Published: January 2020

Fine details of the sequential anatomical events occurring during yeast to mold morphogenesis of the dimorphic fungal pathogensBlastomyces dermatitidisandHistoplasma capsulatumas seen in ultrathin sections are described and illustrated by electron micrographs. Discrete intracytoplasmic membrane systems intimately associated with the plasma membrane were observed to be formed within 6 to 8 hr after induction of the conversion process. Within 12 to 18 hr, an intermediate or transitional cell with Woronin bodies at the septum was formed from the converting yeastlike cell. Both cells were noted to contain increased numbers of mitochondria. At approximately 48 hr from the initial induction of the conversion stimuli, the newly forming hyphal cells were observed to produce postconversional intracytoplasmic membrane systems seen normally in the ultrastructural organization of the fully established mycelial-phase cell. These membrane systems appear to be associated with normal septal formation. Although minor variations of time were observed in the occurrence of the sequential events, it is suggested that yeastlike to mycelial-phase conversion of these two fungal pathogens proceeds via a similar mechanism of ultrastructural reorganization.
Model for Cell Wall Growth of
Streptococcus faecalis
Authors: Higgins Michael L. , Shockman Gerald D.
Published: January 2020

In exponentially growing and dividing cells of
Streptococcus faecalis
, it is proposed that the leading edge of the annularly closing cross wall is the point of extension for both cross wall and peripheral wall. Peripheral wall extension is thought to be produced by the separation or splitting of the cross wall at its junction with peripheral wall. This results in the pushing of the equatorial wall bands, found on
S. faecalis
walls, to subsequatorial positions. These bands therefore mark the separation of old wall from new wall. Mesosomal formation was observed usually to precede cross wall initiation.
Isolation and Properties of a Temperature-Sensitive Sporulation Mutant of
Bacillus subtilis
Authors: Szulmajster J. , Bonamy Celine , Laporte J.
Published: January 2020

A thermosensitive sporulation mutant (t
s
-4) of
Bacillus subtilis
was isolated, and its morphological, physiological, and enzymatic properties were investigated. This mutant is able to grow equally well at 30 and 42 C, but is unable to sporulate at the higher temperature. Electron microscope studies have shown that the t
s
-4 mutant is blocked at stage zero of spore development. This was further confirmed by its inability to produce antibiotic when grown at the restrictive temperature and by the relatively low ribonucleic acid (RNA) and protein turnover during the stationary growth phase, characteristic for stage zero asporogenic mutants. At the permissive temperature, however, antibiotic production and RNA and protein turnover took place at the rate normally found in sporogenic strains of
B. subtilis
. The above properties were not altered in the parent strain when grown at either 30 or 42 C. By shifting cultures of the t
s
-4 mutant from 30 to 42 C and from 42 to 30 C at different stages of growth, we have been further able to show that the event affected at the high temperature takes place at a very early stage of spore development. As a consequence of this early block in the sporulation process, the t
s
-4 mutant grown at 42 C became defective in the late spore-specific enzymes involved in the biosynthesis of dipicolinic acid. This study suggests that the sporulation process is mediated by a regulatory protein which is altered in the thermosensitive mutant when grown at the restrictive temperature. As a result of this alteration, a pleiotropic phenotype is produced which has lost the ability to catalyze the late biochemical reactions required for spore formation.
Photodynamic Action on Native and Denatured Transforming Deoxyribonucleic Acid from
Haemophilus influenzae
Authors: León Manuel Ponce-De , Cabrera-Juárez Emiliano
Published: January 2020

The photodynamic inactivation of native or denatured transforming deoxyribonucleic acid (DNA) from
Haemophilus influenzae
is described. The inactivation at the same
p
H was higher for denatured than native DNA. At acidic
p
H, the inactivation both for native and denatured DNA was faster than at alkaline
p
H. The guanine content of photoinactivated native DNA at neutral
p
H was less than untreated DNA. The inactivation of biological activity was more extensive than the alteration of guanine. The absorption spectrum of photoinactivated native or denatured DNA was only slightly different than the control DNA at the different experimental conditions.
Isolation of Conditionally Putrescine-Deficient Mutants ofEscherichia coli
Authors: Morris David R. , Jorstad Caroline M.
Published: January 2020

Mutants defective in the conversion of arginine to putrescine were found by screening clones from mutagenized cultures for inability to produce urea during growth in arginine-supplemented media. Two partially blocked mutants were isolated; one was deficient in arginine decarboxylase and the other was deficient in agmatine ureohydrolase. As predicted from the pattern of putrescine synthesis inEscherichia coli, these mutants were conditionally putrescine-deficient. When grown in either minimal or ornithine-supplemented media, conditions which lead to preferential utilization of the ornithine to putrescine pathway, the mutants had normal intracellular polyamine levels. However, when the mutants were placed in arginine-supplemented media, the level of intracellular putrescine was lowered markedly. Under conditions where intracellular putrescine was 1% of normal, the doubling time of the mutants was increased approximately 10%. The putrescine-deficient mutants had wild-type morphology, normal levels of protein and ribonucleic acid (RNA), and stringent amino acid control of RNA synthesis.
d
-Apiose Reductase from
Aerobacter aerogenes
Authors: Neal Donna L. , Kindel Paul K.
Published: January 2020

A strain of
Aerobacter aerogenes
PRL-R3 has been isolated which utilizes
d
-apiose as its sole source of carbon. A new enzyme,
d
-apiose reductase, was discovered in this strain. The enzyme was not present when the strain was grown on
d
-glucose.
d
-Apiose reductase catalyzes the nicotinamide adenine dinucleotide-dependent interconversion of
d
-apiose and
d
-apiitol. The enzyme is specific for
d
-apiose and
d
-apiitol, with a few possible exceptions. The
K
m
for
d
-apiose is 0.02
m
. The
K
m
for
d
-apiitol is 0.01
m
. The enzyme is almost completely specific for the reduced and oxidized forms of nicotinamide adenine dinucleotide. When cell-free extracts were centrifuged at 100,000 ×
g
for 1 hr, the enzyme remained in solution. Optimal activity for the reduction of
d
-apiose was obtained at
p
H 7.5 in glycylglycine buffer, whereas for the oxidation of
d
-apiitol it was obtained at
p
H 10.5 in glycine buffer. Enzymatic reduction of
d
-apiose was not appreciably affected by the presence of 0.02
m
ethylenediaminetetraacetate. Paper chromatography and specific spray reagents were used to identify
d
-apiitol and
d
-apiose as the products of this reversible reaction.
d
-Apiose and
d
-apiitol did not serve as substrates for ribitol dehydrogenase and
d
-arabitol dehydrogenase from
A. aerogenes
PRL-R3.
Control of Uridine Diphosphate-Glucose Dehydrogenase Synthesis and Uridine Diphosphate-Glucuronic Acid Accumulation by a Regulator Gene Mutation in
Escherichia coli
K-12
Authors: Lieberman Michael M. , Shaparis Anna , Markovitz Alvin
Published: January 2020

Uridine diphosphate (UDP)-glucose dehydrogenase, the enzyme that converts UDP-glucose to UDP-glucuronic acid, was derepressed in a mucoid (
capR9
) strain of
Escherichia coli
K-12 and repressed in a nonmucoid (
capR
+
) strain. A nonmucoid mutant (strain MC 152;
capR9 non-2
) derived from the mucoid strain accumulated large quantities of nucleotides. Among these nucleotides, UDP-glucuronic acid was identified as well as guanosine triphosphate and an adenosine diphosphate-sugar. UDP-glucose dehydrogenase was still derepressed in strain MC 152. When the nonmucoid mutant was transduced to the wild-type state for this regulator gene (
capR
+
), the transductant was found to accumulate less total nucleotides, and the accumulation of UDP-glucuronic acid was abolished. UDP-glucose dehydrogenase was repressed in the
capR
+
non-2
strain but not to the same extent that it was in the
capR
+
strain.
Thymineless Death in
Escherichia coli
: Deoxyribonucleic Acid Replication and the Immune State
Authors: Cummings Donald J. , Kusy Alvin R.
Published: January 2020

Thymineless death (TLD) and nalidixic acid (NA) inactivation were studied in multiple auxotrophic strains of
Escherichia coli
B and B/r. As expected, it was found that both
E. coli
B and B/r exhibited an “immune state,” i.e., a fraction of the population survived inactivation to both TLD and NA. With glucose as a carbon source in minimal medium, 0.1 to 0.3% of strain B and 0.2 to 0.5% of strain B/r survived inactivation; with acetate as the carbon source, the surviving fractions were increased to 1 to 2% and 5 to 7%, respectively. These immune fractions could be increased in magnitude by preincubation in minimal media containing thymine. Systematic analysis of the particular supplements necessary for the immune state indicated that the absence of the required amino acids was essential for the maximal expression of immunity. However, immunity was not abolished in acetate medium even in the presence of the required supplements. Further studies on the replication of deoxyribonucleic acid (DNA) during preincubation indicated that the degree of immunity did not necessarily correlate with the completion of a round of DNA replication. This finding was supported by examining the immune state in synchronous populations. In both glucose and acetate medium, there was no significant change in the degree of immunity to inactivation within the cell cycles of
E. coli
B and B/r. We concluded that some other event, possibly inhibition of protein synthesis, was necessary in determining the degree of the immune state. DNA replication was investigated after TLD and NA inactivation, and, as expected, it was found that both events led to premature initiation of replication. The only differences observed in the effects of these two processes on DNA synthesis were the following. (i) NA-induced replication was less sensitive to chloramphenicol than was TLD. (ii) TLD-induced replication was unaffected by pretreatment of the cells with mitomycin C, but this pretreatment prevented the replication of DNA after NA treatment. It was suggested that the mechanism of action of NA could involve a monofunctional attack on the DNA.
Pyrimidine Pools and Macromolecular Composition of Pyrimidine-LimitedEscherichia coli
Authors: Dennis Patrick P. , Herman Robert K.
Published: January 2020

The growth rate of a pyrimidine-requiring strain was controlled by limiting the concentration of exogenous orotic acid. As the steady state, pyrimidine-limited growth rate was decreased, the intracellular pyrimidine pools and the total nucleic acid per unit mass of culture also decreased. The ratio of deoxyribonucleic acid to protein remained constant, whereas the ratio of ribonucleic acid to protein decreased 30% over a threefold variation in growth rate (50- to 150-min doubling times). The intracellular uridine triphosphate and cytosine triphosphate pools also decreased (although not coordinately), and the pyrimidine biosynthetic enzymes were derepressed. Cell size was unaffected by pyrimidine-mediated variation of the growth rate.
Thymineless Death in
Escherichia coli
15T
−
and Recombinants of 15T
−
and
Escherichia coli
K-12
Authors: Medoff Gerald , Overholt Sharon
Published: January 2020

Thymineless death was examined in
Escherichia coli
15T
−
and recombinants of 15T
−
and
E. coli
K-12. Those strains that were very sensitive to thymine deprivation were also very sensitive to a variety of inducing agents (mitomycin C, ultraviolet light, hydroxyurea, and nalidixic acid). Those strains that were relatively resistant to thymineless death were also relatively resistant to the inducing agents. After exposure to thymineless death and the inducing agents, sensitive strains lysed, produced colicin, and had phage particles in their lysates. These strains also showed an increase in the 6-methyladenine content of their deoxyribonucleic acid (DNA) and an increase in the DNA methylase activity of their crude extracts under these conditions. None of these effects was noted in the strains relatively resistant to thymineless death and the inducing agents. These data indicate that there are two types of thymineless death. One is represented by the strains that are very sensitive to thymine deprivation and other inducing agents and is secondary to the induction of phage ψ. The strains more resistant to thymine deprivation and the other inducing agents undergo a non-phage-mediated thymineless death. The mechanism of this latter process is currently under study.
Induction of Dimorphism in the Basidiomycete
Lenzites saepiaria
Authors: Scheld H. W. , Perry J. J.
Published: January 2020

Sugars can serve as the germinant for basidiospores of the wood-rotting fungus
Lenzites saepiaria
. Hexoses sterilized by autoclaving were better germinants than hexoses that were sterilized by filtration. The degradation products in heated hexose which were responsible for the stimulation of germination were levulinic and formic acid. Another product of hexose degradation, hydroxymethyl furfural, had a marked effect on outgrowth of
L. saepiaria
basidiospores and on the development of mycelia. Basidiospores that germinated in the presence of hydroxymethyl furfural yielded large rounded bodies that, in some cases, developed as a chain of yeastlike cells. Addition of hydroxymethyl furfural to developing mycelia resulted in the production of chains of round yeastlike structures. Similar results were obtained by treating basidiospores or mycelia with phenethyl alcohol.
Plasmid Formation After Lambda Bacteriophage Infection of
Escherichia coli-Salmonella typhosa
Hybrids
Authors: Falkow Stanley , Baron L. S.
Published: January 2020

Defective phage λ
dg
, when present in certain
Salmonella typhosa
hybrids, could be eliminated with acridine orange or ethidium bromide treatment. The λ
dg
deoxyribonucleic acid could be separated from the
S. typhosa
host deoxyribonucleic acid as a distinctly covalently closed molecule.
Induction of Filament Formation and Thymineless Death in
Escherichia coli
K-12
Authors: Gherardi M. , Sicard N.
Published: January 2020

The study of isogenic strains of
Escherichia coli
K-12 carrying mutations which control filament formation after ultraviolet irradiation showed that there is not necessarily a relationship between filament formation and thymineless death.
Ultraviolet Irradiation of the Vegetative Cells of
Dictyostelium discoideum
Authors: Freim J. O. , Deering R. A.
Published: January 2020

Experiments on the effect of ultraviolet (UV) light on the survival of vegetative
Dictyostelium discoideum
cells indicate that this is a relatively UV-resistant organism. Several factors suggest the presence of some type of repair process. Experiments to test for liquid-holding recovery and simple photoreactivation yielded negative results. Acriflavine and caffeine were utilized to possibly interfere with dark repair. Acriflavine produced no UV sensitization, but caffeine did cause a concentration-dependent decrease in survival of irradiated cells. When UV-irradiated cells were illuminated with photoreactivating light while suspended in caffeine, the survival increased above that for cells treated with caffeine alone, suggesting an overlap between lesions repaired by photorepair and dark repair. Growth experiments showed that UV light induced a dose-dependent division delay, followed by a period of retarded growth characterized by the presence of a constant fraction of nonviable cells in the irradiated population. The delayed exposure of cells to caffeine after irradiation showed that the magnitude of the caffeine sensitization diminished throughout the division-delay period. An action spectrum indicated probable nucleoprotein involvement in the induction of division delay. UV light retarded ribonucleic acid and protein synthesis and temporarily blocked deoxyribonucleic acid synthesis. However, synthesis of all three accelerated prior to the end of the division-delay period and then closely paralleled the increase in cell number.
Amino Acid Transport in
Mycobacterium smegmatis
Authors: Yabu Kunihiko
Published: January 2020

The transport of
d
-alanine,
d
-glutamic acid, and
d
-valine in
Mycobacterium smegmatis
was compared quantitatively with that of their
l
-isomers. It appeared that the uptake of
d
-alanine was mediated by an active process displaying saturation kinetics characteristic of enzyme function, whereas the uptake of
d
-glutamic acid was accomplished by a passive process showing diffusion kinetics. Both processes were involved in the uptake of
l
-alanine,
l
-glutamic acid,
d
-valine, and
l
-valine.
d
-Valine competed with
l
-valine for entry into the cell through a single active process.
d
-Alanine and
l
-alanine also utilized the same active process, but the
d
-isomer could not enter the cell through the passive process. The passive process exhibited characteristics of diffusion, but was sensitive to sulfhydryl-blocking reagents and showed competition among structurally related amino acids. These last findings suggested that the passive process is a facilitated diffusion.
Chemical and Biochemical Changes in Subcellular Fractions of Guinea Pig Liver During Infection with
Coxiella burneti
Authors: Paretsky D. , Stueckemann J.
Published: January 2020

Livers of uninfected guinea pigs and of guinea pigs infected with
Coxiella burneti
were fractionated into smooth endoplasmic reticulum, rough endoplasmic reticulum (RER), pellet, and cell sap fractions. The ribonucleic acid (RNA) and protein of each fraction were determined, and the phosphorylase, glucose-6-phosphatase, and glucosyl transferase (glycogen synthetase) activities of each fraction were measured. Decreased RNA, protein, and enzyme activities were found in the RER and pellet fractions of infected livers, with the greatest differences in the RER. The evidence indicates a solubilization of the phosphorylase and synthetase, with the enzymes moving from the RER and glycogen-containing pellet fraction to the cell sap. The data suggest the RER as a target during Q fever.
Genetic Stability of Various Resistance Factors in
Escherichia coli
and
Salmonella typhimurium
Authors: Watanabe Tsutomu , Ogata Yasuko
Published: January 2020

Genetic stability of R factors was studied in
Salmonella typhimurium
LT-2 and
Escherichia coli
K-12. It was found that
fi
+
R [or R(f)] factors were unstable in LT-2, losing their drug-resistance markers at high frequencies, and were stable in K-12;
fi
−
R [or R(i)] factors were stable in both hosts. Both
fi
+
and
fi
−
R factors were genetically stable also in recombination-deficient mutants of K-12. An
fi
+
R factor, which was unstable in
S. typhimurium
LT-2 wild type, was relatively stable in a recombination-deficient mutant of LT-2. In the spontaneous loss of the drug-resistance markers of
fi
+
R factors in LT-2, the markers for sulfanilamide, streptomycin, and chloramphenicol resistance were lost together at high frequencies and the tetracycline marker was retained stably. The remaining drug-resistance markers of the spontaneous segregants of LT-2 were transmissible to K-12 by mixed cultivation, indicating that they were still in the form of R factors.
Comparative Metabolism of Vegetative and Sporulating Cultures ofClostridium thermosaccharolyticum
Authors: Hsu Edward J. , Ordal Z. John
Published: January 2020

Cultures ofClostridium thermosaccharolyticum, under conditions of restricted growth achieved by slow feeding of glucose, showed a high degree of sporulation. Analysis of the end products showed an accumulation of ethyl alcohol in addition to butyrate and acetate, whereas, in the nonsporulating cultures, acetate and butyrate were the principal products. Incorporation of uniformly labeled14C-glucose by sporulating cells was three to four times higher than by nonsporulating cells. The efficiency of acetate assimilation into the lipid fraction of sporulating cells was at least two times higher than that of glucose. When starch was used as the carbon source, the growth rate was reduced; sporulation occurred, and the end products and carbon distribution were similar. Alcohol dehydrogenase, glucose-6-phosphate dehydrogenase, and 6-phosphogluconate dehydrogenase were preferentially formed by sporulating cells. In vegetative cells, the formation of these enzymes was repressed if the glucose concentration in the medium was increased. The change in enzyme activity appeared to be related to a morphological change in the cells and indicated an altered metabolic pattern for sporulating cells.
Mode of Action of Vibriocin
Authors: Jayawardene Asoka , Farkas-Himsley Hannah
Published: January 2020

The mechanism of action of vibriocin, a bacteriocin produced by
Vibrio comma
, was investigated. Its lethal action (as defined by the loss in colony-forming ability) was reversed by tryptic digestion within 7 to 10 min after adsorption. The bacteriocin had a pronounced inhibitory effect on deoxyribonucleic acid (DNA) synthesis, whereas ribonucleic acid (RNA) and protein synthesis continued, although at a reduced rate. Chloramphenicol protected sensitive bacteria from the lethal action. Degradation of bacterial DNA prelabeled with
3
H-thymidine, as measured by changes in acid-precipitable radioactivity, occurred 10 min after treatment with vibriocin. The bacteriocin per se had no detectable deoxyribonuclease activity. Observation of vibriocin-treated cells by phase-contrast microscopy, measurement of ultraviolet light-absorbing capacity of extracellular fluid, and
42
K-efflux studies indicated a damaged bacterial membrane. This impairment of membrane function occurred in the presence of chloramphenicol and thus, unlike the lethal effect of vibriocin, was independent of protein synthesis.
Physiological Basis of Transient Repression of Catabolic Enzymes in
Escherichia coli
Authors: Tyler Bonnie , Magasanik Boris
Published: January 2020

Transient repression of catabolic enzymes occurs in cells that encounter a new carbon compound in their growth medium, but only when the cells contain the enzyme catalyzing the transfer of phosphate from phosphoenolpyruvate to a small heat-stable protein (HPr), as well as a permease capable of transporting the new compound across the cell membrane. The newly added compound need not be metabolized. The degree and duration of the transient repression have no obvious relation to the intracellular level of the exogenously added compound. It is suggested that the actual passage of the compound through the cell membrane is responsible for the repression.
Loss of Colicinogeny inEscherichia coliStrains Infected by Certain Resistance Factors
Authors: Krčméry V. , Hurwitz C. , Fredericq P.
Published: January 2020

The original observation that in wild-type colicinogenicEscherichia colistrains the introduction of some R factors abolish their colicin production was studied in certaincol+strains bearing well-definedcolfactors. Two resistance (R) factors were used and introduced by conjugation in these strains, namely the 222 factor of Watanabe and aSalmonella typhimuriumST factor (coding for resistance to streptomycin and tetracycline only). The introduction of above mentioned R factors abolished the colicin production ofcol+strains most probably by elimination ofcolfactors. Allcolfactors, however, were not equally susceptible to elimination by the R factors tested, since colicin production in ML strains was abolished by infection by the 222 factor but not by the R factor ofS. typhimuriumST, which is able to eliminate othercolfactors.
Intracytoplasmic Membrane Structures in
Vibrio marinus
Authors: Felter R. A. , Kennedy S. F. , Colwell R. R. , Chapman G. B.
Published: January 2020

An electron microscope study of
Vibrio marinus
strains MP-1, an obligate psychrophile, and PS-207, a moderate psychrophile, revealed numerous intracellular membranous structures. The structures were found to occur more frequently in
V. marinus
strain MP-1 than in strain PS-207. The frequency of occurrence and complexity of structure were related to age of the culture. In early logarithmic phase, cells revealed invaginations of the plasma membrane. More complex membrane forms, found in late logarithmic and stationary phase, were either myelin-like sheaths, for which the term “myelemma” is proposed, or membranes randomly arranged throughout the cells. The complex membrane forms were not observed to be directly connected with the plasma membrane. However, they were often found in approximation to the plasma membrane or associated with vacuoles and circular membrane profiles. Individual membranes were of a tripartite structure and of dimensions similar to the cell wall and plasma membrane.
Ultrastructure ofMycoplasma laidlawiiDuring Culture Development
Authors: Maniloff Jack
Published: January 2020

Mycoplasma laidlawiiB has been studied by phase-contrast and electron microscopy (thin-section and negative staining). Exponential-phase cells are filaments with the following structures: surface unit membrane, nuclear material, ribosomes, and intracellular granular region. These cells appear to reproduce by binary fission. In stationary phase, the filamentous cells have numerous constrictions, giving them a beaded appearance. Nonviable death-phase cultures contain cellular debris: swollen cells, granular bodies, and other aberrant forms.
Changes in Resistance to Radiation and Heat During Sporulation and Germination of
Clostridium botulinum
33A
Authors: Durban E. , Goodnow R. , Grecz N.
Published: January 2020

During sporulation,
Clostridium botulinum
33A developed resistance to ultraviolet and gamma rays about 2 hr prior to its development of heat resistance. During germination, loss of resistance to heat, ultraviolet radiation, and gamma radiation occurred essentially simultaneously.
Gene Expression After Transformation in
Bacillus subtilis
Authors: Chasin Lawrence A. , Magasanik Boris
Published: January 2020

Sensitive assays of histidase activity were used to follow the production of this enzyme as directed by a gene newly introduced into cells of
Bacillus subtilis
by transformation. Histidase activity can be detected in histidase-negative recipient cells within 1 hr after the addition of deoxyribonucleic acid extracted from histidase-positive donors. Enzyme production continues for one to two additional hours and then ceases. Histidase production in the transformed cells is fully sensitive to catabolite repression. Catabolite repression is rapidly established after transformation of recipient cells that are resistant to this form of regulation.
Comparison of Lysyl-Transfer Ribonucleic Acid Species from Vegetative Cells and Spores of
Bacillus subtilis
by Methylated Albumin-Kieselguhr and Reversed-Phase Chromatography
Authors: Vold Barbara S.
Published: January 2020

Lysyl-transfer ribonucleic acid (tRNA) species from a spore-forming strain of
Bacillus subtilis
(168
trp2
−
) and an early blocked asporogenous mutant (
spoA
12) were compared on reversed-phase and methylated albumin-kieselguhr columns. Lysyl-tRNA species from spores and the asporogenous mutant in stationary phase both exhibited altered chromatographic profiles compared to that of log-phase cells. The major peak in spore lysyl-tRNA species eluted later than that characteristic of vegetative cells, whereas the major peak of the lysyl-tRNA species from the asporogenous mutant in stationary phase eluted earlier. Although the early eluting lysyl-tRNA species was observable on methylated albumin columns, the late eluting peak was not detectable by that column technique. By using a shallower gradient on an RPC-2 column, the resolution of all lysyl-tRNA species increased. Several subspecies were revealed. The chromatographic comparisons clearly show that both the spore-forming strain and the asporogenous mutant undergo relative increases in different lysyl-tRNA species when grown to late stationary phase. No new species seem to be involved but rather altered amounts of minor species existing in log-phase cells. The experiments also demonstrate the usefulness of reversed-phase columns for such comparisons.
Intercellular Effects on Development of Competence in
Bacillus subtilis
Authors: Goldsmith M. R. , Havas S. W. , Ma R.-I. , Kallenbach N. R.
Published: January 2020

The intercellular transfer of competence during growth under the conditions specified by the transformation procedure of Spizizen was investigated with
Bacillus subtilis
168. The rate of competence development as assayed uniformly in medium B was not affected by variations in the cell concentration, although the first appearance of transformants occurred earlier with high cell densities in medium A, approximately in proportion to the onset of the stationary phase in the culture. Growth in the presence of Pronase enhanced the frequency of transformation, but did not detectably alter the kinetics of competence development. The rate of competence increase in physiologically noncompetent cultures was not changed by mixing with competent cultures either in medium A or in medium B; however, an early appearance of transformants was noted in mixed cultures in which the proportion of competent to noncompetent cells prevented exponential growth of the noncompetent strain. These experiments indicate that the normal development of competence in
B. subtilis
is not mediated by a soluble or loosely bound protein factor capable of transmitting competence directly via cell contact. The onset of competence is thus a function of internal physiological changes which are induced by the overall metabolic state of the culture.
Mutants of
Escherichia coli
K-12 with an Altered Glutamyl-Transfer Ribonucleic Acid Synthetase
Authors: Murgola E. J. , Adelberg E. A.
Published: January 2020

Three streptomycin-suppressible lethal mutants of
Escherichia coli
K-12 have been shown to possess structurally altered glutamyl-transfer ribonucleic acid (tRNA) synthetases. Each mutant synthetase displays a
K
m
value for glutamate which is 10-fold higher than the parental value, and the mutations reside in two widely separate loci on the genetic map. Mixing of the mutant extracts in pairs gave no indication of in vitro complementation. All three enzymes charge the minor tRNA
glu
fraction identically, but one (EM 120) charges the major fraction at a twofold lower rate than do the other two (EM 102 and EM 111). Possible explanations for the existence of the two synthetase loci are presented.
Streptomycin-Suppressible Lethal Mutations in
Escherichia coli
Authors: Murgola E. J. , Adelberg E. A.
Published: January 2020

Forty-one mutants have been isolated which require streptomycin for growth on complete medium. These streptomycin-suppressible lethal mutations are located randomly around the
Escherichia coli
genetic map; during growth in liquid culture, they exhibit a variety of responses to the removal of streptomycin as judged by turbidity, cell morphology, and macromolecular synthesis. In particular, some mutants are primarily affected in protein or ribonucleic acid (RNA) synthesis (or both), one in deoxyribonucleic acid synthesis, and two in lipid synthesis. Ten mutants affected in protein synthesis were examined for the activities of all twenty aminoacyl-transfer RNA synthetases, and three were found to have altered glutamyl-transfer RNA synthetase activities. The advantages of this method for isolating a wide variety of conditional lethal mutants are discussed.
Carbohydrate Metabolism inSpirochaeta stenostrepta
Authors: Hespell Robert B. , Canale-Parola E.
Published: January 2020

The pathways of carbohydrate metabolism inSpirochaeta stenostrepta, a free-living, strictly anaerobic spirochete, were studied. The organism fermented glucose to ethyl alcohol, acetate, lactate, CO2, and H2. Assays of enzymatic activities in cell extracts, and determinations of radioactivity distribution in products formed from14C-labeled glucose indicated thatS. stenostreptadegraded glucose via the Embden-Meyerhof pathway. The spirochete utilized a clostridial-type clastic reaction to metabolize pyruvate to acetyl-coenzyme A, CO2, and H2, without production of formate. Acetyl-coenzyme A was converted to ethyl alcohol by nicotinamide adenine dinucleotide-dependent acetaldehyde and alcohol dehydrogenase activities. Phosphotransacetylase and acetate kinase catalyzed the formation of acetate from acetyl-coenzyme A. Hydrogenase and lactate dehydrogenase activities were detected in cell extracts. A rubredoxin was isolated from cell extracts ofS. stenostrepta. Preparations of this rubredoxin stimulated acetyl phosphate formation from pyruvate by diethylaminoethyl cellulose-treated extracts ofS. stenostrepta, an indication that rubredoxin may participate in pyruvate cleavage by this spirochete. Nutritional studies showed thatS. stenostreptafermented a variety of carbohydrates, but did not ferment amino acids or other organic acids. An unidentified growth factor present in yeast extract was required by the organism. Exogenous supplements of biotin, riboflavin, and vitamin B12were either stimulatory or required for growth.
Mapping of a Locus for Unsaturated Fatty Acid Biosynthesis in
Escherichia coli
Authors: Epstein Wolfgang , Fox C. Fred
Published: January 2020

A mutation affecting unsaturated fatty acid biosynthesis in
Escherichia coli
has been mapped. This mutation, which is in the
fabB
locus, lies between the
aroC
and
purF
loci.
Radiation Sensitivity ofHaemophilus influenzae:a Composite Response
Authors: Barnhart B. J. , Cox S. H.
Published: January 2020

The survival of ultraviolet (UV)-irradiated cultures ofHaemophilus influenzaeRd is determined by at least two responses: (i) excision-repair ability and (ii) UV-induced cell lysis. An UV-resistant mutant, BC200, has the same capabilities as the wild type, Rd, for excising dimers but does not exhibit lysis. Lytic response is dose-dependent. Relative to the wild type, a lower dose of UV causes lysis of a UV-sensitive mutant, BC100, which is incapable of excising thymine dimers. A lytic protein is present in cultures undergoing lysis. Synthesis of this protein is initiated 45 to 60 min after irradiation. Lysis appears to be due to derepression of a defective prophage which codes for an endolysin-like lytic enzyme.
Separation of Donor and Recipient Bacteria by Column Chromatography
Authors: Zsigray Robert M. , Fulk George E. , Lawton William D.
Published: January 2020

When donor and recipient strains of
Escherichia coli
were added to columns containing Cellex-P (a cation-exchange cellulose), more than 80% of the female cells passed through the column but only 11% or less of the male cells were eluted. However, when donor strains were blended before their addition to the column, the majority of these cells were eluted. These results indicated that the filamentous appendages termed F pili (which are removed by blending) were the structures responsible for the adherence of donor cells to the cellulose.
Survival, Deoxyribonucleic Acid Breakdown, and Synthesis inSalmonella typhimuriumas Compared withEscherichia coliB Strains
Authors: Hudnik-Plevnik Tamara A. , Djordjević Nadežda
Published: January 2020

Salmonella typhimuriumLT-2 was compared with radioresistant (B/r) and radiosensitive (Bs−2) strains ofEscherichia coliin respect to the survival, deoxyribonucleic acid (DNA) breakdown, and DNA synthesis after X irradiation. It is shown thatS. typhimuriumLT-2 is about four times more sensitive thanE. coliB/r but less sensitive than Bs−2. The DNA breakdown is inS. typhimuriumLT-2 lower than the postirradiation breakdown of DNA in bothE. colistrains and DNA synthesis proceeds in this bacterium in spite of a much lower survival, as in the radioresistantE. coliB/r.
Gene Controlling
l
-Glutamic Acid Decarboxylase Synthesis in
Escherichia coli
K-12
Authors: Lupo Meir , Halpern Yeheskel S.
Published: January 2020

Genetically related
Escherichia coli
K-12 strains were found to differ widely in their
l
-glutamic acid decarboxylase (GAD) activity. This variation is due to differences in the amount of GAD produced by the different cultures, rather than to the appearance of altered enzymes differing in catalytic activity. A regulatory gene,
gadR
, which controls the amount of GAD was mapped on the
E. coli
K-12 chromosome. A strain with a lesion in the structural gene for GAD is described.
Effect of Adenosine and Deoxyadenosine on the Incorporation and Breakdown of Thymidine in
Escherichia coli
K-12
Authors: Yagil Ezra , Rosner Arie
Published: January 2020

Deoxyadenosine (AdR) and adenosine (AR) enhance the incorporation of thymidine (TdR) into bacterial deoxyribonucleic acid (DNA) by the inhibition of TdR phosphorolysis in vivo. Neither of the purine nucleosides has an effect on the reaction catalyzed by TdR phosphorylase in vitro. AdR induces TdR phosphorylase and both purine nucleosides induce purine nucleoside phosphorylase. AR can stimulate uptake of more TdR into bacterial DNA than AdR.
Autolysin(s) of
Bacillus subtilis
as Dechaining Enzyme
Authors: Fan David P.
Published: January 2020

Bacillus subtilis
bacteria grow exponentially as long filaments in well-aerated cultures at 48 C. These filaments are chains of cells which can become unlinked when a
B. subtilis
autolysin or egg white lysozyme is added to the culture medium.
Similarities in the Action Patterns of Exopolygalacturonate Lyase and Pectinesterase from
Clostridium multifermentans
Authors: Lee M. , Miller L. , Macmillan J. D.
Published: January 2020

Exopolygalacturonate lyase and pectinesterase from
Clostridium multifermentans
were assayed simultaneously in the same reaction mixture which contained a highly esterified pectin, polymethyl polygalacturonic acid methyl glycoside. Lyase is specific for unesterified galacturonide residues and cannot degrade this substrate in the absence of the esterase. The rate for esterase was twice the rate for lyase throughout the entire course of the combined reaction. Thus, the molar ratio of the two enzyme activities was the same since the product of the lyase is an unsaturated digalacturonic acid containing two free carboxyl groups. Since clostridial exopolygalacturonate lyase is known to degrade polygalacturonate in a linear manner beginning from the reducing ends of polygalacturonate chains, it was apparent that clostridial pectinesterase must hydrolyze methyl groups in highly esterified pectins with an action pattern similar to that of the lyase. Otherwise it would be impossible for the two enzyme rates to have corresponded on the basis of a 2:1 ratio.
Reversion to the Streptococcal State of Enterococcal Protoplasts, Spheroplasts, and L-Forms
Authors: King James R. , Gooder Harry
Published: January 2020

A method is described for predetermining whether lysozyme-damaged enterococci grow as either the parent strain or as L-forms. Organisms treated with lysozyme grew as L-forms on media solidified with low concentrations of agar, or the damaged cells grew as streptococci on media solidified with high concentrations of gelatin. After induction, some of the L-forms reverted to the parent strain, but most did not during three routine subcultures. Continued spontaneous reversion occurred through approximately 30 subcultures after induction. However, subsequent progeny did not revert, even when subjected to conditions such as the gelatin medium which strongly favors growth in the streptococcal phase.
Characterization of aStaphylococcus aureusBacteriocin
Authors: Gagliano V. J. , Hinsdill R. D.
Published: January 2020

The bacteriocin produced by a strain ofStaphylococcus aureushas been isolated and designated staphylococcin (414), and a study was made of its chemical, physical, and biological properties. The staphylococcin is released in appreciable quantities after breakage of the cells and can be purified through differential centrifugation and column chromatography. In the native state, it appears to be a lipoprotein-carbohydrate complex with a molecular weight in excess of 200,000. The complex can be dissociated by sodium dodecyl sulfate into smaller subunits which retain activity. The gross chemical and physical properties of the bacteriocin closely resemble those ascribed to certain preparations of cell membranes. Staphylococcin (414) is not a lytic enzyme like lysostaphin and does not have the same spectrum of activity. Like other bacteriocins from gram-positive microorganisms, it does not inhibit any gram-negative bacteria, but does inhibit several other genera.
Repression of Acetyl-Coenzyme A Carboxylase by Unsaturated Fatty Acids: Relationship to Coenzyme Repression
Authors: Birnbaum Jerome
Published: January 2020

It has been reported that the level ofd-biotin in the growth medium ofLactobacillus plantarumregulates the synthesis of apoacetyl-coenzyme A (CoA) carboxylase; high levels cause repression, and deficient levels effect derepression. In this study, evidence has been obtained which suggests that coenzyme repression by biotin is an indirect effect; i.e., biotin regulates the synthesis of unsaturated fatty acids which are the true repressors of the acetyl-CoA carboxylase. This was observed in an experiment in which long-chain unsaturated fatty acids were added to media containing deficient, sufficient, or excess levels ofd-biotin. In every case, independently of the biotin concentration for growth, the unsaturated fatty acids caused a severe repression of the carboxylase. Saturated fatty acids were without effect. The level of oleic acid required to give maximal repression was 50 μg/ml. The free fatty acids had no adverse effect on the activity of the cell-free extracts nor on the permeation ofd-biotin into the cell. Saturated and unsaturated fatty acids decreased the rate of holocarboxylase formation fromd-biotin and the apoacetyl-CoA carboxylase in the extracts. It is concluded that there are at least three mechanisms that control the acetyl-CoA carboxylase in this organism: (i) indirect coenzyme repression byd-biotin, (ii) repression by unsaturated fatty acids, and (iii) regulation of the activity of the holocarboxylase synthetase by both saturated and unsaturated fatty acids.
Mutations Affecting Iron Transport in
Escherichia coli
Authors: Cox G. B. , Gibson F. , Luke R. K. J. , Newton N. A. , O'Brien I. G. , Rosenberg H.
Published: January 2020

A mutant of
Escherichia coli
K-12 unable to form an essential component of the enterochelin-dependent iron transport system has been isolated. This strain carries a mutation in a gene designated
fep
, mapping close to two genes,
entA
and
entD
, concerned with enterochelin synthesis. Strain AN102, which carries the
fep
−
allele, accumulates large quantities of enterochelin and gives a growth response to sodium citrate. The cytochrome
b
1
and total iron content, and the measurement of the uptake of
55
Fe
3+
, indicate an impairment of the enterochelin-dependent iron transport system. The growth response to sodium citrate is related to the presence, in strain AN102, of an inducible citrate-dependent iron transport system.
Utilization of Glucose in Heterotrophic Media by
Thiobacillus intermedius
Authors: Matin Abdul , Rittenberg Sydney C.
Published: January 2020

The growth yield of
Thiobacillus intermedius
is greater in glucose-yeast extract or glucose-casein hydrolysate broth than in comparable media without glucose. The quantity of glucose utilized in the glucose-supplemented media is much greater than the increase in cell yield observed relative to the unsupplemented media. Addition of glucose to cell-free extracts of glucose-yeast extract or glucose-casein hydrolysate grown cells results in the reduction of endogenous cytochrome
c
. Thus, in these media, glucose serves as a source of energy. This is in contrast to thiosulfate-glucose broth in which glucose provides only cell carbon. The presence of thiosulfate in glucose-casein hydrolysate broth results in a marked decrease in glucose consumption. Cytochrome
c
in extracts of cells grown in this medium is not reduced by glucose addition. The data suggest that thiosulfate prevents the utilization of glucose for energy generation. The final growth yield in glucose-casein hydrolysate broth is directly proportional to the initial glucose concentration, although not all the glucose was utilized even at the lowest concentration tested. This effect may be due to an inefficient glucose transport in this organism.