bluuebunny/crossref_metadata_2025 huggingface dataset:
Induction of Superoxide Dismutase by Molecular Oxygen
Authors: Gregory Eugene M. , Fridovich Irwin
Published: January 2020

Oxygen induces superoxide dismutase in
Streptococcus faecalis
and in
Escherichia coli B. S. faecalis
grown under 20 atm of O
2
had 16 times more of this enzyme than did anaerobically grown cells. In the case of
E. coli
, changing the conditions of growth from anaerobic to 5 atm of O
2
caused a 25-fold increase in the level of superoxide dismutase. Induction of this enzyme was a response to O
2
rather than to pressure, since 20 atm of N
2
was without effect. Induction of superoxide dismutase was a rapid process, and half of the maximal level was reached within 90 min after N
2
-grown cells of
S. faecalis
were exposed to 20 atm of O
2
at 37 C.
S. faecalis
did not contain perceptible levels of catalase under any of the growth conditions investigated by Stanier, Doudoroff, and Adelberg (23), and the concentration of catalase in
E. coli
was not affected by the presence of O
2
during growth.
S. faecalis
, which had been grown under 100% O
2
and which therefore contained an elevated level of superoxide dismutase, was more resistant of 46 atm of O
2
than were cells which had been grown under N
2
.
E. coli
grown under N
2
contained as much superoxide dismutase as did
S. faecalis
grown under 1 atm of O
2
. The
E. coli
which had been grown under N
2
was as resistant to the deleterious effects of 50 atm of O
2
as was
S. faecalis
which had been grown under 1 atm of O
2
. These results are consistent with the proposal that the peroxide radical is an important agent of the toxicity of oxygen and that superoxide dismutase may be a component of the systems which have been evolved to deal with this potential toxicity.
Characterization of the Polydisperse Closed Circular Deoxyribonucleic Acid Molecules ofBacillus megaterium
Authors: Henneberry R. C. , Carlton Bruce C.
Published: January 2020

The polydisperse circular deoxyribonucleic acid (DNA) molecules which comprise up to 30% of the total extractable DNA ofBacillus megateriumstrain 216 have been purified and partially characterized. Banding in cesium chlorideethidium bromide by “gradient relaxation” in a fixed-angle rotor provided good resolution of circular and chromosomal DNAs for preparative separations. Renaturation studies on purified circular DNA failed to reveal a rapidly renaturing fraction, and DNA-DNA hybridization studies indicated that the majority of the chromosomal nucleotide sequences are represented in the heterogeneous-size population of circular molecules. It is concluded that the circular DNA ofB. megateriumdoes not represent typical bacterial plasmid DNA. The possibility that the circular DNA molecules are the result of the expression of a defective bacteriophage is discussed.
Regulation of
argE-argH
Expression with Arginine Derivatives in
Escherichia coli
: Extreme Non-uniformity of Repression and Conditional Repressive Action
Authors: Bollon Arthur P. , Vogel Henry J.
Published: January 2020

In regulatory studies of the arginine biosynthetic system of
Escherichia coli
, α-
N
-acetyl-
l
-arginine (AcA) is a useful restrictive arginine source. In strain 39A-23R3 (
argA
−
), at 25 μg/ml, AcA gives suboptimal growth rates and is fully derepressive for acetylornithinase (specified by
argE
) and approximately 50% derepressive for argininosuccinase (specified by
argH
). At 10 μg/ml, the growth rate decreases, whereas the extent of derepression is unchanged; at 500 μg/ml, full repression results. In strain 3670 (
argB
−
argG
−
), AcA (25 μg/ml) leads to partial derepression of acetylornithinase but full repression of argininosuccinase. Thus, the repression patterns for both strains, although not identical, are nonuniform. AcA utilization is antagonized by α-
N
-acetyl-
l
-ornithine (AcO). In strain 3670 (blocked before and after acetylornithinase), the growth rate on AcA (25 μg/ml) is lowered by AcO (500 μg/ml); acetylornithinase is completely derepressed, whereas argininosuccinase is fully repressed. This difference in regulatory behavior represents extreme nonuniform repression. Unexpectedly, the effect of AcO is attributable to the conversion of AcO to citrulline (Cit). In strain 3670, mixtures of AcA (25 μg/ml) and Cit (300 μg/ml) permit complete derepression of acetylornithinase; there is evidence that Cit enters the cell. In contrast, in the arginine-limited chemostat, Cit represses acetylornithinase. These opposite regulatory effects of Cit appear to stem from the difference in arginine restriction. AcA enters the cell via AcO permease and is deacylated by acetylornithinase (

K
m

, 5.0 mM). AcA competitively inhibits AcO cleavage (

K
i

, 2.4 mM), but Cit is not inhibitory. The antagonism of AcA utilization by AcO or Cit is thought to be exerted at the AcO permease.
Role of Intestinal Microflora in the Metabolism of Guanidinosuccinic Acid
Authors: Milstien Sheldon , Goldman Peter
Published: January 2020

Among a variety of bacteria isolated from the gastrointestinal tracts of rats and humans, only streptococci of group N are capable of degrading guanidinosuccinic acid added to their culture medium. The urinary excretion of guanidinosuccinic acid by germfree rats is greater than that of conventional rats. The excretion of this compound by gnotobiotic rats correlates with the capacity of their intestinal microflora to degrade guanidinosuccinic acid in culture. Thus, guanidinosuccinic acid excretion is low in rats infected exclusively with
Streptococcus faecalis
, and the excretion is not altered when germfree rats are infected with an organism unable to degrade guanidinosuccinic acid (
Lactobacillus
). These findings suggest that the intestinal microflora, particularly
Streptococcus
, play a role in the metabolism of guanidinosuccinic acid by the host.
Changes in Cell Size and Shape Associated with Changes in the Replication Time of the Chromosome ofEscherichia coli
Authors: Zaritsky A. , Pritchard R. H.
Published: January 2020

Average cell mass is shown to be inversely related to the concentration of thymine in the growth medium of athy−strain ofEscherichia coli. The kinetics of the transition from one steady-state average cell mass to another was followed in an attempt to determine the relationship between the chromosome replication time and the time between completion of a round of chromosome replication and the subsequent cell division. Differences in average cell mass are shown to be associated with similar differences in average cell volume. Changes in volume associated with changes in thymine concentration are shown to be due primarily to differences in the width of cells. It is proposed that extension in length of the cell envelope occurs at a linear rate which is proportional to the growth rate and which doubles at the time of termination of rounds of replication. Changes in volume not associated with a change in growth rate are therefore accommodated by a change in cell width. Conditions are described under which average cell mass can continue to increase in successive generations and no steady-state average cell mass is achieved.
A Paracrystalline Inclusion Formed During Sporulation of Enterotoxin-Producing Strains of
Clostridium perfringens
Type A
Authors: Duncan Charles L. , King Gretchen J. , Frieben William R.
Published: January 2020

A large paracrystalline inclusion is formed by certain strains of
Clostridium perfringens
type A during spore morphogenesis. In most cell thin sections, the inclusion appeared rod-shaped when sectioned at an angle perpendicular to its longer axis, and circular or oval-shaped when sectioned at an angle parallel to its longer axis. Measurements performed on electron micrographs of inclusions sectioned to reveal the rod shape indicated a fairly consistent thickness (width) of 192 ± 23 nm. The length of the inclusions varied considerably with a maximum of approximately 2,120 nm being observed. Ultrastructurally, the inclusion was composed of closely packed, periodically spaced, parallel layers. Usually a single inclusion was randomly located in the cytoplasm of the cell. Two inclusions per cell were rarely observed. The inclusion was formed only by ent
+
strains of
C. perfringens
. Mutants of the ent
+
strain NCTC 8798 that were altered in their sporulating and enterotoxin-producing capacities and revertants of these mutants were tested for inclusion formation. The results indicate that, as with the ent
+
trait, a direct relationship exists between inclusion formation and spore formation. The synthesis of enterotoxin, formation of a morphologically distinct inclusion, and the initial deposition of discontinuous coat fragments around the forespore appear to be events closely related in time during spore morphogenesis.
Deoxyribonucleic Acid Synthesis and Deoxynucleotide Metabolism During Bacterial Spore Germination
Authors: Setlow Peter
Published: January 2020

Deoxyribonucleic acid (DNA) synthesis during germination of
Bacillus megaterium
spores takes place in two stages. In stage I (0-55 min) DNA synthesis is slow and there is no detectable net synthesis, whereas in stage II (from 55 min on) the rate of synthesis is much faster and net DNA synthesis occurs. Deoxyribonucleotide pool sizes match the rates of DNA synthesis in stages I and II. The level of deoxyribonucleotide triphosphates is not correlated with the level of deoxyribonucleotide kinases, but rather with that of ribonucleotide reductase activity.
Reconstitution of Nitrate Reductase Activity and Formation of Membrane Particles from Cytoplasmic Extracts of Chlorate-Resistant Mutants of
Escherichia coli
Authors: MacGregor C. H. , Schnaitman C. A.
Published: January 2020

The reconstitution of nitrate reductase activity in mixtures of cytoplasmic fractions from the chlorate-resistant mutants
chlA, B, C
, and
E
which are lacking this activity was investigated, and the membrane-like particulate material which formed during this reconstitution was analyzed by polyacrylamide gel electrophoresis. When
chlA
and
chlB
extracts are incubated together, the cytoplasmic membrane proteins present in the particles which are formed are contributed by both mutants, and the proteins are essentially the same as the proteins in the cytoplasmic membrane fractions of the two mutants. Identical amounts of protein become particulate when cytoplasmic extracts of any of the mutant strains or wild-type strains are incubated at 32 C either singly or in mixtures, and the formation of particulate material does not appear to be a consequence of nitrate reductase reconstitution. Experiments with wild-type strains indicate that the membrane proteins in the cytoplasmic extract are derived from the cytoplasmic membrane during cell breakage. Reconstitution experiments involving various combinations of preincubated and unincubated extracts of the mutants have allowed a preliminary identification of three types of components which are necessary for the formation of active nitrate reductase: (i) a soluble factor present only in extracts from induced
chlB;
(ii) a different soluble factor which is missing in
chlB
but is present in extracts from wild-type,
chlA, chlC
, and
chlE;
and (iii) a complex including the nitrate reductase protein which is inactivated by preincubation of the mutant extracts.
Relationship of a Wall-Associated Enzyme with Specific Layers of the Cell Wall of a Gram-Negative Bacterium
Authors: Costerton J. W.
Published: January 2020

In untreated cells of the marine pseudomonad studied here, alkaline phosphatase was found to be located in the periplasmic space, at the cell surface, and in the medium into which it had been shed during growth. Washing in 0.5 M NaCl, which removed the loosely bound outer layer, caused a shift of periplasmic enzyme to the outer aspect of the double-track layer and released some of the cell surface-associated enzyme. When the double-track layer of the cell wall was partially deranged, large amounts of this cell wall-associated enzyme were released, and, when the double-track was removed from the cells to produce mureinoplasts, alkaline phosphatase was released into the menstruum. There was no significant association of the enzyme with the peptidoglycan layer of the cell wall, which is the outermost structure of the mureinoplast, and no association of the enzyme with the cytoplasmic membrane of these modified cells. This study has shown that alkaline phosphatase is specifically associated with the outer layers of the cell walls of cells of this organism and is retained within the cell wall by virtue of this association.
Microflora of Soil as Viewed by Freeze-Etching
Authors: Balkwill D. L. , Casida L. E.
Published: January 2020

The indigenous microflora of soil were released from the soil materials and concentrated without the occurrence of growth by use of a blending-simple centrifugation procedure. The cell concentrate was then frozen-etched and viewed by transmission electron microscopy. Criteria were established for detecting microbial cells among the residual soil debris. The freeze-etching of the soil cell concentrate provided results on cell size distributions in agreement with those obtained by thin sectioning. However, the blending-simple centrifugation procedure for cell release and concentration from soil allowed the observation of large cells (≥1.0 μm in diameter) which apparently are missed by the “exhaustive centrifugal washing” cell separation-concentration procedure. The procedure of blending-simple centrifugation combined with the viewing of frozenetched preparations allowed evaluations of the soil microflora for cellular diameters, length-width ratios, shapes, and structure.
Surface Structure of Gliding Bacteria After Freeze-Etching
Authors: Burchard Robert P. , Brown Dennis T.
Published: January 2020

Ultrastructural studies of gliding bacteria demonstrate 10- to 11-nm beads on the inner surface of the outer bilayer of
Cytophaga columnaris
. These were not found in
Myxococcus xanthus
. On treatment with glutaraldehyde and ethanol, the beads appear in linear arrays.
R-Factor-Mediated Resistance to Tetracycline in
Proteus mirabilis
Authors: Franklin T. J. , Rownd R.
Published: January 2020

The expression of R-factor-mediated resistance to tetracycline has been compared in
Proteus mirabilis
and
Escherichia coli
. Resistance to a range of concentrations of tetracycline was significantly lower in
P. mirabilis
than in
E. coli
in both induced and repressed states. Indirect evidence showed that conditions which result in a marked increase in the level of resistance of
P. mirabilis
harboring the R factor
NR1
to chloramphenicol, streptomycin, and spectinomycin due to an amplification in the number of copies of r-determinants per cell do not detectably increase the level of resistance to tetracycline. Tetracycline resistance was inducible in early stationary-phase
P. mirabilis NR1
although not after 5 h in this state. Double isotope labeling of control and tetracycline-induced
P. mirabilis NR1
in early stationary phase revealed isotopic enrichment of certain peaks in extracts from induced cells subjected to polyacrylamide gel electrophoresis.
Peptidoglycan of Free-Living Anaerobic Spirochetes
Authors: Joseph R. , Holt S. C. , Canale-Parola E.
Published: January 2020

Electron microscope examination of negatively stained or thin-sectioned cells of
Spirochaeta stenostrepta
treated with penicillin or lysozyme showed that the peptidoglycan was present as a thin, electron-dense layer adjacent and external to the cytoplasmic membrane. The peptidoglycan was isolated from cells of
S. stenostrepta
and
Spirochaeta litoralis
by a procedure including treatments with sodium lauryl sulfate and Pronase. Hydrolysates of the isolated
S. stenostrepta
and
S. litoralis
peptidoglycans contained glucosamine, muramic acid, glutamic acid,
l
-ornithine, and alanine in molar ratios of 0.90:0.85:1.00:1.00:1.40 and of 0.63:0.63:0.99:1.00:1.41, respectively. Determination of N-terminal residues suggested that nearly 50% of the ornithine in
S. stenostrepta
and
S. litoralis
peptidoglycans was involved in peptide cross-linkage. The peptidoglycan layer of
S. stenostrepta
was sensitive to lysozyme and myxobacter AL-1 protease.
Uptake and Utilization of Glutamic Acid by
Cryptococcus albidus
Authors: Tang S. L. , Howard D. H.
Published: January 2020

Cryptococcus albidus
utilizes glutamate as a sole carbon source. The kinetics of uptake of this amino acid were studied.
l
-Glutamic acid was taken up by two saturable systems: a high affinity system with a Michaelis constant (

K
m

) of 1.15 × 10
−5
M and a

V
max

of 0.049 μmol per mg per h and a low affinity system with a

K
m

of 2.5 × 10
−3
M and a

V
max

of 3.61 μmol per mg per h. Both systems possessed characteristics of active transport which were dependent on temperature and pH and which required metabolic energy. Uptake was inhibited at 37 C but the temperature-sensitive step was reversible. Chemical fractionation of cells with 5% trichloroacetic acid showed that glutamic acid initially entered a soluble pool which decreased after 1 h as the amino acid was incorporated into the protein and nucleic acid fractions of the yeast. Some of the glutamate was completely oxidized and could be recovered as
14
CO
2
. Therefore, the amino acid was also used as an energy source.
Polyamine Requirements of a Conditional Polyamine Auxotroph of
Escherichia coli
Authors: Munro George F. , Bell Carol A.
Published: January 2020

Escherichia coli
MA-159 is deficient in agmatine ureohydrolase. After addition of exogenous arginine, the cellular putrescine content declines immediately and exponentially; however, the spermidine content remains normal for 3 h. The growth rate of such cultures, measured turbidometrically, slows gradually over many hours. Putrescine-depleted cultures grow especially slowly in media of low osmolarity, whereas nondepleted cultures grow at similar and rapid rates in media of either normal or low osmolarity. External osmolarity also affects the ability of various exogenous polyamines to stimulate growth of putrescine-depleted cultures. In medium of normal osmolarity, putrescine and spermidine both allow sustained rapid growth for many hours. In low osmolarity medium, putrescine allows sustained rapid growth, whereas cultures containing spermidine grow more slowly; this result cannot be explained by conversion of putrescine to spermidine, for cultures grown with exogenous putrescine contain smaller spermidine pools than do cultures grown with exogenous spermidine. Spermine greatly stimulates growth in medium of normal osmolarity; however, in medium of low osmolarity, spermine is much less effective and can block the action of putrescine. Several other polyamines have been studied in this system. These results confirm and expand previous reports that polyamines are necessary for growth of
E. coli
and suggest that putrescine may have a specific function during growth in media of low osmolarity.
Effects of Phagocytosis by Rabbit Granulocytes on Macromolecular Synthesis and Degradation in Different Species of Bacteria
Authors: Elsbach Peter , Pettis Penelope , Beckerdite Susan , Franson Richard
Published: January 2020

Phagocytosis and killing of gram-positive
Bacillus megaterium
and
Micrococcus lysodeikticus
by granulocytes in vitro is associated with almost immediate cessation of bacterial protein synthesis. By contrast, protein synthesis by
Escherichia coli
continues after ingestion and killing. After preincubation of
E. coli
with intact granulocytes for 15 min, when 95% or more of the bacteria can no longer multiply, induction of β-galactosidase proceeds at rates about half of control values. With disrupted granulocytes, which kill
E. coli
as rapidly as intact cells, the rate of induction of β-galactosidase does not fall until after 30 min of preincubation. We attribute the different effects of phagocytosis on the biochemical apparatus of these microorganisms to the different fates of their envelopes. Specifically labeled protein, ribonucleic acid, deoxyribonucleic acid, and lipid of all three species of bacteria and peptidoglycan of
E. coli
are apparently incompletely degraded during phagocytosis. However, the cell walls of
M. lysodeikticus
and
B. megaterium
undergo rapid and almost complete degradation. The resulting structural disintegration of these gram-positive microorganisms must cause extensive biochemical disorganization as well. Our evidence indicates that the
E. coli
envelope, on the other hand, retains sufficient structural organization to preserve integrated biochemical function for at least 1 h after the bacteria have lost the ability to multiply.
Guanosine Diphosphate-
l
-Fucose Glycopeptide Fucosyltransferase Activity in
Corynebacterium insidiosum
Authors: Sadowski Peter L. , Strobel Gary A.
Published: January 2020

The biosynthesis of a phytotoxic glycopeptide of
Corynebacterium insidiosum
involves guanosine diphosphate-
l
-fucosyltransferase activity. This enzyme activity is most consistently associated with the cellular membranes fraction. The optimal pH for the transfer reaction is 7.5. The partially hydrolyzed toxin serves as an acceptor (primer) of
l
-fucose.
Derepression of Uridine Diphosphate-Glucose Pyrophosphorylase (
galU
) in
capR
(
lon
),
capS
, and
capT
Mutants and Studies on the
galU
Repressor
Authors: Buchanan Christine E. , Markovitz Alvin
Published: January 2020

Mutation of the
capR
(
lon
),
capS
, or
capT
genes in
Escherichia coli
K-12 causes overproduction of capsular polysaccharide leading to a mucoid phenotype. Several of the enzymes involved in capsular polysaccharide synthesis are derepressed in
cap
mutants. Previously it was shown that uridine diphosphate-glucose (UDPG) pyrophosphorylase, an enzyme involved in the synthesis of three of the nucleotide sugar precursors of the capsule, is derepressed in
capR
mutants. The control of
galU
, the gene which codes for UDPG pyrophosphorylase, is described in this study. In addition, it has been found that the enzyme is also derepressed in
capS
and
capT
mutants. The effect of
galU
gene dosage in
cap
mutants and the wild-type strain (all lysogenic for φ80) was studied by infecting them with the purified transducing phage φ80
dgalU
. The level of UDPG pyrophosphorylase increased in proportion to the number of
galU
copies added. The rate of enzyme synthesis in the mutants was about sixfold higher than in the wild type per
galU
gene added for multiplicities of infection from one to twenty. Thus, all the
galU
copies added to the wild-type lysogen were repressed. We obtain greater than 20
galU
copies per cell by infecting the nonlysogenic strain which allows multiplication of φ80
dgalU
. With some number of
galU
copies greater than 20, the rate of UDPG pyrophosphorylase synthesis in the wild type approaches the mutant rate of synthesis. The results suggest that there may indeed be a
galU
repressor pool in the cell which can be completely titrated. This pool must be composed of more than 20
galU
repressor molecules. Since the
capR
,
capS
, and
capT
gene products or combinations thereof are known to control other widely separated operons of the cell besides the
galU
gene, it is postulated that the
galU
repressor may be capable of binding other operators. This would account for the relatively large pool of
galU
repressors per cell.
tyrR, A Regulatory Gene of Tyrosine Biosynthesis in Salmonella typhimurium
Authors: Gollub E. G. , Liu K. P. , Sprinson D. B.
Published: January 2020

4-Fluorophenylalanine-resistant mutants of
Salmonella typhimurium
were isolated in which tyrosine pathway enzymes were not repressed by
l
-tyrosine. The mutants produced elevated levels of 3-deoxy-
d
-arabinoheptulosonic acid 7-phosphate (DAHP) synthetase (tyr) and chorismate mutase T-prephenate dehydrogenase, and these enzymes as well as transaminase A were not repressed by high concentrations of tyrosine. Genetic analysis revealed that a mutation in a gene designated
tyrR
was responsible for the constitutivity of the tyrosine pathway enzymes in strains SG1, SG7, and SG9, and that
tyrR
was linked to
pyrF
. In strain SG1 a mutation had also occurred in
aroF
, the structural gene for DAHP synthetase (tyr), resulting in loss of sensitivity of this enzyme to end-product inhibition. There appeared to be no relationship between loss of feedback inhibition and loss of end-product repression, since derivative strains of SG1 that carried only the
tyrR
mutation behaved like the singly mutated
tyrR
strains, SG7 and SG9, in showing high constitutive levels of tyrosine-specific enzymes that were not repressed by tyrosine.
Use of Cobalt as a Mitochondrial Vital Stain to Study Cytoplasmic Exchange in Matings of the Basidiomycete
Schizophyllum commune
Authors: Watrud Lidia S. , Ellingboe Albert H.
Published: January 2020

Differential labeling of mates, based on the selective uptake of cobalt by mitochondria of one of the partners, has been used to determine visually by means of phase-contrast microscopy whether transfer of mitochondria occurs after hyphal fusion. Compatible and incompatible matings of the tetrapolar basidiomycete,
Schizophyllum commune
, were studied. Transfer was detectable in common-
A
, common-
AB
, and fully compatible matings. It was not detectable in common-
B
matings
Characteristics of Deoxyribonucleic Acid Polymerase Isolated from Spores of
Rhizopus stolonifer
Authors: Gong Cheng-Shung , Dunkle Larry D. , Van Etten James L.
Published: January 2020

Deoxyribonucleic acid (DNA)-dependent DNA polymerase was purified several hundredfold from germinated and ungerminated spores of the fungus
Rhizopus stolonifer
. The partially purified enzymes from both spore stages exhibited identical characteristics; incorporation of [
3
H]deoxythymidine monophosphate into DNA required Mg
2+
, DNA, a reducing agent, and the simultaneous presence of deoxyguanosine triphosphate, deoxycytidine triphosphate, and deoxyadenosine triphosphate. Heat-denatured and activated DNAs were better templates than were native DNAs. The buoyant density of the radioactive product of the reaction was similar to that of the template DNA. The enzyme is probably composed of a single polypeptide chain with an
S
value of 5.12 and an estimated molecular weight of 70,000 to 75,000. During the early stages of purification, the enzyme fraction from ungerminated spores required exogenous DNA for maximum activity, whereas the corresponding enzyme fraction from germinated spores did not require added DNA. Apparently DNA polymerase from germinated spores was more tightly bound to endogenous DNA than was the enzyme from ungerminated spores.
Cytoplasmic “Petite” Induction in Recombination-Deficient Mutants of
Saccharomyces cerevisiae
Authors: Moustacchi Ethel
Published: January 2020

As compared to the original wild type, the induction of the cytoplasmic “petite” mutation by ultraviolet light and by the intercalating dye, ethidium bromide, is reduced in two mutants (
rec4
and
rec5
) of
Saccharomyces cerevisiae
. These mutants are blocked in X rays or ultraviolet light-induced intragenic recombination. It then appears that the products of nuclear genes necessary for the completion of nuclear intragenic recombination events are also involved in steps of the metabolic chain which leads to the mitochondrial mutation, ρ
−
.
Inhibitors of Ribonucleic Acid Synthesis in
Saccharomyces cerevisiae
: Decay Rate of Messenger Ribonucleic Acid
Authors: Tønnesen T. , Friesen J. D.
Published: January 2020

Daunomycin and ethidium bromide, two deoxyribonucleic acid-intercalating drugs, inhibit ribonucleic acid (RNA) and protein synthesis in
Saccharomyces cerevisiae
. Both agents rapidly curtail uptake of radioactive adenine, whereas the kinetics of radioactive leucine uptake after drug addition are consistent with translation of a pool of exponentially decaying messenger RNA. Messenger RNA half-life determinations from these experiments gave identical results over a range of drug concentrations; this value is 21 ± 4 min at 30 C. In a temperature-sensitive mutant in which RNA synthesis is curtailed at the nonpermissive temperature, a similar half-life for messenger RNA decay is found both in the absence and in the presence of either drug. This indicates that at the concentrations used in this study, neither daunomycin nor ethidium bromide has an appreciable direct effect on translation and do not increase the lability of messenger RNA.
Identification of Prenol Intermediates of Wall Biosynthesis in Growing Cells of
Lactobacillus plantarum
Authors: Thorne Kareen J. I.
Published: January 2020

The incorporation of
14
C-mevalonic acid by
Lactobacillus plantarum
predominantly into C
55
prenol made it possible to determine the distribution of
14
C-prenol between all its derivatives. In logarithmic-phase cells, 25% of the prenol was free, 31% was as monophosphate, 4% as pyrophosphate, 12% as peptidoglycan precursor, and 28% as glyco-phospho-prenol. The glyco-phospho-prenol contained rhamnose, and probably glucose, galactose, and ribitol phosphate, and it may, therefore, be involved in polysaccharide and teichoic acid biosynthesis. The proportion of free prenol increased, up to 73%, as the cell culture aged. Free prenol was also formed when cells were incubated in buffer. The free prenol was readily reutilized when cells were returned to growth medium.
Duplication-Translocations of Tryptophan Operon Genes in
Escherichia coli
Authors: Jackson Ethel Noland , Yanofsky Charles
Published: January 2020

Mutants of
Escherichia coli
were selected in which a single mutational event had both relieved the polar effect of an early
trpE
mutation on
trpB
and simultaneously released the expression of
trpB
from tryptophan repression. The frequency at which these mutations appeared was roughly equal to the frequency of point mutations. In each of these mutants, the mutation increased the function of
trpB
and also increased the activity of some, but not all, of the other four tryptophan operon genes. Genetic analysis showed that the mutations were not located within the
trp
operon since in each case the parental
trp
operon could be recovered from the mutants. Each mutant was shown to carry a duplication of a
trp
operon segment translocated to a new position near the
trp
operon. Polarity is relieved since the
trpB
duplication-translocation is not in the same operon as the
trpE
polar mutation. The duplicated and translocated segments are fused to operons not regulated by tryptophan, so
trpB
function is no longer subject to tryptophan repression. The properties of the mutants indicate that the length of the duplicated segment and the position to which it is translocated differ in each of the seven mutants studied. The duplications are unstable, but the segregation pattern observed is not consistent with a single crossover model for segregation. That such duplication-translocation events generate a variety of new genetic arrangements at a frequency comparable with point mutations suggests they may play an important role in evolution.
Deoxyribonucleic Acid Methylation and Development in
Caulobacter bacteroides
Authors: Degnen Suzanne T. , Morris N. Ronald
Published: January 2020

The stalked bacterium
Caulobacter bacteroides
, which displays a series of developmental changes during its life cycle, was shown to contain the methylated deoxyribonucleic acid (DNA) nucleotide bases N
6
-methyladenine and 5-methylcytosine as well as the enzymes required for the synthesis of these bases. A difference in the specific activity of these enzymes was observed between swarmer cells, which are low in activity, and stalked cells, which are high in activity. This difference was not reflected in the methylation patterns in the DNA of the two cell types since
C. bacteroides
DNA is essentially completely methylated with respect to
C. bacteroides
methylases.
Osmotically Induced Excretion of Putrescine by Mutants of
Escherichia coli
Defective in Potassium Transport
Authors: Munro George F. , Sauerbier Walter
Published: January 2020

Escherichia coli
is known to excrete putrescine rapidly after a sudden elevation in the osmolarity of the medium. We report here that mutants defective in the transport of potassium ions display a greatly diminished rate of [
14
C]putrescine excretion.
Isolation and Characterization of a Mutant of
Salmonella typhimurium
Deficient in a Major Deoxyribonucleic Acid Polymerase Activity
Authors: Whitfield Harvey J. , Levine Gary
Published: January 2020

A mutant of
Salmonella typhimurium
strain LT2 that is deficient in a major deoxyribonucleic acid (DNA) polymerase activity has been isolated and characterized. This mutant resembles the
pol
mutants of
E. coli
in that it has low DNA polymerase activity and it is sensitive to methyl methane sulfonate as well as ultraviolet irradiation. Revertants selected for methyl methane sulfonate resistance are no longer sensitive to ultraviolet irradiation and contain normal DNA polymerase levels. No direct role in replication can be ascribed to this polymerase activity since cells grow well in its absence. In addition, the LT2 plasmid has been shown to exist in the mutant strain.
Deletion Map of the Chloramphenicol Resistance Region of R1 and R100-1
Authors: Foster T. J. , Howe T. G. B.
Published: January 2020

Recombination between single-site and multisite chloramphenicol-sensitive mutants of the F-like R factors R1 and R100-1 indicates that the chloramphenicol resistance region is a single structural gene coding for the 20,000-molecular weight subunit of chloramphenicol acetyltransferase.
Relationship Between Transformation in
Bacillus subtilis
and Infection by Bacteriophage SP02
Authors: Stewart Charles R. , Pagel M. Frances
Published: January 2020

When bacteriophage SP02 infects a
Bacillus subtilis
culture during or shortly after transformation, the frequency of transformants among the resulting lysogens is greatly reduced relative to that in the uninfected culture. The effect can occur after the deoxyribonucleic acid has been taken up and covalently attached to recipient deoxyribonucleic acid.
Isolation and Characterization of φ80 Transducing Bacteriophage for a Ribonucleic Acid Polymerase Gene
Authors: Konrad Bruce , Kirschbaum Joel , Austin Stuart
Published: January 2020

A new method for isolating specialized transducing phages is described. It was used to isolate a group of φ80 transducing phages which carry various bacterial markers from the
metB
region of the
Escherichia coli
chromosome. Some of the phages selected for transduction of the
supA36
marker were also shown to carry
rif
, a locus known to specify the β subunit of ribonucleic acid polymerase. Expression of the prophage
rif
r
gene in lysogens was demonstrated by its ability to confer rifampin resistance on part of the cellular ribonucleic acid polymerase pool.
Influence of Polyamine Limitation on the Chain Growth Rates of β-Galactosidase and of Its Messenger Ribonucleic Acid
Authors: Morris David R. , Hansen Mogens T.
Published: January 2020

The rates of elongation of β-galactosidase and its messenger ribonucleic acid (RNA) were estimated in a polyamine-deficient mutant of
Escherichia coli
through an analysis of the kinetics of enzyme induction. The chain growth of β-galactosidase was calculated from the time required after the appearance of an amino terminal fragment of 60 amino acids (auto-α) until completed enzyme began to accumulate. The elongation rate of β-galactosidase messenger RNA was estimated from the time after induction at which streptolydigen-resistant, enzyme-forming capacity first appeared. Upon polyamine starvation, the rate of polypeptide elongation slowed from 17 to 10 amino acids per s and the messenger RNA elongation rate decreased from 47 to 30 nucleotides per s. These reductions in polymerization rates were proportional to the decrease in cellular growth rate produced by polyamine starvation. It was concluded that, although it is quite unlikely that polyamine levels are involved in regulation of cell growth, they may be acting as cofactors in the synthesis of RNA or protein, or both.
Regulation of Exocellular Proteases in
Neurospora crassa
: Role of
Neurospora
Proteases in Induction
Authors: Drucker H.
Published: January 2020

Cells of
Neurospora crassa
strain 74A, grown on sucrose for 12 h and transferred to a medium containing protein as sole carbon source, would not produce exocellular protease in significant amounts. When a filtrate from a culture induced to make protease by normal growth on a medium containing protein as principal carbon source was added to an exponential-phase culture in protein medium, exocellular protease was made in amounts similar to those made during normal induction. The material in the culture filtrate that participated in the induction process was identified as protease by its heat lability, molecular weight, and the dependence of induction rate on units of proteolytic activity added to the exponential-phase culture. Induction of the formation of exocellular protease by exponential-phase cells appears to require a protein substrate, added proteolytic activity, and protein synthesis. The protease produced by induced exponential-phase cells was as efficient in promoting induction as normally induced enzyme, whereas constitutive intracellular enzyme was only 50% as efficient. The bacterial protease thermolysin was able to induce exocellular protease at 90.7% of the rate observed with added
N. crassa
exocellular protease.
Regulation of Leucine Biosynthesis in
Bacillus subtilis
Authors: Ward Jonathan B. , Zahler Stanley A.
Published: January 2020

The biosynthesis of α-isopropylmalate (αIPM) synthetase, IPM isomerase, and βIPM dehydrogenase in
Bacillus subtilis
can be derepressed in leucine auxotrophs by limiting them for leucine. The derepression of the three enzymes is apparently coordinate. A class of mutants resistant to 4-azaleucine excretes leucine and has derepressed levels of all three enzymes. The azaleucine-resistance mutations may lie in a gene (
azlA
) encoding a repressor. Efforts to find mutations characteristic of a constitutive operator have been unsuccessful. No polar mutations have been found among nine leucine auxotrophs that have characteristics of frameshift mutations. The enzyme catalyzing the first step in leucine biosynthesis, αIPM synthetase, is sensitive to feedback inhibition by leucine. We conclude that leucine biosynthesis is controlled by the inhibition of the activity of the first biosynthetic enzyme by leucine, and by the repression of the synthesis of the first three biosynthetic enzymes by leucine. The repression of the three enzymes may be under the control of a single repressor and a single operator, or of a single repressor and a separate operator for each structural gene.
Comparison of the Activities of Extracts of
Escherichia coli
and
Salmonella typhimurium
in Amino Acid Incorporation
Authors: Bassel B. A. , Curry M. E.
Published: January 2020

We have compared the amino acid incorporating activities of extracts of
Escherichia coli
and
Salmonella typhimurium
in in vitro protein-synthesizing systems directed by bacterial messenger ribonucleic acid (mRNA) of both species and by the genomes of coliphages Qβ and f2.
E. coli
and
S. typhimurium
extracts translate both homologous and heterologous bacterial mRNAs at comparable rates.
S. typhimurium
extracts translate phage RNAs only 10 to 15% as fast as
E. coli
extracts do. The presence of glucose in the growth medium increases the activity of
S. typhimurium
extracts three- to fourfold in the phage RNA-directed systems. Glucose has a much more limited effect on the activities of
E. coli
extracts. We show that similar amounts of phage RNA-ribosome complexes are formed in both the
E. coli
and the
S. typhimurium
systems, indicating that the different activities observed may be attributed to different rates of peptide elongation or to the formation of complexes at different sites on the RNA strand.
Studies on the Enzymes Involved in the Biosynthesis of Cyclo-Tris (
N
-2,3-Dihydroxybenzoyl-
l
-Seryl) in
Escherichia coli
: Kinetic Properties of the
l
-Serine–Activating Enzyme
Authors: Bryce Graeme F.
Published: January 2020

Some kinetic properties of the formation of a thioester-bound
l
-seryl-enzyme intermediate are described. The rate constant of formation is 3.12 × 10
2
M
−1
s
−1
and the rate constant for spontaneous breakdown is 2.47 × 10
−3
s
−1
. These constants yield a value of log
K
= 5.10 for the overall equilibrium constant which agrees favorably with a value of 5.20 calculated from equilibrium binding data. E
1
·serine formation requires a thiol group which is extremely reactive to
N
-ethylmaleimide; the second-order rate constant for enzyme inactivation by this reagent is 77.1 M
−1
s
−1
at pH 6.6 and 0 C. Excess
l
-serine does not protect the enzyme against inactivation. In addition to an adenosine triphosphate-[
32
P]-inorganic pyrophosphate exchange, the enzyme also catalyzes an
l
-serine-dependent adenosine triphosphate-[
3
H]adenosine monophosphate exchange in accordance with the scheme proposed for the activation of serine.
Glucose and Pyruvate Metabolism of
Spirochaeta litoralis
, an Anaerobic Marine Spirochete
Authors: Hespell R. B. , Canale-Parola E.
Published: January 2020

The pathways of glucose and pyruvate metabolism in
Spirochaeta litoralis
, a free-living, strictly anaerobic marine spirochete, were studied. Addition of 0.2 to 0.4 M NaCl (final concentration) to suspending buffers prevented cell lysis and was necessary for gas evolution from various substrates by cell suspensions. The organism fermented glucose mainly to ethanol, acetate, CO
2
, and H
2
. Determination of radioactivity in products formed from
14
C-labeled glucose and assays of enzymatic activities in cell extracts indicated that
S. litoralis
catabolized glucose via the Embden-Meyerhof pathway. A clostridial-type clastic reaction was utilized by the spirochete to degrade pyruvate to acetyl-coenzyme A, CO
2
, and H
2
. Formation of acetate from acetyl-coenzyme A was catalyzed by phosphotransacetylase and acetate kinase. Nicotinamide adenine dinucleotide-dependent acetaldehyde and alcohol dehydrogenases converted acetyl-coenzyme A to ethanol. A reversible hydrogenase activity was detected in cell extracts.
S. litoralis
cell extracts contained a rubredoxin similar in spectral properties to other bacterial rubredoxins.
Mycological Applications of X-Ray Microanalysis
Authors: Thibaut M. , Ansel M.
Published: January 2020

In
Aspergillus fumigatus
, X-ray microanalysis applied in wavelength dispersive spectroscopy enabled us to detect the presence of calcium, potassium, sulfur, phosphorus, and magnesium; and in
A. niger
we detected the presence of calcium, potassium, chloride, sulfur, phosphorus, sodium, and magnesium. These various elements were identified by their K α lines.
Respiration of Wild Type and Extrachromosomal Mutants of
Neurospora crassa
Authors: Colvin H. J. , Sauer B. L. , Munkres K. D.
Published: January 2020

The specific rates of respiration of cells of wild type and four extrachromosomal mutants of
Neurospora crassa
were measured throughout the vegetative growth cycle. Two forms of respiration were observed: (i) cyanide sensitive; and (ii) cyanide resistant, salicyl hydroxamate sensitive. These two forms are called terminal and alternate, respectively. The former proceeds by the mitochondrial electron transfer chain and involves the cytochromes; the latter apparently proceeds by the initial portion of the electron transfer chain and does not involve cytochromes. Large and rapid changes of both the terminal and alternate respiratory activities occurred during the vegetative growth cycle. The kinetics of these changes in wild type were compared under some conditions which inhibit protein synthesis and others in which the nitrogen source was varied. The kinetics of the changes of the two forms of respiration of mutants differed from those normally exhibited by wild type, but with varied experimental conditions wild type could be made to resemble the mutants. The results of these studies are discussed in terms of a dynamic model of regulation of mitochondrial biogenesis in the coordination of the synthesis of mitochondrial proteins encoded by nuclear and mitochondrial genomes.
Defects in Prodigiosin Formation by L-Forms of
Serratia marcescens
Authors: Potter Clarence S. , Hubert Earl G. , Montgomerie John Z. , Kalmanson George M. , Guze Lucien B.
Published: January 2020

An L-form of
Serratia marcescens
has previously been shown incapable of producing the red pigment, prodigiosin, characteristic of the parent bacteria. Mutants of
S. marcesens
, unable to form one or the other of the two prodigiosin precursors, 4-methoxy-2,2′-bipyrrole-5-carboxaldehyde or 2-methyl-3-
n
-amylpyrrole, were used to test the nature of the L-form defect. The L-forms failed to form sufficient amounts of either precursor to be detected by the appropriate mutant, and, when furnished the precursors, failed to couple them to form prodigiosin.
Catabolism of
d
-Glucaric Acid to α-Ketoglutarate in
Bacillus megaterium
Authors: Sharma Brahma S. , Blumenthal Harold J.
Published: January 2020

Crude cell-free extracts of
d
-glucarate-grown cells of
Bacillus megaterium
converted
d
-glucarate to α-keto-β-deoxy-
d
-glucarate (KDG). Charcoal-treated cell-free extracts or partially purified enzyme preparations converted KDG to an intermediate which was isolated and identified as 2,5-diketoadipate (DKA). This compound was synthesized, and the cell-free extracts of
d
-glucarate grown cells were found to catalyze the reduction of nicotinamide adenine dinucleotide (NAD) in its presence. In the absence of NAD, the same enzyme preparation catalyzed the decarboxylation of the DKA to α-ketoglutarate semialdehyde (KGS), whereas in the presence of NAD the KGS was subsequently oxidized to α-ketoglutarate by α-ketoglutarate semialdehyde dehydrogenase. Since galactarate-grown
B. megaterium
contains a galactarate dehydrase forming KDG, the complete pathway for the metabolism of
d
-glucarate or galactarate to α-ketoglutarate and CO
2
is now known in a gram-positive bacterium.
Isolation, Chemical Composition, and Ultrastructural Features of the Cell Membrane of the Mycoplasma-Like Organism
Spiroplasma citri
Authors: Razin Shmuel , Hasin Miriam , Ne'eman Zvi , Rottem Shlomo
Published: January 2020

Thin sections of
Spiroplasma citri
, a mycoplasma-like organism isolated from citrus infected with “Stubborn” disease, showed the organisms to be limited by a single trilaminar plasma membrane. An additional outer layer could, however, be frequently seen in freeze-etched preparations of unwashed cells. The organisms were found to be extremely sensitive to lysis by osmotic shock. The cell membrane of
S. citri
isolated in this way resembled that of mycoplasmas in ultrastructure and gross chemical composition. The isolated membranes showed the characteristic trilaminar shape in section and the typical particle-studded fracture faces in freeze-etched preparations. Protein and lipid formed over 80% of the total dry weight of the membrane, which had a density of ~1.180 g/cm
3
. Cholesterol constituted over 20% of the total membrane lipid. Phosphatidyl-glycerol, synthesized by the organisms, was the major phospholipid. Significant amounts of hexosamine (15 to 35 μg/mg of membrane protein) could be found in the membrane preparations. Our results support the thesis that
S. citri
does not possess a cell wall, either of the gram-positive or the gram-negative type, though it may be coated by some other type of an envelope or by a slime layer, at least temporarily.
Effects of pH and Temperature on the Fatty Acid Composition of
Bacillus acidocaldarius
Authors: De Rosa M. , Gambacorta A. , Bu'lock J. D.
Published: January 2020

The fatty acid composition of lipid extracts from cells of
Bacillus acidocaldarius
grown at temperatures of 50 to 70 C and pH values of 2 to 5 was determined by gas chromatography of the methyl esters. The most abundant fatty acids are 11-cyclohexylundecanoic and 13-cyclohexyltridecanoic, followed by anteiso- and iso-heptadecanoic; unsaturated acids are absent. Highly aerated cultures produce more of the iso and anteiso acids and less of the cyclohexyl acids. The effects of temperature and pH are interdependent; at lower pH, increasing temperature raises the proportion of the iso and anteiso acids, but at higher pH the effect of increasing temperature is reversed and the proportion of the cyclohexyl acids is increased.