bluuebunny/crossref_metadata_2025 huggingface dataset:
Specific Effects of Heating of Transformable Streptococci on Their Ability to Discriminate Between Homospecific, Heterospecific, and Hybrid Deoxyribonucleic Acid
Authors: Ravin Arnold W. , Ma Michael
Published: January 2020

Heating competent bacteria of the Challis strain of
Streptococcus
at a temperature of 48 C causes them to lose their transformability and mainfest a slight retardation of growth rate without loss of viability. The heat-induced loss of transformability is due to diminution in the ability of the bacteria to bind deoxyribonucleic acid (DNA) irreversibly. Another effect of heat is upon a step in the transformation process subsequent to binding, a step in which DNA molecules will compete if they multiply infect an unheated cell. Despite the reduction in irreversible binding exhibited by heated cells, competition between DNA molecules to transform these cells is decreased. Neither of these sites affected by heat exhibits any specificity with regard to origin of DNA. Since heat treatment causes a relative stimulation of transformation by heterospecific DNA, a third effect of heat must be envisaged. The amount of heat-induced stimulation is dependent upon the amount of heterospecific material in the transforming DNA. Linkage of heterospecific markers is increased as a consequence of heating the recipients. Transformation by markers of different transforming efficiency in homospecific DNA is also affected by heat treatment in a differential manner. Taken together, these results point to a heat-sensitive intracellular mechanism that recognizes DNA base sequences during transformation. The effect of heat upon discrimination against heterospecific DNA has been found to occur also in the pneumococcus and in
Bacillus subtilis
.
Effect of Temperature on the Integrity of
Bacillus psychrophilus
Cell Walls
Authors: Mattingly Stephen J. , Best Gary K.
Published: January 2020

Cell walls isolated from
Bacillus psychrophilus
autolyse at temperatures which support growth. At temperatures above the maximum growth temperature (28 C), a nonenzymatic lysis occurs. Removal of autolytic enzyme activity with 10
m
LiCl had little effect on the rate or extent of lysis at elevated temperatures (37 and 45 C). Nonenzymatic lysis was characterized chemically by a decrease in the liberation of
N
-terminal groups, and the effects of
p
H, Ca
2+
, and ethylenediaminetetraacetic acid suggest that ionic linkages are involved in much of the integrity of the cell wall of this psychrophile. The nonenzymatic absorbance decrease at 45 C can be reversed to the extent of 70 to 100% at 0 C. Centrifugation of a heat-lysed wall suspension separated a soluble protein component which is required for low-temperature reaggregation. Preliminary evidence indicates the insoluble residue which remains after temperature-mediated lysis is primarily peptidoglycan.
Interaction of Concanavalin A with the Cell Wall ofBacillus subtilis
Authors: Doyle R. J. , Birdsell D. C.
Published: January 2020

Interactions between concanavalin A and cell wall digests ofBacillus subtilis168 resulted in insoluble complexes as observed by double gel diffusion, turbidity, and analysis of the precipitate. The macromolecular constituent of the cell walls complexing with concanavalin A was the polyglucosylglycerol phosphate teichoic acid. The complex exhibited twopH optima: 3.1 and 7.4. The complex could be dissociated by saccharides which bind to concanavalin A. In contrast to concanavalin A-neutral polysaccharide complexes, formation of the concanavalin A-wall complex was inhibited by salts. It was subsequently shown that salts induce conformational changes in cell wall digests. The data suggested that for complex formation to occur a rigid rod conformation in the glucosylated teichoic acid is probably necessary. Concanavalin A can be used as a probe to study structural features of bacterial cell walls.
Characterization and Regulation of Pyruvate Carboxylase of
Bacillus licheniformis
Authors: Renner E. D. , Bernlohr R. W.
Published: January 2020

Cell-free extracts of
Bacillus licheniformis
were found to contain pyruvate carboxylase which catalyzes the reaction between pyruvate and bicarbonate to yield oxalacetate in the presence of adenosine triphosphate (ATP), acetylcoenzyme A (CoA), and manganese. The plot between the reaction velocity of the carboxylation by the partially purified pyruvate carboxylase (25-fold) and the concentration of pyruvate, bicarbonate, manganese, and ATP did not indicate a pronounced deviation from the Michaelis-Menten hyperbola. The enzyme was inhibited by avidin and aspartate. Biotin partially protected the enzyme from avidin inhibition, whereas the amount of inhibition by aspartate was dependent on the concentration of acetyl-CoA present. The intracellular concentration of acetyl-CoA did not vary significantly enough to allow control of the enzyme by this method. Extracts of 4-hr postexponential-phase cells of
B. licheniformis
were also found to contain phosphoenolpyruvate carboxykinase, which appears to be under catabolite repression control. It is suggested that the endogenous induction of this enzyme is the determining factor allowing the shift to gluconeogenesis from glycolysis during sporulation of glucose-grown cells.
Ultrastructure of
Pseudomonas saccharophila
at Early and Late Log Phase of Growth
Authors: Young Ho Lee , Chao Fu-Chuan , Turnbill C. , Philpott D. E.
Published: January 2020

The fine structure of
Pseudomonas saccharophila
, a soil bacterium, is similar to that of the marine
Pseudomonas
reported by Wiebe and Chapman. The unit membrane of the plasma membrane is clearly seen in some areas of thin sections. The ribonucleoprotein granules are distributed in the cytoplasm of the cell. Cells of
P. saccharophila
during early exponential phase are large, and most of them contain a large number of poly-β-hydroxybutyrate granules. Some of the granules are quite large and occupy up to three-fourths of the cross section of the cell. Thin sections of the cells in the late log phase, however, show fewer and smaller poly-β-hydroxybutyrate granules located in the central region of the cell. Negative-stained and freeze-fracture preparations show that the outer surface of the cell wall of
P. saccharophila
is covered with a large number of tiny granules and long, slender flagella. The outer surface of the plasma membrane appears to be smoother than the outer surface of the cell wall, and it also contains numerous granules. Since the outer surface of the cell wall is quite smooth in freeze-fracture preparations, the wrinkled appearance in thin sections is probably an artifact of fixation and dehydration. The poly-β-hydroxybutyrate did not solidify at the freezing temperature used (approximately −150 C), and it was consequently pulled out in a spikelike structure during the fracturing process.
P. saccharophila
, under the conditions in our study, appears to multiply by the constrictive type of cell division.
Temperature-Sensitive Mutant of
Bacillus subtilis
That Accumulates Membrane-Associated Protein Inclusions
Authors: Behme R. J. , Fitz-James P. C.
Published: January 2020

At 47 C, a temperature-sensitive mutant of
Bacillus subtilis
168 accumulates membrane-associated protein inclusions and exhibits a pleiotropic phenotype indicative of a defect in lipid synthesis. The mutant bacteria cease growing at 47 C, and the turbidity of the culture gradually declines. The lack of growth is not due to the death or lysis of the cells, since viability does not decrease for about 1 hr and the “lysis” can be delayed for several hours by increasing the osmotic pressure of the medium. Synthesis of deoxyribonucleic acid and ribonucleic acid stops at 47 C although a residual synthesis of protein occurs. When the temperature is raised, the mutant fails to increase the proportion of 17:0 branched-chain fatty acids and to decrease the proportion of 18:0 and 18:1 fatty acids. The membrane-associated inclusions can be seen by phase-contrast or electron microscopy and remain attached to protoplast membranes during isolation. The inclusions are mostly protein and are digested with Pronase.
Factors Affecting the Level of Alanine Racemase in
Escherichia coli
Authors: Lambert Mary Pulliam , Neuhaus Francis C.
Published: January 2020

Alanine racemase occupies a key position in the alanine branch of peptidoglycan biosynthesis. The level of this enzyme in
Escherichia coli
W is a function of the carbon source. For example, growth on
l
-alanine causes a 25-fold higher level of alanine racemase when compared with growth on glucose. When potential inducers of this enzyme are added to either a glucose or succinate medium, a low specificity is observed with those compounds that cause higher levels of enzyme. Growth of
E. coli
W on either pyruvate,
d
-alanine, or
l
-alanine resulted in lower levels of
l
- and
d
-alanine in the internal pool. With each of these carbon sources, the level of alanine racemase was markedly elevated when compared to glucose-grown cells; thus, with single carbon sources, the concentration of alanine in the pool is inversely related to the specific activity of alanine racemase. These observations support derepression as a possible mechanism that gives rise to higher levels of alanine racemase. Since multiple forms of the alanine racemase were not detected in extracts from
E. coli
W grown on various carbon sources, it would appear that this type of heterogeneity is not a consideration in interpreting the above results.
Osmotic-Sensitive Mutant of
Salmonella typhimurium
Authors: Anton Dora N.
Published: January 2020

A strain (DA82) having peculiar osmotic properties was isolated in
Salmonella typhimurium
. The mutant shows increased elasticity of its cell wall and makes spherical instead of elongated cells, regardless of the osmolality of the medium. The strain withstands dilution in distilled water without disruption or death and grows normally in 0.1 molal NaCl broth (240 milliosmol), but it dies exponentially in low-osmolality broth (40 milliosmol). Addition of salts or sucrose instantly stops death and allows growth and cell division to proceed. Death is not due to lysis because this appears at later times and at a much lower rate. Osmotic inactivation is temperature-dependent: higher death rates occur at higher incubation temperatures. Inhibition of protein synthesis by chloramphenicol (20 μg/ml) prevents osmotic death. At 37 C and at lower temperatures, the phenomenon of osmotic death is transient. After a variable interval, growth of the osmotic-sensitive strain resumes. It is assumed that the strain's osmotic behavior is due to membrane defectiveness. The membrane disfunction and the wall defect shown by the strain may be consequences of a single genetic alteration or the results of independent mutations.
Cell Division of
Escherichia coli
BUG-6: Effect of Varying the Temperature Used as the Nonpermissive Growth Condition
Authors: Reeve John N. , Clark D. Joseph
Published: January 2020

When
Escherichia coli
BUG-6 is shifted from 30 C to 36 or 38 C, division does not stop, but the rate of division of the cell population is initially decreased followed by a period of increased rate of division before the rates characteristic of growth at 36 and 38 C are obtained. After a shift from 30 to 40 C, the rate of cell division gradually decreases over a 10-min period and then stops. The inhibition continues for 25 min, and then the cells divide rapidly before the division rate characteristic of 40 C is obtained. If filaments produced by 45 min of growth at 42 C are temporarily replaced at 30 C and then returned to 42 C, division occurs at 42 C. The amount of division is dependent on the length of the period at 30 C and can be decreased by a 3-min pulse of chloramphenicol immediately before the 42 to 30 C shift.
Stimulation of Unbalanced Ribonucleic Acid Synthesis in
Escherichia coli
by Methanol
Authors: Javor George T.
Published: January 2020

Addition of methanol to a stringent strain of
Escherichia coli
, starving of methionine, stimulates unbalanced ribonucleic acid (RNA) synthesis. The newly formed RNA and ribonucleoprotein species sediment between 4
S
and 30
S
. As a result of methanol treatment, cells become permeable to actinomycin D. Damage to cellular membrane appears to influence the control for RNA synthesis.
Histidine Uptake in Strains of
Neurospora crassa
with Normal and Mutant Transport Systems
Authors: Magill Clint W. , Sweeney Hugh , Woodward V. W.
Published: January 2020

Kinetic parameters for three systems of active histidine uptake by germinated conidia of
Neurospora crassa
have been measured. Each system appears to follow typical Michaelis-Menten kinetics when studied separately from the other systems. Under the conditions studied, the general amino acid transport system was found to account for the major portion of histidine uptake from low concentrations. Three types of transport mutants with altered growth inhibition patterns were selected in a histidine auxotroph. Growth of one mutant, type

bas
a

, could be inhibited by the addition of methionine to a histidine-supplemented medium, and another type,

neu
a

, could be inhibited by the addition of arginine. These mutants were shown to be lacking active histidine uptake by the basic amino acid and neutral amino acid transport systems, respectively. Another type of double mutant (

his-3, neu
r

) could be inhibited only by the addition of very high concentrations of methionine in the presence of arginine and histidine, and the mutation appeared to have altered the specificity of the neutral amino acid permease.
Mutagen Stability of Alkylation-Sensitive Mutants of
Bacillus subtilis
Authors: Hill T. , Prakash L. , Strauss B.
Published: January 2020

A series of mutations of
Bacillus subtilis
, conferring sensitivity to methyl methanesulfonate (MMS), were transferred by transformation to a suppressible
his
−
stock. The introduction of certain sensitivity mutations prevented the ultraviolet- or MMS-induced, but not the spontaneous, reversion of
his
−
to
his
+
. Not all sensitivity mutations led to this resistance to mutagenesis; a strain with altered deoxyribonucleic acid (DNA) polymerase activity behaved almost normally with respect to its mutagen response, as did an excision-defective, ultraviolet-sensitive strain used as a control. One of the mutagen-stable strains responded to mutagenesis with nitrosomethylguanidine; another appeared stable even to this mutagen. All mutagen-stable strains had DNA polymerase and DNA ligase activity.
Control of Fatty Acid Synthesis in Bacteria
Authors: Mindich Leonard
Published: January 2020

When glycerol-requiring auxotrophs of
Bacillus subtilis
are deprived of glycerol, the synthesis of fatty acids continues at an apparent rate of 20 to 50% that of supplemented cultures. The newly synthesized fatty acids are not incorporated into phospholipid and accumulate as free fatty acids. These molecules undergo a much more rapid turnover than phospholipid fatty acids, and the rate of turnover is sufficient to indicate that the rate of fatty acid synthesis in glycerol-deprived cultures is similar to that in supplemented ones. The average chain length of the free fatty acids is greater than that of the phospholipid fatty acids. Cells deprived of required amino acids also show a diminution in the apparent rate of fatty acid synthesis; however, in this case, the fatty acids accumulate in phospholipid, and no increase of the free fatty acid fraction is observed. It is argued on the basis of these findings that the control of lipid synthesis does not operate at the level of transacylation but must act on one or more of the reactions of the fatty acid synthetase.
Ribulose Diphosphate Carboxylase from Autotrophic Microorganisms
Authors: McFadden Bruce A. , Denend Anita R.
Published: January 2020

Thiobacillus denitrificans
was grown anaerobically with nitrate as an acceptor in both sterile and nonsterile media. Ribulose diphosphate carboxylase was stable throughout the exponential growth phase and declined slowly only after cells reached the stationary phase. Reversible inactivation of the carboxylase occurred in extracts as a result of bicarbonate omission. The enzyme was purified 32-fold with excellent recovery of a preparation which was 50 to 60% pure by the criterion of polyacrylamide gel electrophoresis. This purified preparation catalyzed the fixation of 1.25 μmoles of CO
2
per min per mg of protein at
p
H 8.1 and 30 C, and the molecular weight of ribulose diphosphate carboxylase was approximately 350,000 daltons. A striking biphasic time course of CO
2
fixation that was independent of protein and ribulose diphosphate concentration was observed. The optimal
p
H of the enzyme assay was fairly broad, ranging from 7 to 8.2. Kinetic dependence upon bicarbonate, ribulose diphosphate, and Mg
2+
was characterized and indicated that bicarbonate and Mg
2+
must combine with enzyme prior to addition of ribulose diphosphate. Antiserum to ribulose diphosphate carboxylase from
Hydrogenomonas eutropha
was only slightly inhibitory when added to the enzyme from
T. denitrificans
, and the mixture did not precipitate. Cyanide (4 × 10
−5
m
) gave 61% inhibition of the enzyme from
T. denitrificans
. Ribulose diphosphate carboxylase in extracts of
H. eutropha, H. facilis, Chromatium
D,
Rhodospirillum rubrum
, and
Chlorella pyrenoidosa
were also inhibited to varying extents by cyanide and antiserum to the
H. eutropha
enzyme.
Metabolism of Ethionine in Ethionine-Sensitive and Ethionine-Resistant Cells of the Enteric Yeast
Candida slooffii
Authors: Mendonça Leda C. S. , Travassos Luiz R.
Published: January 2020

In a defined medium with added ethionine plus low methionine, phenylalanine, tryptophan, tyrosine, adenine, and additional methionine reversed inhibition of the enteric yeast
Candida slooffii
by ethionine. Isoleucine and 7-methylguanine restored half-maximal growth. Choline but not triethylcholine inhibited
C. slooffii
. 6-Mercaptopurine reversed ethionine inhibition and also synergistic inhibition by ethionine plus choline. Protection against ethionine by adenine plus aromatics was also evident with log-phase cells in the absence of methionine. Incorporation of ethionine-
ethyl-1
-
14
C
by resting cells was partially inhibited by aromatic amino acids and methionine. Ethionine depressed incorporation of
3
H-phenylalanine but not of
3
H-adenine. Ethionine-resistant mutants were isolated which incorporated ethionine efficiently and degraded it to yet unidentified substances not including 5′-ethylthioadenosine. Ethionine-sensitive cells accumulated more
S
-adenosylethionine (SAE) than resistant mutants. Adenine was a good precursor of SAE. Radioactivity from ethionine-
ethyl-1
-
14
C
was recovered from cell fractions of ethionine-sensitive cells with the following distribution: cold trichloroacetic acid-soluble > hot trichloroacetic acid-insoluble > lipids > deoxyribonucleic acid > ribonucleic acid. Total radioactivity recovered from ethionine-sensitive cells was twice as much as that from ethionine-resistant mutants.
Ribonucleic Acid from Aerobically and Anaerobically Grown
Rhodopseudomonas
spheroides: Comparison by Hybridization to Chromosomal and Satellite Deoxyribonucleic Acid
Authors: Witkin Steven S. , Gibson Kenneth D.
Published: January 2020

Ribonucleic acid (RNA) species from aerobically and anaerobically grown
Rhodopseudomonas spheroides
were compared via hybridization to deoxyribonucleic acid (DNA). Both long-labeled and stable RNA bound to chromosomal DNA to the same extent, regardless of derivation. About 4% of the chromosomal DNA hybridized with total cell RNA and about 0.08% with stable RNA. About 4% of the mixed satellite DNA could be hybridized to total cell RNA from aerobic or anaerobic cultures, whereas essentially no stable RNA formed a hybrid with this DNA. Hybridization competition experiments with aerobic and anaerobic pulse-labeled RNA and chromosomal or satellite DNA demonstrated that no qualitative differences existed between the RNA species. It is concluded that identical species of RNA in the same relative amounts are synthesized by
R. spheroides
during aerobic or anaerobic growth on the same medium.
Induction and Characterization of β-Galactosidase in an Extreme Thermophile
Authors: Ulrich J. T. , McFeters G. A. , Temple K. L.
Published: January 2020

A thermostable β-galactosidase (EC 3.2.1.23; β-
d
galactoside galactohydrolase) was found to be inducible in an extreme thermophile resembling
Thermus aquaticus
. Enzyme induction was achieved by the addition of lactose, galactose, or the α-galactoside, melibiose, to growing cultures. The addition of glucose to induced cultures had a repressive effect on further enzyme synthesis. The enzyme was purified 78-fold, and the optimum temperature and
p
H for activity were determined to be 80 C and
p
H 5.0, respectively. The enzyme was activated by both manganese and ferrous iron. Sulfhydryl activation and thermal stabilization indicate that the thermophilic β-galactosidase is a sulfhydryl enzyme. Kinetic determinations at 80 C established a
K
m
of 2.0 × 10
−3
m
for the chromogenic substrate
o
-nitrophenyl β-
d
-galactopyranoside (ONPG) and a
K
1
of 7.5 × 10
−3
m
for lactose. The Arrhenius energy of activation (for the hydrolysis of ONPG) was calculated to be 13.7 kcal/mole. A molecular weight of 5.7 × 10
5
daltons was estimated by elution of the enzyme from Sephadex 4B.
Isolation of Mycoplasma Membranes by Digitonin
Authors: Rottem Shlomo , Razin Shmuel
Published: January 2020

The cell membrane of
Mycoplasma hominis
was isolated by lysing the cells with digitonin. Electron microscopy and chemical, density gradient, and electrophoretic analyses of the membrane proteins showed the membranes so obtained, like those isolated by osmotic lysis, to be relatively free of cytoplasmic contaminants. Sensitivity to digitonin lysis depended on temperature but was not affected by Mg
2+
ions and was only slightly affected by the age of the culture. Accordingly, it seems that digitonin may be used for the isolation of cell membranes from sterol-requiring mycoplasmas that tend to be fairly resistant to osmotic lysis.
Novel Anaerobic Cellulolytic Bacterium
Authors: Leatherwood J. M. , Sharma M. P.
Published: January 2020

A morphologically novel bacterium which ferments cellulose and produces butyric acid was isolated from a bovine rumen. It grows in long twisted chains that often form a double-helical pattern.
sai-1
Mutation in
Saccharomyces cerevisiae
: Characteristics of Inhibition by
S
-Adenosylmethionine and
S
-Adenosylhomocysteine and Protection by Methionine
Authors: Spence Kemet D. , Shapiro Stanley K. , Hutson Nancy K.
Published: January 2020

The relationship of methionine to the inhibition caused by
S
-adenosylmethionine and
S
-adenosylhomocysteine in strains containing the
sai-1
mutation has been investigated and shown to affect indirectly the survival of the mutants. The ability of the mutants to take up both inhibitors is similar to that of the wild-type cells. The mutant also retains the ability to hydrolyze
S
-adenosylhomocysteine and incorporate the hydrolytic products into the various cellular fractions. Maximal inhibition of the
sai-1
mutants occurs at an extracellular concentration of 0.005 m
m
S
-adenosylmethionine and 0.025 to 0.05 m
m
S
-adenosylhomocysteine when the cellular concentration is 0.05 mg (dry weight) per ml. The results suggest that the
sai-1
mutation affects reaction(s) either not associated with methionine biosynthesis, or methionine synthesis and at least one other critical cellular function.
Isolation and Characterization of Ultraviolet Light-Sensitive Mutants of the Blue-Green Alga
Anacystis nidulans
Authors: Asato Yukio
Published: January 2020

Three independently isolated ultraviolet light-sensitive (uvs) mutants of
Anacystis nidulans
were characterized. Strain uvs-1 was most sensitive to UV in the absence of photoreactivation. Pretreatment with caffeine suppressed the dark-survival curve of strain uvs-1, indicating the presence of excision enzymes involved in dark repair. Under “black” and “white” illumination, strain uvs-1 displays photoreactivation properties nearly comparable to wild-type culture. Mutants uvs-35 and uvs-88 appeared to have partial photorecovery capacities. Upon pretreatment with chloramphenicol, photoreactivation properties of strains uvs-1 and uvs-88 were not evident although the partial photoreactivation characteristics of strain uvs-35 remained the same. Data indicate that strains uvs-1, uvs-35, and uvs-88 are probably genetically distinct UV-sensitive mutants.
Conjugational Complementation Analysis of Transfer-Deficient Mutants of F
lac
in
Escherichia coli
Authors: Achtman Mark , Willetts Neil , Clark Alvin J.
Published: January 2020

A series of 102 transfer-deficient (
tra
−
) mutants of F
lac
(84 of which have been previously described) were classified as carrying frameshift, amber, ochre, UGA, and nonsuppressible mutations. Techniques were evolved for using cultures of F prime strains as efficient recipients in matings, for measuring the number of (F′/F′) heterozygote cells in transient populations, and for measuring complementation between different F
lac tra
−
mutants. These techniques were used to define nine
tra
cistrons and to assign most of the
tra
−
mutations to one or other of these.
Dependence of Cell Division on the Completion of Chromosome Replication in
Caulobacter crescentus
Authors: Degnen Suzanne T. , Newton Austin
Published: January 2020

The relationship between chromosome replication and cell division in the stalked bacterium
Caulobacter crescentus
has been investigated. Two compounds, hydroxyurea and mitomycin C, were found to inhibit completely deoxyribonucleic acid (DNA) synthesis while allowing continued cell growth and elongation. When these inhibitors were added to exponentially growing cultures, cell division stopped after 38 min when hydroxyurea was used and after 33 min when mitomycin C was used. The period of continued cell division corresponds closely to the period previously determined for the postsynthetic gap (G2) in the DNA cycle of this organism. These results indicate that cell division is coupled to the completion of chromosome replication in
C. crescentus
.
Determination of the Rate of Transformation from Growth Curves of Transformed Streptococci
Authors: Schlegel Richard , Slade Hutton D.
Published: January 2020

A rapid method of determining the rate of transformation of group H streptococci to streptomycin resistance has been developed. The new technique, which involves analysis of the growth response of transformed streptococci in liquid medium containing streptomycin, is independent of chain length fluctuations and is demonstrably more accurate than the standard plating method. The relatively short generation time of streptococci under these conditions permits transformation rates to be estimated in 9 to 14 hr depending on the number of transformants in the inocula as compared to 50 hr by the agar plate procedure.
Effect of Peptone on
Azotobacter
Morphology
Authors: Vela G. R. , Rosenthal R. S.
Published: January 2020

Pleomorphism in cultures of
Azotobacter vinelandii
was induced by addition of Difco peptone to the growth medium. Under the conditions of the study, 5% peptone gave rise to transient forms described as “fungoid cells” which were osmotically fragile. After some 48 hr of culture, they became osmotically stable and resumed a more typical morphology. It was shown that the pleomorphism-inducing principle in peptone was glycine.
Orientation of the
deo
Genes and the
serB
Locus in
Salmonella typhimurium
Authors: Jargiello Patricia , Hoffee Patricia
Published: January 2020

In
Salmonella typhimurium
, the order of the
deo
genes with respect to the
serB
locus has been determined as
deoC-deoA-deoB-deoD-serB-thr
.
Enzymes of the Isoleucine-Valine Pathway in
Acinetobacter
Authors: Twarog Robert
Published: January 2020

Regulation of four of the enzymes required for isoleucine and valine biosynthesis in
Acinetobacter
was studied. A three- to fourfold derepression of acetohydroxyacid synthetase was routinely observed in two different wild-type strains when grown in minimal medium relative to cells grown in minimal medium supplemented with leucine, valine, and isoleucine. A similar degree of synthetase derepression was observed in appropriately grown isoleucine or leucine auxotrophs. No significant derepression of threonine deaminase or transaminase B occurred in either wild-type or mutant cells grown under a variety of conditions. Three amino acid analogues were tested with wild-type cells; except for a two- to threefold derepression of dihydroxyacid dehydrase when high concentrations of aminobutyric acid were added to the medium, essentially the same results were obtained. Experiments showed that threonine deaminase is subject to feedback inhibition by isoleucine and that valine reverses this inhibition. Cooperative effects in threonine deaminase were demonstrated with crude extracts. The data indicate that the synthesis of isoleucine and valine in
Acinetobacter
is regulated by repression control of acetohydroxyacid synthetase and feedback inhibition of threonine deaminase and acetohydroxyacid synthetase.
Transition of Chemolithotroph
Ferrobacillus ferrooxidans
to Obligate Organotrophy and Metabolic Capabilities of Glucose-Grown Cells
Authors: Shafia Fred , Brinson Karen R. , Heinzman Michael W. , Brady James M.
Published: January 2020

Transition of chemolithotrophic
Ferrobacillus ferrooxidans
to organotrophy occurred after 60 hr of incubation in an organic medium. Three distinct phases, based on metabolic activities of cells, were observed during the course of transition. Conversion of cellular nutrition to organotrophy resulted in a gradual loss of Fe
2+
oxidation and cessation of CO
2
fixation. These changes were concomitant with a rapid increase in uptake of glucose and phosphate during the latter part of transition period. The outcome of transition was governed by the
p
H of the medium, temperature of incubation, availability of oxygen, age of the chemolithotrophic cells, and the type of energy and carbon source available to the bacterium. Presence or absence of
p
-aminobenzoic acid and Fe
2+
ions did not influence transition of cells. A defined medium containing glucose, mineral salts, and
p
-aminobenzoic acid at
p
H 2.5 was found to be most suitable for transition and for culture of heterotrophic convertants. Maximum growth rate of the heterotrophic cells was attained with vigorous aeration at 35 C. The bacterium could be cultured on a variety of organic compounds, including complex organic media, provided they were used in low concentrations. Serological studies on autotrophic cells and the heterotrophic convertant have shown a definite antigenic relationship between the two cell types.
Loss of R Factors Promoted by Bacteriophage M13 and the M13 Carrier State
Authors: Russell S. E. , Iyer V. N.
Published: January 2020

The infection of different Hfr strains ofEscherichia colibearing derepressed R factors of the fi+or fi−type can result in the loss of the R factor and the conversion of the infected cells to the R−state. This extends earlier observations on the elimination of F′ factors by bacteriophage M13 infection. Variability in the efficiency of this conversion can arise because of genetic factors independent of the R factor being eliminated. A fraction of the infected but unconverted R+cells were M13 carrier strains. The carrier state had an intracellular basis, and single R+cells could maintain the carrier state.
Vibrio psychroerythrus
sp. n.: Classification of the Psychrophilic Marine Bacterium, NRC 1004
Authors: D'aoust J. Y. , Kushner D. J.
Published: January 2020

A red-pigmented organism, formerly known as marine psychrophile NRC 1004, has been classified as
Vibrio psychroerythrus
sp. n. Classification was mainly based on morphology, the ability of the organism to oxidize and ferment glucose, its sensitivity to vibriostat 0/129, and its deoxyribonucleic acid base composition of 40.0 moles% guanine plus cytosine, determined by thermal denaturation. The organism gave positive reactions for catalase, oxidase, and starch hydrolysis and produced acid from maltose and dextrin but not from arabinose. It was indole- and citrate-negative and reduced nitrate to nitrite without producing gas.
Location of
trpR
Mutations in the
serB-thr
Region of
Salmonella typhimurium
Authors: Stuttard C.
Published: January 2020

Tryptophan biosynthesis in
Salmonella
is controlled by at least one regulatory gene,
trpR
, which is cotransducible with
thr
genes and not with the
trp
operon. Mutations in
trpR
cause derepression of tryptophan enzyme synthesis and confer resistance to growth inhibition by 5-methyltryptophan. Nineteen
trpR
mutations were mapped with respect to
thrA
and
serB
markers by two-point (ratio) and three-point transduction tests. The results are all consistent with the site order
serB80-trpR-thrA59
on the
Salmonella
chromosome. Very low or undetectable levels of recombination between different
trpR
mutations have so far prevented the determination of fine structure in the
trpR
gene. Thirteen other 5-methyltryptophan-resistant mutants previously found not to be cotransducible with either the
trp
operon or
thrA
, and designated
trpT
, were also used in these experiments. Lack of cotransducibility with
thrA
was confirmed, and no linkage with
serB
was detected. The nature and location of
trpT
mutations remain obscure.
Inhibition by 2-Deoxy-
d
-Glucose of Synthesis of Glycoprotein Enzymes by Protoplasts of
Saccharomyces
: Relation to Inhibition of Sugar Uptake and Metabolism
Authors: Kuo S.-C. , Lampen J. O.
Published: January 2020

The synthesis of the glycoprotein enzymes, invertase and acid phosphatase, by protoplasts of
Saccharomyces
mutant 1016, is inhibited by 2-deoxy-
d
-glucose (2-dG) after a 20- to 30-min lag period under conditions (external sugar to 2-dG ratio of 40:1) which cause only a slight decrease in total protein synthesis. Formation of one intracellular enzyme, alpha-glucosidase, is also sensitive, but production of another, alkaline phosphatase, is unaffected. A nonmetabolized glucose analogue, 6-deoxy-
d
-glucose, had no inhibitory effect. The total uptake of external fructose and maltose was decreased by 2-dG after a lag period of about the same duration as that before the inhibition of synthesis of enzymes or of mannan and glucan; during this time 2-dG was taken up by the protoplasts and accumulated primarily as 2-dG-6-phosphate (2-dG-6-P). Studies in vitro showed that 2-dG-6-P inhibits both yeast phosphoglucose isomerase and phosphomannose isomerase. The intracellular levels of the 6-phosphates of glucose, fructose, and mannose did not increase in the presence of 2-dG. We suggest that the high internal level of 2-dG-6-P blocks synthesis of the cell wall polysaccharides and glycoproteins in two ways. It directly inhibits the conversion of fructose-6-P to glucose-6-P and to mannose-6-P. At the same time, it restricts the transport of fructose and maltose into the cell; however, the continuing limited uptake of the sugars still provides sufficient energy for protein synthesis. The cessation of alpha-glucosidase synthesis is probably a result of depletion of the internal pool of maltose (the inducer). Our findings support the suggestion that restriction of synthesis of the carbohydrate moiety of glycoproteins reduces formation of the active enzyme.
Evidence for a Phosphoenolpyruvate-Dependent Sugar Phosphotransferase in
Mycoplasma
Strain Y
Authors: Van Demark P. J. , Plackett P.
Published: January 2020

The uptake of
14
C-α-methyl-
d
-glucoside (αMG) by washed cells of
Mycoplasma
strain Y was found to be dependent on the supply of metabolic energy. Glycerol or
d
-mannose, but not
l
-lactate, would serve as an energy source. Uptake was inhibited by fluoride, iodoacetate, and arsenate, but not by 2,4-dinitrophenol.
d
-Glucose was inhibitory, presumably by competing for the transport system. The initial product of accumulation had the properties of a phosphate ester of αMG. The proportion of free αMG in the cells increased with time, until a steady state was reached in which uptake was balanced by the efflux of free αMG from the cells. Broken-cell preparations catalyzed a phosphoenolpyruvate-dependent phosphorylation of αMG and of
d
-glucose.
Effect of Cyclopentaneglycine on Metabolism in
Salmonella typhimurium
Authors: O'neill J. Patrick , Freundlich Martin
Published: January 2020

Cyclopentaneglycine (CPG) inhibited the growth of wild-type
Salmonella typhimurium
. The inhibition was overcome by isoleucine or any isoleucine precursor formed after threonine. CPG appeared to mimic isoleucine as a strong inhibitor of the activity of
l
-threonine deaminase. The analogue was a poor inhibitor of isoleucyl-transfer ribonucleic acid synthetase. CPG did not appear to be incorporated into protein nor did it replace isoleucine in repression. Cells that had recovered from growth inhibition by CPG had derepressed levels of the isoleucine-valine biosynthetic enzymes.
Aminotransferase from a Deletion Mutant in the Histidine Operon
Authors: Albritton W. L. , Levin Alfred P.
Published: January 2020

The imidazolylacetolphosphate:
l
-glutamate aminotransferase from the deletion mutant
hisHB22
has been partially characterized. Although genetic studies have not yet shown the deletion to involve the structural information for this enzyme, physical studies indicate that an abnormal enzyme is produced. Evidence is presented which, together with previous data on the characterization of the enzyme, indicates that the catalytic integrity of the enzyme is intact, and that the low specific activity seen in cell extracts is due to formation of an enzyme which has a reduced coenzyme content. It is suggested that this reduced coenzyme content is due primarily to a reduced affinity of the enzyme (nascent or apo-) for its coenzyme, and that the coenzyme must be incorporated into the enzyme at the moment of synthesis for formation of a functional protein.
Cell Division Mutations in the Blue-Green Bacterium
Agmenellum quadruplicatum
Strain BG1: a Comparison of the Cell Wall
Authors: Ingram L. O. , Van Baalen C. , Fisher W. D.
Published: January 2020

The peptidoglycan from two types of filamentous cell division mutants of
Agmenellum quadruplicatum
strain BG1 has been compared to that of the parent organism. Small variations in the total peptidoglycan composition on a dry-weight basis were found in the mutants. The reduced level of peptidoglycan in the serpentine mutant is consistent with a general decrease in the ratio of surface area to volume as compared to the parent organism. The increased peptidoglycan content in the septate mutant confirms previous ultrastructural observations of the greatly enlarged peptidoglycan septum between adjacent cells. A comparison of peptidoglycan composition and cross-linking in the two types of filamentous mutants of
A. quadruplicatum
and in drug-induced phenocopies suggests that structural alterations of the peptidoglycan are not involved in the apparent impairments of cellular division. Furthermore, data concerning the relative susceptibilities of the parent and mutants to antibiotics indicate that neither mutant exhibits a gross alteration of permeability.
Occurrence and Properties of Lactic Dehydrogenases of Fermentative Mycoplasmas
Authors: Neimark Harold , Lemcke Ruth M.
Published: January 2020

Eight fermentative mycoplasmas differing in genome size, deoxyribonucleic acid (DNA) base composition, or sterol dependence were examined for lactic dehydrogenase composition by spectrophotometric assay and polyacrylamide gel electrophoresis. Three completely different patterns of lactic dehydrogenase composition were found. (i) A nicotinamide adenine dinucleotide (NAD)-dependentl(+)-lactic dehydrogenase was found inMycoplasma pneumoniae, M. gallisepticum, M. mycoidesvar.mycoides, mycoplasma UM 30847,M. neurolyticum, andAcholeplasma axanthum. Electrophoresis of cell-free extracts of each of these mycoplasmas produced, with the exception ofM. mycoidesvar.mycoidesand UM 30847, single, different enzyme bands.M. mycoidesvar.mycoidesand UM 30847 were similar and formed multiple bands of enzyme activity. We were unable to establish whether these multiple bands were due to lactic dehydrogenase isoenzymes or artifacts. (ii) An NAD-dependentd(−)-lactic dehydrogenase which could not be reversed to oxidize lactate was found inM. fermentans. (iii)A. laidlawiiA possessed an NAD-independentd(−)-lactic dehydrogenase capable of reducing dichlorophenol-indophenol, and an NAD-dependentl(+)-lactic dehydrogenase which is specifically activated by fructose-1,6-diphosphate. Heretofore, this enzyme regulatory mechanism was known to occur only among theLactobacillaceae. No yeast-type lactic dehydrogenase activity was found in any of the mycoplasmas examined. The stereoisomer of lactic acid accumulated during growth correlated perfectly with the type of NAD-dependent lactic dehydrogenase found in each mycoplasma. The types of lactic dehydrogenase activity found in these mycoplasmas were not related to genome size, DNA base composition, or sterol dependence.
Effect of Thymine Limitation on Chromosomal Deoxyribonucleic Acid Synthesis in
Proteus mirabilis
Authors: Barnes Marjorie H. , Rownd R.
Published: January 2020

The effects of thymine limitation on the rates of growth, deoxyribonucleic acid (DNA) synthesis, and increase in viable cell number for a thymine auxotroph of
Proteus mirabilis
were investigated. At thymine concentrations of 1.0 μg/ml and below, these rates were markedly decreased. After a reduction in thymine concentration from 10 μg/ml to 0.2 μg/ml, mass synthesis continued at the preshift rate for several hours. In contrast, the rate of DNA synthesis immediately decreased, resulting in a decrease in the DNA to mass ratio to about one-half of its normal level. Viable counts remained constant for several hours after the reduction in thymine concentration, and enlarged cells and multicellular “snakes” were formed. The rate of DNA synthesis was reduced at thymine concentrations below approximately 1.7 μg/ml. The addition of thymine to cultures which had been completely starved for thymine increased the rate of DNA synthesis to at least twice its normal value; this suggests that extra rounds of chromosome replication can be induced in
P. mirabilis
as previously observed in
Escherichia coli
.
Ribonuclease II Activity in a “Presumptive” Ribonuclease II-Deficient Mutant
Authors: Weatherford Stephen C. , Wright Michel , Apirion David
Published: January 2020

A mutant strain of
Escherichia coli
previously thought to possess low levels of ribonuclease II activity has normal levels of ribonuclease II after partial purification of this enzyme from crude extracts.
Escherichia coli
Mutants that Require Either Pyridoxine or Alanine
Authors: Dempsey Valter B.
Published: January 2020

Some pyridoxineless mutants of genetic group V grow to normal cell yields in glucose-salts medium containing 0.11 m
m d
- or
l
-alanine as the sole supplement.
Molecular Weight of Deoxyribonucleic Acid Synthesized During Initiation of Chromosome Replication in
Escherichia coli
Authors: Kuempel Peter L.
Published: January 2020

Alkaline sucrose gradients were used to study the molecular weight of deoxyribonucleic acid (DNA) synthesized during the initiation of chromosome replication in
Escherichia coli
15 TAU-bar. The experiments were conducted to determine whether newly synthesized, replication origin DNA is attached to higher-molecular-weight parental DNA. Little of the DNA synthesized after readdition of required amino acids to cells previously deprived of the amino acids was present in DNA with a molecular weight comparable to that of the parental DNA. The newly synthesized, low-molecular-weight DNA rapidly appeared in higher-molecular-weight material, but there was an upper limit to the size of this intermediate-molecular-weight DNA. This limit was not observed when exponentially growing cells converted newly synthesized DNA to higher-molecular-weight material. The size of the intermediate-molecular-weight DNA was related to the age of the replication forks, and the size increased as the replication forks moved further from the replication origin. The results indicate that the newly synthesized replication origin DNA is not attached to parental DNA, but it is rapidly attached to the growing strands that extend from the replication fork to the replication origin, or to the other replication fork if replication is bidirectional. Experiments are reported which demonstrate that the DNA investigated was from the vicinity of the replication origin and was not plasmid DNA or DNA from random positions on the chromosome.
Evidence for Specific Inhibition of Translocation of Aminoacyl-Transfer Ribonucleic Acid by the Pretreatment of Ribosomes of
Bacillus subtilis
with
p
-Chloromercuribenzoate
Authors: Ranu Rajinder Singh , Kaji Akira
Published: January 2020

The biological activities of
Bacillus subtilis
ribosomes pretreated with 0.5, 1, or 2 m
m
p
-chloromercuribenzoate (PCMB) were examined. The ribosomes treated with 1 or 2 m
m
PCMB lost their capacity to synthesize polyphenylalanine as well as the capacity to bind phenylalanyl-transfer ribonucleic acid. On the other hand, approximately 70% of the polyphenylalanine synthesis capacity was lost with ribosomes pretreated with 0.5 m
m
PCMB. This inhibition was found to be due to a specific inhibition of the translocation step. The effect of 0.5 m
m
PCMB was reversed by 20 m
m
Mg
2+
without the loss of PCMB bound to ribosomes, while β-mercaptoethanol partially reversed the inhibitory effect with concomitant loss of bound PCMB.
Mapping of the
fabA
Locus for Unsaturated Fatty Acid Biosynthesis in
Escherichia coli
Authors: Cronan John E. , Silbert David F. , Wulff Daniel L.
Published: January 2020

fabA
mutants of
Escherichia coli
require an appropriate unsaturated fatty acid for growth. The
fabA
locus has now been mapped at minute 21.5 of the linkage map of
E. coli
. The locus is cotransduced with
pyrD
and
aroA
but not with
pyrC, purB
, or
pdxC
. The clockwise order of markers in the region is
pdxC, aroA, cmlB, pyrD, fabA, pyrC
.
Specificity, Induction, and Absorption of Pesticin
Authors: Hu P. C. , Yang G. C. H. , Brubaker R. R.
Published: January 2020

Irradiation of pesticinogenic (Pst+) cells ofYersinia pestiswith ultraviolet light resulted in a five- to eightfold increase in titer of intracellular pesticin. Extracellular activity in irradiated or control cultures never approached that found within the bacteria. Upon chromatography of crude extracts of Pst+cells on columns of diethylaminoethyl-cellulose, Sephadex G200, and calcium hydroxyapatite, fractions were recovered which inhibited the growth of indicator cells ofEscherichia coli, Y. pseudotuberculosis, Y. enterocolitica, and Pst−Y. pestis. By means of these methods, in conjuntion with fractional precipitation with ammonium sulfate, the antibacterial activity was purified to homogeneity (as judged by disc gel electrophoresis and analysis by double diffusion in agar). The relative sensitivity of each cell type was constant and not affected by the state of purification. These findings indicate that the pesticin molecule alone accounts for lethality. Cells ofE. coliandY. pseudotuberculosiswere about 100 and 10 times more sensitive to pesticin, respectively, than were those of Pst−Y. pestis. Activity directed against sensitive cells of these three species was enhanced by 0.1% ethylenediaminetetraacetate (EDTA) and completely inhibited by 0.01mhemin or 0.001mFe3+. The response ofY. enterocoliticato pesticin was variable in the presence of EDTA and was not influenced by Fe3+. Attempts to detect common surface structures responsible for absorption of pesticin by the four cell types were not successful.