bluuebunny/crossref_metadata_2025 huggingface dataset:
Postreplication Repair of Ultraviolet Damage in
Haemophilus influenzae
Authors: Leclerc J. Eugene , Setlow Jane K.
Published: January 2020

The deoxyribonucleic acid (DNA) synthesized following ultraviolet (UV) irradiation of wild-type (Rd) and recombination-defective strains of
Haemophilus influenzae
has been analyzed by alkaline sucrose gradient sedimentation. Strain Rd and a UV-resistant, recombination-defective strain Rd(DB117)
rec−
are able to carry out postreplication repair, i.e., close the single-strand gaps in the newly synthesized DNA; in the UV-sensitive, recombination-defective strain DB117, the gaps remain open. The lack of postreplication repair in this strain may be the result of degradation of the newly synthesized DNA.
Heterotrophic Nitrification by
Arthrobacter
sp
Authors: Verstraete W. , Alexander M.
Published: January 2020

Arthrobacter
sp. isolated from sewage oxidized ammonium to hydroxylamine, a bound hydroxylamine compound, a hydroxamic acid, a substance presumed to be a primary nitro compound, nitrite, and nitrate. The concentration of free hydroxylamine-nitrogen reached 15 μg/ml. The identification of hydroxylamine was verified by mass spectrometric analysis of its benzophenone oxime derivative. The bound hydroxylamine was tentatively identified as 1-nitrosoethanol on the basis of its mass spectrum, chemical reactions, and infrared and ultraviolet spectra. Hydroxylamine formation by growing cells was relatively independent of
p
H, but the accumulation of nitrite was strongly favored in alkaline solutions. The formation of hydroxylamine but not nitrite was regulated by the carbon to nitrogen ratio of the medium. The hydroxamic acid was the dominant product of nitrification in iron-deficient media, but hydroxylamine, nitrite, and 1-nitrosoethanol formation was favored in iron-rich solutions. Heterotrophic nitrification by
Arthrobacter
sp. was not inhibited by several compounds at concentrations which totally inhibited autotrophic nitrification.
Genetically Controlled Removal of “Spore Photoproduct” from Deoxyribonucleic Acid of Ultraviolet-Irradiated
Bacillus subtilis
Spores
Authors: Munakata Nobuo , Rupert Claud S.
Published: January 2020

Previous genetic analysis indicated that at least two genes determine the ultraviolet (UV) sensitivity of
Bacillus subtilis
spores. The present study shows that these genes independently control two distinguishable processes for removing UV-induced spore photoproduct (5-thyminyl-5,6-dihydrothymine, or TDHT) from spore deoxyribonucleic acid. The first, is a spore repair mechanism by which TDHT is removed rapidly without appearing in acid-soluble form. This mechanism, which is demonstrated in both UV-resistant and excision-deficient strains, operates to a certain extent during germination without requiring vegetative growth. The second, demonstrated in a mutant which lacks the first mechanism, removes TDHT relatively slowly and only if germinated spores are allowed to develop toward vegetative cells. The latter mechanism appears identical to excision-resynthesis repair, since the mutation abolishing it renders the irradiated vegetative cells incapable of removing cyclobutane-type pyrimidine dimers. Blocking either one of these mechanisms only slightly affects the UV sensitivity of spores, but blocking both prevents TDHT removal and gives high UV sensitivity.
Synthesis of Pulcherriminic Acid by
Bacillus subtilis
Authors: Uffen Robert L. , Canale-Parola E.
Published: January 2020

The pathway of pulcherriminic acid synthesis in
Bacillus subtilis
strains AM and AM-L11 (a leucine-requiring auxotroph) was investigated. Determinations of radioactivity in pulcherriminic acid synthesized by cells growing in media containing
14
C-labeled amino acids indicated that
B. subtilis
produced pulcherriminic acid from
l
-leucine. The organism utilized the carbon skeletons of two
l
-leucine molecules to synthesize one molecule of pulcherriminic acid. Similar results were obtained with starved cell suspensions. Growing cells formed significant amounts of pulcherriminic acid only in media including a carbohydrate such as starch. However, carbohydrate carbon was not required for the synthesis of pulcherriminic acid molecules. Data obtained with cell suspensions supported the hypothesis that cyclo-
l
-leucyl-
l
-leucyl is an intermediate in pulcherriminic acid biosynthesis and indicated that molecular oxygen is required for the conversion of cyclo-
l
-leucyl-
l
-leucyl to pulcherriminic acid. A pathway for the synthesis of pulcherrimin from
l
-leucine in
B. subtilis
is proposed.
Isotopic Study of Control of the Lysine Biosynthetic Pathway During Sporulation of
Bacillus cereus
Authors: Rogers S. W. , Peterson D. E. , Bernlohr R. W. , Stahly D. P.
Published: January 2020

The extent of incorporation of aspartate into dipicolinic acid and into various amino compounds was determined in
Bacillus cereus
at various times before, during, and near the end of synthesis of dipicolinic acid. The purpose of this study was to gain further information on the in vivo control of the biosynthesis of amino acids derived from aspartate. Control of the lysine biosynthetic pathway was of particular interest with regard to sporulation, owing to the important role of diaminopimelate and dipicolinate in the structure of the spore. As synthesis of dipicolinate was initiated, incorporation of carbon derived from aspartate was funneled preferentially into this compound as compared with others of the aspartate group. Incorporation into lysine essentially stopped just before the synthesis of dipicolinate began. This is consistent with the previously observed disappearance at this time of diaminopimelic acid decarboxylase in cell-free extracts. Synthesis of diaminopimelate continued during the time of synthesis of dipicolinate. The previous suggestion that diaminopimelate might exert negative control on one of the enzymes between dihydrodipicolinate and diaminopimelate is thus considered unlikely. The possibility is discussed that synthesis of dipicolinate is favored by an increase in the rate of synthesis of dihydrodipicolinate rather than by a block in its rate of utilization.
Induction of Galactokinase in
Saccharomyces cerevisiae
: Kinetics of Induction and Glucose Effects
Authors: Adams Bruce G.
Published: January 2020

The induced synthesis of galactokinase and the repressing effects of glucose on this synthesis have been investigated in whole yeast cells rendered permeable by treatment with dimethyl sulfoxide. It was found that the induction response of uninduced cells to galactose is clearly dependent on the nature of the carbon source upon which the culture was grown prior to exposure to galactose. Glucose-grown cells exhibited a long lag before induction, whereas lactate-grown cells exhibited induced synthesis within 8 min. A concentration of 0.5% galactose was found to be optimal for induction. The addition of glucose to yeast cultures growing on galactose resulted in a severe transient repression of synthesis which was followed by a resumed rate of synthesis characteristic of a weaker permanent catabolite repression. Neither 2-deoxygalactose nor fucose acted as gratuitous inducers of the pathway, nor did they serve as a substrates for galactokinase.
Factors Affecting Hexose Phosphorylation in
Acetobacter xylinum
Authors: Benziman Moshe , Rivetz B.
Published: January 2020

Fructose was oxidized and converted to cellulose by cells of
Acetobacter xylinum
grown on fructose or succinate, but not by cells grown on glucose. In resting fructose-grown cells, glucose strongly suppressed fructose utilization. Extracts obtained from fructose- or succinate-grown cells catalyzed the adenosine triphosphate (ATP)-dependent formation of the 6-phosphate esters of glucose and fructose, whereas glucose-grown cell extracts phosphorylated glucose but not fructose. Fructokinase and glucokinase activities were separated and partially purified from cells grown on glucose, fructose, or succinate. Whereas fructokinase phosphorylated fructose only, glucokinase was active towards glucose and less active towards mannose and glucosamine. The optimal
p
H for the fructokinase was 7.4 and for the glucokinase was 8.5. The
K
m
values for the fructokinase were: fructose, 6.2 m
m
; and ATP, 0.83 m
m
. The
K
m
values for the glucokinase were: glucose, 0.22 m
m
; and ATP, 4.2 m
m
. Fructokinase was inhibited by glucose, glucosamine, mannose, and deoxyglucose in a manner competitive with respect to fructose, with
K
i
values of 0.1, 0.14, 0.5, and 7.5 m
m
, respectively. Adenosine diphosphate (ADP) and adenosine monophosphate (AMP) inhibited both kinases noncompetitively with respect to ATP. The
K
i
values were: 1.8 m
m
(ADP) and 2.1 m
m
(AMP) for fructokinase, and 2.2 m
m
(ADP) and 9.6 m
m
(AMP) for glucokinase. Fructose metabolism in
A. xylinum
appears to be regulated by the synthesis and activity of fructokinase.
Effects of Fatty Acids on Growth and Envelope Proteins of
Bacillus subtilis
Authors: Sheu Chingju W. , Freese Ernst
Published: January 2020

Fatty acids of different chain lengths were added to cultures of
Bacillus subtilis
growing in nutrient sporulation medium, and the effects of these fatty acids on growth, oxygen uptake, adenosine triphosphate (ATP) concentration, and membrane protein composition were examined. All fatty acids inhibited growth, the effect being reduced in the presence of glycolytic compounds and reversed by transfer to medium without fatty acids. The inhibition of growth was correlated with a reduction in both the rate of oxygen consumption and the concentration of ATP per cell. The concentration required to obtain a certain degree of inhibition increased with decreasing molecular weight of the fatty acid. However, the reduced nicotinamide adenine dinucleotide oxidation system of cell envelope preparations (i.e., the electron transport system) was not inhibited. Submaximal growth inhibition was accompanied by the relative increase of a membrane protein band revealed by urea-acetic acid gel electrophoresis. This increase was blocked by actinomycin or chloramphenicol. All of the above changes could also be produced by 2,4-dinitrophenol. The inhibition results are best explained by assuming that the fatty acids reversibly react with the cell membrane or proteins in it; they could either alter the membrane structure or uncouple the electron transport chain from two types of proteins, those used for ATP regeneration and others needed for the transport of certain compounds into the cells.
Appearance of Muramic Lactam During Cortex Synthesis in Sporulating Cultures of
Bacillus cereus
and
Bacillus megaterium
Authors: Wickus Gary G. , Warth Alan D. , Strominger Jack L.
Published: January 2020

Evidence is presented for the appearance of muramic lactam during the late stages of sporulation at about the same time dipicolinic acid synthesis occurs.
Effects of Treatment with Sodium Dodecyl Sulfate on the Ultrastructure of
Escherichia coli
Authors: Woldringh C. L. , Van Iterson Woutera
Published: January 2020

An electron microscopy study has been made of the effects of dissolution of the plasma membrane of
Escherichia coli
with sodium dodecyl sulfate (SDS) on the organization of the nucleoplasm and the cytoplasm. The alterations observed in time course experiments were related to absorbance changes and to release of macromolecules from the cells. As the cells became plasmolyzed, under the conditions used, the first visible effect of SDS was a collapse of the plasmolysis spaces. This was accompanied by a displacement of the nuclear material which then appeared in broad contact with the redeployed plasma membrane. This initial displacement of nuclear material to the cell border may indicate an association between the nucleoplasm and the plasma membrane. Upon further dissolution of the plasma membrane, the nuclear material receded from the cell margin and contracted into an axial filament. Meanwhile, the cytoplasm dissociated into an amorphous, Pronase-sensitive component and an electron-opaque, granular one sensitive to ribonuclease. The latter represented one continuous area of ribosomal structures surrounding the nucleoplasm, an organization which did not occur when the cells were inhibited with rifamycin before SDS treatment. During prolonged SDS interaction, approximately 65% of the cellular protein, 25% of the ribonucleic acid and 40% of the deoxyribonucleic acid were released from the cells concomitant with the disappearance of the amorphous cytoplasmic part, expansion of the ribosomal aggregate, and rearrangement of the nuclear material at the cell periphery. The observations support the contention that all ribosomal structures bear a direct relationship with the nucleoplasm.
Effects of Colicins E1 and K on Permeability to Magnesium and Cobaltous Ions
Authors: Lusk Joan E. , Nelson David L.
Published: January 2020

The energy-dependent exchange of intracellular Mg
2+
with extracellular Mg
2+
or Co
2+
is inhibited by colicin E1 and, less strongly, by colicin K. Treatment with either colicin causes a net loss of intracellular Mg
2+
. This loss begins immediately in cells treated with colicin E1, but in colicin K-treated cells the onset of Mg
2+
loss is delayed 1 to 10 min, depending upon the temperature and the multiplicity of colicin K. Both colicins differ from chemical inhibitors of energy-yielding metabolism; energy poisons block transport of Mg
2+
and Co
2+
, but both colicins increase passive permeability to Mg
2+
and Co
2+
. Inhibitors of energy-yielding metabolism (and of Mg
2+
exchange) block the initiation of Mg
2+
loss by either colicin, but do not stop colicin-promoted efflux once it has begun. Colicin E1 added before colicin K prevents the more rapid Mg
2+
efflux characteristic of colicin K-treated cells. Quantitative comparisons of the effects of colicins E1 and K upon permeability to Mg
2+
and Co
2+
lead us to conclude that the two colicins are not identical in their mode of action.
Degradation of Bacteriophage Lambda Deoxyribonucleic Acid After Restriction by
Escherichia coli
K-12
Authors: Simmon Vincent F. , Lederberg Seymour
Published: January 2020

Wild-type bacteria which restrict the deoxyribonucleic acid (DNA) of infecting phage when the phage do not carry the proper host modification rapidly degrade that restricted DNA to acid-soluble products. The purified restriction enzyme acts as an endonuclease in vitro to cleave restrictable DNA and does not further degrade the DNA fragments produced. We have examined mutants of
Escherichia coli
K-12 which lack various nucleases in order to determine which nucleases are involved in the rapid acid solubilization in vivo of unmodified λ DNA following restriction. Bacteria which are wild type,
recA
−
, or
polA1
−
degrade about 50% of the unmodified phage DNA within 10 min of infection, with little subsequent degradation. Mutants which are
recB
−
or
recC
−
degrade unmodified DNA very slowly, solubilizing about 15% of the DNA by 10 min after infection. Two classes of phenotypic revertants of
recB
−
/
C
−
mutants were also tested. Bacteria which are
sbcA
−
restrict poorly and do not degrade much of the restricted DNA. Bacteria which are
sbcB
−
restrict normally. This mutation does not appear to affect degradation of restricted phage DNA in
recB
−
/
C
−
mutants, but such degradation is decreased in
recB
+
/
C
+
bacteria. The presence of a functional λ exonuclease gene is not required for degradation after restriction.
A 3, 5-Diaminohexanoate-Decomposing
Brevibacterium
Authors: Hong Su-Chen L. , Barker H. A.
Published: January 2020

An obligately aerobic bacterium that grows on
dl
-erythro-3, 5-diaminohexanoate as a sole carbon, nitrogen, and energy source was isolated by the enrichment culture method. The organism utilizes only the
l
isomer by means of an inducible enzyme system. The organism has been tentatively identified as a member of the genus
Brevibacterium
.
Gluconate Regulation of Glucose Catabolism in
Pseudomonas fluorescens
Authors: Quay S. C. , Friedman S. B. , Eisenberg R. C.
Published: January 2020

Induction of Entner-Doudoroff pathway enzymes in
Pseudomonas fluorescens
was investigated to study the role of gluconate as a possible inducer. Glucose oxidase-deficient mutants were isolated and characterized. One of these mutants, gox-7, was deficient in particulate glucose oxidase; another mutant, gox-17, was deficient in particulate glucose and gluconate oxidase activities. Gluconate, but not glucose, induced synthesis of gluconokinase and 6-phosphogluconate dehydratase in both mutants. High constitutive levels of 2-keto-3-deoxy-6-phosphogluconate aldolase were found when both mutants were grown on glucose. Growth of parent and both mutant strains on glycerol also resulted in high levels of Entner-Doudoroff pathway enzymes. It was concluded that glucose cannot serve as an inducer molecule for derepression of Entner-Doudoroff pathway enzymes in
P. fluorescens
. Evidence presented provides good support for gluconate being the true inducer of this pathway in
P. fluorescens
. A relationship is presented for explaining distribution of the Entner-Doudoroff pathway in certain groups of bacteria.
Cysts of
Azotobacter vinelandii
with Double Coats
Authors: Cagle Gerald D. , Vela G. R.
Published: January 2020

Cyst germination was studied in cultures of
Azotobacter vinelandii
ATCC 12837. The existence of cysts enclosed by double coats is described.
Synchronized Division in
Escherichia coli
: an Integral Portion of Culture Growth
Authors: Ricciuti C. Propst
Published: January 2020

A single synchronized division normally occurs in
Escherichia coli
just prior to stationary phase, irrespective of growth medium and lineage or sex of the bacterium.
Toxicity of
l
-Tryptophan Photoproduct on Recombinationless (
rec
) Mutants of
Salmonella typhimurium
Authors: Yoakum G. , Eisenstark A.
Published: January 2020

l
-Tryptophan after exposure to black light becomes toxic for recombinationless (
rec
) mutants of
Salmonella typhimurium
. Fifty-six radiation-sensitive mutants were screened for sensitivity to the tryptophan photoproduct; the
rec
and
exr
(X-ray sensitive) mutants are sensitive, whereas the
uvr, hcr
, and wild-type strains are resistant. A number of catabolic products of tryptophan and compounds related to tryptophan were screened for toxicity to
rec
strain; these are nontoxic or far less toxic for
rec
strains than irradiated
l
-tryptophan. The toxic photoproduct is relatively stable to drying and basic hydrolysis at 90 C, indicating that it is a stable organic compound, eliminating peroxide as the toxic component. It was also observed that the toxic product is a photooxidation product since it is formed only when
l
-tryptophan is irradiated in the presence of air.
Genetic Basis of the Biodegradation of Salicylate in
Pseudomonas
Authors: Chakrabarty A. M.
Published: January 2020

The genetic basis of the biodegradation of salicylate in
Pseudomonas putida
R1 has been studied. This strain utilizes the
meta
pathway for oxidizing salicylate through formation of catechol and 2-hydroxymuconic semialdehyde. The enzymes of the
meta
pathway are induced by salicylate but not by catechol, and the genes specifying these enzymes are clustered. The gene cluster can be eliminated from some salicylate-positive cells by treatment with mitomycin C and appears to exist inside the cell as an extrachromosomal element. This extrachromosomal gene cluster, termed the SAL plasmid, can be transferred by conjugation from
P. putida
R1 to a variety of other
Pseudomonas
species.
Dominant Mutations (
lex
) in
Escherichia coli
K-12 Which Affect Radiation Sensitivity and Frequency of Ultraviolet Light-Induced Mutations
Authors: Mount David W. , Low K. Brooks , Edmiston Susan J.
Published: January 2020

Three mutations, denoted
lex-1, -2
and
-3
, which increase the sensitivity of
Escherichia coli
K-12 to ultraviolet light (UV) and ionizing radiation, have been found by three-factor transduction crosses to be closely linked to
uvrA
on the
E. coli
K-12 linkage map. Strains bearing these mutations do not appear to be defective in genetic recombination although in some conjugational crosses they may fail to produce a normal yield of genetic recombinants depending upon the time of mating and the marker selected. The mutagenic activity of UV is decreased in the mutant strains. After irradiation with UV, cultures of the strains degrade their deoxyribonucleic acid at a high rate, similar to
recA
−
mutant strains. Stable
lex
+
/
lec
−
heterozygotes are found to have the mutant radiation-sensitive phenotype of haploid
lex
−
strains.
Polycistronic Effects of Catabolite Repression on the
lac
Operon
Authors: Silverstone Allen E. , Magasanik Boris
Published: January 2020

The catabolite repression caused by glucose and glucose-6-phosphate has been studied for both β-galactosidase and thiogalactoside transacetylase, the products of the operator proximal and distal cistrons of the
lac
operon, respectively. We find that both cistrons are affected coordinately by this form of repression. We also find that a single alteration at the
lac
promoter region is sufficient to abolish sensitivity to repression of both cistrons. From this, we conclude that there is only one target site for catabolite repression in the
lac
operon.
Excision Repair Characteristics of
recB
−
res
−
and
uvrC
−
Strains of
Escherichia coli
Authors: Kato Takesi
Published: January 2020

An
Escherichia coli
strain carrying the
recB21
and
res-1
mutations showed an abnormally low level of colony-forming ability although it grew essentially normally in liquid medium. The
recB21 res-1
strain showed little, if any, of the ultraviolet (UV)-induced deoxyribonucleic acid (DNA) breakdown characteristic of the
res-1
mutant. Nevertheless, the double mutant was far more sensitive to UV than either the
res-1
or the
recB21
strain. When compared with a wild-type strain, the rate of release of dimers from UV-irradiated DNA was very slow in the
recB21 res-1
, but normal in the
res-1 recB
+
or
recB21 res
+
mutants. However, the ratio of dimer-to-thymine released into the acid-soluble fraction was three times higher than the wild type in
recB21 res
+
and
recB21 res-1
and only one-tenth as high as the wild type in
res-1 rec
+
. Alkaline sucrose gradient centrifugation revealed occurrence of single-strand incision of UV-irradiated DNA and the restitution of nicked DNA at a similar rate in the
recB21 res-1
and
recB21 res
+
strains. Mutants
uvrC
−
showed increased amounts of nicks in their DNA with increasing incubation time after UV irradiation, although no detectable amounts of dimers were excised from UV-irradiated DNA. From these results, it is concluded that the increased sensitivity of the
res-1
strain to UV light is due to a reduced ability to excise dimers from UV-irradiated DNA and that the high rate of UV-induced breakdown of DNA is not the primary cause. A possible role of
uvrC
gene in the excision repair is discussed.
Carbon Monoxide Production from Heme Compounds by Bacteria
Authors: Engel Rolf R. , Matsen John M. , Chapman S. Stephen , Schwartz Samuel
Published: January 2020

Carbon monoxide formation from heme compounds by bacteria was investigated to study microbial hemoprotein catabolism with reference to heme degradation by mammalian tissues. Hemolytic and nonhemolytic bacteria were incubated aerobically and anaerobically with the following substrates: erythrocytes, hemoglobin, myoglobin, cytochromec, hematin, iron hematoporphyrin, copper hematoporphyrin, protoporphyrin, and bilirubin. After 18 hr at 37 C the evolved CO was measured by gas chromatography. None of the bacteria formed CO anaerobically. Under aerobic conditions both alpha-hemolyticStreptococcus mitisand hemolyticBacillus cereusformed CO from all of the heme compounds tested, whereas nonhemolyticStreptococcus mitisdid not evolve CO from any of the substrates. The hemolytic bacteria did not produce CO when the iron of heme was either replaced by copper or removed, as in copper hematoporphyrin and in protoporphyrin, respectively.
Mechanism of Inhibition of Deoxyribonucleic Acid Synthesis in
Escherichia coli
by Hydroxyurea
Authors: Sinha Navin K. , Snustad D. P.
Published: January 2020

The effects of hydroxyurea on
Escherichia coli
B/5 physiology (increases in cell mass, number of viable cells, and deoxyribonucleic acid [DNA], RNA, and protein concentrations) were studied in an attempt to find a concentration that completely inhibits DNA synthesis and increase in number of viable cells but has little or no effect on other metabolic processes. These conditions were the most closely approached at an hydroxyurea concentration of 0.026 to 0.033
m
. A concentration of 0.026 or 0.033
m
was used in subsequent experiments to study the site(s) of inhibition of DNA synthesis in
E. coli
B/5 by hydroxyurea. Hydroxyurea at a concentration of 10
−2
m
was found to inhibit ribonucleoside diphosphate reductase activity completely in crude extracts of
E. coli
. The synthesis of deoxyribonucleotides was greatly reduced when
E. coli
cells were grown in the presence of 0.033
m
hydroxyurea. Studies on the acid-soluble DNA precursor pools showed that hydroxyurea causes a decrease in the concentration of deoxyribonucleoside diphosphates and deoxyribonucleoside triphosphates and an increase in the total concentration of ribonucleotides. Sucrose density gradient sedimentation of DNA from cells treated with 0.026
m
hydroxyurea for 30 min indicated that at this concentration hydroxyurea induces no detectable single- or double-strand breaks. In addition, both replicative and repair syntheses of DNA were found to occur normally in toluene-treated cells in the presence of relatively high concentrations of hydroxyurea. Pulse-chase studies showed that deoxyribonucleotides synthesized prior to the addition of hydroxyurea to cells are utilized normally for DNA synthesis in the presence of hydroxyurea. On the basis of these observations, we have concluded that the primary, if not the only, site of inhibition of DNA synthesis in
E. coli
B/5 by low concentrations of hydroxyurea is the inhibition of the enzyme ribonucleoside diphosphate reductase.
Phenoxazinone Synthetase from
Streptomyces antibioticus
: Multiple Activities of the Enzyme
Authors: Golub Ellis E. , Nishimura Jonathan S.
Published: January 2020

A procedure for the preparation of relatively large quantities of highly purified phenoxazinone synthetase from
Streptomyces antibioticus
is described. Enzyme preparations consisted of multiple forms, as determined by polyacrylamide gel electrophoresis. Each of the electrophoretically separable forms catalyzed the oxidation of catechols, ferrocyanide, and ethylenic thiols, in addition to
o
-aminophenols.
Scanning Electron Microscopy of Ascospores of
Schwanniomyces
Authors: Kurtzman C. P. , Smiley M. J. , Baker F. L.
Published: January 2020

Ascospores of the four recognized species of
Schwanniomyces
were examined by scanning electron microscopy. Spores of
S. alluvius, S. castellii
, and
S. occidentalis
, which were essentially identical, had abundant, long protuberances and wide, thin equatorial rings. The two known strains of
S. persoonii
differed from the other species as well as from each other. One strain had spores with a wide ring but only a few short protuberances; spores from the second strain were covered with craterlike depressions and had a narrow ring. Also examined were spores of
Schwanniomyces hominis
(=
Saccharomyces rosei
) which lacked a ring and were covered with short irregularly shaped protuberances, a finding consistent with the morphology of spores from other strains of
S. rosei
.
Isolation of 4′-Hydroxyechinenone from
Micrococcus roseus
Authors: Schwartzel E. M. , Cooney J. J.
Published: January 2020

The carotenoid 4′-hydroxyechinenone (4′-hydroxy-β, β-carotene-4-one) was isolated from
Micrococcus roseus
. It is proposed as an intermediate between echinenone and canthaxanthin.
Ultraviolet-Sensitive Mutator Strain of
Escherichia coli
K-12
Authors: Siegel Eli C.
Published: January 2020

An ultraviolet (UV)-sensitive mutator gene,
mutU
, was identified in
Escherichia coli
K-12. The mutation
mutU4
is very close to
uvrD
, between
metE
and
ilv
, on the
E. coli
chromosome. It was recessive as a mutator and as a UV-sensitive mutation. The frequency of reversion of
trpA46
on an F episome was increased by
mutU4
on the chromosome. The mutator gene did not increase mutation frequencies in virulent phages or in lytically grown phage λ. The
mutU4
mutation predominantly induced transitional base changes. Mutator strains were normal for recombination and host-cell reactivation of UV-irradiated phage T1. They were normally resistant to methyl methanesulfonate and were slightly more sensitive to gamma irradiation than Mut
+
strains. UV irradiation induced mutations in a
mutU4
strain, and phage λ was UV-inducible. Double mutants containing
mutU4
and
recA, B
, or
C
were extremely sensitive to UV irradiation; a
mutU4 uvrA6
double mutant was only slightly more sensitive than a
uvrA6
strain. The
mutU4 uvrA6
and
mutU4 recA, B
, or
C
double mutants had mutation rates similar to that of a
mutU4
strain. Two UV-sensitive mutators,
mut-9
and
mut-10
, isolated by Liberfarb and Bryson in
E. coli
B/UV, were found to be co-transducible with
ilv
in the same general region as
mutU4
.
Fine Structure of
Methanobacterium thermoautotrophicum:
Effect of Growth Temperature on Morphology and Ultrastructure
Authors: Zeikus J. G. , Wolfe R. S.
Published: January 2020

The fine structure of
Methanobacterium thermoautotrophicum
which was grown at the optimal temperature, 65 C, as well as at the temperature extremes for growth is described. The most distinguishing feature of this organism is the presence of intracytoplasmic membranes. The internal membrane system consists of triplet membranes which are stacked closely together, frequently appearing as concentric circles without separation by cytoplasm. Aside from this feature,
M. thermoautotrophicum
proliferates as irregularly curved rods at 65 C and has a fine structure similar to most other gram-positive bacteria. Both low (45 C) and high (75 C) growth temperatures induce structural modifications. These structural changes include rod to spheroidal morphological changes, cell wall abberations, distortion of division septa, misdivisions, and internal membrane deterioration.
Osmotic Reversal of Temperature Sensitivity in
Escherichia coli
Authors: Bilsky Anna Z. , Armstrong John B.
Published: January 2020

Forty temperature-sensitive mutants, unable to grow on tryptone or nutrient agar at 42 C, were isolated from
Escherichia coli
K-12. When 0.5% NaCl was added to the medium, 32 grew at the nonpermissive temperature. Several were tested with different amounts of NaCl added to tryptone broth; all grew best when the osmolality of the medium was between 400 and 1,000 milliosmolal. One of the mutants was studied in more detail. Sucrose, inositol, KCl, and MgCl
2
, as well as NaCl, permitted growth at 42 C. Glycerol, however, had no effect. When shifted from 30 to 42 C without osmotic protection, the mutant stopped growing but did not lyse, die, or leak significant amounts of intracellular material. In a similar shift experiment, a second mutant leaked all of its trichloroacetic acid-soluble pools into the medium. The majority of the mutants were hypersensitive to certain antibiotics, indicating possible cell envelope defects.
Volatilization of Mercuric Chloride by Mercury-Resistant Plasmid-Bearing Strains of
Escherichia coli, Staphylococcus aureus
, and
Pseudomonas aeruginosa
Authors: Summers Anne O. , Lewis Elaine
Published: January 2020

Several bacterial strains carrying genes determining mercury resistance on naturally occurring plasmids will convert 10
−5
m
Hg
2+
(chloride) to a form of mercury which is volatile and soluble in organic solvents. The volatilization activity is induced by exposure to HgCl
2
.
Preliminary Mapping of Mutations Affecting Exonuclease III in
Escherichia coli
K-12
Authors: Milcarek Christine , Weiss Bernard
Published: January 2020

xthA
, a structural gene for exonuclease III in
Escherichia coli
K-12, is cotransducible with
aroD, aroH
, and
pps
.
Differential Gene Action in
Neurospora crassa
Authors: Bhagwat A. S. , Mahadevan P. R.
Published: January 2020

Molecular hybridization experiments with pulse-labeled total ribonucleic acid (RNA) or isolated nonribosomal rapidly labeled RNA species and deoxyribonucleic acid from growth periods of 8, 16, and 24 hr of
Neurospora crassa
showed differential transcription. Hybridization competition experiments between RNA species isolated from 8, 16, and 24 hr of growth showed qualitative differences in the types of RNA synthesized during these periods.
Relationships Among Mycobacteria and Nocardiae Based upon Deoxyribonucleic Acid Reassociation
Authors: Bradley S. G.
Published: January 2020

The degree of renaturation between
Nocardia farcinica
330 deoxyribonucleic acid (DNA) and DNA from 17 nocardial strains and 11 mycobacterial strains, and between
Mycobacterium smegmatis
405 DNA and DNA from 11 mycobacterial strains and 14 nocardial strains was determined by using the nitrocellulose membrane filter technique. These results indicated that some cultures designated
N. farcinica
were identical to some cultures designated
N. asteroides
but that other strains called
N. asteroides
were distinctly different. The species
M. smegmatis
was homogeneous and distinct from the other species examined. Data comparing the extent of nucleotide sequences shared by
M. smegmatis
405 DNA and DNA from nine other mycobacterial strains, as determined by the membrane filter technique and by monitoring DNA reassociation optically, were similar. The extent of reassociation between
M. tuberculosis
H37Ra DNA and DNA from 14 mycobacterial strains was determined optically. DNA from
M. bovis
BCG was 86% homologous with
M. tuberculosis
H37Ra DNA. The other mycobacterial DNA preparations examined were less than 40% homologous with
M. tuberculosis
H37Ra DNA. The genome sizes of the mycobacteria examined ranged between 2.5 × 10
9
daltons and 4.5 × 10
9
daltons.
Glucose-1-Phosphate-Negative Mutant of
Agrobacterium tumefaciens
Authors: Miyairi Sachio , Fukui Sakuzo
Published: January 2020

Glucose-1-phosphate-negative mutants that are unable to grow in a synthetic medium containing glucose-1-phosphate (G-1-P) as a sole carbon source were isolated by treatment of
Agrobacterium tumefaciens
IAM 1525 with
N
-methyl-
N
′-nitro-
N
-nitrosoguanidine. All of the enzymes involved in G-1-P metabolism (glucoside-3-dehydrogenase, 3-ketoglucose-1-phosphate-degrading enzyme, α-glucosidase, and phosphatases) were detected in the sonic extract prepared from resting cells of one of the mutants, strain M-24, in approximately equal levels to those in the parent strain. Resting cells of the mutant oxidized G-1-P to 3-ketoglucose-1-phosphate (3KG-1-P), the first product in G-1-P metabolism by the bacterium, with little subsequent degradation, whereas the parent showed further degradation of G-1-P via 3KG-1-P. Glucoside-3-dehydrogenase catalyzing 3-ketoglucoside formation was readily released from cells by osmotic shock, whereas the 3KG-1-P-degrading enzyme was not released. Thus, the former and the latter enzymes might be at different intracellular loci, such as periplasm and cytoplasm, respectively. It is suggested that the mutant strain M-24 is a G-1-P-negative mutant deficient in a 3KG-1-P transport system located on the cytoplasmic membrane.
Divalent Cations in Native and Reaggregated Mycoplasma Membranes
Authors: Kahane Itzhak , Ne'Eman Zvi , Razin Shmuel
Published: January 2020

The Mg
2+
content of membranes of several
Mycoplasma
and
Acholeplasma
species varied between 0.88 and 1.98 μg of Mg
2+
per mg of protein, depending on the species and on growth conditions. Ca
2+
could be detected only when it was added to the growth medium. The Mg
2+
content of isolated
A. laidlawii
membranes could be increased almost threefold by dialysis against 20 m
m
Mg
2+
, whereas aggregated
A. laidlawii
membranes contained about six to eight times more Mg
2+
per mg of protein than the native membranes. This was taken to indicate that the molecular organization of the lipid and protein in the reaggregated membranes differs from that of the native membranes. Between 60 and 83% of the Mg
2+
in native and reaggregated
A. laidlawii
membranes was associated with the lipid fraction extracted with chloroform-methanol. The removal of over 80% of membrane protein by Pronase digestion did not release any significant amount of Mg
2+
. Hence, most of the divalent cation appears to be bound to membrane lipids, most probably to phospholipids. Ethylenediaminetetraacetic acid released the bulk of Mg
2+
bound to the native and reaggregated
A. laidlawii
membranes, except for about 0.5 μg of Mg
2+
per mg of protein which was too tightly bound. Hence, a small but fairly constant amount of Mg
2+
is unavailable for chelation.
Kinetics and Regulation of the Salt-Dependent Aspartate Transcarbamylase of
Halobacterium cutirubrum
Authors: Norberg P. , Kaplan J. G. , Kushner D. J.
Published: January 2020

Properties of the aspartate transcarbamylase of the extremly halophilic bacterium
Halobacterium cutirubrum
, an enzyme that needs high salt concentrations for activity and regulation, were studied in cell-free extracts. The enzyme was stable on prolonged incubation at 4 C in concentrated extracts (50 mg of protein per ml) but not in diluted extracts. Mg
2+
ions and β-mercaptoethanol stabilized enzyme activity. At salt concentrations below the maximum for activity (3.5
m
), the enzyme was rapidly inactivated. Carbamyl phosphate stabilized the enzyme under these conditions; aspartate had a smaller effect. The enzyme was most stable at 0 C; raising or lowering the temperature from this point increased the rate of inactivation. On exposure to lowered salt concentrations, enzyme activity was more sensitive than feedback inhibition. Hyperbolic substrate saturation curves were found for carbamyl phosphate. The
K
m
obtained varied with the salt concentration used. With aspartate, sigmoidal curves were found when extracts were assayed immediately after preparation, but hyperbolic curves were obtained with extracts allowed to stand 1 to 2 hr. The presence of cytidine triphosphate (CTP) decreased the
V
max
but did not change the
K
m
; this is thus a V-type enzyme. Low concentrations of succinate activated the enzyme, in the presence and absence of CTP; higher concentrations did not affect its activity. CTP increased the activation energy of the enzyme in 3.5
m
salt but decreased it in 2.0
m
salt. At both salt concentrations, the sensitivity of the enzyme to feedback inhibition diminished with increasing temperatures. Gel chromatography suggested that the enzyme in crude extracts had a molecular weight of 160,000. Precipitating the enzyme with polyethylene glycol decreased the molecular weight to 34,000, and this activity was no longer sensitive to CTP. The presence of either substrate of the enzyme during polyethylene glycol treatment prevented dissociation of the enzyme and loss of feedback inhibition. Thus, as with other aspartate transcarbamylases, association of subunits seems to be required for regulation of activity by end product.
Interactions ofTetrahymena pyriformis, Escherichia coli, Azotobacter vinelandii, and Glucose in a Minimal Medium
Authors: Jost J. L. , Drake J. F. , Fredrickson A. G. , Tsuchiya H. M.
Published: January 2020

A study was made of the food web formed from a protozoon, two bacteria, and a glucose minimal medium in chemostat culture. The system was also divided into simpler parts, first by omitting the protozoon to obtain a competition system, and then by omitting one or the other of the bacteria to obtain two food chains. In the competition studies, one bacterium was displaced by the other at all holding times used. In the food chain studies, sustained oscillations of the population densities of predator and prey developed at short holding times, and then changed to damped oscillations at longer holding times. In addition, the level of residual glucose remained high at long holding times. A new model of microbial growth is necessary to explain these results. In the food web studies, predation of the protozoon on the two bacteria stabilized the competition between the latter and allowed their coexistence in the same habitat. Thus, Gause's principle was circumvented.
Effect of Halofenate and Clofibrate on Growth and Lipid Synthesis in
Saccharomyces cerevisiae
Authors: Greenspan Michael D. , Germershausen John I.
Published: January 2020

Halofenate-free acid (HFA) inhibited the growth of
Saccharomyces cerevisiae
by 50% at a concentration of 0.34 m
m
. This inhibitory effect was prevented by addition of either oleate or acetate, but not by pyruvate. When cell growth was supported by oleate, HFA inhibited the incorporation of radioactive carbon from glucose-
U
-
14
C
or pyruvate-
2
-
14
C
into fatty acids and sterols. The incorporation of radioactive carbon into fatty acids and sterols from acetate-
2
-
14
C
was unaffected by the compound. When cell growth was supported by either oleate or acetate, HFA inhibited the conversion of pyruvate-
1
-
14
C
to
14
CO
2
. These results suggest that HFA inhibits the conversion of pyruvate to acetate in yeast. Partially purified yeast pyruvate dehydrogenase was inhibited 50% by 5.5 m
m
HFA; however, the concentration required for 50% inhibition was considerably reduced when the enzyme was preincubated with the compound at room temperature. In a similar manner, the hypolipidemic agent clofibrate-free acid inhibited the growth of yeast by 50% at 3.0 m
m
. This inhibition was also prevented by acetate and not by pyruvate. In addition, clofibrate-free acid inhibited partially purified pyruvate dehydrogenase by 50% at a concentration of 37.0 m
m
.
The 503-nm Pigment of
Escherichia coli
B: Characterization and Nutritional Conditions Affecting Its Accumulation
Authors: Olden Kenneth , Hempfling Walter P.
Published: January 2020

Escherichia coli
B was shown to contain a pigment with a single symmetrical absorption band at 503 nm, which cannot be attributed to a cytochrome. The absorption of tetrahydroporphyrin in vitro closely resembled that of P-503 in intact cells. The compounds which rendered P-503 colorless, such as cyanide, azide, hydrazine, thiocyanate, hydroxylamine, dithionite, sulfite, and methylcyanide, also rendered tetrahydroporphyrin colorless. The pigment was present when the cells were grown aerobically or anaerobically in glucose minimal medium, or aerobically in either lactate or succinate minimal medium, but the pigment was not found in cells grown in complex media or in minimal media supplemented with methionine. A model is presented to suggest the involvement of methionine in the conversion of coproporphyrinogen to protoporphyrin. A variety of evidence suggesting that the 503-nm chromophore is in kinetic equilibrium with flavoprotein is discussed. However, it is not a participant in main line respiration, as its rate of reduction upon exhaustion of oxygen was too slow, and the rate of respiration in resting-cell suspensions was independent of P-503 concentration.
Role of Glutathione in the Morphogenesis of the Bacterial Spore Coat
Authors: Cheng H. M. , Aronson A. I. , Holt S. C.
Published: January 2020

There is a marked increase in the half-cystine content of bacterial spores, especially the coat layers at the time of formation of the outer coat. When a cysteine auxotroph of
Bacillus cereus
T is grown on limiting cysteine, the spores contain the normal content of half-cystine, suggesting an alternate source. Glutathione appears to be such a supply of cysteine since it is hydrolyzed during sporulation and there are increased activities of the hydrolyzing enzymes at the same time. In addition, a cysteine auxotroph with a second alteration, a temperature-sensitive glutathione disulfide reductase, produces lysozyme-sensitive spores at 40 C. These spores appear to be defective in the formation of outer spore coat. During sporulation at 40 C, the double mutant accumulates oxidized glutathione which is a poor substrate for the hydrolytic enzymes. As a result, sporulating cells are deficient in half-cystines which are essential for outer spore coat morphogenesis. This alteration can be overcome by a shift to 30 C or by addition of cystinyl-pencillamine or cysteinyl-glycine to cultures sporulating at 40 C.
Relation Between Survival and Deoxyribonucleic Acid Replication in Ultraviolet-Irradiated Resistant and Sensitive Strains of
Escherichia coli
B/r
Authors: Rudé J. M. , Doudney C. O.
Published: January 2020

When arabinose-grown
Escherichia coli
B/r is ultraviolet (UV) irradiated in the logarithmic phase of growth, the dose inactivation curve for both colony formation and deoxyribonucleic acid (DNA) synthesis (based on the relative rates of synthesis) is exponential in nature. When protein synthesis is inhibited before UV-irradiation, both inactivation curves have a large shoulder. Pre-irradiation inhibition of protein synthesis increases considerably the colony-forming ability of a UV-irradiated Hcr
−
and Rec
−
strain of
E. coli
B/r. However, with the repair-deficient strains, both the shoulder and slope of the survival curve are affected. We investigated the effect of UV irradiation on DNA synthesis in Hcr
−
bacteria and found that pre-irradiation inhibition of protein synthesis increases UV resistance of DNA replication in this strain also. The results suggest that inhibition of protein synthesis before irradiation increases UV resistance in
E. coli
B/r by a mechanism which is independent of both the excision and recombination repair systems.
Regulation of Manganese Accumulation and Exchange in
Bacillus subtilis
W23
Authors: Fisher Susan , Buxbaum Larry , Toth Kathleen , Eisenstadt Eric , Silver Simon
Published: January 2020

An overnight culture of
Bacillus subtilis
W23 in low-manganese tryptone broth is unable to sporulate and becomes hyperactive with regard to the manganese active transport system during stationary phase. When manganese is added to cells in spent or fresh medium, the cells immediately accumulate a high proportion of the manganese available in the medium. When the hyperactive cells are diluted into broth containing 10 μM Mn
2+
, high intracellular manganese levels are reached, and inhibition of ribonucleic acid and protein synthesis occurs. This inhibition is relieved when the intracellular manganese concentration declines to the nontoxic levels characteristic of cells growing in 10 μM Mn
2+
. The release of the accumulated manganese is achieved by a reduction in the uptake rate for manganese while the efflux rate remains essentially constant. Inhibitors of ribonucleic acid and protein synthesis prevent the reduction of the high rate of manganese uptake and, therefore, high net concentrations of manganese are maintained in the presence of these inhibitors. The hyperactive manganese uptake system is temperature dependent and inhibited by cyanide and
m
-chlorophenyl carbonylcyanide hydrazone.
Fine Structure of
Cryptococcus neoformans
Grown In Vitro as Observed by Freeze-Etching
Authors: Takeo K. , Uesaka I. , Uehira K. , Nishiura M.
Published: January 2020

Cryptococcus neoformans
grown on culture media was observed by the freeze-etching technique. In the capsule, short fibrils were seen when freezeetched. This organism was unique in the appearance of the cell wall, which showed two strata. The outer one was dense with particles of about 20 nm in diameter, whereas the inner one was sparse in particles. The appearance of the cell membrane of this organism differed distinctly depending on the culture media. When grown on glycerol medium, the cell membrane possessed, as do other yeasts, clear but somewhat longer and curved invaginations. The membrane of cells grown on nonglycerol medium exhibited, however, only a few invaginations of irregular shape. Instead, characteristically of this organism, the cell membrane showed round depressions of 40 to 200 nm in diameter which were the surface view of the paramural bodies. In cross-fractured cells, both types of paramural bodies were found. Some of them contained a single vesicle of about 50 nm in diameter. These seem to play a role in secreting the cytoplasmic vesicles. Data suggesting the existence of multivesicular bodies in the cytoplasm and multivesicular lomasomes were also obtained. Some of the baglike paramural bodies showed multilayered membrane. These are thought to be plasmalemmasomes. This organism was similar to other yeasts reported in other respects.