bluuebunny/crossref_metadata_2025 huggingface dataset:
Evidence That Tryptophanyl Transfer Ribonucleic Acid Is Not the Corepressor of the Tryptophan Operon of
Escherichia coli
Authors: Mosteller Raymond D. , Yanofsky Charles
Published: January 2020

When a growing culture of a tryptophan auxotroph of
Escherichia coli
is transferred to a tryptophan-free medium, the bacteria exhaust their supply of Trp-transfer ribonucleic acid (tRNA). Under these conditions transcription of the
trp
operon is derepressed. When
l
-tryptophan,
dl
-4-methyltrytophan,
dl
-6-methyltryptophan, or
dl
-7-azatryptophan is added to a tryptophan-starved culture, charging to tRNA
Trp
can be detected with each of these compounds except 6-methyltryptophan. Under these conditions, transcription initiations on the
trp
operon are repressed completely by tryptophan, 4-methyltryptophan, and 6-methyltryptophan, but only slightly by 7-azatryptophan. If a culture of a bacterium containing an altered tryptophanyl-tRNA synthetase (
trpS
−
) is starved for tryptophan in the same manner, tRNA
Trp
is uncharged, but transcription of the operon is derepressed to only about one-third the level observed in
trpS
+
cultures. When tryptophan, 4-methyltryptophan, 6-methyltryptophan, or 7-azatryptophan is added to a tryptophan-starved
trpS
−
culture, tRNA
Trp
is charged with tryptophan but apparently not with the analogues. However, tryptophan, 4-methyltryptophan, and 6-methyltryptophan completely repress transcription initiations, whereas 7-azatryptophan
derepresses
transcription initiations to approximately the level of partial repression observed in
trpS
+
cultures in the presence of 7-azatryptophan. When tryptophan is added to a tryptophan-starved
trpS10110
culture, there is a 2-min delay before tRNA
Trp
appears to be charged. However, under these conditions, transcription initiations on the
trp
operon are repressed immediately by the addition of tryptophan. We interpret these results as indicating that Trp-tRNA is not the corepressor of the
trp
operon.
Electron Microscopic Observations on the Structure of the Envelopes of Mature Elementary Bodies and Developmental Reticulate Forms of
Chlamydia psittaci
Authors: Tamura A. , Matsumoto A. , Manire G. P. , Higashi N.
Published: January 2020

Purified suspensions of
Chlamydia psittaci
were prepared from L cells. Thin sections of intact elementary bodies and intact developmental reticulate bodies and of their purified envelopes were observed by electron microscopy. In both intact organisms and partially purified envelopes, two membranous structures, each appearing in electron micrographs as two darkly stained layers, were observed. In the elementary body sections, the outer membrane was round, apparently rigid, and was not soluble in 0.5% sodium dodecyl sulfate. The inner layer was irregular in shape and was completely removed by detergent treatment. We interpret these results to indicate that the outer rigid layer of the envelope is the cell wall and the inner layer is the cytoplasmic membrane. When the fragile reticulate body envelopes were similarly studied, the outer cell wall was clearly visible, and some evidence of an inner membrane was seen. After treatment with nucleases and detergent, all evidence of inner or cytoplasmic membrane was removed, but the outer cell wall remained. Thus, it appears that the cell wall of this organism is continuous throughout the growth cycle and that the fragility and lack of rigidity of the reticulate body cell is due to changes in chemical composition or structure of the cell wall.
Mutant of
Escherichia coli
K-12 Defective in
d
-Glucosamine Biosynthesis
Authors: Sarvas Matti
Published: January 2020

A mutant was isolated from a derivative of
Escherichia coli
K-12 after mutagenesis with
N
-methyl-
N
′-nitro-
N
-nitrosoguanidine. This mutant contained normal levels of 2-amino-2-deoxy-
d
-glucose-6-phosphate ketol-isomerase (deaminating) (EC 5.3.1.10), but no detectable activity of
l
-glutamine:
d
-fructose-6-phosphate amino-transferase (EC 2.6.1.16). It required either
N
-acetyl-
d
-glucosamine or
d
-glucosamine for growth, and went into rapid lysis when the supply of these compounds was exhausted. In medium containing 11% sucrose, the cells were converted into spheroplasts in the absence of
d
-glucosamine.
“In Vivo” Detection of
l
-Arabinose-Binding Protein, CRM-Negative Mutants
Authors: Hogg Robert W.
Published: January 2020

An “in vivo” assay for the detection of mutants negative to CRM (cross-reacting material) is described.
l
-Arabinose-negative mutants of
Escherichia coli
B/r were grown on Casamino Acids-
l
-arabinose plates to which a 3-ml agar layer, containing antiserum to the
l
-arabinose-binding protein (ABP), had been applied. After incubation and partial lysis of the clones “in situ,” the plates were refrigerated for 36 hr, rinsed of colonial growth with water, and observed for the presence or absence of an immune precipitation. ABP-minus and
l
-arabinose regulator (
araC
)-minus mutants do not produce a precipitin reaction.
l
-Arabinose isomeraseless (EC 5.3.1.4;
araA
), kinaseless (EC 2.7.1.16;
araB
), and epimeraseless (EC 5.1.3.a;
araD
) mutants produce precipitin reactions. Mutants of
E. coli
B/r generated by treatment of the wild type with ethyl methane sulfonate or ultraviolet irradiation were isolated, tested for
l
-arabinose uptake, and screened for the presence or absence of ABP by the described assay. The applications of such an assay are discussed.
Deoxycytidine Triphosphate Deaminase: Characterization of an
Escherichia coli
Mutant Deficient in the Enzyme
Authors: O'Donovan G. A. , Edlin G. , Fuchs J. A. , Neuhard J. , Thomassen E.
Published: January 2020

A mutant of
Escherichia coli
, previously shown to contain abnormal nucleoside triphosphate pools, was found to be defective in its ability to synthesize thymidine nucleotides. The defect is not in the enzyme thymidylate synthetase but in deoxycytidine triphosphate deaminase, an enzyme that supplies deoxyuridine monophosphate, the substrate for thymidylate synthetase.
Mechanism of
d
-Cycloserine Action: Transport Mutants for
d
-Alanine,
d
-Cycloserine, and Glycine
Authors: Wargel Robert J. , Shadur Craig A. , Neuhaus Francis C.
Published: January 2020

The accumulation of
d
-alanine and the accumulation of glycine in
Escherichia coli
are related and appear to be separate from the transport of
l
-alanine. The analysis of four
d
-cycloserine-resistant mutants provides additional support for this conclusion. The first-step mutant from
E. coli
K-12 that is resistant to
d
-cycloserine was characterized by the loss of the high-affinity line segment of the
d
-alanine-glycine transport system in the Lineweaver-Burk plot. This mutation, which is linked to the
met
1
locus, also resulted in the loss of the ability to transport
d
-cycloserine. The second-step mutation that is located 0.5 min from the first-step mutation resulted in the loss of the low-affinity line segment for the
d
-alanine-glycine transport system. The transport of
l
-alanine was decreased only 20 to 30% in each of these mutants. A multistep mutant from
E. coli
W that is 80-fold resistant to
d
-cycloserine lost >90% of the transport activity for
d
-alanine and glycine, whereas 75% of the transport activity for
l
-alanine was retained.
E. coli
W could utilize either
d
- or
l
-alanine as a carbon source, whereas the multistep mutant could only utilize
l
-alanine. Thus, a functioning transport system for
d
-alanine and glycine is required for both
d
-cycloserine action and growth on
d
-alanine.
Influence of Temperature on the Iron Metabolism of a Fluorescent Pseudomonad
Authors: Garibaldi J. A.
Published: January 2020

The iron requirement for maximal cell yields of a fluorescent pseudomonad increases as the temperature of incubation is increased. On a succinate salts medium, maximal cell yields are attained at iron concentrations of 0.10 μg/ml of added iron at 20 C and at 3.0 μg/ml of added iron at 28 C. This bacterium does not grow in the basal medium at 31 C even in the presence of 0.01 to 10 μg/ml of added iron. The inability to grow at the higher temperature is due to the loss, by this organism, of its ability to biosynthesize hydroxamate iron transport compounds at temperatures of 28 C and above, since supplementation with such compounds produced by this organism at lower temperatures promoted growth at 31 C. The biosynthesis of these compounds at lower temperatures contributes to the efficient utilization of iron by the bacterium.
Isolation and Chemical Composition of the Cytoplasmic Membrane of a Gram-Negative Bacterium
Authors: Martin Eugene L. , MacLeod Robert A.
Published: January 2020

With procedures developed previously in this laboratory, the various layers of the cell wall of a gram-negative bacterium, a marine pseudomonad (ATCC 19855), were removed completely giving rise to true protoplasts. Membranes were isolated from the protoplasts formed. After treatment with ribonuclease, deoxyribonuclease, and washing, the membranes isolated were shown by electron microscopy and chemical analysis to be essentially free from both wall material and cytoplasmic constituents. The membranes gave rise to a single compact band in a sucrose density gradient. All of the lipid and protein were found to be associated in the membrane band. Analysis showed the membranes to contain 30.5% lipid (78% of which was phospholipid), 62.8% protein, and 2% carbohydrate. The predominant phospholipid present was phosphatidylethanolamine with a lesser amount of diphosphatidylglycerol and traces of unidentified compounds.
Uptake of β-Galactosides by
Escherichia coli
at Elevated Atmospheric Pressure
Authors: Schlamm N. A. , Daily O. P.
Published: January 2020

Uptake of β-galactosides by
Escherichia coli
was increased by pressurization to 68 atm. The increase appeared to be due to an effect on the β-galactoside permeases.
Appearance of a Protein “Agglutinin” on the Spheroplast Membrane of Pneumococci During Induction of Competence
Authors: Tomasz Alexander , Zanati Eva
Published: January 2020

Competent pneumococci and their spheroplasts agglutinate in dilute acid. Agglutination is caused by a trypsin-sensitive agglutinin which is not identical to the competence factor and the appearance of which requires protein synthesis.
Comparative Physiological Studies of the Yeast and Mycelial Forms of
Histoplasma capsulatum
: Uptake and Incorporation of
l
-Leucine
Authors: Gupta Rishab K. , Howard Dexter H.
Published: January 2020

l
-Leucine entered the cells of both morphological forms of
Histoplasma capsulatum
by a permease-like system at low external concentrations of substrate. However, at levels greater than 5 × 10
−5
m l
-leucine, the amino acid entered the cells both through a simple diffusion-like process and the permease-like system. The rate of the amino acid diffusion into yeast and mycelial forms appeared to be the same, whereas the initial rate of accumulation through the permease-like system was 5 to 10 times faster in the mycelial phase than it was in the yeast phase. The Michaelis constants were 2.2 × 10
−5
m
in yeast phase and 2 × 10
−5
m
in mycelial phase cells. Transport of
l
-leucine at an external concentration of 10
−5
m
showed all of the characteristics of a system of active transport, which was dependent on temperature and
p
H. Displacement or removal of the α-amino group, or modification of the α-carboxyl group abolished amino acid uptake. The process was competitively inhibited by neutral aliphatic side-chain amino acids (inhibition constants ranged from 1.5 × 10
−5
to 6.2 × 10
−5
m
). Neutral aromatic side-chain amino acids and the
d
-isomers of leucine and valine did not inhibit
l
-leucine uptake. These data were interpreted to mean that the
l
-leucine transport system is stereospecific and is highly specific for neutral aliphatic side-chain amino acids. Incorporation of
l
-leucine into macromolecules occurred at almost the same rate in both morphological forms of the fungus. The mycelial phase but not the yeast phase showed a slight initial lag in incorporation. In both morphological forms the intracellular pool of
l
-leucine was of limited capacity, and the total uptake of the amino acid was a function of intracellular pool size. The initial rate of
l
-leucine uptake was independent of the level of intracellular pool. Both morphological forms deaminated and degraded only a minor fraction of the accumulated leucine.
Amino Acid-β-Naphthylamide Uptake by
Pseudomonas aeruginosa
Authors: Riley P. S. , Behal Francis J.
Published: January 2020

Studies on the arylamidase of
Pseudomonas aeruginosa
indicate that the enzyme is intracellular and constitutive. However, in cells grown in a basal salts medium, the uptake of amino acid-β-naphthylamide is induced by certain amino acids. The synthesis of protein(s) related to transport in response to exposure to amino acids is postulated since chloramphenicol completely inhibits the inducing effect of amino acids. The uptake of amino acid-β-naphthylamide is energy dependent, and the amino acid residue is incorporated into bacterial protein.
Chromosome Mapping of
Pasteurella pseudotuberculosis
by Interrupted Mating
Authors: Lawton William D. , Stull Harold B.
Published: January 2020

Pasteurella pseudotuberculosis
, containing the
Escherichia coli
plasmid F′
lac
, transferred its chromosome in an oriented manner to each of five multiply auxotrophic strains of
P. pseudotuberculosis
. In a mating system containing gelatin, glucose, and phosphate buffer, a maximum of 0.02% of the donor cells transferred lead markers. The donor population was counterselected with nalidixic acid. We established the entry time of seven markers as follows: proline (11 min); arginine (14 min); histidine (14 min); threonine (25 min); lysine (50 min); tyrosine (67 min); and tryptophan (77 min). However, an analysis of the inheritance of unselected markers did not support the simplest assumption that the chromosome was transferred as Origin...
pro... arg his... thr... lys... tyr... trp
.... The markers common to all five recipients,
arg
and
his
, were closely linked, but of the five other markers, each unique to a different recipient strain, only
trp
was linked to
arg
and
his
. Our data suggest that the
Pasteurella
chromosome is transferred in more than one linkage group.
Cotransduction of
strA
and Ribosomal Protein Cistrons in
Escherichia coli-Salmonella typhimurium
Hybrids
Authors: O'neil Dennis M. , Sypherd Paul S.
Published: January 2020

Genetic mapping of ribosomal protein cistrons of
Salmonella typhimurium
and
Escherichia coli
was performed by phage P1 mediated, generalized transduction. From an
E. coli
hybrid strain which carried a
S. typhimuirum
F′ factor, an
E. coli
strain was constructed which had integrated
S. typhimurium
genetic material including the region of the
strA
locus.
Salmonella
genetic material from this hybrid was transduced into
E. coli
recipients. The ribosomal protein electrophoretic patterns of these hybrid transductants were correlated with the presence of markers contributed by each parent.

The results of these studies indicate that cistrons for at least three characteristic
S. typhimurium
and two
E. coli
30
S
ribosomal proteins are closely linked to the
strA
locus on the genetic maps of both organisms. At least one cistron coding for a 50
S
ribosomal protein is also closely linked to this locus on both maps. These findings support the concept that cistrons coding for the ribosomal proteins are clustered in one area of the genome. Mutations to spectinomycin and streptomycin resistance are closely linked in
S. typhimurium
and are located at
strA
.
Lactate Metabolism by
Veillonella parvula
Authors: Ng Stephen K. C. , Hamilton Ian R.
Published: January 2020

A strain of
Veillonella parvula
M4, which grows readily in lactate broth without a requirement for carbon dioxide, has been isolated from the oral cavity. Anaerobic, washed cells of this organism fermented sodium lactate to the following products (moles/100 moles of lactate): propionate, 66; acetate, 40; carbon dioxide, 40; and hydrogen, 14. Cells grew readily in tryptone-yeast extract broth with pyruvate, oxaloacetate, malate, and fumarate, but poorly with succinate. The fermentation of pyruvate, oxaloacetate, or lactate plus oxaloacetate by washed cells resulted in the formation of propionate and acetate in ratios significantly lower than those observed with lactate as the sole carbon source. This was primarily due to increased acetate production. Cell-free extracts were unable to degrade lactate but metabolized lactate in the presence of oxaloacetate, indicating the presence of malic-lactic transhydrogenase in this organism. Lactic dehydrogenase activity was not observed. Evidence is presented for oxaloacetate decarboxylase and malic dehydrogenase activities in extracts.
Induction and Repression of
l
-Arabinose Isomerase in
Salmonella typhimurium
Authors: Bhattacharya A. K. , Chakravorty M.
Published: January 2020

As with other inducible enzymes, the induced synthesis of
l
-arabinose isomerase (
l
-arabinose ketol isomerase, EC 5.3.1.4) in
Salmonella typhimurium
is subject to catabolite repression. Of the three catabolite repressors tested, glucose produces maximum repression. Analogues of catabolite repressors like 2-deoxy-
d
-glucose and
d
-fucose also inhibit the synthesis of the enzyme. The catabolite repression is completely reversed in the presence of 1.5 × 10
−3
m
cyclic 3′,5′-adenosine monophosphate (AMP). The maximum repression is produced in glucose-grown cells in glucose-containing induction medium. Cyclic 3′,5-AMP reverses this repression provided that the cells are treated with ethylenediaminetetraacetic acid (EDTA). In normal cells, cyclic 3′,5′-AMP has no effect on the induction but in EDTA-treated cells the cyclic nucleotide enhances synthesis of the enzyme. The inhibition produced by
d
-fucose cannot be reversed by cyclic 3′,5′-AMP.
d
-Fucose competes with the inducer
l
-arabinose in some step(s) involved in the process of induction.
Tryptophanase-Positive Bacteria in the Marine Environment
Authors: Klug M. J. , DeMoss R. D.
Published: January 2020

The prevalence of indole-positive organisms in the gut and environment of marine animals was studied. Indole formation by a group of the isolates was found to occur only in the presence of tryptophan. The isolates examined were all assigned to the genus
Vibrio
.
Temperature Control of Phospholipid Biosynthesis in
Escherichia coli
Authors: Sinensky Michael
Published: January 2020

The higher the growth temperature of
Escherichia coli
cultures the greater is the proportion of saturated fatty acids in the bacterial phospholipids. When fatty acids are exogenously supplied to
E. coli
, higher growth temperatures will likewise increase the relative incorporation of saturated fatty acids into phospholipids. One of the steps in the utilization of fatty acids for phospholipid biosynthesis is, therefore, temperature-controlled. The temperature effect observed in vivo with mixtures of
3
H-oleate and
14
C-palmitate is demonstrable in vitro by using mixtures of the coenzyme A derivative of these fatty acids for the acylation of α-glycerol phosphate to lysophosphatidic and phosphatidic acids. In
E. coli
extracts, the relative rates of transacylation of palmityl and oleyl coenzyme A vary as a function of incubation temperature in a manner which mimics the temperature control observed in vivo. The phosphatidic acid synthesized in vitro shows a striking enrichment of oleate at the β position analogous to the positional specificity observed in phospholipids synthesized in vivo.
Fine Structure of Poly-β-Hydroxybutyric Acid Granules in a Blue-Green Alga,
Chlorogloea fritschii
Authors: Jensen Thomas E. , Sicko Linda M.
Published: January 2020

Granules characterized as poly-β-hydroxybutyric acid are described in
Chlorogloea fritschii
, a blue-green alga. They are generally spherical inclusions of slight electron density which are limited by a membrane approximately 3 nm in thickness.
Production of Phenotypically Epimeraseless Yeast by
l
-Arabinose
Authors: Azam Farooq , Kuo Shou-Chang , Cirillo Vincent P.
Published: January 2020

The previous report from this laboratory that
l
-arabinose is a gratuitous inducer of the galactose transport system has been found to be an artefact resulting from the combination of galactose contamination of commercial samples of
l
-arabinose and inhibition by
l
-arabinose of galactose metabolism by inactivation of uridine-diphosphate-glucose-4-epimerase. As a result of
l
-arabinose inhibition of the metabolism of the contaminating galactose, galactose itself serves as a gratuitous inducer, producing phenotypically epimeraseless yeast.
Changes in Hepatic Glycogen, Protein, and Ribonucleic Acid Synthesis, and Some Effects of Cortisol, During Q Fever
Authors: Stueckemann J. , Paretsky D.
Published: January 2020

Liver glycogen is depleted in guinea pigs infected with
Coxiella burneti
. Syntheses of the glycogen precursors uridine triphosphate and uridine diphosphate glucose are unaffected during Q fever, but glycogen synthetase activity is inhibited. Exogenous cortisol relieves this inhibition in infected animals. Orotate and amino acids are more rapidly incorporated into ribonucleic acid and protein during infection. It is proposed that the biochemical defect in the synthesis of glycogen lies in the inactivation of glycogen synthetase.
Microbial Life at 90 C: the Sulfur Bacteria of Boulder Spring
Authors: Brock T. D. , Brock M. L. , Bott T. L. , Edwards M. R.
Published: January 2020

The physiology of the bacteria living in Boulder Spring (Yellowstone National Park) at 90 to 93 C was studied with radioactive isotope techniques under conditions approximating natural ones. Cover slips were immersed in the spring; after a fairly even, dense coating of bacteria had developed, these cover slips were incubated with radioactive isotopes under various conditions and then counted in a gas flow or liquid scintillation counter. Uptake of labeled compounds was virtually completely inhibited by formaldehyde, hydrochloric acid, and mercuric bichloride, and inhibition was also found with streptomycin and sodium azide. The water of Boulder Spring contains about 3 μg of sulfide per ml. Uptake of labeled compounds occurs only if sulfide or another reduced sulfur compound is present during incubation. The
p
H optimum for uptake of radioactive compounds by Boulder Spring bacteria is 9.2, a value near that of the natural spring water (8.9). Many experiments with a variety of compounds were performed to determine the temperature optimum for uptake of labeled compounds. The results with all the compounds were generally similar, with broad temperature optima between 80 and 90 C, and with significant uptake in boiling (93 C) but not in superheated water (97 C). The results show that the bacteria of Boulder Spring are able to function at the temperature of their environment, although they function better at temperatures somewhat lower. The fine structure of these bacteria has been studied by allowing bacteria in the spring to colonize glass slides or Mylar strips which were immediately fixed, and the bacteria were then embedded and sectioned. The cell envelope structure of these bacteria is quite different from that of other mesophilic or thermophilic bacteria. There is a very distinct plasma membrane, but no morphologically distinct peptidoglycan layer was seen outside of the plasma membrane. Instead, a rather thick diffuse layer was seen, within which a subunit structure was often distinctly visible, and connections frequently occurred between this outer layer and the plasma membrane. The thick outer layer usually consisted of two parts, the outer part of which was sometimes missing. Within the cells, structures resembling ribosomes were seen, and regions lacking electron density which probably contained deoxyribonucleic acid were also visible.
Spore Refractility in Variants of
Bacillus cereus
Treated with Actinomycin D
Authors: Pearce Susanne M. , Fitz-James P. C.
Published: January 2020

Refractility as indicated by light microscopy, electron microscopy of thin sections, and freeze fracture etching was increased and maintained in a cortexless mutant, A(−)1, of
Bacillus cereus
var.
alesti
by the addition during sporulation stage 4 of actinomycin D, which prevents the terminal lysis of spore core associated with sporulation in this organism.
45
Calcium uptake levels and dipicolinic acid (DPA) content were similarly maintained. The location of these components appears to be in the spore protoplast. In the parent A(−), treated with actinomycin D during stage 4, spore particles with similar morphology to the mutant, that is without a cortex and with the characteristics of refractility, were obtained. A major difference in sensitivity to actinomycin D between the processes of
45
Ca uptake and DPA synthesis was observed. Some heat resistance in A(−) made cortexless by actinomycin D could be observed. These studies indicate that the role of the cortex is not to produce the dehydrated refractile spore state but to maintain it.
Comparison of the Biochemistry and Rates of Synthesis of Mesosomal and Peripheral Membranes in
Bacillus subtilis
Authors: Patch Cephas T. , Landman Otto E.
Published: January 2020

The membrane vesicle (beaded chain) portion of the mesosomes and peripheral (ghost) membrane of
Bacillus subtilis
were obtained by protoplast lysis and separated by differential and sucrose gradient centrifugation. Electron microscopy revealed that both fractions were satisfactorily homogeneous. Comparison of the two membrane preparations showed that they were similar with respect to total protein, total phosphorus, and lipid-soluble phosphorus content. Their protein patterns on acrylamide gel electrophreograms did not differ significantly. A possible point of distinction was revealed by a difference spectrum analysis of their cytochromes. The two preparations showed clear quantitative differences in all five of the enzyme activities assayed. Acrylamide gel electrophreograms of peripheral membrane stained for malate dehydrogenase showed four weak isozyme bands, whereas electrophreograms of mesosome membranes exhibited a single strong peak. (A survey of published data on enzymes in mesosome fractions shows a marked lack of correspondence between different species of bacteria.) Comparison of
3
H-acetate incorporation into the two membrane fractions showed that both were labeled at the same rate. Similarly,
35
SO
4
was taken up by both fractions at a comparable rate and was chased from both comparably. Lipid and protein labeling thus indicates that mesosome vesicle membrane is not a precursor or special growing point of peripheral membrane.
Isolation and Genetic Analysis of a Strain of
Escherichia coli
K-12 with an Amber
recA
Mutation
Authors: Mount David W.
Published: January 2020

The isolation, properties, and genetic analysis of a strain of
Escherichia coli
K-12 with an amber
recA
mutation are described. The experiments demonstrate that the
recA
product is a protein that is probably not essential for growth.
Selection of Fimbriate Transductants of
Salmonella typhimurium
Dependent on Motility
Authors: Old D. C. , Duguid J. P.
Published: January 2020

The ability to form type 1 fimbriae (Fim
+
) was readily transduced to 159 out of 161 wild-type motile Fim
−
FIRN strains of
Salmonella typhimurium
with phage P22 propagated on a Fim
+
donor strain. Fim
+
clones were isolated from about 35% of tests after the fimbriate bacteria in the transduction mixture had been enriched by culture in aerobic static broth for 48 to 96 hr. A Fim
+
transductant was isolated from only 1 out of 280 tests made with 10 nonmotile recipient FIRN strains that were nonflagellate (Fla
−
)- or possessed “paralyzed” flagella (Fla
+
Mot
−
), though motile variants from these strains were fully competent in yielding Fim
+
transductants. The property of motility was thought to facilitate the selective outgrowth of Fim
+
transductant bacteria by enabling them to migrate aerotactically to the surface of the broth where their fimbriae permitted them to float and grow in a pellicle stimulated by the free supply of atmospheric oxygen.
Citrate Cycle and Related Metabolism ofListeria monocytogenes
Authors: Trivett Terrence L. , Meyer Ernest A.
Published: January 2020

The growth response ofListeria monocytogenesstrains A4413 and 9037-7 to carbohydrates was determined in a defined medium. Neither pyruvate, acetate, citrate, isocitrate, α-ketoglutarate, succinate, fumarate, nor malate supported growth. Furthermore, inclusion of any of these carbohydrates in the growth medium with glucose did not increase the growth ofListeriaover that observed on glucose alone. Resting cell suspensions of strain A4413 oxidized pyruvate but not acetate, citrate, isocitrate, α-ketoglutarate, succinate, fumarate, or malate. Cell-free extracts of strain A4413 contained active citrate synthase, aconitate hydratase, isocitrate dehydrogenase, malate dehydrogenase, fumarate hydratase, fumarate reductase, pyruvate dehydrogenase system, and oxidases for reduced nicotinamide adenine dinucleotide and reduced nicotinamide adenine dinucleotide phosphate. The α-ketoglutarate oxidation system, succinate dehydrogenase, isocitrate lyase, and malate synthase were not detected. Cytochromes were not detected. The data suggest that strain A4413, under these conditions, utilizes a split noncyclic citrate pathway which has an oxidative portion (citrate synthase, aconitate hydratase, and isocitrate dehydrogenase) and a reductive portion (malate dehydrogenase, fumarate hydratase, and fumarate reductase). This pathway is probably important in biosynthesis but not for a net gain in energy.
Microbial Assimilation of Hydrocarbons: Phospholipid Metabolism
Authors: Makula R. A. , Finnerty W. R.
Published: January 2020

An analysis of the turnover of the major phospholipids of
Micrococcus cerificans
growing or nongrowing cultures. The turnover rates of
14
C-PE and
14
C-PE were 61.5% of the total phospholipid, exhibited no significant rate of turnover in either growing or nongrowing cultures. The turnover rates of PE-
14
C and PE-
32
P were 3.2% per hr and 1.2% per hr, respectively. Phosphatidylglycerol (PG) exhibited a turnover rate of 11% and 7.7% per hr for
14
C and
32
P, respectively, indicating an extremely slow metabolism. PG metabolism was examined in greater detail, and the data indicated a preferential 75% incorporation of glycerol-
1,3
-
14
C
into the unacylated portion of the PG molecule. The turnover of cardiolipin (CL) was extremely slow in growing cells whereas nongrowing cells exhibited a 30% and 36% increase per hr for
14
C-Cl and
14
C-CL, respectively. Glycerol-
1,3
-
14
C
was not converted to phospholipid fatty acid carbon; all radioactivity appeared only in the water-soluble backbone of the phospholipids. The kinetics of assimilation of hexadecane-
1
-
14
C
into cellular lipids is presented. Radioactivity in neutral lipid increased approximately sevenfold over the growth cycle, whereas radioactivity in phospholipid increased 50-fold during the same time period. The incorporation of radioactive fatty acids derived from the direct oxidation of hexadecane-
1
-
14
C
demonstrated differential kinetics of assimilation into PE, PG, and CL. The results indicated a rapid turnover of phospholipid fatty acids in
M. cerificans
growing at the expense of hexadecane.
NH2-Terminal Residues ofNeurospora crassaProteins
Authors: Rho Hyune Mo , DeBusk A. Gib
Published: January 2020

The NH2-terminal amino acid composition of the soluble and ribosomal proteins fromNeurospora crassamycelia and conidia was determined by the dinitrophenyl method. A nonrandom distribution of NH2-terminal amino acids was observed in the complex protein mixtures. Glycine, alanine, and serine accounted for 75% of the NH2-terminal amino acids, and glycine appeared most frequently in mature proteins of mycelia. The appearance of phenylalanine as one of the major NH2-termini in crude conidial fraction suggests that the composition of proteins may vary in different developmental stages.
Inactivation of
Escherichia coli
, F′ Episomes at Transfer, and Bacteriophage Lambda by Psoralen Plus 360-nm Light: Significance of Deoxyribonucleic Acid Cross-Links
Authors: Cole Ronald S.
Published: January 2020

We have investigated some biological consequences of light-induced psoralen-deoxyribonucleic acid (DNA) adducts and find that for several
Escherichia coli
functions (killing of strain AB2480
recA13 uvrA6
, inactivation of phage lambda plaque-forming ability in wild type and
uvrA6
hosts, loss of ability to transmit intact F
lac
+
episomes), a light exposure sufficient for production of a single cross-link per DNA molecule correlates well with the biological consequence. Although one cross-link per genome is apparently lethal to
recA13 uvr
−
strains, mutants carrying the
recA13
or
uvrA6
markers survive light exposures producing 6.7 and 16 cross-links per genome, respectively, and wild-type cells recover from 65 psoralen cross-links. Evidently, the excision and recombinational repair systems complement one another in reconstructing an intact genome from cellular DNA containing psoralen photoproducts. The above bacterial and phage strains, in which DNA repair processes are minimized, are also extremely sensitive to pyrimidine dimer-forming 254-nm UV light (without psoralen), and were expected to respond similarly to formation of psoralen-pyrimidine base monoadducts in their DNA. Since the biological inactivation by psoralen correlates well with cross-link formation, we suggest that the sensitizing action of this drug primarily derives from its ability to form DNA cross-links.
Monosaccharide and Chitin Content of Cell Walls of
Histoplasma capsulatum
and
Blastomyces dermatitidis
Authors: Domer Judith E.
Published: January 2020

Cell walls of
Histoplasma capsulatum
and
Blastomyces dermatitidis
, obtained by mechanical breakage of yeast- and mycelial-phase cultures, were lipid-extracted and then fractionated with ethylenediamine. Unextracted cell walls, lipid-extracted cell walls, and the three fractions resulting from ethylenediamine treatment were examined for monosaccharide and chitin content. The yeast-phase cell walls of five strains of
H. capsulatum
fell into two categories, designated chemotypes I and II, one of which, chemotype II, was similar to yeast-phase cell walls derived from three strains of
B. dermatitidis. H. capsulatum
chemotype I cell walls were characterized by lower content of material soluble in ethylenediamine, higher chitin content, and lower monosaccharide content than
H. capsulatum
chemotype II or
B. dermatitidis
cell walls. Approximately 80% of the monosaccharides of chemotype I cell walls was combined in forms susceptible to attack by mild acid hydrolysis, compared with about 50% of the monosaccharides of chemotype II and
B. dermatitidis. H. capsulatum
and
B. dermatitidis
yeast-phase cell walls could be distinguished, however, by their susceptibility to attack by a crude enzyme system derived from a
Streptomyces
sp. incubated with chitin as the only carbon source. Both glucose and acetylglucosamine were released from
H. capsulatum
cell walls, regardless of chemotype, during enzymatic hydrolysis, whereas only acetylglucosamine was released from
B. dermatitidis
yeast-phase cell walls. Mycelial-phase cell walls of
H. capsulatum
and
B. dermatitidis
were characterized by lower content of material soluble in ethylenediamine, higher proportions of mannose, and lower chitin content than their respective yeast phases. Glucose and acetylglucosamine were both released from all mycelial-phase cell walls, whether
H. capsulatum
or
B. dermatitidis
, by the crude enzyme system.
Bacterial Inactivation of Transforming Deoxyribonucleate
Authors: Haseltine Florence P. , Fox Maurice S.
Published: January 2020

Competent and noncompetent bacteria are able to bind deoxyribonucleate (DNA). The consequence of this binding is different for the two types of bacteria. Competent bacteria are able to utilize the DNA for transformation. DNA exposed to noncompetent bacteria loses its biological activity with a coincident reduction in the double-stranded molecular weight. The reduction in molecular weight does not appear to be sufficient to account for the loss of biological activity observed.
ColB2-K77, a Fertility-Repressed F-Like Sex Factor
Authors: Hausmann Celma , Clowes Royston C.
Published: January 2020

The colicinogenic B factor, transferred from
Escherichia coli
strain K77 (and termed ColB2-K77 or ColB2) to an
E. coli
K12 F
−
strain, is capable of promoting its own transfer to other K12 F
−
strains at a low rate (from LFC cultures) which can be increased under special conditions (HFC cultures). LFC cultures of K12 (ColB2)
+
F
−
strains show a low level of adsorption of F-specific phage particles which also increases under HFC conditions. The ColB2 factor is thus inferred to be an F-like sex factor which is repressed in its fertility. This repression is concluded to be due to a cytoplasmic repressor since, when ColB2 is present in cells containing an F factor (either autonomous or integrated), F fertility is also repressed as shown by the inability of such (ColB2)
+
F
+
[or (ColB2)
+
Hfr] strains to plaque F-specific phages, and by a reduction in the level of chromosomal transfer from such strains, compared to the corresponding F
+
(or Hfr) control strains. Mutants of the ColB2 factor in which fertility is no longer repressed (fertility derepressed or Fdr mutants) have been isolated. The ColB2Fdr mutant strains do not appear to be able to mobilize chromosomal transfer, although they have acquired F-specific phage sensitivity demonstrable by plaque formation and they transfer their colicin factor at high frequency and are well piliated. The Fdr mutation is presumed to result in the inability to synthesize the cytoplasmic fertility repressor since the ColB2Fdr factor does not repress the fertility of an F factor when present in the same host strain. A fertility-repressed drug resistance factor of the R(f) type is not stable in the presence of a ColB2 factor in the same cell and is eliminated in about 10% of the cells per generation. In contrast, another factor characteristic of the R(i) type is fully compatible with ColB2. Under conditions artificially stabilizing (ColB2Fdr)
+
(Rf)
+
strains, the enhanced fertility of ColB2Fdr is not repressed by the presence of the R factor, nor does the presence of R(f) in the intermediate strain of an HFC (for ColB2) system inhibit the normal increase in ColB2 transmissibility. It is concluded that the repressors of R(f) and ColB2, although both active on F fertility, are different; this may indicate that at least two independently repressible cistrons are involved in the expression of fertility characteristics.
Succinate as a Growth Factor for
Bacteroides melaninogenicus
Authors: Lev M. , Keudell K. C. , Milford A. F.
Published: January 2020

Rumen strains of the obligate anaerobe
Bacteroides melaninogenicus
normally require medium supplemented with both heme and vitamin K. Sodium succinate was found to be an additional growth factor in that this compound can replace the requirement for heme in the presence of vitamin K, allowing good growth of the organism, and succinate can also partially replace the requirement for vitamin K in the presence of heme. The addition of succinate to a medium supplemented with both vitamin K and heme increases the growth rate of the culture. This ability to stimulate growth was specific for succinate, and cells grown without heme but with vitamin K and succinate were insensitive to cyanide. These experiments demonstrate a central role for succinate in the metabolism of
B. melaninogenicus
.
Mutagenic Action, Loss of Transforming Activity, and Inhibition of Deoxyribonucleic Acid Template Activity In Vitro Caused by Chemical Linkage of Carcinogenic Polycyclic Hydrocarbons to Deoxyribonucleic Acid
Authors: Maher Veronica M. , Lesko Stephen A. , Straat Patricia A. , Ts'O Paul O. P.
Published: January 2020

In a solvent system of 10
−2
m
phosphate buffer (
p
H 6.8)-ethanol (2:1, v/v) and in an iodine-induced reaction, the polycyclic hydrocarbons [
3
H]3,4-benzpyrene and [
3
H]3,4-BP/[
3
H]9, 10-dimethyl-1,2-benzanthracene (DMBA) can be covalently linked to deoxyribonucleic acid (DNA) at room temperature. By stepwise addition of the hydrocarbon and repeating the reaction two to three times after isolating the hydrocarbon DNA adduct, it was possible to introduce as many as one covalently bound hydrocarbon molecule per 100 nucleotide bases. When 3,4-BP and DMBA were linked in this way to biologically active transforming DNA of
Bacillus subtilis
, they caused (i) reduction of the transforming activity of the DNA accompanied by (ii) significant increases in the frequency of forward mutations. The majority of these hydrocarbon-induced mutations were not able to revert spontaneously. These samples of DNA covalently linked with hydrocarbons showed much lower levels of survival of biological activity when assayed in recipient strains (
hcr
−
) which are known to be deficient in the enzymes required for repair of ultraviolet light-induced damage to DNA. 3,4-BP covalently linked to calf thymus DNA at a level of approximately one hydrocarbon molecule per 330 bases was shown to cause up to 80% inhibition of the in vitro transcription of the DNA by highly purified ribonucleic acid polymerase prepared from
Micrococcus luteus
under the experimental condition of template saturation. The presence of 3,4-BP and DMBA molecules covalently bound to
B. subtilis
DNA samples was also found to prevent complete denaturation of the bihelical structure of certain DNA molecules and thus appears to effect a cross-link in these DNA molecules.
Gas-Vacuolated Strains of
Microcyclus aquaticus
Authors: Van Ert M. , Staley J. T.
Published: January 2020

Two strains of gas-vacuolated heterotrophic bacteria have been isolated from freshwaters by using 0.01% peptone enrichments. Both are nonmotile, vibrioid organisms that form rings before division. In terms of these morphological traits and other characteristics, including nutritional characters and deoxyribonucleic acid base composition, these new isolates are very similar to
Microcyclus aquaticus
. It is proposed that they be considered strains of this species.
Altered Deoxyribonucleic Acid Polymerase Activity in a Methyl Methanesulfonate-Sensitive Mutant of
Bacillus subtilis
Authors: Gass Kenneth B. , Hill Thomas C. , Goulian Mehran , Strauss Bernard S. , Cozzarelli Nicholas R.
Published: January 2020

Of six deoxyribonucleic acid repair mutants of
Bacillus subtilis
assayed for deoxyribonucleic acid polymerase, only the methyl methanesulfonate-sensitive and ultraviolet light-sensitive mutant JB1-49(59) has impaired polymerase activity. Extracts prepared by sonic treatment or gentle lysis had about 10% of the wild-type activity with poly d(A–T), an alternating copolymer of deoxyadenylate and deoxythymidylate, used as template. The sensitivity to methyl methanesulfonate and ultraviolet light and the low level of polymerase activity transformed and reverted together, indicating that the two characteristics are a pleiotropic manifestation of a single mutation. Mixed extract and kinetic experiments mitigated against an altered nuclease activity as the enzymatic consequence of the mutation. Also, the mutant and wild type activities were stimulated equally by
Escherichia coli
exonuclease III. The residual activity in the mutant showed several differences from the wild-type activity: it purified differently, was more sensitive to sulfhydryl reagents, and displayed a different template specificity. We tentatively conclude that either the mutation in JB1-49(59) has introduced a qualitative as well as a quantitative change in the polymerase or the wild type contains two distinct polymerases, one of which is missing in the mutant.
Transfer Ribonucleic Acid Methylases During the Germination of
Neurospora crassa
Authors: Wong Rosemary S. L. , Scarborough Gene A. , Borek Ernest
Published: January 2020

Transfer ribonucleic acid (tRNA) methylases were studied during the germination of spores in
Neurospora crassa
. The total methylase capacity and base specific tRNA methylase activities were determined in extracts from cells harvested at various stages of germination. Germinated conidia have a 65% higher methylase capacity than ungerminated conidia. Three predominant methylase activities were found in the extracts, and the relative amount of each activity was different at the various stages. Enzymes from vegetative cells catalyzed significant hypermethylation of tRNA from conidia, whereas conidial enzymes were much less active on tRNA from vegetative cells. The results indicate differences in the tRNA methylase content and tRNA species of conidia and vegetative cells.
Mapping the Gene Determining Ornithine Transcarbamylase and Its Operator in
Escherichia coli
B
Authors: Jacoby George A.
Published: January 2020

The gene determining ornithine transcarbamylase in
Escherichia coli
B is
argI
, not
argF
. The
argI
gene has been located at 84 min on the linkage map, close to the gene for aspartate transcarbamylase, with neighboring markers in clockwise order
fdp pyrB argI valS
. A mutation in its operator locus,
argO
I
, has been mapped between
argI
and
valS
, so that this gene, unlike the
argCBH
portion of the
argECBH
cluster, appears to be oriented in the same direction as most of the other known
E. coli
operons.
Effect of Hydroxylysine on the Biosynthesis of Lysine in
Saccharomyces
Authors: Sinha Asru K. , Kurtz Mark , Bhattacharjee Jnanendra K.
Published: January 2020

Hydroxylysine acts as a growth inhibitor of
Saccharomyces
for a certain period of time. The inhibition is concentration-dependent and is reversed by a small amount of lysine in the medium. After the growth-inhibitory period, the wild-type cells are able to grow rapidly even in the presence of hydroxylysine. Both lysine auxotrophs and wild-type cells are unable to utilize hydroxylysine in place of lysine. Hydroxylysine, mimicking lysine, controls the biosynthesis of lysine and thereby limits the availability of biosynthetic lysine to the cells. Hydroxylysine affects the biosynthesis of lysine at a number of enzymatic steps. Accumulation of homocitric acid, the first intermediate of lysine biosynthesis, in the mutant strains 19B and A B9 is reduced significantly in the presence of hydroxylysine. Hydroxylysine, like lysine, exerts a significant inhibition in vitro on the homocitric acid-synthesizing activity. Enzymes following the α-aminoadipic acid step respond in a noncoordinate fashion to hydroxylysine. Level of the enzyme saccharopine reductase, but not of α-aminoadipic acid reductase or saccharopine dehydrogenase, is reduced significantly. These regulatory effects of hydroxylysine are similar to those observed for lysine.
Purification and Characterization of the L Component of
Streptococcus zymogenes
Lysin
Authors: Granato Paul A. , Jackson Robert W.
Published: January 2020

By utilizing conventional techniques of pressure ultrafiltration, gel filtration chromatography, diethylaminoethyl cellulose chromatography, and preparative polyacrylamide electrophoresis, the L component of the group D lysin produced by
Streptococcus zymogenes
strains has been purified to a state of homogeneity as determined by the techniques of disc-gel electrophoresis at
p
H 9.3 and 4.3 and isoelectric focusing. The L component was found to be a protein possessing a molecular weight of 11,000 with a slight net negative charge at physiological
p
H.