bluuebunny/crossref_metadata_2025 huggingface dataset:
Isolation and Mapping of Polynucleotide Phosphorylase Mutants of
Escherichia coli
Authors: Reiner Albey M.
Published: January 2020

Three strains of
Escherichia coli
with altered polynucleotide phosphorylase, Q7, Q13, and Q27, were isolated by screening clones from heavily mutagenized cultures for low levels of the enzyme. The three mutations were found to cotransduce with
argG
and
asp
, and the
pnp
locus which they define was mapped with respect to these loci. An explanation for the nonreciprocal cotransduction frequencies observed with
asp
is provided by the demonstration of an unlinked
asp
-suppressing locus.
Gene-Enzyme Relationships in Histidine Biosynthesis in
Bacillus subtilis
Authors: Chapman Linda F. , Nester Eugene W.
Published: January 2020

Mutants for 9 of the 10 steps in histidine biosynthesis have been isolated and identified by enzyme assay. Each locus has been mapped in relation to the
aro
cluster and to other histidine loci by deoxyribonucleic acid-mediated transformation. The genes which code for enzymes 3, 6, and 8 of the pathway are linked to the
aro
cluster. A major histidine linkage group is composed of the genes which specify enzymes 1, 2, 5, 7, and 10. The locus which codes for step 9 of the pathway is unlinked to any other identified
his
loci. The major histidine cluster is loosely linked to
cysB
and is unlinked to any of the loci concerned with aromatic amino acid biosynthesis.
Electron Microscopic Study of Membranes and Walls of Bacteria and Changes Occurring During Growth Initiation
Authors: Hurst A. , Stubbs J. M.
Published: January 2020

Thin sections of stationary-phase
Streptococcus lactis
cells showed that the wall and membrane are 20 and 7 nm thick, respectively. Whole cells were examined by negative staining with ammonium molybdate and by shadowing. On air-drying of whole cells, the membrane pulled away from the wall revealing adhesions between these organelles. Adhesions could not be seen after subculture of the stationary-phase cells into complex media or into solutions containing glucose, KCl, and CaCl
2
in tris(hydroxymethyl)aminomethane buffer. The adhesions were also observed in stationary-phase cells of other gram-positive bacteria. Fractured freeze-etched cells of
S. lactis
had a smooth outside surface, but the inside of the wall (or outside of the membrane) had a regular structure, repeating at 10 nm, which could correspond to the adhesions observed in the negatively stained air-dried cells. Freeze-etching also revealed holes in the outside wall which had the shape of inverted truncated cones. The outside diameter of the cone was 60 nm, and the diameter on the inside surface of the wall was 20 nm. The membrane had upstanding plugs, 20 nm in diameter, which could fill the holes in the wall.
Cell Wall and Coat of the Developing Akinete of a
Cylindrospermum
Species
Authors: Jensen Thomas E. , Clark Robert L.
Published: January 2020

The mature akinete coat of a
Cylindrospermum
species contains laminar layers, not present in immature akinetes, and a thickened intermediate layer.
Antimetabolite Action of 5-Methyltryptophan in
Bacillus subtilis
Authors: Jensen Roy A.
Published: January 2020

The roles of anthranilate and histidine in the regulation of tryptophan synthesis were implicated by observations of antagonistic relationships with 5-methyltryptophan in
Bacillus subtilis
.
Sporulation of
Clostridium thermosaccharolyticum
Under Conditions of Restricted Growth
Authors: Hsu Edward J. , Ordal Z. John
Published: January 2020

Glucose served as an exogenous energy source for sporulation when a limited amount was fed continuously. Excess glucose repressed sporulation.
Antibiotic Inhibition of the Septation Stage in Sporulation of
Bacillus megaterium
Authors: Hitchins Anthony D. , Slepecky Ralph A.
Published: January 2020

The inhibition of sporulation septation (stage II) in
Bacillus megaterium
was shown with penicillin,
d
-cycloserine, bacitracin, vancomycin, novobiocin, chloromycetin, streptomycin, mitomycin C, and nalidixic acid.
Ribosome Synthesis in
Rhodopseudomonas capsulata
Cells Growing In Continuous and Intermittent Light
Authors: Din George A. , Gest Howard
Published: January 2020

The ribosome content was markedly reduced when illumination (at 28 C) was repeatedly interrupted; an opposite trend was observed with continuous light as the temperature was decreased.
Separation and Identification of the Polar Lipids of
Chromatium
Strain D
Authors: Steiner S. , Conti S. F. , Lester R. L.
Published: January 2020

The polar lipids of the autotrophically grown, obligately anaerobic, photosynthetic bacterium
Chromatium
strain D were separated by paper chromatography. Four major phospholipids were identified: lysophosphatidylethanolamine, phosphatidylethanolamine, phosphatidylglycerol, and cardiolipin. In addition, three glycolipids were observed and characterized, namely, monoglucosyldiglyceride, which is found in other biological systems, and (mannosyl, glucosyl)-diglyceride and (dimannosyl, glucosyl)-diglyceride, which heretofore have not been observed in nature.
Phospholipids of
Nocardia coeliaca
Authors: Yano Ikuya , Furukawa Yoshiya , Kusunose Masamichi
Published: January 2020

The lipids of
Nocardia coeliaca
were separated into at least 10 components by the use of thin-layer chromatography. Phosphatidylcholine was the most abundant phospholipid in this organism, accounting for 25 to 40% of the total phospholipids. The major fatty acid components of the phosphatidylcholine were 14-methyl-pentadecanoic acid (41%), the other C
15
and C
17
iso- and anteiso-fatty acids (29%), and palmitic acid (13.5%). The next most abundant phospholipid was phosphatidylethanolamine (25 to 30%), followed by phosphatidylinositol (11 to 14%) and cardiolipin (7 to 15%). Phosphatidylethanolamine and phosphatidylinositol were very similar to the phosphatidylcholine in fatty acid composition, whereas cardiolipin was characterized by a higher content of palmitic acid (30%). In all of the phospholipids examined, only trace amounts of monounsaturated fatty acids were present. When washed cells of
N. coeliaca
were incubated with methionine-methyl-
14
C for 1 to 3 hr, the radioactivity was mainly incorporated into the choline moiety of the phosphatidylcholine. In contrast, acetate-
1
-
14
C
or glycerol-
1
-
14
C
was incorporated much more slowly into the phosphatidylcholine than into the other phospholipids and neutral lipids. No phosphatidylcholine was detected in 10 other species of
Nocardia
examined.
Phenotypic Suppression in
Escherichia coli
by Chloramphenicol and Other Reversible Inhibitors of the Ribosome
Authors: Kirschmann Chava , Davis Bernard D.
Published: January 2020

Antibiotics that interfere reversibly with various aspects of ribosomal function (chloramphenicol, tetracycline, erythromycin, and spectinomycin) are shown to antagonize, at barely inhibitory concentrations, the inhibitory effect of low concentrations of streptomycin (SM) on the growth of
Escherichia coli
. Paradoxically, these compounds can also replace SM in supporting the growth of conditionally SM-dependent mutants. Chloramphenicol produced about as much phenotypic suppression as SM in SM-sensitive strains, but less than that attainable with high concentrations of SM in resistant strains. The antagonism to SM inhibition and the phenotypic suppression appear to be specific for those growth inhibitors that act on the ribosome. Since inhibitors of the 50
S
subunit of the ribosome (chloramphenicol, erythromycin) are as active as inhibitors of the 30
S
subunit, it is suggested that phenotypic suppression by borderline concentrations of ribosome inhibitors does not necessarily depend on an alteration of the recognition region of the ribosome. Alternatively, partial inhibition of the ribosomes might change the environment in a way that would influence the frequency of misreading. Phenotypic suppression by a low concentration of SM as well as by chloramphenicol was found to depend on the presence of a trace of the required growth factor.
Energy Coupling in the Transport of β-Galactosides by
Escherichia Coli:
Effect of Proton Conductors
Authors: Pavlasova Emilie , Harold F. M.
Published: January 2020

Escherichia coli
accumulates thiomethyl-β-
d
-galactoside against a concentration gradient under anaerobic conditions. The accumulation was abolished by carbonylcyanide
m
-chlorophenylhydrazone, tetrachlorosalicylanilide, 2,4 dinitrophenol, and other uncouplers of oxidative phosphorylation even though oxidative phosphorylation would not be expected to occur anaerobically. In the presence of the uncouplers, the β-galactoside carrier remained functional and catalyzed equilibration of thiomethylgalactoside across the membrane. The uncouplers did not inhibit the generation of adenosine triphosphate or protein turnover, or the accumulation of α-methylglucoside and glycerol by phosphorylation. We conclude that, at least anaerobically, uncouplers of oxidative phosphorylation do not interfere with energy metabolism in general, but prevent the utilization of metabolic energy for the active transport of galactosides. The uncouplers also facilitate passage of protons across the membrane. Various hypotheses are considered to explain why a proton-impermeable membrane may be required for active transport of galactosides and other substrates.
Cell Wall Growth During Differentiation of
Proteus
Swarmers
Authors: Hoeniger Judith F. M. , Cinits Edward A.
Published: January 2020

This paper describes the process by which the cell wall of
Proteus mirabilis
, as measured by the presence of the O antigen, develops during the differentiation of swarmers from short cells on an agar surface. The sequence was followed by fluorescent-antibody staining, with both the direct and reverse methods. When the organisms were labeled with fluorescent antibody by the direct method, they showed a progressive diminution of the marker along the cell surface and some increase in the length of the bacteria. However, the label had become completely diluted out before typical swarmers developed. When the bacteria were exposed initially to unlabeled antibody by the reverse technique, and then incubated with fluorescent antibody, they showed a progressive increase both in the intensity of the label along their entire periphery and in cellular length, culminating in the formation of swarmers. It is concluded that in
P. mirabilis
, as in the few other gram-negative bacteria examined so far, cell wall synthesis takes place diffusely, i.e., by intercalation of new with old components along the length of the cell wall.
Effects of Some Antitumor Agents on Growth and Glycolytic Enzymes of the Flagellate
Crithidia
Authors: Bacchi Cyrus J. , Ciaccio Edward I. , Koren Lois E.
Published: January 2020

Some antitumor agents known to specifically inhibit certain tumor cell enzymes were examined for activity against glycolytic enzymes and growth of the insect trypanosomatid,
Crithidia fasciculata
. The cytoplasmic enzymes hexokinase, α-glycerophosphate dehydrogenase, malic dehydrogenase, and glucose-6-phosphate dehydrogenase were tested. Agaricic acid (2-hydroxy-1,2,3-nonadecane tricarboxylic acid) was highly inhibitory (50 to 100%) to malic and α-glycerophosphate dehydrogenases at ∼3 × 10
−5
m
; 2-(
p
-hydroxyphenyl)-2-phenylpropane (2 × 10
−4
m
), and 5,6-dichloro-2-benzoxazolinone (5 × 10
−4
m
) were less effective (50% inhibition) against them. The antiprotozoal agents primaquine (4 × 10
−4
m
) and Melarsoprol (8 × 10
−4
m
) were 30 to 40% inhibitory. Agaricic acid, 2-(
p
-hydroxyphenyl)-2-phenylpropane, and 5,6-dichloro-2-benzoxazolinone inhibited growth of
Crithidia
at less than 10
−4
m
. Eight other test compounds from the Cancer Chemotherapy National Service Center (CCNSC) were not toxic to cell growth, although two (4-biphenylcarboxylic acid and 1-[
p
-chlorobenzyl]-2-ethyl-5-methyl-indole-3-acetic acid) inhibited
Crithidia
α-glycerophosphate dehydrogenase below 1 m
m
. All of the compounds used specifically inhibited cancer cell α-glycerophosphate dehydrogenase. The corresponding enzyme in pathogenic African trypanosomes is important in their terminal respiration.
C. fasciculata
may be useful in preliminary evaluation of chemotherapeutic agents as potential trypanocides.
Characterization of Ribosomes from the Myxomycete
Physarum rigidum
Grown in Pure Culture
Authors: Henney Henry R. , Jungkind Donald
Published: January 2020

The plasmodial phase of the myxomycete
Physarum rigidum
, analyzed during the period of rapid growth, attained a ribonucleic acid (RNA) and protein content of 9.8 and 60.0%, respectively, on a dry weight basis. It possessed ribosomes of the 80
S
class which, especially in the absence of magnesium ions, partially dissociated to 60
S
and 40
S
subunit classes. Electron micrographs of ribosomes treated with uranyl acetate-lead citrate revealed a number of surface features. Nucleotide analyses of both ribosomal and total RNA disclosed that they were composed of 51.0 and 52.5% guanylic and cytidylic acids, respectively. Consistent with most reports on other organisms, guanylic acid was the most abundant nucleotide found in the various types of RNA and cytidylic acid was the least abundant. The
S
0
20,w
values of the total RNA classes, in 0.01 sodium acetate (
p
H 4.6) containing 0.10
m
NaCl, were 5.2, 18.1, and 27.3 in
S
units. Changing the ionic environment of the RNA (0.017 molal potassium phosphate,
p
H 7.0, containing 0.01
m
disodium ethylenediaminetetraacetate) resulted in a reduction of the
S
0
20,w
values to 4.2, 16.6, and 22.6 in
S
units, which is indicative of molecular conformational transitions. In general, the amino acid composition of the ribosomal proteins was similar to the data available on ribosomal proteins from other biological sources.
Thermus aquaticus
gen. n. and sp. n., a Nonsporulating Extreme Thermophile
Authors: Brock Thomas D. , Freeze Hudson
Published: January 2020

The isolation of a new thermophilic bacterium,
Thermus aquaticus
gen. n. and sp. n., is described. Successful enrichment requires incubation at 70 to 75 C, and the use of nutrient media relatively dilute with respect to the organic components. Strains of
T. aquaticus
have been isolated from a variety of thermal springs in Yellowstone National Park and from a thermal spring in California. The organism has also been isolated from man-made thermal habitats, such as hot tap water, in geographical locations quite distant from thermal springs. Isolates of
T. aquaticus
are gram-negative nonsporulating nonmotile rods which frequently form long filaments at supraoptimal temperatures or in the stationary phase. All isolates form a yellow cellular pigment, probably a carotenoid. A characteristic structure formed by all isolates is a large sphere, considerably larger than a spheroplast. These large spheres, as well as lysozyme-induced spheroplasts, are resistant to osmotic lysis. Deoxyribonucleic acid base compositions of four strains were determined by CsCl density gradient ultracentrifugation and found to be between 65.4 and 67.4 moles per cent guanine plus cytosine. The growth of all isolates tested is inhibited by fairly low concentrations of cycloserine, streptomycin, penicillin, novobiocin, tetracycline, and chloramphenicol. Nutritional studies on one strain showed that it did not require vitamins or amino acids, although growth was considerably faster in enriched than in synthetic medium. Several sugars and organic acids served as carbon sources, and either NH
4
+
or glutamate could serve as nitrogen source. The organism is an obligate aerobe and has a
p
H optimum of 7.5 to 7.8. The optimum temperature for growth is 70 C, the maximum 79 C, and the minimum about 40 C. The generation time at the optimum is about 50 min. The possible relationships of this new genus to the myxobacteria, flexibacteria, and flavobacteria are discussed.
Presence of Nuclear Bodies in Some Minicells of
Escherichia coli
Authors: Tudor J. , Hashimoto T. , Conti S. F.
Published: January 2020

Electron microscopy of serial sections of
Escherichia coli
K-12 (P678-54) revealed that some “minicells” contain nuclear bodies.
New Hemolysin (γ) Produced by
Escherichia coli
Authors: Walton John R. , Smith David H.
Published: January 2020

A new hemolysin (γ) of
Escherichia coli
, active in the absence of viable bacteria, has been recognized in mutants resistant to nalidixic acid. Nalidixic acid affects either the production or release of the hemolysin.
Physical Behavior of Pneumolysin
Authors: Kreger Arnold S. , Bernheimer Alan W.
Published: January 2020

Pneumolysin behaved as an acidic protein having an isoelectricpH of 4.9, a molecular weight of approximately 63,000, and a sedimentation coefficient of approximately 4.3.
Degradation of α-Ketoglutarate by
Veillonella alcalescens
Authors: Lindley Renda Wong , Delwiche E. A.
Published: January 2020

Veillonella alcalescens
degrades α-ketoglutarate to CO
2
, H
2
, and propionate by a thioclastic mechanism.
Effect of Penicillin on
Staphylococcus aureus
Cultivated at High Atmospheric Pressure
Authors: Schlamm N. A. , Coykendall A. L. , Meyers C. E.
Published: January 2020

Staphylococcus aureus
showed decreased penicillin susceptibility at high atmospheric pressure (0.3% O
2
in He, 1,000 psi). High pressure may have protected the bacteria by osmotic stabilization.
Characterization of a Newly Identified Mycoplasma (Mycoplasma oraleType 3) from the Human Oropharynx
Authors: Fox H. , Purcell R. H. , Chanock R. M.
Published: January 2020

Six mycoplasma strains, isolated under anaerobic conditions from the human oropharynx, were studied by biologic and serologic means. The strains produced nippled colonies with weak hemolytic activity for guinea pig erythrocytes on agar medium. In addition, the strains metabolized arginine with a concomitant alkaline shift in thepH of the medium but did not produce apH shift when grown in the presence of glucose or urea. The strains failed to reduce 2–3–5 triphenyl tetrazolium and were inhibited by 0.001% methylene blue. In addition, they required fresh yeast extract for growth. When compared by several serologic methods, the strains were found to be related to each other but distinct from 23 serotypes of human, animal, and avian origin. However, one-way serologic relationships between one of the new strains andMycoplasma oraletype 1 andM. salivariumwere observed when they were tested by complement fixation. Furthermore, partial relationship of one of the new strains to all of the arginine-utilizing mycoplasma species of human origin was demonstrated with the agar gel diffusion technique. Thus, the new strains appear to constitute a new mycoplasma species, for which the nameM. oraletype 3 is tentatively proposed.M. oraletype 3 accounted for 1.4% of 437 mycoplasma isolates from the oropharynx of adults. The new species probably is a rare member of the normal mycoplasmal flora of man.
Regulated Enzymes of Aromatic Amino Acid Synthesis: Control, Isozymic Nature, and Aggregation in
Bacillus subtilis
and
Bacillus licheniformis
Authors: Nasser Delill , Henderson Gary , Nester Eugene W.
Published: January 2020

Several regulated enzymes involved in aromatic amino acid synthesis were studied in
Bacillus subtilis
and
B. licheniformis
with reference to organization and control mechanisms.
B. subtilis
has been previously shown (23) to have a single 3-deoxy-
d
-
arabino
heptulosonate 7-phosphate (DAHP) synthetase but to have two isozymic forms of both chorismate mutase and shikimate kinase. Extracts of
B. licheniformis
chromatographed on diethylaminoethyl (DEAE) cellulose indicated a single DAHP synthetase and two isozymic forms of chorismate mutase, but only a single shikimate kinase activity. The evidence for isozymes has been supported by the inability to find strains mutant in these activities, although strains mutant for the other activities were readily obtained. DAHP synthetase, one of the isozymes of chorismate mutase, and one of the isozymes of shikimate kinase were found in a single complex in
B. subtilis
. No such complex could be detected in
B. licheniformis
. DAHP synthetase and shikimate kinase from
B. subtilis
were feedback-inhibited by chorismate and prephenate. DAHP synthetase from
B. licheniformis
was also feedback-inhibited by these two intermediates, but shikimate kinase was inhibited only by chorismate. When the cells were grown in limiting tyrosine, the DAHP synthetase, chorismate mutase, and shikimate kinase activities of
B. subtilis
were derepressed in parallel, but only DAHP synthetase and chorismate mutase were derepressible in
B. licheniformis
. Implications of the differences as well as the similarities between the control and the pattern of enzyme aggregation in the two related species of bacilli were discussed.
Biochemical Studies of Bacterial Sporulation and Germination XIV. Phospholipids in
Bacillus megaterium
Authors: Bertsch LeRoy L. , Bonsen Pieter P. M. , Kornberg Arthur
Published: January 2020

The principal phospholipids of
Bacillus megaterium
throughout the cycle of growth and sporulation were found to be phosphatidylglycerol, diphosphatidylglycerol, phosphatidylethanolamine, and a hitherto unidentified isomer of glycosaminyl-phosphatidylglycerol. Phosphatidylglycerol predominated during vegetative cell growth and then declined as spores developed, whereas diphosphatidylglycerol became more prominent during spore maturation. The latter phosphatide was relatively inaccessible in the vegetative cell and was more accessible in the spore, as judged by solvent extraction under various conditions.
Susceptibility to Polymyxin B of Penicillin G-induced
Proteus mirabilis
L Forms and Spheroplasts
Authors: Teuber Michael
Published: January 2020

A polymyxin B-resistant strain of
Proteus mirabilis
was converted into L forms and spheroplasts in the presence of penicillin G. This treatment caused a 400-fold increase in polymyxin B susceptibility. The acquired susceptibility was in the range of the natural susceptibility reported for susceptible gram-negative bacteria (∼1 μg/ml). The high susceptibility to polymyxin B was lost as soon as the spheroplasts and L forms were allowed to reconvert into the bacillary form in penicillin-free media. This behavior is strong evidence that the natural resistance of
Proteus
strains to polymyxins is due to the impermeability of the outer cell wall structures to these antibiotic substances.
Plaque Assay for
Rickettsia rickettsii
Authors: Weinberg Edmund H. , Stakebake Jack R. , Gerone Peter J.
Published: January 2020

A plaque technique for the assay of
Rickettsia rickettsii
is described. The method employs primary chick or green monkey kidney monolayer cell cultures with either an agarose or special Noble agar overlay. Plaques were counted in 6 days and resultant titers correlated well with
ld
50
end points obtained by a standard assay in embryonated eggs. Identification of the plaque-forming organisms was accomplished by direct observation of rickettsiae-like bodies in the monolayer lesions, inhibition of plaques by antibiotics, sensitivity of plaques to specific immune serum, and failure to cultivate other microorganisms from the infected cells. Versatility of the test was demonstrated by assaying samples of rickettsiae from several different sources commonly used in our laboratory. These included infected yolk sacs, various cell cultures, and infected guinea pig tissue. Sufficient numbers of viable rickettsiae were present in the cells of a single lesion to permit direct recovery.
Serological Studies ofClostridium botulinumType E and Related Organisms II. Serology of Spores
Authors: Solomon H. M. , Lynt R. K. , Kautter D. A. , Lilly T.
Published: January 2020

Pure spore antigens for the immunization of rabbits were prepared by enzymic digestion of vegetative components and separation of the cleaned spores in polyethylene glycol. Spore antisera were prepared to strains representative of toxigenicClostridium botulinumtype E; nontoxigenic boticin E-producing variants; nontoxigenic nonproducers of boticin E; nontoxigenic “atypical” strains, which differ somewhat fromC. botulinumtype E in their physiology;C. botulinumtypes A and B; andC. bifermentans. They were tested against these and additional strains representative of the above groups, other types ofC. botulinum, and otherClostridiumspecies. There was no evidence of agglutination of flagellar or somatic antigens of vegetative cells by these antisera. Agglutination and agglutinin absorption tests showed common antigens among toxigenic type E strains and nontoxigenic variants, both producers and nonproducers of boticin E. Some nontoxigenic “atypical” strains varied in their ability to be agglutinated by type E antisera, and others did not agglutinate at all. Of those atypical strains that were not agglutinated, one was agglutinated byC. bifermentansantiserum. Antisera prepared againstC. botulinumtypes A and B andC. bifermentansdid not agglutinate the spores of type E or its variants nor share antigens common to each other. Similarly, antisera to type E, its nontoxigenic variants, and nontoxigenic atypical strains did not agglutinate otherC. botulinumtypes or any otherClostridiumspecies investigated.
Fatty Acid Desaturase Mutants of
Saccharomyces cerevisiae
Authors: Keith A. D. , Resnick M. R. , Haley A. B.
Published: January 2020

Genetic and biochemical analyses were conducted on fatty acid mutants of yeast deficient for Δ
9
-desaturase activity in the production of palmitoleate and oleate. Two genetic loci were observed and two others are inferred; three of these were represented by respiratory-deficient (petite) strains. All strains were incapable of converting palmitate to palmitoleate and stearate to oleate whether the direct precursor or acetate was followed. All strains were capable of acylating both de novoproduced fatty acids and oleate taken up from the medium into phospholipids and neutral lipids. Two revertants were analyzed which differed in their ability to produce palmitoleate and oleate.
Thiosulfate Reductase Isolated from
Desulfotomaculum nigrificans
Authors: Nakatsukasa Walter , Akagi J. M.
Published: January 2020

A thiosulfate reductase from
Desulfotomaculum nigrificans
has been partially purified by ammonium sulfate fractionation, diethylaminoethylcellulose chromatography, and sucrose density gradient centrifugation. With inner-and outer-labeled
35
S-thiosulfate, the enzyme reduced only the outer sulfur atom to hydrogen sulfide. The enzyme was inhibited by sulfite and also by several sulfhydryl inhibitors. The
K
m
value for this enzyme was calculated to be 1.3 × 10
−1
m
. Other inorganic sulfur compounds, such as sulfate, sulfite, tetrathionate, and dithionate, were not reduced by this enzyme.
Endotoxin-free Biologically Active Component of
Escherichia coli
Authors: Rosselet J. P. , Murphy S. G. , Adamski R. J. , Fletcher M. J. , Ludwig B. J.
Published: January 2020

The proteinaceous component of gram-negative bacteria, which has been termed “protodyne,” enhances nonspecific host resistance while eliciting a slight pyrogenic response equivalent to 0.2% that of a typical endotoxin. Since this material still contains small amounts of carbohydrate and lipid, it was imperative to establish that its biological activities are not the result of endotoxin contamination. Evidence that the protective activity of protodyne does not result from endotoxin contamination has now been obtained by an evaluation of the Pronase digestion products of this substance. These digestion products were found to be nonpyrogenic and to contain no measurable amount of 2-keto-3-deoxyoctonate, an essential component of bacterial lipopolysaccharides.
Sensitivity ofPseudomonas aeruginosato Normal Serum and to Polymyxin
Authors: Muschel Louis H. , Ahl Lissa A. , Fisher M. W.
Published: January 2020

Strains ofPseudomonas aeruginosaisolated from clinical material were very variable in their sensitivity to the bactericidal action of normal serum mediated by the complement system. Fifty per cent killing end points ranged from 0.015 ml to greater than 0.4 ml. Most of the strains with relatively greater sensitivity to serum were isolated from patients with cystic fibrosis. Immunization of rabbits resulted in antisera with enhanced levels of bactericidal antibody, except with one strain which was resistant to the bactericidal action of normal serum and antiserum. WhenP. aeruginosawas cultivated at 41 C instead of at 37 C, it was significantly more sensitive to serum and to several antibiotics, thereby implicating fever as a host defense mechanism inPseudomonasinfections. In contrast to their heterogeneity to serum bactericidal activity, the strains were relatively homogeneous in their sensitivity to polymyxin, with no apparent association between their sensitivity to the two antimicrobial agents.
Macromolecular Synthesis in
Saccharomyces cerevisiae
in Different Growth Media
Authors: Wehr C. T. , Parks L. W.
Published: January 2020

Synthesis of ribonucleic acid (RNA), deoxyribonucleic acid (DNA), and protein was determined in
Saccharomyces cerevisiae
during amino acid and pyrimidine starvation and during shift-up and shift-down conditions. During amino acid starvation, cell mass, cell number, and RNA continued to increase for varying periods. During amino acid and pyrimidine starvation, cell mass and RNA showed little increase, whereas total DNA increased 11 to 17%. After a shift from broth medium to a minimal defined medium, increase in RNA and protein remained at the preshift rate before assuming a lower rate. DNA increase remained at an intermediate rate during shift-down, and then dropped to a low rate. During shift-up from minimal to broth medium, increase in cell number, protein, and DNA showed varying lag periods before increasing to the new rate characteristic of broth medium; each of these quantities exhibited a step sometime in the first 2 hr after transfer to rich medium, suggesting a partial synchronous division. Immediately after shift-up, RNA synthesis assumed a high rate, and then dropped to a rate characteristic of growth in the rich medium after about 1 hr.
Plaque Formation in Chick Embryo Fibroblast Cells by
Chlamydia
Isolated From Avian and Mammalian Sources
Authors: Piraino F.
Published: January 2020

Fifteen strains of chlamydial agents, 2
Chlamydia trachomatis
and 13
Chlamydia psittaci
, were tested for plaque formation on chick embryo fibroblast cells.
C. trachomatis
strains did not form plaques; 12 strains of
C. psittaci
did form plaques and 1 strain did not. The distribution of plaque sizes with
C. psittaci
strains was studied and it was found that the 12 strains could be tentatively grouped into three plaquing types: small (<0.50 mm), intermediate (0.50 to 0.90 mm), and large (>0.90 mm). Small plaques were predominantly associated with strains M56, ET, CP3, CT4, EBA, CS1, and CT2. Intermediate size plaques were predominantly associated with strains NJ1, VT1, and H81. Large plaques were predominantly associated with strains WC and OG. Plaque size appears to be related to virulence of
Chlamydia
for laboratory animals.
Fatty Acids and Polar Lipids of Extremely Thermophilic Filamentous Bacterial Masses from Two Yellowstone Hot Springs
Authors: Bauman A. J. , Simmonds Peter G.
Published: January 2020

The fatty acid composition of filamentous bacterial masses from two very hot Yellowstone Park springs is not unusual despite the extreme environment. Both populations have a series of C
14
to C
20
straight-chain acids with a maximum at C
18
, and a series of saturated iso acids with a maximum at C
17
in one case and C
19
in the other. The fatty acid pattern of this anomalous group of organisms is like that of bacteria but not of blue-green algae. Both populations have similar polar lipids and identical carotenoids. It is speculated that these organisms may be adapted to their high-temperature environment by means of stable lipoprotein membrane systems.
Genetic Control of Phosphoglucomutase Variants in
Saccharomyces cerevisiae
Authors: Bevan Patricia , Douglas Howard C.
Published: January 2020

The three electrophoretic variants of phosphoglucomutase in
Saccharomyces cerevisiae
breeding stocks are produced by two unlinked genes,
pgm-1
and
pgm-2; pgm-1
contains two known alleles,
pgm-1a
and
pgm-1b
, each of which specifies a minor phosphoglucomutase component, and
pgm-2
specifies the major phosphoglucomutase component.
Alteration in the Amino Acid Content of Yeast During Growth Under Various Nutritional Conditions
Authors: Moat Albert G. , Ahmad Fazal , Alexander James K. , Barnes Isabel J.
Published: January 2020

Yeast cells grown under optimal and suboptimal concentrations of biotin were analyzed for the amino acid content of their soluble pool and cellular protein. Optimally grown yeast cells exhibited a maximum amino acid content after 18 hr of growth. Biotin-deficient cells were depleted of all amino acids at 26 and 43 hr, with alanine, arginine, aspartate, cysteine, glutamate, isoleucine, leucine, lysine, methionine, serine, threonine, and valine being present in less than half the concentration observed in biotin-optimal cells. At early time intervals, the amino acid pool of biotin-deficient yeast contained lower concentrations of all amino acids except alanine. After more prolonged incubation, several amino acids accumulated in the pool of biotin-deficient yeast, but citrulline and ornithine accumulated to appreciable levels. The addition of aspartate to the growth medium resulted in a decrease in the amino acid content of biotin-optimal cells but caused a marked increase in the concentration of amino acids in biotin-deficient cells. The pools of biotin-deficient yeast grown in the presence of aspartate displayed a marked reduction in every amino acid with the exception of aspartate itself. These data provide evidence that the amino acid content of yeast cells and their free amino acid pools are markedly affected by biotin deficiency as well as by supplementation with aspartate, indicating that aspartate plays a major role in the nitrogen economy of yeast under both normal as well as abnormal nutritional conditions.
Chloramphenicol and the Stimulation of Ribonucleic Acid Synthesis in
Escherichia coli
Authors: Kaplan Sam
Published: January 2020

Data have been obtained which imply that chloramphenicol stimulation of ribonucleic acid (RNA) synthesis is a result of the accumulation of aminoacyl transfer RNA (tRNA) molecules. The data also support the hypothesis that chloramphenicol exerts an additional effect upon the stimulation of RNA synthesis. This effect may be at the level of the ribosome or the aminoacyl tRNA, or of both. It is this effect combined with the presence of aminoacyl tRNA that results in stimulation by chloramphenicol of RNA synthesis.
Suppression of Proline Requirement of
proA
and
proAB
Deletion Mutants in
Salmonella typhimurium
by Mutation to Arginine Requirement
Authors: Kuo Tseng-Tong , Stocker B. A. D.
Published: January 2020

Eleven variants able to grow without proline (provided arginine was absent) were obtained by spontaneous mutation from
Salmonella typhimurium
LT7
proA
and
proAB
deletion mutants. Suppression resulted from mutation at
argG
, which specifies N
α
-acetylornithine δ-transaminase. In the absence of exogenous arginine, deficiency of this enzyme would cause derepression of the arginine pathway and accumulation of
N
-acetylglutamic γ-semialdehyde.
N
-acetylglutamic γ-semialdehyde, if deacetylated, would produce glutamic γ-semialdehyde, the proline precursor whose synthesis from glutamate is blocked in
proA
and
proAB
mutants. All of the mutants grew only slowly (some very slowly) if not supplied with arginine. Sonic-treated preparations of eight mutants had no measurable acetylornithine δ-transaminase activity, but those of the three mutants least dependent on arginine had 0.11, 0.28, and 1.48 of wild-type activity; presumably, their enzymes have low specific activity, at least in vivo. Phage P22 cotransduced
argG
and
strA
. Genetic analysis showed that the minor degree of arginine dependence of the mutant with greater than wild-type in vitro enzyme activity was a characteristic of its
argG
allele, not the result of modification of the
argG
phenotype by mutation elsewhere.
Uptake and Utilization of
S
-Adenosyl-
l
-Methionine and
S
-Adenosyl-
l
-Homocysteine in an Adenine Mutant of
Saccharomyces cerevisiae
Authors: Knudsen Richard C. , Moore Keith , Yall Irving
Published: January 2020

An adenine mutant of
Saccharomyces cerevisiae
was able to utilize
S
-adenosyl-
l
-methionine (SAM),
S
-adenosyl-
l
-homocysteine (SAH), or adenine as sources for growth and ribonucleic acid (RNA) synthesis. Exogenous SAM or SAH was degraded after entering the cell, and the adenine moiety was reutilized in the endogenous synthesis of the thionium compounds. Part of this endogenous synthesis proceeds from an undetermined de novo system of purine synthesis which contributes significantly to the synthesis of SAM and less so to the RNA purines. Some of the methyl groups of exogenous SAM-methyl-
3
H were incorporated into ribosomal and transfer RNA. Methionine partially antagonized this incorporation. The uptake of SAM-adenine-
8
-
14
C
was not affected by the presence of equal quantities of SAH or adenine in the medium. Exogenous SAM affected the uptake of exogenous SAH-adenine-
8
-
14
C
or adenine-
8
-
14
C
. Exogenous SAH inhibited the uptake of exogenous adenine-
8
-
14
C
.
Collagenolytic Activity of Bacteria
Authors: Waldvogel Francis A. , Swartz Morton N.
Published: January 2020

Actively growing aerobic and anaerobic bacteria were screened by a plate assay, with reconstituted guinea pig collagen as a substrate, for their ability to produce a collagenolytic factor. Collagenolytic activity was not demonstrated among the aerobic organisms tested, with the exception of one strain of
Staphylococcus aureus
(only when grown under anaerobic conditions). Collagenolytic activity, however, was detected in cultures of
Clostridium tetani
and
Bacteroides
species other than
B. melaninogenicus
. Collagenolytic activity of these organisms could be confirmed by measuring the amount of hydroxyproline liberated from the collagen gel during growth. Although collagenase production by
Pseudomonas aeruginosa
has been suggested in previous reports, our results were negative. An extracellular fraction of
P. aeruginosa
was able to hydrolyze a synthetic hexapeptide Cbz-glycyl-
l
-prolyl-glycyl-glycyl-
l
-prolyl-
l
- alanine, but was without detectable effect on reconstituted collagen.
Effects of Carbon Dioxide on Growth and Maltose Fermentation by
Bacteroides amylophilus
Authors: Caldwell Daniel R. , Keeney Mark , Van Soest Peter J.
Published: January 2020

The requirement of carbon dioxide for growth of
Bacteroides amylophilus
is quantitatively similar to that of certain other rumen bacteria. Carbon dioxide could be replaced by bicarbonate, but not by formate or certain amino acids. Label from
14
CO
2
was incorporated into the succinate produced during maltose fermentation by
B. amylophilus
, and during glucose fermentation by
B. ruminicola
, and during cellobiose fermentation by
B. succinogenes
. All of the incorporated label could be associated with the carboxyl function of the molecule. The depression in radioactivity per micromole of carbon in the succinate formed from the fermentation of uniformly labeled
14
C-maltose by
B. amylophilus
was greater than would be expected if all of the succinate formed was produced via a direct CO
2
fixation pathway(s) involving phosphoenolpyruvate or pyruvate; the radioactivity per micromole of carbon suggests that as much as 60% of the total succinate results from a pathway(s) involving direct CO
2
fixation. Maltose fermentation by
B. amylophilus
was dependent upon CO
2
concentration, but CO
2
concentration could not be shown to influence either the fermentation end-product ratios or the proportion of total succinate formed attributable to CO
2
fixation.
Action Spectrum for Growth Delay Induced in
Escherichia coli
B/r by Far-Ultraviolet Radiation
Authors: Takebe Hiraku , Jagger John
Published: January 2020

An action spectrum for growth delay induced in
Escherichia coli
B/r by far-ultraviolet radiation (230 to 295 nm) was obtained. It resembles the action spectrum for killing obtained in the same experiments, indicating that the chromophore for growth delay is probably the same as the chromophore for killing. Another action spectrum for killing, obtained under conditions more suitable for chromophore identification, suggests that nucleic acid, either deoxyribonucleic acid or ribonucleic acid, is the chromophore for growth delay induced by far ultraviolet. Isoprenoid quinones, which seem to be important chromophores for growth delay induced by near-ultraviolet radiation (above 300 nm), appear to play a negligible role in growth delay induced by wavelengths below 300 nm.
Regulation of Synthesis of Glutamine Synthase in
Bacillus subtilis
Authors: Rebello John L. , Strauss Norman
Published: January 2020

A study of the regulation of the synthesis of the enzyme glutamine synthase in
Bacillus subtilis
was initiated. An assay, based on the measurement of glutamo-hydroxamate, was used to characterize the enzyme in crude preparations and in toluene-treated cells. Determinations were made of the Michaelis constants for adenosine triphosphate, hydroxylamine, and glutamate (9 × 10
−3
, 4 × 10
−3
, and 2.2 × 10
−2
m
, respectively), the
p
H optimum (7.6 to 7.7), and the stability. The differential rate of synthesis was determined under various growth conditions. The enzyme was found to be relatively insensitive to regulation. Partial repression was caused by glutamine, arginine, asparagine, and glutamate, or by carbon limitation in a chemostat. Derepression was caused by exhaustion of externally added amino acids or by nitrogen limitation in a chemostat.
Intraphagocytic Degradation of Group A Streptococci: Electron Microscopic Studies
Authors: Ayoub Elia M. , White James G.
Published: January 2020

The morphological changes that occur during intraphagocytic digestion of group A streptococci were studied by electron microscopy The first evidence of degradation of the ingested organism was the appearance of reticular changes in the bacterial endoplasm. This was followed by gradual swelling and dissolution of the bacterial wall, with final degradation of all the constitutuents to electron-dense debris. Accompanying changes in the phagocytic cell were observed; they consisted of vacuole formation, fusion of lysosomes with the wall of the yacuole, release of the lysosomal contents into the vacuole, and aggregation of the lysosomal contents around the ingested organism. Changes in the morphology of the organism similar to those observed during intraphagocytic digestion were also obtained by subjecting streptococcal cells to the action of the phage-associated lysin.
Surface Features of
Bacillus polymyxa
Spores as Revealed by Scanning Electron Microscopy
Authors: Murphy Judith A. , Campbell L. Leon
Published: January 2020

The surface features of
Bacillus polymyxa
spores were compared by use of thin sections, carbon replicas, and the scanning electron microscope. Some features of the characteristic ridges, previously reported in ultrathin sections and carbon replicas of spores of this species, were more clearly revealed with the scanning electron microscope. A three-dimensional image is provided because of the greater depth of focus possible with this instrument. End-on views of
B. polymyxa
spores readily illustrate the polygonal porelike structure present.
Mycoplasma laidlawiiin Human Burns
Authors: Markham Jean G. , Markham N. P.
Published: January 2020

Mycoplasma laidlawiiwas recovered from burns from 13 of 52 patients. In most cases, cocci or bacilli were isolated simultaneously.
Sporulation of Yeast Harvested During Logarithmic Growth
Authors: Roth Robert , Halvorson H. O.
Published: January 2020

Rapid and abundant sporulation of yeast can be obtained, with cells harvested during logarithmic growth, by employing potassium acetate rather than glucose as a carbon source.
Effect of Enterotoxin B on Human Volunteers
Authors: Raj H. D. , Bergdoll M. S.
Published: January 2020

A dosage of 20 to 25 μg of pure enterotoxin B can produce clinical manifestations of enterotoxemia in man, who seems to be more sensitive than monkey.
Actinomycin D Sensitivity of Bacteria with Simple and Complex Cell Surfaces
Authors: Muschel Louis H. , Larsen Linda J.
Published: January 2020

The sensitivity of different bacteria to actinimycin D was not related to their cell surface morphology. Bacteria with simple and complex surfaces were both extremely susceptible.
Effect of Vibriocins on Members of the
Enterobacteriaceae
Authors: Datta Archana , Prescott Lawrence M.
Published: January 2020

Certain vibriocin producers exhibited antibacterial activity throughout the
Enterobacteriaceae
. To examine this phenomenon, an effective technique for demonstrating vibriocin production was developed.
Taxonomy of the Yeast Genus
Metschnikowia:
a Correction and a New Variety
Authors: Fell Jack W. , Pitt J. I.
Published: January 2020

Metschnikowia
isolates from ponds on Chatham Island, New Zealand, previously erroneously reported as
M. zobellii
, are described herein as
M. bicuspidata
var.
chathamia
var. n.
Effects of Nitrogen Dioxide on Pulmonary Cell Population
Authors: Gardner Donald E. , Holzman Robert S. , Coffin David L.
Published: January 2020

Studies from this laboratory have shown that ozone produces changes in the number and function of cells obtained by pulmonary lavage. In similar experiments, rabbits exposed to levels of NO
2
from ambient to 60 ppm demonstrated increased numbers of polymorphonuclear leukocytes in the lung washings. This phenomenon persisted for more than 72 hr after a single 3-hr exposure. When streptococci were instilled in the lungs of NO
2
-exposed anesthetized rabbits 30 min before lavage, a pronounced inhibition of phagocytic activity was observed. With these criteria, NO
2
appeared less effective than ozone as a pulmonary irritant.
Methanogenic Fermentation of Benzoate
Authors: Nottingham P. M. , Hungate R. E.
Published: January 2020

A methanogenic enrichment culture decomposed small concentrations of
14
C-benzoate to
14
C
4
and
14
CO
2
under stringently anaerobic conditions with or without preceding exposure to benzoate.
Antipolarity in the
ilv
Operon of
Escherichia coli
K-12
Authors: Wechsler James A. , Adelberg E. A.
Published: January 2020

The genes governing three of the enzymes of the isoleucine-valine biosynthetic pathway form the operon:
operator-ilvA-ilvD-ilvE
. The enzymes are:
ilvA
,
l
-threonine deaminase;
ilvD
, dihydroxy acid dehydrase; and
ilvE
, transaminase B. A nonsense mutation in the
ilvD
gene (
D-ochre
) and a nonsense mutation in the
ilvE
gene (
E-amber
) affect the properties of the proximal gene product,
l
-threonine deaminase (TD), in addition to inactivating the enzymes produced by the genes in which the mutations have occurred. The
D-ochre
mutation causes TD to move in diffusion and gel filtration experiments as though it were 30% smaller than the wild-type enzyme. The
E-amber
mutation causes TD to move in similar experiments as though it were much larger than the wild-type enzyme. Both mutations completely abolish the sensitivity of TD to
l
-isoleucine, the normal feedback inhibitor of the wild-type enzyme. The effects of the nonsense mutations on TD can be reversed in three ways: by genetic reversion of the
D-ochre
mutation; by treatment of the altered enzymes with 3.0
m
urea; and by forming a heterozygous diploid, containing the wild-type allele as well as the mutant allele of
ilvD
or
ilvE
. The results suggest that the subunits of TD undergo abnormal aggregation in the presence of the partial polypeptides produced by the mutant alleles of
ilvD
or
ilvE
; multi-enzyme aggregates in extracts of wild type, however, could not be detected.