bluuebunny/crossref_metadata_2025 huggingface dataset:
Characterization ofMycoplasma pulmonisVariants Isolated from Rabbits I. Identification and Properties of Isolates
Authors: Deeb Barbara J. , Kenny George E.
Published: January 2020

Mycoplasmashowing at least two colony types were isolated from the nares and oropharynx of New Zealand white rabbits. Two strains were purified by single-colony passages and characterized. Morphology by phase-contrast and electron microscopy was typical ofMycoplasmataceae. Both grew anaerobically as well as aerobically, caused hemolysis of guinea pig, sheep, and horse red blood cells, and fermented glucose. These characteristics are shared by members of the speciesM. pulmonis, commonly isolated from the respiratory tracts of laboratory rats and mice. By use of the growth-inhibition test and agar-gel double-diffusion tests, the two strains were found to be serologically related to each other and toM. pulmonisATCC 14267 but not to other representativeMycoplasmaspecies from man and animals.
Oligopeptide Uptake by
Bacteroides ruminicola
Authors: Pittman Kenneth A. , Lakshmanan Sitarama , Bryant Marvin P.
Published: January 2020

Bacteroides ruminicola
did not take up
14
C from exogenous
14
C-labeled
l
-proline or
14
C-labeled
l
-glutamic acid and took up very little
14
C from exogenous
14
C-labeled
l
-valine. Growing cultures of
B. ruminicola
rapidly took up
14
C from
14
C-proline-labeled peptides of molecular weights up to 2,000 and incorporated it into trichloroacetic acid-insoluble cell material. Uptake and incorporation did not occur at 0 C and were reduced or eliminated in glucose-starved cells, depending upon the length of time the cells were starved. The initial rate of uptake of peptides seemed to exhibit saturation kinetics, but it was impossible to establish this conclusively. The initial uptake of
14
C from peptides was not affected by chloramphenicol but the incorporation of it into trichloroacetic acid-insoluble cell material was virtually eliminated. Only moderate amounts of trichloroacetic acid-extractable, labeled material were present in cells during peptide uptake, whether or not chloramphenicol was present.
14
C-proline was rapidly released from labeled peptides during uptake, whether or not chloramphenicol was present. The amount of
14
C fixed into trichloroacetic acid-insoluble cell material was directly related to the size of peptides originally supplied in the medium. It is concluded that
B. ruminicola
possesses a general system for the uptake of peptides, that peptides are rapidly hydrolyzed during or after uptake, and that oligopeptides function only to supply amino acids in a form available to the organism.
Experimental Salmonellosis VIII. Postinfective Immunity and Its Significance for Conferring Cellular Immunity
Authors: Osawa Nobutaka , Kawakami Masaya , Kurashige Satonori , Mitsuhashi Susumu
Published: January 2020

In the process of live-vaccine immunization of
Salmonella enteritidis
infection in mice, the relation between the number of bacteria in the organs of mice and their protecting effect was studied. Treatment with antibiotics was used to control the number of immunizing bacteria in the tissues. Mice, which were infected with 10
−5
mg (1,000 mouse MLD) of virulent
S. enteritidis
and treated with kanamycin simultaneously, acquired high antilethal resistance against infection with the same organisms. However, the administration of large amounts of kanamycin, which caused a rapid decrease in bacterial numbers in the organs of infected mice, was incapable of conferring immunity. This indicated the necessity of persistence of live bacteria in the host for the production of immunity. A large number of microorganisms were maintained for 53 weeks in a diffusion chamber inserted into the mouse abdominal cavity. The mice implanted with diffusion chambers containing large numbers of virulent
S. enteritidis
did not acquire antilethal resistance against infection with the same organisms, although agglutinins against
S. enteritidis
were observed in these mice. Agglutinin was also found in the fluid contained in diffusion chambers inserted into mice immunized with a killed vaccine of
S. enteritidis
. This indicated that antibody penetrated the membrane filter of diffusion chambers from outside to inside and vice versa. From these results, it is suggested that contact of live microorganisms with the host cell is necessary for conferring postinfective immunity in salmonellosis.
Glucose and Gluconate Metabolism in a Mutant of
Escherichia coli
Lacking Gluconate-6-phosphate Dehydrase
Authors: Zablotny R. , Fraenkel D. G.
Published: January 2020

A mutant lacking gluconate-6-phosphate dehydrase (the first enzyme of the Entner-Doudoroff pathway) was isolated after ethyl methane sulfonate mutagenesis of
Escherichia coli
. Other enzymes of gluconate metabolism (gluconokinase, gluconate-6-phosphate dehydrogenase, and 2-keto-3-deoxygluconate-6-phosphate aldolase) were present in the mutant. When the mutant was grown on gluconate-
1
-
14
C
, alanine isolated from protein was unlabeled, showing that the dehydrase was absent in vivo and that the sole pathway of gluconate metabolism in the mutant was the hexose monophosphate shunt. The mutant grew on gluconate with a doubling time of 155 min, compared with the parent strain's 56 min. On glucose and fructose it grew with normal doubling times. Thus, in
E. coli
, the Entner-Doudoroff pathway is used for gluconate metabolism but not for glucose metabolism.
Growth of Pathogenic
Leptospira
in Chemically Defined Media
Authors: Shenberg Esther
Published: January 2020

A protein-free chemically defined medium for cultivation of pathogenic
Leptospira
was developed. The medium permitted continued serial subculturing of 9 serogroups (52 strains) of the 12 serogroups (61 strains) tested. Growth was initiated from small inocula, and the growth rate and maximal cell yields were similar to those on serum-containing media. The nutritional requirements of serogroups
L. canicola, L. pomona
, and
L. grippotyphosa
were studied in a basal medium composed of inorganic salts, a fatty acid, vitamin B
12
, and thiamine. All strains tested utilized ammonium chloride as the sole nitrogen source. A fatty acid, vitamin B
12
, and ferrous ions were essential. Growth was stimulated by thiamine, potassium, and calcium ions.
Detoxification of
Salmonella typhimurium
Lipopolysaccharide by Ionizing Radiation
Authors: Previte Joseph J. , Chang Y. , El-Bisi H. M.
Published: January 2020

The efficiency of ionizing radiation in detoxifying the lethal determinant(s) of the lipopolysaccharide (LPS) of
Salmonella typhimurium, S. enteritidis
, and
Escherichia coli
in aqueous solution and associated with heat-killed
S. typhimurium
cells in suspension decreased with doses above 1 Mrad. The 50% end point of inactivation was more than 7.0 Mrad for heat-killed salmonellae and 4.8, 4.5, and 1.0 Mrad for the LPS of
S. typhimurium, S. enteritidis
, and
E. coli
, respectively. After exposure to 20 Mrad,
S. typhimurium
LPS retained a small portion of its lethal properties although the
ld
50
was much greater than 9.5 mg per 20-g mouse. However, at −184 C, no inactivation of the lethal determinant(s) occurred after exposure to as much as 20 Mrad. This demonstrated the significance of the indirect effect and the mobility and formation of free radicals. At 22 C, the optical density at 400 mμ increased and the
p
H decreased with increasing radiation dose, but no qualitative changes were observed in the infrared spectrum. No change was observed in the pyrogenicity of
S. typhimurium
LPS; a slight decrease in antigenicity was revealed when 6 days, but not when 1 day, elapsed between vaccination and challenge in the mouse protection test. The results were interpreted as evidence of the existence of two or more lethal and antigenic determinants. The differential effect of radiation on these properties and on the pyrogenic component(s) probably are indicative of separate functional sites for lethal, antigenic, and pyrogenic activities.
Synchronous Growth and Sporulation of
Bacillus megaterium
Authors: Imanaka Hiroshi , Gillis John R. , Slepecky Ralph A.
Published: January 2020

Filtration of late log-phase cultures of
Bacillus megaterium
ATCC 19213 grown on defined sucrose salts medium (SS) or SS plus glutamate medium (SSG) through nine layers of Whatman no. 40 filter paper in a fritted-glass disc Büchner funnel resulted in filtrates containing cells which showed synchronous growth and proceeded to sporulation. SS cells completed one synchronous division after filtration; sporulation ensued after the cessation of growth. SSG cells completed two synchronous divisions and sporulation occurred during the second division. A high degree of synchrony of vegetative growth of SSG cells was evident by the stepwise pattern of growth, by the doubling of cell numbers at each division, the high division index, and by the rapid formation of sporulation cell types and homogeneity of cell types in the filtered cultures when compared with asynchronous cultures. Because the described system gives both good growth and sporulation synchrony, the method should be useful in delineating early events in sporulation and their regulation.
Comparative Inductive Responses of Two β-Galactosidases of
Neurospora
Authors: Bates William K. , Hedman Stephen C. , Woodward Dow O.
Published: January 2020

The activities of the two β-galactosidases of
Neurospora
increased in response to the presence of lactose or galactose.
d
-Xylose preferentially induced higher levels of activity in one of these enzymes. The initial period of the inductive response was examined in cultures transferred from noninducing to inducing media. Variations in the ratio of activities of these enzymes during this induction period indicate that their induction was not coordinate. The induction of the β-galactosidases of
Neurospora
was less sensitive to low concentrations of inducers than was the induction of the β-galactosidase of bacteria; the time lag of induction was greater in the eucaryotic organism, and the maximal induction of active enzyme was less than that observed in bacteria.
Evidence for Multiple Forms of Isocitrate Lyase in
Neurospora crassa
Authors: Sjogren Robert E. , Romano Antonio H.
Published: January 2020

The effect of carbon source on isocitrate lyase formation was studied in a wildtype strain of
Neurospora crassa
and in a uridine-deficient mutant. A constitutive level of the enzyme was produced in a casein hydrolysate medium. The enzyme was repressed by glucose, although the two strains varied with respect to the degree of glucose repression. Acetate strongly stimulated isocitrate lyase formation. The enzyme formed in the presence of acetate differed in several respects from that formed in glucose-grown cells. Differences were found in
p
H-activity curves,
K
m
values, and in sensitivity to phosphoenolpyruvate inhibition. Diethylaminoethyl cellulose chromatography allowed separation of two enzymatically active components which showed different rates of heat inactivation. These data indicate the presence of multiple forms of isocitrate lyase in
Neurospora
.
Occurrence of 3-Amino-3,6-Dideoxyhexoses in
Salmonella
and Related Bacteria
Authors: Lüderitz O. , Ruschmann E. , Westphal O. , Raff R. , Wheat R.
Published: January 2020

Several species of
Salmonella, Citrobacter
, and
Arizona
were examined for the presence of 3-amino sugars, which were isolated from lipopolysaccharide hydrolysates by cation exchange chromatography and identified by paper and cation exchange chromatography in several systems and by specific colorimetric procedures. 3-Amino-3,6-dideoxyglucose was identified in
C. freundii
8090,
C. freundii
869,
S. halle, S. telaviv, S. dakar, S. wandsworth
, and
S. champaign;
3-amino-3,6-dideoxygalactose was found in
S. tranoroa
and
Arizona
24. Evidence suggests that these 3-amino sugars occur in lipopolysaccharides as the
N
-acetyl derivatives. The composition of the lipopolysaccharides containing the 3-amino sugars was determined, and the lipopolysaccharides were compared serologically in order to correlate chemotypes with serotypes. The lipopolysaccharides containing 3-amino-3,6-dideoxyglucose reacted with serogroups 28 or 39; those containing 3-amino-3,6-dideoxygalactose were found to react with group 55 antisera. The preparation of a lipopolysaccharide from the phenol phase of the 44% aqueous phenol extraction procedure is also reported.
Growth and Ultrastructure of
Rhodomicrobium vannielii
as a Function of Light Intensity
Authors: Trentini William C. , Starr Mortimer P.
Published: January 2020

Cells of
Rhodomicrobium vannielii
were grown in a controlled environment at several different light intensities. Differential rates of bacteriochlorophyll (BChl) synthesis and specific BChl contents were inversely related to the light intensity. On the other hand, the specific rate of growth—before reaching a maximal value—was directly related to the intensity of the light. Thin sections of cells grown at moderately low light showed the typical peripherally located, symmetrically distributed lamellate system, whereas an asymmetrical distribution of a less extensive lamellate system occurred in cells grown at high light intensities. It is proposed that a limited number of individual units of the lamellate system are originally derived from inward folds of the cytoplasmic membrane, and that subsequent lamellae arise by proliferation, including possible forking and definite folding back, of the few original lamellar membranes.
Reassociation of Purified Lipopolysaccharide and Phospholipid of the Bacterial Cell Envelope: Electron Microscopic and Monolayer Studies
Authors: Rothfield L. , Horne R. W.
Published: January 2020

Phosphatidyl ethanolamine and lipopolysaccharide were extracted and purified from the cell envelope fractions of
Escherichia coli
and
Salmonella typhimurium
. The two components were studied separately and after recombination, by use of electron microscopy and monolayer techniques, and by measuring their ability to participate in the enzyme-catalyzed uridine diphosphate-galactose:lipopolysaccharide α, 3 galactosyl transferase reaction, which requires a lipopolysaccharide-phospholipid complex as substrate. Electron microscopy of purified lipopolysaccharide showed a uniform population of hollow spheres, with each sphere bounded by a continuous leaflet. The diameter of the spheres was approximately 500 to 1,000 A, and the thickness of the enveloping leaflet was approximately 30 A. Phosphatidyl ethanolamine showed a regular lamellar structure. When lipopolysaccharide and phosphatidyl ethanolamine were mixed under conditions of heating and slow-cooling, the leaflet of the lipopolysaccharide spheroids appeared to extend directly into the phosphatidyl ethanolamine structure, with continuity between the two leaflets. Various stages of penetration were seen. At high concentrations of lipopolysaccharide, there were disruptive changes in phosphatidyl ethanolamine leaflets similar to those seen when saponin acts on cholesterol-lecithin leaflets. Monolayer experiments indicated that lipopolysaccharide penetrated a monomolecular film of phosphatidyl ethanolamine at an air-water interface, as revealed by an increase in surface pressure. The results indicate that a common leaflet structure containing lipopolysaccharide and phosphatidyl ethanolamine may be formed in vitro, and suggest that a similar leaflet may exist in the intact bacterial cell envelope.
Nature of the Skin-reactive Principle in Culture Filtrates Prepared from
Paracoccidioides brasiliensis
Authors: Restrepo-Moreno Angela , Schneidau John D.
Published: January 2020

Mycelial and yeast-phase culture filtrates prepared from three strains of
Paracoccidioides brasiliensis
exhibited equal reactivity in sensitized guinea pigs. Ethyl alcohol-precipitated fractions obtained from the culture filtrates also showed no difference in reactivity between mycelial and yeast phase when tested in sensitized guinea pigs. Chemical analyses of the ethyl alcohol-precipitated fractions revealed the presence of seven aliphatic amino acids in both the mycelial- and yeast-phase products. Glucose, galactose, arabinose, and glucosamine were also detected, but the relative proportions of these sugars were different for the mycelial phase as compared with the yeast phase. Both the mycelial- and yeast-phase ethyl alcohol precipitated fractions contained 2 to 4% nitrogen, but no protein or nucleic acid could be detected. Removal of nitrogen from the ethyl alcohol-precipitated fractions by chloroform extraction resulted in an almost complete loss of skin reactivity, whereas the material recovered from the chloroform, which contained most of the nitrogen, still exhibited almost as much reactivity as was present prior to extraction. A considerable portion of the reducing substances was removed along with the nitrogen by the chloroform extraction, suggesting a strong chemical link between the carbohydrate and the peptide portions of the active moiety. Since no protein was present in the fractions, it was presumed that the active moiety is a glycopeptide.
Mouse-protective Properties of
Bordetella pertussis
Serotypes in Passive Tests
Authors: Eldering Grace , Holwerda Jack , Baker Julia
Published: January 2020

In a passive protection procedure in which the
ed
50
values of
Bordetella pertussis
antisera were determined, groups of mice were given graded intraperitoneal doses of serum, followed the next day by intracerebral challenge with 100,000 organisms. Antiserum produced with
B. pertussis
culture 5373, serotype 1.3, protected mice against challenge with culture 18-323, serotype 1.2.3, as effectively as did an antiserum produced with a serotype 1.2.3 culture. When two groups of mice similarly treated with pertussis immune serum were challenged with culture 353Z (serotype 1) and 18-323, respectively, much lower
ed
50
values were obtained with the animals challenged with 353Z. Passive protection tests with adsorbed antiserum gave equivocal results, suggesting that some of the adsorbing antigen remained in the serum and interfered with the tests. There was no evidence that serotype is related to protection.
Inhibition by Actinomycin D of Uridine Diphosphoglucose Synthetase Activity During Differentiation of
Dictyostelium discoideum
Authors: Wright Barbara , Pannbacker Richard
Published: January 2020

Actinomycin D inhibits the increase in specific activity of uridine diphosphoglucose synthetase during differentiation of the cellular slime mold,
Dictyostelium discoideum
. The degree to which this inhibition occurs is strictly correlated with, and may result from, the general inhibition of morphogenesis by actinomycin D.
Fumarate Reductase Activity ofStreptococcus faecalis
Authors: Aue B. J. , Diebel R. H.
Published: January 2020

Some characteristics of a fumarate reductase fromStreptococcus faecalisare described. The enzyme had apH optimum of 7.4; optimal activity was observed when the ionic strength of the phosphate buffer was adjusted to 0.088. TheKmvalue of the enzyme for reduced flavin mononucleotide was 2 × 10−4mas determined with a 26-fold preparation. In addition to fumarate, the enzyme reduced maleate and mesaconate. No succinate dehydrogenase activity was detected, but succinate did act as an inhibitor of the fumarate reductase activity. Other inhibitors were malonate, citraconate, andtrans-, trans-muconate. Metal-chelating agents did not inhibit the enzyme. A limited inhibition by sulfhydryl-binding agents was observed, and the preparations were sensitive to air oxidation and storage. Glycine, alanine, histidine, and possibly lysine stimulated fumarate reductase activity in the cell-free extracts. However, growth in media supplemented with glycine did not enhance fumarate reductase activity. The enzymatic activity appears to be constitutive.
Effect of Different Nutritional Conditions on the Synthesis of Tricarboxylic Acid Cycle Enzymes
Authors: Hanson Richard S. , Cox Donald P.
Published: January 2020

The effect of various nutritional conditions on the levels of Krebs cycle enzymes in
Bacillus subtilis, B. licheniformis
, and
Escherichia coli
was determined. The addition of glutamate, α-ketoglutarate, or compounds capable of being catabolized to glutamate, to a minimal glucose medium resulted in complete repression of aconitase in
B. subtilis
and
B. licheniformis
. The synthesis of fumarase, succinic dehydrogenase, malic dehydrogenase, and isocitric dehydrogenase was not repressed by these compounds. It is postulated that glutamate or α-ketoglutarate is the true corepressor for the repression of aconitase. A rapidly catabolizable carbon source and α-ketoglutarate or glutamate must be simultaneously present for complete repression of the formation of aconitase. Conditions which repress the synthesis of aconitase in
B. subtilis
restrict the flow of carbon in the sequence of reactions leading to α-ketoglutarate but do not prevent glutamate oxidation in vivo. The data indicate that separate and independent mechanisms regulate the activity of the anabolic and catabolic reactions of the Krebs cycle in
B. subtilis
and
B. licheniformis
. The addition of glutamate to the minimal glucose medium results in the repression of aconitase, isocitric dehydrogenase, and fumarase, but not malic dehydrogenase in
E. coli
K-38.
Isolation and Characterization of Glycolipids from Some Photosynthetic Bacteria
Authors: Constantopoulos G. , Bloch K.
Published: January 2020

Glycosyl glycerides have been found in substantial amounts in
Chloropseudomonas ethylicum
but could not be detected in two strains of
Rhodopseudomonas palustris. Rhodospirillum molischianum
possibly contains small amounts of monoglycosyl diglyceride. The glycolipids of
C. ethylicum
have been separated into two components. One of these, glycolipid I, is a monogalactosyl diglyceride. Glycolipid II, upon acid hydrolysis, yields galactose, rhamnose, and a third, unidentified sugar. The glycolipids or total lipids of the photosynthetic bacteria examined contained saturated and monounsaturated, but none of the more highly unsaturated, fatty acids.
Release of Proteinase from Mycelium of
Mucor hiemalis
Authors: Wang Hwa L.
Published: January 2020

When
Mucor hiemalis
NRRL 3103 was grown in soybean medium, only a small fraction of the proteinase produced by the organism appeared in the culture filtrate, whereas the bulk of the enzyme was bound to the mycelial surface. Optimal
p
H of the proteinase ranged from 3.0 to 3.5. Inclusion of sodium chloride or other ionizable salts in the growth medium, however, resulted in the liberation from the mycelium of the loosely bound enzyme as it was formed. Maximal release of proteinase was achieved at a sodium chloride concentration of 0.5
m
. The loosely bound proteinase was eluted also from intact resting mycelium by ionizable salts but not by water or by nonionizable substances. The amount of enzyme eluted from the mycelium depended upon the concentration of sodium chloride up to 0.3
m
. Since liberation took place rapidly even at 0 C, a loose ionic linkage must exist rather than a biochemical binding of the enzyme to the mycelium. The recovery of proteolytic activity from repeated salt extractions was greater than that originally detected in the intact mycelium, possibly owing to unmasking of more active enzymes or functional groups. Further proteinase activity was released when salt-extracted mycelium was ruptured. Part of the proteinase thus observed was firmly attached to the cell fraction, and part of it appeared in the supernatant fluid. These conditions implied the presence of intracellular or firmly attached proteinase which could be partially released.
Biochemical Studies of Bacterial Sporulation IV. Inorganic Pyrophosphatase of Vegetative Cells and Spores of
Bacillus megaterium
Authors: Tono Henrique , Kornberg Arthur
Published: January 2020

Inorganic pyrophosphatase activities extracted from vegetative cells and spores of
Bacillus megaterium
were compared and found to be similar in behavior on polyacrylamide gel electrophoresis, in metal and
p
H requirements for activity, and in response to inhibitors. In the sporulating cell, an additional electrophoretic species of the enzyme was observed which could be partially converted to the principal form by treatment with Mn
++
; both forms of the enzyme required Mn
++
for stabilization in solution as well as for activity.
Altered Protein Formation as a Result of Suppression in
Neurospora Crassa
Authors: Rachmeler Martin
Published: January 2020

The mutant td201 of
Neurospora crassa
is mutated in the
trp-3
locus and forms an altered tryptophan synthetase. A suppressor mutation,
su2-6
, in this mutant, unlinked to the
trp-3
locus, results in the production of wild-type tryptophan synthetase activity, which accounts for the alleviation of the tryptophan or indole requirement. This enzyme activity is associated with a protein physically dissimilar to the wild-type enzyme. A second altered protein, a serologically cross-reacting material is also formed in the suppressed mutant, in addition to the altered enzyme normally formed by the td201 mutant. Normal growth, equivalent to that of wild type, is not restored in the suppressed mutant even with tryptophan supplementation. The relationship of the data to possible mechanisms of suppression is discussed.
Application of the Fluorescent-Antibody Technique to an Ecological Study of Bacteria in Soil
Authors: Hill I. R. , Gray T. R. G.
Published: January 2020

The fluorescent-antibody technique was used to identify cells and spores of
Bacillus subtilis
and cells of
B. circulans
from soil. From cells grown in three broth media of different nutrient status, i.e., a cold extracted soil medium (CSE), an unamended autoclaved soil extract (HSE), and nutrient broth (NB), antisera were produced with both quantitative and qualitative differences in antibody content. The specificities of antisera to two strains of each of the
Bacillus
species were determined. Antisera for
B. subtilis
O antigens were species-specific and showed no cross-reactions, whereas those for the
B. circulans
O antigens were strain-specific and in some cases showed cross-reactions with
B. alvei
. This cross-reaction was removed by absorption of the antiserum with
B. alvei
O antigen. Fluorescein isothiocyanate γ-globulin conjugates prepared from these antisera showed the same specificity reactions. A method for staining bacteria on soil particles was developed, by use of small staining troughs. By mounting stained soil particles on slides and irradiating them with transmitted and incident ultraviolet blue light, bacteria on both mineral and organic particles, taken directly from soil, could be observed. Fluorescent antibodies against cells grown in CSE gave brighter fluorescence of stained bacteria on soil particles than did fluorescent antibodies against cells grown in either HSE or NB. Colonies of both
Bacillus
species were generally small and localized. Spore antisera, though not rigorously tested for specificity, were used to identify spores of
B. subtilis
on soil particles. The uses and implications of the technique in soil bacteriology are discussed.
Genetic Analysis of Mutant Strains of
Escherichia coli
Requiring
p
-Aminobenzoic Acid for Growth
Authors: Huang M. , Pittard J.
Published: January 2020

Mutant strains of
Escherichia coli
K-12 which required
p
-aminobenzoic acid for growth were isolated. The mutations were mapped by conjugation and by transduction, and two genes concerned with the biosynthesis of
p
-aminobenzoic acid were identified.
In Vitro and In Vivo Characterization of Pyocin
Authors: Higerd Thomas B. , Baechler Charles A. , Berk Richard S.
Published: January 2020

Pyocin, a bacteriocin obtained from lysates of ultraviolet-induced cultures of
Pseudomonas aeruginosa
was characterized in vitro and in vivo after 1,000-fold purification by chemical, column, and differential centrifugation procedures. Electron micrographs of negatively stained pyocin preparations contained rod-shaped particles which resembled the contractile tail protein of the T-even phages of
Escherichia coli
. Although two separate and distinct pyocin fractions were eluted from diethylaminoethyl cellulose (
p
H 7.5) during the purification procedure, the particles appeared identical. In addition, the two fractions exhibited a close correlation between their titers and the particle numbers as observed in the electron microscope. The particles were approximately 20 by 90 mμ with a core diameter of 5 mμ and a sheath length of 50 mμ. Neither intact phage nor ghosts were seen in any of the preparations, although ringlets of two different diameters, which appeared to correspond to the diameters of the sheath and inner core, were observed. Other studies indicated that, although crude preparations were stable to freezing and thawing, purified preparations lost all of their activity under similar treatment. However, the addition of 50% glycerol to purified preparations completely protected activity. Conversely, aged normal human or rabbit sera enhanced the antibacterial activity of pyocin approximately fourfold, although serum albumin and hemoglobin had no effect. In vivo studies indicated that purified pyocin was not lethal for mice when injected intraperitoneally in concentrations of 28,000 to 1,400,000 units (5.6 to 276 μg of protein), nor was 7,200 to 36,000 units dermonecrotic for rabbits.
Purification and Chemical Composition of Reticulate Bodies of the Meningopneumonitis Organisms
Authors: Tamura Akira , Matsumoto Akira , Higashi Noboru
Published: January 2020

Reticulate bodies of the meningopneumonitis (MP) microorganism were purified from L cells 18 hr after infection by the combination of differential centrifugation in 30% sucrose solution and potassium tartrate density gradient centrifugation. It was ascertained by electron microscopy that purified preparations of reticulate bodies obtained were almost entirely free of host-cell components and of infectious elementary bodies of MP microorganisms. Purified reticulate bodies were easily disrupted by mechanical agitation, and it was observed in shadowed preparation that ribosome-like particles 15 mμ in diameter were scattered from broken reticulate bodies. In shadowed preparations, reticulate bodies were found to range in size from 1.0 to 1.6 μ in diameter, but in cross-section the range was 0.5 to 1.0 μ. In these preparations, the purified reticulate bodies were irregular in shape, round or oval, and were composed of rather homogenous, amorphous, or reticulate material with moderate density. Some particles exhibited a less-dense internal structure, in which a coarse fibrous reticulum was seen. Chemical fractionation of32P-labeled purified reticulate bodies showed that they contained three times more ribonucleic acid (RNA) than deoxyribonucleic acid, with the RNA being composed primarily of 21S, 16S, and 4SRNA. No infectivity of purified reticulate bodies could be demonstrated.
Isolation of Ribosome Particles from Meningopneumonitis Organisms
Authors: Tamura Akira
Published: January 2020

In ribonucleic acid (RNA) extracted by phenol and sodium dodecyl sulfate from purified reticulate bodies of meningopneumonitis (MP) organisms, 21
S
, 16
S
, and 4
S
RNA were found by sucrose density gradient sedimentation analysis. When purified reticulate bodies were homogenized by sonic treatment or by treatment with sodium deoxycholate and were fractionated by differential centrifugation, more than 50% of the RNA was recovered in the fraction which was sedimented by centrifugation at 105,000 ×
g
for 2 hr, but not at 13,000 ×
g
for 20 min. From homogenates prepared in this manner, 50
S
and 30
S
particles containing RNA were isolated by sucrose density gradient centrifugation. These 50
S
and 30
S
particles were also found in lysates of cytoplasmic fractions of infected cells which were labeled by
32
P during 17 to 17.5 hr or 15 to 18 hr after infection. The synthesis of 50
S
and 30
S
particles was not inhibited by actinomycin D. When infected cells were homogenized in the presence of 0.01 or 0.02
m
MgCl
2
, 70
S
particles were isolated instead of 50
S
and 30
S
particles. When dialyzed against low concentrations of MgCl
2
, the 70
S
particles dissociated to 50
S
and 30
S
particles. The base ratio of the 70
S
particles is very similar to that of 16
S
plus 21
S
RNA. The characteristics of the 70
S
, 50
S
, and 30
S
particles suggest that these are ribosome particles, similar to bacterial ribosomes.
Medium-dependent Alteration of Lysine Transfer Ribonucleic Acid in Sporulating
Bacillus subtilis
Cells
Authors: Lazzarini Robert A. , Santangelo Edith
Published: January 2020

The presence of the altered lysine transfer ribonucleic acid (tRNA) in
Bacillus subtilis
spores is strongly dependent on the medium on which the cells were sporulated. Cells sporulated on synthetic media or dilute complex media contain little or none of the new component, whereas those sporulated on concentrated complex media accumulate the altered tRNA. The accumulation begins during the fifth or sixth stage of sporulation, the formation of the tunic, and the appearance of refractility, respectively. Mutants blocked early in sporulation differ in their ability to accumulate the altered tRNA when cultured on the same complex medium. Of the four mutants examined, one failed to accumulate any of the RNA, whereas a second contained the full complement characteristic of spores. The third and fourth mutant contained small amounts of the material. It is tentatively concluded that the accumulation of the altered lysine tRNA is not obligate to sporulation but is an epiphenomenon of the process.
Infection in Mouse Peritoneal Cavity with a Pyrimidine-requiring Mutant and Naturally Occurring
Staphylococcus aureus
Strains
Authors: Mathieu L. G. , De Repentigny J. , Turgeon S. , Sonea S.
Published: January 2020

The lethal activity of a thymineless mutant of
Staphylococcus aureus
Wood 46 strain has been compared with that of three naturally occurring strains: parent Wood 46, Smith, and coagulase-negative SA-13. The thymineless mutant and the parent Wood 46 strain showed a sharp decline in culturable units from the peritoneal cavity in the first 4 hr after their injection. After 6 hr, that is, 2 hr before the mice began to die, the number of culturable units of the thymineless mutant was still declining, whereas that of the parent strain increased; for both strains, the number of units was still lower than that of the inoculum. Although the thymineless mutant, unlike the parent strain, was apparently unable to multiply in mouse peritoneal cavity, it killed mice at a similar rate. The highly virulent Smith strain known to multiply rapidly and the avirulent coagulase-negative SA-13 strain were used as additional controls. Under our experimental conditions, death of mice after the injection of the thymineless mutant in the peritoneal cavity did not seem to be due to bacterial multiplication but to toxicity, death being delayed by antitoxin. The pyrimidine-requiring auxotroph we used could be better material than killed bacteria to study some aspects of the lethal activity of
S. aureus
.
Macromolecular Synthesis in Newly Transformed Cells of
Bacillus subtilis
Authors: McCarthy Charlotte , Nester E. W.
Published: January 2020

The capacity of newly transformed cells of
Bacillus subtilis
to synthesize deoxyribonucleic acid (DNA), ribonucleic acid (RNA), and protein has been determined by following the kinetics of suicide after their exposure to tritiated precursors of each of these macromolecules. Competent cells, whether transformed or not, are heterogeneous with respect to DNA synthesis. About 40 to 50% are latent in DNA synthesis. This latency may persist for 2.5 to 3 hr since transformants are resistant to thymineless death for this period after DNA addition. The remainder of the transformants synthesize DNA at one-half the rate of the cells of the total population. Synthesis of stable RNA does not occur at an appreciable rate in newly transformed cells. Newly transformed cells, however, do synthesize protein extensively, as demonstrated by the lethality of incorporated tritiated amino acids. Either chloramphenicol or actinomycin D treatment during the time of exposure to the tritiated amino acid prevented the suicide of transformants.
Natural and Immune Human Antibodies Reactive with Antigens of VirulentNeisseria gonorrhoeae: Immunoglobulins G, M, and A
Authors: Cohen Irun R.
Published: January 2020

Natural and immune human antibodies reactive with heat-labile and heat-stable antigens of virulentNeisseria gonorrhoeaewere studied by use of an indirect fluorescent-antibody (IFA) procedure. The immunoglobulin class of the reactive antibodies was identified by using fluorescein-conjugated antisera specific for human IgG, IgA, or IgM in the IFA procedure. The effects of heat and mercaptoethanol on IFA reactivities were also studied. It appeared that antibodies of the IgG, IgM, and IgA classes present in the sera of both infected persons (immune antibodies) and normal persons with no history of gonococcal infection (natural antibodies) react with heat-stable somatic antigens. Immune IgG antibodies, however, were distinguishable from natural IgG antibodies by their ability to recognize heat-labile surface antigens. The distinction between natural and immune IgM antibodies was less obvious. IgM antibodies from both infected and normal persons appeared to react with heat-labile antigens. Some, but not all, infected persons had immune IgA antibodies to heat-labile as well as to heat-stable antigens. Treatment of sera with mercaptoethanol had no effect on IgG antibodies. The IFA activity of IgM antibodies was decreased, but not abolished. The effects of mercaptoethanol on IgA antibodies were variable. Some sera showed a decrease in IgA titer, and others showed an increase in IgA activity to certain antigens. Immune IgG antibodies were more resistant to heating than were natural IgG antibodies. Natural and immune IgM antibodies appeared equally sensitive to heating. IgA activity, on the other hand, was increased by heating sera at 60 C, but was decreased at higher temperatures. Thus, it appears that natural and immune human IgG antibodies toN. gonorrhoeaemay be distinguished by their interactions with heat-labile antigens and by their resistance to heating.
Division Delay Induced in
Escherichia coli
by Near-Ultraviolet Radiation
Authors: Phillips Stephen L. , Person Stanley , Jagger John
Published: January 2020

Beams of near-ultraviolet radiation at several principal emission lines of a mercury arc were isolated with a grating monochromator and directed upon cell suspensions. During subsequent incubation at room temperature in Nutrient Broth, the population was studied by removing samples and obtaining cell numbers and cell size distributions with an electronic cell counter. Division delay without lethality was observed. The shapes of the dose-response curves for induction, the doses of near-ultraviolet radiation required, and the action spectrum for division delay were found to be similar to those for growth delay (in broth) and for photoprotection. These findings indicate that all three effects, division delay, growth delay, and photoprotection, are induced by a common type of critical event. Changes in cell size distribution in the culture during incubation in Nutrient Broth after near-ultraviolet irradiation are very similar for control and irradiated populations, although these changes occur at a much later time in the irradiated population. This indicates that, in Nutrient Broth, the population recovers completely from the inhibition of growth and division, thus justifying use of the term “delay,” and suggesting that the damage is nongenetic.
Platelet Damaging Factor, a Fifth Activity of Staphylococcal α-Toxin
Authors: Manohar M. , Maheswaran S. K. , Frommes S. P. , Lindorfer Robert K.
Published: January 2020

Crude and purified staphylococcal α-toxin were used to demonstrate that the platelet-damaging effect of crude α-toxin represents a fifth activity of the α-toxin molecule. The homogeneity of the purified toxin employed was demonstrated by ultracentrifugation, Ouchterlony, and immunoelectrophoretic methods. Continuous-flow electrophoretic migration studies demonstrated under a variety of conditions that the platelet-damaging and the α-hemolytic activities migrated as a unit. Fractionation studies with the use of Sephadex G-100, carboxymethyl cellulose, and diethylaminoethyl cellulose failed to separate these two activities. Further, when α-toxin of demonstrated purity and crude toxin were adjusted to the same hemolytic activity, they possessed the same platelet-damaging activity. In addition, heat-reactivation studies with crude α-toxin revealed that the platelet-damaging effect was inactivated and reactivated in parallel with α-hemolytic activity. Comparable studies with purified α-toxin showed parallel inactivation of both activities at 60 C. Additional heating at 100 C failed to reactivate either activity. Electron micrographs revealed that purified α-toxin produced distinct degenerative changes in rabbit platelets. These studies also provided definite evidence that purified α-toxin has a damaging effect on human platelets. Monovalent α-antisera prevented platelet damage.
Protein Synthesis in Sonically Damaged
Escherichia coli
Authors: Amos Harold , Kuhn Anneli , Andre-Schwartz Janine
Published: January 2020

By gentle sonic treatment,
Escherichia coli
cells were modified to permit penetration of actinomycin D, adenosine triphosphate, trypsin, ribonuclease, and polyuridylic acid. The behavior of these “soniplasts” as protein-synthesizing particles was investigated.
Lytic Action of β(1-3)-Glucanase on Yeast Cells
Authors: Monreal J. , De Uruburu F. , Villanueva J. R.
Published: January 2020

Candida utilis, Saccharomyces cerevisiae, S. fragilis, Pichia polymorpha
, and
Hansenula anomala
yeast cells, harvested in the early logarithmic phase, were attacked with purified β(1–3)-glucanase from
Micromonospora chalcea
, which resulted in the liberation of protoplasts. The treated cells were observed under the electron microscope before the protoplasts were liberated. Differences in the cell walls of the enzyme-treated and untreated cells were observed. The action of the glucanase was also tested against isolated walls of
C. utilis
. The enzyme attacked the
S. cerevisiae
cell wall in a uniform manner. The attack on
S. fragilis
was located in certain zones of the cell wall, where breakage occurred and through which the protoplast emerged. On the other three yeasts, an intermediate attack was observed, not as definitely located as in
S. fragilis
, yet less uniformly than in
S. cerevisiae
.
Genetic Control of Flagellation in
Bacillus subtilis
Authors: Joys Terence M. , Frankel Ruth W.
Published: January 2020

Flagellation in
Bacillus subtilis
was shown to involve at least three loci: a gene
H
controlling the specificity of the flagellar antigen; a gene
fla
controlling the presence or absence of flagella; and a gene
mot
controlling the function of the flagella. The loci were shown to be nonallelic and unlinked in transformation tests. Strains W 23 and SB 108-b, a derivative of strain 168, were shown to differ in their major flagellar antigen.
Effect of Glucose on the Oxidation of β-Nitropropionic Acid by
Aspergillus flavus
Authors: Becker George E.
Published: January 2020

The rate of oxidation of β-nitropropionic acid (BNP) to nitrate by replacement cultures of
Aspergillus flavus
was linear. For each micromole of BNP assimilated, 1 μmole of nitrate was detected. BNP was readily oxidized at
p
H 3.8, but not at
p
H 6.8. In the presence of glucose, nitrate was not detected until after all of the glucose had been utilized. The effect of glucose is attributed to its inhibition of BNP uptake and also to its role as an electron donor for a nitrate reductase.
Relationships of X Irradiation to the Enhancement ofCandida albicansInfections
Authors: Gordee Robert S. , Simpson Patrick J.
Published: January 2020

Preirradiation significantly reduced the number ofCandida albicanscells required for theld50of experimentally infected mice. The start and extent of recovery of total leukocytes of preirradiated infected mice were proportional to the dose of X rays administered. During 10 days postinfection, heterophils of infected mice preirradiated with 400 R recovered to levels above unirradiated, uninfected controls but did not exceed those of unirradiated, infected animals. On the other hand, the more radiosensitive lymphocytes were depressed greatly, and a limited recovery below normal values was obtained. The lymph to heterophil ratio of uninfected mice irradiated with 400 R recovered to normal values by 11 days postirradiation. However, decreases in the ratio of unirradiated or X-irradiated infected mice showed little recovery. During 6 to 10 days postinfection, a reduction in microhematocrit values after a dose of 400 R alone was not observed when aC. albicansinfection was superimposed on X-irradiated mice. This difference was not due to changes in the red blood cell volume which was decreased by 400 R with or without infection, but was attributed to a greater decrease in plasma volume caused by a combination of X irradiation and infection. Reticulocyte counts indicated that recovery from the significant decrease in erythrocyte production caused by 400 R was retarded by a progressive infection. Elevated total serum protein of unirradiated mice at 6 days after infection was attributed to increases in α- and β-globulins. A dose of 400 R limited but did not prevent an increase α- and β-globulins upon subsequent infection.Candidaspecies infection or 400 R or both did not greatly affect the concentration of γ-globulins. The albumin to globulin ratio of irradiated, infected mice was intermediate between those ratios found after X irradiation or infection.
Subcellular Sites Involved in Lipid Synthesis in
Saccharomyces cerevisiae
Authors: Klein Harold P. , Volkmann Carol M. , Leaffer Morris A.
Published: January 2020

When the crude ribosomal fraction of
Saccharomyces cerevisiae
was separated into “light” and “heavy” fractions, fatty acid synthetase was concentrated in the former, whereas acetyl-Coenzyme A synthetase, fatty acid “desaturase,” and squalene oxidocyclase were found in the latter. The “desaturase” sedimented with the ribosomal material and was not solubilized by low concentrations of sodium deoxycholate (DOC). The other two systems found in the “heavy” fraction sedimented with the membranes, but, upon solubilization of the membranes by DOC, these enzyme systems remained as particles.
Cellular Sites for the Competence-provoking Factor of Streptococci
Authors: Pakula Roman
Published: January 2020

Immune globulins against competent cells of group H streptococci, strains Challis and Wicky, inhibited genetic transformation to streptomycin resistance when added to competent cultures. Antibodies against noncompetent cells did not inhibit transformation of competent cells. Strain Challis is spontaneously highly transformable. Strain Wicky is very poorly transformable but can be converted to high transformability with the exocellular competence-provoking factor (CPF) produced by strain Challis. Globulins against noncompetent cells of strain Challis and Wicky also inhibited transformation when added to noncompetent cultures prior to conversion to competence. Antibodies against cells of the related strain Blackburn, however, did not inhibit transformation under any circumstances. It is concluded that, although globulins prepared against competent cells block the deoxyribonucleic acid receptor sites present in these cells, the globulins prepared against noncompetent cells prevent conversion to competence by blocking the access of CPF to specific cellular sites for this factor. Strain Blackburn seems not to contain CPF-receptive sites and is, therefore, nontransformable.