bluuebunny/crossref_metadata_2025 huggingface dataset:
Pathogenesis of Marek's Disease in Old Chickens: Lesion Regression as the Basis for Age-Related Resistance
Authors: Sharma J. M. , Witter R. L. , Burmester B. R.
Published: January 2020

Chickens of various age levels, free from prior infection, were simultaneously exposed to Marek's disease virus, and the response of each age group was recorded. Four- and 20-week-old chickens of lines 15×7 and CM (commercial source) had substantial resistance to mortality and gross lesions. In contrast, in line 7, which was tested at 1-day, 2-, 4-, 8-, 12- and 16-week age levels, 4-week-old chickens were fully susceptible to clinical Marek's disease (MD), although resistance was demonstrated at 8-week and older age levels. Genetically resistant chickens of line 6 maintained their resistance at all age levels tested. Pathogenesis of MD was compared in 12-week-old and 1-day-old chickens of line 15×7. Within the 1-day-old group, 23% of the chickens died because of MD, whereas there were no deaths in the 12-week-old group. Both groups developed viremia although duration, incidence, and levels of virus in the 1-day-old group were higher than in the 12-week-old group. Although initially the 12-week-old group responded by producing higher levels of antibody, the long term incidence of agar gel precipitin, immunofluorescent, and virus neutralization antibody in the two groups was similar. Gross and microscopic lesions of MD developed in both groups, but lesions regressed in the 12-week-old group and persisted in the 1-day-old group. It was concluded that age resistance to MD was expressed through lesion regression.
Role of Immunity in Viral-Induced Bacterial Superinfections of the Lung
Authors: Goldstein E. , Akers T. , Prato C.
Published: January 2020

Although viral illnesses are predisposing causes for pulmonary bacterial infections, the interrelationships of viral virulence and host immunity to alterations in susceptibility to bacterial infection are incompletely understood. We used two mutant strains of encephalomyocarditis virus (minimally virulent Mengo-37A and a highly virulent Columbia SK [Col-SK]) to investigate these interrelationships. Mice that had been immunized to Mengo-37A, and nonimmunized controls, were challenged with aerosols containing 10
4
plaque-forming units of Mengo-37A or Col-SK per liter. The effect of each viral infection on pulmonary antibacterial activity was assessed 3 days later by measuring the capacity of the lungs to kill inhaled radiophosphorus (
32
P)-labeled
Staphylococcus aureus.
The degree of antibacterial dysfunction found was proportional to the virulence of the infecting virus. If the host was immune to the infecting virus, bactericidal function was not impaired by viral challenge. Neither mutant caused significant pulmonary damage; therefore: (i) viral-induced impairment in bactericidal activity reflects, quantitatively, the virulence of the virus and (ii) viral immunity protects pulmonary bacterial defenses by preventing damage to the phagocyte from the virus or its attendant metabolic abnormalities.
Isolation of a New Simian Foamy Virus from a Spider Monkey Brain Culture
Authors: Hooks John J. , Gibbs C. J. , Chou S. , Howk R. , Lewis M. , Gajdusek D. C.
Published: January 2020

A syncytium-forming (foamy) virus was isolated from a spider monkey brain cell culture. Cytopathic effect was observed both in the brain culture and in human embryonic kidney cells. Neutralizing antibody was present in the sera of the spider monkey from whom the isolation was made. The virus was inhibited by 5-bromo-2-deoxyuridine (20 μg/ml), contained a ribonucleic acid-dependent deoxyribonucleic acid polymerase, and had an infectivity peak at 1.15 g/cm
3
in a sucrose density gradient. The virus passed through a 220-nm but not a 100-nm membrane filter, was chloroform sensitive, and was inactivated at 56 C in 30 min. Hemagglutinating and hemadsorption activity was not noted with a variety of erythrocytes. The virion was spherical, formed in the cytoplasm, and was 105 to 115 nm in diameter. Ring-shaped nucleoids, 45 to 50 nm in diameter, were associated with tubular profiles. The virus was not neutralized by sera prepared against known viruses, including simian foamy virus types 1 through 7, Mason-Pfizer monkey virus, and bovine syncytial and measles viruses. Sera from a rabbit hyperimmunized with the isolate and sera from 19 spider monkeys had neutralizing antibody to the isolate; however, these sera did not cross-react with simian foamy virus types 1 through 7. Neutralizing antibody to the isolate was not detected in sera from 16 humans, 9 rhesus monkeys, and 10 chimpanzees.
Detection and Preliminary Studies on Dextranase-Producing Microorganisms from Human Dental Plaque
Authors: Staat Robert H. , Gawronski Thomas H. , Schachtele Charles F.
Published: January 2020

An enriched nutrient agar medium containing blue dextran has been utilized for the detection of dextranase-producing microorganisms in human dental plaque. When compared with the total viable anaerobic plaque flora, the proportion of these microbes in supragingival plaque from different individuals varied over a wide range. Preliminary characterization of some of the dextranase-producing microorganisms revealed a heterogeneous mixture of cell types with varying morphological and biochemical characteristics. Several bacterial isolates were tentatively identified as being members of the genus
Actinomyces.
An additional isolate appeared to belong to the genus
Bacteroides.
The dextran-degrading enzymes produced by these bacteria are extracellular, and a cell-free preparation from one of the isolates has been shown to cause extensive endohydrolytic cleavage of high-molecular-weight dextrans.
Human Serological Response to Louse-Borne Relapsing Fever
Authors: Dodge Ruth W.
Published: January 2020

Serological response to louse-borne relapsing fever in Ethiopia was determined by immobilization tests using
Borrelia recurrentis
cultures. Isolates from 26 patients tested with autologous convalescent sera showed from 90 to 100% of the organisms had been immobilized. Sera from thirteen patients were tested with autologous and heterologous strains. Several reacted with the majority and two showed high titers against all strains tested. Screening of day 2 and day 8 sera frequently showed heterologous antibody present before autologous antibody appeared, suggesting multiple antigenic challenge to infected patients. Some strains appeared to be antigenically related, but because of the wide diversity of serological responses, no definite serological groupings could be ascertained.
Filamentous Capsulated Streptococci from the Human Respiratory Tract I. Antigenic Attributes of Provisional Capsular Type 83 and Its Relationship to Streptococci of So-Called Group M
Authors: Karakawa Walter W. , Kane Judith A. , Buettger Carol , Austrian Robert
Published: January 2020

Two immunologically reactive polysaccharides have been isolated from the cell walls and from culture filtrates of a filamentous alpha-hemolytic streptococcus provisionally designated capsular type 83. Both polysaccharides were purified by diethylaminoethyl-cellulose chromatography. Analysis indicates that the capsular polysaccharide consists of galactose and phosphorus, whereas the cell wall polysaccharide contains galactosamine, glucosamine, glucose, and phosphorus. On the basis of immunochemical experiments, it is suggested that the capsular polysaccharide is composed of galactose-phosphate units with terminal galactose residues at the nonreducing end. It has also been found that the capsular antigen of streptococcus type 83 is shared by a number of streptococcal strains classified in Lancefield's group M. The cell wall polysaccharide of streptococcus type 83 cross-reacts with antibody to the C
s
, or cell wall-like capsular, polysaccharide of
Diplococcus pneumoniae
, and this cross-reactivity may be a reflection that the streptococcal antigen possesses certain structural features which are similar to those of pneumococcal C and C
s
polysaccharides.
Purification and Characterization of
Pseudomonas aeruginosa
Exotoxin
Authors: Callahan Lynn T.
Published: January 2020

A trypsin-sensitive, heat-labile exotoxin of
Pseudomonas aeruginosa
strain P-A-103 has been purified by a procedure that includes membrane ultrafiltration, hydroxylapatite chromatography, ion-exchange cellulose chromatography, and gel filtration chromatography. The procedure resulted in the recovery of 48% of the exotoxin with a 40-fold increase in specific activity (micrograms of protein per median lethal dose [LD
50
]). The mean lethal dose of the purified toxin administered intravenously into mice weighing 20 g was approximately 6 μg of protein. The toxin contained virtually no nucleic acid, detectable pigment, or lipopolysaccharide. When subjected to sodium dodecyl sulfate polyacrylamide gel electrophoresis, the toxin separated into at least six protein components which appeared to have similar molecular weights. The estimated molecular weight of the toxin is 54,000, and its isoelectric point is 5.0
Effect of Palmitic Acid Utilization on Cell Division in
Mycobacterium avium
Authors: McCarthy Charlotte
Published: January 2020

Mycobacterium avium
, a facultative pathogen for humans, undergoes a life cycle in which selected small cells elongate and then fragment to form coccobacilli.
M. avium
cells of uniform size were selected by membrane filtration and tested for growth and division in the presence or absence of palmitic acid. Growth was measured by increased cellular protein, and cell division was determined by increased colony-forming units on agar or, electronically, by increased numbers of particles. Both growth and division rates of
M. avium
were found to be dependent upon the initial concentration of palmitic acid presented to the cells. The division constant varied from 0.05 to 0.13 when the concentration of palmitic acid ranged from 0 to 175 nmol/ml of medium. With [
14
C]palmitic acid as a tracer, it was found that rapid cell division began upon cessation of fatty acid uptake. During division, new lipid materials were released which contained
14
C derived from [
14
C]palmitic acid. Limited cell division and no fragmentation occurred in fatty acid-starved cultures. During fatty acid starvation, the transparent colony form, considered a pathogen, underwent a transition to the colony form considered a nonpathogen. The possible relationships between the organism's dependence on fatty acid and its ability to infect humans are discussed.
Interferon Production by Macrophages from Adult and Newborn Rabbits Bearing Fibroma Virus-Induced Tumors
Authors: Pathak P. N. , Tompkins W. A. F.
Published: January 2020

Tumors were induced in adult and newborn rabbits by inoculation of fibroma virus. After 10 to 14 days, oil-induced peritoneal macrophages were harvested, purified, and tested in vitro for interferon synthesis after stimulation with specific and nonspecific viruses. Peritoneal macrophages from adult rabbits that had initiated tumor regression produced high levels of interferon (titers ranged from 160 to 640) after stimulation with fibroma virus, whereas macrophages from normal adult rabbits failed to produce significant levels of interferon under the same conditions (titers ranged from <10 to 10). Furthermore, fibroma-immune macrophages responded to vaccinia virus and Newcastle disease virus with higher levels of interferon than did normal macrophages. In contrast, macrophages from newborn tumor-bearing rabbits that showed no evidence of tumor regression failed to respond to fibroma virus stimulation with higher levels of interferon (titers ranged from <10 to 10). These macrophages did, however, yield significantly more interferon than newborn control macrophages when stimulated with a good interferon inducer, Newcastle disease virus (titers ranged from 10 to 80). These data suggest that interferon production may be an expression of macrophage activation to fibroma antigens and that macrophage activation is impaired in newborn rabbits with progressive growing tumors.
Viability of L-Phase Variants After Centrifugation
Authors: King James R. , McGee Zell A.
Published: January 2020

L-phase variants of several genera may be centrifuged with minimal, if any, loss of viability.
Pathogenesis and Autointerference in a Virus Disease of Crabs
Authors: Bang F. B.
Published: January 2020

The course of an infection apparently caused by a filterable virus of the blood of the shore crab.
Carcinus maenas
, has been experimentally studied in this host both at Roscoff, France. where it was originally found, and at Woods Hole, Mass., where the local species was also found susceptible. Although a portion of the infected animals die with the symptoms of inadequate blood clotting, recovery of this function occurred promptly in about two-thirds of the animals. Half of the animals that recovered this function did so within 4 to 6 days. Recovery was not accompanied by disappearance of the virus from the whole blood. In tests done as late as 40 days after recovery, virus was still present. Autointerference was demonstrated after acute infection. It was found in the serum of animals with manifest disease on all days tested and in whole blood of animals taken more than 2 days after the clotting defect appeared. It was not demonstrable within the whole blood within the first 2 days of disease. The role of this in the recovery phenomenon is discussed.
Immunity to Influenza in Ferrets X. Intranasal Immunization of Ferrets with Inactivated Influenza A Virus Vaccines
Authors: McLaren C. , Potter C. W. , Jennings R.
Published: January 2020

The response of ferrets after intranasal inoculation of inactivated A/Hong Kong/68 (H3N2) influenza virus vaccines is reported. Normal ferrets given either saline vaccine in drops or freeze-dried vaccine in an aerosol intranasally did not produce detectable serum or nasal hemagglutination inhibiting antibody and were found to be completely susceptible to challenge infection with A/Hong Kong/68 virus. Intranasal saline vaccine did not produce an additive effect on the response of ferrets simultaneously given the same vaccine intramuscularly with adjuvant. Ferrets primed by previous infection with A/PR/8/34 (H0N1) influenza virus, however, responded to intranasal immunization with saline A/Hong Kong/68 virus vaccine and produced serum and nasal antibody. These animals were found to be partially resistant to challenge infection, in contrast to similar animals given saline vaccine intramuscularly which were completely resistant to challenge infection. Primed ferrets did not respond after immunization with the freeze-dried aerosol vaccine, but this may have been due to a failure of the aerosol to be inhaled satisfactorily.
Dual Predation by Bacteriophage and
Bdellovibrio bacteriovorus
Can Eradicate
Escherichia coli
Prey in Situations where Single Predation Cannot
Authors: Hobley Laura , Summers J. Kimberley , Till Rob , Milner David S. , Atterbury Robert J. , Stroud Amy , Capeness Michael J. , Gray Stephanie , Leidenroth Andreas , Lambert Carey , Connerton Ian , Twycross Jamie , Baker Michelle , Tyson Jess , Kreft Jan-Ulrich , Sockett R. Elizabeth
Published: January 2020

With increasing levels of antibiotic resistance, the development of alternative antibacterial therapies is urgently needed. Two potential alternatives are bacteriophage and predatory bacteria. Bacteriophage therapy has been used, but prey/host specificity and the rapid acquisition of bacterial resistance to bacteriophage are practical considerations. Predatory bacteria are of interest due to their broad Gram-negative bacterial prey range and the lack of simple resistance mechanisms. Here, a bacteriophage and a strain of
Bdellovibrio bacteriovorus
, preyed side by side on a population of
E. coli
, causing a significantly greater decrease in prey numbers than either alone. Such combinatorial predator therapy may have greater potential than individual predators since prey surface changes selected for by each predator do not protect prey against the other predator.
Compounds Which Serve as the Sole Source of Carbon or Nitrogen for
Salmonella typhimurium
LT-2
Authors: Gutnick David , Calvo Joseph M. , Klopotowski Tadeusz , Ames Bruce N.
Published: January 2020

About 600 compounds were screened as possible carbon or nitrogen sources for
Salmonella typhimurium
LT-2. About 100 utilizable compounds were found.
Recognition of Altered Deoxyribonucleic Acid in Recombination
Authors: Helling Robert B.
Published: January 2020

Kinetics of inactivation of transduction by phage P1bt which had been treated with ultraviolet light (UV) or nitrous acid (NA) was examined. With
Escherichia coli
B/r (radiation-resistant), low doses of UV increased transduction frequency, but the frequency was exponentially inactivated by higher doses. Little initial stimulus was observed in strain B
s−1
(radiation-sensitive). The final rate of decay was the same as in B/r. The initial stimulus of transduction in B/r was probably a consequence of increased recombination resulting from dark repair. It was estimated that another nucleotide within 1000 nucleotide pairs had to be damaged by UV to prevent a given nucleotide from successful transduction. The NA dose response was the same for the two strains. An initial stimulus of transduction was followed by exponential decline. The UV-repair enzymes missing in B
s−1
were not required for repair of NA-induced damage to transducing or lytic phage DNA. Low recovery of new mutations in the transductants showed that mutagen-induced damage to transducing DNA was excluded from recombinant chromosomes. The few recovered mutants may have resulted from “normal” error in recombination.
Characteristics of Some Multiply Recombination-Deficient Strains of
Escherichia coli
Authors: Willetts N. S. , Clark A. J.
Published: January 2020

Strains of
Escherichia coli
have been made carrying lesions in more than one gene determining recombination. The following genotypes were constructed and verified:
recC22 recB21 recA
+
,
recC22 recB21 recA13, recC22 recB
+
recA13
, and
recC
+
recB21 recA13
. All multiple
rec
−
strains carrying
recA13
were similar to AB2463, which carries
recA13
alone, in their UV sensitivities, recombination deficiencies, and inabilities to induce lambda phage in a lysogen. However, whereas AB2463 shows a high rate of ultraviolet (UV)-induced deoxyribonucleic acid (DNA) breakdown, the multiple
rec
−
strains showed the low level characteristic of strains carrying
recC22
or
recB21
alone. The strain carrying both
recC22
and
recB21
was similar in all properties to the single mutants, suggesting that both gene products act in the same part of the recombination and UV repair pathways. It is concluded that in a Rec
+
strain, the
recA
+
product acts to inhibit DNA breakdown determined by the
recC
+
and
recB
+
products.
Suppression of Amber and Ochre Mutants in
Salmonella typhimurium
by a Mutant F′-1-
gal
Factor Carrying an Ochre Suppressor Gene
Authors: MacPhee Donald G. , Stocker Bruce A. D.
Published: January 2020

A
Salmonella typhimurium
strain was given the amber mutation
hisC527
by transduction, made galactose-negative by mutation, then infected with the F′-1-
gal
factor. Of 107 spontaneous and mutagen-induced histidine-independent mutants tested, 3 proved to result from suppressor mutations within the F′ factor. The mutant F′ factors, when transferred to
S. typhimurium
and
E. coli
auxotrophs, suppressed amber and ochre but not UGA or missense mutants, and are inferred to carry ochre suppressor genes. Attempts to isolate an F′ amber suppressor mutant were unsuccessful. A suppressor F′ factor was transferred to 14 rough mutants which had been isolated from LT2
hisC527
(amber) by selection for resistance to phage P22.c2. One rough mutant was partly suppressed, as shown by its acquisition of O agglutinability and by alterations in its phage resistance pattern. Phage P22h grown on the suppressed mutant contransduced its
rf
. gene with
cysE
+
and with
pyrE
+
, and the affected locus is inferred to be
rfaL
. Both the original and the mutant F′ factors conferred resistance to the rough-specific phage Br60, which is therefore “female-specific.”
Specificity of a Bacteriolytic Enzyme from
Pseudomonas aeruginosa
Authors: Lache Marvin , Hearn Walter R. , Zyskind Judith W. , Tipper Donald J. , Strominger Jack L.
Published: January 2020

A bacteriolytic enzyme isolated from shake-flask cultures of
Pseudomonas aeruginosa
and capable of lysing cells of
Staphylococcus aureus
was purified approximately 500-fold by passage through diethylaminoethyl cellulose and chromatography on carboxymethyl-cellulose. The purified enzyme was shown to act as an endopeptidase, cleaving the pentaglycine cross-bridges of the cell wall peptidoglycan at
d
-alanyl-glycine and glycyl-glycine linkages with the release of di−, tri−, and tetraglycine fragments. Release of NH
2
-alanine indicated weak
N
-acetylmuramyl-
l
-alanine amidase activity, but most of the residual peptide remained attached to the glycan. No hydrolysis of the glycan occurred. The lytic spectrum of the enzyme toward a variety of other cell walls of known peptidoglycan composition indicated relatively high specificity for peptidoglycans with polyglycine bridges.
Mutator Gene Studies in
Escherichia coli
Authors: Cox Edward C. , Yanofsky Charles
Published: January 2020

An
Escherichia coli
mutator gene,
mutT
, has been shown by P1-mediated crosses to map between the leucine and azide loci. The
mutT1
and
azi-r
alleles cotransduce with a frequency of >92%. In
mutT1/mutT
+
merodiploids, the
mutT1
phenotype is recessive; in
mutT1
/F′
trp
or
mutT1
/F′
lac
merodiploids, the
mutT1
allele has a
trans
effect. The gene can mutate λ and T7 phage but not T1, T3, T4, T5, and S13.
Streptolysin O: Sedimentation Coefficient and Molecular Weight Determinations
Authors: Van Epps Dennis E. , Andersen Burton R.
Published: January 2020

The sedimentation coefficient of streptolysin O as determined by sucrose density gradient ultracentrifugation is 3.7
S
. An approximate molecular weight of 60,500 was calculated from the sedimentation velocity, and a similar value was obtained by Sephadex gel filtration. There was no measurable difference in the sedimentation coefficient of streptolysin O in either the active or reversibly inactive forms, indicating that there were at most only minor conformational differences between the two forms.
Psychrophilic Properties and the Temperature Characteristic of Growth of Bacteria
Authors: Baig I. A. , Hopton J. W.
Published: January 2020

An attempt was made to define psycrophily on the basis of the temperature characteristic μ.
Ultrastructure of Dimorphic Transformation in
Paracoccidioides brasiliensis
Authors: Carbonell Luis M.
Published: January 2020

The fine structure of
Paracoccidioides brasiliensis
undergoing temperature-dependent transformation from mycelium to yeast and vice versa (M ⇌ Y) was studied. The transitional form to mycelium from the yeast appears as an elongated bud that extends from the yeast and which has a mixture of characteristics from both the yeast and the mycelium. The transitional form to yeast from the mycelium starts with enlargement of the interseptal spaces and cracking of the outer electron-dense layer of the cell wall of the hypha. Later the interseptal spaces tend to become round and separate. In M → Y only few interseptal spaces seem to transform. The yeast is produced by self-transformation of the hypha. In Y → M a new structure is formed and the yeast dies. Intrahyphal hyphae are observed during the transformation from M → Y, and intrayeast hyphae during the Y → M. Due to the high mortality and breakage observed in both types of transformations, we believe that wound of the yeast or the mycelium could elicit this phenomenon.
Reactions Involved in the Conversion of Ornithine to Proline in Clostridia
Authors: Costilow Ralph N. , Laycock Loretta
Published: January 2020

An enzyme system which converts ornithine to proline was partially purified from extracts of cells of
Clostridium botulinum
and of
Clostridium
PA 3670 by fractionation with ammonium sulfate and by dialysis in the presence of 0.01
m
ornithine. Nicotinamide adenine dinucleotide (NAD) was the only cofactor required for maximal activity of the partially purified system. A possible intermediate in the conversion was accumulated when a high concentration of proline was used as substrate and the NAD was maintained in the oxidized state by adding lactic dehydrogenase. Small but significant amounts of this or a similar compound were trapped with either ornithine or proline as substrate when
o
-aminobenzaldehyde was added to reaction mixtures. The accumulation of the
o
-aminobenzaldehyde reaction product was NAD-dependent with both substrates. The compound accumulated from proline was identified as Δ
1
-pyrroline-5-carboxylic acid on the basis of the melting point of the 2,4-dinitrophenylhydrazone, and by paper chromatography of the reaction product formed with
o
-aminobenzaldehyde. Also, extracts of
C. botulinum
cells oxidized reduced NAD (NADH) in the presence of the product from proline or in the presence of Δ
1
-pyrroline-5-carboxylic acid, but did not do so in the presence of the other possible intermediate, Δ
1
-pyrroline-2-carboxylic acid.
14
C-Δ
1
-pyrroline-5-carboxylic acid was reduced to
14
C-proline by these extracts in the presence of NADH. These data indicate that the conversion of ornithine to proline by
C. botulinum
and
Clostridium
PA 3679 cells involves an oxidation of ornithine to glutamic-γ-semialdehyde which undergoes ring closure to Δ
1
-pyrroline-5-carboxylic acid. The latter compound is then reduced to proline.
Deoxyribonucleic Acid Characterization of Bdellovibrios
Authors: Seidler Ramon J. , Starr Mortimer P. , Mandel M.
Published: January 2020

The guanine plus cytosine (GC) content of the deoxyribonucleic acid (DNA) of 11 isolates of host-dependent (H-D) bdellovibrios and 18 host-independent (H-I) derivatives was determined from thermal denaturation curves and buoyant densities in CsCl. The H-D and respective H-I cultures have GC contents which are identical within the limits of experimental error. Most cultures of
Bdellovibrio bacteriovorus
, including the holotype culture, have 50.4 ± 0.9 moles% GC in their DNA; two bdellovibrio isolates of presently uncertain nomenclatural status contain DNA of about 43% GC. Optical melting profiles of all the DNA from all of these organisms are particularly steep, indicating little compositional heterogeneity. Chromatography of acid hydrolysates of
Bdellovibrio
nucleic acids reveal no unusual components. The DNA content per cell of one H-I derivative is about one-third the amount per
Escherichia coli
cell growing at a comparable rate.
Bacterial Interference with L-Forms
Authors: Boris Marvin , Teubner Diane , Shinefield Henry
Published: January 2020

During the course of studying the effect of normal nasal flora on the growth of L-forms, a clear zone of inhibition was observed around colonies of many coagulase-negative staphylococci. Subsequent investigation demonstrated thatStaphylococcus aureusand someS. albusstrains produce a substance which is capable of markedly inhibiting the growth of stable staphylococcal and streptococcal L-forms. This interfering substance is separable from the staphylococcal organism and is diffusible through 1.5% agar, but not through a dialysis membrane. It is heat-stable.
Sensitivity and Resistance to Spectinomycin in
Escherichia coli
Authors: Anderson Porter
Published: January 2020

Inhibition of growth and division of
Escherichia coli
by spectinomycin is reversible, and the kinetics of its interference with deoxyribonucleic and ribonucleic acid synthesis may be interpreted as secondary effects of inhibition of protein synthesis on the ribosome. Spontaneous mutations to spectinomycin resistance occur in
E. coli
K-12 at a rate of about 2 × 10
−10
. Resistance is transducible with a discrete lag in phenotypic expression, and the kinetics of its development is about the same as that for streptomycin resistance. All spectinomycin-resistant mutants tested contain resistant ribosomes, and all map in a locus (
spc
) counterclockwise to and 70% cotransducible with the classical
str
locus. Differences in the residual drug sensitivity of various spectinomycin-resistant mutants, and of their ribosomes, indicate the existence of more than one phenotypic class of resistance.
Technique for the Isolation of Ribonucleic Acid-Rich Mutants from
Escherichia coli
Authors: MacDonald R. E.
Published: January 2020

A technique for the isolation of ribonucleic acid (RNA)-rich mutants of
Escherichia coli
is described. Mutagenized cells were centrifuged to isopycnic equilibrium on potassium tartrate or cesium sulfate gradients. Samples from the region of the gradients slightly denser than the majority of the cells were spread on agar plates, and the resulting clones were tested for increased RNA to protein ratios.
Cholera Toxins: Immunogenicity of the Rabbit Ileal Loop Toxin and Related Antigens
Authors: Kaur Jasbir , Burrows William , Cercavski Lora
Published: January 2020

A method of assay of immunogenic potency of the cholera gut toxin is described; it is based on the relation of dose of antigen to neutralizing antibody titer produced in the rabbit under defined conditions and allows quantification of immunogenicity as immunogenic units per milligram of protein. Evidence, based on immunogenicity and rabbit ileal loop toxicity, is presented which indicates that the positively charged fraction of liquid-culture supernatant fluid eluted in deionized water from diethylaminoethyl Sephadex, or in electrolyte from carboxymethyl Sephadex, is a complex made up of a nonantigenic toxic moiety, a nontoxic protein component which elicits the formation of toxin-neutralizing antibody, and an inactive fraction. The complex may also be dissociated in high-salt concentrations with apparent recombination of the toxic moiety with a nondialyzable constituent of peptone to give a negatively charged complex. The immunogenic component is found in nontoxic supernatant fluids of cultures grown at
p
H 6.5 or in media deficient in peptone. It is also present in the nontoxic fraction eluted from diethylaminoethyl Sephadex in electrolyte or in deionized water from carboxymethyl Sephadex. When separated from the positively charged toxic moiety, the net charge of the antigen is reduced as shown by immunoelectrophoresis. On primary fractionation, the antigen may be associated with a minor antigenic component of the negatively charged complex containing a major antigen eliciting vibriocidal antibody formation, but antisera to the toxin antigen preparations, either in this form or freed of antigenic contamination by recycling, do not contain vibriocidal antibody. It is suggested that this antigen be designated the T (toxin) antigen, and the antigen producing vibriocidal antibody the V antigen. These two antigens would appear to represent the major antigenic specificities associated with the antitoxic and antibacterial elements of the immune response to infection.
Method for Fingerprinting Yeast Cell Wall Mannans
Authors: Kocourek Jan , Ballou Clinton E.
Published: January 2020

Controlled acetolysis of yeast mannans yields mixtures of oligosaccharides with (1→2) and (1→3) linkages between the mannose units, whereas the less stable (1→6) linkages of the polysaccharide backbone are cleaved. The “fingerprints,” obtained by gel filtration of the oligosaccharide mixtures, can be used to distinguish between the different yeast mannans. The general method may be useful for determining the taxonomy of yeasts and for making correlations between immunochemical reactivity and mannan structure.
Effect of
p
H on In Vitro Phagocytosis of
Streptococcus pyogenes
Authors: Beck A. , Bergner-Rabinowitz Sonia , Ofek I.
Published: January 2020

Phagocytosis experiments were performed with mouse peritoneal leucocytes (MPL). The natural
p
H of the mouse peritoneal cavity was found to be between 6.1 and 6.3. The phagocytic and intracellular killing activities of MPL by
p
H variations was studied. It was observed that the optimal ingestion and intracellular killing of bacteria is at the natural
p
H of the peritoneal cavity.
Characterization and Relatedness of Marine Vibrios Pathogenic to Fish: Deoxyribonucleic Acid Homology and Base Composition
Authors: Kiehn E. D. , Pacha R. E.
Published: January 2020

Deoxyribonucleic acid (DNA) isolated from several pathogenic marine vibrios was utilized in studies of base composition and nucleotide sequence relationships. Patterns of relatedness inferred from DNA criteria were found to correlate closely with those inferred from morphological, physiological, and serological analysis of the same organisms. The utility of the phenotypic and genotypic approaches to the determination of relatedness is discussed.
Initial Characterization of a Temperature-Sensitive Rod
−
Mutant of
Bacillus subtilis
Authors: Boylan Robert J. , Mendelson Neil H.
Published: January 2020

The general biological properties of a temperature-sensitive morphological mutant of
Bacillus subtilis
(168ts–200B) are described. At the restrictive temperature (45 C), cells grow as spheres which divide irregularly to form grapelike clusters. At the permissive temperature (30 C), the mutant grows as typical
B. subtilis
rods in short chains. A log-phase culture of rods (30 C) may be converted to spheres by transfer to 45 C. Reversion of spheres to rods occurs when the alternate temperature shift is made. Growth curves, deoxyribonucleic acid replication kinetics, and the morphology of mutant 168ts–200B are described.
Requirement for Coenzyme A in the Phosphoroclastic Reaction of Anaerobic Bacteria
Authors: Hespell R. B. , Joseph R. , Mortlock R. P.
Published: January 2020

Various bacteria which degrade pyruvate by the phosphoroclastic reaction were examined with respect to the role of coenzyme A (CoA) in this reaction. The strictly anaerobic bacteria, which cleave pyruvate by the phosphoroclastic reaction characteristic of
Clostridia
, required catalytic levels of CoA for the CO
2
-pyruvate exchange and acetoin-forming portions of the phosphoroclastic reaction. These reactions were reversibly inhibited by the CoA analogue, desulfo-CoA. In contrast, using cell-free extracts of bacteria which degrade pyruvate by the coliform phosphoroclastic reaction (pyruvate formate-lyase), no requirement for CoA could be observed for the formate-pyruvate exchange reaction. It is suggested that CoA serves a regulatory function in the early portion of the clostridal type of phosphoroclastic reaction.
Regulation of Penicillinase Synthesis: Evidence for a Unified Model
Authors: Imsande John
Published: January 2020

The kinetics of penicillinase induction in
Bacillus cereus
569 was investigated. An increase in the rate of penicillinase synthesis was demonstrated within 30 sec of the addition of inducer (benzylpenicillin); however, the maximum induced rate of penicillinase synthesis was not attained until at least 30 min after the addition of inducer. In contrast to earlier claims, a quantitative estimate showed that the penicillinase messenger ribonucleic acid (mRNA) half-life is approximately 2 min. These findings strongly suggest that the rate of synthesis of penicillinase mRNA increases continuously during most of the 30-min latent period. A model for the regulation of penicillinase synthesis in three gram-positive organisms is presented which is consistent with a nondiffusible inducer, a short-lived mRNA, a relatively long latent period (i.e., an apparently slow inactivation of penicillinase repressor), and the existence of at least two regulatory genes.
Three-Dimensional Morphology, Ultrastructure, and Replication of
Mycoplasma felis
Authors: Boatman Edwin S. , Kenny George E.
Published: January 2020

The morphology and replication of
Mycoplasma felis
in relation to growth phase in culture were studied by electron microscopy. The organisms showed 1.0 to 1.45-hr doubling times with typical bacterial-type growth curves when grown in dialysate broth supplemented with horse serum. Organisms were fixed for electron microscopy by using Veronal acetate-buffered 0.8% OsO
4
(
p
H 6.1) in 20% sucrose. The morphology of exponential-phase organisms differed markedly from that of stationary or death-phase organisms, which were essentially large round forms with either dispersed or abnormally aggregated cytoplasm. Plasticine models prepared from serial sections of organisms in exponential phase showed the organisms to be either disc-shaped, triangular, horseshoe-shaped, or multilobular. A central “hole” was frequently present in these structures and could be visualized in the lobular forms as an interconnecting circular membrane. The inner surface of this membrane often showed contact with a small membranous body about 0.12 μm in diameter. The significance of this body is unknown. The morphology of the various shapes was confirmed by using the phosphotungstic acid and critical point methods. When the ratios of the various forms in exponential-phase cultures were determined, it was found that a replication sequence could be proposed which accounted for not only the volume increase required to accommodate deoxyribonucleic acid (DNA) replication but also the distribution of that DNA. Although it is likely that DNA replication in
M. felis
is a binary process, it appears that the mechanism for production of new cells need not be a binary process.
Localization of the β-Glucosidases in
Neurospora crassa
Authors: Eberhart Bruce M. , Beck Reta S.
Published: January 2020

The β-glucosidases (EC 3.2.1.21) of
Neurospora crassa
were studied with respect to their location in conidia and young mycelia. Aryl-β-glucosidase of conidia was nearly equally divided between extracellular and bound activity. Bound aryl-β-glucosidase was almost all available to substrate. An induction procedure was used to maximize both β-glucosidases in 4 to 6-hr cells. Aryl-β-glucosidase was entirely bound but still mostly (90%) detectable, whereas cellobiase was mostly internal and cryptic. A freeze-thaw cycle or treatment with phenethyl alcohol or deoxycholic acid made the cellobiase detectable without releasing it from the cell. A 10 to 20% increase in cell-bound aryl-β-glucosidase could be obtained by this treatment. Dilute HCl (0.1
n
) destroyed the patent aryl-β-glucosidase but not the cryptic aryl-β-glucosidase or the cryptic cellobiase activity in intact cells. This suggested that most aryl-β-glucosidase activity was exterior to the cell membrane but still within the mural space. The thermal stability of patent aryl-β-glucosidase and released cellobiase was found to be higher than in corresponding cell-free extracts. Measurements of
K
m
suggested a slightly lower affinity for substrate
p
-nitrophenyl-β-
d
-glucopyranoside by the enzymes in intact cells compared to enzymes in extracts.
Lipid Composition of
Bacillus cereus
During Growth and Sporulation
Authors: Lang Dennis R. , Lundgren D. G.
Published: January 2020

The lipid composition of
Bacillus cereus
during growth and sporulation was examined. The total lipid extract accounted for 2 to 3% of the dry weight of the cells and consisted of neutral lipids (30 to 40%) and phospholipids (60 to 70%). Phospholipids were separated by thin-layer chromatography into eight components; phosphatidyl ethanolamine, phosphatidyl glycerol, and diphosphatidyl glycerol were the major phospholipids and accounted for over 90% of the total. Also identified was a diglycosyl diglyceride and an alanine ester of phosphatidyl glycerol. Diphosphatidyl glycerol was more difficult to extract than the other components in vegetative and stationary-phase cells, but became increasingly easy to extract during spore maturation, and during sporulation cellular levels increased. Phosphatidyl glycerol had a high turnover rate; it accounted for about 70% of the phospholipid synthesis throughout sporulation but only represented between 30 and 40% of the total phospholipid at any time. Phosphatidyl ethanolamine, on the other hand, accounted for about 20% of the synthesis but was the major phospholipid (50 to 60% of the total).
Thermostable Aldolase from
Thermus aquaticus
Authors: Freeze Hudson , Brock Thomas D.
Published: January 2020

Data are presented on the purification and properties of the thermostable fructose-1,6-diphosphate aldolase of
Thermus aquaticus
, a nonsporulating, extreme thermophile. The enzyme shows little activity at temperatures below 60 C and optimal activity at about 95 C. The enzyme was purified 43-fold by diethylaminoethyl cellulose column chromatography and Sephadex G-200 gel filtration. The enzyme is activated by high concentrations of NH
4
+
and low concentrations of Fe
2+
and Co
2+
and is strongly inhibited by ethylenediaminetetraacetic acid (EDTA). The activation by Fe
2+
and Co
2+
and the inhibition by EDTA are both reversed by dialysis. The enzyme is greatly activated by cysteine and less so by other sulfhydryl compounds. Activation by cysteine is reversible by dialysis. The purified enzyme had a molecular weight as determined by Sephadex G-200 gel filtration of 140,000; after incubation of enzyme with cysteine, another molecular species was also found with a molecular weight of 70,000. The purified enzyme is stable at low protein concentrations to 97 C but is rapidly inactivated at 105 C. In cysteine the enzyme is more heat labile; heat inactivation in the presence of cysteine is prevented by substrate, although, in the absence of cysteine, substrate partially labilizes the enzyme to heat. The temperature optimum for enzyme activity is several degrees lower in the presence of cysteine than in its absence, and the

K
m

is threefold lower. It is concluded that the
T. aquaticus
enzyme resembles some other aldolases of Rutter's class II, except for its extreme heat stability. The
T. aquaticus
enzyme is compared with that of
Bacillus stearothermophilus
, a moderate thermophile. Although the
T. aquaticus
enzyme is considerably more heat stable, the enzymes from the two thermophiles have many similarities. New data are presented which show that the
B. stearothermophilus
aldolase is metal ion-dependent, in disagreement with earlier reports.
Filamentous Growth of
Mucor rouxii
Under Nitrogen
Authors: Elmer Gary W. , Nickerson Walter J.
Published: January 2020

The form of growth of
Mucor rouxii
(National Regional Research Laboratory 1894) under nitrogen is dependent on inoculum size. With a large inoculum (10
6
spores inoculated per ml), the morphology consists mainly of swollen spores with some filaments and yeastlike cells. At lower inoculum levels growth is filamentous. The morphology of this strain on incubation under nitrogen and the dependence of the form of growth on inoculum size are similar to those found previously for other strains of
M. rouxii
.
Use of
33
P as an Indicator for
32
P Pulse Labeling of Nucleic Acids in Bacterial Cultures
Authors: Jordan B.
Published: January 2020

33
P-phosphate can be used to follow bacterial phosphorus consumption before
32
P pulse labeling.
Role of Glycogen in Survival of
Streptococcus mitis
Authors: Van Houte J. , Jansen H. M.
Published: January 2020

Evidence has been obtained which indicates that the possession of glycogen by
Streptococcus mitis
favors its survival during starvation.
Polyribosomes from
Bacillus subtilis
During Amino Acid Starvation in the Presence and in the Absence of Actinomycin
Authors: Barlati Sergio
Published: January 2020

Polysomes were extracted from
Bacillus subtilis
cells starved for a required amino acid. The monosome peak appeared soon after starvation; no difference in the rate of degradation was detected when the cells were starved for arginine or tryptophan in a double auxotroph. RNA production during starvation was not inhibited by actinomycin, but the molecular weight of the product made in the presence of the antibiotic was much lower. Indications that stable messenger ribonucleic acid is present for up to 90 min after amino acid starvation are also presented.
Relative Affinity of Vancomycin and Ristocetin for Cell Walls and Uridine Diphosphate-
N
-Acetylmuramyl Pentapeptide
Authors: Best Gary K. , Grastie Miriam K. , McConnell Robert D.
Published: January 2020

A determination of the relative affinity of vancomycin and ristocetin for isolated cell walls and for a peptidoglycan precursor was made. These antibiotics had previously been shown to adsorb to cell walls and to complex with peptides containing a
d
-alanyl-
d
-alanine C-terminus. By using
14
C-uridine diphosphate (UDP)-
N
-acetylmuramyl pentapeptide, it was shown that the complex which is formed between this peptidoglycan precursor and either vancomycin or ristocetin does not preclude adsorption of the antibiotics to cell walls of
Micrococcus lysodeikticus
. Complex formation between ristocetin and UDP-
N
-acetylmuramyl pentapeptide was assured by differential absorption spectra. However, when the complex was mixed with cell walls, the antibiotic was sedimented with the walls, and the radioactivity remained in the supernatant solution. This indication that ristocetin and vancomycin have a greater affinity for walls than for UDP-
N
-acetylmuramyl pentapeptide and that the complex per se does not bind to cell walls suggests that adsorption of these antibiotics to cell walls is probably responsible for the inhibition of peptidoglycan synthesis. This proposal is strengthened by the observation that complexed antibiotic is no less inhibitory for growth of
Bacillus subtilis
than free vancomycin or ristocetin.
Chemical Composition of the Cell Wall of the H37Ra Strain of
Mycobacterium tuberculosis
Authors: Acharya P. V. Narasimh , Goldman Dexter S.
Published: January 2020

The cell wall of the H37Ra strain of
Mycobacterium tuberculosis
was isolated and freed of extraneous noncovalently linked material by a series of extraction and enzymatic procedures. Chemical analysis of the cell wall has revealed the following composition: 22.8% amino acids, principally alanine, glutamate, and diaminopimelate in a molar ratio of 1:1.8:0.8; 24.7% reducing sugars, all in the form of arabinose and galactose in a molar ratio of 2.6:1; and 3.95% amino sugars, all in the form of glucosamine, muramic acid, and galactosamine in a molar ratio of 1:6.6:0.8. About 32.1% of the dry weight of the cell wall is lipid, of this about 55% is in the form of two series of mycolic acids. Each series of mycolic acids contains two homologues differing by 28 mass units. One pair of homologues contains in each a carbonyl function and an unsaturated double bond; the other pair contains two cyclopropane groups in each homologue. The remaining lipids are composed principally of normal saturated fatty acids, including tuberculostearic acid.
Biosynthesis of the Branched-Chain Amino Acids in Yeast: a Leucine-Binding Component and Regulation of Leucine Uptake
Authors: Bussey Howard , Umbarger H. E.
Published: January 2020

Use of an ion-exchange resin assay has shown that leucine is bound to a component of a dialyzed extract of yeast. Leucine binding may be related to in vivo uptake of the amino acid. A yeast strain with a 30-fold lower affinity for leucine uptake in vivo has a parallel reduction in affinity for in vitro leucine binding; the rate of leucine uptake in wild-type yeast can be increased four- to fivefold by growth on leucine as a sole nitrogen source. Under these conditions, the specific activity of the leucine-binding component also increases over threefold. Regulation of leucine uptake was studied by using wild-type strain 60615 and a mutant 60615/fl
2
with a constitutively elevated leucine uptake system. Leucine pool formation in the mutant was accompanied by an overshoot, leading to a loss of leucine from the pool. The phenomenon could be observed in the wild type under certain conditions. The mechanism of this process was examined. The leucine uptake system was found to be stable in the absence of protein synthesis. The rate of leucine uptake increased on reduction of the pool of amino acids, and in strain 60615/fl
2
the ability to overshoot was rapidly recovered on depletion of the leucine pool. The results suggest a control of leucine uptake by feedback inhibition, in which leucine or other amino acids, e.g., isoleucine, inhibit leucine uptake. The results do not exclude control by a rapidly activated-inactivated system.