bluuebunny/crossref_metadata_2025 huggingface dataset:
Sucrose Catabolism in
Clostridium pasteurianum
and Its Relation to N
2
Fixation
Authors: Daesch Geraldine , Mortenson Leonard E.
Published: January 2020

The growth constant and Y (sucrose) (grams of cells per mole of sucrose) for NH
3
-grown cultures of
Clostridium pasteurianum
were 1.7 times those of N
2
-grown cultures, whereas the rate of sucrose utilized per gram of cells per hour was similar for both conditions. The Y (sucrose) of chemostat cultures grown on limiting NH
3
under argon at generation times equal to those of N
2
-fixing cultures was less than that of cultures grown on excess NH
3
, but cells of NH
3
-limited cultures contained the N
2
-fixing system in high concentration. The concentration of the N
2
-fixing system in whole cells, when measured with adenosine triphosphate (ATP) nonlimiting, was more than twofold greater than the amount needed for the N
2
actually fixed. Thus, energy production from sucrose, and not the concentration of the N
2
-fixing system nor the maximal rate at which N
2
could be fixed, was the limiting factor for growth of N
2
-fixing cells. Either NH
3
or some product of NH
3
metabolism partially regulated the rate of sucrose metabolism since, when cultures fixing N
2
, growing on NH
3
, or growing on limiting NH
3
in the absence of N
2
were deprived of their nitrogen source, the rate of sucrose catabplism decreased. Calculations showed that the rate of ATP production was the growth rate-limiting factor in cells grown on N
2
, and that the increased sucrose requirement of N
2
-fixing cultures in part reflected the energy demand of N
2
fixation. Calculations indicated that whole cells require about 20 moles of ATP for the fixation of 1 mole of N
2
to 2 moles of NH
3
.
Listeria monocytogenes
L Forms I. Induction, Maintenance, and Biological Characteristics
Authors: Edman David C. , Pollock Mary B. , Hall Elizabeth R.
Published: January 2020

L forms were induced from 15 of 16 strains of
Listeria monocytogenes
on penicillin gradient plates incubated under aerobic conditions. The culture medium for maintenance of these L forms must contain an electrolyte in a concentration of 1% or sucrose in a concentration of 10%. The electrolytes NaCl, KCl, or MgSO
4
were used in both induction and maintenance media. Induction of L forms occurred more rapidly on media containing KCl.
Listeria
L forms had the same fermentation reactions as the parent bacterium. The L-form growth in liquid medium was slow, not extensive, and appeared as clumps on the bottom of culture tubes. The morphology of
Listeria
L forms was similar to that reported for other bacterial L forms. The L forms derived from strain 10403, serotype 1, were stable after two or more passages on penicillin media. They did not revert to the bacterial form after 40 subcultures on penicillin-free media. Some L-form colonies derived from strain 10403 did revert to the bacterial form when transferred directly from induction plates to penicillin-free media. Studies of the growth characteristics for L forms derived from strain 10403 gave the following results: an optimal temperature of 30 C, high electrolyte or sucrose concentration necessary for induction and maintenance, and no requirement for serum.
Mutants of
Aerobacter aerogenes
Capable of Utilizing Xylitol as a Novel Carbon
Authors: Wu T. T. , Lin E. C. C. , Tanaka S.
Published: January 2020

Wild-type
Aerobacter aerogenes
1033 is unable to utilize xylitol. A succession of mutants was isolated capable of growth on this compound (0.2%) at progressively faster rates. Whereas the ability to utilize xylitol was achieved in the first-stage mutant (X1) by constitutive production of ribitol dehydrogenase (for which xylitol is a substrate but not an inducer), the basis for enhanced utilization of xylitol in the second-stage mutant (X2) was an alteration of ribitol dehydrogenase. This enzyme was purified from the various mutants. The apparent
K
m
for xylitol was 0.12
m
with X2 enzyme and 0.29
m
with X1 enzyme. The X2 enzyme was also less heat stable and, at 0.05
m
substrate concentration, had a higher ratio of activity with xylitol compared to ribitol than did the X1 enzyme. The third mutant (X3), with an even faster growth rate on xylitol, produced a ribitol dehydrogenase indistinguishable physically or kinetically from that of X2. However, X3 produced constitutively an active transport system which accepts xylitol. The usual function of this system is apparently for the transport of
d
-arabitol since the latter is not only a substrate but also an inducer of the transport system in parental strains of X3. The sequence of mutations described herein illustrates how genes belonging to different metabolic systems can be mobilized to serve a new biochemical pathway.
Enzyme Pattern and Aerobic Growth of
Saccharomyces cerevisiae
Under Various Degrees of Glucose Limitation
Authors: Beck Christoph , Von Meyenburg H. Kaspar
Published: January 2020

The enzyme pattern of
Saccharomyces cerevisiae
was followed during batch growth and in continuous culture in a synthetic medium limited for glucose under aerobic conditions. Seven enzymes were measured: succinate-cytochrome
c
oxidoreductase, malate dehydrogenase, nicotinamide adenine dinucleotide-linked glutamate dehydrogenase, malate synthase, isocitrate lyase, aldolase, and nicotinamide adenine dinucleotide phosphate (NADP
+
)-linked glutamate dehydrogenase. During fermentation of glucose and high growth rate (μ) during the first log phase in batch experiments, the first five enzymes (group I) were repressed, and aldolase and NADP
+
-linked glutamate dehydrogenase (group II) were derepressed. During growth on the accumulated ethyl alcohol and lower μ, the group I enzymes were preferentially formed and the other two were repressed. A sequence of derepression of the group I enzymes was found during the shift from glucose to ethyl alcohol metabolism, which can be correlated with a strong increase in the percentage of single (nonbudding) cells in the population. A correlation between the state of cells in the budding cycle and enzyme repression and derepression is suggested. In continuous culture, the enzyme pattern was shown to be related to the growth rate. The group I enzymes were repressed at high growth rates, while the group II enzymes were derepressed. Each enzyme exhibits a different dependence. The enzyme pattern is shown to depend on the rate of substrate consumption as well as on the type of metabolism and to be correlated with the budding cycle. The enzyme pattern is considered to be controlled by changes of intracellular catabolic or metabolic conditions inherent in the division cycle.
Deoxyribonucleic Acid Base Composition of the Genus
Lactobacillus
Authors: Gasser Francis , Mandel Manley
Published: January 2020

Deoxyribonucleic acids of 45 strains of
Lactobacillus
and 5 strains of
Bifidobacterium
which had been analyzed for base composition by chromatographic means were examined at equilibrium in a CsCl density gradient. Regression analysis showed that there have been systematic errors involved in the estimation of guanine plus cytosine (GC) content by the chemical method, and that the relation between buoyant density and base composition is indeed linear and best fitted by the equation GC = 10.309 (ρ−1.662), which compares well in slope with the equation of Schildkraut, Marmur, and Doty. With the improved data obtained in this study, the specific groupings of the species of both genera were reevaluated.
d-Amino Acid Oxidase Induction in the Kidneys of Germ-free Mice
Authors: Lyle L. R. , Jutila J. W.
Published: January 2020

High levels ofd-amino acid oxidase activity were found in the kidneys of conventionally reared mice, whereas the enzyme was absent from the kidneys of most germ-free mice. Injection ofd-alanine or monocontamination withBacillus cereusstimulatedd-amino acid oxidase activity in the kidneys of germ-free mice.
Immunological Homology Between Crystal and Spore Protein of
Bacillus thuringiensis
Authors: Delafield F. P. , Somerville H. J. , Rittenberg S. C.
Published: January 2020

Spore suspensions containing about 0.3% crystals and crystal suspensions containing about 0.1% spores were obtained from cultures of
Bacillus thuringiensis
by extraction with a two-phase system. Both preparations were tested for the presence of contaminating material from vegetative cells and were judged to be clean. Solutions of spore protein were obtained by extracting broken spores with phosphate buffer followed by extraction with either alkali- or urea-mercaptoethanol. The alkali spore or urea spore extracts had the same isoelectric point as crystal protein solubilized with these reagents. An antiserum prepared against alkali crystal solution precipitated alkali or urea spore extracts and crystal solutions but not phosphate spore extracts or extracts of whole cells. Lines of identity between spore and crystal precipitates were observed by using the Ouchterlony double-diffusion technique. Absorption of the antiserum with an excess of urea spore extract caused a disappearance of the precipitin bands originating from the spore protein and the homologous bands from the crystal protein. The results suggest that the crystal and endospore contain one or more common proteins.
Osmotic Fragility and Viability of Lysostaphin-induced Staphylococcal Spheroplasts
Authors: Schuhardt V. T. , Klesius Phillip H.
Published: January 2020

When
Staphylococcus aureus
FDA 209P cells were treated with lysostaphin (1 unit/ml) in hypertonic sodium chloride or sucrose environments, viable, osmotically fragile spheroplasts were produced. Turbidimetric studies indicated that 64% (w/v) sucrose or 20 to 28% (w/v) sodium chloride gives maximal protection against lysis of the lysostaphin-treated cells. The NaCl appeared to give greater protection than the sucrose and proved to be much more suitable for viability and related studies. Viability of both shocked and nonshocked treated cells was determined by
S. aureus
colony counts on agar plates overlayered with the test dilution of the cells suspended in 4 ml of semisolid agar containing 72% sucrose. The difference in the counts represented the number of revertible spheroplasts. Under these conditions, 30 to 50% of the test cells were recovered as osmotically fragile, but revertible, spheroplasts after 5 to 10 min of exposure to lysostaphin in 24% NaCl. This rewere obtained after 5 to 10 min of exposure to lysostaphin in 24% NaCl. This recovery rate fell off rapidly with prolonged exposure. In view of residual turbidity of 30- and even 60-min exposure preparations, it appeared probable that most of the osmotically fragile cells were eventually converted to protoplasts by the prolonged lysostaphin treatment. Osmotically fragile cells were converted to osmotic stability by fixation with 4% (v/v) Formalin.
Depressed Cellular Formation of Antibody toShigellaAntigens In Vitro by Spleen Cell Cultures from Unresponsive Mice
Authors: Friedman Herman
Published: January 2020

Specific antibody plaque-forming cells (PFC) toShigella-soluble antigen did not appear in spleen cell cultures fromShigella-tolerant mice, as occurred with similar cultures prepared from normal mice immunized withShigellaantigen prior to sacrifice. Cultures from tolerant mice also failed to form serologically detectable amounts of agglutinins in vitro. Exposure of cell cultures from tolerant mice in vitro to additional antigen had little or no effect on appearance of plaque-forming cells toShigella. Spleen cells from normal control mice formed readily detectable levels of antibody, as well as specific antibody plaque-forming cells, after similar stimulation with antigen either in vivo or in vitro. The absence of antibody-forming cells in cultures prepared from spleens of tolerant mice was specific since such cultures, as well as those from normal control mice, formed numerous antibody plaques to unsensitized sheep erythrocytes in vitro after in vivo challenge of the mice with sheep erythrocytes. Tolerance toShigellaantigen, as assessed by absence of antibody-forming cells in vitro, persisted for several months. Spleen cell cultures from tolerant mice less than 3 to 4 months of age did not form significant numbers of antibody plaques, even after in vitro exposure to specific antigen. However, spleen cultures prepared from neonatally treated mice, approximately 6 to 8 months old, formed essentially normal numbers of specific PFC in vitro, indicating that the animals had “recovered” from tolerance and that their lymphoid cells were capable of responding toShigellaantigen in vitro. Absence of specific PFC in cell cultures from tolerant animals supports the concept that tolerance is due to a central failure of specific immunocompetent cells and not due to an inhibitory effect caused by either “excess” antigen or humoral antibody.
Ribosomal Complexes from an Extremely Halophilic Bacterium and the Role of Cations
Authors: Rauser W. E. , Bayley S. T.
Published: January 2020

Concentrated extracts of
Halobacterium cutirubrum
were prepared at 0 C by gently disrupting cells with a nonionic detergent in a medium containing 3.0
m
KCl, 0.5
m
NH
4
Cl, and 0.04
m
(or more) magnesium acetate and then treating the gelatinous mass with deoxyribonuclease. On KCl-sucrose gradients containing 0.5
m
NH
4
Cl and 0.04
m
magnesium acetate, these extracts showed 30
S
and 50
S
ribosomal subunits plus a flat profile of faster-sedimenting material up to high
S
values. Only after frozen storage or brief incubation of the extract were 70
S
ribosomes and distinct classes of small polyribosomes detected. Digestion with ribonuclease converted faster-sedimenting material to 70
S
particles. The presence of chloramphenicol during preparation of the extracts did not affect these results. The evidence suggests that ribosomal particles exist in these cells as subunits or as polyribosomes but not as 70
S
ribosomes. To investigate the function of Mg
++
and NH
4
+
ions in ribosomal complexes from this halophile, concentrated cell extracts and extracts incubated with
14
C-leucine were examined on KCl-sucrose gradients containing different concentrations of these ions. Polyribosomes and the bulk of 70
S
ribosomes dissociated reversibly to subunits at about 0.01
m
Mg
++
, whereas a small fraction of the 70
S
particles, including those which in vitro incorporated
14
C-leucine into nascent protein, dissociated only below 1 m
m
Mg
++
. Below this concentration of Mg
++
, nascent protein remained attached to the 50
S
subunit even at 0.04 m
m
Mg
++
in the presence of 0.35 to 0.5
m
NH
4
Cl. Nascent protein, presumably as peptidyl-transfer ribonucleic acid, dissociated reversibly from 50
S
subunits only at 0.04 m
m
Mg
++
and 0.1
m
or less NH
4
+
. Thus, the stability of polyribosomes from
H. cutirubrum
depends specifically on both Mg
++
and NH
4
+
ions.
Bactericidal Action of Fresh Rabbit Blood Against
Brucella abortus
Authors: Joos Richard W. , Hall Wendell H.
Published: January 2020

A photometric method was used to measure the bactericidal kinetics for
Brucella abortus
of freshly drawn rabbit blood during the time before clotting. This antibrucellar activity varied between rabbits in different immunologic states. Nonimmunized rabbits had moderate bactericidal activity after a lag of about 2 min. The blood of some immunized rabbits gave an immediate and strong kill, but in certain other immunized rabbits, especially when hyperimmunized, the bactericidal activity was inhibited. It appeared that serum bactericidins and complement are sometimes as active in unclotted blood as they are in serum. However, this bactericidal activity can be either increased or neutralized by immunization. The prozone bactericidal inhibition phenomenon (Neisser-Wechsberg) found in immune serum may, in fact, reflect inhibition taking place in vivo. Inhibition of the bactericidal activity in blood can contribute to the persistence of chronic infections and individual variations in resistance.
Surface Antigens of Smooth Brucellae
Authors: Diaz Ramon , Jones Lois M. , Leong Daniel , Wilson J. B.
Published: January 2020

Surface antigens of smooth brucellae were extracted by ether-water, phenol-water, trichloroacetic acid, and saline and examined by immunoelectrophoresis and gel diffusion with antisera from infected and immunized rabbits. Ether-water extracts ofBrucella melitensiscontained a lipopolysaccharide protein component, which was specific for the surface of smooth brucellae and was correlated with the M agglutinogen of Wilson and Miles, a polysaccharide protein component devoid of lipid which was not restricted to the surface of smooth brucellae and was not correlated with the smooth agglutinogen (component 1), and several protein components which were associated with internal antigens of rough and smooth brucellae. Immunoelectrophoretic analysis of ether-water extracts ofB. abortusrevealed only two components, a lipopolysaccharide protein component, which was correlated with the A agglutinogen, and component 1. Component 1 fromB. melitensisandB. abortusshowed identity in gel diffusion tests, whereas component M fromB. melitensisand component A fromB. abortusshowed partial identity with unabsorbed antisera and no cross-reactions with monospecific sera. Attempts to prepare monospecific sera directly by immunization of rabbits with cell walls or ether-water extracts were unsuccessful. Absorption of antisera with heavy fraction of ether-water extracts did not always result in monospecific sera. It was concluded (as has been described before) that the A and M antigens are present on a single antigenic complex, in different proportions depending upon the species and biotype, and that this component is a lipopolysaccharide protein complex of high molecular weight that diffuses poorly through agar gel. Components 1, A, and M were also demonstrated in trichloroacetic acid and phenol-water extracts. With all extracts,B. melitensisantigen showed greater diffusibility in agar thanB. abortusantigens. After mild acid hydrolysis,B. abortusether-water extract was able to diffuse more readily.
Transport of Aminophosphonic Acids in
Lactobacillus plantarum
and
Streptococcus faecalis
Authors: Holden Joseph T. , Van Balgooy Josephus N. A. , Kittredge James S.
Published: January 2020

Aminophosphonic acids analogous to glutamic acid, aspartic acid, alanine, and valine were actively accumulated by
Lactobacillus plantarum
. Uptake was dependent on the availability of glucose and, in all cases, the estimated intracellular concentrations substantially exceeded extracellular levels. During uptake, there was little metabolism of tritiated 2-amino-3-phosphonopropionic acid (APP), the aspartic acid analogue, and a negligible incorporation of isotope from this substance into the nucleic acid, lipid, protein, or cell wall fractions of the cell. Competition studies with APP indicated that its transport in
L. plantarum
and in
Streptococcus faecalis
was antagonized only by structurally related compounds such as glutamic, aspartic, and cysteic acids. Kinetic studies showed that APP was taken up by a single catalytic system in
S. faecalis
. A mutant strain of this organism which lacks one of two kinetically distinguishable dicarboxylic amino acid transport systems failed to accumulate measurable amounts of APP. These experiments indicate that the aminophosphonic acids are accumulated by the amino acid transport systems in these bacteria with minimal metabolic changes.
Modification of Selected Host-reactive Properties of Endotoxin by Treatment with Sodium Deoxycholate
Authors: Tarmina D. F. , Milner K. C. , Ribi E. , Rudbach J. A.
Published: January 2020

Endotoxin dissociated into subunits by sodium deoxycholate treatment exhibited diminished capacity to kill chick embryos, protect mice against the lethal effects of infection with
Salmonella typhi
, evoke hemorrhagic necrosis in skin inoculated with epinephrine, prepare for and provoke the dermal Shwartzman reaction, and induce pyrogenic tolerance. Surfactant-treated material which had been allowed to reaggregate displayed activity equivalent to that of untreated material. These findings were consistent with the working hypothesis that a macromolecular complex of critical size is required in order for endotoxin to elicit its characteristic effects in the host.
Trehalose Phosphate Synthesis in
Streptomyces hygroscopicus:
Purification of Guanosine Diphosphate
d
-Glucose:
d
-Glucose-6-Phosphate 1-Glucosyl-Transferase
Authors: Elbein Alan D.
Published: January 2020

Guanosine diphosphate
d
-glucose:
d
-glucose-6-phosphate 1-glucosyl-transferase was purified approximately 100-fold from extracts of
Streptomyces hygroscopicus
. The purified enzyme catalyzed the transfer of glucose from guanosine diphosphate-
d
-glucose to glucose-6-phosphate to form trehalose phosphate and guanosine diphosphate. The enzyme was specific for these two substrates and was stimulated by the addition of magnesium ions. The product was characterized as α-α-trehalose-6-phosphate by its physical and chemical properties. The enzyme was present in a large number of
Streptomyces
species, suggesting that this group of organisms synthesized trehalose phosphate in a unique manner. This enzyme was not detected in fungi, since these organisms utilized uridine diphosphate-
d
-glucose as the glucosyl donor.
Genetic Integration in the Heterospecific Transformation of
Haemophilus influenzae
Cells by
Haemophilus parainfluenzae
Deoxyribonucleic Acid
Authors: Steinhart William L. , Herriott Roger M.
Published: January 2020

The in vivo chemical linkage of
Haemophilus parainfluenzae
deoxyribonucleic acid (DNA) with the
H. influenzae
genome has been found to occur at a much higher level than is suggested by the low efficiency of the heterospecific transformation of an antibiotic resistance marker. This linkage, about 60% of the level with homospecific DNA, was found to involve alkali-stable bonding. The amount of host DNA label released (about 60%) was about the same as that released during homospecific transformation. Also, over 60% of the
H. influenzae
cells adsorbing
H. parainfluenzae
DNA could not form colonies upon plating. This lethality of the heterospecific transformation was not immediate but followed considerable metabolic activity of the host cells. These data are presented to show that the “limited-pairing” hypothesis may be only a partial explanation for the low efficiency of heterospecific transformation. Another hypothesis is presented which takes into account the lethal effect of this kind of transformation.
Interference Contrast and Phase Contrast Microscopy of Sporulation and Germination of
Bacillus megaterium
Authors: Hitchins Anthony D. , Kahn Arnold J. , Slepecky Ralph A.
Published: January 2020

The techniques of Nomarski interference contrast microscopy and phase-contrast microscopy were compared for their utility in monitoring sporulation and germination in
Bacillus megaterium
. The Nomarski technique permitted rapid and easy delineation of septation and engulfment during sporulation, whereas with phase contrast microscopy these stages were not detected at all. The later stages of sporulation were easily seen by either technique. Thus, of the seven stages of sporulation as recognized by the electron microscopy of thin sections, five can now be routinely detected quantitatively by optical microscopy: septation (stage II), engulfment (stage III), phase-dark forespore (corresponding to cortex formation, stage IV), phase-bright spore in a sporangium (corresponding to coat formation, stage V), and the free spore (stage VII). This means that now only stage I (axial filament) and stage VI (maturation of the refractile spore) require electron microscopy for routine detection. There was no advantage in using Nomarski optics for germination studies.
Relationship of Route of Inoculation and Nature of Toxin Preparation to Bioassay ofClostridium perfringensα-Toxin in Mice
Authors: Lynch Kenneth L. , Moskowitz Merwin
Published: January 2020

The toxicity ofClostridium perfringenswas determined in mice utilizing three different routes of inoculation. There was marked variation in the minimum lethal dose with the different routes; the largest amount was required for the intracutaneous route, less for the intravenous route, and least with the intraperitoneal route. The relationship of toxicity to the lecithinase content of different toxin preparations was assayed. It was found that the toxicity of toxin preparations in different states of purification was not correlated with their lecithinase content.
Effect of Immunosuppressive Agents on Normal Phage-neutralizing Antibody in the Mouse
Authors: Karp R. D. , Bradley S. G.
Published: January 2020

The actions of three immunosuppressive drugs on normal antibody synthesis in the adult mouse were determined. Inbred mice were given daily intraperitoneal injections of actinomycin D, uracil mustard, or cyclophosphamide for extended periods. The sera of treated and untreated mice were assayed for phage-neutralizing activity to monitor the effect of each drug on the amount of circulating normal antibody. Except for an initial decrease in titer of normal anti-phage MSP2 activity, actinomycin D had no significant effect on normal antibody activity. Uracil mustard caused alternating elevation and depression of normal antibody titers. Cyclophosphamide caused a prolonged depression of normal antibody. The response patterns to the three immunosuppressive agents were the same for both induced and normal antibody.
Preparation and Description of High-Molecular-Weight Soluble Surface Antigens from a Group AStreptococcus
Authors: Besdine Richard W. , Pine Leo
Published: January 2020

High-molecular-weight proteins having M protein reactivity were isolated without acid or alkaline digestion. Treatment of a heat-killed group AStreptococcuswith sonic vibration released antigens which reacted strongly and specifically with absorbed type-specific antiserum. This antigen preparation was released without diminishing the total yield of acid-extractable M protein of the original heat-killed cells. Fractionation of the sonic preparation on a sucrose gradient yielded four peaks of M reactivity. When these fractions were placed on Sephadex G-200 columns, the M reactive material of three fractions appeared in the void volumes, suggesting that the active material in each had a molecular weight greater than 300,000. The reactivity of the fourth fraction followed closely the void volume of Sephadex G-100. Chemical analysis revealed heterogeneity of the fractions. Spectral analysis showed virtual absence of nucleic acid in three of the fractions and a moderate amount in the fourth. Bactericidal inhibition tests showed activity of three of the four fractions. Analysis of the fractions by Ouchterlony double-diffusion technique revealed that each of the four fractions had several antigenic constituents. All four contained M antigen. T antigen and a third unnamed antigen were present in some of the fractions. Group reactivity was present in all fractions, but did not reside on the M molecule. The enhanced potential of sonically released antigens to induce high-titer specific precipitating antibodies to M protein is discussed.
Two Mechanisms of Allelic Complementation Among Tryptophan Synthetase Mutants of
Saccharomyces cerevisiae
Authors: Duntze Wolfgang , Manney Thomas R.
Published: January 2020

Two different types of allelic complementation were observed in tryptophan synthetase mutants of the yeast
Saccharomyces cerevisiae
. Each type is associated with a different mechanism for the enzymatic conversion of indole-3-glycerol phosphate (InGP) to tryptophan. Mechanism I is utilized by a hybrid tryptophan synthetase that resembles, but is not identical with, the wild-type enzyme. Mechanism II is due to a sequential conversion of InGP to free indole, and indole to tryptophan. Two partially active mutant enzymes rather than a single hybrid enzyme catalyze the sequential reaction steps. This is an example of intracellular cross-feeding. The quantitative evaluation of mechanism II leads to the conclusion that tryptophan synthetase in yeast is most likely a dimer of two identical subunits.
Metabolism of β-Methylaspartate by a Pseudomonad
Authors: Sebek O. K. , Barker H. A.
Published: January 2020

A bacterium was isolated from soil which utilizes
threo
-β-methyl-
l
-aspartate, certain other amino acids, and a variety of organic substances as single energy sources. It is, or closely resembles,
Pseudomonas putida
biotype B. The ability of this organism to rapidly decompose such amino acids is dependent on inducible enzyme systems. Dialyzed cell-free extracts of this bacterium metabolize β-methylaspartate only when catalytic amounts of α-ketoglutarate, or pyruvate, and pyridoxal phosphate are also present. The main products formed from β-methylaspartate under these conditions are α-aminobutyrate, carbon dioxide, and α-ketobutyrate. When
l
-aspartate is substituted for β-methylaspartate in this system, it is converted mainly to alanine and carbon dioxide. β-Methyloxalacetate is decarboxylated, and the resulting α-ketobutyrate is converted enzymatically in the presence of glutamate to α-aminobutyrate which accumulates. The added keto acids are converted, in part, to the corresponding amino acids probably by transamination. The data indicate that β-methylaspartate is converted to α-aminobutyrate, and aspartate to alanine, by a circuitous transamination-β-decarboxylation-transamination sequence rather than by a direct β-decarboxylation.
Gratuitous Synthesis of β-Lactamase in
Staphylococcus aureus
Authors: Leggate John , Holms William H.
Published: January 2020

The synthesis of β-lactamase in response to 2-(2′-carboxyphenyl)-benzoyl-6-aminopenicillanic acid as inducer was studied in
Staphylococcus aureus
. The inducer was not detectably hydrolyzed by β-lactamase and had minimal antibacterial activity. The kinetics of induction showed a lag of 4 to 6 min in a nutrient broth medium and 8 to 12 min in a defined medium, followed by constant differential rates of synthesis of β-lactamase. The differential rate of β-lactamase synthesis in nutrient broth was unaltered by supplementing the medium with glucose, galactose, lactose, arabinose, glycerol, or sucrose. Variations in the partial pressure of oxygen did not alter the differential rate of synthesis of β-lactamase over the range 18 to 50% oxygen in nitrogen. Even when the rate of growth was considerably reduced by high-oxygen tension, the differential rate of synthesis of the enzyme remained the same. The differential rate of β-lactamase synthesis at low inducer concentration increased after a shift down in growth rate. The effect was observed with several inducers and under different nutritional conditions, but was always preceded by a change in growth rate. It is suggested that the change in growth rate itself causes the increase in differential rate of β-lactamase synthesis.
Specificity of Acquired Resistance Produced by Immunization with Mycobacterial Cells and Mycobacterial Fractions
Authors: Coppel Suzanne , Youmans Guy P.
Published: January 2020

Mice were immunized intraperitoneally with 5.0 mg of living and 5.0 mg of heat-killed H37Ra cells of the attenuated strainMycobacterium tuberculosisand challenged intraperitoneally withListeria monocytogenesandKlebsiella pneumoniae. The period of protection provided by the living and heat-killed H37Ra cells against both heterologous infections was the same. When mice were immunized intraperitoneally with graded doses of living and heat-killed H37Ra and challenged intraperitoneally with listeria or klebsiella, the lowest immunizing dose providing protection against both klebsiella and listeria challenge was the same for living and heat-killed cells. Living and heat-killed cells also immunized equally effectively when the routes of immunization and challenge were different. Mice also were immunized intraperitoneally with mycobacterial ribosomal fraction, mycobacterial cell walls, and several nonspecific agents (Escherichia coliendotoxin, mineral oil emulsion, and Freund's incomplete adjuvant). The mice were challenged intraperitoneally with listeria or klebsiella at varying times after immunization. The mycobacterial components and all the nonspecific agents provided transitory protection lasting no longer than 4 days after immunization. Only the mycobacterial cell walls and the endotoxin provided protection against listeria challenge. It was concluded that the protection provided by the mycobacterial ribosomal fraction is specific for tuberculosis infection, since this fraction provided no protection against listeria infection and only transitory protection against klebsiella. It was also concluded that the mycobacterial component providing protection against heterologous infections is heat stable and probably is found in the cell wall.
Heat-sensitive Step in Deoxyribonucleic Acidmediated Transformation of
Bacillus subtilis
Authors: McCarthy Charlotte , Nester Eugene W.
Published: January 2020

Over 90% of the competent cells in a population of
Bacillus subtilis
lost their competence after being heated to 50 C for 5 min. There was only a slight loss in the number of transformants if the culture was heated for 5 min after the termination of transformation, but 90% of the transformants were lost after 1 hr at 50 C. The population as a whole grew at a slightly faster rate at 50 C than at 32 C. We postulate that a heat-labile factor is required for the uptake or retention (or both) of deoxyribonucleic acid (DNA) in the cell, since uptake of
32
P-DNA into a deoxyribonuclease-resistant form was inversely proportional to the time of exposure to heat. Cells that had lost competence after being heated did not regain their competence for at least several hours, although other cells in the population became competent. These data suggest that the heat-labile factor required for competence is synthesized only once during the period that a cell remains competent.
Transport of Donor Deoxyribonucleic Acid into the Cell Interior of Thymine-starved
Bacillus subtilis
with Chromosomes Arrested at the Terminus
Authors: Archer Luis J. , Landman Otto E.
Published: January 2020

The chromosomes of a tryptophan
−
, thymine
−
double auxotroph of
Bacillus subtilis
were uniformly aligned at the chromosome terminus by an amino acid starvation treatment. By subsequent incubations, the starved culture was rendered competent, while its state of synchronous chromosome arrest was maintained by thymine starvation. The competent, chromosome-arrested cells were transformed for three unlinked markers, located in two different chromosome regions. Shortly after addition of deoxyribonucleic acid, the cell walls were removed with lysozyme in a medium containing deoxyribonuclease and no thymine, and the protoplasted culture was assayed for single and double transformants. It was found that markers both near and distant from the terminus entered freely into the cell interior. There was no important difference in the relative frequency of entry of different markers between synchronously arrested cells and nonsynchronized control cultures. It is concluded that entry of a given marker into the cell interior can occur even if the replication site of the chromosome is stationary at a location distant from the locus of the resident homolog of the entering marker. A mechanism of donor deoxyribonucleic acid entry involving homology at the replication fork is excluded.
Transductional Analysis of
Pseudomonas aeruginosa
Methionineless Auxotrophs
Authors: Calhoun D. H. , Feary T. W.
Published: January 2020

Seventy-one methionineless and cysteineless auxotrophs of
Pseudomonas aeruginosa
were placed into nine groups on the basis of their growth on methionine precursors and the cross-feeding response. Transduction experiments with bacteriophage F116 indicated the presence of four linkage groups among the methionineless mutants and at least three among the cysteineless mutants. These studies suggested that the biosynthesis of methionine in
P. aeruginosa
is similar to that described in other microorganisms, although none of the mutants lacking the ability to methylate homocysteine grew with vitamin B
12
or
S
-adenosylmethionine.
Effect of Galactose on β-Galactosidase Synthesis in
Escherichia coli
K-12
Authors: Llanes Barbara , McFall Elizabeth
Published: January 2020

In wild-type strains of
Escherichia coli
K-12, the rate of thiomethylgalactoside (TMG)-induced β-galactosidase synthesis is decreased in the presence of galactose or glucose. A spontaneous mutant of a K-12 strain, 58-161, which synthesizes β-galactosidase at a low rate was isolated. In this mutant, galactose, after a lag of about one generation time, evoked the same final differential rate of enzyme synthesis as did the gratuitous inducer TMG. However, constitutive, TMG-induced and galactose-induced synthesis in the mutant were subject to inhibition by exogenous glucose. It is concluded that repression of β-galactosidase synthesis derived from glucose is distinct from the inhibition derived from galactose.
Immunological Studies on Dermatophytes IV. Chemical Structures and Serological Reactivities of Polysaccharides from
Microsporum praecox, Trichophyton ferrugineum, Trichophyton sabouraudii
, and
Trichophyton tonsurans
Authors: Grappel Sarah F. , Blank F. , Bishop C. T.
Published: January 2020

The chemical structures and serological specificities of polysaccharides isolated from four species of dermatophytes,
Microsporum praecox, Trichophyton ferrugineum, T. sabouraudii
, and
T. tonsurans
, were investigated. Each of these species yielded a mixture of crude polysaccharides which could be separated into three water-soluble, neutral polysaccharides free of nitrogen. These were grouped as galactomannan I, galactomannan II, and glucan. The galactomannans I were quite similar in chemical structure. When measured by complement fixation, their serological cross-reactivities were similar with rabbit antisera to each of these species except
T. sabouraudii
. The differences in their relative reactivities with this antiserum could be correlated with differences in structure and specificity of this antiserum for galactofuranose end groups. The galactomannans II differed both in chemical structure and in their serological reactivities with antisera to each of these species. The galactomannan II from
T. ferrugineum
differed most in chemical structure and was the least reactive serologically. The glucans also differed in both structure and serological reactivities.
Inducible Degradation of Hydroxyproline in
Pseudomonas putida:
Pathway Regulation and Hydroxyproline Uptake
Authors: Gryder Rosa M. , Adams Elijah
Published: January 2020

Studies in
Pseudomonas putida
of the inducible degradation of hydroxyproline to α-ketoglutarate have indicated that either of the two epimers, hydroxy-
l
-proline or allohydroxy-
d
-proline, acts as an inducer of all the pathway enzymes. In a mutant lacking the first enzyme of the sequence, hydroxyproline-2-epimerase, which interconverts these two hydroxyproline epimers, either epimer is still equally active as an inducer of the remaining three enzymes, suggesting that each epimer has intrinsic inducer activity. The second and third enzymes of the sequence were induced coordinately. The induction process appeared to be insensitive to catabolite repression under a number of experimental conditions. The induced enzymes were stable even under conditions of nitrogen starvation and other conditions designed to increase protein turnover. In addition to inducing the degradative enzymes, the two hydroxyproline epimers were also found to induce an uptake system that concentrates hydroxyproline intracellularly. Either amino acid induced the uptake system for its epimer as well as for itself.
Genetic and Regulatory Aspects of Methionine Biosynthesis in
Saccharomyces cerevisiae
Authors: Cherest H. , Eichler F. , de Robichon-Szulmajster H.
Published: January 2020

Methionine biosynthesis and regulation of four enzymatic steps involved in this pathway were studied in
Saccharomyces cerevisiae
, in relation to genes concerned with resistance to ethionine (
eth
1
and
eth
2
). Data presented in this paper and others favor a scheme which excludes cystathionine as an obligatory intermediate. Kinetic data are presented for homocysteine synthetase [K
m
(
O
-acetyl-
l
-homoserine) = 7 × 10
−3
m
;
K
i
(
l
-methionine) = 1.9 × 10
−3
m
]. Enzymes catalyzing steps 3, 4, 5, and 9 were repressible by methionine. Enzyme 4 (homoserine-
O
-transacetylase) and enzyme 9 (homocysteine synthetase) were simultaneously derepressed in strains carrying the mutant allele
eth
2
r
. Studies on diploid strains confirmed the dominance of the eth
2
s
allele over eth
2
r
. Regulation of enzyme 3 (homoserine dehydrogenase) and enzyme 5 (adenosine triphosphate sulfurylase) is not modified by the allele eth
2
r
. The other gene
eth
1
did not appear to participate in regulation of these four steps. Gene enzyme relationship was determined for three of the four steps studied (steps 3, 4, and 9). The structural genes concerned with the steps which are under the control of
eth
2
(
met
8
: enzyme 9 and
met
a
: enzyme 4) segregate independently, and are unlinked to
eth
2
. These results are compatible with the idea that the gene
eth
2
is responsible for the synthesis of a pleiotropic methionine repressor and suggest the existence of at least two different methionine repressors in
S. cerevisiae
. Implications of these findings in general regulatory mechanisms have been discussed.
Fractionation and Characterization of the Plasma and Mesosome Membrane of
Listeria monocytogenes
Authors: Ghosh B. K. , Murray R. G. E.
Published: January 2020

Protoplasts of
Listeria monocytogenes
strain 42 were fractionated after control lysis on a Ficoll (a polysucrose) density gradient. Visually, five zones could be recognized in the gradient. The first one was composed of amorphous cytoplasmic solutes (fraction 1a) and a mixture of particles (fraction 1b). These were: (i) light particles that were lipase-sensitive and composed of six subunits and (ii) heavy particles, sensitive to ribonuclease and devoid of fine structure. The second zone consisted of tubules and vesicles still harboring cytoplasmic components (fraction 2), whereas the third zone contained only empty vesicles and protoplast ghosts (fraction 3). The material congregating into the fourth zone was morphologically identical to that of the third (fraction 3a). The fifth and heaviest zone contained a mixture of (i) particles without any substructure and (ii) partly lysed protoplasts (fraction 4). Fractions 1b and 4 were the richest in nucleic acids (ribonucleic acid, 11.4 and 9.4%, respectively; deoxyribonucleic acid, 5.1 and 4.8%, respectively), whereas fraction 1b had the highest protein contents (74.6%). Phospholipids were mainly found in fractions 2 and 3. Except for fraction 1, all materials contained significant amounts of protein-bound phosphorus. The main concentrations of four enzymes were: glucose-6-phosphate dehydrogenase (fraction 1a); adenosine triphosphatase and reduced nicotinamide adenine diphosphate oxidase (fraction 3); nitro blue tetrazolium chloride reductase (fraction 2). Fractionation of strain 42 after addition of
32
P during the mid-log phase of growth revealed that the radio-activity was mainly detected in fraction 1b, when growth in the presence of the marker was allowed for 10 min, and in fraction 2, when growth was allowed for 90 min. The vesicles of fraction 2, often tubular, are probably of mesosomal origin, whereas those of fraction 3, which are always spherical, represent, most likely, the bulk of the cell plasma membrane. Our data showed slight chemical differences between these two fractions, but the differences in enzymatic activities and lipid-phosphorus incorporation during long pulse experiments were most dramatic.
Regulation of Enzyme Synthesis in the Aromatic Amino Acid Pathway of
Bacillus subtilus
Authors: Nester Eugene W. , Jensen Roy A. , Nasser DeLill S.
Published: January 2020

The control of the synthesis of certain key enzymes of aromatic amino acid biosynthesis was studied. Tyrosine represses the first enzyme of the 3-deoxy-
d
-
arabino
heptulosonic acid 7-phosphate pathway, DAHP synthetase, as well as shikimate kinase and chorismate mutase about fivefold in cultures grown under conditions limiting the synthesis of the aromatic amino acids. A mixture of tyrosine and phenylalanine represses twofold further. Tryptophan does not appear to be involved in the control of these enzymes. The specific activity of at least one early enzyme, dehydroquinase, remains essentially constant under a variety of nutritional supplementations. Two enzymes in the terminal branches are repressed by the amino acids they help to synthesize: prephenate dehydrogenase can be repressed fourfold by tyrosine, and anthranilate synthetase can be repressed over 200-fold by tryptophan. There is no evidence that phenylalanine represses prephenate dehydratase. Regulatory mutants have been isolated in which various enzymes of the pathway are no longer repressible. One class is derepressed for several of the prechorismate enzymes, as well as chorismate mutase and prephenate dehydrogenase. In another mutant, several enzymes of tryptophan biosynthesis are no longer repressible. Thus, the rate of synthesis of enzymes at every stage of the pathway is under control of various aromatic amino acids. Tyrosine and phenylalanine control the synthesis of enzymes involved in the synthesis of the three aromatic amino acids. Each terminal branch is under the control of its end product.
Identification of Closely Linked Loci Controlling Ultraviolet Sensitivity and Refractivity to Colicin E2 in
Escherichia coli
Authors: Holland I. B. , Threlfall E. J.
Published: January 2020

Mutants (phenotypic symbol Ref-II) refractory to colicin E2 have been isolated in several strains of
Escherichia coli
K-12, and a
ref
II locus has been mapped 1 to 2 min counter clockwise to
thr
. A small number of Ref-II mutants are also ultraviolet (UV)-sensitive and the
uv
s
locus in one such strain has been mapped close to the
ref
II locus near
thr
. The Ref-II mutation alone does not affect recombinant formation in F
−
strains, but the Ref-II, UV
s
strains behave in many respects like Rec
−
mutants, giving reduced recombination frequencies in crosses with male strains. It is suggested that the
ref
II and
uv
s
loci correspond to closely linked if not identical genes, concerned in some way in the activity of one or more deoxyribonucleases, and that the Ref-II, UV
s
mutants arise as the pleiotropic expression of a single gene or of a deletion or polar mutation affecting linked genes.
In Vitro and In Vivo Activity of Hamycin Against
Blastomyces dermatitidis
Authors: Shadomy Smith , Robertson Giles M. , Shadomy H. Jean , Utz John P. , Gamble Elaine
Published: January 2020

Clinical responses of patients with blastomycosis to treatment with hamycin have been variable. An explanation for this was sought in a series of studies in which in vitro and in vivo susceptibilities to hamycin of five strains of
Blastomyces dermatitidis
were compared. Minimal inhibitory concentrations of hamycin for the five strains indicated uniformly high levels of in vitro susceptibility (0.008 to 0.016 μg/ml). In vivo activity was measured in infected mice treated intraperitoneally for a period of 28 days with doses of the drug ranging from 0.001 to 0.030 mg per mouse. Significant differences in response to treatment among the five strains were noted (
P
< 0.001), and protective doses were found to vary from 0.001 to >0.030 mg per mouse per day. Further observations of infected mice after treatment revealed marked rates of relapsing infection, and several strains caused death. Persistent inapparent infections were also detected on culture of selected organs. Toxicity due to hamycin alone was not observed. These results suggest that variations in clinical responses to hamycin therapy in treatment of blastomycosis reflect differences in pathogenesis and host response in vivo to the infecting organism rather than differences in susceptibility of
B. dermatitidis
to hamycin.