bluuebunny/crossref_metadata_2025 huggingface dataset:
Ribonucleic Acid Synthesis During Morphogenesis in
Myxococcus xanthus
Authors: Bacon Karen , Rosenberg Eugene
Published: January 2020

Ribonucleic acid synthesis was measured during the morphogenesis of
Myxococcus xanthus
. After induction of microcyst formation by the addition of glycerol to an exponential culture, net ribonucleic acid (RNA) synthesis was immediately terminated (measured either chemically or by the accumulation of acid-insoluble radioactivity). Extensive RNA turnover did take place, however, including RNA made both before and after induction. Sucrose gradient centrifugation revealed that ribosomes and ribosomal RNA were synthesized during microcyst formation even though there was no net RNA synthesis. Base analyses of the total RNA of vegetative cells and 120-min microcysts were indistinguishable.
Biotin-deficient Growth of
Bacillus polymyxa
Authors: Summers Jesse W. , Wyss Orville
Published: January 2020

When
Bacillus polymyxa
, a wild-type biotin auxotroph, is grown in biotin-deficient medium, a retardation of cell division and consequential cell elongation are the initial detectable consequences of limited biotin. Subsequent events in biotin-deficient cells include, in chronological order: inhibition of net ribonucleic acid (RNA) synthesis and a simultaneous arithmetical accumulation of protein; loss of net RNA, deoxyribonucleic acid, and protein synthesis; morphological aberration, death, and lysis. Incorporation studies employing
32
P-phosphate and
14
CO
2
demonstrate an initial selective inhibition of net ribosomal RNA synthesis over that of ribosomal protein or total protein. Biotin could not be replaced by various extracts from which biotin had been removed, nor could osmotic stabilizers be found which could prevent lysis of the culture.
Numerical Data Concerning the Sensitivity of Anaerobic Bacteria to Oxygen
Authors: Fredette V. , Planté C. , Roy A.
Published: January 2020

Upon comparison of results obtained from growing eight different species of anaerobic bacteria in deep agar under two and three atm of pure oxygen with results of growing them in air under atomospheric pressure, it appears possible that the old terms of “microaerophobic,” “very strict anaerobe,” and “microaerophilic” can be replaced by precise values corresponding to the size of the inhibition zone produced by oxygen under various pressures when the bacteria are grown in a solid medium. The simultaneous effect of the dilution of the inoculum and the pressure of oxygen used was determined with the help of an electronic computer according to the standard multiple regression method. Two indices have been worked out which express the sensitivity of the species at different oxygen pressures when varying numbers of anaerobic bacteria are used:Xsp, which is the size in millimeters of the inhibition zone when 1:10 dilutions of the culture are grown under pure oxygen at atmospheric pressure (lp=0), andBsp, which is the result of multiplying by 1.43 the difference in size of inhibition zone when 1:10 dilutions of the culture are grown under atmospheric air (lp = −0.7) and under pure oxygen at 1 atm absolute.
Somatic Antigen 2 Inheritance in
Salmonella
Groups B and D
Authors: Johnson E. M.
Published: January 2020

Somatic (O) antigen 2 of
Salmonella paratyphi A
replaced somatic antigen 4 of an
S. typhimurium
recipient as the consequence of mating with an
S. paratyphi A
var.
durazzo
Hfr strain. The genetic determinants of these O antigens behaved in this cross as alleles of a common O locus, which is linked to the determinant of histidine biosynthesis,
his
. By employing phage lysates obtained by growth of P22 on an
S. typhimurium
hybrid which had received
his
and O-factor 2 determinants from the
S. paratyphi
A Hfr, it was possible to cotransduce the
his
and O-antigen 2 genes to both
S. typhimurium
and
S. typhosa. S. typhimurium
transductants which received somatic antigen 2 concurrently lost O-antigen 4, and
S. typhosa
transductants receiving O-antigen 2, lost their native O-antigen 9. These results indicate that the genetic determinants of O-antigens 2, 4, and 9 occupy the same O locus in
S. paratyphi
A,
S. typhimurium
, and
S. typhosa
, respectively, and are probably allelic.
Streptomyces steffisburgensis
sp.n
Authors: Dietz Alma
Published: January 2020

Streptomyces steffisburgensis
is described as a new species and named to conform with the 1966 International Code of Nomenclature of Bacteria. The description of the organism is accompanied by a color print of it on six agar media and electron micrographs of the spore chains.
Fine Structure and Location of the Mycoplasma-like Gray Lung and Rat Pneumonia Agents In Infected Mouse Lung
Authors: Gay Frederick W.
Published: January 2020

The mycoplasma-like gray lung and rat pneumonia agents were indistinguishable in fine structure and location in infected mouse lung. Both agents resembled mycoplasmas in fine structure, being bounded by a 110 A unit membrane which enclosed an internal region of 20 to 30 A branching fibrils and groups of 120 A ribosomes. They differed from mycoplasmas in having an 80 to 90 A electron-lucent space separating the unit membrane from the internal material, and the internal region was bounded by a 30 to 40 A unbranched fibril. In division, the organisms appeared to form a transverse trilayered “division plate.” In overall shape, the organisms seemed to be thick circular or oval plates, and they tended to lie in palisade arrangement on cell surfaces. Both agents were free in large numbers in the alveoli and respiratory bronchioles, and on the surface of intro-alveolar mononuclear cells, but were not seemingly associated with lung cells as such. Intracellular organisms were within membrane-bounded inclusions.
Inhibition of Oxygen Utilization and Destruction of Ubiquinone by Ultraviolet Irradiation of
Thiobacillus thiooxidans
Authors: Adair Frank W.
Published: January 2020

Ultraviolet (UV) irradiation inhibited sulfur oxidation by cells of
Thiobacillus thiooxidans
. Sulfur-oxidizing activity decreased as the exposure time to UV light increased. A loss of the ability of cells of fix CO
2
paralleled the loss of sulfur-oxidizing activity. UV light photoinactivated ubiquinone purified from
T. thiooxidans
. The same percentage of sulfur-oxidizing activity and ubiquinone was destroyed after 15 min of UV exposure. Both the photoinactivation of sulfur oxidation and ubiquinone followed first-order reaction kinetics. The specific rate constants for both photoinactivations were nearly equal. Cells completely inactivated by UV light contained no ubiquinone. Ubiquinone was found to be a component of the cell wall-membrane complex.
Salinity Effect on the Maximal Growth Temperature of Some Bacteria Isolated from Marine Environments
Authors: Stanley Simon O. , Morita Richard Y.
Published: January 2020

Salinity of the growth medium was found to have a marked effect on the maximal growth temperature of four bacteria isolated from marine sources.
Vibrio marinus
MP-1 had a maximal growth temperature of 21.2 C at a salinity of 35% and a maximal growth temperature of 10.5 C at a salinity of 7%, the lowest salinity at which it would grow. This effect was shown to be due to the presence of various cations in the medium. The order of effectiveness of cations in restoring the normal maximal growth temperature, when added to dilute seawater, was Na
+
> Li
+
> Mg
++
> K
+
> Rb
+
> NH
4
+
. The anions tested, with the exception of SO
4
=, had no marked effect on the maximal growth temperature response. In a completely defined medium, the highest maximal growth temperature was 20.0 C at 0.40
m
NaCl. A decrease in the maximal growth temperature was observed at both low and high concentrations of NaCl.
Comparative Regulation of Isoenzymic 3-Deoxy-
d
-
arabino
-Heptulosonate 7-Phosphate Synthetases in Microorganisms
Authors: Jensen Roy A. , Nasser Delill S.
Published: January 2020

The independent control of regulatory isoenzymes by different metabolites constitutes one well-known pattern of control in branched metabolic pathways. This pattern was previously found to be widely distributed in the aromatic amino acid pathway of microorganisms in the case of the first enzyme of the sequence, 3-deoxy-
d
-
arabino
-heptulosonate 7-phosphate (DAHP) synthetase. The comparative stability of the isoenzymes as well as the effect of aromatic amino acids in the growth medium upon the levels of the individual isoenzymes were shown for
Salmonella typhimurium
. Several lines of evidence are discussed to demonstrate the strong reliance of
Escherichia coli
upon the phenylalanine-sensitive isoenzyme for the ordinary biosynthetic needs of wild-type strains. The frequent occurrence of “dominant” isoenzyme species which resist repressive effects of the inhibitory end products was noted. The lack of an obligatory correlation of the level of an isoenzyme activity and the synthesis of the end product which specifically controls its activity is used to discount the possibility that each isoenzyme might feed a unique and separate metabolic pool of end-product precursor. An isoenzymic DAHP synthetase sensitive to feedback inhibition by low levels of tryptophan was fractionated from tyrosine- and phenylalanine-sensitive isoenzymes in cell-free extracts of
Neurospora crassa
.
Cryptococcus neoformansIII. Inhibition of Phagocytosis
Authors: Bulmer G. S. , Sans M. D.
Published: January 2020

Isolated nonhydrolyzed cryptococcal polysaccharide is a rather specific potent inhibitor of the phagocytosis ofCryptococcus neoformansby human leukocytes in vitro. When an encapsulated strain ofC. neoformanswas cultured in the nonencapsulated state, the rate of phagocytosis was three times greater than when the encapsulated form was used. Our theory that capsular material plays a role in the pathogenesis of cryptococcosis requires (i) thatC. neoformansexist in soil in a nonencapsulated state and (ii) that human phagocytes be capable of killing the organisms.
Study of the
Moraxella
Group I. Genus
Moraxella
and the
Neisseria catarrhalis
Group
Authors: Baumann P. , Doudoroff M. , Stanier R. Y.
Published: January 2020

A number of strains of oxidase-positive moraxellas and of neisserias related to
Neisseria catarrhalis
were characterized with respect to a number of nutritional and physiological properties and could be assigned to several species or species groups on the basis of their phenotypic traits. This grouping was consistent with that established by Bövre on the basis of transformation frequencies for streptomycin resistance. It is proposed to reserve the generic name
Moraxella
for the oxidase-positive rodshaped organisms, and a redescription of the genus is offered. Following the recent taxonomic proposals of Bövre and Henriksen, the specific name
Moraxella osloensis
is applied to the nutritionally unexacting strains that accumulate poly-β-hydroxybutyrate as carbon reserve. The nutritionally exacting strains are assigned to three distinct groups which can be regarded as separate species or as varieties of
M. lacunata
. The epithets applicable to these groups appear to be
lacunata, nonliquefaciens
, and
bovis
. The “false neisserias” could be assigned to at least three subgroups, one of which constitutes the clearly defined entity,
N. catarrhalis
, which could be distinguished from
N. caviae
and
N. ovis
.
Comparative Effect of Temperature on the Oxidative Metabolism of Whole and Disrupted Cells of a Psychrophilic and a Mesophilic Species of
Bacillus
Authors: Stokes J. L. , Larkin J. M.
Published: January 2020

We investigated the influence of temperature, in the range of 45 to 5 C, on the rate of oxidation of glucose and citrate by intact cells and cell-free extracts of psychrophilic
Bacillus psychrophilus
and mesophilic
B. thuringiensis
. Both glucose and endogenous oxidation by whole and disrupted cells of the psychrophile decreased more slowly with decrease in temperature than did glucose and endogenous oxidation by whole and disrupted cells of the mesophile. Similar results were obtained for the oxidation of citrate by cell-free extracts. Since substrate permeability is not involved in the oxidative metabolism of the cell-free extracts, we concluded that the internal enzymes of the psychrophile differ from those of the mesophile.
Induced Sensitization of Normal Laboratory Animals toBrucella abortusEndotoxin
Authors: Freedman Henry H. , Fox Alfred E. , Willis R. Suzanne , Schwartz Benjamin S.
Published: January 2020

A Boivin preparation ofBrucella abortus, unlike common enterobacterial endotoxins, failed to depress water intake or increase numbers of hemolysin-producing spleen cells in mice, or to cause delayed inflammatory reactions in rabbit skin. Reactivity to theB. abortusendotoxin was found only in animals which were previously given the endotoxin with, but not necessarily in, complete Freund's adjuvant. Previous treatment with the endotoxin in saline or with only the adjuvant was ineffective. Sensitization appeared within 10 days and waned after 5 weeks. Passive sensitization was obtained with sensitized donor spleen cells but not with serum. Serum antibody titers did not correlate with the appearance and disappearance of sensitization.
Resolution and Identification of Ribosomes from Mycobacteria
Authors: Trnka L. , Wiegeshaus E. , Smith D. W.
Published: January 2020

Ribosomes were isolated from mycobacteria (BCG) by differential centrifugation by use of a modification of Nirenberg's procedure. Individual components of the ribosomal spectrum were resolved in linear sucrose density gradients. Sedimentation constants of the individual components were determined by analytical ultracentrifugation. Ribosomes from
escherichia coli
labeled with
14
C-uracil were used as markers for an independent confirmation of the identity of individual peaks. The typical ribosomal spectrum of 70
S
units and 50
S
and 30
S
subunits was obtained in tris(hydroxymethyl)aminomethane buffer with 0.01
m
Mg(CH
3
COO)
2
. This corresponds to the ribosomal spectrum obtained in
E. coli
under comparable conditions. In 0.0001
m
Mg
2+
, the 70
S
units were dissociated to 50
S
and 30
S
particles. Pancreatic ribonuclease produced no significant changes in main ribosomal components. The isolation techniques used in this work precluded the recognition of polyribosomes.
N
-Methyl Groups in Bacterial Lipids III. Phospholipids of Hyphomicrobia
Authors: Goldfine Howard , Hagen Per-Otto
Published: January 2020

The phospholipids of
Hyphomicrobium vulgare
NQ-521 have been separated by preparative thin-layer chromatography and analyzed by paper chromotography of the water-soluble products of acid and mild alkaline hydrolysis. The principal phospholipids are phosphatidyl ethanolamine (23%), phosphatidyl
N,N
′-dimethylethanolamine (36%), lecithin (29%), and phosphatidyl glycerol (10%). Three other strains of
Hyphomicrobium
were found to have similar phospholipid compositions. Growing cells incorporated the methyl group of methionine into lipid-bound
N,N
′-dimethylethanolamine and choline. Experiments with sonic extracts of
H. vulgare
NQ-521 and
14
C (methyl)
S
-adenosylmethionine demonstrated the formation of phosphatidyl
N
-monomethylethanolamine in addition to the dimethylethanolamine and choline phosphatides.
Agar Medium for the Selective Enumeration of Coagulase-positive
Staphylococcus
from the Rat Alimentary Tract
Authors: Dickinson Anne B. , Raibaud P. , Mocquot G.
Published: January 2020

A selective agar medium (medium J
1
) is proposed for the quantitative enumeration of egg yolk-positive (EYP) and egg yolk-negative (EYN)
Staphylococcus pyogenes
from the digestive tract and feces of the rat. This medium, buffered at
p
H 5.0, is composed of acid casein hydrolysate and yeast extract with 7.5% sodium chloride, 1.6% sodium pyruvate, 0.0008% 2,3,5-triphenyltetrazolium chloride (TTC), and 6% egg yolk emulsion. Inoculation is by the pour-plate method and incubation is at 38 C in a water-jacketed incubator for 36 hr. Colonies of
S. pyogenes
reduce TTC; EYP strains are surrounded by a halo of opacity; and EYN strains may be surrounded by a red halo, but no opacity. Small, white colonies of
S. epidermidis
may develop, but
Micrococcus
, and all other groups of
Staphylococcus
recognized in the rat intestinal flora, are inhibited. Other bacterial genera, notably
Bacillus, Corynebacterium, Proteus
, and
Streptococcus
, are also inhibited.
Polynucleotide Homologies of
Brucella
Deoxyribonucleic Acids
Authors: Hoyer Bill H. , McCullough Norman B.
Published: January 2020

Deoxyribonucleic acids (DNA's) extracted from organisms presently placed in the genus
Brucella
(
B. abortus, B. melitensis, B. neotomae
, and
B. suis
) possessed very similar polynucleotide sequences. Unlabeled, single-stranded DNA fragments from
B. abortus, B. melitensis, B. neotomae
, and
B. suis
were equally effective in competing with the interaction of corresponding radiolabeled, single-stranded DNA fragments with their homologous DNA-agars. Unlabeled fragments of
B. ovis
, however, did not compete as effectively as the homologous, unlabeled DNA's, and this organism, therefore, had a detectably different polynucleotide composition. The mole percentages of guanine plus cytosine in
Brucella
DNA's (56 to 58%) were also similar. DNA's from
Francisella tularensis, Escherichia coli
, and the slow loris did not compete.
Defective Guanine Uptake in an 8-Azaguanine-resistant Mutant of
Salmonella typhimurium
Authors: Thakar Jayendra H. , Kalle Gurudutt P.
Published: January 2020

An 8-azaguanine-resistant mutant,
azg-11
, derived from a guanine auxotroph,
gua-1
, of
Salmonella typhimurium
was isolated. This mutant was resistant to the analogue when grown on 2,6-diaminopurine, but showed greater susceptibility than the parent on guanine. Studies with the uptake of radioactive purines revealed that the mutant was defective in a mechanism for incorporation of guanine as well as of xanthine. Initial rates of uptake were determined for guanine at concentrations which were sufficiently low to make permeases limiting. The affinity constant
K
m
for the mutant was found to be 2.5 × 10
−4
m
; that of the parent was 2.3 × 10
−5
m
. Examination of cell-free extracts suggested that the purine nucleotide pyrophosphorylases, responsible for the conversion of free intracellular purines to the corresponding nucleotides, were present and unaltered. The results indicate that the mutant is defective in a mechanism for the active transport for guanine and possibly xanthine.
Biological Effects of Leptospiral Lipids
Authors: Stalheim O. H. V.
Published: January 2020

Lipids were extracted from virulent
Leptospira pomona
and were purified. These lipids fixed complement in the presence of antiserum to
L. pomona
but did not stimulate the production of homologous agglutinins in rabbits, mice, or hamsters. When subsequently challenged, all of the mice and hamsters were fully susceptible to
L. pomona
. The lipid material was neither dermonecrotic nor lethal for mice or hamsters, but 382 μg of lipid from virulent or avirulent leptospires inhibited the growth of normal mice. Leptospiral lipids were toxic for peritoneal macrophages maintained in vitro, and when administered simultaneously with a million lethal doses of
L. pomona
, the lipids hastened death of the hamsters, presumably by inhibiting phagocytosis early in the course of the infection.
Timing of Enzyme Synthesis During Outgrowth of Spores of
Bacillus cereus
I. Ordered Enzyme Synthesis
Authors: Steinberg William , Halvorson Harlyn O.
Published: January 2020

During outgrowth of spores of
Bacillus cereus
T, the pattern of enzymes synthesized varied with respect to time. The periods of synthesis of α-glucosidase,
l
-alanine dehydrogenase, and histidase were ordered; each began at a specific time and synthesis continued for only a brief period. An examination of the timing of induced α-glucosidase and induced histidase was made to determine whether specific regions of the genome were continually available for transcription and regulation during this period. Several observations indicated that inducers could function during outgrowth, but for only a limited time interval. The period of induced enzyme synthesis occurred over the same interval as that observed for uninduced and catabolically repressed cultures. When inducer was added partway through the period of gene expression, the level of enzyme induction was diminished. Addition of inducer at a time after the period of gene expression had no significant effect. Since messenger ribonucleic acid formed during outgrowth had a half-life of only a few minutes, it was concluded that ordered enzyme synthesis was a result of ordered transcription of the corresponding portion of the genome. An examination of the timing of induced α-glucosidase and histidase synthesized in the presence of actinomycin D supported this conclusion.
Identification of Malic Acid from Yeast
Authors: Bhattacharjee Jnanendra K. , Maragoudakis Michael E. , Strassman Murray
Published: January 2020

Evidence indicated an accumulation of
l
-malic acid in the synthetic growth medium of both lysine auxotrophs and wild-type yeast. Malic acid was isolated from growth experiments and was identified by paper and column chromatography, by comparison of infrared spectra with authentic
l
-malic acid, as well as enzymatically, as a substrate of malic dehydrogenase. Malic acid was accumulated when glucose was used as a carbon source. This did not occur when sodium lactate was the carbon source. Malic, succinic, and citric acids, and a few other as yet unidentified organic acids, were accumulated in the culture supernatant fluid when yeast was grown in a chemically defined medium. The accumulation of these acids had no obvious relation to the pathway for lysine biosynthesis.
Taxonomic Position in the GenusBrucellaof the Causative Agent of Canine Abortion
Authors: Jones Lois M. , Zanardi Marilyn , Leong Daniel , Wilson J. B.
Published: January 2020

The gram-negative organism causing abortion in dogs was examined in parallel with cultures representative of theBrucellaspecies and withBordetella bronchiseptica. The organism fits into the genusBrucellaand most closely resemblesB. suison the basis of its growth characteristics. It is of rough colonial morphology and is agglutinated by antisera prepared against roughBrucella. In mouse toxicity tests, no endotoxic activity could be demonstrated. In contrast to mostBrucellacultures, it does not utilize erythritol. Electron microscopy showed a cell wall structure similar to that of other gram-negative organisms. The question of whether the organism should be designatedBrucella canis, as proposed by Carmichael and Bruner, orBrucella suisbiotype 5 is discussed. The authors favor the designationBrucella canisbecause the organism lacks the lipopolysaccharide antigen associated with the smooth agglutinogen and endotoxin, and it does not utilize erythritol.
Fine-structural Correlates of Growth in Hyphae ofAscodesmis sphaerospora
Authors: Brenner Douglas M. , Carroll George C.
Published: January 2020

Mycelial mats ofAscodesmis sphaerosporawere fixed and embedded for electron microscopy, and thin sections of 1-mm blocks, taken from the 1st to the 7th mm behind the hyphal tips, were cut parallel to the long axis of the hyphae. The hyphal tip region is characterized by an outer zone of electron-transparent vesicles, 500 to 1,000 A in diameter, and is apparently associated with wall elaboration. Immediately behind this region, dense granules become evident along convoluted membrane systems and along the plasma membrane; in the same region are numerous small lomasomes in the lateral wall. As the hypha grows, septa are laid down at 3- to 7-min intervals at a distance of 200 to 250 μ behind the hyphal tip. A cylinder of endoplasmic reticulum is intimately involved in cross-wall deposition from its earliest stages; as the wall grows in, it becomes increasingly constricted in the pore region, finally assuming a torus-like configuration. Woronin bodies are shown to have a crystalline substructure and to originate in pouch-like membrane systems. Cross-walls from a 7- to 13-hr-old mycelium frequently show highly ordered structures in the vicinity of the pore. These structures may appear either as laminar stacks of discs to one side of the pore or as series of stubby concentric rings within the pore area itself. In the latter case, a mass of granular material is frequently seen plugging the pore. Other unusual organelles and inclusions in 7- to 13-hr hyphae are vesicles containing swirls of beaded or dilated membrane, membrane-enclosed rods, and stacks of unit membranes associated with spherical, electron-transparent vesicles.
Isolation, Composition, and Structure of Membrane of
Listeria monocytogenes
Authors: Ghosh B. K. , Carroll K. K.
Published: January 2020

The plasma membrane of
Listeria monocytogenes
strain 42 was prepared by osmotic lysis of protoplasts with tris(hydroxymethyl)aminomethane (Tris) buffer,
p
H 8.2, containing MgCl
2
and glucose, followed by washing with NaCl and MgCl
2
in Tris buffer. Electron microscopy showed that the preparation was not contaminated with cytoplasmic material. The membrane preparation was composed of 55 to 60% protein, 1.5% ribonucleic acid, 0.1% deoxyribonucleic acid, 1.3 to 2.3% carbohydrate, 0.17 to 0.38% amino sugar, 0.2 to 0.4% rhamnose, 3.5 to 4.0% phosphorus, 10.5 to 12.0% nitrogen, and 30 to 35% lipid. Amino acid composition of the washed membrane showed some variation from that of the whole cells. Sulfur-containing amino acids were not present in the membrane hydrolysate. The membrane carbohydrate contained glucose, galactose, ribose, and arabinose. The membrane lipid was 80 to 85% phospholipid and 15 to 20% neutral lipid. The lipid contained 2.3 to 3.0% phosphorus, 2.5 to 3.0% carbohydrate, and a very small amount of nitrogen (0.2 to 0.3%). The phospholipid was of the phosphatidyl glycerol type. Electron micrographs of the washed membrane showed three layers. The outer and inner layers varied in thickness from 25 to 37 A and the middle layer from 20 to 25 A. The total thickness varied between 85 and 100 A. These preparations contained many vesicles which stained heavily with lead citrate. Some vesicles were also attached to the protoplast ghosts in the form of extrusions or intrusions, or both. Membrane preparations obtained by lysis of protoplasts in the absence of MgCl
2
were fragmented and contained less lipid (20 to 22%) and ribonucleic acid (0.3 to 0.5%) than preparations prepared with MgCl
2
.
Metabolic Events Occurring During Recovery from Prolonged Glucose Starvation inEscherichia coli
Authors: Jacobson A. , Gillespie D.
Published: January 2020

The effects of starvingEscherichia colifor glucose and required amino acids were determined. The disappearance of the majority of the ribosomal population, particularly of the ribonucleic acid (RNA) moiety, was noted. The events during recovery are detailed, with emphasis placed on the timing, requirements, and control of deoxyribonucleic acid, RNA, and protein synthesis and on ribosome reassembly. Finally, the applicability of the system to the study of temperature-sensitive mutants is documented and discussed.
Acetate-nonutilizing Mutants of
Neurospora crassa
II. Biochemical Deficiencies and the Roles of Certain Enzymes
Authors: Flavell R. B. , Fincham J. R. S.
Published: January 2020

The levels of Krebs cycle, glyoxylate cycle, and certain other enzymes were measured in a wild-type strain and in seven groups of acetate-nonutilizing (
acu
) mutants of
Neurospora crassa
, both after growth on a medium containing sucrose and after a subsequent 6-hr incubation in a similar medium, containing acetate as the sole source of carbon. In the wild strain, incubation in acetate medium caused a rise in the levels of isocitrate lyase, malate synthase, phosphoenolpyruvate carboxykinase, acetyl-coenzyme A synthetase, nicotinamide adenine dinucleotide phosphate-linked isocitrate dehydrogenase, citrate synthase, and fumarate hydratase. Isocitrate lyase activity was absent in
acu-3
mutants;
acu-5
mutants lacked acetyl-coenzyme A synthetase activity; and no oxoglutarate dehydrogenase activity (or only low levels) could be detected in
acu-2
and
acu-7
mutants. In
acu-6
mutants, phosphoenolpyruvate carboxykinase activity was either very low or absent. No specific biochemical deficiencies could be attributed to the
acu-1
and
acu-4
mutations. The role of several of these enzymes during growth on acetate is discussed.
Mutants of
Escherichia coli
Defective in Ribonucleoside and Deoxyribonucleoside Catabolism
Authors: Karlström O.
Published: January 2020

From
Escherichia coli
B, mutants were prepared that lacked the enzymes adenosine deaminase, cytidine deaminase, and purine nucleoside phosphorylase. In each case, the mutant lacked enzyme activity for both ribonucleoside and deoxyribonucleoside. Mutants lacking purine nucleoside phosphorylase lost the capacity to cleave the nucleosides of adenine, guanine, and hypoxanthine.
Effective Elimination of Drug Resistance and Sex Factors in
Escherichia coli
by Sodium Dodecyl Sulfate
Authors: Tomoeda Munemitsu , Inuzuka Manabu , Kubo Noriko , Nakamura Sachiko
Published: January 2020

A method for effective elimination of drug resistance (R) and sex (F) factors in
Escherichia coli
K-12 strains by treatment with sodium dodecyl sulfate (SDS) is presented. Growth of
E. coli
harboring R or F factors in Penassay Broth containing SDS led to the loss of all or part of these genetic elements. Appearance of drug-susceptible or F
−
cells among survivors was observed after the culture reached the stationary phase. Drug-susceptible cells which had lost all of their resistance markers by SDS treatment could be efficiently infected with R or F factors. Among isolated segregants which came from resistant cells, tetracycline-susceptible cells were the major segregant class. Drug-susceptible cells gave no revertants to drug resistance. By treatment of F
+
cells with SDS, unusual F
+
cells which retained mating ability but showed resistance to M12 phage were also isolated, together with mutants of another type which lost mating ability but retained sensitivity to M12 phage. Since SDS is more toxic to R
+
cells than R
−
cells, the isolation of drug-susceptible or F
−
cells under these conditions may be partly attributable to selective growth of drug-susceptible or F
−
cells in SDS-Penassay Broth.
Hydrogen-oxidizing Methane Bacteria II. Electron Microscopy
Authors: Langenberg K. F. , Bryant M. P. , Wolfe R. S.
Published: January 2020

Comparison of the fine structure of the methanogenic organism from the culture known as
Methanobacillus omelianskii
with that of
Methanobacterium formicicum
revealed a great similarity. Both organisms exhibited a large number of intracytoplasmic membranous elements when stained with phosphotungstic acid. In contrast, no such elements were observed in
Methanobacterium ruminantium
.
Interaction of
Bdellovibrio bacteriovorus
and Host Bacteria I. Kinetic Studies of Attachment and Invasion of
Escherichia coli
B by
Bdellovibrio bacteriovorus
Authors: Varon Mazal , Shilo M.
Published: January 2020

Quantitative methods were developed for the study of the early stages in the interaction of
Bdellovibrio bacteriovorus
and host bacteria. Attachment measurements were based on the differential filtration of host and parasite. Invasion was measured by estimation of radioactively labeled
Bdellovibrio
cells remaining attached to the host cells after mechanical agitation. The kinetics of attachment and the final number of
Bdellovibrio
cells attached were dependent on the multiplicity of the parasite, the composition and
p
H of the medium, and the incubation temperature. Inhibitors of
Bdellovibrio
motility, including chelating agents, NaN
3
, and low
p
H, all inhibited attachment, as did anaerobiosis. Ultraviolet-killed host cells retained their competence for attachment of
Bdellovibrio
cells, whereas heat-killed cells lost it. Invasion was selectively inhibited by inhibitors of protein synthesis, such as streptomycin, puromycin, and chloramphenicol. These antibiotics had no effect on attachment.
Response and Specificity of Antibodies forCandida albicans
Authors: Fukazawa Yoshimura , Shinoda Takako , Tsuchiya Takeshi
Published: January 2020

Rabbit antibodies forCandida albicans, reacting in agglutination and fluorescent-antibody reactions, were present in both IgM and IgG protein fractions. The two types of immune globulins were separated from ammonium sulfate-precipitated γ-globulin either by filtration through a column of Sephadex G-200 or by diethylaminoethyl column chromatography performed by stepwise elution with various concentrations of sodium chloride. In the fluorescent-antibody test, initial separation of the IgG fraction, prior to its conjugation with dye, proved to be essential for the high specificity of this reaction. Investigation of the specificities of the two types of antibodies revealed that the IgG was highly specific, whereas the IgM was not very specific. Each antigen fraction, extracted by various methods, demonstrated its own characteristic antibody response. Only the IgG fraction yielded serotype-specific antibody useful for detection of a serotype ofC. albicansin agglutination and fluorescent-antibody tests. The results indicate the importance of IgG for specific serological reactions with theCandidaspecies.
Effect of Tryptophan and Selected Analogues on Body Temperature of Endotoxin-poisoned Mice
Authors: Moon Robert J. , Berry L. Joe
Published: January 2020

The effect of endotoxin on the body temperature of mice was studied in animals housed without bedding at an environmental temperature of 15 C. Rectal temperatures were measured during the initial 3 to 5 hr of exposure. Doses of endotoxin ranging from 0.01 to 1
ld
50
, as determined for mice maintained at 25 C, produce a hypothermia in proportion to dose. Concurrent injection of tryptophan magnified this response in a dose-dependent manner. Cyproheptadine, an antiserotonin drug, antagonized both the hypothermia produced by serotonin alone, and the augmentation of hypothermia produced by tryptophan in endotoxin-poisoned mice. α-Methyltryptophan, an analogue of the amino acid that is known to induce tryptophan pyrrolase, also antagonized the increased hypothermia produced by tryptophan. These data support a previous suggestion that inhibition of tryptophan pyrrolase in endotoxin-poisoned mice has the effect of funneling injected tryptophan into the serotonin pathway.
Growth and Bacteriolytic Activity of a Soil Amoeba,
Hartmannella glebae
Authors: Upadhyay J. M.
Published: January 2020

A soil amoeba,
Hartmannella glebae
, could grow on a variety of gram-positive and gram-negative bacteria, although the rate of growth was faster in the presence of gram-negative bacteria. The amoeba, however, could not use yeasts, molds, or a green alga as a nutritional source. The extract prepared from amoebae grown in the presence of
Aerobacter aerogenes
and
Alcaligenes faecalis
could lyse intact cells and cell walls of many gram-positive bacteria at different rates. The spectrum of lytic activity was similar to that of egg-white lysozyme, with the exception that several species and strains of
Bacillus, Micrococcus
, and
Staphylococcus
were resistant to lysozyme and susceptible to the extract. The gram-negative bacteria tested were resistant.
Salt-induced Contraction of Bacterial Cell Walls
Authors: Marquis Robert E.
Published: January 2020

Intact
Bacillus megaterium
cells were found to contract as much as 26% in terms of dextran-impermeable volume when transferred from water to unbuffered, non-plasmolyzing NaCl solutions. This shrinkage appeared to be primarily due to electrostatic wall contraction rather than to any osmotic response of the cells. A variety of salts (but not sucrose) added to water suspensions of isolated cell walls caused protons to be released from the walls with resultant lowering of suspension
p
H and contraction of the structures. In effect,
B. megaterium
walls behaved as flexible, amphoteric polyelectrolytes, and their compactness in aqueous suspensions was affected by changes in environmental ionic strength and
p
H. Isolated walls were most compact in low ionic strength media with a
p
H of about 4, a value close to the apparent isoelectric
p
H of wall peptidoglycan. Electrostatic attractions appeared to play a major role in determining the compactness of highly contracted walls, and the walls responded to increased environmental ionic strength by expanding. In contrast, electrostatic repulsions were dominant in highly expanded walls, and increased environmental ionic strength induced wall contraction. Walls of whole bacteria also shrank when the cells were plasmolyzed. This second type of contraction seemed to result from relief of wall tension during plasmolysis, and it could be induced with nonionic solutes. Thus, cell wall tone in
B. megaterium
appeared to be set both by mechanical tension and by electrostatic interactions among wall ions.
Measurement of Steady-State Growth Rates of a Thermophilic Alga Directly in Nature
Authors: Brock Thomas D. , Brock M. Louise
Published: January 2020

Steady-state growth rates of thermophilic algae can be determined directly in nature in the flowing waters of a hot spring channel by measuring the rate of loss of algal cells when the channel is darkened. The half time of the loss rate in the steady state is identical to the generation time. We studied the unicellular blue-green alga
Synechococcus
in Yellowstone National Park. Temperature and flow rate remained relatively constant throughout the experiment. Quantitative cores were taken and homogenized; the algal cells were then counted by use of a Petroff-Hausser counting chamber. After ascertaining that the algal population was in a steady state, the channel was darkened in such a way that neither flow rate nor temperature was altered. The population began to decrease within 1 day; the loss rate was exponential with time for 2 to 3 decades. Half times were then calculated from these loss rates. The growth rates found were considerably lower than those for the same organism in laboratory culture. The results suggest that in nature the organism may be an obligate phototroph. In two cases, after the algal populations decreased to an undetectable level, the dark covers were removed and the rate of recolonization was measured. The kinetics of recolonization were different from the kinetics of washout.
Competence and Deoxyribonucleic Acid Uptake in
Bacillus subtilis
Authors: Singh R. N. , Pitale M. P.
Published: January 2020

The distribution of uninucleate and multinucleate cells of
Bacillus subtilis
, fractionated by zonal centrifugation, shows that the uninucleate cells are most likely to be competent. Only the competent fraction of the population incorporates deoxyribonucleic acid.
Fractionation of Transformable Bacteria from Competent Cultures of
Bacillus subtilis
on Renografin Gradients
Authors: Cahn Florence Haseltine , Fox Maurice S.
Published: January 2020

A population of
Bacillus subtilis
can be fractionated into at least two components on the basis of their buoyant densities on a Renografin gradient. In competent cultures, most, and perhaps all, of the competent bacteria appear in the lighter fraction which composes 2 to 10% of the bulk population. These “lighter” bacteria are the only bacteria capable of incorporating transforming deoxyribonucleic acid.
Purification of Competent Cells in the
Bacillus subtilis
Transformation System
Authors: Hadden Charles , Nester E. W.
Published: January 2020

Transformed cells have been separated from nontransformed cells by centrifugation on a density gradient of Renografin-76. Separation was achieved both on a linear gradient and on a discontinuous gradient. Under optimal conditions, all of the cells in one band (median density, 1.110 g/ml) were transformants, whereas virtually all cells in the other (median density, 1.131) were nontransformants. In some instances, recentrifugation of the transformant band further enriched the transformant population. The transformed population can also be enriched by zonal centrifugation in a linear gradient of Ficoll. However, this technique is far less efficient than centrifugation in Renografin-76. Since the density of competent cells is identical to that of transformants, we conclude that the low density is a property of competent cells. The significance of this low density to the physiology of competent cells is discussed.
Drug Resistance of Staphylococci VI. Genetic Determinant for Chloramphenicol Resistance
Authors: Kono Megumi , Ogawa Kiyoko , Mitsuhashi Susumu
Published: January 2020

Naturally occurring strains of staphylococci which are resistant to chloramphenicol (CM) inactivate this antibiotic. One of the inactivation products of CM showed the chromatographic behavior of 3-acetoxychloramphenicol. Induction of resistance occurred after prior exposure to subinhibitory concentrations of the antibiotic. The resistance of induced populations, as well as CM-inactivation ability, was decreased when they were grown in CM-free medium. The CM-inactivation property was transduced together with CM resistance. Transductional analysis and CM-resistance elimination experiments indicated that CM resistance in naturally occurring strains of staphylococci is mainly accounted for by inactivation of the drug.
Purification and Properties of In Vitro–produced Anthrax Toxin Components
Authors: Fish Donald C. , Mahlandt Bill G. , Dobbs James P. , Lincoln Ralph E.
Published: January 2020

The three components of the toxin of
Bacillus anthracis
, edema factor (EF), protective antigen (PA), and lethal factor (LF), were purified 197-, 156-, and 1,025- fold, with 38, 78, and 11% recovery, respectively. Each purified component was serologically active, distinct, and free from the other components. The purified EF produced edema when mixed with PA, and the purified PA was an active immunogen. The components did not appear to be simple proteins by spectrophotometric analysis. As they were purified, the
p
H range in which they were most stable narrowed, centering between
p
H 7.4 and 7.8. Heat readily destroyed the biological activity of the components but not their serological activity. The rat lethality test showed that, with a constant amount of LF and an increasing amount of PA, the time to death reached a minimum and then was extended. When an increasing amount of LF was added to a constant amount of PA, the time to death became shorter as more LF was added. The biological, immunological, and serological properties of the components were shown to vary independently with storage and extent of purification so that serological activity was not always directly correlated with biological activity. Evidence is presented that the components can exist in different molecular configurations or as aggregates, and that this property is influenced by the state of component purity and by the environment.
Virulent and Avirulent Encapsulated Variants ofStaphylococcus aureus
Authors: Wiley Bill B. , Maverakis Nick H.
Published: January 2020

There are at least two serologically distinct capsular types of coagulase-positiveStaphylococcus aureus. Until now, unequivocal evidence for encapsulation of the Smith diffuse variant was lacking. However, the data presented in this paper provide definitive details of encapsulation of the Smith strain. A marked difference inld50values for the two serologically distinct capsular types ofS. aureuswas demonstrated. The paradoxical behavior of these two strains suggested that the host was resistant to one and was susceptible to the other. A survey of the carriage incidence in mice for staphylococci and staphylococcal capsular antibodies disclosed the presence of staphylococci and capsular antibodies in these animals. The capsular antibodies detected were reactive against only one of the capsular types ofS. aureus. None of the sera from the mice surveyed possessed capsular antibodies against the Smith diffuse variant, but the average incidence for the capsular antibodies against the wound mucoid type was 46%. We postulated that the susceptibility of the mice to the Smith diffuse variant was caused by the absence of protective, type-specific capsular antibodies. Conversely, the resistance of the mice to the wound mucoid staphylococci may have been a result of the presence of type-specific capsular antibodies.
Localization and Regulation of Synthesis of Nitrate Reductase in
Escherichia coli
Authors: Showe Michael K. , DeMoss J. A.
Published: January 2020

The nitrate reductase of
Escherichia coli
K-12 was localized in a particulate fraction of the cell and it sedimented as if it were bound to a large substructure that is subject to fragmentation during cell disruption procedures. Soluble enzyme, exhibiting a homogenous profile in sucrose gradients, was released from this fraction by an alkaline-heat treatment. Less than 1.5% of total active nitrate reductase apparently occurred in this soluble form during the course of formation of the particulate enzyme. Enzyme synthesis was repressed by aeration in the presence or absence of nitrate. Under anaerobic conditions, nitrate reductase was synthesized at a rate that could be increased 20-fold by the addition of nitrate. When enzyme synthesis was initiated by induction with nitrate or anaerobiosis, biphasic kinetics were obtained. We interpreted the results as evidence for the existence of a redox-sensitive repressor which mediates nitrate reductase regulation.
Acid Protease Synthesis by
Mucor pusillus
in Chemically Defined Media
Authors: Somkuti G. A. , Babel F. J.
Published: January 2020

The acid protease synthetized by
Mucor pusillus
in chemically defined medium displayed a gel filtration pattern and optimal
p
H similar to that shown by protease isolated from complex medium. Protease synthesis was influenced by the concentration of sulfur in the medium. At sulfur concentrations greater than 10
−4
m
, protease synthesis was suppressed, indicating a controlling role of sulfur compounds in the synthesis of extracellular protein. Inorganic phosphate was found to be without negative effect on enzyme synthesis. Growth studies showed that
M. pusillus
had the capacity to utilize ammonium N, nitrate N, amino N, and urea.
Nutritional Factors Influencing the Development of Competence in the
Bacillus subtilis
Transformation System
Authors: Wilson Gary A. , Bott Kenneth F.
Published: January 2020

Cultures of
Bacillus subtilis
developed competence for the uptake of deoxyribonucleic acid in a chemically defined medium with a predictable, reproducible pattern. The gross effects of individual amino acids were determined. Seven amino acids, most of which are reported to be major components of the cell wall, were shown to impair the development of maximal levels of competence. When the synthetic growth medium was supplemented with a mixture of the nine amino acids which we found to stimulate the development of competence, the level of transfection was increased to 10 to 15% of the population. The actual level of competence in these populations was assayed by transformation of unlinked bacterial markers and by two different transfection assays. The results indicate that calculations from cotransfer of unlinked markers overestimates the degree of competence in highly competent populations of
B. subtilis
, whereas the number of plaques obtained in transfection is an under-estimate of the actual level of competence. The results are interpreted to indicate that neither method of analysis gives a true estimate of the competent population, but that more than 80% of the cells may be competent.