bluuebunny/crossref_metadata_2025 huggingface dataset:
Production of Nitric Oxide and Nitrous Oxide During Denitrification by
Corynebacterium nephridii
Authors: Renner E. D. , Becker George E.
Published: January 2020

Resting cells of
Corynebacterium nephridii
reduce nitrate, nitrite, and nitric oxide to nitrous oxide under anaerobic conditions. Nitrous oxide production from nitrite was optimal from
p
H 7.0 to 7.4. The stoichiometry of nitrous oxide production from nitrite was 99% of the theoretical—two moles of nitrite was used for each mole of nitrous oxide detected. Hydroxylamine increases gas evolution from nitrite but inhibits the reduction of nitric oxide to nitrous oxide. Hydroxylamine is converted to nitrogenous gas(es) by resting cells only in the presence of nitrite. Under certain conditions nitric oxide, as well as nitrous oxide, was detected.
Nature of the Ethylenediaminetetraacetic acid Requirement for Transformation of
Bacillus subtilis
with Single-Stranded Deoxyribonucleic Acid
Authors: Tevethia M. J. , Mandel M.
Published: January 2020

The ethylenediaminetetraacetate (EDTA) requirement for transformation of
Bacillus subtilis
with single-stranded deoxyribonucleic acid (DNA) was examined. The results indicate that a chelating agent such as EDTA is a stringent requirement for transformation with single DNA strands only at nonsaturating DNA concentrations, and that EDTA, when required, must be present during several steps in the transformation process and appears to insure the survival of single-stranded DNA by rendering a nuclease in competent populations inactive.
Fertility Regulation in F-Like Resistance Transfer Factors
Authors: Hoar David I.
Published: January 2020

Mutants of the R factor R100 have been isolated that mediate high-frequency transfer of the R factor during conjugation. Complementation tests revealed two classes of mutants, operator-constitutive and repressor-negative. Some of the latter class were suppressible by amber and ochre suppressors. The results support a simple model of regulation for the control of R-factor-mediated piliation.
Biochemical Changes During Fungal Sporulation and Spore Germination
Authors: Leighton T. J. , Stock J. J.
Published: January 2020

Macroconidia of
Microsporum gypseum
release free amino acids into the medium during germination. A single alkaline protease is also found in the germination supernatant fraction. The purified protease is capable of hydrolyzing isolated spore coats in vitro. Phenyl methyl sulfonyl fluoride (PMSF) is an effective inhibitor of the protease. Incorporation of PMSF at 10
−4
m
into the germination system inhibits spore germination and the release of free amino nitrogen. Addition of PMSF after germ tube emergence is completed has no effect on subsequent outgrowth. The addition of exogenous purified protease to quiescent spores results in more than a 2.5-fold increase in germinated spores. It is concluded that spore coat proteolysis is an essential event in the germination of dermatophyte macroconidia. A model system to explain macroconidial germination response to inhibition, temperature shift, and addition of protease is presented.
Facultatively Parasitic Strain of
Bdellovibrio bacteriovorus
Authors: Diedrich D. L. , Denny C. F. , Hashimoto T. , Conti S. F.
Published: January 2020

A strain of
Bdellovibrio bacteriovorus
(designated strain UKi2) was isolated which was capable of growing either saprophytically in host-free medium or endoparasitically in
Escherichia coli
B/r. It was quantitatively determined that each bdellovibrio could develop in solid medium to produce a colony, and 65% of the cells in a late exponential-phase culture were capable of inducing
E. coli
B/r spheroplasts. A photomicrographic sequence of single
E. coli
spheroplasts containing bdellovibrios demonstrated that parasitically derived
B. bacteriovorus
UKi2 could develop saprophytically after release from the host cells. Strain UKi2 appears to be morphologically quite similar to previously described obligately parasitic bdellovibrios; biochemical data on this strain suggests its close relationship to some of the previously described host-independent strains of
Bdellovibrio
.
Endonuclease from
Micrococcus luteus
Which Has Activity Toward Ultraviolet-Irradiated Deoxyribonucleic Acid: Its Action on Transforming Deoxyribonucleic Acid
Authors: Setlow R. B. , Setlow Jane K. , Carrier W. L.
Published: January 2020

An endonuclease purified from
Micrococcus luteus
makes single-strand breaks in ultraviolet (UV)-irradiated, native deoxyribonucleic acid (DNA). The purified endonuclease is able to reactivate UV-inactivated transforming DNA of
Haemophilus influenzae
, especially when the DNA is assayed on a UV-sensitive mutant of
H. influenzae
. After extensive endonuclease action, there is a loss of transforming DNA when assayed on both UV-sensitive and -resistant cells. The endonuclease does not affect unirradiated DNA. The results indicate that the endonuclease function is involved in the repair of biological damage resulting from UV irradiation and that the UV-sensitive mutant is deficient in this step. We interpret the data as indicating that the various steps in the repair of DNA must be well coordinated if repair is to be effective.
Outer Layers of the
Azotobacter vinelandii
Cyst
Authors: Pope Leodocia M. , Wyss Orville
Published: January 2020

Ruthenium red stained a capsule external to the exine of the
Azotobacter
cyst. The central body is therefore surrounded by three layers, the intine, the exine, and the capsule, all containing acid mucopolysaccharide. Vesicles that appear to originate from the contracting cell membrane of the central body may account for the lipid content of the intine. The exine is composed of laminated sheets that tend to fragment into hexagonal pieces.
Chromatography of Microbial Lipids by Centrifugation Through Microparticulate Gel
Authors: Ribi Edgar , Filz Charles , Ribi Karin , Goode Granville , Brown William , Niwa Makoto , Smith Robert
Published: January 2020

An improved apparatus and a procedure are described by which the migration of sample components in column chromatography is accelerated by centrifugal force, thereby making it possible to use beds of densely packed gel prepared with ultrafine silica. This technique was used to resolve components of certain lipid mixtures where other methods have failed, and it has been found generally useful as an adjunct to other methods for the fractionation of lipids. Biologically active phosphoglycolipids from
Mycobacterium tuberculosis
and a phosphatidylglycerol-like substance from
Mycoplasma pneumoniae
which formed single spots on thin-layer chromatographic plates were each found to contain a major and several minor components by centrifugal chromatography. The method enabled us to isolate individual components of Wax D from
M. tuberculosis
rather than a spectrum of components. Minor components were resolved which, although present in insufficient quantity to influence results of chemical analyses, may be responsible for biological activity. The apparatus provides an essentially closed system which reduces highly volatile solvents to minimal evaporation during the chromatographic process. Samples are applied in solution and are not allowed to dry on the columns until after separation has been achieved. Consequently, polar, labile microbial lipids can be resolved without the use of harsh reagents which destroy some of their properties. Single components may be harvested by cutting and removing appropriate segments of the larger chromatograms or by eluting them from the columns.
Possible Involvement of β-Lactamase in Sporulation in
Bacillus cereus
Authors: Ozer Joy Hochstadt , Saz Arthur K.
Published: January 2020

Nonreverting β-lactamase-negative strains were isolated from the β-lactamase-constitutive strain,
Bacillus cereus
569 H. These strains differed from both β-lactamase-inducible and -constitutive strains not only in failure to produce β-lactamase but also in failure to autolyze on aging, delayed sporulation, and failure to release free spores from sporangia when produced. The addition of
B. cereus
β-lactamase of 15% purity to a final concentration of 10 IU/ml stimulates sporulation and particularly the release of free spores in culture from sporangia of strain 569 (inducible wild-type), 569/H (constitutive mutant of 569), and HPen
−
, a nonreverting β-lactamase strain isolated from 569/H in this laboratory. Cultures of HPen
−
did not release free spores without this treatment. Similar stimulation of sporulation and spore release by β-lactamase from
B. cereus
were observed in another β-lactamase-negative strain derived from 569/H as well as in certain sporogeny mutants of
B. subtilis
. The β-lactamase preparation used in these experiments was free of peptidases, proteases, and autolysins capable of solubilizing wall from vegetative cells. These results, taken with our previous finding that a soluble peptidoglycan inducer becomes available in cultures of
B. cereus
only at sporulation and that normal derepression of β-lactamase accompanies normal sporulation, suggest that β-lactamase in
B. cereus
may be involved in peptidoglycan metabolism during sporulation and possibly the breakdown of sporangial wall with the concomitant release of mature spores.
Cholesterol Requirement of Mycoplasmas
Authors: Razin Shmuel , Tully Joseph G.
Published: January 2020

Cholesterol requirement for growth of mycoplasmas was tested in a serum-free medium supplemented with albumin,l-arginine, palmitic acid, and various concentrations of cholesterol dissolved in Tween 80. In cases in which Tween 80 was shown to inhibit growth, the test medium was supplemented with cholesterol dissolved in ethanol. Of the 31 species examined, all butMycoplasma laidlawii, M. granularum, andMycoplasmaspecies strain S-743 exhibited a growth response to cholesterol. No requirement for cholesterol could be shown with the stable L-phase variants ofStreptobacillus moniliformisandProteusspecies. The results provide experimental support for the view that the large majority of the establishedMycoplasmaspecies require cholesterol for growth.
Comparative Immunological Studies of TwoPseudomonasEnzymes
Authors: Stanier R. Y. , Wachter D. , Gasser Charlotte , Wilson A. C.
Published: January 2020

Crystalline preparations of muconate lactonizing enzyme and muconolactone isomerase, two inducible enzymes that catalyze successive steps in the catechol branch of the β-ketoadipate pathway, were used to prepare antisera. Both enzymes were isolated from a strain ofPseudomonas putidabiotype A. The antisera did not cross-react with enzymes of the same bacterial strain that catalyze the chemically analogous steps in the protocatechuate branch of the β-ketoadipate pathway, carboxymuconate lactonizing enzyme and carboxymuconolactone decarboxylase. The antisera gave heterologous cross-reactions of varying intensities with the muconate lactonizing enzymes and muconolactone isomerases ofP. putidabiotype B,P. aeruginosa, P. stutzeri, and all biotypes ofP. fluorescens, but did not cross-react with the isofunctional enzymes ofP. acidovorans, ofP. multivorans, and of two bacterial species that belong to other genera. The evolutionary and taxonomic implications of the findings are discussed.
Heterogeneity of Phospholipid Composition in the Bacterial Membrane
Authors: Tucker Anne N. , White David C.
Published: January 2020

Heterogeneity in the distribution or binding of the membrane phospholipids was demonstrated in the membrane fragments released from
Haemophilus parainfluenzae
by treatment with ethylenediaminetetraacetic acid (EDTA)-tris(hydroxymethyl)-aminomethane (Tris). The membrane fragments released early in the EDTA-Tris treatment contained two- to fivefold higher proportions of cardiolipin and phosphatidylglycerol and less phosphatidylethanolamine as well as phospholipids with threefold lower specific activity of the phospholipid phosphate after a short pulse of
32
P than were found in the residue. Heterogeneity was best demonstrated with shorter EDTA-Tris treatments and shorter periods of growth with
32
P. EDTA-Tris treatment appeared to progressively strip phospholipids from the cells that were synthesized at progressively later times.
Isolation of Monosomics in Yeast
Authors: Bruenn J. , Mortimer R. K.
Published: January 2020

Tetraploid cultures of
Saccharomyces cerevisiae
triplex (A/A/A/a) at several loci were sporulated. All the diploid spores are expected to be homozygous (A/A) or heterozygous (A/a) and, hence, to have the dominant phenotype. Cells lacking one of the chromosomes (monosomics) may show the recessive phenotype (a/−). Therefore, spores that grew on complete medium but failed to grow on the relevant synthetic single-omission media were presumed to be monosomic. These isolates were further characterized by sporulation, and several stable monosomics were established.
Selection of
AraB
and
AraC
Mutants of
Escherichia coli
B/r by Resistance to Ribitol
Authors: Katz Leonard
Published: January 2020

The growth of strain
araC
c
67
, which produces the enzymes of the
ara
operon constitutively, is inhibited by the addition of ribitol. Isolation of strains resistant to ribitol yields mutants of either the
araB
or
araC
genes. A model to account for the inhibition by ribitol is discussed.
Yields of
Hydrogenomonas eutropha
from Growth on Succinate and Fumarate
Authors: Bongers Leonard
Published: January 2020

Molar growth yields were determined from chemostat cultures of
Hydrogenomonas eutropha
on succinate and on fumarate. The yields from culture on succinate were about 12 g higher than on fumarate. Assuming this difference to be equivalent to 1 molecule of adenosine triphosphate, it is concluded that the oxidation by oxygen of the
Hydrogenomonas cytochrome b
yields 1 molecule of adenosine triphosphate.
Synergism Between Cysteine and Alkylating Agents
Authors: Rosenkranz Herbert S. , Carr Howard S. , Zyroff Jack
Published: January 2020

Contrary to expectation,
l
-cysteine did not protect
Escherichia coli
from the lethal action of two monofunctional alkylating agents (nitrosomethylurethane and methylmethane sulfonate). The antibacterial action of these compounds was actually greatly enhanced by
l
-cysteine. This synergistic effect was also exhibited, to some extent, by
d
-cysteine but not by homocysteine,
S
-methylcysteine, or serine. The synergistic action between methylating agents and
l
-cysteine was not due to the formation of
S
-methylcysteine.
l
-Cysteine had no effect on the bacteriostatic action of ethylmethane sulfonate.
Biosynthesis of 4-Aminobenzoate in
Escherichia coli
Authors: Huang Minta , Gibson F.
Published: January 2020

Two different mutations (
pabA
and
pabB
) affecting 4-aminobenzoate biosynthesis were obtained in strains of
Escherichia coli
lacking chorismate mutase and anthranilate synthetase activity, thus allowing study of the pathway of biosynthesis of 4-aminobenzoate by use of cell extracts of strains carrying the
pab
mutations. Two components with approximate molecular weights of 9,000 (component A) and 48,000 (component B) are concerned in the biosynthesis of 4-aminobenzoate from chorismate by
E. coli
. No diffusible intermediate compound could be detected.
Effect of Miracil D on Marker Frequency Ratio and Cytotoxicity in
Bacillus subtilis
Authors: Haidle C. W. , Brinkley B. R. , Mandel Manley
Published: January 2020

When Miracil D was added to mid-log phase
Bacillus subtilis
cells, the rate of growth decreased immediately, and the turbidity of the culture began to decrease within 15 to 20 min after addition of the drug. At this stage, ghostlike cells were observed under phase-contrast microscopy. The viable count also began to decrease rapidly after 15 min in the presence of the drug, and within 60 min there was a 10,000-fold reduction in viability. Incorporation of
3
H-thymidine into deoxyribonucleic acid (DNA) proceeded normally up to 20 min of exposure to the drug, after which incorporation ceased. Cells which were prelabeled with
3
H-thymidine and exposed to the drug released labeled DNA into the medium after 15 to 20 min. Results of transformation analyses with donor DNA from cells grown in the presence of Miracil show a decrease with time in the ratio of origin markers to terminus markers. Electron micrographs of sectioned cells grown for 5, 10, and 15 min in the presence of Miracil D show profound cytotoxic effects. The most striking aspect of such cells is the very condensed appearance of the nucleoid. In those cells about to divide, the nucleoid appears not to be properly separating, being strung out in the region of the developing septum. Finally, the mesosome is very poorly defined or entirely absent in Miracil-treated cells.
Morphology and Ultrastructure of Normal Rod-Shaped and Filamentous Forms of
Erwinia amylovora
Authors: Huang Pi-Yu , Goodman Robert N.
Published: January 2020

Filamentous cells of
Erwinia amylovora
were usually 3 to 35 times longer than the normal rod-shaped ones, and only the former produced minicells.
Photoactivation of Urocanase in
Pseudomonas putida:
Possible Role in Photoregulation of Histidine Metabolism
Authors: Hug Daniel H. , Hunter John K.
Published: January 2020

Irradiation by near-ultraviolet light of cells or extracts of
Pseudomonas putida
increased the urocanase activity. Irradiated cells exhibited enhanced catabolic activity on histidine and urocanate.
Molecular Recombination Between R-Factor Deoxyribonucleic Acid Molecules in
Escherichia coli
Host Cells
Authors: Nisioka Taizo , Mitani Michiko , Clowes Royston C.
Published: January 2020

Three previously studied R factors were used: 222/R4, controlling transmissible resistance to sulfonamide, streptomycin, chloromycetin, and tetracycline (SU
r
SM
r
CM
r
TC
r
); 222/R3, a derivative of 222/R4 (now termed 222/R3W) having lost TC
r
; and R15, controlling infectious resistance to SU and SM only. Two types of derivative R factors were isolated from 222/R4 by serial subculture in
Salmonella
species. One derivative, termed 222/R1, lost resistance to SU, SM, and CM, and the other, termed 222/R3N, lost only TC
r
. Each factor was transferred to a standard
Escherichia coli
K-12 host. Recombinant factors of 222/R4 phenotype were isolated by selection after mixed culture of
E. coli
(222/R1)
+
and (222/R3N)
+
strains. Density-gradient equilibrium centrifugation of lysates of
E. coli
R
+
hosts in the presence of ethidium bromide separated R-factor deoxyribonucleic acid (DNA) as a heavy satellite peak which was subjected to electron microscopy or analytical density gradient centrifugation. Each DNA comprised a unimolecular species of circular DNA. The contour of R15 measured 22.3 μm [equivalent to 46 × 10
6
atomic mass units (AMU)], and that of 222/R4 measured 33.6 μm (70 × 10
6
AMU). 222/R3W appeared to be a point mutant or small deletion of 222/R4 with an almost identical size, whereas 222/R3N had lost a DNA segment of about 3 μm, and measured 30.3 μm or 63 × 10
6
AMU. The 222/R1 factors also appeared to have arisen by loss of DNA from 222/R4, 222/R1A being 22.3 μm or 46 × 10
6
AMU, whereas all other 222/R1 factors appeared to be duplicates, measuring 25.6 μm or 53 × 10
6
AMU. The DNA from six recombinant factors of R4 phenotype was indistinguishable in size and configuration from the parental 222/R4. In most cases, the number of R-factor copies (present as covalently closed circular molecules) per copy of the
E. coli
chromosome was less than 2, ranging from 1.2 to 3.3.
Cholesterol Inhibition of Isopentenyl Pyrophosphate Δ
3
,Δ
2
-Isomerase in
Mycoplasma laidlawii
Authors: Smith Paul F. , Smith Marie R.
Published: January 2020

Cholesterol inhibits isopentenyl Δ
3
,Δ
2
-isomerase of
Mycoplasma laidlawii
in an apparently competitive fashion. The conversion of mevalonic acid to isopentenyl pyrophosphate is slightly stimulated. Organisms grown in the presence of mevalonic-
2
-
14
C
acid contain small amounts of radio-label in nucleic acid and protein fractions. Most of the label is found in the lipids and is reduced dramatically in organisms grown with cholesterol. No significant accumulation of phosphorylated intermediates of polyterpene biosynthesis was observed in cells or culture supernatant fluid. All of the radioactivity appearing in the nucleic acid fraction occurs in the minor nucleoside, isopentenyl adenosine, of the transfer ribonucleic acid. The necessity for synthesis by the organisms of this minor nucleoside from mevalonic acid may explain the site of enzyme inhibition by cholesterol of polyterpene biosynthesis.
Effect of Potassium Chloride on the Uptake and Storage of Phosphate by
Saccharomyces mellis
Authors: Weimberg Ralph
Published: January 2020

The inorganic and polyphosphate pools of
Saccharomyces mellis
, grown in a medium containing excess phosphate, remain associated with the cells when the cells are suspended in a saline medium. If the cells are incubated in a medium containing 2
m
KCl, the cells are altered in some manner which permits most of the orthophosphate and approximately one-third of the polyphosphate to be subsequently eluted by osmotic shock. At lower salt concentrations, β-mercaptoethanol enhances this salt effect but is inactive by itself in this respect. At equivalent ionic strengths, the sodium salt of ethylenediaminetetraacetic acid behaves exactly like KCl or any other monovalent ionic compound in altering the cell to susceptibility to osmotic shock. No special effect of this anion at either high or low concentration could be detected. Resting cells are refractory to being altered in this manner by salts if an energy source, such as glucose, is included in the reaction mixture. Cells which are depleted of phosphate reserves will immediately incorporate phosphate when suspended in a medium containing inorganic phosphate and an energy source. These cells exhibit the phenomenon of “überkompensation.” In resting cells, the inclusion of KCl in the reaction mixture prevents the conversion of orthophosphate into polyphosphate and, also, gradually decreases the ability of the organism even to assimilate orthophosphate. This effect is reversible, however, since the cells will incorporate phosphate in a normal manner if the cells are transferred to a non-salinized medium, or if a nitrogen source is included in the salinized reaction mixture so that the cells are now in a medium adequate for growth.
Repair of Radiation-Induced Damage in
Escherichia coli
II. Effect of
rec
and
uvr
Mutations on Radiosensitivity, and Repair of X-Ray-Induced Single-Strand Breaks in Deoxyribonucleic Acid
Authors: Kapp Daniel S. , Smith Kendric C.
Published: January 2020

Strains of
Escherichia coli
K-12 mutant in the genes controlling excision repair (
uvr
) and genetic recombination (
rec
) have been studied with reference to their radiosensitivity and their ability to repair X-ray-induced single-strand breaks in deoxyribonucleic acid (DNA). Mutations in the
rec
genes appreciably increase the radiosensitivity of
E. coli
K-12, whereas
uvr
mutations produce little if any increase in radiosensitivity. For a given dose of X-rays, the yield of single-strand breaks has been shown by alkaline sucrose gradient studies to be largely independent of the presence of
rec
or
uvr
mutations. The
rec
+
cells (including those carrying the
uvrB5
mutation) could efficiently rejoin X-ray-induced single-strand breaks in DNA, whereas
recA56
mutants could not repair these breaks to any great extent. The
recB21
and
recC22
mutants showed some indication of repair capacity. From these studies, it is concluded that a correlation exists between the inability to repair single-strand breaks and the radiosensitivity of the
rec
mutants of
E. coli
K-12. This suggests that unrepaired single-strand breaks may be lethal lesions in
E. coli
.
Lipid Composition of
Chlamydia psittaci
Growth in Monkey Kidney Cells in Defined Medium
Authors: Makino S. , Jenkin H. M. , Yu H. M. , Townsend D.
Published: January 2020

The lipid compositions of (i) monkey kidney (MK-2) cells cultivated in Eagle's minimal essential medium (MEM) with 5% calf serum, (ii) MK-2 cells cultivated in Waymouth medium supplemented with 20 μg of sodium oleate and 2 mg of bovine albumin per ml, (iii)
Chlamydia psittaci
strain 6BC grown in the latter host system, and (iv) calf serum were compared. Strain 6BC contains 31% phosphatidyl ethanolamine (PE) and 15% phosphatidyl glycerol (PG), whereas the host cell contains almost the same amount of PE (27%) and no PG. A high concentration of total lipid was observed in strain 6BC (29 to 34%), whereas MK-2 cells contain only 9 to 15% and calf serum contains 4.5% total lipid. The fatty acids of the total lipid from strain 6BC contain branched-chain acids. These fatty acids were found mostly in PE (33.0%) and PG (37.0%). No branched-chain fatty acid was found in the MK-2 cells. There was an increase in triglyceride content when MK-2 cells cultivated in MEM (19.2%) were compared with cells cultivated in Waymouth medium (28.0%). A high concentration (62.0%) of octadecenoic acid (C18:1) was found in the triglyceride of MK-2 cells cultivated in Waymouth medium. The level of polyunsaturated fatty acids observed in MK-2 cells cultivated in Waymouth medium (10.8%) and in the chlamydiae grown in these cells (13.3%) was low compared with the level in MK-2 cells (28.8%) cultivated in MEM with 5% calf serum and the level in calf serum itself (50.8%). A higher ratio of sterol ester to free sterol was found in calf serum than in MK-2 cells or in chlamydiae. Host contribution to lipid composition of strain 6BC is discussed.
Pyrimidine-Specific Carbamyl Phosphate Synthetase in
Neurospora crassa
Authors: Williams Larry G. , Davis Rowland H.
Published: January 2020

Two carbamyl phosphate synthetases, the first an arginine-synthetic enzyme (CPS
arg
) and the second a pyrimidine-synthetic enzyme (CPS
pyr
), are shown to be present in
Neurospora
. The two enzymes can be separated on the basis of size and are distinguished by several different properties. Both CPS
pyr
and CPS
arg
have substrate requirements of adenosine triphosphate, HCO
3
−
, and
l
-glutamine, although NH
4
+
in high concentration will partially replace glutamine. CPS
pyr
activity can be completely inhibited by 5 × 10
−4
to 10 × 10
−4
m
uridine triphosphate (UTP). CPS
pyr
is cold-labile and can be protected against cold inactivation by UTP. The synthesis of CPS
pyr
and aspartate transcarbamylase (ATC), the initial enzymatic steps of the pyrimidine pathway, are co-derepressed by pyrimidine starvation. Mutations affecting CPS
pyr
and ATC all map at the same locus,
pyr-3
. Three classes of mutants with respect to the two activities were found: CPS
+
ATC
−
, CPS
−
ATC
+
, and CPS
−
ATC
−
. The distribution of these mutants on the genetic map, together with other data, indicate that the two activities are carried by a bifunctional protein.
Oxidation ofn-Tetradecane and 1-Tetradecene by Fungi
Authors: Allen J. E. , Markovetz A. J.
Published: January 2020

Cunninghamella blakesleeana(minus strain) and aPenicilliumspecies were grown in a mineral-salts medium containing eithern-tetradecane or 1-tetradecene as substrate, and ether extracts of the mycelial mats were analyzed for oxidation products. Extracts fromCunninghamellarevealed tetradecanoic acid and 13-tetradecenoic acid from the oxidation ofn-tetradecane and 1-tetradecene, respectively, thereby indicating that these hydrocarbons were subject to methyl group oxidation. In contrast toCunninghamella, thePenicilliumoxidized the two substrates by subterminal attacks on methylene rather than methyl groups. This was evidenced by tentative identifications of the following alcohols and ketones from oxidation of the hydrocarbons: tetradecan-2-ol, dodecan-1-ol, tetradecan-2-one, and tetradecan-4-one fromn-tetradecane, and tetradecen-4-ol, 13-tetradecen-4-ol, tetradecen-3-ol, 13-tetradecen-4-one, and tetradecen-3-one from 1-tetradecene. A pathway for hydrocarbon oxidation is proposed for subterminal oxidation at the methylene alpha to the methyl group.
Selective Outgrowth of Fimbriate Bacteria in Static Liquid Medium
Authors: Old D. C. , Duguid J. P.
Published: January 2020

Competitive mixed cultures were grown from inocula of a large number of bacteria of a genotypically nonfimbriate (
fim
−
) strain of
Salmonella typhimurium
and a small number of a genotypically fimbriate (
fim
+
) variant strain that formed type 1 fimbriae and had been derived from the
fim
−
strain by phage transduction. The
fim
+
strain differed from the
fim
−
strain in fermenting
l
-rhamnose (
rha
+
), and the viable
fim
+
and
fim
−
bacteria present in the cultures after different periods at 37 C were counted differentially in platings on rhamnose media. When the cultures were grown under aerobic static conditions in tubes of nutrient broth, the
fim
+
bacteria rapidly outgrew the
fim
−
bacteria, so that, although starting as a small minority (e.g., 1 in 10
7
), they approached or surpassed the number of the
fim
−
in 48 hr. A pellicle consisting of fimbriate bacteria was formed on the surface of the broth between 6 and 24 hr, and it is thought that the advantage of access to atmospheric oxygen enjoyed by these bacteria in the pellicle enabled them to outgrow the
fim
−
bacteria confined in the oxygen-depleted broth. The
fim
+
bacteria did not show selective outgrowth in mixed cultures grown in broth aerated by continuous shaking, in static broth incubated anaerobically in hydrogen, and on aerobic agar plates, i.e., under conditions not allowing an advantage from pellicle formation. The outgrowth of
fim
+
bacteria in aerobic static broth was prevented by the addition of α-methylmannoside, a substance that inhibits the adhesive and early pellicle-forming properties of bacteria with type 1 fimbriae. A motile flagellate (
fla
+
) variant of a
fim
−
fla
−
strain of
S. typhimurium
outgrew its parent strain in mixed cultures in aerobic static broth, but the selective advantage conferred by motility was weaker than that conferred by fimbriation.
Requirement of Adenosine 3′, 5′-Cyclic Phosphate for Flagella Formation in
Escherichia coli
and
Salmonella typhimurium
Authors: Yokota Takeshi , Gots Joseph S.
Published: January 2020

Adenosine-3′,5′-cyclic phosphate (cyclic AMP) is absolutely required for flagella formation and, hence, motility in cyclic AMP-deficient mutants of
Escherichia coli
and
Salmonella typhimurium
.
Lipids of
Rhizopus arrhizus
Fischer
Authors: Weete John D. , Weber Darrell J. , Laseter John L.
Published: January 2020

The lipids of
Rhizopus arrhizus
Fischer mycelia and sporangiospores were extracted, isolated, and separated by thin-layer, liquid, and gas chromatography. Structural confirmations of the compounds were made by a gas chromatographmass spectrometer combination. The
n
-heptane fraction contained squalene (1%) as a major hydrocarbon constituent. Other major lipid classes detected were free fatty acids, naturally occurring methyl esters of fatty acids, triglycerides, sterols, and polar lipids. The polar lipids (44.4%) were found in the highest concentrations, and the triglycerides (22.1%), sterols (16.7%), and free fatty acids (11.7%) were present in lesser concentrations. This is the first report of naturally occuring methyl esters of long-chain fatty acids being present in fungal mycelium. There appears to be a preference for incorporation of unsaturated acids into the complex lipids, with the exception of the triglycerides. The major saturated fatty acids in the mycelium were palmitic (C
16
) and arachidic (C
20
), whereas the major unsaturated acids were oleic (C
18:1
) and linoleic (C
18:2
), respectively.
Long-Term Starvation Survival of Rod and Spherical Cells of
Arthrobacter crystallopoietes
Authors: Ensign Jerald C.
Published: January 2020

Spherical and rod-shaped cells of
Arthrobacter crystallopoietes
, harvested during exponential growth, were subjected to total starvation for periods of time as long as 80 days. Viability measurements were made by plate count and slide culture procedures. Both cell forms remained 100% viable for 30 days. Thereafter, viability of rods and spheres decreased equally at a slow rate. After 60 days of starvation, more than 65% of both cell forms were viable. No significant cell lysis occurred as evidenced by microscopic examination, the small amount of 260-nm absorbing material found in the starvation buffer, and stability of radioactively labeled deoxyribonucleic acid in the cells. Endogenous respiration decreased 80-fold during the first 2 days of starvation, accompanied by a 30% decrease in dry weight of the cells. Thereafter, cellular carbon was oxidized to CO
2
at the constant level of 0.03%/hr over the remaining 78-day starvation period.
Galactose Transport in
Saccharomyces cerevisiae
III. Characteristics of Galactose Uptake in Transferaseless Cells: Evidence Against Transport-Associated Phosphorylation
Authors: Kuo Shou-Chang , Cirillo Vincent P.
Published: January 2020

The characteristics of the inducible galactose transport system in bakers' yeast were studied in uridine diphosphate, galactose-1-phosphate uridylyl-transferaseless cells. Transferaseless cells transport galactose at the same initial rate as wild-type cells and accumulate a mixture of free galactose and galactose-1-phosphate. The addition of
14
C-labeled galactose to cells preloaded with unlabeled galactose and galactose-1-phosphate results in a higher rate of labeling of the free-sugar pool than of the galactose-1-phosphate pool. These results support other evidence that galactose uptake in bakers' yeast is a carrier-mediated, facilitated diffusion and that phosphorylation is an intracellular event after uptake of the free sugar.
Rhodotorulic Acid from Species of
Leucosporidium, Rhodosporidium, Rhodotorula, Sporidiobolus
, and
Sporobolomyces
, and a New Alanine-Containing Ferrichrome from
Cryptococcus melibiosum
Authors: Atkin C. L. , Neilands J. B. , Phaff H. J.
Published: January 2020

An examination of 142 strains within 19 genera of yeasts and yeastlike organisms for formation of hydroxamic acids in low-iron culture showed production of hydroxamates by two unclassified strains and by 52 strains among the genera
Aessosporon
(3 of 3 strains),
Cryptococcus
(1 of 43),
Leucosporidium
(3 of 11),
Rhodosporidium
(4 of 4),
Rhodotorula
(27 of 39),
Sporidiobolus
(2 of 2), and
Sporobolomyces
(12 of 13). Crystalline rhodotorulic acid was isolated in amounts sufficient to account for most or all of the measured hydroxamate in culture supernatants of 16 strains representative of the five last-mentioned hydroxamate-producing genera. A new alanine-containing ferrichrome was isolated from one strain of
Cryptococcus melibiosum
. Rhodotorulic acid was a major metabolic product of many of the positive strains when grown in low-iron media, and iron was shown to repress its synthesis and excretion into the culture medium. The taxonomic significance of production of hydroxamic acids is described in connection with the position of these yeast species in the subclass
Heterobasidiomycetidae
.
Gene Mutation Eliminating Antimycin A-Tolerant Electron Transport in
Ustilago maydis
Authors: Georgopoulos S. G. , Sisler H. D.
Published: January 2020

A class of mutants of
Ustilago maydis
selected on a fungitoxic oxathiin lack of antimycin A-tolerant respiratory system which is present in wild-type cells. This system provides, directly or indirectly, for considerable resistance to antimycin A because growth of mutant cells lacking the system is much more sensitive to the antibiotic than that of the wild type. Antimycin A-sensitive O
2
uptake and growth is found in half of the progeny from crosses of mutant to wild type. All antimycin A-sensitive segregants are somewhat more resistant to oxathiins than the antimycin A-resistant segregants. The respiration of the mutant is strongly inhibited by cyanide and azide at concentrations which stimulate respiration of the wild type. Respiration of both mutant and wild type is about equally inhibited by rotenone. It appears that the mutation alters some component of the respiratory system located between the rotenone inhibition site and the antimycin A inhibition site that permits shift of electron transport to an alternate terminal oxidase when the normal electron transport pathway is blocked.
Molecular Events in the Growth Inhibition of
Bacillus subtilis
by
d
-Tyrosine
Authors: Champney W. Scott , Jensen Roy A.
Published: January 2020

The transformable strain of
Bacillus subtilis
strain 168 is extremely susceptible to growth inhibition by
d
-tyrosine. The molecular events associated with the inhibition of growth by
d
-tyrosine in this strain include the false feedback inhibition and probably the false repression of prephenate dehydrogenase. These effects were found to contribute to the formation of
d
-tyrosine-containing proteins by decreasing the intracellular concentration of
l
-tyrosine. Accordingly, growth inhibition of strain 168 by the
d
isomer of tyrosine was shown to be progressive, enduring, and delayed by prior growth on
l
-tyrosine. The synthesis of cellular macromolecules and viable cell count were progressively diminished in
d
-tyrosine-inhibited cultures. Several different enzyme activities were reduced after growth in the presence of
d
-tyrosine. Isotopic
d
-tyrosine was incorporated into cellular proteins without change of optical configuration. Long chains of cells with completed septa were observed microscopically, and therefore some cell wall effect may also be implicated.
Energy Generation and Utilization in Hydrogen Bacteria
Authors: Bongers L.
Published: January 2020

Studies on the relationship between cell synthesis and energy utilization in
Hydrogenomonas eutropha
have shown that the amount of oxidative energy required for synthetic reactions depends on the conditions of growth. The energy of hydrogen oxidation was most efficiently used when growth conditions were optimal (continuous culture, cells in exponential growth phase) and when the rate of growth was limited by H
2
or O
2
supply. Under these conditions, 2 to 2.5 atoms of oxygen were consumed by the oxyhydrogen reaction for the concomitant conversion of 1 mole of CO
2
to cell matter. This conversion efficiency, expressed as the O/C energyyield value, was observed with continuous cultures. A less efficient conversion was found with batch cultures. With limiting concentrations of CO
2
the rate of hydrogen oxidation was relatively high, and the O/C value was dependent on the growth rate. With nonlimiting concentrations of CO
2
, the rate of hydrogen oxidation was strictly proportional to the rate of CO
2
fixation, and the O/C value was independent of growth rate. This proportionality between the rate of H
2
oxidation and the rate of CO
2
fixation suggested that energy supply regulates the (maximum) rate of growth. From the energy-yield measurements, we concluded that the oxidation of 1 mole of H
2
yields the equivalent of 2 moles of adenosine triphosphate for
H. eutropha
, and that at least 5 moles of this high-energy phosphate is required for the conversion of 1 mole of CO
2
into cellular constituents.
Effects of Ribonucleosides on Thymidine Incorporation: Selective Reversal of the Inhibition of Deoxyribonucleic Acid Synthesis in Thymineless Auxotrophs of
Escherichia coli
Authors: Boyle James V. , Jones Marilyn E.
Published: January 2020

Addition of certain ribonucleosides to exponentially growing cultures of
Escherichia coli
increased the extent of thymidine incorporation. The prolonged uptake of thymidine was correlative with the ability of these ribonucleosides to prevent the degradation of thymidine. In addition to protecting thymidine, uridine reversed partially (70 to 80%) the inhibition of deoxyribonucleic acid (DNA) synthesis in thymineless auxotrophs by cytosine arabinoside, hydroxyurea, and nalidixic acid. This reversal was selective for auxotrophic strains since no reversal of inhibition by uridine was observed in any of the prototrophic strains examined. In the presence of uridine, the rapid assimilation of thymidine by prototrophic and auxotrophic strains was prevented and the rate of DNA synthesis became a function of the available exogenous thymidine. Under these conditions, prototrophic strains accumulated equivalent amounts of thymidine into the acid-soluble (pool) and acid-insoluble (DNA) cell fractions. In contrast, 95 to 98% of the thymidine taken up by auxotrophs was found in the acid-insoluble (DNA) cell fraction. The results suggest that different mechanisms for DNA synthesis exist in auxotrophs and prototrophs. Based on these observed differences, some possible mechanisms for the selective reversal of the inhibition of DNA synthesis in auxotrophs are discussed.
Rifampicin Inhibition of Ribonucleic Acid and Protein Synthesis in Normal and Ethylenediaminetetraacetic Acid-Treated
Escherichia coli
Authors: Reid Parlane , Speyer Joseph
Published: January 2020

The kinetics of ribonucleic acid (RNA) and protein synthesis in rifampicin-inhibited normal and ethylenediaminetetraacetic acid (EDTA)-treated
Escherichia coli
was measured. Approximately 200-fold higher external concentrations of rifampicin were needed to produce a level of inhibition in normal cells comparable to that observed in EDTA-treated cells. The rates of RNA and protein synthesis in both kinds of cells decreased exponentially, after an initial lag phase, at all rifampicin concentrations tested. The lag phase was longer and the final exponential slope less for protein synthesis than for RNA synthesis at a given rifampicin concentration. Below certain rifampicin concentrations, both the lag phase and the subsequent exponential decrease in the rates of RNA and protein synthesis were found to be rifampicin concentration dependent. At greater concentrations only the time of the lag phase was decreased by higher rifampicin concentrations, whereas the slope of the exponential decrease in the rates of RNA and protein synthesis was unaffected. In all cases, the exponential decrease continued to at least a 99.8% inhibition of the original rate of synthesis. These in vivo results are consistent with the mode of rifampicin action determined from in vitro studies; rifampicin prevents initiations of RNA polymerase on deoxyribonucleic acid, but not its propagation, by binding the enzyme essentially irreversibly. The results also indicate the size distribution of messenger RNA molecules in
E. coli
under our conditions.
Respiratory Metabolism of a “Petite Negative” Yeast
Schizosaccharomyces pombe
972h
−
Authors: Heslot H. , Goffeau A. , Louis C.
Published: January 2020

The respiratory metabolism of
Schizosaccharomyces pombe
972h
−
, a fission, haplontic, “petite negative” yeast, was studied. Glucose and glycerol are good growth substrates and are oxidized under appropriate conditions.
l
-Lactate, ethanol, malate, and succinate are oxidized but are poor substrates for growth.
d
-Lactate and pyruvate are neither oxidized nor used for growth. Limited growth was observed under anaerobic conditions. The addition of 0.3% KNO
3
to a rich medium relieves the oxygen requirement. A continuous increase of cell respiration during growth on repressive concentration of glucose was observed, suggesting the presence of glucose repression of respiration. Reduced nicotinamide adenine dinucleotide (NADH), succinate, α-glycerophosphate, and ascorbate plus tetramethyl-
p
-phenylenediamine are oxidized by a mitochondrial fraction. NADH and succinate oxidations are inhibited by antimycin A and NaCN but not by rotenone, suggesting the absence of the phosphorylation site I and the presence of sites II and III. The effects of several mitochondrial inhibitors on growth and respiration indicate that the requirement of an oxidant for growth is related neither to the functioning of the respiratory electron transport chain nor to the formation of respiratory energy. The previously suggested correlations between the nonviability of vegetative “petites” mutants, the absence of repression of respiration by glucose, and the incapacity to grow under anaerobic conditions are thus not strictly valid for
S. pombe
.
Segregational Respiratory-Deficient Mutants of a “Petite Negative” Yeast
Schizosaccharomyces pombe
972h
−
Authors: Heslot H. , Louis C. , Goffeau A.
Published: January 2020

No viable respiratory-deficient mutants of
Schizosaccharomyces pombe
972h
−
could be obtained by acriflavine and ethidium bromide treatments. These mutagens induce 15 to 70% of microcolonies which, after a growth-lag of a few days, further develop into normal, respiratory-competent colonies. These results suggest that unstable petites were induced. Segregational respiratory-deficient mutants resistant to cobalt sulfate inhibition were isolated. Some of these strains are deficient in cytochrome
a
+
a
3
and respire at low rates. The morphology of their mitochondrial membranes is modified: either the cristae are absent or they show aberrant concentric or tubular structures. Segregational mutants resistant to the respiratory inhibitors, 2,4-dinitrophenol or decamethylene diguanidine, were obtained. Neither mitochondrial structure nor function seems to be modified in these mutants. A segregational mutant resistant to benzimidazole inhibition does not grow on glycerol, although neither growth on glucose nor respiration appear to be affected.
Scanning-Beam Electron Microscopy of
Mycoplasma pneumoniae
Authors: Kammer Gary M. , Pollack J. Dennis , Klainer Albert S.
Published: January 2020

The morphology and the existence of a growth cycle of
Mycoplasma pneumoniae
have not been clearly established. There is disagreement as to whether this organism exists as a spherical or filamentous form, and whether it progresses from filamentous to spherical forms as the organism ages. A scanning-beam electron microscope (SEM) was utilized to provide detailed observations of the cycle of morphological changes during growth phases of
M. pneumoniae
. Cultures of cells grown and fixed in liquid suspension displayed morphological changes from spherical to filamentous and then to larger round forms. After 8 hr to 2 days of growth (phase I), spherical forms and aggregates were revealed. Two- to 6-day-old growth (phase II) was composed of both straight and branching filaments with bulbous elements situated at intervals along their lengths, and microcolonies composed predominantly of intertwined filaments. Six- to 10-day-old growth (phase III) was characterized by flattened, spherical organisms larger than those observed in phase I, occasional membranes or ghosts, and a paucity of aggregates or microcolonies. Thus, stereo-scan electron microscopic studies suggest that
M. pneumoniae
undergoes an orderly and sequential metamorphosis during its life cycle.
Effect of Low Temperature on the Growth and Fine Structure of
Bacillus subtilis
Authors: Neale E. Karol , Chapman George B.
Published: January 2020

Logarithmically growing cultures of
Bacillus subtilis
transferred from 37 to 15 C present atypical growth curves, and ultrathin sections of such cells reveal structural modifications involving mesosome deterioration and double cell wall formation. After a time, optical density and viable count increase, and cells regain the appearance typical of control cells, indicating a recovery from thermal stress. Subcultures of such recovered cells continue to grow well at 15 C. Cultures transferred from 37 to 12 C show atypical growth and fine structure, although no recovery from this stress is seen. Cultures previously grown at 15 C continue to grow at 12 C, and, furthermore, do not show the ultrastructural alterations seen in similar cells with a 37 C thermal history. The results of these studies suggest that low temperatures induce structural modifications in
B. subtilis
, that the response of a population to thermal stress may change during the period of the stress, and that thermal history may influence the response of a population to thermal stress.