bluuebunny/crossref_metadata_2025 huggingface dataset:
Mutator Factor in
Neisseria meningitidis
Associated with Increased Sensitivity to Ultraviolet Light and Defective Transformation
Authors: Jyssum Kaare
Published: January 2020

A variant of
Neisseria meningitidis
was found to carry a mutator factor which endowed the bacteria with generalized genetic instability. The reversion frequencies of several biochemical mutants were increased up to 1,000-fold when the factor was introduced. The factor is not unidirectional in preference, since the mutator induced mutants generally reverted with increased frequency in its presence. There could be found no indication of insufficient synthesis of nucleic acid precursors. Attempts to demonstrate an unusual, mutagenic base incorporated in deoxyribonucleic acid (DNA) were negative. Strains carrying the mutator factor had significantly increased sensitivity to ultraviolet light. A mutation to a more ultraviolet-resistant type coincided with a disappearance of the mutator property. The presence of the mutator factor in a competent strain resulted in a reduction of the transformation frequency to between 0.5 and 5% of that in the parental strain. A mutation to the more ultraviolet-resistant type resulted in simultaneous loss of the mutator property and reestablishment of a normal transformation efficiency. It has been suggested that this mutator factor may represent a defect in the DNA repair mechanism, which is also of importance for genetic recombination. The mutator factor showed cotransformation with the locus for streptomycin resistance, but a true linkage could not be proved.
Identification of Recombinant Chromosomes and F-Merogenotes in Merodiploids of
Escherichia coli
Authors: Herman Robert K.
Published: January 2020

Segregants from merodiploids heterozygous at two or more sites in the
lac
region were selected on the basis of containing a recombinant F-merogenote. Such recombinants frequently contained a recombinant chromosome as well. When the merodiploid was heterozygous at two sites, the frequency at which reciprocally recombinant chromosomes were present in the selected population was lower when the two marked sites were in the same gene and close together than when the sites were more widely separated. When the merodiploid was heterozygous at four sites and selection was made for an intragenic recombinational event, the recombinant chromosome was the reciprocal type about half the time and about half the time was not. Among the latter genotypes, most were nonrecombinant for the intragenic pair of markers. The data are consistent with a model in which recombination leads to the formation of two recombinant products, each containing a region of hybrid deoxyribonucleic acid.
Nucleotide Composition of Nuclear and Mitochondrial Deoxyribonucleic Acid of Fungi
Authors: Villa Vicente D. , Storck R.
Published: January 2020

The buoyant density of nuclear and mitochondrial deoxyribonucleic acid (DNA) from 14 species of fungi was determined by CsCl density gradient equilibrium centrifugation. The buoyant density of both types of DNA was the same for all three
Mucorales
analyzed. The buoyant density of mitochondrial DNA was significantly lower than that of the nuclear DNA for nine species of
Ascomycetes
and two species of
Basidiomycetes
. No simple correlation could be obtained from the comparison of the two types of DNA. Mitochondrial DNA represented a very small proportion of total DNA. Heat-denatured mitochondrial DNA renatured more readily than nuclear DNA.
Pneumonia Due to
Mycoplasma
in Gnotobiotic Mice IV. Localization and Identification of
Mycoplasma pulmonis
in the Bronchi of Infected Gnotobiotic Mice by Immunofluorescence and by Light Microscopy
Authors: Organick Avrum B. , Lutsky Irving I.
Published: January 2020

The model of pneumonia produced by intranasal inoculation of
Mycoplasma pulmonis
in gnotobiotic mice provided the opportunity to study the localization and identification of the infecting organisms in the tissues by immunofluorescence techniques. Frozen sections of pneumonic mouse lung were fixed in acetone, layered with rabbit anti-
M. pulmonis
serum, washed, layered again with fluorescein-isothiocyanate-labeled goat anti-rabbit globulin, washed again, and examined by fluorescence microscopy. A bright line of fluorescence was seen at the bronchial epithelial surface, usually in a continuous layer. Occasional masses of fluorescence were seen in the polymorphonuclear leukocytic exudate in the bronchial lumen. Sections of tissues fixed in Helle's or 10% Formalin fixatives and stained with hematoxylin and eosin were reviewed by light microscopy and revealed a zone of blue-staining material composed of tiny coccoid bodies in the same locations at the bronchial epithelial surface as in the immunofluorescent preparations and in previously reported electron microscope studies.
Immunological Studies on Dermatophytes III. Further Analyses of the Reactivities of Neutral Polysaccharides with Rabbit Antisera to
Microsporum quinckeanum, Trichophyton schoenleinii, Trichophyton rubrum, Trichophyton interdigitale
, and
Trichophyton granulosum
Authors: Grappel Sarah F. , Blank F. , Bishop C. T.
Published: January 2020

The serological reactivities of polysaccharides isolated from five species of dermatophytes,
Microsporum quinckeanum, Trichophyton granulosum, T. interdigitale, T. rubrum
, and
T. schoenleinii
, with rabbit antisera to these species were studied qualitatively by precipitation in gel and quantitatively by complement-fixation analyses. Significant differences in the serological reactivities of the galactomannans I were detected with antisera to
T. schoenleinii
and
T. interdigitale
. The differences appeared to be related to the specificity of these antisera for the galactofuranose residues in the polysaccharides. Antisera to
M. quinckeanum, T. granulosum
, or
T. rubrum
did not detect differences between the galactomannans I. The serological reactivities of the galactomannans II were different with each of the five antisera. The reactivities of the glucans could be correlated with the amount of α 1 → 6 linked glucopyranose residues when antisera to
T. schoenleinii
and
M. quinckeanum
were used.
Isoniazid Uptake in Relation to Growth Inhibition ofMycobacterium tuberculosis
Authors: Beggs William H. , Jenne John W. , Hall Wendell H.
Published: January 2020

14C-isoniazid (INH) was used to study the relationship between drug uptake or binding byMycobacterium tuberculosisand growth inhibition of the organism, which is dependent upon the concentration of drug and the duration of exposure. When strain H37Ra, grown in modified Sauton's liquid medium, was treated with 0.1 μg of INH per ml for 2 to 6 hr, followed by 10 μg of nicotinic hydrazide (NH) per ml to block further INH uptake, growth was retarded but not completely inhibited upon continued incubation. NH itself did not retard growth. However, cells treated in a similar manner with INH alone grew normally when diluted 1:100 in fresh, drug-free media. Uptake data showed that bacilli exposed to 0.1 μg of INH per ml accumulated 5.5, 9.7, and 12 mμg/mg of dry cells at 2, 4, and 6 hr, respectively. Other experiments suggested that once isoniazid is bound, it is not rapidly lost when NH is added or when the cells are diluted in fresh media. In the presence of 1.0 μg of INH per ml, tubercle bacilli took up 10 to 37 mμg/mg of dry cells in 20 to 90 min. These cells were not markedly inhibited when diluted 1:40 in fresh NH-containing media and incubated for 6 days. Growth inhibition of tubercle bacilli by INH depends on the uptake of sufficient drug, but the evidence obtained in this study suggests that the absolute concentration of bound INH is not as important in the action of the drug as is the maintenance of a critical cellular concentration for a requisite period of time.
Cytochrome
c
in
Hydrogenomonas eutropha
Authors: Fang Florence S. , Burris R. H.
Published: January 2020

A
c
-type cytochrome from
Hydrogenomonas eutropha
was purified 150-fold by butanol extraction, ammonium sulfate precipitation, and column chromatography. Three distinct
c
-type cytochromes were recovered which did not bind with either carbon monoxide or cyanide and hence did not appear to be denatured. Polyacrylamide gel electrophoresis indicated that one protein was acidic and the other two were basic. The acidic cytochrome
c
had a sedimentation coefficient of 3.46. Its amino acid composition was not markedly different from other bacterial cytochromes, but relative to mammalian cytochromes
c
it was low in lysine, threonine, and isoleucine and high in alanine and valine.
Formation of
O
-Ethylhomoserine by Bacteria
Authors: Murooka Yoshikatsu , Harada Tokuya
Published: January 2020

Resting cells of
Corynebacterium
sp. E17 formed
O
-ethylhomoserine from ethyl alcohol for a few hours. Addition of
l
-homoserine greatly enhanced its formation. Thus, the formation of
O
-ethylhomoserine from ethyl alcohol by 27 bacteria, 6 yeasts, and 4 fungi was investigated by using growing cultures and resting cells in the presence of
l
-homoserine. The
O
-ethylhomoserine formed in the culture supernatant fluids or supernatant fluids of the reaction mixtures was identified by paper chromatography. Many organisms which were incapable of forming
O
-ethylhomoserine with growing cultures formed it with resting cells. The formation of
O
-ethylhomoserine appears to be restricted to strains of
Brevibacterium, Corynebacterium, Bacillus, Mycobacterium, Nocardia
, and
Streptomyces
.
Effect of Substrate on the Fatty Acid Composition of Hydrocarbon- and Ketone-utilizing Microorganisms
Authors: Dunlap K. R. , Perry J. J.
Published: January 2020

The fatty acid pattern in hydrocarbon- and ketone-utilizing bacteria after growth on various substrates was examined. The fatty acid composition of one hydrocarbon-utilizing organism (
Mycobacterium
sp. strain OFS) was investigated in detail after growth on
n
-alkanes, 1-alkenes, ketones, and
n
-alcohols.
n
-Alkanes shorter than C
13
or longer than C
17
were not incorporated into cellular fatty acids without some degradation. Strain OFS incorporated C
14
to C
17
1-alkenes into cellular fatty acids as the ω-monoenoic fatty acid. Methyl ketones were incorporated into strain OFS after removal of one- or two-carbon fragments from the carbonyl end of the molecule. An organism isolated by enrichment on methyl ketones was incapable of
n
-alkane utilization but could grow on, although not incorporate, ketones or long chain
n
-alcohols into cellular fatty acids.
Regulation of Arginine and Proline Catabolism in
Bacillus licheniformis
Authors: Laishley E. J. , Bernlohr R. W.
Published: January 2020

The enzymes in the arginine breakdown pathway (arginase, ornithine-δ-transaminase, and Δ′-pyrroline-5-carboxylate dehydrogenase) were found to be present in
Bacillus licheniformis
cells during exponential growth on glutamate. These enzymes could be coincidentally induced by arginine or ornithine to a very high level and their synthesis could be repressed by the addition of glucose, clearly demonstrating catabolite repression control of the arginine degradative pathway. The strongest catabolite repression control of arginase occurred when cells were grown on glucose and this control decreased when cells were grown on glycerol, acetate, pyruvate, or glutamate. The proline catabolite pathway was present in
B. licheniformis
during exponential growth on glutamate. The proline oxidation and the Δ′-pyrroline-5-carboxylate dehydrogenase in this breakdown pathway were induced by
l
-proline to a high level. The Δ′-pyrroline-5-carboxylate dehydrogenase was found to be under catabolite repression control. Arginase could be induced by proline and arginine addition induced proline oxidation, suggesting a common in vivo inducer for these convergent pathways.
Utilization of Exogenous and Endogenous Ornithine by
Neurospora crassa
Authors: Davis R. H.
Published: January 2020

Through the use of a mutant deficient in ornithine-δ-transaminase (OTA), it is shown that this enzyme normally has no obligate or even major biosynthetic role in
Neurospora
. The pathways of ornithine and proline synthesis proceed wholly independently of each other in OTA-less strains. It is probable that OTA functions as an enzyme of arginine catabolism. With mutants affected in OTA, ornithine transcarbamylase, and the synthesis of ornithine, it was demonstrated that exogenous and endogenous ornithine are utilized in different ways. Exogenous ornithine is destined mainly for catabolism, whereas endogenous ornithine is destined mainly for biosynthesis. It is suggested that this distinction depends upon differences in the intracellular location or origin of the two sources of ornithine.
Regulation of Factors that Influence the In Vitro Stability of Tryptophan Synthetase from Yeast
Authors: Manney T. R.
Published: January 2020

The activity of tryptophan synthetase in crude extracts from
Saccharomyces cerevisiae
is stable if the cells are cultured in a complex medium, but extremely unstable if they are cultured in a minimal medium. The difference is not the result of different inherent properties of the enzyme formed in the two cultures. Rather, there are at least two kinds of macromolecular factors that influence the stability, one inactivating tryptophan synthetase and the other protecting against this inactivation. The abundance of these factors varies with the composition of the culture medium, which accounts for the differences observed.
Ratio of Teichoic Acid and Peptidoglycan in Cell Walls of
Bacillus subtilis
Following Spore Germination and During Vegetative Growth
Authors: Boylen Charles W. , Ensign Jerald C.
Published: January 2020

Cell walls were isolated from cells of
Bacillus subtilis
strain Marburg during synchronous outgrowth of spores, during the two synchronous cell divisions which followed, and at various times during exponential and early stationary growth. The amounts of teichoic acid and peptidoglycan components were determined in each cell wall preparation. The peptidoglycan is composed of hexosamine, alanine, diaminopimelic acid, and glutamic acid. The ratio of these was relatively constant in the cell walls at each stage of growth. The teichoic acid is composed of glycerol, phosphate, glucose, and ester-linked alanine. With the exception of glucose and ester-linked alanine, the ratios of these components were relatively constant throughout the growth cycle. There was a slight increase in the glucose content of the teichoic acid as the cells aged. There was no correlation between the amount of ester-linked alanine and the stage of growth. The ratio of teichoic acid (based upon phosphate content) to peptidoglycan (based upon diaminopimelic acid content) remained at nearly a constant level throughout the growth cycle. The conclusion is presented that these two cell wall polymers are coordinately synthesized during spore outgrowth and throughout the vegetative growth cycle.
Resistance ofEscherichia colito Penicillins V. Physiological Comparison of Two Isogenic Strains, One with Chromosomally and One with Episomally Mediated Ampicillin Resistance
Authors: Burman Lars G. , Nordström Kurt , Boman Hans G.
Published: January 2020

Two essentially isogenic strains ofEscherichia coliK-12 were compared: D31 had chromosomally and D1-R1 episomally mediated resistance to ampicillin. The two strains had the same ability to form colonies on ampicillin plates, but in other tests they were quite different. In serial dilution tests as well as in exponentially growing cultures, D1-R1 was far more resistant to ampicillin than was D31. The inoculum effect with D1-R1 was large and with D31 was rather small. On plates, D31 was more resistant to penicillin G than was D1-R1. The penicillinase activity of buffer suspended cells againstdl-ampicillin was 15 times higher for D1-R1 than for D31, but the two strains showed about the same rate of hydrolysis of penicillin G. Withdl-ampicillin as substrate, for D1-R1 the apparentKmwas 1.7 × 10−4m, whereas D31 gave a slightly sigmoid curve with a half-saturation concentration of about 5 × 10−3m. No induction of penicillinase activity was found. When the growth rate was varied by a factor of four, the amount of penicillinase per cell mass was constant in both D1-R1 and D31, whereas in two wild-type strains the amounts of penicillinase increased with increasing growth rates. With exponentially growing D1-R1, ampicillin disappearance started within 3 min, but at low ampicillin concentrations the rate was less than 10% of the rate of hydrolysis by buffer-suspended cells. Before D31 started hydrolysis, there was a lag period that lasted at least one generation and depended on the concentration of ampicillin. After this lag period, the rate of hydrolysis was 10 times higher than that observed with buffer-suspended cells. These differences between growing and nongrowing cells indicate that both the chromosomally and the episomally mediated penicillinases are controlled by some products present in growing cells.
Respiratory-deficient Mutants in
Saccharomyces lactis
Authors: Herman Alberta I. , Griffin Patricia S.
Published: January 2020

Six independent ultraviolet-induced respiratory-deficient mutants (petites) of
Saccharomyces lactis
were isolated and characterized. Two possessed a normal cytochrome spectrum, another displayed an increased level of all the cytochromes, and three suffered from a partial or complete loss of one or more of the cytochromes
a, b, c
, and
c
1
. All of the mutants were segregational petites; none was vegetative. Determination of linkage relationships between mutants was restricted because matings between mutants, homozygous or heterozygous, for loci affecting cytochrome content were blocked at various stages in the mating-sporulating sequence. At least three of the petites were genetically nonidentical. Three of the mutations appeared to occupy loci within the same linkage group; two of the three mutations that mapped within this region were cytochrome-deficient. Growth at high or low temperatures, under increased osmotic pressure or in media supplemented with various fatty acids or sterols, did not relieve the physiological defects in these mutants. Reasons for the differences in survival of segregational and vegetative petites within this species are examined.
Analysis of Melibiose Mutants Deficient in α-Galactosidase and Thiomethylgalactoside Permease II in
Escherichia coli
K-12
Authors: Schmitt Rüdiger
Published: January 2020

Three types of mutants (
mel
−
) unable to metabolize the α-
d
-galactoside, melibiose, were derived from
Escherichia coli
K-12. One type lacked α-galactosidase; another lacked a specific transport system, termed thiomethylgalactoside (TMG) permease II; and the third lacked both of these functions. The mutational sites were genetically mapped by recombination frequency with different markers and by determination of chromosomal transfer in interrupted-mating experiments. All three
mel
−
mutant types mapped in a cluster near to the
metA
marker on the
E. coli
chromosome and were cotransducible. Induction studies revealed that the three α-
d
-galactosides, melibiose, melibiitol, and galactinol, induced α-galactosidase and TMG permease II coordinately;
d
-galactose also induced them but only in a galactokinaseless mutant. These data suggest that α-galactosidase and TMG permease II may be components of a common operon.
Genetic and Biochemical Analysis of the Biotin Loci ofEscherichia coliK-12
Authors: Rolfe Barry , Eisenberg Max A.
Published: January 2020

Some 60 biotin auxotrophs ofEscherichia coliK-12 were isolated and classified into four groups according to their cross-feeding patterns, excertion products, and their ability to show a growth response to various biotin vitamers. Since all the mutants could be transduced with λdbiophages known to carry the entire bioAlocus, it was concluded that all of the mutation sites were located in this locus. It was also possible to derive a gene order for the different mutant groups on the basis of transduction studies with various λdbiophages that carry portions of thebioAlocus. A possible biochemical pathway for the biosynthesis of biotin inE. coliK-12 is discussed.
Properties of 5-Fluorouracil-containing Ribonucleic Acid and Ribosomes from
Bacillus subtilis
Authors: Saunders Priscilla P. , Bass R. E. , Saunders G. F.
Published: January 2020

Growth of a strain of
Bacillus subtilis
that requires uracil, thymine, adenine, and tryptophan in the presence of 5-fluorouracil (FU) results in the synthesis of ribonucleic acid (RNA) and ribosomes in which 55 to 65% of the RNA uracil has been replaced by the fluorine derivative. Examination of analogue-containing ribosomes by sucrose density gradient centrifugation and thermal denaturation studies suggests that, as far as the size, shape, and packing structure are concerned, extensive FU substitution has little or no effect. FU appears to replace uracil in RNA without selectivity for one RNA class over another, as determined by methylated albumin-kieselguhr column chromatography and sucrose density gradient centrifugation. The total amino acid content of the cells is markedly affected by growth in the presence of FU. The possibility of an FU effect on genetic translation is discussed.
Mycelial Phase ofParacoccidioides brasiliensisandBlastomyces dermatitidis: an Electron Microscope Study
Authors: Carbonell Luis M. , Rodriguez Joaquin
Published: January 2020

A comparative study of the mycelial phase ofParacoccidioides brasiliensisandBlastomyces dermatitidisreveals that both fungi are very much alike, containing multiple nuclei and nuclear pores, mitochondria, ribosomes, scarce endoplasmic reticulum, intracytoplasmic membrane systems, glycogen, and vacuoles. Shadowed cell walls show fine fibrillar surfaces that contrast with those in the yeast phase. The intracytoplasmic membrane system is continuous with the plasma membrane and is similar to bacterial mesosomes. Granules with light cores and dark rims are observed in the plasma membrane. Live hyphae growing inside a dead hypha are found much more frequently in immersed cultures than in solid-medium cultures, suggesting that breakage of the hypha could elicit this phenomenon.
Structures Containing Polyphosphate in
Micrococcus lysodeikticus
Authors: Friedberg Ilan , Avigad Gad
Published: January 2020

Granular structures containing inorganic polyphosphate were found in
Micrococcus lysodeikticus
. These structures were isolated by fractionation of the bacterial extract obtained by lysing the organisms with lysozyme. The composition of the fraction which was enriched with these structures was found to be: protein, 24%; lipids, 30%; and polyphosphate, 27%. This fraction also contained small amounts of ribonucleic acids, carbohydrate, and polyvalent cations. The effect of different reagents and enzymes on the integrity of the granules was examined. It was noticed that they accumulate in the bacteria during the logarithmic phase of growth but disappear gradually during the stationary phase.
Antibacterial Activity of the Purified Peroxidase from Human Parotid Saliva
Authors: Slowey R. R. , Eidelman S. , Klebanoff S. J.
Published: January 2020

The peroxidase of human parotid saliva has been purified by concentration, gel filtration on Sephadex G-200, and ion exchange chromatography on Amberlite CG-50. The purified product was devoid of amylase activity, lysozyme activity, and immunoglobulin A (IgA). However, it had an inhibitory effect on the growth ofLactobacillus acidophilusin complete growth medium and on lysine accumulation byL. acidophilusin a buffer-glucose medium, when combined with thiocyanate ions. The concentrations of peroxidase and thiocyanate ions employed were within the range found in saliva. The fractions which contained IgA did not have an anti-bacterial effect onL. acidophilusunder the conditions employed. Parotid saliva also contained low molecular weight inhibitors of peroxidase activity. These studies support the involvement of the salivary peroxidase in an antibacterial system in saliva.
Carboxylase Levels and Carbon Dioxide Fixation in Baker's Yeast
Authors: Cazzulo J. J. , Claisse L. M. , Stoppani A. O. M.
Published: January 2020

Levels of pyruvate carboxylase (PC), phosphopyruvate carboxylase (PEPC), and malate dehydrogenase (decarboxylating) were compared in wild-type bakers' yeast (I), a cytoplasmic-respiratory mutant (II), a biotin-deficient wild-type yeast (III), and a biotin-deficient respiratory mutant (IV). PC activities were greatly reduced in III and IV, whereas PEPC was reduced in II and IV. Malate dehydrogenase (decarboxylating) could not be detected in any of the yeasts. With yeast I growing on glucose as the sole carbon source, PEPC decreased to negligible levels during the logarithmic phase of growth (glucose repression effect), whereas PC increased. Both enzymes reverted to their original levels during the stationary phase, when glucose in the medium was exhausted. In agreement with the leading role of PC for CO
2
assimilation, the rates of
14
CO
2
fixation in yeasts I and II were approximately equal and were much higher than that in yeast IV. With I and II, most of the
14
C was distributed similarly in oxalacetate derivatives; with yeast IV, most of
14
C appeared in a compound apparently unrelated to CO
2
fixation via C
4
-dicarboxylic acids.
Isolation and Characterization of Three Autolytic Enzymes Associated with Sporulation of
Bacillus thuringiensis
var.
thuringiensis
Authors: Kingan Steven L. , Ensign Jerald C.
Published: January 2020

Cells of
Bacillus thuringiensis
containing refractile spores autolyzed readily when suspended in buffer. The autolysate contained enzymes which lysed vegetative cell walls of the organism. Three enzymes were isolated from the autolysate, and each was purified approximately 30-fold. One enzyme, most active near
p
H 4.0, was found to be an
N
-acetylmuramidase. The other two enzymes exhibited
p
H optima at 8.5. One was stimulated by cobalt ions and the other was not. The cobalt-stimulated enzyme was shown to be an
N
-acetylmuramyl-
l
-alanine amidase. The cobalt insensitive enzyme exhibited both
N
-acetylmuramyl-
l
-alanine amidase and endopeptidase activity. The amidase activity may reflect incomplete separation of the cobalt-stimulated enzyme. The endopeptidase cleaved the peptide bond between
l
-alanine
d
-glutamic acid. A cell wall lytic endopeptidase with this specificity has not been previously reported. All three enzymes were extremely limited in the range of bacterial cell walls which they attacked. Except for cell walls of
Micrococcus lysodeikticus
, which were lysed by the muramidase, only cell walls of members of the genus
Bacillus
were attacked.
Production of the Shwartzman Reaction with Microbial L Forms
Authors: Kalmanson George M. , Kubota Mike Y. , Guze Lucien B.
Published: January 2020

Study of potential pathogenicity of microbial L forms was done by the localized Shwartzman reaction. Stable L forms ofProteus mirabilisserved as skin preparation in rabbits for induction of Shwartzman reaction by subsequent intravenous injection of eitherP. mirabilisL forms orEscherichia coliendotoxin. The intensity of the reaction was positively correlated to numbers of L forms in the skin. L forms also served as the intravenous challenge. In vivo multiplication of L forms was not a prerequisite for the reaction, as it could be produced with nonviable, osmotically lysed L forms. The reaction produced with L forms in the skin was more intense than that produced with the parent bacterial form. These latter observations, coupled with the demonstration that L forms disappeared from the skin (lysed?) after 4 hr, in contrast to bacteria which were recoverable for 72 hr (duration of study), suggest release of endotoxin by L forms as a pathogenic mechanism.
Spontaneous Lethal Sectoring, a Further Feature of
Escherichia coli
Strains Deficient in the Function of
rec
and
uvr
Genes
Authors: Haefner K.
Published: January 2020

Eight recombination-deficient (Rec
−
) mutants of
Escherichia coli
were studied. Progeny lines were obtained on solid media, by means of micromanipulation, and the colony-forming ability of individual cells was analyzed. Cells of all eight strains gave rise to colony-forming as well as non-colony-forming descendants (“lethal sectoring”). Lethal sectors, i.e., groups of non-colony-forming cells which originate from a common ancestor, appeared with frequencies per generation ranging between 4 and 20% in Rec
−
strains, whereas lethal sectors were rare in Rec
+
strains (less than 1%). A strain carrying a mutation (
uvrA6
) in one of the genes involved in pyrimidine dimer excision from deoxyribonucleic acid (DNA) showed twice as many lethal sectors per generation as a strain with the genotype
uvrA
+
. Similarly, a double mutant (AB2480,
uvrA6, recA13
) showed twice as much spontaneous lethal sectoring as the corresponding Rec
−
strain (
uvrA
+
,
recA13
). The kinetics of growth curves obtained in nutrient broth and the frequency of non-colony-forming units in stationary-phase broth cultures indicate clearly that lethal sectors occur in liquid cultures too. The causes for spontaneous lethal sectoring are unknown at present. It seems reasonable to assume that gene
uvrA
and the
rec
genes are somehow involved in the repair of spontaneously occurring DNA lesions, since a deficiency in this type of repair may cause lethal sectors. The extent to which spontaneous lethal sectoring (observed in all Rec
−
strains of
E. coli
studied) may contribute indirectly to the failure to form recombinants is discussed.
Lipoidal Components of Bacterial Lipopolysaccharides: Nature and Distribution of Fatty Acids in
Aerobacter aerogenes
Authors: Gallin John I. , O'Leary William M.
Published: January 2020

The fatty acid distribution of
Aerobacter aerogenes
was studied by comparing the fatty acid composition of the lipoidal component of the endotoxin (lipid A) with the fatty acids of the readily extractable native lipids and total cellular fatty acids. The results for total cellular fatty acids and readily extractable native lipids were generally similar, but both quantitative and qualitative differences exist. In addition, profound differences between these two fractions and lipid A were observed. These differences included fewer fatty acids and lower concentrations of unsaturated and cyclopropane fatty acids in the lipid A. Hydroxy fatty acids persisted in the lipid A. The significance of these differences with respect to mammalian toxicity of endotoxins is discussed.
Biosynthesis of Vitamin B6by a Yeast Mutant
Authors: Pardini R. S. , Argoudelis C. J.
Published: January 2020

The gradient-plate technique was employed to isolate mutants ofSaccharomyces marxianus(NRRL-Y-1550) which, when grown in a synthetic culture medium, excreted about 2 μg/ml of vitamin B6as ascertained by microbiological assay. The major component that possessed vitamin B6activity was isolated by ion-exchange column chromatography and identified as pyridoxol by ultraviolet and fluorescence spectroscopy, as well as by paper chromatography and various chemical tests. Pyridoxal was also identified as one of the excreted compounds. Two other compounds that possessed vitamin B6activity were excreted in smaller quantities in the growth medium and have not yet been identified; they are not phosphates of vitamin B6. The amount of vitamin B6excreted was not increased when the mutant was grown in the presence of various oxidation products of this vitamin. The methods and results reported here may be helpful in future studies on the biosynthesis of vitamin B6.
Paraffin Oxidation in
Pseudomonas aeruginosa
I. Induction of Paraffin Oxidation
Authors: van Eyk J. , Bartels Trude J.
Published: January 2020

The induction of paraffin oxidation in intact cells of
Pseudomonas aeruginosa
was investigated. Oxidation of
14
C-heptane by cell-free extracts of adapted cells showed that the activity of whole cells is a reliable reflection of the synthesis of the first enzyme in the degradation of
n
-alkanes. Induction was significantly affected by glucose and could be completely repressed by malate. The amino acids
l
-proline,
l
-alanine,
l
-arginine, and
l
-tyrosine exhibited a rather low repressor action. Malonate, a nonrepressive carbon source, allowed gratuitous enzyme synthesis. A number of compounds which did not sustain growth were found to be suitable substitutes for paraffins as an inducer. Among these were cyclopropane and diethoxymethane. The induction studied under conditions of gratuity with the latter compound as an inducer showed immediate linear kinetics only at saturating inducer concentrations. With
n
-hexane as the inducer, a lag time was always observed, even when high concentrations were used.
Biochemical Homology Between Crystal and Spore Protein of
Bacillus thuringiensis
Authors: Somerville H. J. , Delafield F. P. , Rittenberg S. C.
Published: January 2020

The crystalline inclusion of
Bacillus thuringiensis
, dissolved in 8
m
urea containing 10% 2-mercaptoethanol and dialyzed to
p
H 8.3 to 8.5, was compared with a fraction obtained by the same extraction procedure from spores broken by dry rupture. The two fractions behaved similarly on chromatography with Sephadex G-100 and diethylaminoethyl cellulose. The preparations behaved identically on acrylamide gel electrophoresis at
p
H 12 and
p
H 9.5. Further, peptide maps of the two fractions obtained after digestion with trypsin were almost superimposable. Amino acid analyses of the crystal and spore fraction were closely similar; discrepancies are attributed to contamination of the spore extract with small amounts of other proteins. It is concluded that a significant portion of the spore protein is identical with the crystal protein.
Induction by Oxygen of Respiration and Phosphorylation of Anaerobically Grown
Escherichia coli
Authors: Cavari B. Z. , Avi-Dor Y. , Grossowicz N.
Published: January 2020

The changes occurring in the respiratory enzymes of anaerobically grown
Escherichia coli
strain B and
E. coli
15 T
−
A
−
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during exposure to oxygen were studied. Reduced nicotinamide adenine dinucleotide (NADH) oxidase activity reached its peak soon after O
2
exposure; cytochrome content and succinate oxidase activity increased more slowly, and these increases paralleled each other. The activities of isocitrate and malate dehydrogenases also increased, but the increase was less than that of the succinate and NADH oxidases; exposure to O
2
had no effect on the succinate and NADH dehydrogenase activities. On the other hand, the glycolytic activity decreased slowly after O
2
exposure. The incorporation of
32
P into acid-soluble organic phosphate esters paralleled the respiratory rate during the first 60 min after O
2
exposure, but continued to increase after the respiration reached a plateau. The sensitivity of
32
P incorporation to the uncoupler carbonyl cyanide
m
-chlorophenylhydrazone also increased with time. The observed relationship between the development of the respiratory chain and the energy-conserving mechanism during O
2
exposure is discussed. Synthesis of the respiratory enzymes upon exposure to oxygen was dependent on concomitant protein and ribonucleic acid synthesis but not on deoxyribonucleic acid synthesis.
Coresistance to Neomycin and Kanamycin by Mutations in an
Escherichia coli
Locus that Affects Ribosomes
Authors: Apirion D. , Schlessinger D.
Published: January 2020

Mutant strains resistant to neomycin or to kanamycin sulfate were isolated from
Escherichia coli
K-12. Nine mutants were analyzed; all were resistant to both antibiotics (about 150 and 100 μg/ml, respectively), and were designated
nek
. In the mutant strains, the ribosomes are changed from those of the parental strain; for when they were used in assays for polypeptide formation directed by polyadenylic acid or polycytidylic acid, coding fidelity in presence of the drugs was increased and inhibition of synthesis by the drugs was lessened. Mating experiments and transduction tests showed that all of the nine
nek
mutants are either closely linked or allelic, and the
nek
locus is closely linked to two genes—
str
(streptomycin) and
spc
(spectinomycin)—known to affect the 30
S
ribosome. The two
nek
mutants tested were recessive to the sensitive, wild-type allele. When the
nek
mutants were compared to the parental strain, pleiotropic effects of the
nek
mutations were observed. Resistance to low levels of streptomycin and spectinomycin was increased, whereas resistance to chloramphenicol was decreased. Also, the mutants were less able to adapt to high concentrations of lincomycin, and could no longer show phenotypic suppression of an arginine requirement by neomycin or kanamycin. Such pleiotropic effects are suggested to be the rule for mutations in genes that participate in the biosynthesis of a cellular organelle.
Intramolecular Heterogeneity of the Deoxyribonucleic Acid of Temperate Bacteriophages
Authors: Falkow Stanley , Cowie Dean B.
Published: January 2020

Spectral changes accompanying the thermal denaturation of phage deoxyribonucleic acid suggested that λ is not unique in possessing large-scale intramolecular heterogeneity and nucleotide clustering; instead, λ seems to share this property with other enteric phages.
Penetration-enhancing Factor Extracted from
Toxoplasma gondii
Which Increases Its Virulence for Mice
Authors: Lycke Erik , Norrby Ragnar , Remington Jack
Published: January 2020

Fractionation of extracts of disintegrated
Toxoplasma gondii
resulted in preparations which, when tested in cell cultures, enhanced penetration of host cells by this parasite. The influence of the preparations on the virulence of the RH strain and on two naturally avirulent strains for mice was studied simultaneously with the in vitro studies. It was demonstrated that the preparations increased the virulence of
Toxoplasma
. Mice inoculated with the preparation plus
Toxoplasma
suffered earlier morbidity and had a greater mortality rate than the control animals. There was a direct correlation between the effect of the preparations on the cell-penetrating capacity of the parasites and the increase in virulence for mice, indicating that the same mechanism is operative in both the in vivo and in vitro systems observed.
Toxicity ofPasteurella tularensisKilled by Ionizing Radiation
Authors: Landay Marshall E. , Wright George G. , Pulliam James D. , Finegold Milton J.
Published: January 2020

Approximately 2 × 1011viablePasteurella tularensiscells per ml, contained in suspensions, were killed by exposure to 106r of γ-radiation. When injected intraperitoneally into mice, the irradiated suspensions initially contained about 10ld50per ml, and immunized mice against challenge with fully virulent strains ofP. tularensis. Toxicity and immunizing activity of the suspensions decreased significantly within a few days at 5 C. Mice were protected against the toxin by immune serum or by prior injection of endotoxin ofEscherichia coli. Cortisone did not protect against the newly prepared suspension, but was effective against the aged suspension. Lethal doses of newly prepared suspension for guinea pigs and rabbits were approximately 0.5 ml and 2 ml, respectively. Cortisone protected rabbits, but not guinea pigs, against lethal challenge. Pyrogenic effects resembling those shown by endotoxin-containing suspensions were demonstrated in rabbits. The results suggested that two toxins are responsible for the toxicity of irradiated suspensions ofP. tularensis: one labile and associated with the immunizing activity of the suspension, the other more stable and resembling classical endotoxin.
Photosynthetic Membrane System in
Anacystis nidulans
Authors: Allen Mary Mennes
Published: January 2020

Cultures of
Anacystis nidulans
were grown under conditions of varying light intensity and temperature. Changes in pigment content were compared with changes in the fine structure of these cells. Pigment concentration and lamellar content varied inversely with the light intensity in cells grown with 100 and 1,000 foot candles of fluorescent light. Estimations of the relative area and volume of lamellae in cells showed that the amount of double membrane was directly proportional to the chlorophyll content of whole cells. Continuity of double membranes with cytoplasmic membrane was observed.
Lipolytic Esterases in Staphylococci
Authors: Saggers B. A. , Stewart G. T.
Published: January 2020

Staphylococci split a wide range of lipid substrates by production of an enzyme complex with two main components (i) a lipase acting optimally on fat-soluble glycerides, and (ii) an esterase acting optimally on water-soluble esters. The action is dependent upon carbon chain length, interfacial dispersion, solubility, and
p
H of substrate and end products. The esterase is less susceptible to organophosphorus inhibitors than mammalian esterases. There is no apparent correlation between lipolysis and markers of pathogenicity such as production of coagulase and toxin, but the possession of a flexible lipolytic mechanism might account for the persistence of staphylococci in the fatty secretions of mammalian skin.
Purification and Properties of Mutant and Wild-Type Diaphorases from
Diplococcus pneumoniae
Authors: Kreger Arnold S. , Olsen Ronald H.
Published: January 2020

Optochin-resistant mutant and wild-type diaphorases were purified approximately 300-fold by a combination of batch adsorption and column chromatography with diethylaminoethyl cellulose, and were characterized with regard to their
p
H optima, sensitivity to optochin inhibition and heat inactivation, Michaelis constants with flavine mononucleotide (FMN) and reduced nicotinamide adenine dinucleotide (NADH), and inhibition constants with optochin hydrochloride. The
p
H optima of the purified diaphorases were similar, but the purified diaphorases from the optochin-resistant strains were approximately four to five times more resistant to heat inactivation at 45 C than was the wild-type diaphorase. Purified diaphorase preparations from the optochin-resistant pneumococci had greater activities per milligram of protein and were more resistant to optochin inhibition than the preparation from the optochin-sensitive pneumococcus. Michaelis constants for FMN and NADH were similar; however, the inhibition constants of the optochin-resistant diaphorases were four to eight times greater than that of the optochin-sensitive diaphorase. Optochin hydrochloride produced a noncompetitive type of inhibition with FMN as substrate but a competitive type of inhibition with NADH as substrate. Optochin hydrochloride produced an approximately 10-fold increase in the Michaelis constant for NADH. The concentration of drug required to produce this effect was, however, greater with the mutant diaphorases than with the wild-type diaphorase. Optochin hydrochloride quenched the fluorescence of riboflavine. This phenomenon did not appear to be related to the diaphorase-inhibitory activity of the drug, however, since the
p
H requirements of the two reactions were different. Quenching of riboflavine fluorescence by optochin hydrochloride increased with a rise in
p
H, whereas inhibition of diaphorase activity by optochin hydrochloride was greater at
p
H 6.8 than at
p
H 7.6.
Cell Wall Composition of
Hyphomicrobium
Species
Authors: Jones H. E. , Hirsch Peter
Published: January 2020

Chemical analysis of cell walls obtained from
Hyphomicrobium
B-522 and from a morphologically and nutritionally distinct organism,
Hyphomicrobium neptunium
(ATCC 15444), showed that the organisms have a similar cell wall composition, which is typical of gram-negative bacteria. The walls of both strains contained many amino acids, including the characteristic mucopeptide components diaminopimelic acid and muramic acid. Isolation of the mucopeptide by use of sodium dodecyl sulfate was successful only with cell walls of
H. neptunium
, thus revealing a difference between the walls of the two strains. The mucopeptide preparation contained glucosamine, muramic acid, alanine, glutamic acid, diaminopimelic acid, and glycine in molar ratios of 1.05:1.21:1.84:1.0:1.04:0.31, respectively. The concentration of glycine was sufficiently high to suggest that it is a mucopeptide component rather than an impurity.
Location of Sulfate-binding Protein in
Salmonella typhimurium
Authors: Pardee Arthur B. , Watanabe Kimie
Published: January 2020

A method is described for location of proteins in bacteria. It depends upon two techniques. One technique is the inactivation of the protein by a reagent which is incapable of penetrating the bacterial membrane (permeability barrier). Proteins inside this membrane cannot be inactivated unless the cells are disrupted; proteins on or outside the membrane can be inactivated. The second technique depends upon inactivation of the protein by specific antibody. Antibody should not penetrate the external bacterial wall, and therefore should only inactivate proteins that are on the wall surface. Thus, proteins can be localized inside the membrane, in the wall-membrane area, or outside the wall. One reagent developed for use with the first technique is diazo-7-amino-1,3-naphthalene-disulfonate. It inactivated β-galactoside transport, but not β-galactosidase of intact
Escherichia coli
. Similarly, it inactivated sulfate binding and transport but not uridine phosphorylase activity of
Salmonella typhimurium
. This indicates that the sulfate-binding protein is on or outside the cell membrane, and that uridine phosphorylase is inside the cell. The organic mercurial compounds used also showed that the sensitive parts of the sulfate and α-methylglucoside transport systems are less reactive than the sensitive part of the β-galactoside system. Antibody to the sulfate-binding protein inactivated the purified protein but did not inactivate this protein when intact bacteria were employed. Thus, it appears that the sulfate-binding protein does not protrude outside the cell wall. The conclusion that the binding protein is located in the wall-membrane region is supported by its release upon spheroplast formation or osmotic shock, and also by its ability to combine with sulfate in bacteria which cannot transport sulfate into the cell.
Flagellar Synthesis inSalmonella typhimurium: Requirement for Ribonucleic Acid Synthesis
Authors: Aamodt L. W. , Eisenstadt J. M.
Published: January 2020

The micro-complement-fixation assay has been demonstrated to be a sensitive assay for flagella which occur in nanogram amounts. By use of this assay, it was found that flagellar synthesis occurs during starvation ofSalmonella typhimuriumfor tryptophan, an amino acid not present in flagellar protein. Under these conditions net ribonucleic acid (RNA) synthesis was reduced to approximately 10% of the control rate. Less than 1 μg of actinomycin D per ml further reduced RNA synthesis to less than 1% of the control rate in a culture sensitized by prior treatment for 5 min at 37 C with 5 × 10−4methylenediaminetetraacetate in 0.33mtris(hydroxymethyl)aminomethane-chloride (pH 8.0). In the presence of actinomycin D, no synthesis of flagellar protein could be detected. Analysis of fractions of RNA separated by zone centrifugation indicated that actinomycin D reduces the production of template RNA as well as of ribosomal RNA. This suggests that inS. typhimuriumthe production of flagellar protein requires the concomitant synthesis of RNA. There is no evidence that a stable messenger RNA specific for flagellar synthesis is present.
Mutation in Pneumococcus Type III Affecting Multiple Cistrons Concerned with the Synthesis of Capsular Polysaccharide
Authors: Bernheimer Harriet P. , Wermundsen Ingbritt E. , Austrian Robert
Published: January 2020

The genetic behavior in transformation reactions of 20 noncapsulated mutants of pneumococcus type III suggests that each has a single-site mutation in the locus controlling the synthesis of uridine diphosphate glucose (UDPG) dehydrogenase. Each strain is capable of yielding transformants of the binary capsular type SI-III when exposed to deoxyribonucleic acid (DNA) from type I cells. One additional mutant reacted differently and behaved as if it were a multisite mutant with the mutation affecting both the locus for UDPG dehydrogenase and that controlling the synthesis of high molecular weight type III capsular polysaccharide. When exposed to DNA from type I pneumococci, this strain yielded transformants which were genotypically binary but which expressed only the type I capsular phenotype.