bluuebunny/crossref_metadata_2025 huggingface dataset:
Characterization and Evaluation of a Soluble Antigen Complex Prepared from the Yeast Phase of
Histoplasma capsulatum
Authors: Reeves Michael W. , Pine Leo , Bradley Georgia
Published: January 2020

Soluble yeast-phase (YPS) antigen preparations (Reeves et al., 1972) were obtained from three strains of
Histoplasma capsulatum
. These were analyzed by agar-gel diffusion and complement fixation tests with human sera from known cases of histoplasmosis. Two of the preparations contained the H and M antigens normally found in histoplasmin, whereas the third preparation contained the H but not the M antigen. In addition, a group of unknown antigens, designated as the Y (yeast) antigens, were demonstrated in all three YPS preparations. On the basis of Sephadex gel filtration data, the molecular weight of the YPS M antigen was estimated to range from 117,000 to greater than 200,000; that of the YPS H antigen was estimated to range from about 60,000 to greater than 200,000; and that of the Y antigens was estimated to range from less than 10,000 to 100,000. Complement fixation tests with human homologous and heterologous sera showed that the Y antigens were specific for
H. capsulatum
; Y antigens were not detected in the single lot of histoplasmin used in this study. When 60 human histoplasmosis sera and serum samples from nine animals experimentally infected with
H. capsulatum
were analyzed, it was found that antibodies to the Y antigens occurred with about the same frequency as antibodies to the H antigen but with less frequency than that of antibodies to the M antigen. When used in rabbits as immunogens for the preparation of specific antisera to
H. capsulatum
, the components of the YPS preparations caused the formation of numerous cross-reacting antibodies. The data from this study show that the value of the YPS preparations for the serological diagnosis of histoplasmosis rests on the specificity of the H, M, and Y antigens and on the fact that the primary production of antibodies is restricted to these antigens in the course of natural infections. The YPS preparations were found to be stable for a period of at least 11 months under a variety of storage conditions and temperatures. Data obtained with various killing agents and metabolic inhibitors suggest an improved method for preparing the YPS antigens by using a suitable strain and killing the cells with iodoacetate.
Replication of Marek's Disease Virus in Cell Cultures Derived from Genetically Resistant Chickens
Authors: Sharma J. M. , Purchase H. G.
Published: January 2020

Various parameters of replication of Marek's disease virus (MDV) were studied in cells derived from genetically resistant (line 6) and susceptible (line 7) chickens. Cell-free and cell-associated preparations of three strains of pathogenic MDV (JM, GA, and Id-1) replicated equally well in cells of resistant and susceptible chickens. There were no demonstrable differences between the two genetic sources of cells for the chronological appearance and type of cytopathic effects and for the type of virus-induced antigens detectable by immunofluorescent and agar-gel precipitin tests. MDV propagated for about 4 weeks in cells of resistant line 6 chickens remained nonvirulent for line 6 and fully virulent for line 7 chickens. The lack of expression of genetic resistance to Marek's disease at cellular level contrasts the infection mechanisms of MDV from those of viruses associated with lymphoid leukosis in chickens.
Fluorescent Antibody Responses of Cases and Contacts of Hand, Foot, and Mouth Disease
Authors: Brown Gordon C. , O'Leary Theresa P.
Published: January 2020

Paired sera from clinical cases, familial contacts, and school contacts of hand, foot, and mouth disease were tested by indirect immunofluorescence against a strain of coxsackie A16 virus which had been adapted to human fibroblast tissue-cultured cells. All of the 22 clinical cases developed immunoglobulin (Ig) G antibodies, and 11 responded with IgM and 10 with IgA antibodies. Seventeen of 21 familial contacts of cases showed subclinical infection as determined by development of IgG antibodies. Only seven and nine, respectively, of these had demonstrable IgM and IgA antibodies. Thirteen of 16 school classmates of three clinical cases were shown to have experienced subclinical infection by the development of IgG antibodies. Only five had antibodies in the IgM fraction, and three had antibodies in the IgA fraction. A comparison of IgG titers with those obtained by neutralization tests provides further evidence that the indirect fluorescent antibody technique represents a rapid diagnostic procedure for this disease.
Mode of Action of Albocycline, an Inhibitor of Nicotinate Biosynthesis
Authors: Reusser Fritz
Published: January 2020

The antibiotic albocycline blocks the synthesis of nicotinate or nicotinamide in
Bacillus subtilis
cells. The inhibitory activity of the agent is fully reversed by nicotinic acid, nicotinamide, and, to a moderate extent, also by quinolinate. This suggests that in
B. subtilis
the antibiotic interferes with a reaction step occurring prior to the formation of quinolinate within the biosynthetic pathway leading to nicotinate.
Molecular Heterogeneity of Isolates of the Marine Bacterium
Leucothrix mucor
Authors: Kelly Michael T. , Brock Thomas D.
Published: January 2020

Two collections of strains of
Leucothrix mucor
were isolated, one of world-wide origin and the other originating from a restricted area around San Juan Island, Friday Harbor, Washington. These two collections were compared on the basis of morphological, nutritional, and physiological properties, deoxyribonucleic acid base composition, and mobility by starch-gel electrophoresis of isocitric dehydrogenase and malic dehydrogenase. Despite the fact that all the strains were similar in most characteristics, significant molecular heterogeneity was found in the enzyme electrophoresis studies. This heterogeneity was just as great in the local collection as it was in the world collection. Even strains originating from the same microenvironment exhibited molecular heterogeneity.
Immunological Analysis of Mycoplasma Membranes
Authors: Kahane Itzhak , Razin Shmuel
Published: January 2020

The antigens responsible for the production of antibodies toMycoplasma laidlawiiandM. gallisepticumcausing growth and metabolic inhibition of these organisms were localized in the cell membrane. Various membrane fractions were tested for serological activity. Membrane lipids were completely or almost completely inactive, whereas several preparations of defatted membrane proteins retained some serological activity, shown by their ability to stimulate metabolic inhibition antibody in rabbits and to adsorb metabolic inhibition antibody and form precipitation lines with an antiserum to the membrane. When the membranes were heated to 65 C for 1 hr, they virtually lost their ability to adsorb metabolic inhibition antibody, which suggests that the antigenic determinants are proteins. Serological activity was retained in reaggregated membranes obtained by dialysis against Mg2+of membranes solubilized in sodium dodecyl sulfate. The amount of solubilized membrane protein and lipid incorporated into the reaggregated membranes could be regulated by varying the Mg2+concentration. As the serological tests indicated that the various membrane antigens were selectively incorporated into the different reaggregated membranes, the use of controlled reaggregation of solubilized membranes is suggested as a new tool for the fractionation and antigenic analysis of membrane proteins.
Effect of Dihydrostreptomycin on Protein Synthesis in Whole Cells and in Cell-free Extracts of a Streptomycin-dependent Strain of
Escherichia coli
B
Authors: Dixon H. , Polglase W. J.
Published: January 2020

The effect of dihydrostreptomycin on the incorporation of amino acids into protein in antibiotic-deprived cells of a streptomycin-dependent strain of
Escherichia coli
B has been compared with its effect on protein synthesis in extracts from cells of the same strain. Stimulation of phenylalanine incorporation into protein in whole cells occurred within 5 min of addition of dihydrostreptomycin to a deprived culture and was maximal at an antibiotic concentration of 20 μg/ml. Stimulation of protein synthesis in cell-free extracts from antibiotic-deprived cells was maximal at a dihydrostreptomycin concentration of 10 μg/ml in systems programmed with f2-ribonucleic acid and poly AGU, whereas extracts from cells grown on nonlimiting concentrations of dihydrostreptomycin were unaffected by the addition of antibiotic. These results indicate that protein synthesis is an antibiotic-requiring process in streptomycin-dependent
E. coli
B.
Control of Cell Division in
Escherichia coli:
Experiments with Thymine Starvation
Authors: Donachie W. D.
Published: January 2020

This paper describes the kinetics of cell division in populations of cells which have been grown first under conditions which specifically inhibit deoxyribonucleic acid (DNA) synthesis (in the absence of thymine or the presence of nalidixic acid) and subsequently under conditions which allow DNA synthesis to recommence. Cell division does not take place during inhibition of DNA synthesis. There is a delay between recommencement of DNA synthesis and recommencement of cell division. The length of this delay increases as a function of the length of the preceding period of inhibition of DNA synthesis. The first division after this delay is partly synchronous, but all subsequent division is asynchronous. These observations are explained in terms of a model which supposes that the formation of initiator of chromosome replication during a period when DNA synthesis is inhibited results in a block to cell division. Division does not then occur until this “extra” round of DNA synthesis is completed.
Nature of Lactose-fermenting
Salmonella
Strains Obtained from Clinical Sources
Authors: Easterling S. B. , Johnson E. M. , Wohlhieter J. A. , Baron L. S.
Published: January 2020

Six of seven lactose-fermenting (
lac
+
)
Salmonella
strains obtained from clinical sources were found to be capable of transferring the
lac
+
property by conjugation to
Salmonella typhosa
WR4204. All of the six
S. typhosa
strains which received the
lac
+
property transferred it in turn to
S. typhimurium
WR5000 at the high frequencies typical of extrachromosomal F-merogenotes. These six
lac
elements were also transmissible from
S. typhosa
WR4204 to
Proteus mirabilis
and to some strains of
Escherichia coli
K-12; moreover, they were capable of promoting low frequency transfer of chromosomal genes from
S. typhimurium
WR5000 to
S. typhosa
WR4204. One of these
lac
elements was shown also to be capable of promoting low frequency chromosome transfer in
E. coli
K-12.
E. coli
K-12 strains harboring these
lac
elements exhibited sensitivity to the male specific phage R-17. Sensitivity to R-17 was not detected in
Salmonella
strains containing the elements. Examination of the
lac
elements in
P. mirabilis
by cesium chloride density gradient centrifugation showed that each element had a guanine plus cytosine content of 50%. The sizes of the elements varied from 0.8 to 3% of the total
Proteus
deoxyribonucleic acid. The amount of β-galactosidase produced by induced and uninduced cultures of
S. typhimurium
WR5000 and
S. typhosa
WR4204 containing the
lac
elements was lower than that produced by these strains with the F-
lac
episome. The heat sensitivity of β-galactosidase produced by the
lac
elements in their original
Salmonella
hosts indicated that the enzyme made by these strains differs from
E. coli
β-galactosidase.
Electrophoretic and Immunological Differences Between the Cytochrome
c
3
of
Desulfovibrio desulfuricans
and that of
Desulfovibrio vulgaris
Authors: Drucker Harvey , Campbell L. Leon
Published: January 2020

The cytochrome
c
3
of
Desulfovibrio desulfuricans
and that of
D. vulgaris
were purified to homogeneity as judged by disc gel electrophoresis and by ultracentrifugation. Both cytochromes had an oxidation-reduction potential of −205 ± 5 mv at
p
H 7.0 and showed characteristic absorption bands at 525 and 553 nm in the reduced state. The molecular weights of the two cytochromes (calculated from sedimentation and diffusion data) were similar, with values of 13,500 to 14,300 for
D. desulfuricans
and 13,800 to 14,700 for
D. vulgaris
. The two cytochromes differed in their electrophoretic properties on Geon and polyacrylamide gel electrophoresis and did not share a common precipitating antigenic determinant as judged by immunodiffusion data.
Penetration of
Pseudomonas aeruginosa
by Sodium Chloride and Its Relation to the Mechanism of Optical Effects
Authors: Matula Tibor I. , Macleod Robert A.
Published: January 2020

When cells of
Pseudomonas aeruginosa
were suspended in solutions containing increasing concentrations of NaCl, the optical density (OD) of the suspensions measured within 30 sec was found to increase in proportion to the increase in salt concentration. Measurement of intracellular fluid volumes indicated that the volume of the cells decreased roughly in proportion to the increase in salt concentration. After the initial increase in optical density, there was a slow decrease at all concentrations of NaCl tested except the highest, 500 m
m
. Metabolic inhibitors such as sodium azide and 2,4-dinitrophenol prevented the decrease. Direct analysis showed that the Na
+
and Cl
−
concentrations in the cells were 86 and 77%, respectively, of the concentrations of the ions in the suspending medium after 1 hr. Measurement of the
22
Na space in packed cells showed that Na
+
penetrated the total fluid space in the packed cells. The penetration of
22
Na was not prevented by the presence of metabolic inhibitors or by 500 m
m
NaCl in the suspending medium. The results indicate that the OD increases produced in suspensions of
P. aeruginosa
by NaCl are not due to the osmotic action of the salt. The subsequent optical density decreases observed are under metabolic control.
Relationship between Cell Wall, Cytoplasmic Membrane, and Bacterial Motility
Authors: Vaituzis Z. , Doetsch R. N.
Published: January 2020

High-resolution electron microscopy of polarly flagellated bacteria revealed that their flagella originate at a circular, differentiated portion of the cytoplasmic membrane approximately 25 nm in diameter. The flagella also have discs attaching them to the cell wall. These attachment discs are extremely resistant to lytic damage and are firmly bound to the flagella. The cytoplasm beneath the flagellum contains a granulated basal body about 60 nm in diameter, and a specialized polar membrane. The existence of membrane-bound basal bodies is shown to be an artifact arising from adherence of cell wall and cytoplasmic membrane fragments to flagella in lysed preparations. Based on structures observed, a mechanism to explain bacterial flagellar movement is proposed. Flagella are considered to be anchored to the cell wall and activated by displacement of underlying cytoplasmic membrane to which they are also firmly attached. An explanation for the membrane displacement is given.
Ultramicroscopic Structure of
Intrasporangium calvum
(
Actinomycetales
)
Authors: Lechevalier Hubert , Lechevalier Mary P.
Published: January 2020

The electron microscopic observation of vesicles formed by
Intrasporangium calvum
revealed that they do not contain spores. It thus seems that these vesicles should not be called sporangia. Isolation and study of three other strains of actinomycetes forming similar vesicles indicated that such structures can be formed by actinomycetes with very different properties. The taxonomic value of vesicle formation in actinomycetes is questioned.
Restriction in Genetic Crosses Between
Escherichia coli
and
Shigella flexneri
Authors: Falkow Stanley , Formal S. B.
Published: January 2020

Shigella flexneri
restricts
Escherichia coli
deoxyribonucleic acid (DNA) and can modify phage DNA so that it is restricted in
E. coli
.
Ultrastructural Studies on the Yeastlike and Mycelial Phases of
Sporotrichum schenckii
Authors: Lane James W. , Garrison Robert G. , Field Marvin F.
Published: January 2020

Fine details of the internal and external morphology of the yeastlike and mycelial phases of the dimorphic fungal pathogen
Sporotrichum schenckii
as seen in ultrathin sections are described and illustrated by electronphotomicrography. Comparisons of yeastlike phase ultrastructure were made using two different methods of fixation and embedding. The internal morphology of the two forms of yeastlike
S. schenckii
was in many ways similar to that of similarly dimorphic fungi and yeasts studied by other authors. However, the use of the glutaraldehyde-osmium in agar fixation technique suggests the presence of an electron transparent capsular or slime layer with associated electron dense microfibrils to be present external to the cell wall of the yeastlike phase but not the mycelial phase. Mycelial phase
S. schenckii
was found to contain many of the internal microstructures reported for other filamentous dimorphic fungi. Conidia production in agitated liquid culture was found to be restricted since only rare sessile conidia were observed.
Size-Separation of Yeast Mitochondria in the Zonal Centrifuge
Authors: Avers Charlotte J. , Szabo Arlene , Price Carl A.
Published: January 2020

Mitochondria, released from yeast spheroplasts and subjected to rate separation through sorbitol gradients in the zonal centrifuge, migrated in a wide symmetrical zone. Electron micrographs showed that the mitochondria had been resolved within the zone according to size. The mean mitochondrial diameter at the leading edge was approximately twice that at the trailing edge of the particle zone. Activities of the enzymes cytochrome oxidase, malate dehydrogenase, and reduced nicotinamide adenine dinucleotide- and
d
-lactate cytochrome
c
reductases were essentially uniform throughout the mitochondrial zone. Mitochondria from a vegetative-petite mutant had almost the same size distribution as the isogenic wild type, but with somewhat larger mean diameter and either absent or markedly reduced enzyme activities. Mixtures of wild-type and petite mitochondria produced sedimentation profiles showing overlap of particle populations with respect to mean sedimentation rates and mitochondrial diameters, as well as intermediate levels of enzyme activities. Both cristate and noncristate organelles were present throughout the mitochondrial zone from these mixtures. Mitochondria centrifuged in sorbitol density gradients were well-preserved and yielded consistent sedimentation profiles, whereas particles in sucrose density gradients migrated more slowly, produced varied sedimentation profiles, and often showed spurious peaks, presumably due to particle aggregations.
Enhancement of the Lethal Effects of Endotoxins by Interferon Inducers
Authors: Huang Kun-Yen , Landay Marshall E.
Published: January 2020

Prior treatment of mice with poly I:C or NDV enhanced the lethal effect of
E. coli
or
B. dermatitidis
endotoxins.
3-Phosphoserine Transaminase Mutants of
Escherichia coli
B
Authors: Dempsey Walter B.
Published: January 2020

Mutants lacking 3-phosphoserine:oxoglutarate transaminase require pyridoxine and serine for growth.
Hydrogen Metabolism by
Rhodomicrobium vannielii
Authors: Hoare Derek S. , Hoare S. Louise
Published: January 2020

Under appropriate cultural conditions, cell suspensions of
Rhodomicrobium vannielii
effect two distinct photoreactions involving molecular hydrogen: (i) the photoreduction of carbon dioxide, and (ii) the photoproduction of hydrogen.
Simplified Method for Testing Mutagens in
Saccharomyces
Authors: Fink Gerald R. , Lowenstein Robert
Published: January 2020

Pretreatment of yeast auxotrophs with mutagen on complete medium stimulates the reversion frequency.
Stabilization of Colicin E2 by Bovine Serum Albumin
Authors: Mitusi Etsuko , Mizuno Den'Ichi
Published: January 2020

Colicin E2 was partially purified from
Escherichia coli
W3110. This preparation was remarkably stabilized by bovine serum albumin in a solution at neutral
p
H, as shown by dilution experiments and tests on heat stability of colicin. One killing unit of colicin E2 was estimated to correspond to one molecule of colicin E2, on the assumption of a molecular weight of 60,000.
Effect of Carbon Dioxide on the Aspartic Acid Requirement for Proteinase Biosynthesis by
Streptococcus faecalis
var.
liquefaciens
Authors: Welch Peter C. , Hartman Ronald E.
Published: January 2020

Non-proliferating cells of
Streptococcus faecalis
var.
liquefaciens
required aspartic acid for proteinase biosynthesis in the absence of CO
2
but not in the presence of CO
2
.
Mutants of Yeast with Altered Oxidative Energy Metabolism: Selection and Genetic Characterization
Authors: Parker John H. , Mattoon James R.
Published: January 2020

Isolation of a series of mutants, characterized by decreased ability to utilize nonfermentable carbon sources for growth and presence of all cytochromes, is reported. A total of 161 mutants, showing deficient growth on glycerol but able to reduce 2,3,5-triphenyltetrazolium chloride, were isolated, purified, and characterized by ability to grow on various carbon sources. Mutants showing decreased growth were examined by low-temperature spectroscopy, and the 35 strains shown to possess all cytochromes were retained for further studies. These strains were characterized by growth on various nonfermentable carbon sources, relative yield on glucose medium, and respiration (Q

O
2

) of glucose and ethyl alcohol. Genetic studies revealed that at least 19 of the 35 mutants are the result of mutation in single nuclear genes. Furthermore, at least 11 complementation groups are represented among these 19 mutants. Mutants within two complementation groups were shown to be very similar in various properties. These studies demonstrate that a large number of nuclear genes control oxidative energy metabolism and that the characteristics of mutants of the general class are extremely diverse.
Control of Synthesis of Malate Dehydrogenase in
Aerobacter aerogenes
Authors: Yashphe Jacob
Published: January 2020

An inverse linear relationship was observed between the levels of
l
-malate dehydrogenase (MDH) and growth rates of
Aerobacter aerogenes
when grown under aerobic and anaerobic conditions on various substrates which served as the sole carbon and energy sources. Deviations from this linearity were found. MDH levels of cells grown aerobically on oxalacetate,
l
-malate,
d
-mannose and
d
-galactose, and of cells grown anaerobically on
l
-malate and
d
-mannose were higher than those expected according to this relationship. Enzyme levels of cells grown aerobically on maltose,
d
-glucuronate, pyruvate, and possibly melibiose and sucrose were lower than the expected ones. Experiments in which the cells were grown on a mixture of two substrates showed that substrates which gave low levels of MDH repressed the synthesis of this enzyme even in the presence of
l
-malate or other “high-level substrates.” Repressed levels were also observed when the mixture contained
l
-malate together with “intermediate” or high-level substrates. Identical MDH patterns were obtained by acrylamide gel electrophoresis for all the enzymatic preparations.
Specific Loss of Newly Replicated Deoxyribonucleic Acid in Nalidixic Acid-Treated
Bacillus subtilis
168
Authors: Ramareddy Guntaka , Reiter Harvard
Published: January 2020

Bacillus subtilis
168
thyA, thyB
cells degrade and lose from 20 to 30% of their deoxyribonucleic acid (DNA) in 3.5 hr of exposure to 20 μg of nalidixic acid per ml. Degradation appears to be initiated at the replication point and to proceed sequentially along the chromosome from the most recently synthesized DNA to “older” DNA. Both DNA strands appear to be degraded equally, and essentially all of the products of degradation are soluble in cold acid.
Properties of Threonine Deaminase From a Bacterium Able to Use Threonine as Sole Source of Carbon
Authors: Lessie T. G. , Whiteley H. R.
Published: January 2020

A threonine deaminase susceptible to inhibition by isoleucine was purified over 3,000-fold from extracts of
Pseudomonas multivorans
, a bacterium able to use threonine or α-ketobutyrate as sole source of carbon and energy. The enzyme was characterized with respect to molecular weight, dissociation to subunits, and apparent affinities for threonine, isoleucine, and several other ligands. Certain features of the enzyme including its reversible dissociation to subunits, its high constitutive activity, its marked stability, and high apparent orders of binding for threonine and isoleucine were unusual compared to those of isoleucine-inhibitable enzymes from other bacteria. These findings suggested some relationship between properties of the enzyme and the ability of
P. multivorans
to use threonine as sole carbon source. However, mutant studies ruled out a direct role of the enzyme in threonine catabolism and indicated that another enzyme, threonine dehydrogenase, is essential for growth on threonine.
Reductive Pentose Cycle and Formate Assimilation in
Rhodopseudomonas palustris
Authors: Stokes Jean E. , Hoare Derek S.
Published: January 2020

Rhodopseudomonas palustris
assimilated formate autotrophically as carbon dioxide and hydrogen arising from the activity of the formic hydrogenlyase system. Kinetic analyses of cell suspensions pulse-labeled with
14
C-formate or
14
C-bicarbonate showed similar distributions of incorporated radioactivity. In both cases phosphate esters were the first assimilation products. Ribulose diphosphate carboxylase, phosphoribose isomerase, and phosphoribulokinase, characteristic enzymes of the reductive pentose cycle, were present in extracts of cells grown on formate.
Genetic Analysis of Recombination-Deficient Mutants of
Escherichia coli
K-12 Carrying
rec
Mutations Cotransducible with
thyA
Authors: Willetts Neil S. , Mount David W.
Published: January 2020

The
rec
mutations carried by 20 strains of
Escherichia coli
K-12 which are defective in genetic recombination and sensitive to ultraviolet light and X rays, and whose λ lysogens show spontaneous phage production, have been mapped near
thyA
. In 15 of the strains, the
rec
mutation fails to complement
recB21
but complements
rec-22
. The other five strains carry a
rec
mutation which complements
recB21
but not
rec-22
. These mutations map closer to
thyA
than those which fail to complement
recB21
. They therefore appear to be defective in a different recombination gene, denoted
recC
. The order of
recB
and
recC
on the linkage map of
E. coli
K-12 is
thyA-recC-recB-argA
.
Killing of
Haemophilus influenzae
Cells by Integrated Ultraviolet-Induced Lesions from Transforming Deoxyribonucleic Acid
Authors: Beattie Kenneth L. , Setlow Jane K.
Published: January 2020

Highly competent cultures of
Haemophilus influenzae
are inactivated by exposure to transforming deoxyribonucleic acid (DNA) irradiated with ultraviolet light (UV). As a function of UV dose to the DNA, the killing goes to a maximum and then decreases. The killing of
H. influenzae
by unirradiated
H. parainfluenzae
DNA, reported by other workers, is enhanced by low doses of UV, but drops off at high doses. Since there are no such lethal effects in a strain of
H. influenzae
that takes up DNA normally but does not integrate it, it is concluded that the killing is associated with integrated UV lesions. All the killing of wild-type cells due to irradiated DNA is eliminated by photoreactivation of the DNA. The killing of an excisionless strain of
H. influenzae
, however, is not eliminated by maximal photoreactivation of the irradiated transforming DNA. The nonphotoreactivable fraction of killing in the excisionless strain increases with increasing dose. The kinetics of the killing-dose curves may be explained only partially in terms of UV-induced loss of integration. It is postulated that the number of pyrimidine dimers relative to other DNA components integrated decreases at higher UV doses.
Alterations in the Phospholipid Composition of
Escherichia coli
B During Growth at Different Temperatures
Authors: De Siervo August J.
Published: January 2020

The major phospholipid classes of
Escherichia coli
B, phosphatidyl ethanolamine, cardiolipin, and phosphatidyl glycerol, were quantitated at different stages of the growth cycle. The organisms were incubated at both 27 and 37 C. Significant differences were observed both in the amounts of total lipid phosphorus per gram (dry weight) of cells and in the relative percentages of the individual phospholipids. At 37 C the total amount of lipid phosphorus decreased significantly throughout the growth cycle. However, at 27 C total lipid phosphorus accumulated. The patterns of the three major phospholipid classes of
Escherichia coli
exhibited complex quantitative changes. In addition, some evidence based on glycerol to phosphate molar ratios indicated that phosphatidyl glycerolphosphate replaced phosphatidyl glycerol during the late growth stages of
E. coli
B when grown at 27 C. A comparative analysis of phospholipid and fatty acid patterns led to a hypothesis attempting to explain some reported variations in the lipid composition of
E. coli
under different conditions of growth.
Induced Salt Sensitivity in Fungal Cells and Its Reversal by Imidazole Derivatives
Authors: Fries Nils
Published: January 2020

The sensitivity to Cl
−
and Br
−
induced by heat shock of cells of
Ophiostoma multiannulatum
and of
Rhodotorula glutinis
could be partially reversed by histidine and some other imidazole derivatives.
Preparation and Storage of Single Spores of
Saccharomyces cerevisiae
Authors: Rousseau P. , Halvorson H. O.
Published: January 2020

A method is described for large-scale isolation and storage of single spores of
Saccharomyces cerevisiae
.
Effects of Supersuppressor Genes on Enzymes Controlling Lysine Biosynthesis in
Saccharomyces
Authors: Fjellstedt Thôrsten A. , Ogur Maurice
Published: January 2020

Yeast supersuppressor genes capable of masking the effects of several lysine mutant genes (
ly
1-1
,
ly
9-1
,
ly
2-1
) were studied with respect to their effects on the respective enzymes (saccharopine dehydrogenase, saccharopine reductase, and α-amino-adipic acid reductase). In all strains tested, the supersuppressors functioned by allowing enzyme synthesis not found in the unsuppressed mutant. Studies by optical methods of saccharopine dehydrogenase and saccharopine reductase extracted from suppressed
ly
1-1
and
ly
9-1
cells, respectively, revealed that the
K
m
values for these enzymes were significantly greater than those found in wild type. Saccharopine dehydrogenase from suppressed
ly
9-1
cells was found to have
K
m
values similar to wild type. These findings are consistent with the inference that a supersuppressor may act by enabling nonsense codons to be read, producing altered enzyme protein. Recent findings that lysine degradation in mammals may involve saccharopine and that the human diseases, hyperlysinemia and saccharopinuria, may be due to metabolic blocks in this route of lysine degradation suggest the
ly
1-1
and
ly
9-1
yeast mutants as models for the human condition and its possible euphenic treatment.
Incorporation of 5-Diazouracil-
2
-
14
C
into Ribonucleic Acids of
Escherichia coli
During Division Inhibition
Authors: Previc Edward , Fister George
Published: January 2020

Radioactive diazouracil (DZU-
2
-
14
C
) was rapidly incorporated into acid-insoluble material of
Escherichia coli
B. Isolated ribonucleic acid contained essentially all of the incorporated label, and this was solubilized by ribonucleases but not by deoxyribonuclease. A maximum of 45 to 50% of added label was incorporated at division-inhibitory and subinhibitory concentrations. Incorporation levels and filament-forming capacity were concomitantly depressed by preincubation of DZU in various medium components. The lower levels of incorporation brought about by preincubation were apparently related to an inherent instability or high reactivity of the DZU. The limit on incorporation of fresh DZU suggests the presence of geometrical isomers in the original DZU. The nature of these isomers and the reactivity of DZU are discussed in relation to its use in future cell division studies.
Regulation of the
Escherichia coli
Tryptophan Operon by Early Reactions in the Aromatic Pathway
Authors: Held William A. , Smith Oliver H.
Published: January 2020

7-Methyltryptophan (7MT) or compounds which can be metabolized to 7MT, 3-methylanthranilic acid (3MA) and 7-methylindole, cause derepression of the
trp
operon through feedback inhibition of anthranilate synthetase. Tyrosine reverses 3MA or 7-methylindole derepression, apparently by increasing the amount of chorismic acid available to the tryptophan pathway. A mutant isolated on the basis of 3MA resistance (
MAR
13) was found to excrete small amounts of chorismic acid and to have a feedback-resistant phenylalanine 3-deoxy-
d
-arabinoheptulosonic acid-7-phosphate (DAHP) synthetase. Genetic evidence indicates that the mutation conferring 3MA resistance and feedback resistance is very closely linked to
aroG
, the structural gene for the DAHP synthetase (
phe
). Since feedback inhibition of anthranilate synthetase by
l
-tryptophan (or 7MT) is competitive with chorismic acid, alterations in growth conditions (added tyrosine) or in a mutant (
MAR 13
) which increase the amount of chorismic acid available to the tryptophan pathway result in resistance to 7MT derepression. Owing to this competitive nature of tryptophan feedback inhibition of anthranilate synthetase by chorismic acid, the early pathway apparently serves to exert a regulatory influence on tryptophan biosynthesis.
Surface Structure of Streptomycete Spores as Revealed by Negative Straining and Freeze-Etching
Authors: Wildermuth H.
Published: January 2020

The application of a simple negative staining technique and freeze-etching has revealed detailed information on the species-specific surface structure of spores and aerial hyphae of streptomycetes.
Incorporation of Uridine into
Bacillus subtilis
and SPP1 Bacteriophage Deoxyribonucleic Acid
Authors: Barlati Sergio
Published: January 2020

Tritiated uridine is incorporated into the deoxyribonucleic acid of
Bacillus subtilis
and bacteriophage SPP1; the tritium is recovered in the cytidine moiety of both deoxyribonucleic acids.
Carbohydrate Accumulation During the Sporulation of Yeast
Authors: Roth Robert
Published: January 2020

The sporulation of
Saccharomyces cerevisiae
is characterized by an increase in dry weight without cell division. At least 67% of the dry weight increase is due to the synthesis of cellular carbohydrates consisting of trehalose and insoluble components. The insoluble carbohydrates accumulate only during the period preceding the actual formation of visible ascospores. The trehalose accumulates throughout the sporulation cycle and is specifically localized in the ascospore.
Taxonomy of Phytopathogenic Pseudomonads
Authors: Sands D. C. , Schroth M. N. , Hildebrand D. C.
Published: January 2020

Phytopathogenic pseudomonads were placed into four major groups on the basis of nutritional and physiological characteristics. Group I consists of 86 strains of phytopathogens distinguishable from other fluorescent pseudomonads by low growth rates, ability to induce hypersensitivity on tobacco, absence of arginine dihydrolase, and relatively limited ranges of carbon sources. Most of these strains cannot utilize benzoate, 2-ketogluconate, spermine, β-alanine,l-isoleucine,l-valine, andl-lysine. Most of the organisms in group I clustered into a small number of subgroups, each of which generally corresponded to a previously recognized nomenspecies. These subgroups differ with respect to the number of substrates used. As a rule, the organisms that utilize the fewest substrates have the most limited host ranges. The fluorescent pseudomonads of group II are arginine dihydrolase-positive and utilize a considerably larger number of carbon sources. Most pathogens of group II are similar toPseudomonas fluorescensbiotype A. Groups III and IV consist of nonfluorescent pseudomonads. These two groups can be distinguished by the number of carbon sources used and by pigmentation. An amended description of the flurescent pseudomonads and their internal subdivision is presented.
Autotrophic and Heterotrophic Metabolism of
Hydrogenomonas:
Regulation of Autotrophic Growth by Organic Substrates
Authors: Stukus Philip E. , DeCicco B. T.
Published: January 2020

The effects of a number of organic substrates on the autotrophic metabolism of
Hydrogenomonas eutropha
were examined. Dual substrate (mixotrophic) cultivation in the presence of hydrogen plus either fructose or alanine allowed autotrophic growth to begin immediately after the exhaustion of the organic substrate. On the other hand, the presence of acetate, pyruvate, or glutamate caused a lengthy lag to occur before autotrophic growth commenced. With acetate or pyruvate this lag (plateau) in the dicyclic growth curve was due to the repression of ribulose diphosphate carboxylase (RDPC) synthesis during mixotrophic growth. During heterotrophic growth with glutamate, RDPC was partially repressed; however, during mixotrophic growth, RDPC activity was high. Thus the delay of autotrophic growth was not due to a repression of RDPC by glutamate. The data suggest that glutamate interferes with autotrophic metabolism by repressing the incorporation of inorganic nitrogen. The repression of these vital autotrophic functions by acetate, pyruvate, and glutamate occurred both in the presence and absence of hydrogen, i.e., during both heterotrophic and mixotrophic cultivation. The derepression of the affected systems during the plateau phase of the dicyclic growth curves was demonstrated. Carbon dioxide assimilation by whole cells agreed well with the RDPC activity of extracts from cells grown under similar conditions.
Competent
Diplococcus pneumoniae
Accept Both Single- and Double-Stranded Deoxyribonucleic Acid
Authors: Miao Raymond , Guild W. R.
Published: January 2020

The transforming activity of fractionated complementary strands of
Diplococcus pneumoniae
deoxyribonucleic acid (DNA) bands at the position of fully denatured DNA in CsCl at
p
H 11.0, and is completely (> 99.8%) destroyed by digestion with exonuclease-I. These results prove that pure single strands transform the normally prepared competent cells of this species. Their efficiency is about 0.5% that of native DNA of comparable size.
Low-
p
H Activation of
Bacillus cereus
Spores
Authors: Issahary Gabriela , Evenchik Z. , Keynan A.
Published: January 2020

Heat activation of bacterial spores at low
p
H was investigated in detail. Unlike activation of spores in distilled water at a neutral
p
H, activation at low
p
H involves two superimposed processes: enhanced activation and death. Low-
p
H-activated spores failed to germinate in
d
-alanine, in contrast to spores activated at neutral
p
H, owing to the abolition of alanine-racemase activity. Morphological and permeability changes such as release and partial disruption of spores were dipicolinic acid-observed during low-
p
H activation. The kinetics pattern of low-
p
H activation, as well as the change in properties of the spores thereafter, suggest that the mechanism of low-
p
H activation differs from that of other kinds of heat-activation.
Characterization of Injury Incurred by
Escherichia coli
upon Freeze-Drying
Authors: Sinskey T. J. , Silverman G. J.
Published: January 2020

When cells of
Escherichia coli
ML30 were suspended in 2% gelatin and frozen at −40 C, no appreciable metabolic damage or death occurred. After freeze-drying for 8 hr at a platen temperature of 49 C and rehydration with a mineral salts medium, survival of the cells was 0.6%. Metabolic damage of the survivors was found to be 23%. Permeability alterations were detected by several criteria. Freeze-dried cells were susceptible to antibiotics normally ineffective against
E. coli
and leakage of ribonucleic acid (RNA) occurred. Analysis of ribosomal extracts of rehydrated freeze-dried cells demonstrated the presence of appreciable degradation products. Permeability alterations were shown to be reversible by the observation that antibiotic susceptibility was a time-dependent process and that the gratuitous inducer of β-galactosidase was not concentrated by freeze-dried cells until the injured cells had been incubated in a nutrient medium for 300 min or more. At approximately the same time, metabolic damage was repaired. RNA synthesis preceded protein synthesis by about 150 min, and deoxyribonucleic acid synthesis occurred with the resumption of normal growth. This was interpreted to be the result of repair of RNA taking place before protein synthesis and growth could resume. A pronounced increase in the lag time of freeze-dried cells was also observed. Peptides and Casamino Acids shortened the lag time for freeze-dried cells but not for the controls. Glycerol and glucose were found to be better carbon sources for growth of freeze-dried cells than sodium lactate or sodium succinate.
Regulation of Enzymes Involved in the Conversion of Tryptophan to Nicotinamide Adenine Dinucleotide in a Colorless Strain of
Xanthomonas pruni
Authors: Brown Albert T. , Wagner Conrad
Published: January 2020

A colorless strain of
Xanthomonas pruni
was isolated which is capable of converting tryptophan to nicotinamide adenine dinucleotide (NAD). The enzymes responsible for the conversion of tryptophan to quinolinic acid were shown to be present. Nicotinic acid-requiring mutants were isolated, and it was found that the growth of these mutants can be supported by various intermediates on the pathway from tryptophan to NAD. The first three enzymes on this pathway are induced coordinately by
l
-tryptophan. Gratuitous inducers of these enzymes include
d
-tryptophan, α-methyl-
dl
-tryptophan, and 4-methyl-
dl
-tryptophan; formyl-
l
-kynurenine and
l
-kynurenine were not effective as inducers. These data suggest that at least the first three enzymes in the pathway from tryptophan to NAD are under common regulatory control.
Regulation of Ribosomal Protein Synthesis in
Escherichia coli
Authors: Harvey R. J.
Published: January 2020

The kinetics of synthesis of ribosomal, nonribosomal, and total protein, and of ribosomal ribonucleic acid (RNA), were measured in
Escherichia coli
during a shift-up involving a doubling of specific growth rate. The increase in ribosomal protein synthesis was not accompanied by a corresponding decrease in non-ribosomal protein synthesis. Thus, the average rate of protein synthesis per ribosome increased after the shift. The increase did not occur by an increase in polypeptide chain growth rates. The average growth periods of ribosomal and nonribosomal proteins did not change after a shift, and were constant in cells in balanced growth over a wide range of specific growth rates. The average growth period for ribosomal protein was twice that for nonribosomal protein. The fraction of ribosomes in polyribosomes was found to increase after the shift, accounting for the increase in ribosomal protein synthesis and in protein synthesis per ribosome. These results show that ribosomal protein synthesis is regulated by control of initiation of either transcription or translation of ribosomal protein messenger RNA, by some means other than availability of free ribosomes. If the messenger for ribosomal protein is ribosomal RNA, the conclusions can be extended to apply to regulation of ribosomal RNA synthesis. In support of this, it is shown that ribosomal RNA and ribosomal protein synthesis are closely coordinated during a shift.
Genetic Analysis in
Bacillus pumilus
by PBS1-Mediated Transduction
Authors: Lovett Paul S. , Young Frank E.
Published: January 2020

Bacteriophage PBS1 mediates generalized transduction in
Bacillus pumilus
NRRL B-3275 (BpB1). Transduction frequencies for single auxotrophic markers are of the order of 10
−4
transductants per plaque-forming unit in crude phage lysates. The characteristics of PBS1 propagated on BpB1 and the properties of the system of transduction are similar to those reported for PBS1 propagated on
Bacillus subtilis
. By transduction, eight amino acid auxotrophic markers in BpB1 have been oriented into two linkage groups. One group contains the auxotrophic markers arginine A, leucine, and phenylalanine, and the other group contains the markers lysine, serine, tryptophan, isoleucine-valine, and isoleucine. The nature and relative order of the markers within each linkage group suggest that the arrangement of genes in these areas of the chromosome of BpB1 is similar to the arrangement of phenotypically comparable genes in two linkage groups (defined by PBS1 transduction) in
B. subtilis
. However, transduction of any of the above cited markers in BpB1 to prototrophy with PBS1 propagated on
B. subtilis
168 could not be demonstrated. In addition to BpB1, seven other strains of
B. pumilus
can be infected with PBS1. Transduction has been demonstrated in three of these strains.
Ultraviolet-Induced Reversions of
Salmonella his
Frameshift Mutations
Authors: Kanazir Dusan T. , Hartman Philip E. , Savic Dragutin
Published: January 2020

Ultraviolet (UV) light elicits reversions in 12
his
frameshifts that also revert in response to ICR191. Reversion also is stimulated by UV in two of four spontaneously revertible, but ICR-negative, frameshifts.
Cell Wall Glucans of the Yeast and Mycelial Forms of
Paracoccidioides brasiliensis
Authors: Kanetsuna Fuminori , Carbonell Luis M.
Published: January 2020

Glucans were isolated from the cell wall of the yeast (Y) and mycelial (M) forms of
Paracoccidioides brasiliensis
. The alkali-soluble glucan of the Y form had properties of α-1,3-glucan. The alkali-insoluble glucan of the M form was identified as a β-glucan which contains a β-(1 → 3)-glycosidic linkage by infrared absorption spectrum, by effect of β-1,3-glucanase, and by partial acid hydrolysis. The alkali-soluble glucans of the M form were a mixture of α- and β-glucans and the ratio of α- to β-glucan was variable, depending on the preparations.
Purification of a
d
-Mannose Isomerase from
Mycobacterium smegmatis
Authors: Hey-Ferguson Ann , Elbein Alan D.
Published: January 2020

An enzyme,
d
-mannose ketol isomerase, catalyzing the isomerization of
d
-mannose and
d
-fructose was purified approximately 60-fold from cells of
Mycobacterium smegmatis
grown on mannose as the sole carbon source. This enzyme was shown to catalyze the conversion of
d
-mannose and
d
-lyxose to ketoses. The ketose produced from mannose was identified as fructose by chemical and chromatographic methods. The reaction was shown to be reversible, the equilibrium ratio of fructose to mannose being approximately 65 to 35. The
p
H optimum was about 7.5, and the
K
m
for mannose was estimated to be 7 × 10
−3
m
. Mannose isomerase activity was greatest in cells grown on mannose, whereas cells grown on fructose had about 30% as much activity. Very low levels of activity were detected in cells grown on other substrates. There was an immediate increase in enzyme activity on transfer of cells from nutrient broth to a mannose mineral salts medium.
Correlation Between Reduced Nicotinamide Adenine Dinucleotide Phosphate Levels and Morphological Changes in
Neurospora crassa
Authors: Brody Stuart
Published: January 2020

A colonial mutant of
Neurospora crassa
, previously shown to be altered in the structure of glucose-6-P dehydrogenase [a reduced nicotinamide adenine dinucleotide phosphate (NADPH) producing reaction], contained only 40% as much NADPH in extracts as did the wild type. A partial revertant strain, when grown at 23 C, had the same total NADPH content as the wild type, but, at 34 C, had lower levels of NADPH as well as a colonial morphology. A revertant with complete wild-type morphology had wild-type levels of NADPH. Two different colonial mutants, which have also been reported to be altered in NADPH-generating reactions, were found to have a lower content of NADPH, whereas other colonial mutants had wild-type levels. The wild-type strain, when grown under conditions in which it contained a lower total content of NADPH, had a morphology similar to that of a colonial mutant. The evidence indicates that lowered NADPH content leads to a dramatic alteration in the morphology of
Neurospora
, but not necessarily vice versa. The possible pleiotropic effects of the NADPH deficiency are discussed.