bluuebunny/crossref_metadata_2025 huggingface dataset:
Penicillin and Cell Wall Synthesis: a Study of
Bacillus licheniformis
by Electron Microscopy
Authors: Highton Peter J. , Hobbs D. G.
Published: January 2020

The changes in wall structure of two penicillinase-negative strains of
Bacillus licheniformis
on addition of penicillin were studied. After addition of penicillin to give a concentration of 1 unit/ml, exponentially growing cells of strain 749 c/72 doubled once and then stopped. Strain 749c/72/IIIg was more resistant and continued growing, but synthesis appeared to become uncontrolled over the surface, producing localized wall thickening at the expense of elongation, and leading to distorted cells and growth in twisted and coiled chains, with an accompanying drop in growth rate. The continued growth can be explained by the existence of a less sensitive transpeptidase, but there is no obvious explanation for the uncontrolled synthesis. The effect of penicillin could be reversed by addition of penicillinase in both strains, although there appeared to be a persistent effect of penicillin which also produced distorted cells for a few generations and inhibited cell separation. The changes in wall structure produced by penicillin and penicillinase appeared all over the cell surface, suggesting that wall synthesis occurred all over the cell. Also a separate process for cross-wall synthesis is suggested since this appeared less sensitive than wall synthesis.
New Structures in the Basidiomycete,Coniophora cerebella
Authors: Langvad Finn
Published: January 2020

Previously undescribed structures found inConiophora cerebellaare described. They appear like spherical bodies, about 0.5 μm in diameter, situated along the wall and septa of the hyphae. They are not membrane bound and seem to be composed of ribosomes.
Morphology and Ultrastructure ofMycoplasma pneumoniaeSpherules
Authors: Boatman Edwin S. , Kenny George E.
Published: January 2020

During growth in fluid medium, most strains ofMycoplasma pneumoniaeproduce free-floating granules which become larger with time. We have called these granules “spherules.” This study describes the morphological and ultrastructural features ofM. pneumoniaestrain AP-164 spherules, both free and in association with HeLa cells in cell culture. In thin section, spherules were composed of lobulated cells, connected together by membranes, and ring-shaped cells. The two-dimensional morphology observed varied according to the plane of section and to the age of the culture. In HeLa cell cultures, mycoplasmata were found attached to plasma membranes of cells; in sections, individual mycoplasmata were often aligned in radial apposition to the membranes. Mycoplasmata were not found intracellularly. The three-dimensional morphology of spherules was examined by the critical point method and by scanning electron microscopy. Both methods revealed lobulated forms, ring-shaped forms, and star-shaped forms. Treatment of the spherules with crude porcine pancreatic lipase effectively released large numbers of free organisms. Phosphotungstic acid preparations of these uncentrifuged forms revealed a morphology in agreement with the other methods used. Lobulated ring forms with “beaded” filaments were prominent. In respect to morphology,M. pneumoniaeunder our conditions resembles that of the type speciesM. mycoides.
Differences Between
Escherichia coli
B/r and
Salmonella typhimurium
LT-2 in the Sedimentation Behavior of the Deoxyribonucleic Acid Synthesized After X-Irradiation
Authors: Hudnik-Plevnik Tamara A. , Djordjević Nadežda
Published: January 2020

After irradiation, nearly equal amounts of deoxyribonucleic acid (DNA) are synthesized in radiation-sensitive
Salmonella typhimurium
and in resistant
Escherichia coli
B/r. However, the DNA synthesized in
S. typhimurium
is of low molecular weight, whereas that made in the
E. coli
B/r is like that synthesized in the unirradiated controls.
Attempts to Detect an Alternative Vital Role for the Reduced Nicotinamide Adenine Dinucleotide Phosphate-Nitrate Reductase Structural Gene in
Aspergillus nidulans
Authors: Downey R. J. , Cove D. J.
Published: January 2020

A possible alternate vital role of the structural gene for reduced nicotinamide adenine dinucleotide phosphate-nitrate reductase in
Aspergillus nidulans
was tested for and found to be absent in a significant number of haploid and diploid strains.
Induction of Colicin la at High Temperature
Authors: Gromkova Rosa H.
Published: January 2020

Induction of colicin la at a high temperature (42 C) was demonstrated in a wild strain of
Shigella sonnei
. After transfer of the Col factor, a similar effect was observed in those recipient cells acquiring colicinogeny. The induction is suggested to be due to the presence of a thermosensitive colicin repressor. The wild-type strain segregated sensitive cells and showed heterogeneity in colicin production.
Isolation of Vitamin B
12
Transport Mutants of
Escherichia coli
Authors: Di Girolamo Paula M. , Kadner Robert J. , Bradbeer Clive
Published: January 2020

Escherichia coli
KBT001, a methionine-vitamin B
12
auxotroph, was found to require a minimum of 20 molecules of vitamin B
12
(CN-B
12
) per cell for aerobic growth in the absence of methionine. After mutagenesis with
N
-methyl-
N
′-nitro-
N
-nitrosoguanidine and penicillin selection, two kinds of B
12
transport mutant were isolated from this strain. Mutants of class I, such as KBT069, were defective in the initial rapid binding of CN-B
12
to the cell and were unable to grow in the absence of methionine even with CN-B
12
concentrations as high as 100 ng/ml. The class II mutants possessed intact initial phases of CN-B
12
uptake but were defective in the secondary energy-dependent phase. These strains were also unable to convert the CN-B
12
taken up into other cobalamins. In the absence of methionine, some of these strains (e.g., KBT103) were able to grow on media containing 1 ng of CN-B
12
/ml, whereas others (e.g., KBT041) were unable to grow with any of the CN-B
12
concentrations used. Osmotic shock treatment did not affect the initial rate of uptake of CN-B
12
but gave a substantial decrease in the secondary rate. Trace amounts of B
12
-binding macromolecules were released from the cells by the osmotic shock, but only from strains such as KBT001 and KBT041 which possessed an active initial phase of CN-B
12
uptake. These results are interpreted as being consistent with the view that the initial CN-B
12
binding site which functions in this transport system is probably bound to the cell membrane.
Effect of Serine Hydroxamate on the Growth of
Escherichia coli
Authors: Tosa Tetsuya , Pizer Lewis I.
Published: January 2020

The structural analogue of
l
-serine,
l
-serine hydroxamate, inhibited the growth of
Escherichia coli
K-12. Of the other amino acid hydroxamates tested, only
l
-lysine hydroxamate reduced the rate of growth. Inhibition of growth by
l
-serine hydroxamate was rapidly reversed by the addition of
l
-serine to the bacterial culture or by removal of the analogue by filtration. The reversal of inhibition was specific for
l
-serine.
l
-Alanine, glycine, or adenine had no effect on an inhibited culture. No evidence for active transport of the analogue was obtained.
Fatty Acid and Sterol Composition of
Mucor genevensis
in Relation to Dimorphism and Anaerobic Growth
Authors: Gordon P. A. , Stewart P. R. , Clark-Walker G. D.
Published: January 2020

Fatty acid and sterol content and composition were determined for the dimorphic mold,
Mucor genevensis
, grown under a variety of experimental conditions. Fatty acids account for 6 to 9% of the dry weight of aerobically grown mycelium, and 70 to 80% of these are unsaturated. The organism contains γ-linolenic acid which is characteristic for
Phycomycetes
, and in sporangiospores this compound represents 40% of the total fatty acids. Of the sterols found in mycelium, 80% is ergosterol, and stigmasterol was positively identified as one of the minor components. In anaerobically grown yeastlike cells, sterol content is less than 10% of the level found in aerobically grown cells, and fatty acids amount to less than 2% of the dry weight. These fatty acids are predominantly short chain and less than 10% are unsaturated. Yeastlike cells obtained under aerobic conditions by growth in the presence of phenethyl alcohol have fatty acid and sterol compositions characteristic of aerobically grown mycelium. It is concluded that the dimorphology of the organism is not directly related to lipid composition.
Hyperinducibility as a Result of Mutation in Structural Genes and Self-Catabolite Repression in the
ara
Operon
Authors: Katz Leonard , Englesberg Ellis
Published: January 2020

Mutations in gene
araB
producing an
l
-arabinose-negative phenotype cause either an increase (hyperinducible), decrease (polar), or have no effect at all on the inducible rate of expression of the
l
-arabinose operon. Fourteen
araB
gene mutants exhibiting such effects were shown to be the result of: nonsense, frameshift, or missense mutations. All missense mutants were hyperinducible, exhibiting approximately a twofold increase in rate of
l
-arabinose isomerase production. All frameshift and most nonsense mutants exhibited polar effect. One nonsense mutant was hyperinducible. The
cis
-dominant polar effect of nonsense and frameshift mutants (as compared to induced wild type) were more pronounced in arabinose-utilizing merodiploids and in

araBaraC
c

double mutants where inducible and constitutive enzyme levels are respectively determined. On the other hand, in arabinose-utilizing merodiploids, missense mutations no longer exhibited hyperinducibility but displayed a wild-type level of operon expression. Increases in the wild type-inducible rate of expression of the operon were found when growth rate was dependent on the concentration of
l
-arabinose. Cyclic 3′,5′-adenosine monophosphate also stimulated expression of the operon with the wild type in a mineral
l
-arabinose medium. These observations are explained on the basis that the steady-state expression of the
l
-arabinose operon
OIBAD
is dependent on the concentration of (i)
l
-arabinose, the effector of this system, which stimulates the expression of the operon, and (ii) catabolite repressors, produced from
l
-arabinose, which dampen the expression of the operon. We have termed the latter phenomenon “self-catabolite” repression.
Mutants of
Escherichia coli
Lacking Endonuclease I, Ribonuclease I, or Ribonuclease II
Authors: Wright Michel
Published: January 2020

To isolate mutants of
Escherichia coli
K-12 lacking endonuclease I activity (
end
), a method has been developed which detects, by differential methyl green staining, undegraded deoxyribonucleic acid (DNA) in colonies previously incubated in toluene. This procedure allows isolation of mutant strains in which DNA degradation is reduced. For half of these strains, this defect has been correlated with deficiencies of endonuclease I, ribonuclease I (
rns
), or ribonuclease II (
rne
) activities. The enzymatic deficiencies of the other strains remain unknown. An
rne
mutation is cotransducible with
serA
(which is located at 56 min on the genetic map). Most
end
mutations, called
endA
, are also cotransducible with
serA
and are located between
serA
and
strA
. One
end
mutation, called
endB
, is located between
purE
and
trp
(i.e., between 13 and 25 min on the genetic map).
Chromosome Replication and the Division Cycle of
Escherichia coli
B/r
Authors: Kubitschek H. E. , Freedman M. L.
Published: January 2020

The average amount of deoxyribonucleic acid (DNA) per cell was measured in steady-state cultures of
Escherichia coli
B/r grown at 37 C in glucose-limited chemostats or in batch cultures in the exponential growth phase as maintained with one of several carbon sources. Within experimental errors, DNA content was dependent only on growth rate and independent of the type of culture, the carbon source, or the addition of growth factors. The amount of DNA per cell increased continuously with growth rate over the range of 0.02 to 3 divisions per hour. The data over the entire range of growth rates are in agreement with a constant time for a single replication point to traverse the entire genome, 47 min, and with cell division following 25 min after termination of replication. The measured amount of DNA per genome was 4.2 × 10
−15
g (or 2.5 × 10
9
daltons).
Inactivation of 1,6-Diphosphatase by Glucose in Yeast
Authors: Gancedo Carlos
Published: January 2020

Fructose-1,6-diphosphatase was derepressed in
Saccharomyces cerevisiae
by incubation in media containing non-sugar carbon sources. Addition of glucose to a derepressed culture led to a rapid loss of the measurable activity of the enzyme. Fructose and mannose also produced inactivation, but 2-deoxyglucose was ineffective. Experiments with cycloheximide indicated that the inactivation does not require protein synthesis. It was also shown that the process is not energy-dependent. The reappearance of the enzyme was dependent on an energy source and was prevented by cycloheximide. These results suggest that fructose diphosphatase inactivation is irreversible and that reappearance of enzyme activity implies de novo synthesis. Screening of different genera of yeasts has shown that the inactivation of fructose diphosphatase is a relatively widespread phenomenon.
Ampicillin-Resistant Mutants ofEscherichia coliK-12 with Lipopolysaccharide Alterations Affecting Mating Ability and Susceptibility to Sex-Specific Bacteriophages
Authors: Monner David A. , Jonsson Staffan , Boman Hans G.
Published: January 2020

Mutations from moderate (class I) to high (class III) ampicillin resistance in a male and a female strain ofEscherichia coliK-12 have been found to be accompanied by surface alterations, first demonstrated as hindrance in the formation of mating pairs. These changes have now been studied with the ribonucleic acid phage MS2, and especially with the “female-specific” phage φW. Several class III mutations in male and female strains were found to make the cells susceptible to phage φW and to reduce their abilities to form mating pairs. Spontaneous phage φW-resistant mutants isolated from class III strains were found also to have acquired changes in ampicillin resistance and ability to form mating pairs. One mutant had reverted to parental class I type in all three properties. Lipopolysaccharides (LPS) prepared from φW-sensitive class III strains inactivated the phage in vitro, whereas LPS from phage-resistant strains had no effect. Carbohydrate analyses of LPS preparations showed that two class III mutants, compared to their parental strains, had lost significant parts of the rhamnose, galactose, and glucose from the LPS. One of the phage φW-resistant mutants showed a partial restoration of its carbohydrate composition. Other φW-resistant mutants showed, instead, further losses of carbohydrates in their LPS. It is suggested that genes exist which simultaneously mediate a female-specific mating site, ampicillin resistance, and the receptors for phage φW.
Effect of Pleiotropic Carbohydrate Mutations (
ctr
) on Tryptophan Catabolism
Authors: Dahl Rolf , Wang Richard J. , Morse M. L.
Published: January 2020

The pleiotropic
ctr
mutation has been shown to affect tryptophan uptake and tryptophanase formation. Genetic reversions are of two types: (i) complete, restoring to wild type, located at 46 to 47 min; (ii) partial, restoring only tryptophanase synthesis, located at 73 min. In some strains the effect of
ctr
mutations could be reversed by cyclic adenosine 3′,5′-monophosphate (cAMP) plus tryptophan. A mutant producing tryptophanase constitutively was suppressed by a
ctr
mutation. Production of tryptophanase in this suppressed strain was not restored by the addition of cAMP, but required cAMP plus tryptophan.
Enriched Selection of Dominant Mutations: Histidine Operator Mutations
Authors: Chang George W. , Straus Daniel , Ames Bruce N.
Published: January 2020

In the course of selection of bacteria with derepressed levels of histidine biosynthetic enzymes, it was found that when mutagen-treated cells were spread on a selective medium without allowing intervening growth to occur, the frequency of operator mutants obtained was dramatically increased. This may be useful as a general enrichment for operator or other dominant mutations.
Observations on Replication and Cell Division in Synchronous Cultures of the Blue-Green Alga
Anacystis nidulans
Authors: Herdman M. , Carr N. G.
Published: January 2020

A second synchrony induction treatment, half-way through the deoxyribonucleic acid replication process of an already synchronized culture, resulted in defective subsequent cell growth. This supports a previous explanation for the partial loss of viability after synchrony induction.
Some Effects of Temperature on the Growth of F Pili
Authors: Novotny Charles P. , Lavin Karen
Published: January 2020

The effect of temperature on the production of F pili by an F
+
strain of
Escherichia coli
B/r was studied by electron microscopy and by a technique involving serum-blocking power. The latter method is based on the ability of F pili to adsorb F pili antibody which inhibits male-specific phage infection. The total amount of pili in a sample was estimated by serum-blocking power; the length of F pili and number per cell was determined by electron microscopy. Cell extracts prepared by sonic oscillation lacked serum-blocking power, suggesting that F pili are not present in the cytoplasm. The number of F pili per cell varied with the growth temperature, but the average length of F pili remained constant. Maximum number of pili per cell occurs between 37 and 42 C; below 37 C the number decreases, reaching zero at about 25 C. When cells are grown at 37 C, blended, and resuspended in fresh media at 25 C, they make F pili. These pili are probably assembled from a pool of subunits that were synthesized during growth at 37 C. The rates of assembly at 25 and 37 C, as judged by the rate of increase in length of F pili, are similar. When cells were grown at 25 C and shifted up to 37 C, there was a 30-min lag in pili production followed by a period of rapid outgrowth. When cells were shifted down from 37 to 20 C, outgrowth (assembly) of pili ceased, and approximately 50% of the attached pili were released in 2 min. No release was observed when cells were shifted to 0 C. This suggests that pili may be released from the cell by a mechanism that requires metabolic activity, but not the outgrowth of F pili.
Selective Inhibition of Enzyme Synthesis Under Conditions of Respiratory Inhibition
Authors: Flavell Richard B. , Woodward Dow O.
Published: January 2020

When
Neurospora
mycelium is transferred from a medium containing sucrose to one containing acetate as sole source of carbon, a preferential synthesis of many Krebs cycle, glyoxylate cycle, and associated enzymes occurs. Respiration was inhibited during preferential enzyme synthesis in the following ways. (i) The amount of aeration (shaking) was reduced, (ii) cyanide was added to the culture, (iii) the carbon source, acetate, was removed, (iv) a mutant strain was starved of its Krebs cycle intermediates, and (v) respiration was inhibited by mutation. The effect of this respiratory inhibition on the synthesis of a number of enzymes was measured. It was found that the synthesis of nicotinamide adenine dinucleotide (NAD)-linked glutamate dehydrogenase and phosphoenolpyruvate carboxykinase was significantly less inhibited under conditions of respiratory inhibition than was the synthesis of Krebs cycle, glyoxylate cycle, and most other cell proteins synthesized during the adaptation period. This differential inhibition of enzyme synthesis was almost certainly
not
due to differential repression by regulatory metabolic end product effectors. Inhibition of mitochondrial respiration under these conditions most likely results in a limitation of the energy supply of the cell. Thus, it is suggested that the inhibition of synthesis of most proteins after inhibition of mitochondrial respiration results from a lack of energy in a utilizable form. Possible reasons to account for the relative insensitivity of NAD-linked glutamate dehydrogenase and phosphoenolpyruvate carboxykinase to inhibition under these conditions are discussed.
Formation of β-Cyanoalanine by
O
-Acetylserine Sulfhydrylase
Authors: Castric Peter A. , Conn Eric E.
Published: January 2020

Cell-free extracts of
Bacillus megaterium
form β-cyanoalanine (β-CNA)-
14
C from Na
14
CN and
l
-cysteine,
O
-acetyl-
l
-serine or, to a lesser extent,
l
-serine. However, the presence of cyanide in the growth medium does not increase the capacity of cell extracts to catalyze the formation of β-CNA from cysteine and cyanide. The formation of β-CNA is readily detected in extracts of cells grown in synthetic media with sulfate or
l
-djenkolic acid as sulfur sources; such cells also exhibit an increased ability to form cysteine when compared with cells grown on cysteine as the sulfur source. β-CNA formation could not be detected in extracts of cells grown on cysteine as the sulfur source. A 40-fold purification of the
O
-acetyl-serine sulfhydrylase resulted in the co-purification of the β-CNA-forming activity. The sulfhydrylase and the β-CNA-forming activity co-chromatographed on diethyl-aminoethyl cellulose and Sephadex G-100.
Metabolism of 4-
N
-Hydroxy-Cytidine in
Escherichia coli
Authors: Trimble R. B. , Maley Frank
Published: January 2020

4-
N
-hydroxy-cytidine was found to substitute for uridine as a pyrimidine supplement for the growth of
Escherichia coli
Bu
−
. Measurement of the incorporation of 4-
N
-hydroxy-cytidine-
2
-
14
C
into ribonucleic acid and deoxyribonucleic acid revealed that this compound was converted to cytidine or uridine before utilization. Two pathways for metabolism were considered: (i) the reduction of 4-
N
-hydroxy-cytidine to cytidine followed by deamination, (ii) the direct hydrolysis of hydroxylamine from 4-
N
-hydroxy-cytidine to yield uridine. A threefold increase in cytidine (deoxycytidine) deaminase (EC 3.5.4.5) activity, when the cells were grown on 4-
N
-hydroxy-cytidine, suggested the involvement of this enzyme. More direct proof was obtained by purifying the deaminase 185-fold and finding that it released hydroxylamine from 4-
N
-hydroxy-cytidine at one-fiftieth the rate at which ammonia was removed from cytidine. This result is consistent with the slower rate of growth of the Bu
−
cells on 4-
N
-hydroxy-cytidine than cytidine and suggests that the second pathway is the major route for utilization of this compound.
Nicotinamide Deamidation by Microorganisms in Rat Stomach
Authors: Shimoyama Makoto , Tanigawa Yoshinori , Ito Toichi , Murashima Ryuzo , Ueda Iwao , Tomoda Tsunesuke
Published: January 2020

We have extended our investigation of nicotinamide deamidation in the stomach of conventional rats. The bacterial species in the pars preventricularis were identified as
Flavobacterium peregrinum, Escherichia coli, Streptococcus faecalis
, and
Lactobacillus acidophilus
, listed in order of decreasing deamidase activity. Nicotinamide-
7
-
14
C
ingested into rat stomach was rapidly deamidated to nicotinic acid. These results contribute to the accumulated evidence that microorganisms present in the pars preventricularis of rat stomach are responsible for the deamidation of nicotinamide to nicotinic acid, a known precursor of mammalian pyridine nucleotides.
Detection of Relationships BetweenStreptococcus faecalisandLactobacillus caseiby Immunological Studies with Two Forms of Malic Enzyme
Authors: London Jack , Meyer Eleanor Y. , Kulczyk Sandra R.
Published: January 2020

Antisera prepared against two isologous malic enzymes fromLactobacillus caseistrains 64H and M40 were used to survey and categorize the various malic enzymes found within this diverse species. In addition to detecting three major antigenic variants of malic enzyme within this group, both antisera readily reacted withStreptococcus faecalismalic enzyme. The cross-reactions between theL. caseimalic enzyme antisera and theS. faecalismalic enzyme indicated that these iso-functional enzymes found in two apparently diverse groups of organisms were immunologically homologous. A scheme proposing a common ancestry for the two speciesS. faecalisandL. caseibased on the results of quantitative immunological studies is presented.
Antimicrobial Actions of Hexachlorophene: Cytological Manifestations
Authors: Silvernale J. N. , Joswick H. L. , Corner Thomas R. , Gerhardt Philipp
Published: January 2020

Hexachlorophene is a soap-compatible bisphenol that has been widely used as an antiseptic, yet its mechanism of action is undefined. The relative threshold concentration for bactericidal effect on a susceptible test organism,
Bacillus megaterium
, was established to be about 10 μg/mg of cell dry weight. At this or at high (≥100 μg/mg) concentration, adsorptive uptake by cells displayed saturation kinetics. At about 30 μg/mg, the time course of adsorption occurred in three distinct stages. The triphasic pattern was interpreted to represent successive penetration of and adsorption by the cell wall, the protoplast membrane, and the cytoplasm. This interpretation was substantiated by determinations of hexachlorophene adsorption by isolated cell components. Electron microscopy disclosed cytopathology, evidenced as gaps or discontinuities, in the protoplast membrane (but not in the cell wall or cytoplasm) at > 30 μg of hexachlorophene per mg of cell dry weight. Similarly, treatment with > 30 μg/mg allowed a fluorescigenic dye (tolyl-peri acid) to penetrate into the protoplast. However, no detectable cytological manifestations were discerned at the minimum lethal concentration of 10 μg/mg. Apparently, hexachlorophene is physically disruptive at intermediate or high relative concentrations but acts in a more subtle fashion at the minimal lethal concentration.
Antimicrobial Actions of Hexachlorophene: Lysis and Fixation of Bacterial Protoplasts
Authors: Corner Thomas R. , Joswick H. L. , Silvernale J. N. , Gerhardt Philipp
Published: January 2020

Hexachlorophene was found to be both a lytic and a fixative agent for protoplasts isolated from
Bacillus megaterium
. Concentrations of 50 to 100 μg of drug per mg of original cell dry weight were required to lyse 4.4 × 10
9
protoplasts (2 mg of original cell dry weight). At higher drug concentrations, protoplasts became fixed against osmotic stress and reduced in sensitivity to disruption by
n
-butanol. Lower drug concentrations caused proportionate lysis in the protoplast population. Intact cells lost the ability to become plasmolyzed at these same hexachlorophene concentrations. Nonplasmolyzed, drug-treated cells were resistant to the action of lysozyme, whereas plasmolyzed, drug-treated cells were sensitive. But the sensitivity of isolated cell walls to lysozyme digestion was not markedly altered by hexachlorophene treatment. These effects appeared to be secondary in the killing of cells by hexachlorophene because they occurred at concentrations higher than the minimum lethal concentration.
Physical Properties and Mechanism of Transfer of R Factors in
Escherichia coli
Authors: Vapnek Daniel , Lipman Muriel B. , Rupp W. Dean
Published: January 2020

The physical properties of F-like and I-like R factors have been compared with those of the wild-type F factor in
Escherichia coli
K-12 unmated cells and after transfer to recipient cells by conjugation. The F-like R factor R538-1
drd
was found to have a molecular weight of 49 × 10
6
, whereas the molecular weight of the I-like R factor R64
drd
11 was 76 × 10
6
. The wild-type F factor, F1, had a molecular weight of 62 × 10
6
. When conjugation experiments are performed by using donor strains carrying these derepressed F-like or I-like R factors, the transferred deoxyribonucleic acid can be isolated as a covalently closed circle from the recipient cells. This circular deoxyribonucleic acid was characterized by making use of the observation that the complementary strands of these R factors can be separated in a CsCl-poly (U, G) equilibrium gradient. The results of the strand-separation experiments show that only one of the complementary strands of the R factor is transferred from the donor to the recipient. With both the F-like and I-like R factors, this strand is the heavier strand in CsCl-poly (U, G). These results indicate that even though F-like and I-like R factors differ greatly in many properties (phage specificity, size, compatability, etc.), they are transferred by a similar mechanism.
Genetic Evidence for Subunits in the Fertility Repressor Produced by F-Like R Factors
Authors: Hoar David I.
Published: January 2020

Repressor-negative mutants derived from R 100 were tested for genetic complementation. The results indicate that the active repressor is a multimer. The properties of an unusual repressor mutant are also discussed.
Chemotactic Response to Amino Acids by
Pseudomonas aeruginosa
in a Semisolid Nitrate Medium
Authors: Hamilton P. B. , Shelley Gail
Published: January 2020

Pseudomonas aeruginosa
exhibited positive chemotaxis to glutamate, alanine, and arginine in a nutrient semisolid nitrate medium.
Changes in Terminal Respiratory Pathways of
Bacillus subtilis
During Germination, Outgrowth, and Vegetative Growth
Authors: Tochikubo Kunio
Published: January 2020

The chemical and enzymatic properties of the cytochrome system in the particulate preparations obtained from dormant spores, germinated spores, young vegetative cells, and vegetative cells of
Bacillus subtilis
PCI219 were investigated. Difference spectra of particulate fractions from dormant spores of this strain suggested the presence of cytochromes
a, a
3
,
b, c
(+
c
1
), and
o
. All of the cytochrome components were present in dormant spores and in germinated spores and vegetative cells at all stages which were investigated. Concentrations of cytochromes
a, a
3
,
b
, and
c
(+
c
1
) increased during germination, outgrowth, and vegetative growth, but that of cytochrome
o
was highest in dormant spores. As the cytochrome components were reducible by reduced nicotinamide adenine dinucleotide (NADH), they were believed to be metabolically active. Difference spectra of whole-cell suspensions of dormant spores and vegetative cells were coincident with those of the particulate fractions. NADH oxidase and cytochrome
c
oxidase were present in dormant spores, germinated spores, and vegetative cells at all stages after germination, but succinate cytochrome
c
reductase was not present in dormant spores. Cytochrome
c
oxidase and succinate cytochrome
c
reductase activities increased with growth, but NADH oxidase activity was highest in germinated spores and lowest in vegetative cells. There was no striking difference between the effects of respiratory inhibitors on NADH oxidase in dormant spores and those on NADH oxidase in vegetative cells.
Binding of Radioactive Benzylpenicillin to Sporulating
Bacillus
Cultures: Chemistry and Fluctuations in Specific Binding Capacity
Authors: Lawrence Paul J. , Rogolsky Marvin , Hanh Vo Thi
Published: January 2020

The chemistry of the binding of
14
C-benzylpenicillin to sporulating cultures of
Bacillus megaterium
and
B. subtilis
is similar to that in a 4-hr vegetative culture of
Staphylococcus aureus
. Unlabeled penicillins prevent the binding of
14
C-benzylpenicillin, but benzylpenicilloic acid and benzylpenilloic acid do not. Bound antibiotic can be removed from cells with neutral hydroxylamine at 25 C. Sporulating cultures display two intervals of enhanced binding, whereas binding to stationaryphase
S. aureus
cells remains constant. The first period of increased binding activity occurs during formation of the spore septum or cell wall primordium development, and the second coincides with cortex biosynthesis.
Effects of Hydrostatic Pressure and Temperature on the Uptake and Respiration of Amino Acids by a Facultatively Psychrophilic Marine Bacterium
Authors: Paul Kala L. , Morita Richard Y.
Published: January 2020

Studies of pressure and temperature effects on glutamic acid transport and utilization indicated that hydrostatic pressure and low temperature inhibit glutamate transport more than glutamate respiration. The effects of pressure on transport were reduced at temperatures near the optimum. Similar results were obtained for glycine, phenylalanine, and proline. Pressure effects on the transport systems of all four amino acids were reversible to some degree. Both proline and glutamic acid were able to protect their transport proteins against pressure damage. The data presented indicate that the uptake of amino acids by cells under pressure is inhibited, which is the cause of their inability to grow under pressure.
Distribution of the Sites of Alkaline Phosphatase(s) Activity in Vegetative Cells of
Bacillus subtilis
Authors: Ghosh B. K. , Wouters J. T. M. , Lampen J. O.
Published: January 2020

Sites of alkaline phosphatase activity have been located by an electron microscopic histochemical (Gomori) technique in vegetative cells of a repressible strain SB15 of
Bacillus subtilis
, derepressed and repressed by inorganic phosphate, and in a mutant SB1004 which forms alkaline phosphatase in a medium high in phosphate. The sites of enzyme activity were revealed as discrete, dense, and largely spherical bodies of varying sizes (20 to 150 nm). Cells of both repressible and repression-resistant strains acted on a wide variety of phosphate esters (
p
-nitrophenylphosphate, β-glycerophosphate, adenosine-5′-phosphate, glucose-6-phosphate, glucose-l-phosphate, adenosine triphosphate, and sodium pyrophosphate) to produce inorganic phosphorus under conditions of alkaline phosphatase assay [0.05
m
tris(hydroxymethyl)aminomethane buffer (
p
H 8.4) containing 2 m
m
MgCl
2
]. The purified alkaline phosphatase also acted on all these esters, although much less effectively on adenosine triphosphate and sodium pyrophosphate than did the cells. Comparison of the relative utilization of the various substrates by repressed and derepressed cells and purified enzyme suggested the presence of multiple enzymes in the cells. Thus, the cytochemical method of trapping the newly generated inorganic phosphorus determines the location of an alkaline phosphatase of broad substrate profile, and in addition locates the sites of other enzymes generating inorganic phosphorus under identical conditions of assay. It is intriguing that all of these enzymes usually exist in a few clusters attached to the peripheral plasma membrane. In addition to this predominant location, there were a few sites of enzyme activity in the cytoplasm unattached to any discernible structure, and also in the cell wall of the repression-resistant and of the derepressed, repressible strains.
Antibacterial Nitroacridine, Nitroakridin 3582: Binding to Nucleic Acids In Vitro and Effects on Selected Cell-Free Model Systems of Macromolecular Biosynthesis
Authors: Wolfe Alan D. , Cook Thomas M. , Hahn Fred E.
Published: January 2020

Nitroakridin 3582 (NA) formed complexes with native deoxyribonucleic acid (DNA) and with transfer ribonucleic acid (tRNA) species from
Escherichia coli
. Spectrophotometric titrations of NA with these nucleic acids produced numerical results from which nonlinear adsorption isotherms were derived. These curves indicated the existence of more than one class of binding sites on the polymers to which NA was bound by more than one process. The stoichiometry of strong binding of NA to double helical DNA was in agreement with a conventional value (1 ligand molecule per 4.2 component nucleotides) for complete intercalation binding. NA inhibited the DNA-dependent DNA polymerase I and RNA polymerase reactions, the first strongly and the second appreciably. These inhibitions corresponded to the extents to which NA inhibits DNA and RNA biosyntheses in vivo. Evidently, NA interferes with the template function of DNA. The drug also inhibited the polymerization of phenylalanine in a cell-free
E. coli
ribosome-polyuridylic acid [poly (U)] system. The effect paralleled an inhibition of the poly (U)-directed binding of phenylalanyl tRNA to ribosomes. Ethidium bromide acted similarly. The antimalarial drug, chloroquine, stimulated polyphenylalanine synthesis, apparently as a result of stimulating the poly (U)-directed binding of phenylalanyl tRNA to ribosomes.
Use of Yeast Populations Fractionated by Zonal Centrifugation to Study the Cell Cycle
Authors: Sebastian J. , Carter B. L. A. , Halvorson H. O.
Published: January 2020

Zonal centrifugation in a sucrose density gradient was used to separate yeast cells primarily by size and thus by age in the cell cycle. This approach provides an alternative to synchronous growth for examining the properties of cells at different stages in the cell cycle.
Fertility of
Salmonella typhimurium
Crosses with
Escherichia coli
Authors: Mojica-A T. , Middleton R. B.
Published: January 2020

At least one factor that causes low fertility of
Salmonella typhimurium
LT2 strains in crosses with
Escherichia coli
K-12 Hfr's can be inhibited by growing the female strains in supplemented minimal salts medium rather than in nutrient broth and by incubating the female strains at 50 C immediately before mating with the Hfr. These pretreatments can enhance the recovery of prototrophic recombinants for markers injected early by the Hfr by a factor of as much as 10
4
. The heat treatment is effective only on the female in intergeneric crosses and gradually loses (within 50 min) its effectiveness after return of heat-treated cells to 37 C. It is concluded that the restriction system of the female is heat-sensitive. Since markers injected late by the male enter females in which the heat-impaired restriction system has recovered, few recombinants for late markers are found. The presence of the leading end of an
E. coli
Hfr in an
S. typhimurium-E. coli
hybrid enhances by up to sevenfold the frequency of
lac
+
recombinants in subsequent crosses with an
E. coli
Hfr if the
E. coli
segment is integrated into the chromosome of the hybrid; the effect is less marked if the
E. coli
segment is not integrated.
Methionineless Death in
Escherichia coli
Authors: Breitman T. R. , Finkleman A. , Rabinovitz M.
Published: January 2020

Methionine auxotrophs of strains derived from
Escherichia coli
15 lose their colony-forming ability when deprived of this amino acid. Late addition of methionine to liquid cultures did not restore plating efficiency but permitted growth of surviving cells. This phenomenon, termed methionineless death (
mld
), was not observed with methionine auxotrophs of
E. coli
strains B, W, or K
12
, nor was a similar amino acidless death observed with corresponding auxotrophs of
E. coli
15 for arginine, tryptophan, proline, isoleucine, and leucine.
Mld
was not dependent upon the genetic site determining methionine auxotrophy, nor did it affect the decarboxylation of methionine or the stability of methionyl-transfer ribonucleic acid synthetase activity of starved cells. Death was not altered by the presence of spermine or spermidine but was abolished by the methionine analogue, α-methylmethionine. Simultaneous starvation of another amino acid in a multiple auxotroph also significantly reduced
mld
, suggesting a possible role of protein synthesis. The onset of
mld
is correlated with a lower net increase of deoxyribonucleic acid.
Effects of the Recipient Strain and Ultraviolet Irradiation on Transduction Kinetics of the Penicillinase Plasmid of
Staphylococcus aureus
Authors: Rubin Sally J. , Rosenblum E. D.
Published: January 2020

When the penicillinase plasmid of
Staphylococcus aureus
PS 81(P
81
)(T
81
) was transferred to its cured derivative of PS 81(N
P
)(T
81
), there was a fivefold increase in the transduction frequency of penicillinase plasmid markers after ultraviolet (UV) irradiation of the phage instead of the expected decrease typical for plasmid-borne markers. These results were independent of the transducing phage, the donor, and the method of curing the recipient and were also obtained with a cured derivative of PS 80(PI
80
). With PS 52, a naturally occurring penicillin-sensitive strain, and a cured transductant of PS 52 as the recipients, typical plasmid kinetics were observed. The plasmid location of penicillinase plasmid markers in transductants was confirmed by their instability in ethidium bromide (EB). In a cross between isogenic plasmids (PI
258
penZ cad
× PI
258
penI asa ero
), transductants were doubly selected for cadmium and erythromycin resistances. There was a twofold increase in transduction frequency after UV irradiation of the transducing phage and an increase in the proportion of recombinant type transductants. CsCl-EB density centrifugation revealed that plasmid deoxyribonucleic acid (DNA) was present in PS 81(P
81
)(N
T
) and its cured derivative [PS 81(N
P
)(N
T
)], but not in PS 52. Sucrose gradient analysis of plasmid DNA showed that the penicillinase plasmid of PS 81(P
81
)(N
T
) was larger than the plasmid in its cured derivative. Thus, the cured derivative contains plasmid DNA which appears to recombine with the incoming plasmid, causing the rise in transduction frequency noted after UV irradiation of transducing phage.
Giant Cells of
Escherichia coli:
a Morphological Study
Authors: Allison David P.
Published: January 2020

Bacterial growth without division was observed in a giant cell-producing strain of
Escherichia coli
K-12. Giant cell production is controlled by the
lon
−
(failure of cell division after irradiation) and
mon
−
(formation of irregularly shaped cells) genes. Irradiation of a
lon
−
mon
−
strain (P678-A
4
) with low doses of ultraviolet or ionizing radiation results in the production of large, amorphous giant cells with 500 to 1,000 times the volume of the nonirradiated parents. The concentration of NaCl in the growth medium was found to influence irradiated-cell morphology. Low concentrations (0.2% NaCl) resulted in elongated cells, whereas spherical giant cells were produced in the presence of high salt (1% NaCl) concentrations.

Thin-section electron microscopy revealed an extensive network of intracellular membranes forming vacuoles, vesicles, and cisternae. These structures bear a striking resemblance to the rough and smooth membranes (endoplasmic reticulum, Golgi complex, vacuoles, etc.) found in eucaryotic cells.
Effect of Polymyxin on the Bacteriophage Receptors of the Cell Walls of Gram-Negative Bacteria
Authors: Koike Masaatsu , Iida Kyoko
Published: January 2020

Treatment of gram-negative bacteria with lethal doses of polymyxin B and colistin resulted in the formation of projections of the outer layer of the cell wall. Phages T3, T4, and T7, which use wall lipopolysaccharide as receptors, were specifically prevented from adsorbing toEscherichia coliB cells treated with polymyxin, whereas phages T1, T2, T5, and T6 were not. In the systems of phage P22C-Salmonella typhimuriumLT2 and phage C21-S. typhimuriumvariant SL1069, the phage were prevented from adsorbing to the host cell treated with the antibiotics. Electron microscopic observations show that phage T2 adsorbed irreversibly to the normal smooth surface between the projections on the outer layer caused by the drug treatment. These results indicate that lipopolysaccharide is affected by polymyxin functionally and morphologically, but lipoprotein is not. The purified lipopolysaccharide showed a ribbon-like structure when viewed face on and showed trilamellar structure when viewed edge on. The lipopolysaccharide fromE. coliB was irreversibly adsorbed by phages T3, T4, and T7, but not phage T2. Often, phage T4 adsorbed to both sides of the lipopolysaccharide strand at comparable distances. Phage P22C adsorbed through the spikes of the tail-plates to the lipopolysaccharide fromS. typhimuriumLT2. Lipopolysaccharide which was treated with low doses of the drug (2.5 to 6.25 μg of polymyxin B per ml to 100 μg of lipopolysaccharide per ml) turned into the coiled form and was partially broken down into short segments with coiled form. The loosely coiled lipopolysaccharide retains both its function as the receptor and its trilamellar structure. Treatment with high doses of the drug (12.5 to 25 μg of polymyxin B per ml to 100 μg of lipopolysaccharide per ml) caused the collapse of the trilamellar structure of the strand. These collapsed lipopolysaccharides became flat and fused with each other, making an amorphous mass, and finally they were broken into small collapsed fragments.
Membranous Structure of Purified
Escherichia coli
Lipopolysaccharide
Authors: Katayama Yutaka , Hattori Hiroshi , Suganuma Atsushi
Published: January 2020

The ultrastructure of the purified and lyophilized endotoxin from
Escherichia coli
O111 was observed by ultrathin sectioning. Onion-like globular membrane structures were observed in addition to rod-like and ribbon-like structures, indicating the existence of a globular membrane structure even in the dried state.
Thiamine-Binding Protein of
Escherichia coli
Authors: Iwashima Akio , Matsuura Atsuko , Nose Yoshitsugu
Published: January 2020

The ability to transport thiamine in
Escherichia coli
was reduced by osmotic shock treatment with a concomitant release of a thiamine-binding protein; its formation was repressed by thiamine added to the growth medium.
Direct Selection for Transduction of Suppressor Mutations and Linkage of
supD
to
fla
Genes in
Salmonella
Authors: Fankhauser David B. , Hartman Philip E.
Published: January 2020

A general method is presented for the direct selection of transductional clones of
Salmonella
containing suppressor mutations. The
supD
locus is about 40% cotransducible with the closest
fla
markers examined. The probable map order is:
supD501
-(
flaD42-flaB36
)-(
flaA41-flaA37
).
Nuclease Activities of
Mycoplasma gallisepticum
as a Function of Culture Age in Different Media
Authors: Cowen B. S. , Smith S. C.
Published: January 2020

Levels of deoxyribonuclease and ribonuclease activities in the supernatant (soluble plus ribosomes) fraction of
Mycoplasma gallisepticum
were assayed and found to be a function of strain, nutrient, and culture age. In yeast hydrolysate-enriched broth, maximal nuclease activities occurred during exponential growth.
Role of the Cytoplasmic Membrane in the Synthesis of Ribonucleic Acid by Disrupted Spheroplasts of
Pseudomonas schuylkilliensis
Authors: Mizuno Shigeki , Maruo Bunji
Published: January 2020

Disrupted spheroplast preparations of
Pseudomonas schuylkilliensis
strain
P
contained fragments of cytoplasmic membrane and approximately 82% of the total cellular phospholipid. The protoplast-bursting factor (PB-factor), partially purified from pig pancreas, and a heat-treated pancreatic lipase fraction both inhibited ribonucleic acid (RNA) synthesis by disrupted spheroplasts but did not inhibit or only slightly inhibited RNA synthesis by intact cells or intact spheroplasts. The PB-factor preparation and the heat-treated pancreatic lipase fraction catalyzed partial (15 to 50%) deacylation of diphosphatidylglycerol, phosphatidylglycerol, and phosphatidylethanolamine in disrupted spheroplasts but not in intact spheroplasts. Phospholipase A activity was demonstrated in the PB-factor preparation by use of isolated phospholipids as substrates. Treatment of disrupted spheroplasts with the PB-factor preparation caused a 70% inhibition in oxidative phosphorylation and RNA synthesis, but had little effect on electron transport. Addition of adenosine-5′-triphosphate or adenosine-5′-diphosphate and a mixture of ribonucleosides after treatment with the PB-factor preparation partially restored oxidative phosphorylation but did not relieve the inhibition in RNA synthesis. The most reasonable explanation for the latter observation appears to be that the concentrations of newly synthesized nucleotides retained by the preparations with partially deacylated membrane phospholipids were insufficient to permit the synthesis of RNA.