bluuebunny/crossref_metadata_2025 huggingface dataset:
Transformation and Physical Properties of R-Factor RP4 Transferred from
Escherichia coli
to
Rhizobium trifolii
Authors: O'Gara F. , Dunican L. K.
Published: January 2020

Transformation of R-factor RP4 specifying resistance to ampicillin, kanamycin, and tetracycline from
Escherichia coli
to
Rhizobium trifolii
is reported. Partially purified RP4 deoxyribonucleic acid (DNA) of the donor strain
E. coli
J5-3 that carried the R-factor was prepared by the lysozyme-ethylenediaminetetraacetic acid-Triton X-100 procedure and was used in transformation experiments with
R. trifolii
as recipient. The frequency of transformation of the R-factor into
R. trifolii
was 1.3 × 10
−4
. Dye buoyant density and sucrose gradient centrifugation of
R. trifolii
DNA showed that the expression of the specified drug resistance of RP4 by
R. trifolii
was accompanied by the acquisition of an extrachromosomal, satellite DNA component which has indistinguishable physical properties from the R-factor in the donor strain. The significance of the transformation is discussed.
Isolation and Characterization of Circular Deoxyribonucleic Acid Obtained from Lactose-Fermenting
Salmonella
Strains
Authors: Synenki R. M. , Wohlhieter J. A. , Johnson E. M. , Lazere Janet R. , Baron L. S.
Published: January 2020

Six
lac
elements originally contained in
Salmonella
strains were transferred to
Escherichia coli
WR3026. All of the six
E. coli
strains that received one of the
lac
elements were observed to contain supercoiled, circular deoxyribonucleic acid (DNA) when examined by the dye-buoyant density method. Segregants of each of these
E. coli
WR3026 strains that had lost the ability to utilize lactose, when examined in the same manner as the lactose-fermenting strains, were not observed to contain these supercoiled, circular DNA molecules. Thus the DNA of the
lac
elements is maintained in
E. coli
WR3026 in the supercoiled, circular form. Molecular weights of the supercoiled, circular molecules isolated from strains carrying the
lac
elements were determined by sucrose density gradient centrifugation to be 30 million to 56 million. The calculated number of copies per chromosome of the
lac
elements varied from 1.4 to 3.7, depending upon the particular
lac
element examined. Each of the elements was determined to have a guanine plus cytosine composition of 50%. All six of the
E. coli
WR3026 strains containing a transmissible
lac
element were tested with the
E. coli
male-specific phage, R-17, and the
E. coli
female-specific phage, φII, and did not respond to either of these phages as do F-containing derivatives of
E. coli
K-12.
Glucose Utilization and Ethanolic Fermentation by Wild Type and Extrachromosomal Mutants of
Neurospora crassa
Authors: Colvin H. J. , Sauer B. L. , Munkres K. D.
Published: January 2020

Logarithmic growth rates, maximal biomass, specific glucose utilization rates, and ethanol accumulation were measured in aerobic cultures of wild type and extrachromosomal mutants of
Neurospora crassa
. Maximal biomass and ethanol accumulation of wild type and [
mi-1
] were proportional to the initial glucose concentration in the range of 2 to 10%. The specific rates of glucose utilization by the mutants were 13- to 20-fold greater than those of wild type in young cultures. The specific rates of glucose utilization by wild type, however, were increased threefold by increasing the ammonium ion concentration in the preculture medium. The suppressor gene
f
+
suppressed the excessive glucose utilization and enhanced the growth rate and maximal biomass of [
mi-1
]. When the mutants were utilizing glucose at excessive rates, ethanol did not appear in the culture medium. Ethanol accumulation was maximum at stationary phase or thereafter, but there was little difference between the maxima of the mutants and wild type. The molar efficiency of the conversion of glucose to ethanol during the entire culture period of wild type and mutants was about 50% and, in the latter stages of fermentation, approached 100%. Replacement of ammonium ion by nitrate in the culture medium suppressed ethanol accumulation by wild type. The relationship of these results to previous observations on respiratory adaptation are discussed. We suggest that the Pasteur effect, the inhibition of fermentation by respiration, may be operative in
N. crassa
. Factors such as nitrogen source and concentration and oxygen tension, which may serve primarily to regulate the amount and form of respiration would, therefore, indirectly regulate fermentation. The mutants, although transiently deficient in terminal respiratory activity, do not accumulate more ethanol than wild type and, therefore, apparently do not ferment in excess to obtain additional adenosine 5′-triphosphate. We suggest that the excess activity of the alternate form of respiration of the mutants may be related to their excessive rate of glucose utilization by way of the pentose phosphate pathway and the oxidation of excess reduced nicotinamide adenine dinucleotide.
Abnormal Cell Envelope Ultrastructure of a
Saccharomyces
Mutant with Invertase Formation Resistant to Hexoses
Authors: Ghosh B. K. , Montenecourt B. , Lampen J. O.
Published: January 2020

The most obvious morphological characteristic of
Saccharomyces
mutant FH4C cells is the tendency to form clumps (production of invertase and α-glucosidase by this mutant is highly resistant to repression by hexoses). This peculiar feature arises from the abnormal cell envelope ultrastructure of the mutant. Clumps are formed as a result of the failure of the cell wall of the bud to separate from that of the mother cell. The cell wall also shows irregular thickening. There are many cells with a doughnut shape and with small budlike protrusions. Abnormal septation and wall invagination into vacuoles give rise to cells of differing sizes and irregular profiles. Many vesicles, tubules, and coiled membranous bodies originate from invaginations of the plasmalemma. These structures are frequently observed in the cell wall or the periplasmic space. The cells of mutant FH4C growing in 0.2 M glucose, unlike parent strain 303-67, contain many mitochondria. Large numbers of glycogen deposits are also found in many cells of FH4C.
Phospholipid Turnover in a Conditional Polyamine Auxotroph of
Escherichia coli
Authors: Munro George F. , Bell Carol A.
Published: January 2020

Polyamines are required for rapid phospholipid turnover in
Escherichia coli
growing in media of low osmolarity.
F Factor-Mediated Immunity to Lethal Zygosis in
Escherichia coli
K-12
Authors: Skurray Ronald A. , Reeves Peter
Published: January 2020

Recipient (F
−
) cells of
Escherichia coli
are sensitive to an excess of Hfr donor cells. This phenomenon of lethal zygosis is associated with conjugation and is observed as a continuous fall in F
−
viable cells during liquid mating, or as inhibition of F
−
growth on solid media. One class of survivors, which arose in the zones of inhibition on solid media, was no longer sensitive to lethal zygosis and exhibited the following properties: sensitivity to male-specific phage, donor ability, and surface exclusion. Since these characteristics were sensitive to acridine orange treatment, the strains carry an F factor extrachromosomally. They are, however, defective in some way since they retain sensitivity to female-specific phage. Temporary sensitivity to lethal zygosis in these and in standard F
+
strains can be induced by the formation of F
−
phenocopies. We have suggested that there is an immunity to lethal zygosis (Ilz
+
) associated with the F factor and discuss the results in terms of this hypothesis.
Biosynthesis of Glycosyldiglycerides in
Mycobacterium smegmatis
Authors: Schultz John C. , Elbein Alan D.
Published: January 2020

A particulate enzyme preparation from
Mycobacterium smegmatis
catalyzes the transfer of [
14
C]galactose from uridine 5′-diphosphate (UDP)-[
14
C]galactose and of [
14
C]glucose from UDP-[
14
C]glucose into chloroform-soluble products. The radioactive neutral lipids were purified by passage through diethylaminoethyl-cellulose, followed by thin-layer chromatography. When UDP-glucose was used as substrate, two major radioactive lipids were obtained; one had a hexose-glucose-glycerol ratio of 1:1:1. The second product had a hexose-glycerol ratio of 2:1 and, in addition to glucose, contained lesser amounts of mannose and galactose. With UDP-galactose as substrate, two radioactive products were observed that were chromatographically indistinguishable from the [
14
C]glucosyl-labeled mono- and diglycosyldiglyceride. Palmitate and oleate were the predominant fatty acid constituents in these lipids and were present in equimolar amounts in all of the products examined. The products have thus been identified as monoglycosyldiglyceride and a diglycosyldiglyceride containing glucose as the major hexose along with mannose and galactose. Properties of the galactosyl and glucosyl transferases are described.
Effect of Helium Gas at Elevated Pressure on Iron Transport and Growth of
Escherichia coli
Authors: Schlamm N. A. , Perry J. E. , Wild J. R.
Published: January 2020

Helium at an ambient pressure of 68 at m with 0.2 atm of O
2
shortened by 1 to 1.5 h the lag phase for growth of
Escherichia coli
in minimal medium supplemented with 2 μliters of cell-free culture filtrate (CFF) per ml or with 1 μM 2,3-dihydroxybenzoylserine (DHBS), an iron chelator. The lag phase of cultures not exposed to helium could be shortened by use of supplements, but higher concentrations were required—10 to 30 μliters of CFF per ml or 10 to 50 μM DHBS. Strain AN 193 of
E. coli
, which requires the DHBS precursor 2,3-dihydroxybenzoic acid (DHBA), grew well in media with 10 μM DHBA when exposed to helium at 68 atm, whereas 100 μM DHBA was required for growth in unexposed cultures. In the presence of 100 μM DHBA plus 1.0 μM ethylenediaminetetraactic acid, growth was inhibited at 1 and 68 atm. Growth was restored, however, by the addition of 0.1 μM FeSO
4
at 68 atm and 1.0 μM FeSO
4
at 1 atm, but lag times were invariably shorter in the pressurized cultures. Hydrostatic pressures of 68 atm did not reduce the lag phase in the presence of CFF, DHBS, or DHBA. Our results suggest that 68 atm of helium pressure, but not hydrostatic pressure, elicited a more rapid transport of iron into the cells.
Lipopolysaccharide from a Gram-Negative Marine Bacterium
Authors: Mongillo Anthony , Deloge Kenneth , Pereira Dennis , O'Leary Gerard P.
Published: January 2020

A lipopolysaccharide molecule was isolated from a marine bacterium. The molecule seems to be composed of lipid A and the hexoses, glucose and galactose.
Sporulation of
Saccharomyces cerevisiae
in the Absence of a Functional Mitochondrial Genome
Authors: Küenzi Martin T. , Tingle Marjorie A. , Halvorson Harlyn O.
Published: January 2020

The role of the mitochondrial system during sporulation of
Saccharomyces cerevisiae
was studied. Addition of ethidium bromide (EthBr) to cells growing in acetate medium resulted in the quantitative (>98%) conversion of the culture to the petite genotype in one generation. The cells were respiratory active (derepressed) but contained no mitochondrial deoxyribonucleic acid (mtDNA) as demonstrated by analytical ultracentrifugation in CsCl. When transferred to acetate sporulation medium, the culture sporulated. Ascus production was only slightly below that of the control culture. Synthesis of mtDNA occurred during sporulation in the control but not in the EthBr-treated culture. Mitochondrial protein synthesis was virtually eliminated in the EthBr-treated culture. Therefore, completely derepressed cells can sporulate without a functional mitochondrial genetic system. When partially repressed cells were treated with EthBr, no ascus formation was observed after transfer to sporulation medium. Control cultures underwent respiratory adaptation in sporulation medium and then sporulated. Extensive derepression of the respiratory system is thus required for sporulation, and this adaptation is dependent on a functional mitochondrial system. Our results suggest that once the cells are fully derepressed no mitochondrial genetic information has to be expressed during meiosis and ascus formation.
Isolation and Characterization of an
Escherichia coli ruv
Mutant Which Forms Nonseptate Filaments After Low Doses of Ultraviolet Light Irradiation
Authors: Otsuji Nozomu , Iyehara Hiroaki , Hideshima Yoko
Published: January 2020

Two ultraviolet light (UV)-sensitive mutants have been isolated from
Escherichia coli
K-12. These mutants, designated RuvA
−
and RuvB
−
, were controlled by a gene located close to the
his
gene on the chromosome map. They were sensitive to UV (10- to 20-fold increase) and slightly sensitive to gamma rays (3-fold increase). Host cell reactivation, UV reactivation and genetic recombination were normal in these mutants. Irradiation of the mutants with UV resulted in the production of single-strand breaks in deoxyribonucleic acid, which was repaired upon incubation in a growth medium. After UV irradiation, these mutants resumed deoxyribonucleic acid synthesis at a normal rate, as did the parent wild-type bacteria, and formed nonseptate, multinucleate filaments. From these results we concluded that the mutants have some defect in cell division after low doses of UV irradiation, similar to the
lon
−
or
fil
+
mutant of
E. coli
. The
ruv
locus was divided further into
ruvA
and
ruvB
with respect to nalidixic acid sensitivity and the effect of minimal agar or pantoyl lactone on survival of the UV-irradiated cell. The
ruvB
−
mutant was more sensitive to nalidixic acid than were
ruvA
−
and the parent strain. There was a great increase in the surviving fraction of the UV-irradiated
ruvB
−
mutant when it was plated on minimal agar or L agar containing pantoyl lactone. No such increase in survival was observed in the
ruvA
−
mutant.
Isolation of Germination Mutants of
Dictyostelium discoideum
Authors: Kessin Richard H. , Newell Peter C.
Published: January 2020

A simple method to separate spores from amoebae of
Dictyostelium discoideum
has been devized and used to isolate spore germination mutants. A subclass of these mutants is temperature sensitive for germination and growth.
Evidence Relating Cessation of Respiration, Cell Envelope Changes, and Death in Ultraviolet-Irradiated
Escherichia coli
B/r Cells
Authors: Swenson P. A. , Schenley R. L.
Published: January 2020

Ionic and nonionic detergents have little effect on respiring bacteria, but in cultures poisoned with KCN rapid solubilization of the cell membrane, as indicated by turbidity losses, takes place. Ultraviolet radiations cause
Escherichia coli
cells grown in minimal medium with glycerol as a carbon source to cease respiring and growing about 1 h after irradiation. We tested the effect of the nonionic detergent Triton X-100 on growth and cell membrane dissolution (both measured by turbidity changes), respiration, and viability of unirradiated and irradiated
E. coli
B/r cells. When the detergent was added to cells immediately after irradiation, a decrease in turbidity occurred only when respiration was about to cease; when it was added after cessation of respiration, the turbidity loss was immediate. In both cases the turbidity loss was about 60%, and disintegration of the cell walls did not take place. 5-Fluorouracil (FU) and thermal (42 C) treatments cause respiration of irradiated cells to be maintained and also cause viability increases. Irradiated cells treated with FU and detergent show no turbidity loss just prior to the time respiration normally ceases, but a loss does occur in irradiated cells incubated with detergent at 42 C. We conclude that FU maintains respiration for all of the cells, but that thermal treatment maintains respiration for only part of the cells. In all cases the detergent had only a negligible effect on the respiration and viability of unirradiated and irradiated cells. We conclude that Triton X-100 causes solubilization of cell membranes of only nonrespiring cells that are not destined to survive.
Modified Map Positions for
lac
and the
pro
Markers in
Escherichia coli
K-12
Authors: Broda Paul
Published: January 2020

Interrupted mating experiments were performed with Hfr strains H and C and three
leu lac purE
recipient strains derived from a common parent and carrying, respectively, the
proA
−
,
proB
−
, and
proC
−
mutations. It was concluded that if
leu
is placed at 1.5 min and
purE
at 12 min from
thr
, the origin on the Taylor-Trotter map,
lac
is at about 7.5 min and the
pro
genes are at about 6.0, 6.6, and 8.4 min, respectively. Both conjugational and transductional data suggest that the strain carrying the
proB
−
mutation also carries a second mutation close to the
proA
site which independently confers a Pro
−
phenotype. The times before the onset of transfer of chromosomal deoxyribonucleic acid by both Hfr strains B4 and B8 were approximately 3 min.
Transcription from the Complementary Deoxyribonucleic Acid Strands of
Bacillus subtilis
During Various Stages of Sporulation
Authors: Sumida-Yasumoto Chikako , Doi Roy H.
Published: January 2020

The messenger ribonucleic acid (mRNA) pattern of log-phase and sporulating cells of
Bacillus subtilis
has been analyzed by deoxyribonucleic acid (DNA)-RNA hybrid studies with the complementary-strand fragments of DNA. Approximately 80% of the mRNA of log-phase and sporulating cells from stages I, III, and IV hybridizes with the heavy DNA fragments, and 20% hybridizes with the light DNA fragments. Hybrid competition studies indicated that there was either a greatly reduced rate of transcription or a turn-off of some log-phase genes during the sporulation stages. However, a significant amount of log-phase gene transcription occurred even at late stages of sporulation. Similar studies indicate a significantly increased rate of transcription or a turn-on of sporulation phase genes during the latter stages of sproulation. There is a sequential increase in the amount of sporulation-specific transcription from both complementary-strand fragments of DNA. These results indicate that the RNA polymerase population in sporulating cells can transcribe both log-phase and sporulation-phase genes.
Factors Affecting the Activity and Stability of Alkaline Phosphatase in a Marine Pseudomonad
Authors: Thompson Linda M. M. , MacLeod Robert A.
Published: January 2020

Conditions optimum for the assay of alkaline phosphatase of marine pseudomonad B-16 (ATCC 19855) and for maintaining the activity of the enzyme have been determined. The pH for optimal activity of the cell-bound enzyme was 9.0, whereas that for the enzyme after its release from the cells exceeded 9.4. Release was effected by first washing the cells in 0.5 M NaCl and then suspending them in 0.5 M sucrose. In the absence of salts, the activity of the cell-bound enzyme decreased rapidly at 25 C and less rapidly at 4 C. This loss of activity could be arrested but not restored by adding Mg
2+
. In the presence of Na
+
, activity of the cell-bound enzyme dropped to about 50% of that prevailing initially, but in this case adding Mg
2+
restored enzyme activity completely. The activity of the enzyme after its release from the cells into 0.5 M sucrose was approximately 50% of that of the equivalent amount of enzyme in the original cells. This activity was relatively stable at both 25 and 4 C. Adding Mg
2+
to the released enzyme restored its activity to that of the cell-bound form. The synthesis of alkaline phosphatase by the cells was not affected by adding 50 mM inorganic phosphate to the growth medium. The

K
m

of the released enzyme for
p
-nitrophenyl phosphate was found to be 6.1 × 10
−5
M.
Transduction with Integration-Defective Mutants of
Salmonella typhimurium
Bacteriophage KB1
Authors: McIntire Sarah A.
Published: January 2020

Phage KB1 has gained use as a generalized transducing phage for
Salmonella typhimurium
, including strains resistant to phage P22. Integration-defective mutants of KB1 have now been isolated; one of these,
int-1
, is recommended for transduction when nonlysogenic recombinants are desired.
Sodium-Stimulated Glutamate Transport in Osmotically Shocked Cells and Membrane Vesicles of
Escherichia coli
Authors: Miner Karen M. , Frank Leonard
Published: January 2020

Three phenotypically distinct strains of
Escherichia coli
B were studied: one in which the transport of glutamate was strongly stimulated by sodium, one in which the transport was relatively independent of sodium, and one which did not transport glutamate. Membrane vesicle preparations from the three strains followed the behavior of whole cells with respect to sodium-stimulated transport. Although glutamate-binding material could be released from cells by osmotic shock, its affinity for glutamate was not significantly influenced by sodium. Furthermore, the shocked cells retained sodium-stimulated transport. The accumulated results suggest that the sodium-activated glutamate transport system resides in the cytoplasmic membrane and that releasable binding protein(s) is not intimately involved in its function.
De Novo Purine Synthesis in Vegetative Cells and Myxospores of
Myxococcus xanthus
Authors: Westby Carl A. , Tsai Wen-Cherng
Published: January 2020

This study was designed to determine whether vegetative cells and myxospores of
Myxococcus xanthus
were capable of classical de novo purine biosynthesis. To answer this question, vegetative and myxospore extracts of
M. xanthus
FBa were tested for their ability to synthesize the second de novo intermediate, 5′-phosphoribosylglycinamide, from beginning precursors either by way of phosphoribosyl-pyrophosphate amido transferase (EC 2.4.2.14) or ribose-5-phosphate amino transferase. Both the amido and amino transferase routes occurred in both types of extracts, and both enzymes appear to be present at about the same level (per milligram of protein) in vegetative cells, myxospores, and in a bacterial prototype,
Salmonella typhimurium
. The dose response of the vegetative and myxospore forms of both enzymes towards adenosine 5′-monophosphate (AMP) and guanosine 5′-monophosphate (GMP) suggests that the allosteric structure of both enzymes is changed little by sporulation. Both enzymes were inhibited to varying degrees by a variety of purine nucleotides besides AMP, GMP, and 3′:5′ cyclic AMP.
Amino Acid Pools and Metabolism During the Cell Division Cycle of Arginine-Grown
Candida utilis
Authors: Nurse P. , Wiemken A.
Published: January 2020

Synchronous cultures obtained by isopycnic density gradient centrifugation are used to investigate amino acid metabolism during the cell division cycle of the food yeast
Candida utilis
. Isotopic labeling experiments demonstrate that the rates of uptake and catabolism of arginine, the sole source of nitrogen, double abruptly during the first half of the cycle, while the cells undergo bud expansion. This is accompanied by a doubling in rate of amino acid biosynthesis, and an accumulation of amino acids. The accumulation probably occurs within the storage pools of the vacuoles. Amino acids derived from protein degradation contribute little to this accumulation. For the remainder of the cell cycle, during cell separation and until the next bud initiation, the rates of uptake and catabolism of arginine and amino acid biosynthesis remain constant. Despite the abrupt doubling in the rate of formation of amino acid pools, their rate of utilization for macromolecular synthesis increases steadily throughout the cycle. The significance of this temporal organization of nitrogen source uptake and amino acid metabolism during the cell division cycle is discussed.
Role of Catechol and the Methylcatechols as Inducers of Aromatic Metabolism in
Pseudomonas putida
Authors: Murray Keith , Williams Peter A.
Published: January 2020

Pseudomonas putida
NCIB 10015 metabolizes phenol and the cresols (methylphenols) by the
meta
pathway and metabolizes benzoate by the
ortho
pathway. Growth on catechol, an intermediate in the metabolism of both phenol and benzoate, induces both
ortho
and
meta
pathways; growth on 3- or 4-methylcatechols, intermediates in the metabolism of the cresols, induces only the
meta
pathway to a very limited degree. Addition of catechol at a growth-limiting rate induces virtually no
meta
pathway enzymes, but high levels of
ortho
pathway enzymes. The role of catechol and the methylcatechols as inducers is discussed. A method is described for assaying low levels of catechol 1,2-oxygenase in the presence of high levels of catechol 2,3-oxygenase and vice versa.
Polyamine Levels During Growth, Sporulation, and Spore Germination of
Bacillus megaterium
Authors: Setlow Peter
Published: January 2020

Spermidine was the major (>95%) polyamine of
Bacillus megaterium
in all stages of growth, although it could be replaced completely by spermine. Log-phase cells had 40 to 50% as much spermidine, based on ribonucleic acid (RNA) content, as did either stationary-phase cells or dormant spores; similar results were obtained in three other bacilli including an asporogenous mutant. Polyamine levels were essentially the same in
B. megaterium
grown in rich or poor media, or in media of high or low ionic strength. Polyamine levels were elevated three- to sixfold by exogenous spermidine without a major effect on growth, sporulation, or subsequent spore germination. During germination, the absolute amount of spermidine remained constant for almost 2 h until net RNA synthesis had lowered the polyamine/RNA ratio to a value close to that in log-phase cells. At this time, the spermidine level began to rise, and thereafter spermidine and RNA increased in parallel. This parallel relationship between the spermidine and RNA levels was abolished by actinomycin D, but not by chloramphenicol.
Growth of Ribonucleic Acid Bacteriophage f2 in a Conditional Putrescine Auxotroph of
Escherichia coli
: Evidence for a Polyamine Role in Translation
Authors: Young Delano V. , Srinivasan P. R.
Published: January 2020

The ribonucleic acid (RNA) bacteriophage, f2, grows poorly in a conditional putrescine auxotroph during polyamine starvation. The addition of putrescine simultaneously with f2 enhances phage growth, shortens the latent period, and increases the burst size. The stimulation of f2 growth is reflected in higher rates of phage RNA and protein syntheses as measured by radioactive labeling of infected cells in the presence of rifampin. Putrescine does not affect f2 adsorption or the penetration of its RNA. Rather, in vitro assays demonstrate that in putrescine-supplemented cells more molecules of f2 replicase are made per incoming parental RNA than in polyamine-starved cultures. The ability of polyamines to stimulate the translation of a preformed messenger suggests a physiological role for these organic cations in normal protein synthesis.
Cyanide Formation from Oxidation of Glycine by a
Pseudomonas
Species
Authors: Wissing Frode
Published: January 2020

With whole cells of a hydrogen cyanide-producing bacterium strain C, of the genus
Pseudomonas
, it was found that the oxygen necessary for the oxidation of glycine to cyanide could be replaced by various artificial electron acceptors. The order of reactivity was: oxygen > phenazine methosulphate > methylene blue > 2,6-dichlorophenolindophenol > ferricyanide. Cyanide production was inhibited by pyrrolnitrin, a well-known inhibitor of many flavine enzymes. The molar ratio of added glycine to cyanide produced was found to be 1.09. With whole bacteria the apparent

K
m

(glycine) for the cyanide production was found to be 5.0 × 10
−4
M.
Regulation of Bacterial Cell Division: Genetic and Phenotypic Analysis of Temperature-Sensitive, Multinucleate, Filament-Forming Mutants of
Escherichia coli
Authors: Allen Jane Smith , Filip Camille C. , Gustafson Ralph A. , Allen Robert G. , Walker James R.
Published: January 2020

Three mutants of
Escherichia coli
K-12 which form filaments during 42 C incubation have been characterized. The mutant strains AX621, AX629, and AX655 continued to grow and to synthesize deoxyribonucleic acid at 42 C for 150 to 180 min, after which time growth ceased. When cultures of the mutants were transferred from 42 to 28 C, septation of the filaments began after a 25- to 30-min period and continued at a greater than normal rate until no filaments remained. Addition of chloramphenicol at the time of transfer from 42 to 28 C prevented cell division in strain AX655 and caused lysis of strains AX621 and AX629. The temperature sensitivity mutation in each strain mapped near
leu
. For strain AX621, the mutation was specifically located between
leu
and
nadC
by P1 transduction. Properties of these strains are compared with those of other cell division mutants.
Clonal Analysis of Cell Division in the
Bacillus subtilis div IV-B1
Minicell-Producing Mutant
Authors: Coyne Sheila I. , Mendelson Neil H.
Published: January 2020

Spores of the
Bacillus subtilis
minicell-producing mutant
div IV-B1
were germinated and grown to microcolonies in chambers which facilitate continuous observation of the developing clones with a phase-contrast microscope. Time lapse photographs were taken of 46 clones, covering the period from the beginning of outgrowth until at least two rounds of cell division had been completed. Cell lineages were constructed from contour length measurements of the photographs. These data include cell lengths, division site locations, and cell numbers in clones of various ages. From these data we have determined that the probability of a minicell being produced at any division by the
div IV-B1
mutant is 0.31. The location of the abnormal division site which generates the first minicell produced in the outgrowing clone appears to be random with respect to the existing cell poles. In contrast, the location of the second abnormal division site, and hence the second minicell, is not random but rather occurs preferentially in proximity to the first minicell. This clustering of abnormal events suggests that division site location is related to pole age (generations), although other influences on minicell clustering cannot be ruled out at present.
Influence of Protein and Ribonucleic Acid Synthesis on the Replication of the Bacteriocinogenic Factor Clo DF13 in
Escherichia coli
Cells and Minicells
Authors: Veltkamp E. , Barendsen W. , Nijkamp H. J.
Published: January 2020

The influence of ribonucleic acid (RNA) and protein synthesis on the replication of the cloacinogenic factor Clo DF13 was studied in
Escherichia coli
cells and minicells. In chromosomeless minicells harboring the Clo DF13 factor, Clo DF13 deoxyribonucleic acid (DNA) synthesis is slightly stimulated after inhibition of protein synthesis by chloramphenicol or puromycin and continues for more than 8 h. When minicells were treated with rifampin, a specific inhibitor of DNA-dependent RNA polymerase, Clo DF13 RNA and DNA synthesis appeared to stop abruptly. In cells, the Clo DF13 factor continues to replicate during treatment with chloramphenicol long after chromosomal DNA synthesis ceases. When rifampin was included during chloramphenicol treatment of cells, synthesis of Clo DF13 plasmid DNA was blocked completely. Isolated, supercoiled Clo DF13 DNA, synthesized in cells or minicells in the presence of chloramphenicol, appeared to be sensitive to ribonuclease and alkali treatment. These treatments convert a relatively large portion of the covalently closed Clo DF13 DNA to the open circular form, whereas supercoiled Clo DF13 DNA, isolated from non-chloramphenicol-treated cells or minicells, is not significantly affected by these treatments. These results indicate that RNA synthesis and specifically Clo DF13 RNA synthesis are involved in Clo DF13 DNA replication and that the covalently closed Clo DF13 DNA, synthesized in the presence of chloramphenicol, contains one or more RNA sequences. De novo synthesis of chromosomal and Clo DF13-specific proteins is not required for the replication of the Clo DF13 factor. Supercoiled Clo DF13 DNA, isolated from a polA107 (Clo DF13) strain which lacks the 5′ → 3′ exonucleolytic activity of DNA polymerase I, is insensitive to ribonuclease or alkali treatment, indicating that in this mutant the RNA sequences are still removed from the RNA-DNA hybrid.
Effect of Thymine-5-Bromouracil Substitution on F Pili
Authors: Fives-Taylor Paula , Novotny Charles P.
Published: January 2020

The effect of thymine-5-bromouracil substitution on the regeneration and length of F pili produced by an F
+
Lac
+
/Lac
−
Thy
−
strain of
Escherichia coli
was studied by electron microscopy. When 5-bromouracil (5BU) incorporation into deoxyribonucleic acid (DNA) was maximal, the modal length of the pilus doubled and the number of pili per cell was approximately 50% that of thymine-grown cells. The ability of 5BU-grown cells to form mating pairs and to be infected by ribonucleic acid (R17) and DNA (M13) male-specific phages was also reduced by approximately 50%. Loss of function was not due to loss of sex factor as 5BU cells retained a sex factor that was susceptible to curing by acridine orange. Elongation of pili on 5BU-grown cells was more sensitive to irradiation at 253.7 nm than on thymine-grown cells, suggesting that DNA is the sensitive target.
Use of Ultraviolet Radiation to Locate Dipicolinic Acid in
Bacillus cereus
Spores
Authors: Germaine G. R. , Murrell W. G.
Published: January 2020

A novel method is described that allows a direct determination of the location of a portion of the dipicolinic acid (DPA) in spores. Ultraviolet (UV) irradiation is shown to cause cross-linkage of DPA to spore proteins which have the characteristics of membrane proteins. We suggest that DPA resides in the inner forespore membrane (IFSM) and spore cytoplasm (i.e., the spore protoplast). Only that portion of the DPA in the vicinity of the IFSM appeared to form UV-induced DPA-protein adducts.
Identification of Messenger Ribonucleic Acids and Proteins Synthesized by the Bacteriocinogenic Factor Clo DF13 in Purified Minicells of
Escherichia coli
Authors: Kool A. J. , van Zeben M. S. , Nijkamp H. J. J.
Published: January 2020

It has previously been shown that the cloacinogenic factor Clo DF13 (Clo DF13) segregates into minicells of strain
Escherichia coli
P678-54 that harbors Clo DF13 and that this Clo DF13 factor is the only deoxyribonucleic acid (DNA) present in these otherwise chromosomeless minicells. The study reported here shows that minicells prepared from P678-54(Clo DF13) are able to incorporate radioactive precursors into ribonucleic acid (RNA) and protein. The RNA synthesized in these purified minicells is Clo DF13 specific, as shown by RNA-DNA hybridization experiments. The results indicate that all the de novo synthesized gene products in Clo DF13 minicells are Clo DF13 specific. Polyacrylamide gel electrophoretic patterns show that in these minicells at least three polypeptides (molecular weight about 70,000, 20,000, and 11,000) and one major species of messenger RNA (mRNA) (
S
value about 21.3) are synthesized. To investigate the factor in its induced state, we isolated a Clo DF13 mutant with an enhanced level of cloacin production. Minicells harboring this Clo DF13 mutant produce five additional polypeptides (molecular weight about 58,000, 44,000, 28,000, 16,000, and 14,000). Three additional mRNA species (
S
value about 19.5, 14, and 12) could be distinguished. The total molecular weight of the eight polypeptides corresponds to 85% of the total coding capacity of the mRNAs (303,000). The total molecular weight of the four mRNAs is 2.55 × 10
6
, which covers 85% of the Clo DF13 DNA (molecular weight 6 × 10
6
).
Cytochemical Localization of Polysaccharides in
Claviceps paspali
Ultrastructure During Submerged Fermentation of Alkaloids
Authors: Voříšek J. , Ludvík J. , Řeháček Z.
Published: January 2020

Morphological characteristics of two types of elements in the submerged mycelium of
Claviceps paspali
are described. Distribution of polysaccharides in the cell wall and cytoplasm was cytochemically determined at the ultrastructural level. Polysaccharide deposition into the cell walls was proportional to the increase in the alkaloid yield. In the cytoplasm, on the other hand, the presence of polysaccharide grains indicated an absence of alkaloid synthesis.
Effect of Temperature on the Distribution of Membrane Particles in
Streptococcus faecalis
as Seen by the Freeze-Fracture Technique
Authors: Tsien H. C. , Higgins M. L.
Published: January 2020

When cells of
Streptococcus faecalis
ATCC 9790 were incubated at temperatures above 10 C before being frozen for freeze-fracture, a random distribution of particles was observed on the outer fracture face of the freeze-cleaved cell membrane. However, when cells were incubated below 10 C before freezing, particleless patches were seen on this membrane surface. The size of the patches produced on chilling could be increased by centrifugation or by storing the chilled cells overnight at about 3 C. Patch formation appeared readily reversible, since the medium and large patches that formed on chilling could not be observed in cells warmed for 10 s at 25 C. However, during the transition from the patch to patchless state, smaller patches not seen in the chilled cells were observed. This suggested that the smaller patches might have been intermediate forms produced by the fragmentation of larger patches on warming.
Osmiophilic Structure in Pigment-Producing
Flavobacterium
Mutants
Authors: Bauer Heinz , Shepherd David , Sigarlakie Elsje
Published: January 2020

A highly osmiophilic structure observed in all pigment-producing mutants of
Flavobacterium
examined is described. Several factors favor the possibility that this structure might be related to pigment synthesis or pigment accumulation.
Assembly of Hybrid Flagellar Filaments
Authors: Silverman Michael , Simon Melvin
Published: January 2020

The distribution of flagellin subunits in flagellar filaments synthesized by merodiploid strains carrying two distinguishable
hag
loci has been examined. The filament was found to be a homogeneous co-polymer of the two subunits. This suggests that the subunits may be able to mix freely before being assembled.
Percent Charging of Transfer Ribonucleic Acid and Levels of ppGpp and pppGpp in Dormant and Germinated Spores of
Bacillus megaterium
Authors: Setlow Peter
Published: January 2020

The levels of transfer ribonucleic acids (tRNAs) specific for 14 amino acids were almost identical in dormant spores and in spores germinated from 6 to 75 min. Germinated spore tRNAs specific for all amino acids tested were between 63 and 93% charged, and there was no significant change in this value from 6 to 75 min of germination. In contrast, tRNAs isolated from dormant spores specific for nine different amino acids were almost completely(>93%) uncharged. However, some dormant spore tRNAs, i.e., those for arginine, histidine, isoleucine, and valine, showed significant (21 to 72%) levels of aminoacylation. Dormant spores contained no detectable guanosine penta- (pppGpp), tetra- (ppGpp), or triphosphate (GTP). However, these nucleotides appeared in the first minutes of germination, and thereafter all increased in parallel with a ratio of pppGpp plus ppGpp to GTP of 0.07 to 0.11, which is characteristic of unstarved vegetative cells.
Cell Envelope Morphology of Rumen Bacteria
Authors: Costerton J. W. , Damgaard H. N. , Cheng K.-J.
Published: January 2020

The cell walls of three species of rumen bacteria (Bacteroides ruminicola, Bacteroides succinogenes, andMegasphaera elsdenii) were studied by a variety of morphological methods. Although all the cells studied were gram-negative and had typical cytoplasmic membranes and outer membranes, great variation was observed in the thickness of their peptidoglycan layers.Megasphaera elsdeniievidenced a phenomenally thick peptidoglycan layer whose participation in septum formation was very clearly seen. All species studied have cell wall “coats” external to the outer membrane. The coat ofBacteroides ruminicolais composed of large (approximately 20 nm) globules that resemble the protein coats of other organisms, whereas the coat ofBacteroides succinogenesis a thin and irregular carbohydrate coat structure.Megasphaera elsdeniidisplays a very thick fibrillar carbohydrate coat that varies in thickness with the age of the cells. Because of the universality of extracellular coats among rumen bacteria we conclude that the production of these structures is a protective adaptation to life in this particular, highly competitive, environment.
Electron Microscopy of the Cell Wall ofRickettsia prowazeki
Authors: Palmer E. L. , Mallavia L. P. , Tzianabos T. , Obijeski J. F.
Published: January 2020

PurifiedRickettsia prowazekiwere found to undergo morphological changes resembling plasmolysis when stained with uranyl acetate, resulting in rod-like forms. Sequential electron micrographs of disintegrating organisms provide evidence for the cell wall origin of these rod-like forms. The substructure of the cell wall was discerned by using negative-contrast electron microscopy. The wall was found to be composed of repetitive subunits with a periodicity of 13 nm and was surrounded by a thin membrane.
Physiological Influences on Cell Division Patterns in the
div IV-B1
Minicell-Producing Mutant of
Bacillus subtilis
Authors: Mendelson Neil H. , Keener Sherry L.
Published: January 2020

The proportion of abnormal divisions resulting in minicells is influenced by growth stage and medium composition.
Effect of Competence Induction on Macromolecular Synthesis in a Group H Streptococcus
Authors: Horne Diane S. , Perry Dennis
Published: January 2020

The effects of competence induction by competence factor (CF) on macromolecular synthesis in group H streptococcus strain Wicky were investigated. CF preparations (culture filtrates from competent group H streptococcus strain Challis) were either heated or partially purified to remove a bacteriocin. These preparations did not inhibit growth, although they induced high levels of competence in strain Wicky. The action of the CF preparations did not affect the overall rates of deoxyribonucleic acid and protein synthesis, but caused a reduction in the rates of ribonucleic acid (RNA) and peptidoglycan synthesis. When competence induction by CF was prevented, no alterations in RNA or peptidoglycan synthesis were observed, indicating that these changes are in fact related to the development of competence.
Round of Replication Mutant of a Drug Resistance Factor
Authors: Morris C. F. , Hashimoto H. , Mickel S. , Rownd R.
Published: January 2020

A derivative of the R factor
NR1
(called R12) has been isolated which undergoes an increased number of rounds of replication each division cycle in
Proteus mirabilis, Escherichia coli
, and
Salmonella typhimurium
. The alteration resulting in the increased number of copies (round of replication mutation) is associated with the transfer factor component of the R factor. R12 has the same drug resistance pattern as
NR1
, is the same size as shown by sedimentation in a sucrose gradient and electron microscopy (63 × 10
6
daltons), and has the same partial denaturation map. The level of the R factor gene product chloramphenicol acetyltransferase has been examined in
P. mirabilis
and was found to be consistent with gene dosage effects. The plasmid to chromosomal deoxyribonucleic acid ratio of
NR1
increases several fold after entry into stationary phase, whereas this ratio for R12 remains approximately constant. Individual copies of R12 are selected at random for replication from a multicopy plasmid pool. A smaller percentage of R12 copies replicate during amino acid starvation than has previously been found for
NR1
in similar experiments.
Purification and Properties of Undecyl Acetate Esterase from
Pseudomonas cepacia
Grown on 2-Tridecanone
Authors: Shum A. C. , Markovetz A. J.
Published: January 2020

Undecyl acetate esterase has been purified from
Pseudomonas cepacia
grown on the methyl ketone, 2-tridecanone. The

K
m

for undecyl acetate was 2.3 × 10
−2
M. Polyacrylamide gel electrophoresis indicated that two esterase bands were being recovered during purification. These bands were separated by preparative polyacrylamide gel electrophoresis. Molecular weights were estimated to be approximately 34,500 by several methods. Molecular sieve polyacrylamide gel electrophoresis indicated that the two esterases had the same molecular weight but different charge, which is indicative of isoenzymes.
Genetic Analysis of a Temperature-Resistant Revertant of the Conditional Lethal
Escherichia coli
Double Mutant
polA12 uvrE502
Authors: Smirnov G. B. , Saenko A. S.
Published: January 2020

Conditional lethality of the
Escherichia coli polA12 uvrE502
double mutant may be overcome by a mutation that has been termed
polA350
. The
polA350
mutation restored the polymerizing activity of deoxyribonucleic acid polymerase I at 42 C in the
polA12
mutant and partially suppressed ultraviolet (UV) and methylmethane sulfonate sensitivities of the
polA12
. Mapping experiments have located
polA350
between
metE
and
polA12
, very close to the latter. The strain carrying
polA12 polA350
and
recB21
was viable at 42 C. The effects of the
recB21
and
polA12 polA350
combination on the UV sensitivity were additive. The triple mutant
polA12 polA350 uvrE502
was more UV sensitive than the single
uvrE502
mutant.
Isolation and Characterization of the Outer Membrane of
Neisseria gonorrhoeae
Authors: Johnston K. H. , Gotschlich E. C.
Published: January 2020

The cell envelope of
Neisseria gonorrhoeae
strain 2686, colonial type 4, was isolated from spheroplasts formed by the action of ethylenediaminetetraacetic acid and lysozyme. Isopycnic centrifugation of osmotically ruptured spheroplasts resolved the cell envelope into two main membrane fractions. Chemical and enzymatic analyses were used to characterize these isolated membranes. Succinic dehydrogenase, reduced nicotinamide adenine dinucleotide oxidase, and
d
-lactate dehydrogenase were localized in the membrane fraction of buoyant density, ρ° = 1.141 g/cm
3
. Lipopolysaccharide and over half of the cell envelope protein were associated with the membrane that banded in sucrose at ρ° = 1.219 g/cm
3
. These fractions were consequently designated cytoplasmic and outer or L-membrane, respectively. Sodium dodecyl sulfate-polyacrylamide electrophoresis of isolated membranes demonstrated the relative simplicity of the protein spectrum of the outer membrane. The majority of the protein in this membrane could be accounted for by proteins of molecular weights 34,500, 22,000, and 11,500. The protein of molecular weight 34,500 accounted for 66% of the total protein of the L-membrane. Isoelectric precipitation at pH 4.6 with 10% acetic acid selectively removed this protein from a 150 mM NaCl in 10 mM tris(hydroxymethyl)aminomethane-hydrochloride, pH 7.4, extract of purified outer membrane. At pH 4.0, the other proteins of the L-membrane were precipitated. It was concluded that the membrane components of the cell envelope of
N. gonorrhoeae
were similar to those of other gram-negative bacteria. The cell envelope fractions described here, in particular the outer membrane, are sufficiently well defined to provide a valuable tool for future biochemical and immunological studies on
N. gonorrhoeae
.