bluuebunny/crossref_metadata_2025 huggingface dataset:
Induction of Spherule Formation in
Physarum polycephalum
by Polyols
Authors: Chet I. , Rusch H. P.
Published: January 2020

A method has been developed for inducing spherule formation (spherulation) in the myxomycete
Physarum polycephalum
by transferring the culture to synthetic medium containing 0.5
m
mannitol or other polyols. This morphogenetic process occurred within 12 to 35 hr after the inducer was added. The mature spherules existed as distinct morphogenetic units, in contrast to the clusters of spherules formed during starvation. Ninety per cent of the spherules germinated by 24 hr in synthetic medium. The changes in the synthesis of ribonucleic acid (RNA), deoxyribonucleic acid (DNA), and protein during plasmodial growth, spherulation, and germination of spherules are described. When spherule formation was completed, RNA, protein, and DNA decreased, compared with the values at the beginning of the conversion. The incorporation of
3
H-uridine into trichloroacetic acid-insoluble material was different in each of these periods, and this incorporation was sensitive to actinomycin D. The amount of glycogen increased during growth, whereas it decreased during spherulation.
14
C-glucose could be taken up by the cells in the presence of the inducer, and mannitol could not replace glucose as a source of energy. The mode of action of mannitol and its mechanism of induction are discussed.
Alternative Developmental Pathways Determined by Environmental Conditions in the Cellular Slime Mold
Dictyostelium discoideum
Authors: Newell Peter C. , Telser Alvin , Sussman Maurice
Published: January 2020

The cellular slime mold
Dictyostelium discoideum
grows in the soil as a population of independent, uninucleate amoebae. Upon entrance to the stationary phase, the amoebae collect in multicellular aggregates to form organized fruiting bodies composed of spores and stalk cells. Depending upon environmental conditions, the developing aggregate either constructs the fruiting body at the site of aggregation or transforms into a structure that can migrate to a more favorable location. Environmental conditions that favor migration are (i) the accumulation of metabolite(s) produced by the aggregate and (ii) a low ionic strength in the substratum. Conditions that prevent migration or that stop a migrating slug are (i) the presence of buffer and (ii) illumination by overhead light.
Regulation of Protein Synthesis in Zoospores of
Blastocladiella
Authors: Schmoyer Irvin R. , Lovett James S.
Published: January 2020

The factors responsible for the regulation of protein synthesis in the zoospores of
Blastocladiella emersonii
were studied by means of cell fractionation and in vitro assays. Charged transfer ribonucleic acid (tRNA) and aminoacyl-tRNA synthetases were found both inside the membrane-bound, ribosomal nuclear cap, and in the extracap cytoplasm. Ribosomes isolated from zoospore nuclear caps in low salt buffer failed to support polyuridylic acid-dependent phenylalanine incorporation. After washing with high salt buffer, the cap ribosomes were equivalent in activity to similarly prepared plant ribosomes. Both the high-salt wash from cap ribosomes and the extracap supernatant fraction contained an unidentified material which inhibited aminoacyl-tRNA binding and peptide bond formation by ribosomes. Ribosomal binding of polyuridylic acid was not inhibited. Washed cap ribosomes supported very low incorporation rates without added messenger RNA, and were highly dependent upon added poly U for phenylalanine incorporation, indicating a low level of messenger in nuclear caps. It is concluded that enclosure of the ribosomes in the nuclear cap does not in itself prevent protein synthesis, and that the lack of activity may be due to the presence of a ribosome inhibitor.
Amino Acid Composition and Terminal Sequences of Ferredoxins from Two Photosynthetic Green Bacteria
Authors: Rao K. K. , Matsubara H. , Buchanan B. B. , Evans M. C. W.
Published: January 2020

The amino acid composition of ferredoxins from
Chlorobium thiosulfatophilum
8327 and
Chloropseudomonas ethylicum
, like
C. thiosulfatophilum
Tassajara, resembled ferredoxins from nonphotosynthetic anaerobes rather than
Chromatium
; the terminal sequences, however, more closely resembled
Chromatium
ferredoxin.
Metabolic Turnover of the Polar Lipids of
Mycoplasma laidlawii
Strain B
Authors: McElhaney Ronald N. , Tourtellotte Mark E.
Published: January 2020

The fatty acyl groups of the membrane polar lipids of
Mycoplasma laidlawii
B were radioactively labeled by growth in the presence of
14
C-palmitic, oleic, or linoleic acids. No loss of radioactivity from any of the polar lipids occurred during incubation of radiolabeled cells in growth medium containing various nonradioactive fatty acids, although growth and lipid biosynthesis continued throughout the incubation period. The metabolism of the glucose and phosphate moieties was also studied in a similar fashion by utilizing growth in
14
C-glucose or
32
P-inorganic phosphate to radioactively label these groups. As before, no loss of radioactivity from any of the polar lipids occurred during subsequent growth in medium containing unlabeled glucose or phosphate. The results establish that the glyco- and phospholipids of
M. laidlawii
B are metabolically stable in actively growing cells. The absence of metabolic turnover is discussed in terms of proposed relationships between lipid metabolism and function in this organism.
Electromechanical Interactions in Cell Walls of Gram-Positive Cocci
Authors: Ou Li-Tse , Marquis Robert E.
Published: January 2020

Isolated cell walls of
Staphylococcus aureus
and
Micrococcus lysodeikticus
were found to expand and contract in response to changes in environmental
p
H and ionic strength. These volume changes, which could amount to as much as a doubling of wall dextran-impermeable volume, were related to changes in electrostatic interactions among fixed, ionized groups in wall polymers, including peptidoglycans.
S. aureus
walls were structurally more compact in the hydrated state and had a higher maximum charge density than
M. lysodeikticus
walls. However, they were less responsive to changes in electrostatic interactions, apparently because of less mechanical compliance. In media of nearly neutral
p
H,
S. aureus
walls had a net positive charge whereas
M. lysodeikticus
walls had a net negative charge. These charge differences were reflected in Donnan distributions of mobile ions between wall phases and bulk medium phases. Cell walls of unfractionated cocci also could be made to swell and contract, and wall tonus in intact cells appeared to be set partly by electrostatic interactions and partly by mechanical tension in the elastic structures due to cell turgor pressure. The experimental results led to the conclusions that bacterial cell walls have many of the properties of polyelectrolyte gels and that peptidoglycans are flexible polymers. A reasonable mechanical model for peptidoglycan structure might be a sort of three-dimensional rope ladder with relatively rigid, polysaccharide rungs and relatively flexible polypeptide ropes. Thus, the peptidoglycan network surrounding cocci appeared to be predominantly an elastic restraining structure rather than a rigid shell.
Tryptophanless Death in
Bacillus subtilis
Authors: Majerfeld Irene , Barlati Sergio , Ciferri Orio
Published: January 2020

A decline in colony-forming ability is observed in actively growing cultures of a tryptophan arginine auxotroph of
Bacillus subtilis
after removal of tryptophan (tryptophanless death). This phenomenon can be prevented by simultaneous starvation of the other required amino acid or by chloramphenicol administered in bacteriostatic concentration but not by actinomycin. Addition of tryptophan analogues not only prevents the death but also allows recovery of the cells that have lost the ability to form colonies on solid media. The term tryptophanless death is therefore inappropriate. Chloramphenicol but not actinomycin inhibits the recovery brought about by tryptophan analogues.
Mutants of
Diplococcus pneumoniae
that Lack Deoxyribonucleases and Other Activities Possibly Pertinent to Genetic Transformation
Authors: Lacks Sanford
Published: January 2020

Mutants of
Diplococcus pneumoniae
that lacked the two major deoxyribonucleases of the cell—one an endonuclease, the other an exonuclease preferentially active on native deoxyribonucleic acid (DNA)—were obtained. The development of a method for detecting mutant colonies, based on the binding of methyl green to DNA, facilitated isolation of the mutants. Neither enzyme was essential for growth of the cells, for repair of ultraviolet damage, or for any phase of DNA-mediated transformation. Residual deoxyribonuclease activity in the double mutant corresponded to an exonuclease, approximately one-fifth as active as the major exonuclease, that attacked native and denatured DNA equally well. This activity appeared to be associated with the DNA-polymerase enzyme. A mutant that apparently lacked a cell wall lytic enzyme was also fully transformable. A mutant strain that was four times more sensitive to ultraviolet light than the wild type also transformed normally. Recipient cells of this strain were deficient in the repair of ultraviolet-irradiated transforming DNA. Mutants were found which, unlike the wild type, integrated donor markers only with high efficiency, thereby indicating that a particular cellular component that is susceptible to loss by mutation, such as an enzyme, is responsible for low integration efficiency.
β-Galactosidase: Isolation of and Antibodies to Incomplete Chains
Authors: Berg Alan P. , Fowler Audree V. , Zabin Irving
Published: January 2020

A prematurely terminated polypeptide chain was purified to homogeneity from an
Escherichia coli
amber mutant strain containing the site of the mutation in the β-galactosidase structural gene. The polypeptide was highly active against anti-β-galactosidase, and had an amino acid composition similar to but not identical to that of β-galactosidase. The molecular weight of the reduced, carboxymethylated chain in 6
m
guanidine hydrochloride was found to be 89,000, in excellent agreement with the size predicted from the position of the mutation. This result adds further support to the conclusion that the gene specifies the structure of a single polypeptide chain. Antisera were prepared against partially purified preparations of this polypeptide and a similar one, of molecular weight about 100,000, produced by another amber mutant. These sera had lower titers towards β-galactosidase than anti-β-galactosidase. In the double-diffusion test, they reacted towards extracts of nonsense and deletion mutant strains in a pattern similar to that previously observed with anti-β-galactosidase. A sensitive immunological test for cross-reacting protein was devised based on the inhibition by β-galactosidase of the reaction between such protein and antibodies prepared against incomplete chains.
X-Ray Diffraction Studies of the Sulfur Globules Accumulated by
Chromatium
Species
Authors: Hageage G. J. , Eanes E. D. , Gherna R. L.
Published: January 2020

Isolated wet and dried sulfur globules, obtained by osmotic lysis of lysozyme-ethylenediaminetetraacetic acid prepared spheroplasts of
Chromatium okenii, C. weissei
, and
C. warmingii
, were studied by polarizing microscopy and X-ray diffraction. When viewed through crossed Nicol prisms, the sulfur globules, whether in the cell or isolated in a pure, wet state, had a characteristic maltese cross appearance. The observation that rotation of the mount did not change the orientation of the arms suggested a symmetrical radial arrangement of the birefringent units. X-ray diffraction patterns of freshly isolated, wet sulfur globules gave two broad and diffuse diffraction rings with maxima at 0.36 and 0.52 nm. This pattern closely resembled the diffraction pattern of liquid sulfur. When allowed to stand in the wet state, the sulfur globules eventually converted into crystalline orthorhombic sulfur after passing through an unstable crystalline phase not previously described by X-ray diffraction. Vacuum drying of the sulfur globules accelerated the change into crystalline orthorhombic sulfur.
Thymine and Thymidine Uptake by
Haemophilus influenzae
and the Labeling of Deoxyribonucleic Acid
Authors: Carmody Janice M. , Herriott Roger M.
Published: January 2020

The influence of ribo- and deoxyribonucleosides and ribo- and deoxyribonucleotides on the uptake of radiolabeled thymidine and thymine by
Haemophilus influenzae
during growth was investigated. A nucleoside-degrading enzyme similar to that reported in
Escherichia coli
was found to break down thymidine unless other nucleosides were present to divert its action. The presence of other nucleosides permitted a nearly quantitative uptake of even low levels of thymidine. This quantitative uptake of thymidine in the presence of an excess of other nucleosides suggests that the uptake mechanism for thymidine is specific in this organism. Under optimal conditions, as much as 50% of the deoxyribonucleic acid (DNA) thymine was derived from exogenous thymidine. Thymine was not taken up by
H. influenzae
but, in the presence of purine deoxynucleosides, labeled thymine entered the cells, presumably as thymidine. Ribonucleosides or ribonucleotides inhibited thymine conversion to thymidine, but, as noted above, they were degraded by a cellular enzyme. Thus, unless the ribonucleoside level was excessively high, a cell level of growth was reached at which the inhibiting ribonucleoside was broken down and labeled thymine appeared in the cells at an increasing rate. Twenty-five per cent of the DNA thymine of this organism was labeled with exogenous thymine. The information noted above serves as the basis for isotopically labeling the DNA.
Urea-Mercaptoethanol-Soluble Protein from Spores of
Bacillus thuringiensis
and Other Species
Authors: Somerville H. J. , Delafield F. P. , Rittenberg S. C.
Published: January 2020

Treatment with urea-mercaptoethanol of purified spores of
Bacillus thuringiensis
, other
Bacillus
species, and
Clostridium roseum
solubilizes a protein fraction between 5 and 12% of the dry weight of the spores. This fraction behaves identically to the crystal protein of
B. thuringiensis
on acrylamide-gel electrophoresis. The protein from all of the
Bacillus
species shows partial homology with crystal protein, using the Ouchterlony immunodiffusion technique. A further fraction, similar in amount, can be removed from spores of
B. thuringiensis
by the addition of sodium lauryl sulfate to the urea-mercaptoethanol. Spores of
B. thuringiensis
extracted in these ways show no difference when compared to untreated spores with respect to viability or resistance to heat and ultraviolet-irradiation. The extracted spores do show differences in their germination requirements and their susceptibility to phase-darkening by lysozyme. It is concluded that an urea-mercaptoethanol-soluble protein or class of protein is a widespread component of bacterial spores, possibly located in the spore coat, and that this protein may be related to the crystal protein of
B. thuringien
sis.
Interaction of Ribosomes and the Cell Envelope of
Escherichia coli
Mediated by Lysozyme
Authors: Patterson David , Weinstein Mark , Nixon Ralph , Gillespie David
Published: January 2020

Evidence is presented suggesting the existence of a natural ribosome-membrane complex. A reconstruction system is described wherein free ribosomes form a complex which appears to involve cell fragments. The reconstructed complex is similar in stability to the inferred natural complex. The reconstructed complex is generated by lysozyme, and it is concluded that at least part of the inferred natural complex is also generated by lysozyme. These results are discussed with reference to existing data concerning certain membrane-associated systems in bacteria.
Thiostrepton, an Inhibitor of 50
S
Ribosome Subunit Function
Authors: Weisblum B. , Demohn V.
Published: January 2020

Thiostrepton inhibits
14
C-leucine incorporation by intact cells of
Bacillus megaterium
as well as
14
C-phenylalanine incorporation by a poly U-directed extract of
Escherichia coli
. Extracts of
E. coli
which are pretreated by incubation with thiostrepton cannot be reactivated by dialysis to more than 5% of their former activity. The 50
S
ribosome subunit appears to be the site of thiostrepton action, since protein-synthesizing activity can be restored to dialyzed pretreated extracts by supplementation with 50
S
ribosome subunits but not with 30
S
ribosome subunits. This technique also provides a simple sensitive method for detection of the biological activity of very small amounts of 50
S
ribosome subunits.
Effect of Glycine on Thiazole Biosynthesis in
Escherichia coli
Authors: Iwashima Akio , Nose Yoshitsugu
Published: January 2020

Glycine was found to replace thiamine thiazole for the growth of the thiazoleless mutant of
Escherichia coli
; it also stimulated the production of thiamine thiazole by washed cell suspensions of the mutant.
Simple Selection for End-Product Inhibitor-Insensitive Mutants in Yeast
Authors: Bussey Howard
Published: January 2020

Trifluoroleucine-resistant yeast mutants with an end-product-insensitive α-isopropylmalate synthetase are dominant in diploids. This property provides a simple screen for their detection.
Generalized Transduction in
Corynebacterium renale
Authors: Hirai K. , Yanagawa R.
Published: January 2020

A phage, designated RP28, was obtained which carried out generalized transduction in
Corynebacterium renale
, and 11 different auxotrophic markers were all transduced.
Bacteriochlorophyll, Fatty-Acid, and Protein Synthesis in Relation to Thylakoid Formation in Mutant Strains of
Rhodospirillum rubrum
Authors: Oelze J. , Schroeder J. , Drews G.
Published: January 2020

Mutant strains of
Rhodospirillum rubrum
are isolated which are blocked in different stages of pigment synthesis. In these strains the morphogenesis of thylakoids and the pigment production are investigated. Concerning bacteriochlorophyll synthesis two groups of mutants are separable. The members of the first group synthesize bacteriochlorophyll. Some of these mutants excrete bacteriopheophytin. The strains of the second group are not able to synthesize bacteriochlorophyll. Members of both groups excrete bacteriochlorophyll precursors into the cultural medium. These pigments were identified by their spectral properties as Mg-2,4-divinyl-pheoporphyrin a
5
-monomethylester, pheophorbide a, and 2-devinyl-2-hydroxyethyl-pheophorbide a. Thylakoids are only formed by those strains which are able to synthesize bacteriochlorophyll. However, small amounts of bacteriochlorophyll can be produced without a concomitant thylakoid synthesis. The fatty-acid pattern in some mutants is modified quantitatively. However, the results do not indicate any correlation between disturbance of thylakoid morphogenesis and a deviation of fatty-acid composition. Fatty acids seem to have no special functions in thylakoid morphogenesis. The membranes of the mutants were isolated, split into protein subunits, and these were separated by disc electrophoresis. A characteristic protein pattern, first of all a high content of fraction E, is correlated with the ability to form thylakoids. In addition, all mutants which synthesize bacteriochlorophyll contain a fast-migrating membrane protein (zone G). The results suggest that the whole bacteriochlorophyll-protein complex is necessary for thylakoid formation.
α-3-Ketoglucosidase of
Agrobacterium tumefaciens
Authors: Hayano Koichi , Fukui Sakuzo
Published: January 2020

A 3-ketosucrose-degrading enzyme was purified 80-fold from the sonic extracts of
Agrobacterium tumefaciens
IAM 1525 grown on a sucrose-containing medium. The enzyme catalyzes hydrolysis of α-3-ketoglucosides such as 3-ketosucrose, 3-ketotrehalose, 3-ketomaltose, and 3-ketoglucose-1-phosphate but not of β-3-ketoglucosides, β-3-ketogalactosides, and other glycosides such as sucrose, trehalose, maltose, glucose-1-phosphate, cellobiose, lactose, or raffinose. From the strict substrate specificity of this enzyme, the name α-
d
-3-ketoglucoside 3-ketoglucohydrolase (trivial name, α-3-ketoglucosidase) was proposed.
K
m
values for 3-ketosucrose and 3-ketotrehalose were 3.9 × 10
−3
m
and 4.8 × 10
−3
m
, respectively. Optimum
p
H was 8.0 to 8.3. 3-Ketoglucose, a reaction product from α-3-ketoglucosides by the enzyme, behaved as a strong inhibitor. Physiological significance of this enzyme in the disaccharide metabolism of this bacterium was discussed.
Action of a Toxic Glycolipid of
Corynebacterium diphtheriae
on Mitochondrial Structure and Function
Authors: Kato Masahiko
Published: January 2020

The toxicity for mice of the cord factor of
Cornebacterium diphtheriae
, trehalose-6,6′-dicorynomycolate, was studied. The diphtherial cord factor showed a delayed lethal toxicity for mice; the median lethal dose was 120 μg. Mouse liver mitochondria were disrupted in vivo under the toxic action of the diphtherial cord factor into fragments deficient in both respiration and phosphorylation. The site of metabolic defect in the mitochondrial electron transport system was located at the region prior to the level of cytochrome
c
in the livers of cord factor-intoxicated mice. These effects of the diphtherial cord factor on the host-cell mitochondria were essentially similar to those of the cord factor of
Mycobacterium tuberculosis
, trehalose-6,6′-dimycolate.
Purification and Properties of the Constituents of the Nitrogenase Complex from
Clostridium pasteurianum
Authors: Vandecasteele Jean-Paul , Burris R. H.
Published: January 2020

A new procedure for a rapid and extensive purification of the FeMo protein and the Fe protein of the nitrogenase complex from
Clostridium pasteurianum
is described. Specific activities of 345 and 460 nmoles of N
2
reduced per mg of protein per min for the FeMo protein and for the Fe protein, respectively, have been obtained. Preparations of the FeMo protein contained 0.96 atom of molybdenum and 15 atoms of iron per molecule, whereas those of the Fe protein contained 2.86 atoms of iron per molecule. Experiments suggest that a definite association of two Fe proteins and one FeMo protein is functional in the active enzyme complex. No individual role could be ascribed to either of the two proteins, but the fact that hydrogenase inhibits N
2
fixation but not the reductant-dependent adenosine triphosphate hydrolysis supports the idea that there are two distinct sites on nitrogenase, one concerned with N
2
activation and the other with activated electron transport.
Role of Enzymes in Growth and Morphology of
Neurospora crassa
: Cell-Wall-Bound Enzymes and Their Possible Role in Branching
Authors: Mahadevan P. R. , Mahadkar U. R.
Published: January 2020

The cell wall of
Neurospora crassa
contains bound enzymes that can digest its structural polymers. These enzymes are not present at the same levels at all stages of growth. The levels of these autolytic enzymes vary and generally show some relationship to the process of branching. These enzymes were removed from the cell wall by β-mercaptoethanol extraction and were tested for activity against isolated cell wall fractions. Such studies, as well as autolytic studies, showed that enzymes acting on the protein portion of the cell wall (proteases) are more prominent than enzymes that act on the glucan portion (glucanases) of the cell wall. Comparative studies between the wild type and a spreading colonial mutant
spco-1
showed that earlier and higher frequency of branching in
spco-1
was correlated with a greater amount of these enzymes bound to the cell walls. It is concluded from these observations that autolytic enzymes acting on the protein and glucan portion of the cell walls occur as wall-bound and participate in the process of branching in
Neurospora
.
Biochemical Characterization of Sulfur Assimilation by
Salmonella pullorum
Authors: Kline Bruce C. , Schoenhard Delbert E.
Published: January 2020

The biochemical basis for a cysteine requirement in
Salmonella pullorum
strain MS35 is presented. Before determining the missing biochemical functions, it was established that the assimilatory sulfate-reducing pathway for this species is an inorganic one in which 3′-phosphoadenylylsulfate (PAPS), sulfite, and sulfide are intermediates. A requirement for 2′- and 3′-adenosine monophosphate was found for in vitro synthesis of PAPS, possibly because 2′- and 3′-adenosine monophosphate inhibits endogenous nucleases that destroy PAPS. The cysteine requirement of strain MS35 was attributed to a defect at 37 C in sulfate permeation and temperature sensitivity in sulfite reduction. At 25 C, sulfite was metabolized to sulfide. A novel property of sulfate-utilizing revertants was their unselected ability to assimilate thiosulfate sulfur at 25 C but not at 37 C.
Isolation and Partial Characterization of
Escherichia coli
Mutants with Altered Glycyl Transfer Ribonucleic Acid Synthetases
Authors: Folk William R. , Berg Paul
Published: January 2020

Isolates with mutations in
glyS
, the structural gene for glycyl-transfer ribonucleic acid (tRNA) synthetase (GRS) in
Escherichia coli
, are frequently found among glycine auxotrophs. Extracts of
glyS
mutants have altered GRS activities. The mutants grow with normal growth rates in minimal media when high levels of glycine are provided. No other metabolite of a variety tested is capable of restoring normal growth. The
glyS
mutants fail to make ribonucleic acid (RNA) when depleted of exogenous glycine in strains which are
RC
str
but do so when the cells are
RC
rel
. In contrast, biosynthetic mutants which are unable to synthesize glycine (
glyA
mutants) do not make RNA when deprived of glycine even if they are
RC
rel
; in this case, RNA is synthesized upon glycine deprivation only when the nucleic acid precursors made from glycine are provided in the medium. The level of serine transhydroxymethylase is unaltered in extracts of any of the
glyS
mutants, even though the level of charged tRNA
Gly
is at least 20-fold lower than that found in a prototrophic parent; this indicates that, if there is control over the synthesis of serine transhydroxymethylase, it is not modified by reduced levels of charging of the major species of tRNA
Gly
.
Effect of Biotin on Fatty Acids and Phospholipids of Biotin-Sensitive Strains of
Rhizobium japonicum
Authors: Bunn C. R. , McNeill J. J. , Elkan G. H.
Published: January 2020

The effect of biotin on fatty acids and intact lipids was studied by comparing a biotin-requiring, a biotin-inhibited, and a biotin-indifferent strain of
Rhizobium japonicum
. These organisms were grown in a defined medium with added levels of 0, 0.3, and 0.5 μg of biotin per liter, and were analyzed for fatty acids and lipid components. Myristic, palmitic, and octadecenoic acids were found to be the major fatty acids in these strains. The indifferent strain also contained large amounts of C
19
cyclopropane acid and small amounts of a C
17
cyclopropane acid. Several unidentified acids were present in the other two strains. The percentages of fatty acids showed statistically significant changes corresponding with changes in level of biotin in the medium. When biotin concentration was increased in the medium, the C
18
monoenoic acids of the biotin-requiring strain increased significantly, and those of the biotin-inhibited and biotin-indifferent strains decreased significantly. Palmitic acid showed a statistically significant increase in the indifferent strain with increasing biotin concentration. The principal intact lipid components in these strains are phospholipids. The major phospholipids are phosphatidylserine, phosphatidylcholine, phosphatitidylethanolamine, and cardiolipin. These phospholipids were not affected by biotin level and were independent of medium composition.
d
-Glucaric Acid and Galactaric Acid Catabolism by
Agrobacterium tumefaciens
Authors: Chang Yung Feng , Feingold David Sidney
Published: January 2020

Cell-free extract (crude extract) of
Agrobacterium tumefaciens
grown on
d
-glucuronate or
d
-glucarate converts
d
-glucarate and galactarate to a mixture of 2-keto-3-deoxy- and 4-deoxy-5-keto-
d
-glucarate. These compounds are then converted by partially purified crude extract to an intermediate tentatively identified as 2,5-diketoadipate. The same enzyme preparation further decarboxylates this intermediate to α-ketoglutarate semialdehyde, which is subsequently oxidized in a nicotinamide adenine dinucleotide-dependent reaction to α-ketoglutaric acid. Since
A. tumefaciens
converts
d
-glucuronic acid to
d
-glucarate, a pathway from
d
-glucuronate to α-ketoglutarate in
A. tumefaciens
was determined.
Relationship Between Phospholipid Biosynthesis and the Efficiency of the Arsenate Transport System in Yeasts
Authors: Cerbón Jorge
Published: January 2020

In studying the possibility that phosphoinositides which formed complexes with arsenic were involved in the arsenate transport system of yeasts, a comparative study of the phospholipid composition and metabolism was carried out both in
Saccharomyces carslbergensis
and in its arsenate-adapted variant, which showed a deficient inflow of arsenate. It was found that the lipid composition of the two organisms was quite similar, the main classes of phospholipids being phosphatidylcholine, phosphatidylethanolamine, and phosphoinositides. The only difference was a 1.5- to 2-fold increase in the proportion of inositides in the arsenate-adapted cells. When the transport of arsenate became inactivated in the nonadapted yeasts after a 30- to 60-min exposure to 10
−2
m
arsenate, an increment of inositides of 29 to 50% over the original level was also detected. A study of the incorporation of radioactivity from uniformly labeled
14
C-maltose and from
32
P-orthophosphate (
32
P
i
) demonstrated a decreased rate of lipid biosynthesis in the arsenate-adapted cells as compared to the normal nonadapted ones. The turnover of the phosphate in phospholipids demonstrated no turnover in phosphatidylcholine and phosphatidylethanolamine, and a slow turnover in phosphoinositides. It could be inferred that a normal rate of phospholipid (phosphoinositides) biosynthesis is necessary to have a normal arsenate uptake and that inositide accumulation impairs both the mechanism responsible for the uptake and accumulation of arsenate and the rate of lipid biosynthesis. No differences were found in the deoxyribonucleic acid or protein content of the two types of cells. Also, the arsenate-adapted cells, once freed of external arsenate, showed an increased uptake of
32
P
i
from low external concentrations of phosphate (10
−6
to 10
−8
m
, 10-fold over that observed in AsS cells). These results are indicative of independent behavior in phosphate and arsenate transport systems.
Endo-
N
-acetyl-glucosaminidase from
Clostridium perfringens
, Lytic for Cell Wall Murein of Gram-Negative Bacteria
Authors: Martin H. H. , Kemper Stefanie
Published: January 2020

An endo-
N
-acetyl-glucosaminidase which degrades the murein (peptidoglycan) sacculi of the cell walls of
Escherichia coli
and
Spirillum serpens
, but not those of
Micrococcus lysodeikticus
and
Sarcina lutea
, is present as a contaminant in a “phospholipase C” from
Clostridium perfringens
. The specificity of enzyme action was elucidated by reduction of liberated glycosidic groups with NaBH
4
and identification of glucosaminol as the reduction product. This finding contradicts previous reports associating cell wall breakdown with specific phospholipase action.
Anaerobic Degradation of the Benzene Nucleus by a Facultatively Anaerobic Microorganism
Authors: Taylor Barrie F. , Campbell William L. , Chinoy Ira
Published: January 2020

A bacterium was isolated by elective culture with
p
-hydroxybenzoate as substrate and nitrate as electron acceptor. It grew either aerobically or anaerobically, by nitrate respiration, on a range of aromatic compounds. The organism was identified as a pseudomonad and was given the trivial name
Pseudomonas
PN-1. Benzoate and
p
-hydroxybenzoate were metabolized aerobically via protocatechuate, followed by
meta
cleavage catalyzed by protocatechuic acid-4,5-oxygenase, to yield α-hydroxy-γ-carboxymuconic semialdehyde.
Pseudomonas
PN-1 grew rapidly on
p
-hydroxybenzoate under strictly anaerobic conditions, provided nitrate was present, even though protocatechuic acid-4,5-oxygenase was repressed. Suspensions of cells grown anaerobically on
p
-hydroxybenzoate oxidized benzoate with nitrate and produced 4 to 5 μmoles of CO
2
per μmole of benzoate added; these cells did not oxidize benzoate aerobically. The patterns of the oxidation of aromatic substrates with oxygen or nitrate by cells grown aerobically or anaerobically on different aromatic compounds indicated that benzoate rather than protocatechuate was a key intermediate in the early stages of anaerobic metabolism. It was concluded that the pathway for the anaerobic breakdown of the aromatic ring is different and quite distinct from the aerobic pathway. Mechanisms for the anaerobic degradation of the benzene nucleus by
Pseudomonas
PN-1 are discussed.
Role of Homocysteine Synthetase in an Alternate Route for Methionine Biosynthesis in
Saccharomyces cerevisiae
Authors: Cherest H. , Talbot G. , de Robichon-Szulmajster H.
Published: January 2020

In vivo studies have shown that, in the absence of homoserine-
O
-transacetylase activity (locus met
2
), the C
4
-carbon moiety of ethionine is utilized (provided the ethionine resistance gene eth-2r is present) by methionine auxotrophs, except for met
8
mutants (homocysteine synthetase-deficient). Concomitant utilization of sulfur and methyl group from methylmercaptan or S-methylcysteine has been demonstrated. In the absence of added methylated intermediates, the methyl group of methionine formed from ethionine is derived from serine. In vitro studies with crude extracts of
Saccharomyces cerevisiae
have demonstrated that this synthesis of methionine occurs by the following reactions: CH
3
-SH + ethionine ⇌ methionine + C
2
H
5
SH and S-methylcysteine + ethionine ⇌ methionine + S-ethylcysteine. In the forward direction, the second product of the second reaction was shown to be S-ethylcysteine; this reaction has also been found reversible, leading to ethionine formation. Genetic and kinetic data have shown that homocysteine synthetase catalyzes these two reactions, at 0.3% of the rate it catalyzes direct homocysteine synthesis:
O
-Ac-homoserine + Na
2
S → homocysteine + acetate. The three reactions are lost together in a met
8
mutant and are recovered to the same extent in spontaneous prototrophic revertants from this strain. Methionine-mediated regulation of enzyme synthesis affects the three activities and is modified to the same extent by the presence of the recessive allele (eth-2r) of the regulatory gene eth-2. Affinities of the enzyme for substrates of both types of reactions are of the same order of magnitude. Moreover, ethionine, the substrate of the second reaction, inhibits the third reaction, whereas
O
-acetyl-homoserine, the substrate of the third reaction, inhibits the second reaction. An enzymatic cleavage of S-methylcysteine, leading to methylmercaptan production, has been shown to occur in crude yeast extracts. It is concluded that the enzyme homocysteine synthetase participates in the two alternate pathways leading to methionine biosynthesis in
S. cerevisiae
, one involving
O
-acetyl-homoserine and H
2
S, the other involving the 4-carbon chain of ethionine and a mercaptyl donor. Participation of the two types of reactions catalyzed by homocysteine synthetase, in in vivo methionine synthesis, has been shown to occur in a met
2
partial revertant.
Amino Acid Control over Deoxyribonucleic Acid Synthesis inEscherichia coliInfected With T-Even Bacteriophage
Authors: Donini Pierluigi
Published: January 2020

Starvation for a required amino acid of normal or RCstrEscherichia coliinfected with T-even phages arrests further synthesis of phage deoxyribonucleic acid (DNA). This amino acid control over phage DNA synthesis does not occur in RCrelE. colimutants. Heat inactivation of a temperature-sensitive aminoacyl-transfer ribonucleic acid (RNA) synthetase similarly causes an arrest of phage DNA synthesis in infected cells of RCstrphenotype but not in cells of RCrelphenotype. Inhibition of phage DNA synthesis in amino acid-starved RCstrhost cells can be reversed by addition of chloramphenicol to the culture. Thus, the general features of amino acid control over T-even phage DNA synthesis are entirely analogous to those known for amino acid control over net RNA synthesis of uninfected bacteria. This analogy shows that the bacterialrellocus controls a wider range of macromolecular syntheses than had been previously thought.
Role of Pili in Bacterial Conjugation
Authors: Ou Jonathan T. , Anderson Thomas F.
Published: January 2020

We describe techniques for isolating individual pairs of mating
Escherichia coli
and observing them under the light microscope. Some pairs achieved close cell-to-cell contact, whereas others remained loosely connected by invisible connections which may be F pili. After 30 min of mating, the pairs were separated and allowed to grow into clones. That many exconjugants derived from “loose”-mating pairs produced recombinants suggests that F pili are involved in the transfer of genetic material. The frequency of formation of recombinants from “close”-mating pairs, however, was significantly higher than that from loose-mating pairs, indicating that a close cell-to-cell contact facilitates chromosome transfer. Death rates of exconjugants from close pairs were also higher than those from loose pairs. Hfr × F
−
matings produced higher death rates than F
+
× F
−
matings. Male cells were found capable of transferring genetic markers to two F
−
cells simultaneously. We conclude that F pili play at least three roles in mating: (i) they initiate contacts between mating pairs; (ii) they facilitate the transfer of genetic material; and (iii) they draw mating cells into a close contact which increases the fertility of the union.
Effect of Manganese and Zinc Ions on the Growth of
Rhizobium
Authors: Wilson D. O. , Reisenauer H. M.
Published: January 2020

Five strains, representing four species of
Rhizobium
, were grown in specially purified synthetic culture solutions with manganese or zinc ion concentrations ranging from 0 to 10
−5
m
. Omission of Mn
2+
restricted growth to 0.4 to 10% of that of controls, depending on the species. Growth was generally maximum with 10
−6
m
Mn
2+
and nearly so with 10
−5
m
. Omission of Zn
2+
restricted growth to 1 to 20% of that of controls. Growth was generally maximum with 10
−7
m
Zn
2+
. The 10
−5
m
level of Zn
2+
was toxic to a variable degree to all species, suppressing the growth of one strain of
R. meliloti
to 49% of that of controls, and of
R. phaseoli
to only 0.4% of that of controls. A Mn
2+
× Zn
2+
interaction was also obtained as evidenced by a higher apparent Zn
2+
requirement with 10
−7
m
Mn
2+
than with 10
−6
m
Mn
2+
.
Composition and Properties of a Group A Streptococcal Teichoic Acid
Authors: Matsuno Takashi , Slade Hutton D.
Published: January 2020

Teichoic acid-like material extracted by cold trichloroacetic acid from lyophilized whole cells of streptococci from groups A,D,E,O, and T was shown to give a positive precipitin reaction with group antisera. Similar material from cells of groups B,C,F,G,H,K,L,M,N,P,Q,R, and S did not give a positive reaction with group antisera. The group A material also reacted with anti-E serum; however, the opposite did not occur. A similar result was also obtained on the group T material and anti-O serum. The group A teichoic acid was purified by Sephadex column chromatography, and was shown to be free of cell wall peptidoglycan and polysaccharide, and ribitol teichoic acid. It was composed of glycerol, phosphate, alanine, and glucosamine. Alkaline hydrolysis showed the presence of ester-linked alanine and glucosaminylglycerol. Phosphorus was released from ester linkage by alkaline phosphatase.
N
-acetylglucosamine produced a 72% inhibition of the precipitin test at a level of 10 μmoles, and
d
-alanine methyl ester was significantly stronger than the
l
-alanine ester. A single precipitin band was seen with group A serum. The data indicate that teichoic acid of group A streptococci is a polymer composed of glycerol phosphate and containing
N
-acetylglucosamine and alanine. Antisera to these streptococci contain antibodies specific for the alanine and the glucosamine linkages. The use of serum containing antibodies to alanine-polyglycerophosphate shows that the occurrence of this type of teichoic acid is widespread among the streptococci.
Transport and Retention of K
+
and Other Metabolites in a Marine Pseudomonad and Their Relation to the Mechanism of Optical Effects
Authors: Matula Tibor I. , Srivastava Vinod S. , Wong Paul , MacLeod Robert A.
Published: January 2020

Suspensions of cells of a marine pseudomonad washed with 0.05
m
MgSO
4
showed an immediate increase in optical density (first-phase optical change) when the salt concentration of the suspending medium was increased; a subsequent slow decrease in optical density (second-phase optical change) occurred if K
+
was present. The rate of the second-phase change was similar to the rate of uptake of
42
K
+
by the cells. Glutamate increased the rate and extent of the second-phase change and produced a parallel increase in the rate and extent of uptake of
42
K
+
. Citrate increased the extent of the second-phase change in cells adapted to oxidize citrate but not in unadapted cells. Adapted, but not unadapted, cells accumulated
14
C-citrate. The nonmetabolizable α-aminoisobutyric acid (AIB) also increased the extent of the second-phase change under conditions leading to the uptake of
14
C-AIB by the cells. Cells maintained in a salt solution optimal for the retention of intracellular solutes were found to contain 0.184
m
K
+
. In the same salt solution, cells preloaded with
42
K
+
retained the isotope, but they lost it rapidly when suspended in 0.05
m
MgSO
4
. The second-phase changes can be accounted for by the energy-dependent accumulation in an osmotically active form of K
+
and other metabolites by cells depleted of intracellular solutes.
Regulation of Proline Degradation inSalmonella typhimurium
Authors: Dendinger Susan , Brill Winston J.
Published: January 2020

The pathway for proline degradation inSalmonella typhimuriumappears to be identical to that found inEscherichia coliandBacillus subtilis. Δ1-Pyrroline-5-carboxylic acid (P5C) is an intermediate in the pathway; its formation consumes molecular oxygen. Assays were devised for proline oxidase and the nicotinamide adenine dinucleotide phosphate-specific P5C dehydrogenase activities. Both proline-degrading enzymes, proline oxidase and P5C dehydrogenase, are induced by proline and are subject to catabolite repression. Three types of mutants were isolated in which both enzymes are affected: constitutive mutants, mutants with reduced levels of enzyme activity, and mutants unable to produce either enzyme. Most of the mutants isolated for their lack of P5C dehydrogenase activity have a reduced level of proline oxidase activity. All the mutations are cotransducible. A genetic map of some of the mutations is presented. The actual effector of the pathway appears to be proline.
Propagation and Growth Cycle of
Rickettsia quintana
in a New Liquid Medium
Authors: Mason Richard A.
Published: January 2020

The growth cycle of
Rickettsia quintana
was studied for the first time in liquid culture. Growth of the microorganism in a transparent broth medium was made possible by the finding that fetal calf serum (FCS), but not calf serum (CS), satisfied the requirement of
R. quintana
(Fuller strain) for red blood cell lysate. The three constituents of the medium, other than FCS, were autoclavable. The growth cycle was characterized by a lag phase of approximately 24 hr, an exponential growth phase of 72 hr, and a doubling time of approximately 4.5 hr. In FCS medium, titers increased 10
5
-fold over starting titers and reached a peak after 5 days of greater than 10
8
colony-forming-units (CFU)/ml. Optical density readings at 520 nm (OD
520
) served as useful estimates of the titers only during the last 30 hr of exponential growth. Before this time, titers were below 3 × 10
7
CFU/ml and could not be detected at OD
520
. The growth-promoting activity of FCS appeared to be a normal serum component widely distributed among fetal calves. FCS from five commercial suppliers supported growth of
R. quintana
. The active factor(s) was: (i) non-dialyzable, (ii) resistant to heating at 56 C for 30 min, and (iii) partially inactivated at 100 C in 2 min and completely lost at 100 C in 10 min. The results emphasize the presence of erythrocyte and serum factors other than hemoglobin which stimulate the growth of
R. quintana
.
Early Changes in the Ultrastructure of
Streptococcus faecalis
After Amino Acid Starvation
Authors: Higgins M. L. , Shockman G. D.
Published: January 2020

Thin sections of
Streptococcus faecalis
(ATCC 9790) starved of one essential amino acid (threonine or valine) initially show rapid increases in (i) cell wall thickness, (ii) the apparent size of the central nucleoid region, and (iii) mesosomal membranes. The most rapid increases in all three variables occurred during the first 1 to 2 hr of starvation. After this initial period, the rates progressively decreased over the 20-hr observation period. During threonine starvation, the mesosomal membrane that accumulated in the first hour was subsequently degraded and reached a level similar to that found in exponential-phase cells after 20 hr. With valine starvation, mesosomal membrane continued to slowly accumulate over the entire 20-hr observation period. The mesosomes of the starved cells retained the same “stalked-bag” morphology of those in exponential-phase cells. These cytological observations agree with previously published biochemical data on membrane lipid and wall content after starvation.
Metabolism of Phospholipid 2-Linked Fatty Acids During the Release of Membrane Fragments from
Haemophilus parainfluenzae
by Ethylenediaminetetraacetic Acid-Tris(hydroxymethyl)-aminomethane
Authors: Tucker Anne N. , White David C.
Published: January 2020

Membrane fragments containing diacyl phospholipids were released from viable cells of
Haemophilus parainfluenzae
during incubation in ethylenediaminetetraacetic acid (EDTA)- tris(hydroxymethyl)aminomethane (Tris) buffer. The phospholipids located in the part of the membrane that was released during the EDTA-Tris treatment had markedly different proportions of fatty acids than the lipids remaining in the cell residue. Very little metabolism of the 1-linked fatty acid occurred. After a short pulse with
14
C, the specific activity of the 1-linked fatty acid was lower in the phospholipids released than in the phospholipids of the residue, indicating an earlier time of synthesis of those lipids released in the membrane fragments. During the EDTA-Tris treatment, the 2-linked fatty acid was metabolized. This metabolism may have involved phospholipase
A
2
which stimulates the synthesis of fatty acids and the transfer of acyl groups to the lysophospholipid.
Developmental Regulation of α-Mannosidase in
Dictyostelium discoideum
Authors: Loomis William F.
Published: January 2020

The specific activity of α-mannosidase (EC 3.2.1.24) has been found to increase more than a thousandfold during development of the cellular slime mold,
Dictyostelium discoideum
. The enzyme accumulates in both spore and stalk cells. Studies with preferential inhibitors of macromolecular synthesis indicate that accumulation of α-mannosidase requires concomitant protein synthesis and prior ribonucleic acid synthesis. Control of the period of synthesis by the overall developmental program is demonstrated in two temporally deranged morphological mutants. α-Mannosidase is found in lysosomes of
D. discoideum
in association with other acid hydrolases which may be involved in metabolism of extracellular polysaccharide.