Search PubMed⌕ Search

Biomedical subjects

S Razin

Publications and source records attributed to S Razin.

At least 109 records · Page 6Linked to original sources
PubMed1973

Isolation, ultrastructure and antigenicity of Mycoplasma gallisepticum membranes.

The cell membrane of Mycoplasma gallisepticum was isolated by lysing the cells with digitonin. Chemical and density-gradient analyses and electron microscopy showed the isolated membranes to be relatively free of cytoplasmic contaminants. The density of the membranes exceeded that of other mycoplasma membranes, indicating a higher protein content. Small vesicular extensions seen in the sectioned membranes were interpreted as empty blebs.The isolated membranes, but not the cytoplasmic fraction, elicited in chickens the production of growth-inhibiting, agglutinating and haemagglutination-inhibition antibodies to M. gallisepticum in titres resembling those obtained by injection of whole cells. The peak of the serological response varied with the serological test employed. The rapid slide-agglutination test became positive as early as 3 days after the first injection of only 50 mug. of membrane protein. The haemagglutination-inhibition antibody titre reached its peak at about 10 days after the first injection, while that of the growth-inhibiting antibodies was reached only at about 25 days. The addition of adjuvant to the membrane antigen did not improve the production of the growth-inhibiting antibodies in chickens, but it produced some improvement in rabbits. Our results support the thesis that the chief immunogens of M. gallisepticum reside in the cell membrane of this organism.

Agglutination Tests↗
PubMed1973

Immunoelectrophoretic analysis of Mycoplasma mycoides var. mycoides.

Acrylamide gel electrophoresis was used to show the similarities and differences in the membrane proteins of two vaccine and two virulent strains of Mycoplasma mycoides var. mycoides. Immunoelectrophoretic (IEP) analysis was also used to partially characterize the associated antigens. Antibody spectra to the antigens of M. mycoides differ in rabbit, pig, and cattle sera. Rabbits produce better precipitating antibody against the anodic migrating protein mycoplasma antigens than cattle and pigs as seen in IEP. However, rabbit anti-M. mycoides serum did not show precipitating antibody against the heat-stable carbohydrate antigen. As judged by IEP, the major carbohydrate antigen extracted from the media, or boiled whole organism, is similar to that present in the sera-infected cattle and knee joints of calves. This carbohydrate antigen has a cathodic migration in IEP at pH 8.6. Periodate oxidation, classically used to destroy carbohydrate, also destroys most of the protein antigens. Heating the antigens to 56 C for 10 min destroys many of the noncarbohydrate antigens and 100 C eliminates all but the carbohydrate antigen. Extraction of M. mycoides with chloroform-methanol, phenol, ethanol, or ethanol-acetone reduced or eliminated most of the protein antigens. Some of the isolated antigenic fractions of M. mycoides were tested to determine their activity in the diagnostic complement fixation test for contagious bovine pleuropneumonia and their inhibitory effect in this test by using bovine anti-M. mycoides antisera having precipitating antibody and circulating antigen. The complement fixation antigen is not the galactan, cannot be extracted by chloroform-methanol, but is stable to boiling at 100 C and may be extracted by phenol and partially precipitated by ethanol-acetone.

Animals↗
PubMed1973

Distribution of a phosphoenolypyruvate-dependent sugar phosphotransferase system in mycoplasms.

A survey of 10 mycoplasma strains has shown that their capacity to accumulate radioactivity from alpha-methyl-d-glucopyranoside depends on the activity of a phosphoenolpyruvate-dependent phosphotransferase system (PTS), and that this system endows the organisms with a high affinity for glucose as a fermentation substrate. PTS activity was found in Mycoplasma gallisepticum, M. mycoides var. mycoides, and M. mycoides var. capri, but in none of the fermentative Acholeplasma strains nor in some of the nonfermentative Mycoplasma species. Partial characterization of the PTS of M. mycoides var. capri has shown that, like the PTS of Escherichia coli and Staphylococcus aureus, it is strictly dependent on phosphoenolpyruvate as a phosphoryl donor and on componenets of both the cytoplasm and the membrane.

Carbon Isotopes↗
PubMed1973

Membrane lipids of Mycoplasma hominis.

Essentially all of the lipids of Mycoplasma hominis (200 mug/mg of cell protein) were found to be located in the cell membrane. Over one-half were neutral lipids incorporated from the growth medium and consisting of 43% free cholesterol, 19% esterified cholesterol, 23% triglycerides, 10% free fatty acids, and small amounts of di- and monoglycerides. The polar lipids accounting for about 40% of the total were synthesized by the organisms. Phosphatidylglycerol was the predominant lipid of this fraction. The minor components, tentatively identified as lysophosphatidylglycerol and phosphatidic acid, seem to represent breakdown products of phosphatidylglycerol. No glycolipids were detected. Being unable to synthesize long-chain fatty acids, M. hominis utilized the fatty acids of the growth medium for polar lipid synthesis, preferentially the saturated ones, so that the polar lipids had highly saturated hydrocarbon chains. It is proposed that the large take up of unsaturated neutral lipids and cholesterol from the medium offsets the marked condensing effect of the saturated polar lipids, although electron paramagnetic resonance spectrometry of spin-labeled fatty acids incorporated into the M. hominis membrane indicated that the lipid region is still more rigid than that of the Acholeplasma laidlawii membrane.

Acholeplasma laidlawii↗
PubMed1973

Acyl carrier protein in mycoplasmas.

Acyl carrier protein (ACP) activity was determined by the malonyl-coenzyme A-CO(2) exchange reaction. It was highest in Acholeplasma laidlawii, lower in A. granularum, and lowest in A. axanthum. The sterol-requiring Mycoplasma species examined showed little or negligible ACP activity. A. laidlawii was capable of utilizing pantetheine or coenzyme A but not beta-alanine as precursor for ACP synthesis. Its ACP could thus be labeled by growing the organisms with radioactive coenzyme A. The ACP of A. laidlawii appears to be a soluble cytoplasmic protein, which could be purified about 40-fold by treatment of the cytoplasmic fluid with streptomycin sulfate and chromatography of the supernatant fluid on a Biogel P-10 column. Its molecular weight, determined by polyacrylamide gel electrophoresis, is low (about 10,900) resembling that of Escherichia coli, but it is much more sensitive to heat.

Acetates↗
PubMed1973

Divalent cations in native and reaggregated mycoplasma membranes.

The Mg(2+) content of membranes of several Mycoplasma and Acholeplasma species varied between 0.88 and 1.98 mug of Mg(2+) per mg of protein, depending on the species and on growth conditions. Ca(2+) could be detected only when it was added to the growth medium. The Mg(2+) content of isolated A. laidlawii membranes could be increased almost threefold by dialysis against 20 mm Mg(2+), whereas aggregated A. laidlawii membranes contained about six to eight times more Mg(2+) per mg of protein than the native membranes. This was taken to indicate that the molecular organization of the lipid and protein in the reaggregated membranes differs from that of the native membranes. Between 60 and 83% of the Mg(2+) in native and reaggregated A. laidlawii membranes was associated with the lipid fraction extracted with chloroform-methanol. The removal of over 80% of membrane protein by Pronase digestion did not release any significant amount of Mg(2+). Hence, most of the divalent cation appears to be bound to membrane lipids, most probably to phospholipids. Ethylenediaminetetraacetic acid released the bulk of Mg(2+) bound to the native and reaggregated A. laidlawii membranes, except for about 0.5 mug of Mg(2+) per mg of protein which was too tightly bound. Hence, a small but fairly constant amount of Mg(2+) is unavailable for chelation.

Acholeplasma laidlawii↗
PubMed1973

Isolation, chemical composition, and ultrastructural features of the cell membrane of the mycoplasma-like organism Spiroplasma citri.

Thin sections of Spiroplasma citri, a mycoplasma-like organism isolated from citrus infected with "Stubborn" disease, showed the organisms to be limited by a single trilaminar plasma membrane. An additional outer layer could, however, be frequently seen in freeze-etched preparations of unwashed cells. The organisms were found to be extremely sensitive to lysis by osmotic shock. The cell membrane of S. citri isolated in this way resembled that of mycoplasmas in ultrastructure and gross chemical composition. The isolated membranes showed the characteristic trilaminar shape in section and the typical particle-studded fracture faces in freeze-etched preparations. Protein and lipid formed over 80% of the total dry weight of the membrane, which had a density of ~1.180 g/cm(3). Cholesterol constituted over 20% of the total membrane lipid. Phosphatidyl-glycerol, synthesized by the organisms, was the major phospholipid. Significant amounts of hexosamine (15 to 35 mug/mg of membrane protein) could be found in the membrane preparations. Our results support the thesis that S. citri does not possess a cell wall, either of the gram-positive or the gram-negative type, though it may be coated by some other type of an envelope or by a slime layer, at least temporarily.

Bacterial Proteins↗
PubMed1972

Isolation of mycoplasma membranes by digitonin.

The cell membrane of Mycoplasma hominis was isolated by lysing the cells with digitonin. Electron microscopy and chemical, density gradient, and electrophoretic analyses of the membrane proteins showed the membranes so obtained, like those isolated by osmotic lysis, to be relatively free of cytoplasmic contaminants. Sensitivity to digitonin lysis depended on temperature but was not affected by Mg(2+) ions and was only slightly affected by the age of the culture. Accordingly, it seems that digitonin may be used for the isolation of cell membranes from sterol-requiring mycoplasmas that tend to be fairly resistant to osmotic lysis.

Bacterial Proteins↗
PubMed1971

Production and Properties of Antisera to Membrane Glycolipids of Mycoplasma pneumoniae.

The glycolipid haptens of Mycoplasma pneumoniae became immunogenic when bound to membrane proteins of Acholeplasma laidlawii by reaggregation. This process consisted of the solubilization of lipid-depleted A. laidlawii membranes and M. pneumoniae glycolipids in 20 mm sodium dodecyl sulfate and dialysis of the mixed solutions against 20 mm Mg(2+). The antibodies produced in rabbits to the reaggregated glycolipids inhibited the metabolism of M. pneumoniae, fixed complement with M. pneumoniae glycolipids or whole cells, precipitated M. pneumoniae glycolipids, and agglutinated M. pneumoniae cells. All these antibody activities could be blocked or absorbed by the purified glycolipids but not by a series of carbohydrates containing glucose and galactose. It was concluded that the antiserum to the reaggregated glycolipids may be regarded as a specific serum to membrane glycolipids of M. pneumoniae, since the antibodies to A. laidlawii membrane proteins, present in this serum, did not react with the glycolipids or with any other cell component of M. pneumoniae.

Journal Article↗