Composition of lipids of Actinomyces olivaceus--synthesis of vitamin B 12]

Total cellular lipids of the synthetic of vitamin B12 Act. olivaceus involve predominantly phospholipids (about 70%). Lipid phosphates consist of phosphatidyl ethanol amine and phosphatidyl-2,3-butandiol (over 40 and 30%, respectively) and lower quantities of phosphatidyl inositol olmonomanoside and cardiolipin. The neutral fraction includes the predominating fraction of triglycerides (over 20%) as well as mono- and diglycerides, free fatty acids, hydrocarbons and three fractions similar to waxes, sterines and sterine esters in their Rf values.     

Structural organization of the phospholipid component of Streptomyces hygroscopicus cell membranes as determined from neutron diffraction data

The nanoparameters of an actinobacterial membrane have been estimated by neutron diffraction on multilamellar lipid membranes. The lamellar repeat distance in a partly hydrated membrane prepared with the phospholipid fraction from Streptomyces hygroscopicus is 85.8 ± 0.5°C and decreases to 83.5 ± 0.5 0°C. Some lipids are not incorporated into the bilayer and form a liquid phase of micelles 54.2 ± 0.2     

Electron microscopic analysis of protoplast fusion in Streptomyces hygroscopicus and consideration on structural alterations in fusing membranes

Protoplasts of Streptomyces hygroscopicus were treated with polyethylene glycol and prepared for electron microscopic investigation as ultrathin sections. About 5% binary fusion products and 0.9% multicellular fusion products have been obtained in the sections. Three main types may be differentiated among binary fusion products, characterized by a successive loss of the bispherical shape and of continuous membrane structures in fusion zones.Analysing the membrane alterations a contact zone characterized by intact cytoplasmic membranes in both protoplasts, a fusion zone with a trilaminar fusion membrane of about 13–17 nm in thickness, and a fusion zone without continuous membrane structure can be distinguished. The different fusion areas are considered as stages in the fusion process. The data will be discussed in conjunction with a model for membrane alterations during fusion at the molecular level.     

Comparative Pathogenicity of Actinomyces naeslundii and Actinomyces israelii

Typical actinomycosis has been produced in mice following single intraperitoneal injections of saline suspensions of Actinomyces israelii and A. naeslundii. A. israelii produced infections in 95.8% of the animals inoculated. A. naeslundii, generally considered to be a saprophytic organism, produced lesions in 89.7% of the inoculated animals. The finding that A. naeslundii produced lesions in mice similar to those produced by A. israelii suggests that A. naeslundii has similar pathogenic potential for man. The isolation of A. naeslundii from suppurative lesions of man also supports this conclusion.     

Composition and enzyme activities of Spiroplasma citri membranes.

Spiroplasma citri was cultured in three different media that supplied cholesterol and fatty acids from: (i) horse serum, (ii) pleuropneumonia-like organism (PPLO) serum fraction, or (iii) bovine serum albumin-fatty acid-cholesterol. The ability of PPLO serum fraction to support growth varied by lot number. Neither PPLO serum fraction nor the bovine serum albumin medium supported growth as well as the horse serum medium. Analysis of cholesterol, lipid phosphorus, and membrane protein showed the horse serum- and PPLO-grown cells to be indistinguishable, but the bovine serum albumin-grown cells were deficient in lipid phosphorus. The three cultures did not show markedly different fatty acid compositions, but, in all cases, the cultures preferentially incorporated palmitic acid and discriminated against linoleic acid. Cultures grown for different times from logarithmic growth through a degenerative phase showed relatively constant ratios of cholesterol/protein and lipid phosphorus/protein. Fatty acid composition was also relatively constant at the different stages. Adenosine triphosphatase and p-nitrophenyl phosphatase were mainly associated with the membrane, whereas reduced nicotinamide adenine dinucleotide oxidase was either readily removed or not associated with the membrane. The reduced nicotinamide adenine dinucleotide oxidase was inactivated at temperatures above 35 degrees C.     

Action of mitomycin C on the variability of Actinomyces hygroscopicus in forming a proteolytic complex of hygrolytin enzymes and the antibiotic, hygromycin B]

The lethal and mutagenic effect of mitomycin C in doses of 10 and 15 micrograms/ml on the spores and 24-hour culture of Act. hygroscopicus, strain O878 producing hygrolytin, a proteolytic enzyme and hygromycin B, an antibiotic was studied. It was found that mitomycin C had a high lethal effect on the organism. The lethal effect of the antibiotic depended on the stage of the culture development, mitomycin C dose and exposure time. The 24-hour culture was most sensitive to the effect of mitomycin in a dose of 50 micrograms/ml. Exposure to mitomycin increased the actinomycete variation with respect to the colony morphology and induction of new morphological mutations. Exposure of strain O878 to mitomycin C significantly increased the culture variation with respect to the quantitative features of production of the hygrolytin proteolytic enzyme complex and hygromycin B. The character of the strain induced variation with respect to the features studied was different which indicated the absence of correlation between them. The use of mitomycin C proved to be promising in selection of Act. hygroscopicus with a purpose of increasing the culture proteolytic and antibiotic activity.     

Electron microscopic and biophysical studies of liposome membrane structures to characterize similar features of the membranes of Streptomyces hygroscopicus

To characterize the novel non-planar plasma membrane structure of bacteria (wafer structure), liposome membranes from the bacterial lipid mixture and individual lipid fractions were prepared and investigated by freeze-fracture electron microscopy, microcalorimetry and 31P-NMR spectroscopy. The phospholipid content of the membranes is essential for the formation of the non-planar membrane structure and there is no indication that the formation of the structure is connected with temperature-induced lipid phase transition processes. An exaggerated form of the wafer structure (raspberry structure) is also visible and additionally, in both cases, many small spherical vesicles are observed. We suggest that both membrane features of the liposomal and bacterial membranes are induced by these vesicles, forming a hexagonal or cubic organization of vesicles on the cytoplasmic surface of the biological membrane, and in between the multilamellae in the artificial membranes.     

Lymphocyte plasma membranes. III. Composition of lymphocyte plasma membranes from normal and immunized rats

Isolated plasma membranes of thymic and splenic lymphocytes from unimmunized and immunized rats of the inbred ACI and F344 strains were analyzed for chemical and enzymatic composition, for membrane protein patterns by polyacrylamide gel electrophoresis and for membrane-associated immunoglobulins. After immunization, the thymic and splenic lymphocyte membranes from F344 rat contained less carbohydrate and higher phospholipid contents than control animals. In both ACI and F344 inbred rat strains the membrane phospholipid to cholesterol weight ratio increased significantly after immunization. The electrophoretic patterns of solubilized membrane proteins and of iodinated external membrane proteins were similar in unimmunized and immunized animals.When thymic and splenic lymphocytes of normal or immunized animals were surface radioiodinated, solubilized in Triton X-100, NP-40 or 10 M urea in 1.5 M acetic acid and analyzed by immunoprecipitation, labeled IgM immunoglobulin was recovered from thymic lymphocytes but both labeled IgG and IgM were recovered from splenic lymphocytes. However, when unlabeled isolated plasma membranes were solubilized in 1% Triton X-100 and analyzed by immunodiffusion in agarose gels, both IgG and IgM were identified in thymic and splenic cells.     

Isolation of the membranes of Actinomyces sp. 26-115, a producer of actinomycin C]

A summation fraction of the membranes of Actinomyces sp. 26-115 was obtained as a result of lysis of its protoplasts in a hypotonic medium. The qualitative content of protein, lipids, phospholipids, nucleic acids, glucosamine and muramic acid was determined in the membranes at various stages of the organism development. Phosphatidylcholine is the main component of phospholipids in this organism. Intracellular actinomycin was found inside the protoplasts. Electrophoregrams of the microprotoplasts and membranes are presented. Actinomycin was also detected in the membranes. Still, it is not clear whether it is a component of the membrane or it is adsorbed on the membrane during the process of its isolation. The final conclusion on the relationship between the membrane and localization of actinomycin in the cell requires further investigation.     

Actinomyces thermovulgaris endospores

It has been established for the first time that autolysis observed when Actinomyces thermovulgaris T-54 is cultivated on liquid media of various composition is caused by the formation of submerged spores. These, in contrast to exospores of the majority of the actinomycetes, are endospores according to their structure and the following criteria: thermostability, the presence of dipicolinic acid, the structure of ultrathin cross-sections studied by electron microscopy, the resistance to novobiocin.     

Composition of the surface hydrocarbons from the vitelline membranes of dipteran embryos

Hydrocarbons were the major lipid class extracted by hexane from the vitelline membrane surface of dechorionated eggs of the house fly, Musca domestica, the New World screwworm, Cochliomyia hominivorax, the secondary screwworm, Cochliomyia macellaria, the green bottle fly, Phaenicia sericata, the sheep blow fly, Lucilia cuprina and the Mexican fruit fly, Anastrepha ludens. The length of time the embryos must be exposed to hexane with or without a small amount of alcohol in order to attain permeability was species-dependant. Long-chain n-alkanes comprised the major lipid class removed from vitelline membranes of all species except A. ludens where 2-methylalkanes were the major class. The range in size by the total number of carbon atoms in the hydrocarbons was: C23-C49 in C. hominivorax, C27-C33 in C. macellaria, C24-C35 in L. cuprina, C25-C36 in M. domestica, C25-C33 in P. sericata and C21-C51 in A. ludens. The major hydrocarbon component, expressed as percent of the total hydrocarbons, was n-nonacosane (C29) in C. hominivorax (40%), C. macellaria (43%), L. cuprina (38%), M. domestica (39%) and P. sericata (60%). However, in A. ludens, 2-methyloctacosane (32%) was the major hydrocarbon. Unsaturated hydrocarbons, monoenes (16%) and dienes (11%), were abundant only in A. ludens. Since prior studies indicated that the length of time the embryos must be exposed to hexane with or without a small amount of alcohol in order to attain permeability is species dependant, we suggest that the differences in hydrocarbon composition may contribute to this variation in lipid extractability.     

Composition of membranes and mycelia ofStreptomyces levoris at different stages of growth

The composition of cell membranes and mycelia ofStreptomyces levoris, producer of the polyene antibiotic levorin, was studied. The membrane protein/lipid ratio was shown to be constant during growth of the microorganism. The membrane protein was found to be heterogeneous and to have a low molecular weight. The lipid component of the membranes consisted mainly of polar lipids—phosphatidyl ethanolamine, diphosphatidyl glycerol, and phosphatidyl inositol mannoside being predominant. During growth, the phospholipid content of the polar lipid fraction decreased, apparently due to replacement of phospholipids by phosphorus-free analogs.