Virus-like particles in Cephalosporium acremonium. (73/206)

Cephalosporium acremonium cultures were studied for the presence of virus-like particles. Relatively few particles were found in the preparations, indicating that the number of particles present in these cells may be much lower than in Penicillium species.  (+info)

Proteins of a polyhedral cytoplasmic deoxyvirus. 3. Structure of frog virus 3 and location ov virus-associated adenosine triphosphate phosphohydrolase. (74/206)

The adenosine triphosphatase associated with frog virus 3 shows high specificity for ATP or deoxyadenosine triphosphate and appears to be distinct from the corresponding activity in host cells, poxvirus, or reovirus. The enzyme activity is probably integrated into virus particles since it is firmly associated with subviral particles produced when approximately 50 to 60% of the outer viral protein is removed by detergent treatment. The occurrence of adenosine triphosphatase activity within three unrelated viruses suggests that adenosine tryphosphatase might be a necessary function for most viruses that replicate in the cell cytoplasm.  (+info)

Proteins of vesicular stomatitis virus and of phenotypically mixed vesicular stomatitis virus-simian virus 5 virions. (75/206)

The identity of the glycoprotein of vesicular stomatitis virus (VSV) as the spike protein has been confirmed by the removal of the spikes with a protease from Streptomyces griseus, leaving bullet-shaped particles bounded by a smooth membrane. This treatment removes the glycoprotein but does not affect the other virion proteins, apparently because they are protected from the enzyme by the lipids in the viral membrane. The proteins of phenotypically mixed, bullet-shaped virions produced by cells mixedly infected with VSV and the parainfluenza virus simian virus 5 (SV5) have been analyzed by polyacrylamide gel electrophoresis. These virions contain all the VSV proteins plus the two SV5 spike proteins, both of which are glycoproteins. The finding of the SV5 spike glycoproteins on virions with the typical morphology of VSV indicates that there is not a stringent requirement that only the VSV glycoprotein can be used to form the bullet-shaped virion. On the other hand, the SV5 nucleocapsid protein and the major non-spike protein of the SV5 envelope were not detected in the phenotypically mixed virions, and this suggests that a specific interaction between the VSV nucleocapsid and regions of the cell membrane which contain the nonglycosylated VSV envelope protein is necessary for assembly of the bullet-shaped virion.  (+info)

Inactivation of polykaryocytogenic and hemolytic activities of Sendai virus by phospholipase B (lysolecithinase). (76/206)

Evidence is presented that lysolecithin is involved in the fusing and hemolytic activities of Sendai virus. Treatment of the virus with phospholipase B (lysolecithinase) specifically inactivates the hemolytic and fusing abilities, without affecting the infectivity and the capability of the virus to hemagglutinate and adsorb to cells. The possible identity of lysolecithin with the "cell fusion factor" of paramyxoviruses and the mechanism of cell fusion are discussed.  (+info)

Spontaneous degradation of reovirus capsid into subunits. (77/206)

When a plaque-purified strain of reovirus type 3 (Dearing strain) degraded during storage, electron micrographs of the degraded virion were made which clearly demonstrated the substructural components of the outer capsid.  (+info)

Effect of polymyxin on the bacteriophage receptors of the cell walls of gram-negative bacteria. (78/206)

Treatment of gram-negative bacteria with lethal doses of polymyxin B and colistin resulted in the formation of projections of the outer layer of the cell wall. Phages T3, T4, and T7, which use wall lipopolysaccharide as receptors, were specifically prevented from adsorbing to Escherichia coli B cells treated with polymyxin, whereas phages T1, T2, T5, and T6 were not. In the systems of phage P22C-Salmonella typhimurium LT2 and phage C21-S. typhimurium variant SL1069, the phage were prevented from adsorbing to the host cell treated with the antibiotics. Electron microscopic observations show that phage T2 adsorbed irreversibly to the normal smooth surface between the projections on the outer layer caused by the drug treatment. These results indicate that lipopolysaccharide is affected by polymyxin functionally and morphologically, but lipoprotein is not. The purified lipopolysaccharide showed a ribbon-like structure when viewed face on and showed trilamellar structure when viewed edge on. The lipopolysaccharide from E. coli B was irreversibly adsorbed by phages T3, T4, and T7, but not phage T2. Often, phage T4 adsorbed to both sides of the lipopolysaccharide strand at comparable distances. Phage P22C adsorbed through the spikes of the tail-plates to the lipopolysaccharide from S. typhimurium LT2. Lipopolysaccharide which was treated with low doses of the drug (2.5 to 6.25 mug of polymyxin B per ml to 100 mug of lipopolysaccharide per ml) turned into the coiled form and was partially broken down into short segments with coiled form. The loosely coiled lipopolysaccharide retains both its function as the receptor and its trilamellar structure. Treatment with high doses of the drug (12.5 to 25 mug of polymyxin B per ml to 100 mug of lipopolysaccharide per ml) caused the collapse of the trilamellar structure of the strand. These collapsed lipopolysaccharides became flat and fused with each other, making an amorphous mass, and finally they were broken into small collapsed fragments.  (+info)

Lack of distinction between Nitrobacter agilis and Nitrobacter winografskyi. (79/206)

No adequate criteria were established to distinguish between Nitrobacter agilis and N. winogradskyi. However, very gentle preparative techniques permitted demonstration of flagella in N. agilis.  (+info)

Restoration of deoxycholate-disrupted membrane oxidases of Micrococcus lysodeikticus. (80/206)

Membrane-associated l-malate and reduced nicotinamide adenine dinucleotide (NADH) oxidase complexes of Micrococcus lysodeikticus were inactivated with deoxycholate. Reactivation of NADH oxidase by addition of Mg(2+) occurred in these detergent-membrane mixtures, but reactivation of l-malate oxidase did not occur in the presence of deoxycholate. Removal of detergent by gel filtration allowed Mg(2+)-dependent restoration of both l-malate and NADH oxidases. Maximal NADH and l-malate oxidase restoration required 10 min and 40 min, respectively, at 30 mm MgSO(4). Maximal restoration of both oxidases required at least 12 mm MgSO(4) in an incubation period of 1 hr. Reduced-minus-oxidized difference spectra of Mg(2+)-restored membrane oxidases showed participation of cytochromes b, c, and a when either l-malate or NADH served as reductant; addition of dithionite did not increase the alpha- and beta-region absorbancy maxima of these hemoproteins when restored membranes were first reduced with the physiological substrates l-malate or NADH. Not all divalent cations tested were equally effective for reactivation of both oxidases. l-Malate oxidase was restored by both Mn(2+) and Ca(2+). NADH oxidase was not activated by Mn(2+) and only slightly stimulated by Ca(2+). Separation of deoxycholate-disrupted membranes (detergent removed) into soluble and particulate fractions showed that both fractions were required for Mg(2+)-dependent oxidase activities. Electron micrographs indicated conditions of detergent treatment did not destroy the vesicular nature of protoplast ghost membranes.  (+info)