[Structural changes of chromatin during proto-oncogene activation by cycloheximide: dose-effect].

The level of expression of cellular proto-oncogens c-myc and c-fos in rat liver has been studied as a function of protein synthesis rate (cycloheximide dose). Activation of proto-oncogens has been established to be initiated by 50% inhibition of nuclear protein synthesis. This promotes a certain level in chromatin structural rearrangements which is manifested, in particular, in decreasing activity of chromatin cleavage by Ca2+, Mg(2+)-DNAase and increasing degree of chromatin condensation.

[Effects of D-penicillamine on the ultrastructure of hepatocytes and state of the base substance in the liver of rats with experimental cirrhosis].

The authors examined the action of D-penicillamine on the ultrastructure of hepatocytes and the condition of the base substance in the rat's liver, with experimental CCl4-cirrhosis. (D-penicillamine was given to these rats during 4 and 6 months). It was discovered that the using of D-penicillamine on the early stages of experiment (until 4 months) reduced the process of the development of the liver cirrhosis.

[Effect of cycloheximide on lipid metabolism in cells, nuclei and subcellular fractions in the rat liver].

Well coordinated stages of inhibition, restoration and stimulation of protein, DNA and RNA synthesis were observed after administration of cycloheximide (3 mg/kg). The changes in lipid synthesis and composition in the nuclei and intranuclear structures were studied at different stages of cycloheximide action. The accumulation and stimulation of lipid synthesis in the nuclei during the inhibition and restoration of protein and DNA syntheses were followed by electron microscopy and labeled precursors methods.

[Perfusion method of fixing and incubating alkaline phosphatase in the rat liver for cytochemical study].

A perfusion method is described for the ultrastructural demonstration of alkaline phosphatase. The present approach is based on a short vascular perfusion of the rat liver with glutaraldehyde through the portal vein or the aorta, followed by a vascular perfusion incubation with a medium containing the enzyme substrates. From the vessels a good penetration of the medium into all tissues is achieved.

[Electron microscopic study of Bacillus subtilis mutants differing in the serine proteinase activity and spectrum].

Vegetative cells and spores of the colonial morphological mutants of Bacillus subtilis A-50 were studied by electron microscopy. The ultrastructure of vegetative cells from both asporogenic colonial-morphological mutants and those which were capable of forming spores in the presence of high concentrations of nitrogen and carbon sources with a decreased activity and a modified spectrum of serine proteases differed from the parent strain by the presence of a microcapsule, the uneven thickness of a cell wall, and the absence of a distinct periplasmic space. Crystalline inclusions of a regular shape were detected in the sporeforming mutant in those cells which were devoid of spores.

[Morphogenesis and function of gas caps on spores of anaerobic bacteria of the genus Clostridium].

Contrary to other bacteria, those belonging to the genus Clostridium have their formation of vacuoles being strictly confined to the stage of spore production. In Clostridium, gas vacuoles are formed in the intraexosporial space, i. e.

[Ultrastructural organization of trichomes of a new group of multicellular gram-negative bacteria].

Peculiar trichome multicellular gram-negative bacteria were found in several types of soil, and were isolated as pure cultures. The bacteria are characterized by the following properties: (a) the presence of large regions of the periplasm, 200-300 nm thick, in the cells, the volume of the periplasm being greater than that of the cytoplasm; (b) a peculiar structure of multicellular trichomes in which the cells are surrounded by a common cell wall and a common periplasmic space; (c) a specific structure of trichome septa formed by membrane leaves and including no material of the cell wall; (d) the ability of protoplasts to divide within the trichome cell wall; (e) the ability to grow under anaerobic conditions. Therefore, these organisms belong to a new group of trichome multicellular bacteria.