[Genoprotective effect of drugs based on ecdysteroids in poisoning of rats with tetrachloromethane and chlorophos].

Molecular mechanisms of chromatin damage have been investigated during tetrachloromethane and chlorophos intoxication of experimental animals. Introduction of tetrachloromethane to experimental animals induced chromatin degradation causing a partial loss of histone H1-DNA fragmentation and formation of intermolecular bonds: DNA-protein. Intoxication with chlorophos results in repression of a part of genes due to augmented chromatin compactness.

[Biochemical characterization of fractionated rat liver chromatin in experimental D-hypovitaminosis and after administration of steroidal drugs].

Marked changes in the structural and functional characteristics of liver nuclear chromatin fractions are observed under experimental D-hypovitaminosis, which differ in the degree of transcriptional activity. DNA-polymerase activity and activity of the fraction, enriched with RNA-polymerase I, increases in the active fraction. Free radical LPO reactions are modified in the chromatin fraction with low activity and to the less degree in the active one.

[Changes in protein, lipid composition, DNA- and RNA- polymerase activity of the chromatin fraction and the nuclear matrix of the rat liver in hypovitaminosis E].

E-hypovitaminosis-induced antioxidant deficiency in rats causes changes in some properties of nuclear structures of the liver cells, i.e. fractions of transcriptionally active and repressed chromatin and nuclear matrix.

[Lipid peroxidation and parameters of thermodenaturation of chromatin fractions in the rat liver].

The fractions of transcriptionally active and repressed chromatin of the rat liver include lipids, whose fatty acid residues are the substrates of lipid peroxidation (LP) processes. In vitro incubation in NADPH- and ascorbate-dependent LP systems resulted in the activation of peroxidation in the liver chromatin of intact animals, estimated from malonic dialdehyde (MDA) accumulation, the LP processes proceeding more intensely in the fractions of transcriptionally active vs. repressed chromatin.

[Structural-functional characteristics of chromatin fractions in the regenerating liver of adult and old rats].

The transcriptional activity, nucleosomal patterns, and thermodenaturation parameters of low-active and active fractions of liver chromatin were studied in adult (6-8 mo) and old (26-28 mo) rats at 2, 4, and 6 weeks after partial hepatectomy. At 2 weeks postoperatively, there was a decrease in relative specific radioactivity (RSR) of the active chromatin fraction in adult rats, which returned to normal by the 4th week, while in the low-active fraction it was decreased throughout all the studied regeneration periods. The decrease of the low-active fraction RSR was attended with changes in the nucleosomal organization and DNA-protein interactions revealed by electrophoresis and thermodenaturation.