[Characteristics of [3H]cycloheximide distribution, protein and DNA biosynthesis in rat organs after sublethal blocking of translation].

The kinetics of accumulation and release of [3H]cycloheximide (CHI) as well as protein and DNA biosyntheses in some organs of the rats injected with sublethal doses of CHI were studied. It was shown that in the majority of organs under study (especially in the liver, kidneys and adrenals) the inhibition is completed within 12 hours after CHI injection followed by the resumption of protein and DNA syntheses. In the thymus and pancreas the levels of these biosyntheses remain below control values up to the 72nd hour.

[Metabolism of 18S-rRNA in rat liver cells in different functional states of the protein-synthesizing apparatus].

The ratio of absolute radioactivities of 28S and 18S ribosomal RNA in membrane-bound and free polysomes and in free ribosomes of rat liver were studied under conditions of translation inhibition by cycloheximide, insulin and cAMP. Insulin and cAMP, in contrast with cycloheximide, did not induce selective degradation of 18S-rRNA. The data obtained are discussed in terms of the feasible role of S6 protein phosphorylation in degradation of the 40S ribosomal subunit.

[Degradation of 18S and 28S ribosomal RNA in the cytoplasm of rat liver cells after inhibition of protein synthesis].

Inhibition of protein synthesis (up to 95%) in starved rat liver cells after a single injection of a sublethal dose of cycloheximide (0.3 mg per 100 g of body weight) results in degradation of 18S rRNA during the first 3 hours, whereas the 28S rRNA remains unaffected. However, the increase of 28S rRNA degradation products was observed by the 6th and 12th hours.

[Biosynthesis of ribosomal RNA in rat liver cells after inhibition of protein synthesis].

Ribosomal RNA synthesis in starved rat liver cells after a single injection of sublethal dose of cycloheximide (3 mg per kg of body weight) was studied. An increase in the rate of nuclear ribosomal RNA synthesis was observed during the first 2 hours after cycloheximide injection followed by a noticeable decrease of synthesis by the 3rd hour. It was assumed that the stimulation of ribosomal RNA synthesis is correlated with the increase in the rate of transport from the cytoplasm to the nuclei of RNP proteins and of proteins involved in regulation of genome transcription.

[Activation of chromatin and histone proteolysis during protein synthesis inhibition in liver cells].

The initial response of rat liver chromatin to strong (up to 95%) inhibition of protein synthesis by cycloheximide consist in activation (2-3-fold) of proteolysis of weakly bound nuclear histones, especially of the acetylated histone H3, in a decrease (7-8-fold) of the rate of histone acetylation, in an increased sensitivity of chromatin to DNAase I (EC 3.1.4.