[Characteristics of [3H]cycloheximide distribution, protein and DNA biosynthesis in rat organs after sublethal blocking of translation]. / Osobennosti raspredeleniia [3H]tsiklogeksimida, biosintez belka i DNK v organakh krysy dosle subletal'nogo bloka transliatsii.

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. A positive correlation was observed between the decrease of CHI (or its metabolites) concentration and the beginning of protein and DNA syntheses in different organs. However, there was a reverse correlation between the high values of squares below the kinetic curves of CHI release from the liver, kidneys and adrenals and the intensive resumption of protein and DNA biosyntheses in these organs. It was thus assumed that in these particular organs CHI is subjected to intensive biotransformations. The contribution of the endocrine system to the induction of intensive compensatory protein and DNA syntheses in the liver were estimated from the viewpoint of the nature of reconstructive processes occurring in the appropriate organs.

[Metabolism of 18S-rRNA in rat liver cells in different functional states of the protein-synthesizing apparatus]. / Metabolizm 18S-rRNK v kletkakh pecheni krysy pri razlichnykh funktsional'nykh sostoianiiakh beloksinteziruiushchego apparata.

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]. / Degradatsiia 18S- i 28S-ribosomnykh RNK v tsitoplazme kletok pecheni krys pri podavlenii sinteza belkov.

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. The rapid decay of 18S rRNA is due to the degradation of this RNA in 40S ribosomal subunits. In contrast to 28S rRNA the specific radioactivity of 18S rRNA is increased by the 6th hour. Presumably the synthesis and processing of 18S rRNA impaired during the 1st hour are recovered partially or completely by this time. A molecular mechanism underlying 18S rRNA degradation in 40S ribosomal subunits is proposed.

[Biosynthesis of ribosomal RNA in rat liver cells after inhibition of protein synthesis]. / Biosintez ribosomnykh RNK v kletkakh pecheni krysy pri podavlenii sinteza belkov.

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]. / Aktivatsiia khromatina i proteoliza gistonov pri podavlenii sinteza belkov v kletkakh pecheni.

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 3.1.4.5) and in transformations of the DNA-histone interactions during the first 1-2 hours after inhibition of translation. This results in a temporary activation of chromatin which manifests itself in acceleration of RNA synthesis. Within 3 hours following the inhibition of translation the rate of proteolysis in the nucleus, the amount of acetylated forms of histone H3 and other acetylated proteins, the sensitivity of chromatin to DNAase I and the rate of RNA synthesis are decreased. It is assumed that at strong inhibition of protein synthesis one of the factors controlling chromatin activity is a specific proteolysis of modified histones.

[Allele specificity of genetic recombination in T4 phage using the indicator crossing study method]. / Issledovanie allel'-spetsifichnosti genticheskoi rekombinatsii u faga T4 metodom indikatornykh skreshchivanii.

The diagrams of relative correction ability of eighteen rII mutants of T4 phage were constructed on the basis of two-factor crosses, which were grouped into indicator series. In each series a pair of closely linked compared markers was crossed against indicator ones, the latter being distant enough so as to avoid simultaneous correction with the compared marker. The differences between the frequencies of wild type recombinants in crosses of two compared markers with indicator ones remained constant within the series and can be used as a measure of the differences between the compared markers in their correction ability. Mutants of base substitution type have small but statistically significant differences in correction ability. Simultaneous substitution of two bases in one codon yields a mutant which shows higher correction ability when compared to the mutant obtained as a result of substitution of only one base in the same codon. Frame shift mutants show much wider range of correctibility: some of them are corrected more rarely and others more frequently than base substitution mutants are.

[Contritution of correction to genetic recombination in T4 phage measured by the effect of map contraction]. / Vklad korrektsii v geneticheskuiu rekombinatsiiu u faga T4, izmeriaemyi po éffektu suzheniia karty.

Marker-dependence of the fine structure map contraction in T4 phage is studied in two-factor crosses between rIIB mutants separated by indicator distances. The genetic intervals, which were short as compared with mean length of the heteroduplex region in hybrid DNA molecules but which exceeded the length of the DNA strand involved in a single correction event, were selected as indicator ones. On the basis of a deviation of measured frequencies from additivity (map contraction) the marker-specific frequencies of wild type recombinants arising as a result of correction to the wild type (kappa (- leads to +)) were calculated. For the most of the marker studied both of the base substitution and frame shift type the frequencies kappa (- leads to +) have the values below 2.10(-4). In the case of three most highly corrected frame shift markers with kappa (- leads to +) being 14.10(-4)--17.10(-4), about ten percent of all mismatched regions are corrected to the wild type.

[Suppression of DNA-ligase deficiency and selective breeding of mutants and recombinants of T4 phage with phenotype rII]. / Supressiia nedostatochnosti po DNK-ligase i selektivnyi otbor mutantov i rekombinantov s fenotipom rII u faga T4

A number of methods which greatly simplify the introduction of frame shift mutations in the limited segment of the phage T4 rII genes were developed for studying genetical recombination between closely linked markers. These methods enable to construct multiple rII mutants with relatively small expenditure of labour. Suppression of gene 30 deficiency by rII mutations has been studied for a variety of conditions. The results obtained indicate that rIIB polypeptide is involved in two different activities: rIIB region which is dispensable for growth on lambda-lysogenic Escherichia coli strains behaves as indispensable in phenomenon of suppression of ligase deficiency.