PubMed Health⌕ Search

Biomedical subjects

V G Bezlepkin

Publications and source records attributed to V G Bezlepkin.

28 records · Page 2Linked to original sources

[Genome instability in the F1-progeny of mice irradiated by ionizing radiation as determined by micronucleus assay].

The F1-progeny of BALB/c male mice chronically exposed to low-dose gamma-radiation (0.1; 0.25 and 0.5 Gy; dose rate 0.01 Gy/day) as well as the F1-progeny of females exposed to acute X-radiation (0.5; 1.0 and 2.0 Gy; dose rate 0.1 Gy/min) shown the significant elevated micronuclei frequencies in bone marrow erythrocytes, as compared to the F1-progeny of unirradiated males and females. The increase in the micronuclei frequency in the F1-progeny was determined by the dose of irradiation of parents. The values of elevated micronuclei frequency in the F1-progeny of chronically irradiated males and acutely irradiated females for a dose of 0.5 Gy were comparable. The micronuclei frequencies in the F1-progeny of irradiated females and males for this dose were in 1.5 and in 1.6 times higher than ones in the F1-progeny of unirradiated mice correspondingly. The results suggest the possibility of transfer of genome instability from irradiated parents to the somatic cells of the F1-progeny via non-lethally damaged germ cells of parents.

Animals↗

[The DNA-mediated transformation of mouse fibroblasts after radiation damage to the cellular chromatin].

In experiments with NIH3T3 mouse fibroblast the authors showed a dose-dependent (gamma- or UV-radiation) increase in the immortalized fibroblast transformation by purified DNA preparations from Ehrlich ascites tumour cells. The transformant yield was the highest when the transfection started within the first few minutes after irradiation, when radiation lesions occurred in the genome and the system of enzymic DNA repair was activated. The proteolytic activity inhibition by treating the exposed cells with phenylmethanesultonyl fluorine reduced the radiation-induced transformation.

Animals↗

[Possibility of the existence of a pre-incision stage of DNA repair].

A study was made of the influence of protease activity inhibition by phenylmethylsulfonyl fluoride and modification of the chromatin structure by polyamines on the rate of formation and repair of DNA single-strand breaks in 3T3 cells affected by UV- or gamma-radiation. The results obtained suggest that a change in the chromatin structure, with the participation of the proteolytic activity, may be a stage preceding endonuclease incision in the process of excision DNA repair.

Animals↗

[Synthesis of DNA in dividing and quiescent cells following gamma-irradiation].

Changes in clonogenic capacity of gamma-irradiated minimally transformed 3T3 cells (Do = 1.3 Gy, D37 = 5 Gy, and Dq = 5.3 Gy) were determined and conditions for obtaining dormant population of these cells were chosen to be adequate for registering the radiation-induced unscheduled DNA synthesis. The comparison between the postirradiation changes in DNA synthesis in dividing and resting 3T3 cells suggests the participation of DNA-polymerase alpha in providing the unscheduled DNA synthesis in resting cells after gamma-irradiation with doses of 5 to 50 Gy.

Animals↗

[Induction of unscheduled DNA synthesis in the nuclear matrix of rat hepatocytes after whole-body gamma irradiation of the animals].

DNA synthesis in hepatocytes was studied by incorporation of [3H]thymidine administered to portal vein of gamma-irradiated (80 Gy) rats. It was shown that the rate of replicative DNA synthesis decreased in hepatocytes of the regenerating liver and unscheduled DNA synthesis was induced at the nuclear matrix of resting cells of the intact liver. In addition to repair synthesis, DNA synthesis resembling replicative one ("aberrant" DNA synthesis) accounts for a considerable fraction of gamma-radiation-induced synthesis of DNA at the nuclear matrix.

Animals↗

[Relation of the poly(ADP-ribosylation) of proteins to the formation and repair of DNA single-strand breaks in gamma-irradiated permeable Zajdela hepatoma cells].

A study was made of the effect of poly(ADP-ribosylation) of proteins on the formation and repair of single-strand DNA breaks in gamma-irradiated (50 Gy) permeable Zajdela ascites hepatoma cells permeabilized by the treatment with 0.05% triton X-100. Incubation of gamma-irradiated permeable cells in conditions promoting DNA synthesis and providing ADP-ribosylation (in the presence of 1 mM NAD) did not cause any substantial changes in the formation of single-strand DNA breaks and did not influence their repair.

Animals↗

[Initiation of unscheduled synthesis on DNA sites associated with a nuclear matrix of irradiated hepatoma cells].

A study was made of the distribution of unscheduled DNA synthesis (induced by UV- or gamma-radiation and resistant to hydroxyurea) between the DNA sites in the nuclear matrix and total nuclear DNA of Zajdela ascites hepatoma cells. It was shown that during the first 1.5 to 5 min of the postirradiation incubation the rate of the unscheduled synthesis of DNA was considerably higher in the DNA fraction, firmly associated with the nuclear matrix proteins, than in the total nuclear DNA.

Animals↗

[DNA-polymerase activity and DNA synthesis in the hepatocyte nuclear matrix].

The comparative analysis of DNA-synthetase activity of hepatocytes, isolated nuclei and nuclear matrix from normal and regenerating rat liver was performed. The highest enrichment with newly-synthesized DNA was registered in the DNA fraction associated with the nuclear matrix both in vivo and in vitro. The functioning of DNA polymerases alpha and beta in the matrix was shown. Our results indicate that DNA polymerase beta is more firmly bound with the nuclear matrix in the cells of normal liver but this enzyme is eluted almost completely from the nuclei of regenerating liver cells. At the first moment after gamma-irradiation of rats the preferential initiation of unscheduled DNA synthesis in vivo has been observed on the nuclear skeletal structures. This may serve as an indication on the possibility that DNA repair process occurs on the nuclear matrix.

Animals↗