[Mathematical analysis of genetic effects of low doses of ionizing radiation]. / Matematicheskii analiz geneticheskikh éffektov malykh doz ioniziruiushchikh izluchenii.

The comparative study of effects of low doses of radiation on peripheral blood lymphocytes of persons occupationally exposed to radiation and non-exposed ones was carried out. The main attention was paid to radio-adaptive response forming under consistent exposure to low (0.05 Gy) and damaging (2 Gy) doses of gamma-irradiation. Noticeable heterogeneity in capacity for adaptive response forming in occupational group was revealed. The mathematical model adequate to experimental material was constructed using Kohonen neuronets.

[Genetic analysis of recessive lethal mutations induced by the influenza virus in the X chromosome of Drosophila melanogaster]. / Geneticheskii analiz retsessivnykh letal'nykh mutatsii, indutsirovannykh virusom grippa v X-khromosome Drosophila melanogaster.

Mutagenic potential of the influenza virus was evaluated. Based on its capacity of inducing recessive lethal mutations in the X chromosome of Drosophila melanogaster, the influenza virus can be classified as a moderate-activity mutagen. Its mutagenicity does not depend on ability to reproduce in the cell system. This virus was shown to disrupt formation of the wing, particularly wing vein M1 + 2. Cytogenetic examination of polytene X chromosomes bearing recessive lethal mutations in Drosophila salivary glands did not reveal chromosome rearrangements. These lethals are assumed to be small deletions or point mutations. The determination of the lethal activity stage of these mutations showed that they disrupt the expression of genes functioning at various developmental stage of Drosophila. Two of them were conditionally lethal (temperature-sensitive). Two of 15 mutations analyzed were mapped to region 2B9-10-3C10-11.

[Frequency of chromosome aberrations in residents of the Semipalatinsk Oblast]. / Chastota aberratsii khromosom u zhitelei Semipalatinskoi oblasti.

Cytogenetic analysis of the population of the Beskaragai district of the Semipalatinsk oblast adjacent to the territory of the nuclear test site was conducted by means of an ecological genetic questionnaire and cytogenetic examination of metaphase chromosomes. An increase in the total mutation level in the region was observed. The frequency of chromosome aberrations among the population of the Beskaragai district (3.2%) was statistically significantly (about 1.5 times) higher than the background levels in the clear regions (from 1 to 2%). Furthermore, the frequency of aberrations in adolescents was comparable with that in the adults. The spectrum of chromosome aberrations pointed to a significant contribution of radiation component to the mutagenesis.

No evidence for radiation-induced clastogenic factors after in vitro or in vivo exposure of human blood.

Experiments were performed with human plasma irradiated in vitro or in vivo in order to evaluate the extent to which clastogenic factors might disturb the adaptive response to DNA-damaging factors currently studied in our laboratory. The studies were carried out with plasma isolated from whole blood given 4 Gy of X-rays in vitro and with plasma from people receiving local radiotherapy at a total dose of about 60 Gy gamma rays. Addition of irradiated plasma to culture medium did not result in a statistically significant increase in structural aberrations in chromosomes of non-irradiated normal blood.

[Interferon activates DNA repair genes in UV-irradiated human cells]. / Interferon aktiviruet geny reparatsii DNK v UF-obluchennykh kletkakh cheloveka.

Unscheduled DNA synthesis in human fibroblasts pretreated with natural and recombinant interferons was studied by scintillated radiometry. UDS was increased in fibroblasts pretreated 7 days before UV-irradiation. Newly synthesized proteins induced in cells after interferon treatment were compared with heat shock proteins.

[Mechanism of the antimutagenic effect of interferon in human fibroblasts based on induced protein analysis]. / K mekhanizmu antimutagennogo deistviia interferona v fibroblastakh cheloveka na osnove analiza indutsirovannykh belkov.

Proteins induced in human fibroblasts after treatment of some antimutagens (interferon, p-aminobenzoic acid, heating and vaccinia virus infection) were identified by means of polyacrylamide gel electrophoresis (10-15%) followed by fluorography of the gel. Influenza virus proteins (A/WSN/33) were used as markers to determine the molecular weights of the new proteins. The results obtained suggest that interferon, p-aminobenzoic acid, heating and vaccinia virus infection induced proteins with mol. weights of 24 and 18 kD except the protein with 76 kD observed only after heating insult.

[Infection of repair-deficient human cells by the vaccinia virus decreases the formation of gamma-induced DNA breaks]. / Infitsirovanie reparativno-defektnykh kletok cheloveka virusom ospovaktsiny snizhaet formirovanie gamma-indutsirovannykh razryvov DNK.

The alkaline elution method was used to study DNA breaks induced by the different mutagens in human cells. Normal fibroblasts and fibroblasts from patients with homocystinuria, deficient in gamma-type repair were shown to be resistant to gamma-radiation after the vaccinia virus infection. In both cell lines there was a decrease in the number of the mutagen-induced DNA breaks.

[Optimization of protective properties of interferons in human cells exposed to mutagens estimated by the DNA repair activity]. / Optimizatsiia zashchitnykh svoistv interferonov v kletkakh cheloveka pri vozdeistvii mutagenami po kriteriiam otsenki reparativnoi aktivnosti DNK.

Protective properties of human interferons against physical and chemical mutagens have been described earlier. This work was aimed at detecting an optimum of protective action of interferons in human fibroblasts using two criteria: the number of single-strand DNA breaks formed and the index of DNA repair synthesis. The protective ability of interferon was shown to be expressed starting after 4 h of cells' pretreatment and proceeding through 40 h in experiments with N-methyl-N-nitro-N-nitrosoquanidin. The phenomenon of stimulation of DNA repair synthesis in human cells pretreated with interferon proceeded even after replating cells during 8 h in the experiments with UV irradiation.

[Effect of nitrosourea in small doses on the frequency of mutation in Salmonella typhimurium]. / Vliianie nitrozomocheviny v malykh dozakh na chastotu mutatsii u Salmonella typhimurium.

The effect of N-nitroso-N-methylurea (NMU), N-nitroso-N,N'-dimethylurea (NDMU) and N-nitroso-N-ethylurea (NEU) at doses less than 100 mkg/ml on mutability of Salmonella typhimurium strains of Ames' system (G-46, TA-1950, TA-1535, TA-100, TA-1538) has been studied. NMU and NEU at doses of 5-10 mkg/ml have been found to increase the survival and decrease the number of reversions from auxotrophity in histidine to prototrophity. The effect of given doses of NMU and NEU on bacteria repair activity has been shown. The role of pk M101 plasmide in this process is being discussed. NDMU in contrast to NMU and NEU induces read frome shift mutations and exhibits high mutagenous activity at all doses examined.

[Effect of nonmutagenic doses of 1,4-bis-diazoacetylbutane on Streptomyces griseus]. / Vliianie na Streptomyces griseus nemutagennykh doz 1,4-bis-diazoatsetilbutana.

Streptomyces griseus 15 was subjected to the action of 1,4-bis-diazoacetyl butane (DAB) taken at concentrations of 10 to 50,000 micrograms/ml. Small doses (10-100 micrograms/ml) of DAB had no mutagenic action and activated the cultural growth (the viability and the survival rate of spores increased on solid media, while the biomass yield rised in liquid media). Experiments were conducted using the method of orthogonal planning of a bifactorial experiment, and the role of the exposure time rised with a decrease in the mutagen concentration.

[Biologically active ribonucleoproteins of cells infected with fowl plague virus]. / Biologicheski aktivnye ribonukleoproteidy kletok, zarazhennykh virusom chumy ptits.

The results of studies of physico-chemical and biological properties of virus-specific ribonucleoproteins (RNP) in influenza infection are presented. Particular attention is given to the infectious properties of RNP. The earliest infectivity was found to be associated with RNP structures sedimenting from nuclear extract in a zone of 30-40S.