[Peculiar features of forming radiation effects in inbred populations of Drosophila melanogaster differing in cytotype].

A comparative evaluation of the sensitivity of inbred wild-type flies differing in the cytotype to the action of low-intensity radiation of different duration was conducted taking into account the integral parameters of survival. The strong dependence of the frequency of radiation-induced DNA damage (in the neutralpH version) to the cells of individuals on the dose of low-intensity radiation and stages of spermatogenesis was established. The hyper-radiosensitivity was found in the individuals of Charolles (R-cytotype), Harwich (P-cytotype), and Oregon-R (H-cytotype) strains irradiated during the early stages of spermatogenesis (spermatogonia-spermatocytes) and containing in their genotype transposons Bari 1, P and hobo, respectively. While drosophila line Canton-S exhibited dysgenetic properties against the background of several cytotypes (E, I and M), the effect of hormesis was identified under the same experimental conditions. With the increase in the dose of low-intensity irradiation, the frequency of the DNA damage either increased (for Canton-S) or reduced (for Harwich and Charolles). At that, the profile of fertility and. survival of wild-type stocks studied was maintained at a significantly high level. The important role of the cytotype and mobile genetic elements responsible for its formation in the modification of the effects of low-intensity γ-radiation is shown.

[Induction of transpositions of hobo-elements in chronically irradiated cells of dysgenetic and non-dysgenetic individuals of Drosophila melanogaster].

This paper studies the effect of chronic γ-radiation of different intensities on the induction of hobo-elements in cells ofdysgenetic and non-dysgenetic drosophila species. The level of gonadal atrophy, DNA damage, and mutability of the mini-white locus is estimated. It is shown that the frequency of displacements of the hobo-elements increases with the increase in the chronic irradiation dose, where an essential role belongs to the maternal effect. The level of DNA damage in the cells of embryos and larvae varies and depends on the conditions of induction of hobo-transposons. Analysis of the PCR products showed that chronic irradiation in a certain range of accumulated doses is able to induce formation of new copies of the hobo-elements. At the same time, the structure of deleted hobo-sequences may vary in response to higher doses of irradiation.

[Estimation of the levels of radiation-induced P-element transposition in Drosophila melanogaster experimental populations and laboratory strains].

When experimental P + M populations were exposed to chronic gamma-irradiation (0.31 mGy/h), the highest instability level of the singed-weak (sn(w)) locus was observed in F3-F10 with a subsequent decrease and stabilization of the mutation rate. The sn(w) mutation rate was within the range of spontaneous variation in conditions of P-M hybrid dysgenesis and irradiation of males of the Harwich laboratory strain with active P elements at 1.61 mGy/h. The instability of the sn(w) locus was significantly higher at lower dose rates (0.23 and 0.31 mGy/h), suggesting a nonlinear dose-effect relationship.

[Evaluation of effects of gamma-irradiation at low doses on repair and meiotic recombination mutants of Drosophila melanogaster].

A comparative study of the effects of gene mutations mus209, mus309, mei-41 and rad54 of Drosophila melanogaster on the sensitivity to low-level exposure of different duration was carried out. Taken into account was the survival rate at different stages of ontogeny, female fecundity, the frequency of dominant lethal mutations (DLM) and the DNA damage. mei-41 and rad-54 mutants were most sensitive to the action of low dose radiation (80 mGy) in terms of survival and DLM. However, at the level of DNA damage, an increased radiosensitivity is observed only at larger doses of low intensity irradiation. Based on these observations, we can conclude about the importance of repair and its genes in the formation of the effect of low level doses of ionizing radiation in Drosophila.

[The radiationally induced change of level of double-stranded breaks DNA in neuroblasts of larvae and frequency of lethal mutations in sex cells of males Drosophila melanogaster].

The level of damage DNA in neyroblastes of larvae and frequency of recessive sex-linked lethal mutations of males from chronically irradiated populations Drosophila melanogaster, differing on mobile P-elements patterns, was estimated. Received results testify, that exposition in conditions a chronic gamma-radiation (absorbed radiation dose at one generation is compounds 10 mGy) result to increase of significance of parameters and change of sensitivity of cells to following of an acute irradiation in a dose of 3 Gy.

[The dynamics of variability of the genotype of experimental populations of Drosophila melanogaster by chronic radiation exposure].

The reaction on the irradiation in a dose 3 Gy of experimental populations of Drosophila melanogaster, differing on mobile genetic element patterns, chronically irradiated in low doses ionising radiation was investigated. Received results testify that the effect of radioadaptation is found out only in populations with an initial genotype and is not revealed at populations containing P-mobile elements. It is shown, that in chronically irradiated populations D. melanogaster with an initial genotype, decrease in frequency recessive lethal mutations after a sharp irradiation in a dose 3 Gy is observed. The analysis of frequency of dominant lethal mutations and gonads atrophy such tendency has not revealed. It is supposed, that the mechanisms participating in formation of the adaptive answer, induced with an irradiation and transpositions activity of mobile elements differ.

[The dynamics of survival rate of experimental polulations of Drosophila melanogaster undergone to a chronic irradiation].

In genetically non-uniform populations Drosophila melanogaster in conditions of a chronic irradiation in a doze 10-11 sGy/generation dynamics parameters of populations was investigated. It is established, that number of individuals in irradiated populations is lower, than in control. It is revealed, that viability of populations undergone to a chronic irradiation depends on their genotype. The gradual increase in fruitfulness, viability of individuals and the decrease in a level of lethal mutations in a number of generations after an irradiation in small dozes is caused by adaptable opportunities of the populations.

[Genetic aspects of the irradiation in small doses of laboratory lines and experimental populations Drosophila melanogaster].

One of explanations of revealed effects of small doses of an irradiation is induced genetic instability on which background there is a realization of the various radiobiological reactions resulting as to stimulation, and significant oppression of the vital functions of a cell or an organism. In work the given estimations of consequences of an irradiation in small doses of mutant lines of the drosophila are submitted. Paramount value in definition of their size and an orientation of reaction of a genotype is supposed, that, have processes leaders to change of activity of mobile genetic elements and programmed destruction of a cell.