[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.

[Ecological and genetic monitoring of muridae from populations undergone to the chronic irradiation].

In work the data of long-term researches of consequences of chronic irradiation and radioactive pollution on a population of muridaea living in a zone of failure on the Chernobyl atomic power station and in territory of Northern radioecological station are resulted. It is shown, that chronic influence by investigated factors leads to authentically significant change of size of the genetic load determined on a level cytogenetic damages, intensity of reproduction, fertility.

[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.

[The influence of low doze gamma-irradiation on life span of Drosophila mutants with defects of DNA damage sensation and repair].

It was shown that life span of wild type strain Canton-S increased after low doze gamma-irradiation. It was revealed the decrease of life span after irradiation in Drosophila mutants with defects of DNA damage sensation and repair genes mei-9 and mei-41, both in homozygous and heterozygous lines. In mei-41 line males' lives longer than females in contrast to other lines.

[The hormonal and genetic effects induced by an irradiation in small dozes at Tradescantia (a clone 02)].

The purpose of the present work was studying the possible interrelation of the hormonal status of plants and size of the genetic effects induced by an irradiation in small dozes. The frequency of somatic mutations in strings Tradescantia (a clone 02) at an irradiation in dozes up to 28 cGy was estimated. Influence radiations in a range from background up to 28 cGy on the maintenance in inflorescences Tradescantia (a clone 02) the basic groups of plant hormones is investigated: abscisic acid, cytokinin, auxin and gibberellin A3. It is shown, that small dozes of an irradiation cause extremely radical changes of hormonal balance in fabrics of inflorescences Tradescantia. Received results are discussed with attraction of the data on influence phytohormones on kinetics a cellular cycle.

[Genetics aspects of different light regime influence on drosophila life span].

It was analyzed the difference of Drosophila life span in strains with low activity of Sod or excision repair enzyme Mus210 (homolog of yeast RAD4 and mammal XPC) in comparison with wild type strain Canton-S in conditions of 24 h and 0 h light. Mutants having low capacity to detoxify free radicals and repair DNA are characterized by stronger difference between life span at 24 h and 0 h light in comparison with wild type strain. Thus the life span increasing in the dark is due to decline of free radical and DNA lesions production. In wild type strain the effect of 12 h dusky light had not more effect on life span than intensive 24 h light. In most cases the difference between life span at 0 h and 24 h light was too much in males than in females, especially in Sod strain.

[The influence of ecdysone-containing phytopreparations on life span of Drosophila melanogaster strains depending on the genotype].

The longevity of Drosophila strains has been investigated after treatment by a hormone 20-hydroxyecdysone (80% solution) and a phytoecdysteroid-containing metaverone preparation (contains 5-7% of 20-hydroxyecdysone) in preimaginal stages of development. It is shown, that life expectancy of ecdysone-deficient woc strain exceeds life expectancy of wild type Canton-S strain by 46%, whereas ecdysone or metaverone treatment removes these distinctions. At the same time, treatment by ecdysteroid-containing preparations of Canton-S has not induced any essential alteration of life span. Thus, the new ageing gene woc has been discovered, the woc mutation essentially increases the life span of Drosophila, and its effect is mediated by a hormone 20-hydroxyecdysone and has the threshold corresponding natural physiological concentration of this hormone in an insect organism. The data have confirmed the conception of "antagonistic pleiotropy" according to which only mutations having advantages during the prereproductive and reproductive period are fixed in evolution, and their negative effect is delayed up to a postreproductive stage of life cycle. As a result we can see accumulation with age of structural and functional damages which increase probability of death. Indeed, genes of ecdysone synthesis play fundamentally important role in early development and sexual reproduction of insects, however essentially reduce their life span.

[The influence of gamma-irradiation in low doses on the rate of dominant lethal mutations in drosophila melanogaster].

The dose-rate effect of acute and chronic irradiation in the dose of 0.2 Gy in Drosophila melanogaster repair (mei-41, mus209 [Russian character: see text] mus309) and free radicals detoxication (sod) mutant strains was investigated. Was shown the lack of dose rate effect on the rate of dominant lethal mutations in mei-41, mus209 and sod. However in mus309, that has defect in the main Drosophila pathway of the DNA double strand breack repair, the increase of the mutation rate after chronic irradiation was observed (inverse dose-rate effect). The obtained results suggest the main role of DNA double strand breack repair in dose-rate effect formation in Drosophila.

[Life-span in generations of chronic irradiated Drosophila wild type isogenic and geterogenic strains].

With the goal to study radioadaptation on life-span and observe the role in this phenomenon of genotype, we investigated the dynamics of life-span in 14 consistent generations after chronic gamma-irradiation in heterogenic (Canton-S) and isogenic (Oregon-R spa) Drosophila wild type strains. The gamma-source was 226Ra in dose 60 cGy per generation. The animals kept in standard conditions (25 degrees C and 12 h lighting). Was shown, that the dynamics of median life-span in wild type strains Canton-S and Oregon-R spa was different and the character of alterations depends on genetic heterogeneity. After chronic irradiation in generations in heterogenic line Canton-S since 5 generation cyclic life-span oscillations disappeared, values of median life-span leave on a plateau. Since the 8th generation the life-span values of irradiated populations exceeded all the control values. As a result of the irradiation practically in all generations in isogenic line Oregon-R spa occurs increasing of life-span with the comparing to non-irradiated control. This is possible due to the positive influence of radio-induced heterogeneity on the life-span of isogenic strain. Thus, chronic irradiation led to violation of natural cyclic dynamics of Drosophila life-span in heterogenic strain, discovered in the end 80-s' years by F. Lints and D. Ismaylov. Irradiation of isogenic strain led to increasing of life-span in all generations.

[The genetic effects induced by an irradiation in low doses at Drosophila melanogaster].

This article generalizes the results received by authors in researches of genetic effects of an irradiation for Drosophila. It is supposed, that the main effect of low intensity irradiation is connected with the induced genetic instability on which background the realization of effects of a different direction is possible.

[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.

[Effect of low-dose irradiation on the lifespan in various strains of Drosophila melanogaster].

Drosophila melanogaster strains defective in repair, antioxidant defense, and apoptosis displayed a higher aging rate than the wild-type strains when unexposed to ionizing radiation. Irradiation changed the lifespan depending on the genotype. The lifespan and the functional (neuromuscular) activity, which reflects the "life quality", changed in the same direction. A mechanism was suggested for the remote effect of low-dose irradiation on the lifespan. Since cells with a weakened defense system accumulate lesions and age at a higher rate, their elimination in early ontogeny decelerates age-related changes and decreases the aging rate. In subsequent generations, this somatic stress response (hormesis) is replaced by negative genetic effects at the population level and, consequently, the lifespan decreases.

[The ecology-genetic consequences of chronic irradiation for the populations of the plants and animals].

The modem presentations are considered in the review about the consequences for the genotype of animals and of plants of the chronic action of factors of low intensity. Inoffer is spoken about possible dug the chronic irradiation in small doses in microevolution events.

The mutation frequency of Drosophila melanogaster populations living under conditions of increased background radiation due to the Chernobyl accident.

One of the problems facing the program in the wake of the Chernobyl accident is the estimation of genetic damage to plants and animals. Special attention was directed to studying the influence of radioactive pollutants at the accident site by means of an appropriate test system, using standard genetic subjects. The present study describes such investigations. Levels of persistent genetic damage in natural populations of Drosophila melanogaster found in the vicinity of the Chernobyl accident site were examined from August 1986 to September 1989. Evidence is presented which indicates a relationship between the levels of radioactive pollution resulting from the Chernobyl accident and increasing genetic damage to exposed populations. The possible reasons for the decrease of mutation frequency observed in 1988 and 1989 are also discussed. Furthermore, evidence is presented which suggests that radiosensitive Drosophila mutants may be particularly sensitive indicators of radioactive pollution.

[Longevity of Drosophila after exposure to low doses of radiation and etoposide]. / Issledovanie prodolzhitel'nosti zhizni drozofily posle oblucheniia malymi dozami radiatsii i vozdeistviia étopozidom.

The review of perennial researches of the authors on a problem of radiation-induced aging is presented. From the point of view of radiogenetics it is represented perspective to investigate influence of an exogenous irradiating in small doses on fruit fly with defined mutation by phenotypes, that allows to repute a role of separate genes and mechanisms, controlled by them, in a determination of lifetime. At lines described by differences in pattern of mobile genetical elements, the different reaction to an irradiating explained from the point of view of features of the given mobile elements is found. The processing etoposide in concentration 5 microM on preimaginal stages of line with defects of a reparation (mei-41D5) and hypersensibility to an induction apoptosis (wg1-7, wg7L74, th1 [symbol: see text] th4) results in down-stroke of lifetime. The dominant effect of a gene mei-41D5 in a regulation of etoposide-induced change of lifetime is found. Is exhibited, that at lines with defects proapoptosis of genes reaper and Dcp1, the lifetime after influence, both ionizing irradiating, and inducer apoptosis etoposide is enlarged in comparison with the control.