[Genotype dependence of cytogenetic and epidemiological characteristics in the liquidators of the accident at the ChNPP].

The dependence of the level of unstable chromosome aberrations and nononcological diseases on the genotype in 57 liquidators of the ChNPP accident was studied. Candidate genes presumably affecting radiosensitivity were highly polymorphic loci of xenobiotic detoxication genes (glutathione-S-transferases GSTM1, GSTT1, GSTP1) and the 5,10-methylenetetrahydrofolate reductase gene (MTHFR) involved in DNA methylation and synthesis. An increased frequency (0.014 +/- 0.001 per cell) of unstable chromosome aberrations, including radiation-specific dicentrics and centric rings (0.0015 +/- 0.0002 per cell), has been found to be preserved in the group of liquidators examined in 2006-2007. No associations of polymorphism for each of the studied genes with cytogenetic parameters were revealed. Increased frequencies of chromosome aberrations were recorded in homozygous carriers of a deletion at the GSTM1 locus in combination with homozygosity for minor alleles at the MTHFR and GSTP1 loci (p = 0.00002 and p = 0.0233, respectively). The number of homozygous carriers of the minor allele GSTP1 was increased among patients with chronic obstructive pulmonary disease and in liquidators with acute circulation disturbances (p = 0.014 and p = 0.04, respectively). Double homozygotes for GSTM1 and GSTT1 deletions were significantly more frequent among subjects with benign tumors (cysts, polyps, p = 0.015) and with benign thyroid tumors (p = 0.017). This genotype has proved to be protective for patients with severe cardiovascular diseases (acute circulation disturbances, p = 0.027).

[Cytogenetic effects in plant populations from the East Urals Radioactive Track]. / Tsitogeneticheskie éffekty v populiatsiiakh rastenii, proizrastaiushchikh na Vostochno-Ural'skom radioaktivnom slede.

Mutation dynamics in generations was studied in natural populations of plants from the East Ural Radioactive Track (EURT, Kyshtym accident). The experiments were aimed at the investigation of the formation of genetic load in natural plant populations under conditions of prolonged radiation exposure. The main approach used in the study was the analysis of cytogenetic alteration, chlorophyll and gene mutations in plants exposed for more than 40 years to chronic beta-irradiation and in their progeny.

[The cytogenetic effects in the population of the Altai Territory subjected to ionizing radiation exposure as a result of the nuclear explosions at the Semipalatinsk proving grounds]. / Tsitogeneticheskie éffekty u naseleniia Altaishogo kraia, podvegshegosia vozdeistviiu ioniziruiushchikh izluchenii v rezul'tate iadernykh vzryvov na Semipalatinskom poligone.

The cytogenetic examination of 178 persons living in seven settlements of the Altai region exposed to ionizing radiation during Semipalatinsk nuclear tests in 1949-1962 was carried out. It was shown that more than 80% of absorbed dose was due to the first nuclear explosion in 1949. The frequency of chromosome aberrations (dicentrics and rings) significantly exceeded the control level. The linear correlation between the dicentrics and rings frequency and absorbed dose was found. The cells with more than one aberrations were revealed in irradiated persons. This is supposed to be the result of 239Pu alpha-radiation.

Radiobiological experiments with plant seeds aboard the biosatellite Kosmos 1887.

The effects of spaceflight factors on the seeds of Arabidopsis thaliana and Crepis capillaris were studied provided with various protective measures: the seeds were located inside the satellite and in open space, protected with aluminium foil and also exposed without the foil cover. When the seeds were in open space without any protection, their viability was found to be suppressed; the survival rate and fertility of plants grown from these seeds were also diminished. An increase in the frequency of chromosome aberrations (CA) and in the number of multiple injuries was registered in this case. Experiments with the aluminium foil shielding showed a decrease in the suppression of the seeds' viability, but mutational changes were found to be even more increased, while the survival and fertility of the plants decreased. An increase in the thickness of shielding resulted in a decrease in the effects up to the level of the control, except for the effects connected with CA and fertility of the plants. Analysis of the results shows that these impairments can be ascribed to the action of single heavy charged particles (HCP). The seeds can be thus regarded as an integral biological 'dosimeter' which allows estimation of the total effects of radiation, ecological and biological factors.

[Experiments with growing plants on orbital stations Saliut-5, Saliut-6 and Saliut-7]. / Eksperimenty s razvivaiushchimisia rasteniiami na orbital'nykh stantsiiakh "Saliut-5", "Saliut-6" i "Saliut-7".

The experiments with air-dry Crepis capillaris seeds flown on the spacecraft Soyuz-16 and orbital stations Salyut-5, Salyut-6 and Salyut-7 showed that the number of aberrant cells in the seedlings grown during flight (experimental) and after flight (flight control) was higher than that in the ground-based control. This number was greater in the experimental seedlings than in the flight controls. The plants Arabidopsis thaliana grew from cotyledons to flowers during flight. The seeds developed postflight exhibited a lower fertility and a higher frequency of recessive mutants (Experiment Svetoblock-1). The greater number of mutants persisted in the progeny of plants that completed their developmental cycle (Experiment Phyton-3). Inhibited viability of germs manifested as a reduced germination rate of flown seeds and a premature death of seedlings. In the first postflight generation the lesions produced by large chromosome aberrations were eliminated and the lesions caused by gene mutations and micro-aberrations were retained.

Experiments with air-dried seeds of Arabidopsis thaliana (L) Heynh. and Crepis capillaris (L) Wallr., aboard Salyut 6.

Space flight factors resulted in the accumulation of genetic damage in embryonic meristem cells of seeds of Arabidopsis thaliana and Crepis capillaris in flights of different duration (49, 226, 408 and 827 days) aboard the orbital station Salyut 6. As a result, the viability of seeds and seedlings was reduced, and the sterility of plants grown from seeds exposed on Salyut 6 was increased. The effect depended upon the flight duration. The data obtained suggest an acceleration of seed aging under flight conditions.

The role of weightlessness in the genetic damage from preflight gamma-irradiation of organisms in experiments aboard the Salyut 6 orbital station.

The effect of weightlessness on chromosomal aberration frequency in preflight irradiated Crepis capillaris seeds, on the viability, fertility and mutation frequency in Arabidopsis thaliana, and on the frequency of nondisjunction and loss of X chromosomes in pre-flight irradiated Drosophila melanogaster gametes was studied aboard the Salyut 6 orbital station. The following effects were observed: a flight-time dependent amplification of the effects of preflight gamma-irradiation in A. thaliana with respect to all the parameters studied; unequal effects in seeds and seedlings Crepis capillaris; and a significant increase in the frequency of nondisjunction and loss of chromosomes during meiosis in Drosophila females. These observations are discussed in terms of the data of ground-based model experiments and flight experiments with a different time of exposure of objects to weightlessness. An attempt is made to elucidate the role of weightlessness in the modification of ionizing radiation effects.

The action of space flight factors on the radiation effects of additional gamma-irradiation of seeds.

The action of space flight factors (SFF) on radiosensitivity and the effects of preflight irradiation of air-dried Crepis capillaris (L) Wallr and Arabidopsis thaliana (L) Heynh seeds aboard the spaceships of the Cosmos, Soyuz and Salyut series was studied. The results have shown that vibration and linear acceleration (VA) cause damage of the meristematic embryonic cells and simultaneously decrease the radiosensitivity of seeds. SFF enhance the effect of preflight gamma-irradiation of seeds with respect to a number of characteristics. This can be explained partly by the action of VA. The basis of all observed effects is chromosomal aberrations which are expressed in a series of successive cell divisions and which decrease the survival and fertility of plants that grow from flight-exposed seeds.

Biological investigations on the orbital station "Salyut-5".

Genetic and embryological investigations were continued on the orbital station Salyut-5. The effect of space flight factors on dry Crepis capillaris (L) Wallr seeds and seedlings, dry Arabidopsis thaliana (L) Heynh seeds, Polyporus brumalis Pers. ex. Fries culture as well as on spawn development and fish behaviour was studied. Space flight factors are shown to have adverse effects with respect to some characteristics in seeds and seedlings, and to change the morphology of the fungus. Fishes appear to adapt themselves to weightlessness.

Biological investigations of higher and lower plants aboard Soyuz 19.

Biological investigations carried out aboard Soyuz 19 consisted of three independent complex experiments. All biological materials aboard the spacecraft were kept in "Biocat" thermostats which maintained the required temperature. The objective of the experiment "Genetic investigations" was to determine the effect of space flight factors on the heredity of lower (Chlamydomonas reinhardi Dang) and higher (Crepis capillaris (L) Wallr and Arabidopsis thaliana (L) Heynh) plants, and on the radiosensitivity of plant seeds and the radiation effect of prior gamma-irradiation. The space flight factors decreased the survival of Chlamydomonas cells and A. thaliana plants of the first generation. They decreased the germination of seeds, increased the rate of chlorophyll mutations and embryonal lethals, produced no effect on the rate of visible mutations in unicellular algae, increased the rate of chromosome aberrations in root meristem cells C. capillaris, induced disturbances in mitosis of unicellular algae and modified the effect of prior gamma-irradiation. The experiment "Growth of micro-organisms" was conducted with a culture of Proteus vulgaris in a growth chamber. After return to the laboratory the experimental and control variants were studied for twenty-two tests. The control and experimental material differed in the average cell size, biomass distribution, the character of haemotaxis, the rate of cell migration over the substratum surface, dehydrogenase activity, ribosomal aggregation, and ultrastructural peculiarities of cells. The experiment "Embryological investigations" was carried out to study the effect of space flight factors on embryogenesis of the bony fish Brachyodanio rerio. No abnormalities were noted in the course or rate of the development of spawn cultivated in a special thermostat.

Cytogenetic analysis of seeds of Crepis capillaris (L) Wallr. exposed on board the earth artificial satellite Cosmos 613.

We studied the effect of space flight factors on air-dry seeds of Crepis capillaris (L) Wallr. and on radiation injury of seeds exposed to gamma-radiation (3 kr, 525 r/min) before and after the flight on the satellite Cosmos 613. Space flight factors induced little increase (which was statistically insignificant) in the rate of chromosome aberrations in cells of the root meristem of Crepis capillaris sprouts, but they enhanced the effect of preliminary irradiation of seeds and decreased their radiosensitivity. The modification of radiation injury was statistically significant.

Modifying effect of dynamic space flight factors on radiation damage of air-dry seeds of Crepis capillaris (L) Wallr.

The influence of dynamic factors (vibration and linear acceleration) on the rate of chromosome aberrations in Crepis capillaris was studied. The vibrational process simulated was similar in its characteristics to that occurring at the launch of spaceships. In combination with linear acceleration it caused a statistically significant increase in the rate of chromosome aberrations compared with the control (R=7.70). The dynamic factors modified the effect of radiation damage induced by acute gamma-irradiation (3 krad). Pre-radiation treatment with vibration and acceleration on the seeds caused a significant decrease (R=10.23) of the effect of radiation damage, from 15.57% to 9.74%. The post-radiation treatment of C. capillaris seeds with the dynamic factors did not change the rate of chromosome aberrations significantly (from 15.57% to 15.90%).

Effects of space flight factors on the heredity of higher and lower plants.

The effects were studied of a long-term space exposure (72 days) aboard the Salyut orbital station on the following: dry seeds of Crepis capillaris (L.) Wallr. and Arabidopsis thaliana (L.) Heynh, haploid and diploid strains of Saccharomyces cerevisiae mutant for adenine locus (ad) and strain LARG-I of Chlorella vulgaris Beijer. A modifying effect of space factors on radiobiological action of gamma-irradiation from 137Cs was determined with the higher plant seeds and Chlorella culture. For this, the material was partly irradiated prior to, and partly after the flight at doses of 3, 30 and 10 kr for C. capillaris, A. thaliana and Chl. vulgaris, respectively. It was shown that: (1) Space factors caused reduced survival of Arabidopsis seedlings and Chlorella and yeast cultures, reduced productivity of Chlorella cells, increased mutability of Chlorella and yeast cells and increased frequency of chromosome aberrations in cells of Crepis root meristem. There are, however, a few exceptions: cell germination of C. capillaris was enhanced while mutability of A. thaliana seeds declined. (2) Space factors increased the adverse effects of the pre-flight irradiation on all the parameters of the cultures tested. (3) Space factors had no genetic effect on the objects tested. They have, however, caused a stronger inhibition of seed germination and augmenting survival of A. thaliana seedlings and Chlorella cells.