[Genetic effects in plant populations in the zone of the Chernobyl accident].

During 6 years, starting from 1986, the monitoring of the dynamics of the frequency of embryo lethal and of chlorophyll mutations was carried out in arabidopsis populations in areas with different levels of radioactive contamination by the Muller embryo-test in the 30 km of ChNPP. The dose rate of chronic irradiation in the examined areas varied from 0.014 to 17 nA/Kg.

[Genetic effects in populations of plants growing in the zone of Kyshtym and Chernobyl accidents].

Studies to analyze the genetic processes in natural populations of plants were started on the territory of the East-Ural Radioactive Trace (EURT) in 1962 and in the zone of the Chernobyl accident in May 1986. The main directions of the genetic studies in both radioactive areas were similar: 1) study of the mutation process intensity depending on the dose and dose rate and analysis of dose-effect relationships for different genetic changes (point mutations, chromosome aberrations in mitosis and meiosis) in irradiated plant populations; 2) study of the mutation process dynamics in generations of chronically (prolongly) irradiated populations of plants; 3) analysis of microevolutionary processes in irradiated plant populations. The report presents an analysis of observed dose-effect relationships under the action of radiation on populations of Arabidopsis thaliana, Pinus sylvestris and a number of other plant species.

[The cytogenetic effects in natural populations of Crepis tectorum L. growing in the region of the eastern Urals radioactive trace].

Genetic consequences of a prolonged action of ionizing radiation were analyzed in five natural Crepis tectorum populations growing at the radioactively contaminated territory of the East-Ural radioactive track. In these populations about 40 years after the start of a chronic irradiation an increased frequency of chromosome aberrations was found out. An additional acute gamma irradiation at the dose of 20 Gy did not reveal any changes of radioresistance of the plants investigated.

[The cytogenetic effects in Crepis tectorum populations growing in Bryansk Province observed in the 7th year after the accident at the Chernobyl Atomic Electric Power Station].

Cytogenetic analysis of seedlings from the seeds of four populations of Crepis tectorum plants grown during 7 years in localities of Bryansk Province contaminated with radioactive products was carried out. The frequency of chromosome aberrations in root meristematic cells was higher than at similar dose rates within 30-km zone of the Chernobyl NPP. At the same frequency of chromosome aberrations (induced at higher dose rates) karyotypes with pronounced frequency were observed in 30-km zone of the Chernobyl NPP.

[The cytogenetic effects in natural populations of Crepis tectorum exposed to chronic irradiation in the region of the Chernobyl Atomic Electric Power Station. An analysis of the frequency of chromosome aberrations and karyotype changes in the 3rd and 4th years after the accident].

In three natural Crepis tectorum populations from 30-km zone of the Chernobyl NPP cytogenetic analysis of plant progenies was carried out. Germination capacity was not correlated with the dose rate of chronic irradiation. There was a correlation between frequency of cells with chromosome aberrations and frequency of seedlings with non-identical altered karyotype among which pericentric inversions and reciprocal translocations dominated.

[Cytogenetic analysis of first two mitoses in the root meristem of stored for a prolonged time period Crepis tectorum seeds subjected to chronic irradiation in the 30-kilometer zone of the accident at the Chernobyl Atomic Power Plant].

Seeds of Crepis tectorum natural populations 1 and 3 subjected to chronic irradiation in 1986 during 4 months in 30-kilometers zone of Chernobyl were stored for 6 years in a laboratory. In 1993 a method of continuous germination of seeds in 0.01% colchicin solution was used and an analysis of chromosome aberrations in the first tetraploid cells was made as it was done in 1987 just after finishing of a dormant period of seeds.

[The cytogenetic effect in the seeds from natural Crespis tectorum populations in long-term storage subjected to chronic irradiation as a result of the radioactive pollution in a 30-kilometer area of the accident at the Chernobyl Atomic Electric Power Station].

Seeds of the 1st and 3d Crepis tectorum natural populations subjected to chronic irradiation during 4 months in 1986 within 30 km zone of Chernobyl accident were stored for 5 years in laboratory. For this period germination capacity of 1st population seeds decreased but the seeds retained a germination capacity up to 1992 were characterized by the increased germination rate. The germination capacity and the germination rate of 3d population seeds did not change.

Cytogenetic effects of ionizing radiation in Crepis tectorum growing within 30 km of the Chernobyl atomic power station.

Cytogenetic effects of chronic irradiation in Crepis tectorum populations growing within 30 km of the Chernobyl atomic power station were determined by scoring the frequency of chromosome aberrations in first-mitosis-metaphases of root meristematic cells during seed germination. In the first year after the accident there were large differences in the distributions of radionuclides on the plots where the three studied populations were growing. Gamma-irradiation exposure rates were in the range 5-10 mR h-1 (beta-irradiation exposure rates were about 10 times higher).

[Cytogenetic effects in native populations of Crepis tectorum exposed to chronic irradiation in the vicinity of the Chernobyl Nuclear Power Station. Induction of chromosome aberrations during the first 2 years following the accident].

During the first year after the accident the maximum frequency of Crepis tectorum cells with chromosome aberrations amounted to 10.2 to 15.3% at a dose-rate of 5-10 mR/h (gamma-radiation), cells with multiple aberrations being rather frequent.

[The cytogenetic effect of chronic irradiation revealed using an analysis of the first two mitoses in the root meristem of germinating seeds of Crepis tectorum from the 30-kilometer zone of the accident at the Chernobyl Nuclear Power Station].

Peculiarities of the appearance of C. tectorum rootlet in the course of seed germination have prompted the authors to use the method of continuous germination of seeds in 0.01% colchicine solution and to analyze chromosome aberrations in the first tetraploid cells derived from early dividing cells.

[Growth of Arabidopsis thaliana embryos following irradiation of the plants during the generative phase].

The flowers and young legumes of Arabidopsis thaliana (phases of development B3--B7) were irradiated by gamma-rays at the dose of 4 kr. The irradiation did not influence the duration of phases of the flower development irrespective of the phase of irradiation. The cytological characteristics of embryos is given for each phase under study.