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Analysis of materials from long-term studies characterizing the current state of sturgeon stocks in the Volga-Caspian fisheries basin, and the dynamics of commercial catches of beluga, sturgeon and stellate sturgeon in the XX – XXI centuries indicates that the Northern Caspian occupies the leading value in catch volumes, where more than 70 % of sturgeon fish are annually harvested. In the first half of the twentieth century sturgeon stocks were determined by the scale of natural reproduction in rivers and fishing volumes; in the second half, natural and anthropogenic factors began to intensively influence the formation of sturgeon stocks. The development of hydraulic construction on rivers, an increase in the withdrawal of freshwater runoff, a decrease in sea level to –29.0 mBS, pollution by industrial and agricultural runoff have necessitated the development of a set of measures for the reproduction, conservation and rational use of the Caspian’s aquatic biological resources. As a result of the studies, the response of the sturgeons to the changed conditions of reproduction has been determined in order to restore and increase their commercial stocks; high ecological adaptability of sturgeons to various living conditions within their range, their exceptional plasticity and pronounced intraspecific differentiation have been established. These indicators point to the possibility of creating conditions that meet the requirements for water quality for the life of sturgeons during migration and reproduction. In the course of the analysis of the obtained data, the influence of regulation of the Volga River flow on the efficiency of natural reproduction of sturgeons has been evaluated; the role of industrial sturgeon breeding in sturgeon stock formation has been shown; the abundance of juveniles in the North Caspian and adult individuals on feeding pastures of the sea has been estimated; trends in the number of sturgeon producers migrating in the Volga to spawning sites have been identified; the prospects for the restoration and rational use of sturgeons in the Volga-Caspian basin have been determined.

Parameters related to 90Sr mobility in the soil-plant system are reported: exchangeable content, selectivity coefficient, and transfer factor. Large mobility of 90Sr in different soil types was shown. The fraction of exchangeable 90Sr varied between 70 and 90%. The selectivity coefficient K(C)(90Sr/Ca) values were in the range 1.3-2.5. The radionuclide transfer factors (TF) varied by a factor of 9.6 for barley seedlings and by a factor of 6.6 for lupine seedlings. The exchangeable Ca content was the determinant soil parameter responsible for differences in 90Sr biological availability. A static model was devised that describes 90Sr sorption from soil solution by soil and on the root surface. The parameter of 90Sr bioavailability (A) has been suggested. Parameter A was calculated from data on soil exchangeable Ca content and 90Sr mobility indicators--exchangeable fraction of the radionuclide and the selectivity coefficient K(C)(90Sr/Ca). A correlation was found between TF and parameter A.

137Cs vertical migration in boggy soils has been studied 15 years after the Chernobyl accident. The rate of vertical migration of the radionuclide is shown to be dependent on the peculiarities of formation of peatbogs, their moistening regime and soil properties. 137Cs migration in a high-land peatbog is characterized by higher intensity then in lowland or transitional peatbogs. Differences in 137Cs vertical migration are to a large extent caused by the contents in soil of exhangeable and mobile radionuclide forms. The derived experimental data that describe 137Cs distribution over the profiles of peaty soils of different type are used for parameterization of two-component convective-diffusion model. Ecological and effective half-life periods of 137Cs content reduction in the soil root layer have been calculated. A long-term prediction is given of the dynamics of the radionuclide content in the root layer of peaty soils.

Chronic irradiation of sheep with doses of 2.6 and 12.9 mC.kg was characterized by the modification of the adenylatecyclase activity and Ca2+ permeability of plasma membrane in cells of the peripheric blood, with no changes in the clinical and hematological indicators. The observed effects are assumed to result from structural and dynamic variations in the lipids of membranes.

Enhancing stimulation effect of prostaglandin E1 on adenylate cyclase, decrease in basal activity of adenylate cyclase in platelets and reducing thyroxine concentration in cow plasma 5 years after radioiodine damage to thyroid gland with doses higher than 200 Gy were detected, whereas only decrease in adenylate cyclase activity in platelets from animals irradiated with 40 Gy to thyroid gland was observed. No changes in platelet adenylate cyclase in cows exposed to less than 1 Gy to thyroid gland after 5 years of maintenance on the territory with 137Cs contamination density lower than 0.37 MBq/m2 were found.

It was found that the total Ca content in erythrocytes from irradiated sheep and horses increased by 10-40% from 1st till 5th days after irradiation, the intracellular Mg content being unchanged. More than 2-fold increase in total Ca content in lymphocytes during first 15 days was revealed, while in platelets only a trend for a growth in acute period of radiation disease was detected. On the contrary, no reliable changes in total Ca content in plasma after irradiation were observed. This fact indicates that Ca accumulation in blood cells after whole-body irradiation is due to disturbance in intracellular Ca(2+)-homeostasis.

The immunoreactive calmodulin content was shown to increase in the irradiated platelets of rats and cows. Total Ca content did not vary significantly in platelets of exposed animals although there was a tendency toward its increase. At the same time, total Ca content in lymphocytes of irradiated cows increased while the immunoreactive calmodulin level remained unchanged.