CHROMOSOME NUCLEOLAR REGION POLYMORPHISM IN LARIX SUKACZEWII UNDER DIFFERENT ECOLOGICAL CONDITIONS
Chromosome nucleolar region polymorphism studies were conducted in Larix sukaczewii growing at the territories of Chelyabinsk Region and Bashkortostan. 5 test areas were analyzed under different ecological conditions, among them one under the conditions of heavy industrial pollution (Zlatoust town), one test areas under the conditions of moderate industrial pollution (Miass town) and three under optimal and control conditions (the settlements of Veselovka, Karaidel, Zilair). The results of the research stated that the average number of secondary constrictions per karyotype in the analyzed test areas was within the limits of 3,42±0,25 до 4,98±0,31, the total number varies from 10 to 16, constant constriction number varies from 1 to 3, non-constant constriction number - from 8 to 13. The highest number of secondary constrictions was observed in test areas under heavy industrial pollution, the middle values were observed in test areas under the conditions of moderate pollutions, the lowest values - under optimal and control conditions. The use of one-strain polynucleotide probe labeled with radioactive isotopes let us determine that the number of 18-25 rRNA gene sites in Larix sukaczewii is equal to 4. On the whole, in the analyzed test areas of Larix sukaczewii there is observed a clear tendency to increasing the number of chromosome nucleolar regions under the conditions of anthropogenic stress. Larix sukaczewii growing under industrial pollution conditions is likely to undergo a considerable pressure of stress factors which leads to activation of latent nucleolar loci, in other words compensatory mechanisms are included for complete genome functioning. In total the obtained results testify to the increase of functional activity of chromosome nucleolar regions in Larix sukaczewii under ecologically unfavorable conditions.