Features of the mitotic activity of cells of Scots pine exposed to chronic ionizing radiation
The purpose of work was the study of variability in mitotic activity of the tissues of Scots pine in various areas, including the Exclusion Zone, Chernobyl NPP Southern non-black earth area of Russia. Sample plots (PP) are located on the South non-black earth area with different levels of radioactive contamination. We calculated the mitotic index (MI) and determined the relative duration of the phases of mitosis based on the number of cells in a specific phase of mitosis. Effects of ionizing radiation increases the rate of cell division – MI grows. The minimum value of MI (6.64 %) was observed in the controls, the experimental variants, it was increased. Increase of DER changed the duration of phases of mitosis, i.e. the number of cells in the individual phases. There was no significant effect of exposure dose rate (EDR) on the number of cells at metaphase and anaphase. In general, with increasing EDR rate of cell division (MI) increases. The number of cells in prophase stage, with increasing EDR increases and telophase decreases, except version with the highest EDR. Background radiation does not change the duration of metaphase and anaphase. In the stage of anaphase we recognized various chromosome abnormalities: bridges, fragments, chromosomes yields ahead, their backlog, and simultaneous yields and gap. The experimental results showed that the Scots pine plantations have significant impact of chronic ionizing radiation: mitotic activity of cells increased, the number of cells in prophase increased, the number of anaphases with bridges, with a yield of chromosomes (at the highest EDR), with a gap, and simultaneous yield and gap, duration of metaphase and anaphase is not modified, telophase is reduced, in a small number the anaphase with fragments are marked.