[Potential relationship between mutation process induced by low doses of ionizing radiation, and positional dynamics of chromosomes in nuclei of eukaryotic cells].

The mutation process has many stages. The information presented in this article suggest that a cell exposed to low LET radiation in the low-dose range (up to 1 cGy) must almost completely repair all spontaneous and radiation-induced DNA lesions. But reparation of DNA double-stranded breaks (DSB), which are the basis of genome instability has peculiarity. We have shown that the mechanisms of action of low doses (which initiate natural antimutagenic reactions of resting cells--an adaptive response) are associated with chromosome loci (centromere) movement in a cell nucleus. We suggest that the movement of chromosome loci in cell nucleus is the fundamental mechanism for repair of DSB and switching of the transcription of gene (it is known that in case of lymphoid cells Ikaros-complexes repressor is colocolizated with centromere loci); in particular, of nucleolar transcription activities because the latter is dependent on centromere arrangement. Because the movement of chromosome loci in both the mitotic cycle and under adapting dose on resting cells is much the same it could be assumed that in latter case the cells also lose their functional characteristic for differentiated resting cells. Under chronic exposure to low doses the functional changes can be the cause of organic changes if adapting dose affects the sufficient part of the cells. The role of cells of evolutional or ontogenetic reserve in mutation process is considered.