Chromosome and aging: genetic conception of aging.

The mutation level (chromosome aberrations covering telomere regions), modifications of chromosome structure (level of condensed chromatin identified by the methods of electron microscopy and differential scanning microcalorimetry; level of C-banding constitutive heterochromatin; transcriptional activity of DNA-dependent RNA polymeraze; Ag-positive NORs and associations of acrocentric chromosomes) and reparation (intensity of unscheduled DNA synthesis and the frequency of sister chromatid exchanges) have been studied in lymphocyte cultures from individuals at the age of 72-114 to reveal the chromosome functional organization at late stages of ontogenesis and to find explanations of some senile pathologies. The analysis of obtained results showed: 1. Chromosome progressive heterochromatinization (condensation of eu- and heterochromatin regions) occurs at aging; 2. Decrease of repair processes and increase in frequency of chromosome aberrations in aging are secondary to the progressive heterochromatinization. Chromosome heterochromatinization is a key factor of aging; 3. Chromosome heterochromatinization may be the reason for some senile pathologies; 4. Chromosome heterochromatinization is an area where one should seek the ways for prolonging the lifespan.