[Variability of the heterochromatic regions of the eukaryotic genome in connection with their possible biological role (based on the example of Drosophila melanogaster)].

Heterochromatin in the genomes of higher eukaryotes carrying repeated DNA sequences comprises up to 30-50% of the total DNA content. Repeated elements (satellites, retrotransposons, and tandemly repeated genes) in heterochromatin of D. melanogaster are considered in respect of their amplification resulting in pronounced biological effects. These elements were coined as "egoistic DNA" whose amplification may be restricted as a result of unknown types of interactions with the host genome. Correlations of the extent of amplification of heterochromatin elements with the fitness of individuals, reproductivity, and capability to transmit to the progeny a chromosome carrying the amplified heterochromatic region are discussed. The possible dependence of the genotypic structure and the fate of population in successive generations on the events of amplification of repeated heterochromatic elements in parental genomes is accentuated. In other words, "intragenomic population processes" driven by the amplification of several types of repeats ("egoistic DNA") must be taken into account when considering the dynamics of biological events in the course of propagation of individuals in a population.