engleski

The evolutionary dynamics of satellite DNAs

In the last few years we have witnessed the publication of complete or nearly complete euchromatic sequence assemblies for many species. However, sequencing projects do not cover entire genomes of eukariotic species taken into analysis. Large heterochromatic segments are missing from published results and they are still unaccessible « black holes» of genomes. Heterochromatin comprises considerable fraction of eukariotic genomes and includes satellite DNAs as dominant components that colocalize with pericentromeric/centromeric regions. Satellite DNAs are tandemly repeated sequences, organized in long, usualy megabase-sized arrays and represent a fast-evolving portion of eukaryotic genome. They show significant rearrangments and sequence divergence even between closely species making entire profile of satDNAs species-specific. In recent reports it has been observed that satellites can be associated with complex organizational features necesesary for the function of eukaryotic genome, such as the formation of heterochromatic compartments important for proper chromosomal behaviour in mitosis and meiosis. Despite extensive literature, very little is known about function-related traits of satellite DNA sequences or about origins and evolutionary constraints imposed on diverse satellites coexisting in genomes. The main question is how and why satellite sequences change so fast in nucleotide sequences and in genome content? I will present our model of satellite evolution which can explain dramatical changes in satellite profiles and predict the mechanism which could drive the choise of satellite variants in the genomes of closely related species.

Satellite DNAs; Evolution

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