[Spatial organization of the eukaryotic genome and the action of epigenetic mechanisms].

Genome activity in eukaryotic cells is regulated at different levels. Long-term activation and repression of gene expression is controlled by epigenetic mechanisms. The main feature of epigenetic mechanisms is that regulatory events, provided by these mechanisms, are preserved in a series of cellular generations upon mitotic division, i.e., in a certain sense are inherited. Most of the epigenetic mechanisms, known so far, act at the level of nucleosomes and the dynamics of nucleosomal fibre. The important signal elements of epigenetic system are DNA methylation, histone modifications, and the inclusion of noncanonical forms of the histones in nucleosomes. In the present study, we substantiate the statement that the large-scale spatial organization of the DNA in eukaryotic cell also plays an important role in the action of epigenetic mechanisms.