Repeated DNA sequences as an engine of biological diversification

Abstract

Several aspects of the functional role of non-protein-coding DNA elements in the cell life and taxa evolution were discussed in connection with modern views on three-dimensional regulatory network as a basis for life support and evolution. In accordance with this problem, the leading role of duplication and multiplication of any DNA fragments (from single nucleotides to segmental duplications) in origination of genome structure and reshaping were considered in relationships with chromatin proteins. By this way the diversities in genome and chromosome architectonics leads to diversity of morphogenesis. The regulation and plasticity of the genome is determined by the structure, plasticity and evolution of genomic satellite and dispersed repetitive elements, which, being tightly bound with life phylogeny, result in somatic and inherited changes. Repeated sequences take part and perform some epigenetic regulation via repeats themselves, their modifications, or via their RNA transcripts. There is a growing evidence that the usage of methaphoric designations of protein-noncoding sequences as "egoistic, junk or parasitic" are senseless and useless. To the contrary, the hypothesis is formulated that the repetitive non-coding DNA part could be considered as a main substrate of life, something like a "carcass" serving as a basis for protein-coding sequences. The own molecular evolution of this carcass defines the pattern of DNA transcription and then evolution of structural proteins and morphological differentiation. Genes involved in main energetic, "house-keeping" and metabolic processes are forming some kind of the protecting envelope for the hereditary material, and also provides the enzymatic pathway of replication, transcription and epigenetic regulation.