engleski

Origins and evolution of satellite DNAs: the nematode view

The noncoding DNA sequences repeated in tandem, satellite DNAs, compose significant portion of every eukaryotic genome. Despite tremendous advances in sequencing and assembly of genomic DNA, satellite repeats are underrepresented in outputs of genome projects, which are still focused on non-repetitive, gene-rich euchromatic segments. However, more and more attention is given to the noncoding genomic fraction, because it gives an organizational framework to every eukaryotic genome, underlies pivotal genomic functions and may represent a major trigger in speciation. Unlike the coding part, satellite DNA vary greatly in size and sequences even in closely related species and this extreme diversity raised difficulties in deriving general conclusions about the origin, evolution and function of satellite DNA in higher organisms. The study of satellite DNAs in closely related species contributes to the understanding of satellite DNA evolution and dynamic processes that structure eukaryotic genomes. Moderate abundance of different satellite repeats, parthenogenetic mode of reproduction, defined phylogenetic relationships and available source of genome sequencing data make RKN species a good model system to study satellite DNAs. The overview of our present studies on a group of Meloidogyne species will be presented. In particular, the results obtained relate stochastic processes and selective pressure in the evolution of satellite DNAs, explain the origins of different forms of satellite DNAs coexisting in genomes in the form of a common library, and establishes genomic composition of satellite DNAs as a phylogenetic marker capable to help in resolving some questions in RKN species evolution. Although concluded on a limited sample of RKN species, we suggest that obtained information describes general behavior characteristic of all satellite DNAs.

nematode; nekodirajuće DNA sekvence

nije evidentirano