engleski

The role of satellite DNA in insect genome regulation and evolution

Satellite DNAs are major building elements of pericentromeric and centromeric heterochromatin in many eukaryotes. In some species they account for the majority of genomic DNA as in beetles from the coleopteran family Tenebrionidae, where they comprise more than 50% of the whole genomic DNA. In addition to participating in heterochromatin and centromere formation, satellite DNAs are also proposed to perform a gene-regulatory function and to play a role in genome evolution. In beetle Tribolium castaneum (Coleoptera) satellite DNA sequences as the major heterochromatin constituents play important role in heterochromatin regulation and remodelling during development and environmental stress response. Satellite DNA expression is strongly induced by heat shock, and increased level of satellite-derived small interfering RNAs (siRNAs) is accompanied by increase of repressive epigenetic modifications of histones at satellite DNA regions. In addition to their presence in the heterochromatin, short stretches of satellite DNA have been mapped in the close vicinity of numerous genes within euchromatin. Dispersed satellite repeats are statistically overrepresented near protein-coding genes with immunoglobulin-like domains attesting to their non-random distribution. The environmentally susceptible transcription of satellite DNAs from the internal promoters as well as their distribution close to protein-coding genes provides strong support for their role in genome regulation and adaptation to different environmental conditions. In addition, parallel presence of satellite DNA elements within heterochromatin and euchromatin indicates the direct cross-talk between the two structurally and functionally different genomic regions.

satellite DNA; gene regulation; siRNAs; genome evolution; adaptation

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