engleski

Complex structural features of satellite DNA sequences in the genus Pimelia (Coleoptera: Tenebrionidae): random differential amplification from a common "satellite DNA library"

The major satellites of the nine species of the subgenera Pimelia s. str. and Amblyptera characterised in this paper are composed of longer monomers (500 and 700 bp) than those described previously in 26 Pimelia s. str. taxa (357 bp). Sequence analysis reveals partial similarity, although marked divergence, among these satellites and with respect the monomers of the PIM357. The discrepancy between the phylogeny obtained based on two mitochondrial and two nuclear markers and the one deduced from stDNA sequences suggest that the different Pimelia satellites were already present in a common ancestor forming what has been called a satellite DNA library. Present satellite profiles result from a random amplification of satellites during diversification of the species. However, species-specific turnover have occurred at different rates: either abrupt replacements, gradual divergence or with no apparent change for a long evolutionary time. Results also point to a common evolutionary origin of all Pimelia satellite sequences involving several rearrangements. We propose that the repeat unit of about 500 bp has originated from the insertion of a 141 bp-long DNA fragment in the PIM357 unit. The 705 bp repeats have originated in a 32 bp direct duplication and the insertion of a 141 bp in inverted orientation with respect to the basic structure of of 533 bp.

satellite DNA; Pimelia; Coleoptera; repeat unit rearrangements

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