engleski

Characterization of a subtelomeric satellite DNA in the mollusc Donax trunculus

Satellite DNAs are non-coding, tandemly repeated DNA sequences that comprise long arrays in the genome and are usually located within heterochromatic regions of chromosomes. Among marine invertebrates, satellite DNAs have so far been studied in detail only in a couple of taxonomic groups. We detected a novel satellite DNA present in the genome of the bivalve mollusc Donax trunculus. The monomer repeat length of this satellite is 169 bp, while the sequence analysis reveals high sequence conservation maintained throughout the entire monomer length. In contrast to the other satellites detected previously in the genome of D. trunculus (Petrovic and Plohl, Gene 2005, 362:37, and references therein), this is a GC rich satellite that has also been shown to exhibit CpG site methylation. In addition, this is the most abundant (5 %) among all detected satellites. Fluorescence in situ hybridization revealed that this satellite is located in subtelomeric regions on more than half of D. trunculus chromosome pairs. Its location on a subset of chromosomes and homogeneity of randomly cloned variants indicate different homogenization mechanisms acting between chromosomes, and/or different evolutionary history of chromosomes in the D. trunculus genome.

repetitive sequences; concerted evolution; heterochromatin; FISH

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