Interstitial telomeric repeats as markers of evolutionary changes in the mammalian karyotype: Human chromosome 2

The presence of conserved telomeric repeats represented by the hexamer (TTAGGG)n at the chromosomal termini is necessary for the correct functioning and stability of chromosomes. A number of the genomes of mammals, including human, are known to contain interstitial telomeric sequences located far from the chromosomal termini. It is assumed that these repeats mark the regions of fusions or other rear-rangements of ancestral chromosomes. Exact localization of all interstitial telomeric sequences in the genome could significantly advance the understanding of the mechanisms of karyotype evolution and speciation. In this context, software was developed to search for degenerate interstitial telomeric repeats in complete sequences of mammalian chromosomes. The evolutionary significance of such repeats was demonstrated by the example of human chromosome 2. The results are available at http://www.bionet.nsc.ru/labs/theorylabmain/orlov/telomere/.