Comparative analysis of DNA homology in pericentric regions of chromosomes of wood mice from genera Apodemus and Sylvaemus

Abstract

In the present study, an analysis of the DNA homology of the pericentric chromosomal regions and pericentric heterochromatin in distantly related species of wood mice (species from the Apodemus genus, as well as from the Apodemus and Sylvaemus genera) was conducted by fluorescent in situ hybridization (FISH) with microdissected DNA probes obtained from the corresponding chromosomal regions of these species. Cross-hybridization of microdissected DNA probes obtained from pericentric C-positive blocks of chromosomes of Sylvaemus species with chromosomes of Apodemus species, as well as DNA probes from pericentric C-positive blocks of chromosomes of Apodemus species with chromosomes of Apodemus and Sylvaemus species, showed that DNA repeats homologous to the pericentric regions in other species represented. dispersed repeats in C-negative chromosomal regions, as well as in several regions bordering pericentric C-positive and C-negative regions in heterochromosomes and autosomes and in distal regions in the long arms of several autosomes. The results indicate that the level of DNA homology in pericentric chromosomal regions decreases with an increase in the differentiation level and a decrease in the kinship between the compared forms and species of wood mice. Most likely, degeneration of the DNA repeats is accompanied by a gradual destruction of repeat clusters and their replacement by new, nonhomologous repeats in almost all pericentric regions (some old repetitive sequences might be "extruded" into interstitial or telomeric regions of chromosomes). These processes, which are observed in some species from Sylvaemus genus in distantly related species of Sylvaemus and Apodemus genera, have almost achieved the final stages.