Molecular Cytogenetic Characterization of C-Band-Positive Heterochromatin of the Greater Long-Tailed Hamster ( < b > < i > Tscherskia triton < /i > < /b > , Cricetinae)

The greater long-tailed hamster (Tscherskia triton, Cricetinae) has a unique karyotype (2n = 28), containing 11 pairs of acrocentric chromosomes with large C-band-positive centromeric heterochromatin blocks. To understand the origin and evolutionary process of heterochromatin in this species, we isolated novel families of chromosome site-specific highly repetitive DNA sequences fromTaqI-digested genomic DNA and then characterized them by chromosome in situ and filter hybridization. TheTaqI-families of repetitive sequences were classified into 2 types by their genome organization and chromosomal distribution: the 110-bp repeated sequence organized in large tandem arrays (as satellite DNA), localized to centromeric C-positive heterochromatin of acrocentric autosomes (chromosomes 1 –11) and submetacentric X chromosome, and the 405-bp repeated sequence that was composed of 30–32-bp internal repeats, distributed in the pericentromeric region on the short arms of X and Y chromosomes. The repetitive sequences did not cross-hybridize with genomic DNA of any genera of Cricetinae (Mesocricetus,Cricetulus, andPhodopus). These results suggest that the 110-bp and 405-bp repeats rapidly diverged in the lineage ofT. triton, evolving in a concerted manner among autosomes and X chromosome and within X and Y chromosomes, respectively. The 110-bp centromeric repeat contained a 17-bp motif in which 9 bases are essential for binding with the centromere-associated protein CENP-B, suggesting th...

Source: Cytogenetic and Genome Research - December 19, 2022 Category: Genetics & Stem Cells Source Type: research