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

• Published in: Cytogenetic and genome research Vol. 162; no. 6; pp. 323 - 333
• Main Authors: Kamimura, Eikichi, Uno, Yoshinobu, Yamada, Kazuhiko, Nishida, Chizuko, Matsuda, Yoichi
• Format: Journal Article
• Language: English
• Published: Basel, Switzerland 01.04.2023
• Subjects: Animals; Base Sequence; Centromere - genetics; Cricetinae; DNA; DNA, Satellite - genetics; Heterochromatin - genetics; In Situ Hybridization, Fluorescence; Karyotyping; Original Article; Repetitive Sequences, Nucleic Acid - genetics; CENP-B box; Repetitive DNA sequence; Centromeric/pericentromeric heterochromatin; Concerted evolution; Nucleotide sequence conservation
• ISSN: 1424-8581; 1424-859X
• DOI: 10.1159/000527478

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 from TaqI-digested genomic DNA and then characterized them by chromosome in situ and filter hybridization. The TaqI-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, and Phodopus). These results suggest that the 110-bp and 405-bp repeats rapidly diverged in the lineage of T. 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 the possibility that the 110-bp major satellite DNA carrying the 17-bp motif may have a role in the formation of specified structure and/or function of centromeres in T. triton.