Comparative Analysis by Chromosome Painting of the Sex Chromosomes in Arvicolid Rodents

• Published in: Cytogenetic and genome research Vol. 132; no. 1-2; pp. 47 - 54
• Main Authors: Acosta, M.J., Romero-Fernández, I., Sánchez, A., Marchal, J.A.
• Format: Journal Article
• Language: English
• Published: Basel, Switzerland S. Karger AG 01.01.2011
• Subjects: Animals; Arvicolinae; Biological Evolution; Chromosome Painting; Microtus; Microtus agrestis; Original Article; Rodentia - genetics; Sex Chromosomes; Heterochromatin; Sex chromosome evolution; Microtus; Chromosome painting
• ISSN: 1424-8581; 1424-859X
• DOI: 10.1159/000318012

Sex chromosome evolution in mammals has been extensively investigated through chromosome-painting analyses. In some rodent species from the subfamily Arvicolinae the sex chromosomes contain remarkable features such as giant size, a consequence of heterochromatic enlargement, or asynaptic behaviour during male meiosis. Here, we have made a comparative study of the sex chromosomes in 6 arvicolid species using different probes from the X and Y chromosomes of 3 species, in order to gain knowledge about intra- or interspecific preservation of euchromatic regions. Our results clearly reveal poor conservation of the euchromatic region of the Y chromosome within these species, while the euchromatin on the X chromosome is extremely well preserved. Furthermore, we detected no clear correlation between the synaptic/asynaptic behaviour of the sex chromosomes, and the presence or absence of sequence homology within their euchromatic regions. Notably, our study has shown a new relationship between the giant sex chromosomes of 2 species, Microtus agrestis and Microtus cabrerae, that is, both X and Y share a novel region of common sequences in the euchromatin that is not present in the other species analysed. This interspecific euchromatic conservation, limited to the giant sex chromosomes, could point towards a common evolutionary origin for the heterochromatic enlargement process that has characterized the evolution of the sex chromosomes in some arvicolid species.