title: Comparative analysis by chromosome painting of the sex chromosomes in arvicolid rodents.
abstract: 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.
authors.affiliation: Departamento de Biología Experimental, Facultad de Ciencias Experimentales, Universidad de Jaén, Jaén, Spain.
authors.forename: M J
authors.initials: MJ
authors.lastname: Acosta
authors.forename: I
authors.initials: I
authors.lastname: Romero-Fernández
authors.forename: A
authors.initials: A
authors.lastname: Sánchez
authors.forename: J A
authors.initials: JA
authors.lastname: Marchal
mesh_terms: D000818:Animals; D005075:Biological Evolution; D020223:Chromosome Painting; D012377:Rodentia / Q000235:genetics*; D012730:Sex Chromosomes