Non-random inactivation of the X-chromosome in interspecific hybrid voles

Abstract

Expression of X-linked genes for G6PD and GALA in interspecific hybrids between Microtus arvalis, M. subarvalis and M. kirgisorum voles was studied. Quantitative predominance of the enzyme activities of M. arvalis over G6PD activity of M. subarvalis and the GALA activity of M. kirgisorum in the female hybrids was shown. The definitive patterns of these enzyme activities was found on day 6·5 of embryonic development. Non-random inactivation of X-chromosomes derived from M. subarvalis and M. kirgisorum in the interspecific hybrids with M. arvalis is supposed to be the cause of the phenomenon observed. A hypothesis is proposed that there is a connection between the presence of large heterochromatin regions in the X-chromosomes derived from M. subarvalis or M. kirgisorum and the preferential inactivation of these in female hybrids with M. arvalis. © 1987, Cambridge University Press. All rights reserved.