Non-random inactivation of theX-chromosome in interspecific hybrid voles

Abstract

SummaryExpression ofX-linked genes for G6PD and GALA in interspecific hybrids betweenMicrotus arvalis, M. subarvalisandM. kirgisorumvoles was studied. Quantitative predominance of the enzyme activities ofM. arvalisover G6PD activity ofM. subarvalisand the GALA activity ofM. kirgisorumin the female hybrids was shown. The definitive patterns of these enzyme activities was found on day 6·5 of embryonic development. Non-random inactivation ofX-chromosomes derived fromM. subarvalisandM. kirgisorumin the interspecific hybrids withM. arvalisis 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 theX-chromosomes derived fromM. subarvalisorM. kirgisorumand the preferential inactivation of these in female hybrids withM. arvalis.