Classical and molecular cytogenetic analyses of mitotic and meiotic cells were performed on two species of Carollia from the family Phyllostomidae (Chiroptera), which have an XX/XY(1)Y(2) sex determination system. Our results show that the species Carollia perspicillata and Carollia brevicauda have the same Xq-autosome translocation (neo-X). Using multicolor FISH we observed different levels of condensation of the original X and Y chromosomes when compared to the translocated autosomal segment, a likely consequence of the nucleolar organizer region blocking spreading of inactivation to the autosomal region of the neo-X. The use of chromosome painting showed the behavior of the sex chromosome trivalent--here called the 'neo-XY body'--in meiosis. We compared the variation between the condensation of the original X and Y and the autosome-sex chromosome axis and described the pairing between the original X-Y segments (pseudoautosomal region) and the XY(2) homologous segments, suggesting genetic activity of the latter during meiosis.
Copyright 2009 S. Karger AG, Basel.