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Sex-autosome translocations: meiotic behaviour suggests an inactivation block with permanence of autosomal gene activity in Phyllostomid bats

2001; University of Florence; Volume: 54; Issue: 3 Linguagem: Inglês

10.1080/00087114.2001.10589235

2165-5391

Renata Coelho Rodrigues Noronha, Cleusa Yoshiko Nagamachi, Júlio César Pieczarka, Suely Aparecida Marques-Aguiar, Regina Maria de Souza Barros,

Chromosomal and Genetic Variations

Abstract Sex-autosome translocations are found in Chiroptera of the Phyllostomidae, leading to multiple XY1Y2 and composite neo-XY systems of chromosomal sex determination. We compared the behaviour of the sex chromosomes of Glossophaga soricina with a simple XX/XY system, Artibeus lituratus and A. obscurus with a multiple XX/XY1Y2 system, A. cinereus and Uroderma magnirostrum with a neo-XX/XY system. In this study we utilized the conventional meiosis, synaptonemic complex and C banding techniques. All the speciesform a characteristic sex vesicle in pachytene cells; whereas the diplotene cells present chiasmata points along the autosomal bivalents. In the sex chromosomes of the species with a simple system end-to-end pairing was observed for the small region of homology between X and Y, folding of the asynaptic axis of X over itself and differential condensed axes. In species with multiple and composite systems two pairing regions were visualized: the region of end-to-endpairing, as in the simple system and the pairing between the translocated autosome for the X with its homologue. Meiotic data confirm asynchronization and inactivity of the asynaptic axes of the original sex chromosomes in relation to the autosomal bivalents in the three sex chromosome systems and permanence of genic activity of the autosomes translocated to the sex chromosomes in the multiple and composite systems. This genic activity may be due to some mechanismthat blocks the diffusion of inactivation, impeding its progression to the segments of the translocated autosomes. It is probable that this occurs so as to ensure the fertility of these animals.