Meiotic analyses of the sex chromosomes in Carolliinae-Phyllostomidae (Chiroptera): NOR separates the XY₁Y₂ into two independent parts

Abstract

- Meiotic analyses of the sex chromosomes were made in two different species belonging to the subfamily Carollinae (Phyllostomidae, Chiroptera): Rhinophylla pumilio and Carollia perspicillata. These species have different sex chromosome systems. Through banding techniques, chromosomes homologies between Carollia perspicillata and Rhinophylla pumilio were not found, possibly because Carollia species have highly rearranged chromosomes. Probably, Rhinophylla is better associated to Phyllostomini tribe. Sex vesicle pairing behavior at the meiotic prophase was analyzed in both species. R. pumilio had a simple sex chromosome system (XX/XY), the XY pair showed an asynchronic behavior compared to the autosomal bivalents. The sex vesicle showes the X and Y pairing in the pseudoautosomal region. Moreover, a folding of the X-asynaptic axis on itself and condensed differentiated axes were also identified. In C. perspicillata, with a multiple sex chromosome system (XY₁Y₂), the segments Xp-Y₁ and Xq-Y₂ paired independently from each other. Compared to the autosomes, the sex vesicle showed a precocious pairing behavior. In C. perspicillata, a NOR stained with silver was localized in the X rearranged chromosome. Possibly, this region separates the XY₁Y₂ trivalent in two independent parts: one involving the X and Y₂ autosomal with transcriptional activity, and the other corresponding to the original X and Y sex pair.

Key words:

• Carolliinae
• Meiosis
• genic activity
• translocations
• NOR