Caracterização citogenética do gênero Eigenmannia (Teleostei:Gymnotiformes) das bacias Amazônicas, do Prata e do rio São Francisco: inferências sobre a diversificação cariotípica e origem e evolução dos cromossomos sexuais

• Autor(a) principal: Jaime, Cristian Andrés Araya [UNESP]
• Data de Publicação: 2015
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: Repositório Institucional da UNESP
• Texto Completo: http://hdl.handle.net/11449/140230; http://www.athena.biblioteca.unesp.br/exlibris/bd/cathedra/10-06-2016/000866048.pdf
• topic: Peixe - Genética; Teleosteos; Citogenetica; Meiose; Genetica molecular; Cromossomos sexuais; Sex chromosomes; Fishes - Genetics

In the present study, six species/cytotypes from de genus Eigenmannia collected at different Brazilian hydrographic basins were analyzed, including E. microstoma, E. limbata and E. virescens, E. aff trilineata, Eigenmannia sp1, and Eigenmannia sp2 using classical (Giemsa conventional staining and C-banding) and molecular cytogenetic techniques (fluorescence in situ hybridization with 5S and 18S rDNA, H3/H4 histone genes and U2 snDNA probes). Besides that, it was studied the meiotic behavior and the differentiation level of multiple sex chromosome system in Eigenmannia sp2 by immunodetection for synaptonemal complex proteins (SYCP3), proteins related to chromatin activity (H3K9me) and associated markers with the bivalent level pairing of the meiotic chromosomes (γH2AX). Finally, the cytogenetics results were analyzed in conjunction with the barcode DNA analysis for a better delineation of species/cytotypes studied. The analyzed species/cytotypes showed diploid number variation, with diploid numbers ranging from 28 chromosomes in Eigenmannia sp1 to 38 chromosomes in E. microstoma, E. limbata and E. virescens. In E. aff trilineata, for the first time, showed a ZZ/Z0 sex chromosome system, where males have karyotypes with 32 chromosomes to 31 chromosomes to females. 5S rDNA and U2 snDNA were located on different chromosomes, with variations on the number of clusters in the different species, while the 18S rDNA was conserved in number of sites per genome and variable in location. The meiotic analysis in the sex chromosomes of Eigenmannia sp2 showed a completely synaptic sexual trivalent X1X2Y formation without unsynaptics presence and inactive chromatin regions throughout its structure. These results suggest that this sex chromosomes system would be a recent rearrangement or simply it is a sex-linked character in this population. All the six species/cytotypes of Eigenmannia analyzed were easily ...