Esttrutura cromossômica e caracterização cariotípica no gênero Characidium (Teleostei, Characiformes, Crenuchidae)

• Autor(a) principal: Scacchetti, Priscilla Cardim [UNESP]
• Data de Publicação: 2015
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: Repositório Institucional da UNESP
• Texto Completo: http://hdl.handle.net/11449/139342; http://www.athena.biblioteca.unesp.br/exlibris/bd/cathedra/13-05-2016/000864281.pdf
• topic: Peixe - Pesquisa; Peixe - Genética; Citogenetica; Análise de DNA; Cromossomos sexuais; Sex chromosomes; Fishes

In the present study, eighteen species from the genus Characidium collected at different river basins were analyzed, including C. cf. zebra, C. tenue, C. xavante, C. stigmosum, Characidium sp1, Characidium sp2, Characidium sp3, Characidium sp4, Characidium sp5, Characidium sp6, C. pterostictum, C. vestigipinne, C. rachovii, C. orientale, C. serrano, C. timbuiense, C. vidali e Characidium sp. aff. C. vidali. The analyses involved classical (Giemsa conventional staining and C-banding) and molecular cytogenetic techniques (fluorescent in situ hybridization with ribosomal 5S and 18S, telomeric, microsatellite motifs and U2 snDNA probes, whole chromosome painting using W-specific probe obtained from C. gomesi-CgW). Besides that, DNA sequencing of restriction-associated DNA (RAD) was carried out in males and females of C. gomesi. All species showed diploid chromosome numbers of 2n=50, with karyotypes mainly composed of meta- and submetacentric types, besides the occurrence of supernumerary chromosomes in Characidium sp. aff. C. vidali and one acrocentric pair in C. pterostictum, C. serrano e C. timbuiense. Also, almost all the analyzed species showed a ZZ/ZW sex chromosome system in distinct evolutionary stages, except Characidium cf. zebra, C. tenue, C. xavante e C. stigmosum. The constitutive heterochromatin was located differentially on the W chromosomes and in interstitial and telomeric position on the Z chromosomes, as well as in the B chromosomes of Characidium sp. aff. C. vidali. 5S rDNA was differentially distributed in the different species, with variations on the number of clusters per genome and position in the karyotype, while the 18S rDNA was conserved in number of sites per genome and variable in location. Conversely, the U2 snDNA distribution was conserved in a single homologous chromosome pair in all species, except in Characidium sp. aff. C. vidali and Characidium sp2. Telomeric probes revealed species with several interstitial...