Citogenética molecular e caracterização cromossômica no gênero Eigenmannia (Teleostei, Gymnotiformes, Sternopygidae)
Carregando...
Arquivos
Data
2011-07-29
Autores
Sene, Viviani França [UNESP]
Título da Revista
ISSN da Revista
Título de Volume
Editor
Universidade Estadual Paulista (Unesp)
Resumo
Foram analisadas seis espécies/citótipos de peixes do gênero Eigenmannia, Eigenmannia sp1, Eigenmannia sp2, E. cf. trilineata, Eigenmannia sp e dois citótipos de E. virescens de diferentes bacias hidrográficas brasileiras, com o uso de técnicas citogenéticas básicas (coloração com Giemsa, localização das RONs pela marcação com nitrato de Prata e bandamento C) e moleculares (hibridação fluorescente in situ com sondas de DNAr 18S e 5S, com sondas teloméricas (TTAGGG)n, com sondas para elementos retrotransponíveis Rex 1 e Rex 3 e também por microdissecção, amplificação e hibridação in situ fluorescente com sonda produzida a partir do cromossomo sexual Y de Eigenmannia sp2). As espécies/citótipos analisados apresentaram intensa variação em seus números diploides, de 2n=28 cromossomos em Eigenmannia sp1, 2n=31/32 em Eigenmannia sp2, 2n=34 em E. cf. trilineata, 2n=36 em Eigenmannia sp e 2n=38 em E. virescens, além da ocorrência de sistema sexual XX-XY no citótipo de E. virescens do rio Ribeirão Claro (chamado de E. virescens-XY) e ausência desse sistema no citótipo do rio Mogi-Guaçu (chamado de E. virescens), bem como a ocorrência de sistema múltiplo do tipo X1X1X2X2-X1X2Y em Eigenmannia sp2 do rio Araquá. O DNAr 5S está organizado em duas classes distintas e foi localizado em diferentes cromossomos entre estas espécies/citótipos, mas sempre em posição terminal dos cromossomos, com exceção apenas do par cromossômico 7 de Eigenmannia sp1, que possui DNAr 5S em posição intersticial. Ainda, sequências de DNAr 5S foram localizadas no par sexual XY do citótipo de E. virescens-XY, evidenciando uma nova característica dos cromossomos sexuais deste grupo. As RONs, identificadas pelo tratamento com nitrato de Prata e pela sonda de DNAr 18S, foram sempre localizadas em compartimentos cromossômicos distintos do DNAr 5S e, apesar de serem localizadas...
Conventional (Giemsa, Ag-NOR, C-banding) and molecular (Fluorescent in situ hybridization with 18S and 5S rDNA probes, telomeric repeats (TTAGGG)n, Rex1 and Rex3 retrotransposable elements and microdissection, amplification and fluorescent in situ hybridization with probes produced from the Y sex chromosome of Eigenmannia sp2.) cytogenetic studies were carried out in six fish species/cytotypes of the genus Eigenmannia from different Brazilian hydrographic basins. The analyzed species/cytotypes presented an intense variation in diploid number, ranging from 2n=28 chromosomes in Eigenmannia sp1, 2n=31/32 in Eigenmannia sp2, 2n=34 in Eigenmannia cf. trilineata, 2n=36 in Eigenmannia sp to 2n=38 in E. virescens, besides the occurrence of a sex chromosome system XX-XY in the cytotypes of E. virescens from Ribeirão Claro river (named as E. virescens-XY) and absence of this sex chromosome system in the cytotypes of Mogi-Guaçu river (named E. virescens), as well as the occurrence of a multiple sex chromosome system X1X1X2X2-X1X2Y in Eigenmannia sp2 from Araquá river. The 5S rDNA is organized in two distinct classes and was located in different chromosomes between these species/cytotypes; on the other hand, the location in the terminal position of chromosomes was a conserved feature, with exception of chromosome pair 7 in Eigenmannia sp1, which had 5S rDNA sites in an interstitial position. Yet, 5S rDNA signals were detected on the XY sex chromosome of E. virescens-XY, showing some new characteristics of sex chromosomes in this group. The NORs, identified by silver nitrate staining and 18S rDNA probes, were always located in distinct chromosome compartments of 5S rDNA and besides located in different chromosomes in all analyzed samples, they remained conserved through the karyotypic differentiation process in this group. The analysis of constitutive heterochromatin... (Complete abstract click electronic access below)
Conventional (Giemsa, Ag-NOR, C-banding) and molecular (Fluorescent in situ hybridization with 18S and 5S rDNA probes, telomeric repeats (TTAGGG)n, Rex1 and Rex3 retrotransposable elements and microdissection, amplification and fluorescent in situ hybridization with probes produced from the Y sex chromosome of Eigenmannia sp2.) cytogenetic studies were carried out in six fish species/cytotypes of the genus Eigenmannia from different Brazilian hydrographic basins. The analyzed species/cytotypes presented an intense variation in diploid number, ranging from 2n=28 chromosomes in Eigenmannia sp1, 2n=31/32 in Eigenmannia sp2, 2n=34 in Eigenmannia cf. trilineata, 2n=36 in Eigenmannia sp to 2n=38 in E. virescens, besides the occurrence of a sex chromosome system XX-XY in the cytotypes of E. virescens from Ribeirão Claro river (named as E. virescens-XY) and absence of this sex chromosome system in the cytotypes of Mogi-Guaçu river (named E. virescens), as well as the occurrence of a multiple sex chromosome system X1X1X2X2-X1X2Y in Eigenmannia sp2 from Araquá river. The 5S rDNA is organized in two distinct classes and was located in different chromosomes between these species/cytotypes; on the other hand, the location in the terminal position of chromosomes was a conserved feature, with exception of chromosome pair 7 in Eigenmannia sp1, which had 5S rDNA sites in an interstitial position. Yet, 5S rDNA signals were detected on the XY sex chromosome of E. virescens-XY, showing some new characteristics of sex chromosomes in this group. The NORs, identified by silver nitrate staining and 18S rDNA probes, were always located in distinct chromosome compartments of 5S rDNA and besides located in different chromosomes in all analyzed samples, they remained conserved through the karyotypic differentiation process in this group. The analysis of constitutive heterochromatin... (Complete abstract click electronic access below)
Descrição
Palavras-chave
Peixe - Genetica, Fish - Genetics
Como citar
SENE, Viviani França. Citogenética molecular e caracterização cromossômica no gênero Eigenmannia (Teleostei, Gymnotiformes, Sternopygidae). 2011. 52 f. Dissertação (mestrado) - Universidade Estadual Paulista, Instituto de Biociências de Botucatu, 2011.