Estudos citogenéticos no genêro Characidium (Teleostei, Characiformes, Chrenuchidae), com análise estrutural e molecular do sistema ZZ-ZW de cromossomos sexuais
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2010-02-19
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Alves, Jose Carlos Pansonato [UNESP]
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Universidade Estadual Paulista (Unesp)
Resumo
Foram analisadas onze espécies de peixes do gênero Characidium, Characidium cf. zebra, Characidium cf. gomesi, Characidium lauroi, Characidium oiticicai, Characidium lanei, Characidium pterostictum, Characidium schubarti, Characidium alipioi, Characidium sp1, Characidium sp2 e Characidium sp3 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 (marcação por fluorocromos base-específicos, hibridação in situ fluorescente com sondas de DNAr 18S e 5S, com sondas teloméricas (TTAGGG)n e com sondas para histona H1 e também microdissecção, amplificação e hibridação in situ fluorescente com sondas produzidas a partir do cromossomo sexual W e dos cromossomos B). Todas as espécies apresentaram número diplóide de 2n=50 cromossomos, com predominância dos cromossomos dos tipos meta e submetacêntricos, além da ocorrência de cromossomos supranumerários em C. pterostictum, C. oiticicai, C. cf. gomesi e Characidium sp3. Foi observada também a ocorrência de um sistema ZZ-ZW de cromossomos sexuais representado pelo par heteromórfico número 2 em todas as espécies, com exceção apenas de Characidium cf. zebra, que não apresentou cromossomos sexuais diferenciados. O DNAr 5S foi localizado em diferentes cromossomos entre estas espécies, mas sempre em posição intersticial dos cromossomos, reforçando a idéia de que esta localização cromossômica poderia representar alguma vantagem relacionada à organização destes genes no genoma. As RONs, identificadas pela prata, pela CMA3 e pela sonda de DNAr 18S, foram sempre localizadas em compartimentos cromossômicos distintos do DNAr 5S e estão diretamente relacionadas ao processo de diferenciação dos cromossomos Z e W,...
Eleven species of fish of the genus Characidium comprised by Characidium cf. zebra, Characidium cf. gomesi, Characidium lauroi, Characidium oiticicai, Characidium lanei, Characidium pterostictum, Characidium schubarti, Characidium alipioi, Characidium sp1, Characidium sp2, and Characidium sp3 from different Brazilian hydrographic basins were analyzed using basic cytogenetic (coloration with Giemsa, localization of NORs for silver nitrate marking and C-banding) and molecular techniques (for base-specific fluorochrome markings, fluorescent in situ hybridization with 18S and 5S rDNA probes, telomere probes (TTAGGG)n, and H1 histone, as well as microdissection, amplification and in situ fluorescent hybridization using probes prepared from both sex W and B chromosome). All the species presented a diploid number of 2n=50 chromosomes, with a predominance of the meta- and submetacentric types, besides the occurrence of supranumerary chromosomes in C. pterostictum, C. oiticicai, C. cf. gomesi, and Characidium sp3. The occurrence of a ZZ-ZW sex chromosome system represented by the heteromorphic pair number 2 in all species was observed, with the exception of Characidium cf. zebra, which did not presented differentiated sex chromosomes. The 5S rDNA marks were observed in different chromosomes among these species, but always located in an interstitial position, strengthening the idea that this chromosome location might represent some advantage related to the organization of these genes in the genome. NORs identified using Silver and CMA3, staining and 18S rDNA probe have always been located in distinct chromosome compartments when compared to 5S rDNA, showed to be directly related to the Z and W chromosome differentiation process, and is considered to play an important role in their evolution, considering that they could... (Complete abstract click electronic access below)
Eleven species of fish of the genus Characidium comprised by Characidium cf. zebra, Characidium cf. gomesi, Characidium lauroi, Characidium oiticicai, Characidium lanei, Characidium pterostictum, Characidium schubarti, Characidium alipioi, Characidium sp1, Characidium sp2, and Characidium sp3 from different Brazilian hydrographic basins were analyzed using basic cytogenetic (coloration with Giemsa, localization of NORs for silver nitrate marking and C-banding) and molecular techniques (for base-specific fluorochrome markings, fluorescent in situ hybridization with 18S and 5S rDNA probes, telomere probes (TTAGGG)n, and H1 histone, as well as microdissection, amplification and in situ fluorescent hybridization using probes prepared from both sex W and B chromosome). All the species presented a diploid number of 2n=50 chromosomes, with a predominance of the meta- and submetacentric types, besides the occurrence of supranumerary chromosomes in C. pterostictum, C. oiticicai, C. cf. gomesi, and Characidium sp3. The occurrence of a ZZ-ZW sex chromosome system represented by the heteromorphic pair number 2 in all species was observed, with the exception of Characidium cf. zebra, which did not presented differentiated sex chromosomes. The 5S rDNA marks were observed in different chromosomes among these species, but always located in an interstitial position, strengthening the idea that this chromosome location might represent some advantage related to the organization of these genes in the genome. NORs identified using Silver and CMA3, staining and 18S rDNA probe have always been located in distinct chromosome compartments when compared to 5S rDNA, showed to be directly related to the Z and W chromosome differentiation process, and is considered to play an important role in their evolution, considering that they could... (Complete abstract click electronic access below)
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Palavras-chave
Peixe - Genetica, Citogenética animal, Cromossomos sexuais, Characidium, Cytogenetic, Brazilian hydrographic basins
Como citar
ALVES, Jose Carlos Pansonato. Estudos citogenéticos no genêro Characidium (Teleostei, Characiformes, Chrenuchidae), com análise estrutural e molecular do sistema ZZ-ZW de cromossomos sexuais. 2010. 212 f. Tese (doutorado) - Universidade Estadual Paulista, Instituto de Biociências de Botucatu, 2010.