Análise citogenética comparativa de diferentes populações de Rhamdia quelen (Siluriformes, Heptapteridae)

AUTOR(ES)
DATA DE PUBLICAÇÃO

2007

RESUMO

This study presents cytogenetic findings in 29 specimens of Rhamdia quelen from five different localities: Água dos Patos river, Iepê/SP, Água das Pedras river, Londrina/PR, Taquari river, Jataizinho/PR, Plateau of Bodoquena/MS and a fish culture located in Timbó/SC. All the individuals presented 2n = 58, caryotype formulae of 36m + 16sm + 6st and FN = 116. In 26 individuals was observed 1-2 medium size B chromosome with inter as well as intraindividual variation. C banding showed this chromosome completely heterochromatic in specimens from Água dos Patos, Água das Pedras and Taquari river, partially heterochromatic in the specimens from the fish culture and euchromatic in the individuals of Plateau of Bodoquena. NOR was observed in the terminal region of the short arm in the pair 28 (st) in the specimens from Água dos Patos, Água das Pedras and fish culture, that was coincident with secondary constriction; in the individuals from Taquari river the NOR was in the pair 23(sm), showing heteromorphism between the homologues chromosomes; in the specimens from the Plateau of Bodoquena, in the pair 20 (sm). C banding showed the NOR heterochromatic in all specimens, the other chromosomes of Água dos Patos, Água das Pedras, Taquari river and fish culture presented heterochromatin in terminal region of one or both chromosome arms; in the population from Plateau of Bodoquena, father of this marks, showed 3 heterochromatics marks on pair 2 (m), which was 2 terminals and one pericentromeric, while was more evident in one of the chromosomes homologues. The hybridization in situ with 18S DNAr probe was realized in the individuals from the fish culture, confirming one pair of chromosomes (pair 28) bearing the ribosome cistrons. CMA3 staining showed only the NOR rich in pairs GC and DAPI staining didn t show any marks in all Rhamdia quelen populations. The association of CB+ CMA3 presented the same result of the simple staining with CMA3. CB+DAPI gave good result in three populations: Água dos Patos, Água das Pedras and Bodoquena, where was seen some chromosomes with fluorescent marks, however in the last one, was seen one chromosome more fluorescent than the others, probably the chromosome 2 (m), indicating that in these populations the heterochromatin shows some regions rich in AT. These results reveals some personal characters in the Plateau of Bodoquena/MS population.

ASSUNTO(S)

livestock citogenética animal bagre (peixe) - genética animal catfishes animal genetics cytogenetics

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