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Genetics and Molecular Biology
On-line version ISSN 1678-4685
KAVALCO, Karine Frehner; PAZZA, Rubens; BERTOLLO, Luiz Antonio Carlos and MOREIRA-FILHO, Orlando. Satellite DNA sites in four species of the genus Astyanax (Teleostei, Characiformes). Genet. Mol. Biol. [online]. 2007, vol.30, n.3, pp. 529-535. ISSN 1678-4685. http://dx.doi.org/10.1590/S1415-47572007000400005.
Cytogenetic data about satellite DNA distribution in four Astyanax species (Characidae) from the Paraitinga river, Paraíba do Sul river basin, Brazil, are presented. In order to characterize the constitutive heterochromatin, C-banding, chromomycin A3 and DAPI fluorescence staining, as well as fluorescence in situ hybridization (FISH) with the satellite DNA As-51 probe were performed. A. scabripinnis and A. parahybae presented 2n = 50 and 2n = 48 chromosomes, respectively. The heterochromatin was located in the pericentromeric and terminal regions of many chromosomes, corresponding to GC-positive regions and to the As-51 satellite DNA in terminal regions. A. intermedius and A. giton, both with 2n = 50 chromosomes, showed little heterochromatin, mostly restricted to the terminal and pericentromeric regions of a few chromosomes. No GC-positive regions, neither any correspondence between the scarce heterochromatin of these species and the As-51 satellite DNA was observed. AT-positive blocks were not detected in any of the species studied. Based on these and other available data, the hypothesis that Astyanax represents a polyphyletic group is discussed.
Keywords : Astyanax; fluorescence in situ hybridization (FISH); heterochromatin; karyotypic diversity; satellite DNA.