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Karyotype stasis in four Atlantic Scombridae fishes: mapping of classic and dual-color FISH markers on chromosomes |
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| Authors: | Rodrigo Xavier Soares Luiz Antonio Carlos Bertollo Gideão Wagner Werneck Félix da Costa Wagner Franco Molina |
| Institution: | 1. Departamento de Genética e Biologia Molecular, Universidade Federal do Rio Grande do Norte, Natal, RN, 59078-970, Brazil 2. Departamento de Genética e Evolu??o, Universidade Federal de S?o Carlos, S?o Carlos, SP, CEP. 67613565-905, Brazil 3. Departamento de Biologia Celular e Genética, Centro de Biociências, Universidade Federal do Rio Grande do Norte, Campus Universitário, Natal, Rio Grande do Norte, CEP 59078-970, Brazil |
| Abstract: | Fish from the family Scombridae exhibit a biogeographical pattern that includes pelagic habits, high swimming ability, and migratory behavior of its species. Although genetic studies aimed at the management and conservation of some of its more intensely exploited species are available, cytogenetic analyses of Scombridae are scarce. In the present study, individuals of four species of this family were obtained in the vicinity of the St. Peter and St. Paul Archipelago in the Mid-Atlantic region. The chromosomes of these four species were analyzed using conventional staining, Ag-NORs, C-banding, CMA3/DAPI fluorochrome staining, and dual-color FISH with 18S and 5S rDNA probes. Acanthocybium solandri and Scomberomorus brasiliensis showed 2n = 48 chromosomes (2st + 46a; FN = 50), while Thunnus albacares and T. obesus, which also had 2n = 48 chromosomes, share another karyotype structure (2m + 2st + 44a; FN = 52). Discrete heterochromatic blocks are present in the centromeric regions of the chromosomes. 18S rDNA/Ag-NORs/CMA3 +/DAPI?sites are located on the short arms of a subtelocentric pair that is apparently homeologous among the four species. The 5S rDNA genes on pair 24 are conserved in all of the species. Cytogenetic patterns showed a high degree of chromosomal conservation between the species. However, Thunnus species displayed greater karyotypic differentiation than A. solandri and S. brasiliensis. Pericentric inversions seem to be the primary mechanism involved in karyotype differentiation in this important fish group. |
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