| Autor: |
Sousa RPC; 1Faculty of Natural Sciences, Institute of Coastal Studies, Federal University of Pará. Bragança PA, Brazil., Furo IO; 2Faculty of Natural Sciences, Institute of Exact and Natural Sciences, Federal University of Pará. Belém PA, Brazil.; 3Tissue Culture Laboratory, Environment Section, Evandro Chagas Institute, Ananindeua PA, Brazil., O'Brien PCM; 4Cambridge Resource Center for Comparative Genomics, Cambridge, United Kingdom., Oliveira-Filho AB; 1Faculty of Natural Sciences, Institute of Coastal Studies, Federal University of Pará. Bragança PA, Brazil., Vallinoto M; 1Faculty of Natural Sciences, Institute of Coastal Studies, Federal University of Pará. Bragança PA, Brazil.; 5Associated Laboratory, Center for Research in Biodiversity and Genetic Resources, Agrarian Campus of Vairão, University of Porto, Vairão, Portugal., de Oliveira EH; 2Faculty of Natural Sciences, Institute of Exact and Natural Sciences, Federal University of Pará. Belém PA, Brazil.; 3Tissue Culture Laboratory, Environment Section, Evandro Chagas Institute, Ananindeua PA, Brazil., Silva-Oliveira GC; 1Faculty of Natural Sciences, Institute of Coastal Studies, Federal University of Pará. Bragança PA, Brazil. |
| Abstrakt: |
The family Centropomidae includes a number of fish species of high commercial value. One of these species, Centropomus undecimalis , is a target of artisanal, industrial, and sports fisheries and has also considerable potential for captive breeding, which has led to its inclusion in several aquaculture programs. While the biology and ecology of C. undecimalis are relatively well documented, few karyological data are available on this species, and they are still scarce for other centropomids. The few chromosomal data available on this family indicate a conserved karyotype 2n = 48, but it is unclear whether the chromosome microstructure is also conserved. In this study, new cytogenetic data are presented on C. undecimalis from the Amazon coastal zone, including C-banding, Ag-NOR, in situ hybridization with repetitive DNA probes (5S and 18S ribosomal genes), and telomeric (TTAGGG)n sequences. The diploid number of the species was 2n = 48, with heterochromatic blocks in the centromeric and pericentromeric regions, as well as distal signals; the nucleolus organizer regions (NORs) were associated with the heterochromatic region. The 18S and 5S recombinant DNA (rDNA) clusters were located in the distal region of chromosome pairs 1 and 11, respectively. The similarities of the karyotype macrostructure found among the centropomid species reinforce their exceptional chromosomal stability. However, the presence of heterochromatic blocks and location of NORs suggest the occurrence of structural rearrangements, which indicates that evolutionary dynamics at the microstructural level in this group may be relatively complex and should be evaluated carefully in any study that targets the production of hybrids for aquaculture. |
