| Autor: |
Takagui FH; Laboratory of Animal Cytogenetics; Department of General Biology, CCB, Universidade Estadual de Londrina. Rodovia Celso Garcia Cid, PR 445, km 380, Londrina-Brasil., Dias AL; Laboratory of Animal Cytogenetics; Department of General Biology, CCB, Universidade Estadual de Londrina. Rodovia Celso Garcia Cid, PR 445, km 380, Londrina-Brasil., Birindelli JLO; Museum of Zoology, Department of Animal and Plant Biology, CCB, Universidade Estadual de Londrina. Rodovia Celso Garcia Cid, PR 445, km 380, Londrina-Brasil., Swarça AC; Laboratory of Histology and Genetics; Department of Histology; Center of Biological Sciences (CCB); Universidade Estadual de Londrina (UEL). Londrina-Brasil., da Rosa R; Laboratory of Animal Cytogenetics; Department of General Biology, CCB, Universidade Estadual de Londrina. Rodovia Celso Garcia Cid, PR 445, km 380, Londrina-Brasil., Lui RL; Laboratory of Cytogenetics; Center of Biological Sciences and Health: Universidade do Oeste do Paraná, Campus Cascavel. Cascavel - Brasil., Fenocchio AS; Laboratory of General Cytogenetics; Department of Genetics; Facultad de Ciencias Naturales; Universidad Nacional de Misiones. Posadas- Argentina., Giuliano-Caetano L; Laboratory of Animal Cytogenetics; Department of General Biology, CCB, Universidade Estadual de Londrina. Rodovia Celso Garcia Cid, PR 445, km 380, Londrina-Brasil. |
| Abstrakt: |
The family Doradidae (Siluriformes) is an important group of fishes endemic to freshwater ecosystems in South America. Some cytogenetic studies have been conducted focused on the group; however, there are no reports on the occurrence of B chromosomes for the family. In this paper the chromosomal characteristics of Platydoras armatulus (Valenciennes, 1840), Pterodoras granulosus (Valenciennes, 1821) and Ossancora punctata (Kner, 1855) were investigated through classical cytogenetics approaches. The conventional staining reveals 2n=58 in Platydoras armatulus and Pterodoras granulosus , however with distinct karyotypic formulae, possibly originated by pericentric inversions. In Ossancora punctata a derivate karyotype was described with 2n=66 and predominance of acrocentric chromosomes. The C banding pattern was resolutive in discriminating the three species, being considered an important cytotaxonomic marker. All species showed B chromosomes totally heterochromatic with non-Mendelian segregation during meiosis and low frequencies in mitotic cells. The probably origin of these additional elements was through fragmentations of chromosomes of the standard complement, which occurred recently and independently in these three species. The diploid number observed in Ossancora punctata is an evidence of centric fusions and up to the moment it is the highest diploid number reported for Doradidae. |
