Caracterização cromossômica e molecular de bubalinos da traça carabao, do tipo baio e híbridos, mantidos em conservação no Brasil

Abstract

The buffaloes type Baio and race Carabao found in island Marajó-Pará/Brazil are two small populations with very few copies, which makes them extremely susceptible to extinction. According to cytogenetic studies, these animals are divided into two groups of buffalo river that have 2n = 50 and swamp buffaloes with 2n = 48, respectively. The cross between both results in formation of hybrids with 2n = 49 viable and fertile, showing the formation in the offspring of animals 2n =48, 49 or 50. This study evaluated a total of 110 animals (45 of type Baio, 50 and 15 Carabao breed offspring of a female hybrid), all belonging to the Brazilian program of conservation genetic resources. We used techniques of classical cytogenetics and molecular biology, to investigate possible chromosomal changes, hybridization and evolutionary aspects of the buffalo. For the buffaloes type Baio was observed 2n = 50 to 2n = Carabao race 48, in tree was observed 2n = 49 confirming the occurrence of hybridization between animals of the program. For some descendants of the hybrid strain was observed number diploid karyotype and typical breed animals Carabao. The analyzes of microsatellite markers by CSSM06, 8, 42, 66 identified 13, 14, 6 and two Hel9 locus identified three animals, respectively, as hybrids. These results were corroborated with data from genealogical record of the conservation program. Moreover, also characterized the nucleolus organizer regions of Ag-NOR and FISH-18s, being observed a divergence in the number of NORs between type Baio, present on chromosomes 3p, 4p, 6, 21, 23 and 24, and race Carabao 4p, 6, 20, 22 and 23, this being due to the loss of this site on chromosome 4p ancestor of the buffalo river. For the F1 hybrid were observed NORs the 11 sites being expressed and in combination, corresponding NORs of their parents. Genetic analyzes performed in this study were implemented in the conservation program as an auxiliary tool for the selection of animals. Furthermore, these results contribute information on evolutionary aspects between the buffalo and the phenomenon of hybridization.