The Thai Journal of Veterinary Medicine


The significantly high similarity of karyotypes were shown between Bos taurus and B. indicus except for morphology of the Y-chromosome. The B. taurus-Y (BTA-Y) is submetacentric whereas the B. indicus-Y (BIN-Y) is acrocentic. Based on the hybridization of the chromosome painting technique, the difference between Y chromosomes in B. taurus and B. indicus was proposed to be originated from the pericentric inversion between these two species. However, hybridization of SRY to the sub-centromeric end of BIN-Y indicated a double pericentric inversion found between B. taurus and B. indicus. We suggested that BTA-Y and BIN-Y were originated from a common ancestor submetacentric Y chromosome with a short p-arm. The BTA-Y was formed by pericentric inversion of a major segment of q-arm and a centromere of the ancestor chromosome whereas the BIN-Y was generated from the ancestor Y chromosome by pericentric inversion of the complete p-arm together with the centromere. A proposed model of a common ancestor sub-metacentric Y of B. taurus and B. indicus had provided a new insight into the evolution of the Y chromosome in the family of Bovidae.

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