Robertsonian Translocation [56,XX and 57,XY,rob(1;29)] in Captive Thai Gaur (Bos gaurus readei) by Conventional, GTG-Banding, CBG-Banding and Ag-NOR Banding Techniques

Robertsonian translocation, or centric fusion, which is known to be the most common mechanism in karyotype evolution of bovid species, was observed and described in captive Thai gaur (Bos gaurus readei). Blood samples were taken from 2 male and 2 female captive Thai gaur. After the standard whole blood lymphocyte culture in the presence of colchicine, the metaphase spreads were performed on microscopic slides and air-dried. Conventional staining, GTG-banding, CBG-banding and Ag-NOR banding techniques were applied to stain the chromosomes. The number of diploid chromosomes (2n) were 57 in 2 males and 56 in 2 females instead of the normal 2n=58. The fundamental number (NF) was 62 in both the 2 males and 2 females. The autosome consists of 3 submetacentric and 52 telocentric chromosomes in males, and 4 submetacentric and 50 telocentric chromosomes in females. The X chromosome was a large submetacentric chromosome and the Y chromosome was the smallest metacentric chromosome. Eight telocentric chromosomes and 2 submetacentric chromosomes (5 autosome pairs) were identified as satellite chromosomes which showed clearly observable nucleolar organizer regions (NORs). The presence of an extra submetacentric chromosome and the loss of 2 telocentric chromosomes [57,XY,rob(1;29)] were observed in both males. Also, the presence of 2 extra submetacentric chromosomes and the loss of 4 telocentric chromosomes [56,XX,rob(1;29)] were observed in both females. Results from the GTG-banding and CBG-banding techniques analyses confirmed that the 2 autosomes of male (2n=57) and 4 autosomes of female (2n=56) involved in the translocation are the chromosome pairs 1 and 29, which are common in translocation of the bovid species.