Identification of the homologue of the bovine Rob (1:29) in a captive gaur (Bos gaurus)

Robertsonian translocations have been well documented in domestic cattle, with the most commonly occurring fusion involving chromosomes 1 and 29. The widespread nature of this translocation is indicative of its ancient origin. The gaur (Bos gaurus) is one of many wild cattle species currently listed as vulnerable or endangered. Due to the small founder stock and 50 years of restricted breeding, the captive herd is showing signs of inbreeding and reduced fertility. Recent cytogenetic analysis of a female gaur at Toronto Zoo found that the individual contained 2n=57 chromosomes instead of the normal 2n=58, with an extra submetacentric and the loss of two acrocentric chromosomes being observed. This study was undertaken to identify the translocation in this individual and to examine the karyotype of immediate family members. Chromosome analysis of fibroblast cell cultures was carried out using GTG-banding, C-banding and FISH (bovine 1 and 29 paints) techniques to characterize the translocation. Results from the GTG-banding and FISH analyses confirm that the two autosomes involved in the translocation are the bovine homologues 1 and 29. A monocentric centromere was observed by C-banding. Chromosome abnormalities have not been detected in other gaur tested to date. This study demonstrates the importance of cytogenetic analysis for the establishment of screening protocols for the assessment of reproductive potential in this and other exotic bovinae.