Analysis of Meiotic Segregation Pattern and Interchromosomal Effects in a Bull Heterozygous for a 3/16 Robertsonian Translocation.

Robertsonian translocations are the most frequent chromosomal rearrangements detected in cattle. Here, we report on the detection of a new Robertsonian translocation between chromosomes BTA3 and BTA16. This rob(3;16) was dicentric, suggesting that its occurrence was recent. FISH analysis of decondensed sperm nuclei revealed a relatively low rate of unbalanced gametes produced by adjacent segregation (5.87%). In addition, and for the first time in bovines, a significant interchromosomal effect (ICE) was detected for 2 different autosomes: BTA17 (global disomy + nullisomy rate of 9%) and BTA20 (1.8%). These results suggest that ICE should be taken into consideration when assessing the putative effect of Robertsonian translocations on reproduction.