Using the Bovine SNP60k array to discover de novo copy number variations in aging bulls and fibroblasts

We have identified de novo copy number variations (CNVs) generated in ageing bulls. Blood samples from eight bulls were collected and SNP arrayed in a prospective design over 30 months allowing us to differentiate de novo CNVs from constant CNVs that are present throughout the sampling period. Quite remarkably, the total number of CNVs doubled over the 30-month period, as we observed an almost equal number of de novo and constant CNVs (107 vs. 111 or 49% vs. 51%, respectively). Twice as many de novo CNVs emerged during the second half of the sampling schedule as in the first part. It suggests a dynamic generation of de novo CNVs in the bovine genome that becomes more frequent, as the age of the animal progresses. In a second experiment de novo CNVs were detected through in vitro ageing of bovine fibroblasts by sampling passage #5, #15 and #25. De novo CNVs also became more frequent, but the proportion of them was only ~25% of the total number of CNVs (21 vs. 64). Temporal generation of de novo CNVs resulted in increasing genome coverage. Genes and quantitative trait loci overlapping de novo CNVs were further investigated for ageing related functions. One array (24 samples) ran with 3 samples collected over 30 months from 8 bulls to investigate in vivo aging, another array ran 3 samples collected from Passage 5, 15 and 25 from 3 bovine fibroblast cultures.