Intra-sample heterogeneity of sperm DNA methylation

Genome wide DNA methylation profiling of 2 distinct subpopulations of sperm within a single ejaculate. The Illumina Infinium 450k Human DNA methylation Beadchip was used to obtain DNA methylation profiles across approximately 450,000 CpGs. Samples were provided by 20 normozoospermic individuals. A density gradient centrifugation was performed on each samples to yeild two distict populations for each ejaculate (one from the 90% isolate layer high quality sperm and one from the 35% isolate layer low quality sperm of the column). Bisulphite converted DNA from the 40 samples were hybridised to the Illumina Infinium 450k Human Methylation Beadchip