Isolated germ cell nuclei were sonicated in a Misonix S-4000 water bath sonicator, and immunoprecipated overnight using 5 µg of anti-H3K27me3 or anti-H3K36me3 antibody. ChIP-seq library preparation for enriched DNA and the genomic DNA input control for two biological replicates per genotype was performed as described in (Zhong et al. 2010). Libraries were multiplexed as described in Lefrancois et al. (2009) in order to sequence four samples in a single flow cell using the Illumina Genome Analyzer II platform.