Nuclei were isolated from 50 whole larvae per replicate and fixed in 4% formaldehyde for 20 minutes. Chromatin was sonicated to 200-300bp fragments. 2.5% of Drosophila virilis chromatin from 3rd instar larvae was added as a spike-in. 10% of extract was set aside as an input. Pull down was performed with protein A/G magnetic beads preincubated with anti-HP1a PRB-291C (Covance). ThruPlex DNA Seq Kit