Adult flies were anesthetised by placing them in ice cold glass dishes, heads were removed and brains were dissected removing any cuticle, retina and trachea. Dissected brains were placed in ice cold PBS. Two brains were used for each ATAC-seq reaction, one male and one female. ATAC-seq was performed as previously described in Davie and Jacobs et al 2015 (PLOS Genetics) ATAC-seq