Dissected ovaries were fixed in 1% formaldehyde, lysed and sonicated. Part of the lysate was kept for the input DNA, the rest was incubated with pre-immune serum or with the anti-dLsd1 antibody. Antibody complexes were recovered with a mixture of protein A- and G-Sepharose. The DNA was recovered by phenol-chloroform extraction and ethanol precipitation. For the library preparation, ChIP DNA (10 ng) was blunt-ended and phosphorylated, and a single 'A' nucleotide was added to the 3' ends of the fragments in preparation for ligation to an adapter that has a single-base 'T' overhang. The ligation products was purified and size-selected by agencourt AMPure XP beads. Purified DNA was PCR-amplified to enrich for fragments that have adapters on both ends.