GSM4308649: mouse_roundspermatid_input; Mus musculus; ChIP-Seq
Populations of pachytene spermatocytes and round spermatids were recovered using a StaPut gradient as previously described (Bellve et al, 1993).  All isolated fractions were at least 95% pure.  Cells were washed once in PBS and then split into two aliquots.  One aliquot (for ChIP) was fixed in 1% formaldehyde then quenched with 2.5M glycine, while the second (for RNA) was left unfixed.  Both fixed and unfixed aliquots were snap frozen in liquid nitrogen, then stored at -80C.  ChIP was performed as previously described (Lee et al 2006). ChIP-seq libraries were prepared using a TruSeq ChIP sample prep kit (Illumina) according to the manufacturer's instructions, except that size selection was performed after instead of before PCR amplification.