Cells were fixed for 10 minutes at room temperature by the addition of formaldehyde to a final concentration of 1%, after which glycine was added to a concentration of 100 mM. Cells were then washed twice with PBS and collected into 2 ml of lysis buffer (150 mM NaCl, 20 mM Tris pH 8.0, 2 mM EDTA, 1% triton X-100, protease inhibitor [complete EDTA free, Roche, 04 693 132 001], 100 mM PMSF). The lysate was sonicated to an average of 300-500bp fragments The resulting sonicate was centrifuged at 4000×g for 5 minutes, an aliquot of 10% retained for input and the remaining material transferred to a fresh tube. 5-10 ng DNA was subjected to end repair using Klenow DNA polymerase, T4 ligase and T4 polynucleotide kinase (T4 PNK). A 3′ protruding A base was generated using Taq polymerase and NEXTflex adapters were ligated. The DNA was subjected to 4 cycles PCR amplification using Kappa polymerase and purified DNA was loaded on E-gel for size selection (300 bp). The DNA was isolated, further amplified by PCR and used for cluster generation on the HiSeq2000 genome analyzer