Lysates were clarified from sonicated nuclei and histone-DNA complexes were isolated with polyclonal αdBigH1 and αH1 antibodies. Finally DNA was purified by standard phenol extraction. 3-5 ng DNA, quantified by Qubit dsDNA HS Assay Kit (Invitrogen) was used for library preparation. Endrepair, adenylation, ligation of adapters and PCR enrichment for 10 cycles was performed using NEBNext Ultra II DNA Library Prep Kit for Illumina (NEB) according to manufacturer's recommendations. Purified libraries were quantified by Qubit dsDNA HS Assay Kit (Invitrogen) and size distribution was evaluated using Bioanalyzer DNA 1000 assay (Agilent).