Hic
The tissue was vacuum infiltrated in nuclei isolation buffer supplemented with 2% formaldehyde. Adding glycine and additional vacuum infiltration to stop the crosslinking. Fixed tissue was grounded to powder and re-suspended in nuclei isolation buffer. The purified nuclei were digested with 100units of DpnII and marked by incubating with biotin-14-dATP. Removed biotin-14-dATP from non-ligated DNA ends using T4 DNA polymerase. The ligated DNA was sheared into 300-600 bp fragments, and then was blunt-end repaired and A-tailed, followed by purification through biotin-streptavidin-mediated pull down.