The nuclear pellet was resuspended into transposition reaction mixture containing Tn5 transposase from Illumina Nextera DNA Sample Prep Kit and incubated at 37 °C for 30 min. Then the transposase-associated DNA was purified using Qiagen MinElute Purification kit. The DNA was amplified for twelve cycles using KAPA Real-Time Library amplification kit (KAPAbiosystems) with Nextera indexing primers as per Buenrostro et al, 2015. The total amplified DNA was purified using AmPureXP beads.