title: GSM5213354: Day0_H33K27me3_B2 March 16,2020; Mus musculus; ChIP-Seq
library_construction_protocol: Samples were prepared for ChIP-seq as previously described (Lin-Shiao et al, 2018). Briefly, 2x107 mESC (day 0 pluripotent cells and day 6 embryoid bodies) were fixed in 1% formaldehyde in PBS for 5 minutes, and was quenched using 125 mM glycine incubating for 5 minutes. Two replicates were conducted per ChIP. Chromatin was sonicated in the Covaris AFA Ultrasonicator (Fisher Scientific Sonic Dismembrator Model 100) for 15 minutes at 200 power (with duty set to 5 and cycles set as 200) at 4°C. All ChIPs were performed using 600ug of sonicated lysate and 5 ug of antibody.  Antibodies were conjugated to 30 uL of Protein G Magnetic Beads (Dynabeads, Thermo Fisher Scientific 10-003-D), per ChIP. Eluted samples were reverse crosslinked overnight at 65°C, and DNA was purified after treatment with RNAse A (Thermo Fisher Scientific) and Proteinase K (Thermo Fisher Scientific). Sequencing libraries were prepared using the NEBNext Ultra DNA Library Prep Kit for Illumina (New England Biolabs).