Embryos from a 0-4 hour collection were crosslinked in formaldehyde for 15 minutes prior to quenching with glycine and 3 1x PBS washes. Embryos were hand sorted under a dissecting scope in order to collect NC14 stage only. Collected embryos were frozen at -80° until sufficient numbers were collected. To perform ChIP, collected embryos were thawed and homogenized prior to sonication in RIPA buffer. Sheared chromatin was subjected to overnight immunoprecipitation with an anti-GFP antibody and immunocomplexes were precipitated with protein-G dynambeads. Pellets were washed extensively prior to elution and crosslink reversal. ChIP samples were subjected to library preparation using the NEB Next Library Mastermix Kit following the manufacturer's instructions.