Worm_embryo_extraction_vSS5. Embryos were resuspended in FA buffer (50 mM HEPES/KOH pH 7.5, 1mM EDTA, 1% Triton X-100, 0.1% sodium deoxycholate; 150 mM NaCl) + protease inhibitors. Sample was dounced 30 times using tight pestle at 4ºC, then sonicated 14 times in ice water bath followed by 1 minute pause at the highest setting. Cell debris was removed by centrifuging at 13,000 rpm for 15 minutes at 4ºC and taking the supernatant. Supernatants were filtered through Millipore Ultrafree-MC 0.45 ?m filter units (cat. UFC30HV0S) at 13,000 rpm, 4°C for 1 minute to remove lipids. Protein concentration was determined, and extracts were aliquoted and stored at -80ºC. For a detailed protocol see http://www.modencode.org/. Worm_chromatin_immunoprecipitation_vSS4. 0.3-3 mg extract + 1% sarkosyl was used for each ChIP with 10% taken as input directly into elution buffer (1% SDS in TE, 250 mM NaCl). Antibody was added to each IP sample and incubated overnight at 4ºC. Immune complexes were incubated (2 hrs at 4ºC) with 50 ?l of IgG dynabeads (Dyna), and washed 5 minutes with 1.5 mL of each of the following solutions: ChIP Buffer, ChIP Buffer + 1 M NaCl, ChIP Buffer + 500 mM NaCl, TEL Buffer (10 mM Tris-HCl pH 8.0, 250 mM LiCl, 1% NP-40, 1% sodium deoxycholate, 1 mM EDTA), and 2X TE (10 mM Tris-HCl pH 8.0, 1 mM EDTA). Samples were eluted twice with 150 ?L elution buffer for 15 minutes at 65ºC. Samples were treated with RNAse for 30 minutes at 37ºC. Samples were treated with proteinase K at 55ºC for 1-2 hrs then transfer to 65ºC overnight to reverse crosslinks. DNA was cleaned up using Zymo kit. For a detailed protocol see http://www.modencode.org/. DNA for Library Prep is incubated with an End Repair Enzyme mix (NEB Klenow, T4 DNA polymerase and T4 PNK) to ensure blunt ends. It is then purified and incubated with Exo(-) Klenow fragment in the presence of dATP to add adenosine at the 3? ends (a single A-overhang for more efficient and directed ligation of the adaptors). After a second purification, the DNA fragments is ligated with single-end ?Homebrew? adaptors which contain an index sequence within (Corbin Jones? lab). After ligation, the samples are purified TWICE using SPRI beads, allowing for a size selection step getting rid of excess adaptors. Samples are then amplified by PCR with single end primers. Depending on the original fragmentation of the DNA, samples can either be purified by SPRI or by separation and purification from an agarose gel.