Worm_embryo_extraction_vSS2. 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 9 times on ice at the following settings: 30 sec; power output 3; 70% duty cycle. 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/. Worm_ChIP-seq_ DNA_Library_Prep_vSS2. ChIP and 10ng of input are blunted (T4 polymerase), an A-overhang is added (Klenow), DNA is ligated (concentrated T4 ligase) to annealed adaptors, amplified by PCR, and size-selected to the 300-400 bp range. Changes: Add AMPure cleanup after ligate adapter step. During size selection, increase run time to 3 hrs and decrease voltage to 80V. Increase size selection to at least 300 bp.