Embryos were washed, dounced, and sheared as in Anderson et al 2019, except that no sarkosyl was added before shearing. Protein A Dynabeads (50 μL) (ThermoFisher Scientific, 10002D) were washed once in 1 mL FA buffer with protease inhibitors (150 mM NaCl, 50 mM HEPES-KOH pH 7.6, 1 mM EDTA, 1% Triton X-100, 0.1% sodium deoxycholate, 5 mM DTT, protease inhibitor cocktail, 1 mM PMSF). Beads were then incubated with 6.6 μg rat polyclonal anti-SDC-3 antibody (rb3779) for 90 min at room temperature in a total volume of 1 mL FA buffer plus protease inhibitors, and the supernatant was removed. Embryo extract containing approximately 2 mg of total protein was then added to the beads and incubated at room temperature for 90 min in a total volume of 1 mL FA buffer plus protease inhibitors. Beads were washed and DNA eluted as in Kruesi et al 2013. We performed end repair, A-tailing, ligation of NEXTflex DNA Barcodes, and amplification as in Kruesi et al 2013.