title: GSM9499711: HHst.30, dorsal retina, replicate 1; Gallus gallus; ATAC-seq
library_construction_protocol: Fissure and dorsal tissue were manually dissected from each embryonic eye and were separately collected into cold Ringer's solution. Single cell dissociation of dissected tissues was conducted based on previously described methods (Williams et al., 2021). 50,000 isolated cells were counted using a haemacytometer and were resuspended in PBS. Nuclei extraction, transposition reaction, library preparation were all conducted following the previously described 'omni-ATACseq' method (Corces et al., 2017). Libraries were cleaned using AMPure XP beads (Beckman Coulter, Cat no A63880). Library concentration was quantified using Qubit dsDNA High Sensitivity Assay Kits (Invitrogen, Q32851), while library quality was determined using 4200 Tapestation System (Agilent). 75bp paired-end sequencing of pooled libraries was then conducted using the Nextseq 2000 platform (Illumina), with at least 189 million reads generated per sample.