title: GSM7317754: Cortical inhibitory neurons, replicate 2; Mus musculus; ATAC-seq
library_construction_protocol: Posterior cortex (roughly 3 mm by 3 mm) was dissected in ice-cold choline solution (2.1g/L NaHCO3, 2.16 g/L glucose, 0.172 g/L NaH2PO4·H2O, 7.5 mM MgCl2·6H2O, 2.5 mM KCl, 10 mM HEPES, 15.36 g/L choline chloride, 2.3 g/L ascorbic acid, 0.34 g/L pyruvic acid), and transferred to a Dounce containing homogenization buffer (0.25 M sucrose, 25 mM KCl, 5 mM MgCl2, 20 mM Tricine-KOH, pH 7.8, 1 mM DTT, 0.15 mM spermine, 0.5 mM spermidine, protease inhibitors). The tissue was dounced with a tight pestle until it was well homogenized (10-15 strokes). IGEPAL (final 0.15%) was added, followed by 5-10 more strokes. The homogenate was passed through a 40 µm filter. Tween-20 (final 0.1%) and BSA (final 1%) were added to the filtrate. Nuclei were centrifuged at 500g for 5 min at 4º C and resuspended in 0.5 mL Wash Buffer (10 mM Tris-HCl pH 7.4, 10 mM NaCl, 3 mM MgCl2, 1% BSA, 0.1% Tween-20). Nuclei from each sample were sorted by FACS (Sony SH800Z) based on the Sun1-GFP signal into two wells in a cooled 96-well plate coated with Wash Buffer. We followed the manufacturer's protocol for single cell ATAC (10x Genomics CG000168 Rev A). We used one Chromium Controller (10x Genomics) lane per sample for cell barcoding. Libraries were sequenced on a NextSeq 500 DNA sequencer (Illumina).