title: GSM5542863: 2054_Hypothalamus_S2; Bos indicus; ATAC-seq
library_construction_protocol: Frozen tissue (20mg) was ground in liquid nitrogen using a mortar and pestle.  The pulverized tissue was transferred to a pre-chilled 2ml Dounce homogenizer containing 1ml cold 1 x homogenization buffer and homogenized with the pestle until a uniform suspension was seen (10-20 strokes).  The homogenate was filtered with a 40uM nylon cell strainer (BD Falcon) before layering onto the iodixanol solution.The ratio of nuclei to enzyme concentration was optimized for each sample by performing transposition reactions containing 50 000, 100 000 and 200 000 nuclei with 2.5ul of tagment enzyme in 50ul of transposition mix .The transposed DNA was amplified with custom primers . Amplified libraries were purified using Agencourt AMPure XP beads (Beckman Coulter) and quality controlled using a Bioanalyser High Sensitivity DNA Analysis kit (Agilent).