title: GSM7782921: Brain, Pathology Aging, sample 6; Homo sapiens; RNA-Seq
library_construction_protocol: Frozen middle frontal neocortex brain tissue was transferred to a pre-chilled dounce homogenizer. Homogenization buffer consisted of 0.25 M sucrose in TKM buffer (50 mM Tris–HCl, pH 7.5, 25 mM KCl, 14 mM MgCl2, and 0.4 U/uL RNAse inhibitor and was added to the dounce homogenizer, at a ratio of 2 mL buffer per 125 mg of tissue. The homogenate was mixed with 2.3 M sucrose + TKM solution to generate a 1.6 M sucrose solution in a chilled ultracentrifuge tube pre-filled with 3 mL cushion buffer (1.8 M sucrose in TKM) and spun at 100,000×g for 45 min at 4 °C in a swinging bucket rotor (Sw-41Ti rotor on an XPN-80 ultracentrifuge). After ultracentrifugation, the myelin layer was removed, the supernatant aspirated and discarded, and the remaining pellet was re-suspended in 1X PBS and RNAsin Plus RNAse inhibitor. Library construction was performed by the Center for Applied Genomics Sequencing Core at the Children's Hospital of Philadelphia in accordance with manufacturer's (10x Genomics) instructions.