title: GSM7108264: right cardiac atrium, atrial fibrillation, H3K27ac, 313, vl0260; Homo sapiens; ChIP-Seq
library_construction_protocol: Samples were weighed and crosslinked when taken from -80C storage. Fixation of protein-DNA interactions was achieved through immersion in 1% formaldehyde solution, where tissue samples were minced with a razor into pieces no bigger than 0.5cm3. 2.5M glycine was then added to quench the formaldehyde and tissue was rinsed with PBS. After homogenization of cross-linked tissues in a dounce tissue grinder, dounced suspensions were centrifuged and pellets were resuspended in three serial lysis buffers according to published protocols (SCHMIDT et al., 2009).  Chromatin was fragmented to 200-400bp fragments on a QSONICA-Q500 sonicator fitted with a 4417 (1/16 inch) tip. ChIP experiments were performed with chromatin obtained from 25-50 mg of atrial tissue and antibodies against H3K27ac (Abcam ab479), for the totality of samples, and H3K4me3 (Millipore CMA304) for a subset of these. Illumina sequencing libraries were prepared from ChIP-enriched DNA using ThruPLEX DNA-seq libaray preparation kit with up to 10ng of input DNA and 8-15 PCR cycles. Libraries were purified using the AMPure XP Cleanup beads to enrich for fragments over 200bp and pooled in equimolar concentrations before sequencing on Illumina NovaSeq Instruments.