GSM8704765: c0, d4 PGCLC, Rep.4; Mus musculus; OTHER
Genomic DNAs were purified from 500 (c34 oocyte-like cells ≥ 60 μm in diameter) to 15,000 cells (c7 oogonia-like cells, c13 fetal oocyte-like cells) by using Nucleospin Tissue XS (Macherey-Nagel, 740901) and eluted in 10 μl elution buffer.  The DNA concentration was quantitated by using a Qubit dsDNA HS Assay Kit (Thermo Fisher, Q32854) and 20–140 ng of genomic DNAs were mixed with 1 pg of pUC19 DNA and 20 pg of unmethylated lambda DNA for a total volume of 50 μl.  The DNAs were then fragmented by sonication using an E220 focused-sonicator from Covaris (peak incident power: 140W; duty factor: 10%; cycles per burst: 200; and treatment time: 130 ms).  The fragmented DNA samples were purified by two rounds of Axygen beadspurification (0.7×volumes and then 0.9×volumes). All fragments were applied to library construction using a NEBNext Enzymatic Methy-seq Kit (New England Biolabs, E7120) according to the manufacturer's instructions.  Library concentrations and fragment sizes were evaluated with KAPA Library Quantification Kits (Nippon Genetics, KK4828) and a Labchip GX Touch HT nucleic acid analyzer (Perkin Elmer).  The sequencing was performed using an Illumina Novaseq sequencer (Illumina).