L57_6mo_Placenta-RRBS
For RRBS, after adding lambda DNA, samples were digested by methylation-insensitive restriction enzyme MspI. Size selection of DNA fragments with insertion lengths ranging from 40bp to 220bp performed by gel cutting. Then the size selected DNA fragments were bisulfite-treated with EZ DNA Methylation Gold Kit (Zymo Research). After the treatment, cytosines without methylation changed to uracyl (after PCR amplification to thymidine), while cytosines with methylation remained unchanged. The final DNA library was obtained by PCR amplification. After the quality control of the library, sequencing was performed on an Illumina HiSeq platform.