WGBS of shrimp
genomic DNAs were fragmented into 100-300bp by Sonication (Covaris,Massachusetts,USA) and then purified by MiniElute PCR Purification Kit (QIAGEN,MD,USA). End repair was performed on the fragmented DNAs and a single A nucleotide was added to the 3 end of the blunt fragment. Then, the genomic fragments were ligated to methylated sequencing adapters. The fragments with adapters were bisulfite converted using the Methylation-Gold kit (ZYMO,CA,USA), and unmethylated cytosine was converted to uracil during the sodium bisulfite treatment. Finally, the converted DNA fragments were amplified by PCR and sequenced using the Illumina HiSeqTM 2500 platform of Gene Denovo Biotechnology Co. (Guangzhou, China).