2.1 Sampling, DNA extraction, and RNA extraction
Wild adult female C. japonica (approximately 210 g) individuals were collected in December 2019 from Zhoushan. The animal study and procedure were approved by the Animal Ethics Committee of Yantai University. Fresh gill, muscle, heart, and intestinal tissues were collected using sterilized dissection scissor and scalpel and then snap-frozen in liquid nitrogen. High-quality genomic DNA was extracted from the muscle tissues of C. japonica using the Blood & Cell Culture DNA Mini Kit (QIAGEN, GER), and high-quality RNA was extracted from C. japonica tissues using the TRIzol Reagent Kit (Invitrogen, USA). The integrity, purity, and concentration of the genomic DNA were assessed using 1% agarose gel electrophoresis, NanoDrop 2000 analyzer (Thermo Fisher Scientific, USA), and Qubit 3.0 analyzer (Thermo Fisher Scientific, USA). RNA integrity and concentration were measured using the Agilent Bioanalyzer 2100 System (Agilent Technologies, USA) and NanoDrop 2000 analyzer (Thermo Fisher Scientific, USA).