design: Total RNA was extracted from ovarian tissues of S. japonica using TRIzol reagent following the manufacturers instructions. The RNA quality and integrity were assessed using NanoDrop 2000, Qubit 2.0, and Agilent 2100 Bioanalyzer or LabChip GX systems. mRNA was enriched using Oligo(dT) magnetic beads, followed by fragmentation with Fragmentation Buffer. First-strand cDNA was synthesized using random hexamer primers, and second-strand cDNA was subsequently generated with DNA polymerase I and RNase H. Double-stranded cDNA was purified with AMPure XP beads, end-repaired, A-tailed, and ligated to sequencing adapters. Size selection was performed using AMPure XP beads, and the libraries were finally enriched by PCR. Library quality and concentration were evaluated using Qubit, fragment analysis, and qPCR prior to sequencing. Sequencing was performed on the Sentosa SQ301 platform (ELEMENT) with paired-end 150 bp reads (PE155).