Total RNA was isolated from dorsal skin tissues using Trizol reagent following manufacturer's instructions. RNA samples were treated with RNase-free DNase I to eliminate genomic DNA contamination. RNA integrity and concentration were assessed using Qubit RNA Assay Kit on a Qubit 2.0 Fluorometer. Stranded mRNA sequencing libraries were constructed using Hieff NGS MaxUp Dual-mode mRNA Library Prep Kit for Illumina (YEASEN, 12301ES96). PCR products were purified with AMPure XP beads and library quality was verified on Agilent Bioanalyzer 2100.