library_construction_protocol: Total RNA was extracted using RNeasy Plus Mini Kit (Life Technologies). rRNA was removed from total RNA samples using the RiBO-Zero ™ Kit. Fragmentation buffer was added to the enriched RNA to break the RNA into small fragments. Then, the fragment RNA was used as template, and 6bp random hexamers were added to reverse transcription to synthesize the first cDNA strand. The second strand of cDNA is synthesized by adding buffer, dNTPs , DNA polymerase I and RNase H. After purification, terminal repair, addition of A, and sequencing joint treatment, the synthesized double-strand cDNA was degraded with USER enzyme and enriched by PCR. Finally, PCR products were purified with AMPure XP Beads to obtain the final chain specific libraries. After the library construction was completed, Qubit 2.0 was used for preliminary quantification and dilution of the library, and Agilent 2100 was used to detect the size of inserted fragments of the library. After the inserted fragments met the expectations, qPCR was used to accurately quantify the effective concentration of the library to ensure the quality of the library.