library_construction_protocol: Tatol RNA was extracted by Magzol Reagent (Magen, China) Briefly, RNAs were ligated with 3' RNA adapter, and followed by 5' adapter ligation. Subsequently, the adapter-ligated RNAs were subjected to RT-PCR and amplified with a low-cycle. Then the PCR products were size selected by PAGE gel according to instructions of NEBNext® Ultra™ RNA Library Prep Kit for Illumina (Illumina, USA)