library_construction_protocol: Total RNA was first pretreated to remove some RNA modifications that interfere with small RNA-seq library construction by Agilent DNA 1000 chip kit (Agilent, part # 5067-1504). Diluted libraries were loaded onto reagent cartridge and forwarded to sequencing run on Illumina NextSeq 500 system using NextSeq 500/550 V2 kit (#FC-4042005, Illumina), according to the manufacturer's instructions.