library_construction_protocol: RNA was harvested using Trizol reagent. 1 μg total RNA  was used for the construction of sequencing libraries. Polyadenylated RNA was isolated from 1 μg of total RNA using two rounds of purification with Dynabeads™ Oligo(dT)25 magnetic beads (Thermo Fisher, Catalog #61005, USA). The enriched poly(A) RNA was subsequently fragmented into small pieces using  the NEBNext® Magnesium RNA Fragmentation Module (NEB, Catalog #E6150, USA) at 94°C for 5–7 minutes. Fragmented RNA was reverse-transcribed into first-strand cDNA using SuperScript™ II Reverse Transcriptase (Invitrogen, Catalog #1896649, USA). Second-strand cDNA synthesis was performed with E. coli DNA Polymerase I (NEB, Catalog #M0209, USA), RNase H (NEB, Catalog #M0297, USA), and dUTP Solution (Thermo Fisher, Catalog #R0133, USA) to incorporate deoxyuridine triphosphate (dUTP) into the second strand. An A-base was then added to the blunt ends of each strandpreparing them for ligation to the indexed adapters. Each adapter contains a T-base overhana for ligaling the adapter to the A-tailedfragmented DNA. Single- or dual-index adapters were ligated to the fragments, followed by size selection using AMPure XP beads. After treatment of the U-labeled second-strand DNAs with heat-labile UDG enzyme (NEB, Cat. #M0280, USA), the ligated products were amplified by PCR under the following conditions: initial denaturation at 95°C for 3 min; 8 cycles of denaturation at 98°C for 15 s, annealing at 60°C for 15 s, and extension at 72°C for 30 s; with a final extension at 72°C for 5 min. The average insert size of the final cDNA library was 300 ± 50 bp.