design: To construct a non-directional library, mRNAs were purified from total RNAs using poly-T oligo- attached magnetic beads. After fragmentation, the first-strand cDNA was synthesized using random hexamer primers, followed by the second-strand cDNA synthesis with dTTP. A non- directional library was generated after end repair, A-tailing, adapter ligation, size selection, amplification, and purification. The library was checked with Qubit and real-time PCR for quantification, as well as with a bioanalyzer for size distribution detection. Quantified libraries were pooled and sequenced on Illumina platforms.