title: DR1
design: Beads (Invitrogen, Carlsbad, CA) with oligo (dT) were used to isolate poly (A) mRNA after total RNA was collected. Fragmentation buffer was added for interrupting mRNA to short fragments. Taking these short fragments as templates, random hexamer-primer was used to synthesize the first-strand cDNA. The second-strand cDNA was synthesized using buffer, dNTPs, RNase H and DNA polymerase I. Short fragments were purified with QIAQuick PCR extraction kit (Qiagen, Hilden, Germany) and resolved with EB buffer for end reparation and adding poly (A). After that, the short fragments were connected with sequencing adaptors. For PCR amplification, we selected suitable fragments as templates, based on agarose gel electrophoresis.