Poly-T capture beads were used to isolate mRNA from 10 ug of total RNA. First strand cDNA was generated using random hexamer-primed reverse transcription, and subsequently used to generate second strand cDNA using RNase H and DNA polymerase. Sequencing adapters were ligated using the Illumina Genomic DNA sample prep kit. Fragments ∼200 bp long were isolated by gel electrophoresis, amplified by 16 cycles of PCR, and sequenced on the Illumina Genome Analyzer, as described40 .