Overview of the hybrid selection method. Two specific sequencing targets and their respective capture baits are indicated in blue and red. (a) Generation of RNA bait capture probes. 150mer oligos are synthesized on array in batches of 55,000 and cleaved off. They are made double stranded by PCR amplification and tailed with a T7 RNA polymerase promoter, and RNA capture baits are made by transcription in the presence of biotinylated UTP. (b) Solution hybrid selection. RNA baits (from the top line) are mixed with a size selected pond library of fragments modified with sequencing adaptors. Hybridized fragments are then captured to streptavidin beads and eluted by the with-bead protocol for sequencing. See text for details.