Strategy to implement PDD with the split-adapter library preparation method. Fragmented RNA is 3′-polyadenylated and reverse transcribed using a primer with both 5′ (green) and 3′ (red) adapters. Between them (‘X’) is a block for DNA polymerases (here, a C9 abasic spacer). Also present is a 5′-phosphate (P) for subsequent self-ligation. After reverse transcription, RNA template is eliminated and cDNA (blue) circularized and subjected to PDD treatment, whereby it is hybridized to DNA oligonucleotide probes (purple arrow) and any dsDNA formed is cut with DSN, rendering the targets incapable of amplification.