Figure 1. A strategy for preparing a multiplexed sequencing library.
Lines indicate DNA strands. Grey indicates the target DNA molecules to be sequenced and black indicates adapters. The adapters are ligated to the ends of the target DNA molecules and filled in to make them blunt-ended. Indexing is performed at the last step of library PCR amplification. The indices are depicted as striped segments within the adapters. In the sequencing reaction, they are identified in a separate short sequencing run (Index read) after the initial sequencing of the DNA (Read 1). Adapted from ref. (10).