With many of the new high-throughput there is a need for being able to input several different samples to the same sequencing run. One method is to tag the sequences with a unique identifier during the preparation of the sample for sequencing [Meyer et al., 2007].

Screenshot 1: Tagging the target sequence. From [Meyer et al., 2007].

With this technique, each sequence will have a sample-specific tag - a special sequence of nucleotides before and after the sequence of interest.

The sample-specific tag - also called the barcode - can then be used to distinguish between the different samples when analyzing the sequence data. This post-processing of the sequencing data has been made easy by the multiplexing functionality of the CLC Genomics Workbench.

When separating the sequence list in CLC Genomics Workbench, you will be able to specify the details of the different elements of the tagging:

• Linker: This is a sequence which should just be ignored - it is neither the barcode nor the sequence of interest [Meyer et.al: The Srfl site].
• Barcode: The barcode is the stretch of nucleotides used to group the sequences
• Sequence: This element (the specific tag) defines the sequence of interest. You can define a length interval for how long you expect this sequence to be.

The concept when adding elements is that you add e.g. a linker, a barcode and a sequence in the desired sequential order.

Screenshot 2: Processing the tags