GBS services are only for OSU internal projects.  Contact Brett Tyler if you have questions about this policy.

Why do a titration?

It is important to determine the ratio of barcoded adapters to use in a GBS experiment.  If the ratio is not correct then much of the data output represents the primer-dimer and data for the intended library is significantly reduced.  This ratio can be different for each organism-restriction enzyme combination.

Determining the ratio is done empirically by running a titration experiment.  The titration experiment uses eight (8) concentrations of adapters with genomic DNA of the species of interest.

Two micrograms (2ug) of high quality genomic DNA (GBS quality) is the total amount needed for the titration experiment.

Eight libraries are prepared using a titration of adapters and assayed on a BioAnalyzer HiSensitivity DNA chip.  The concentration of adapters which gives a good library with the smallest adapter peak is used for a GBS experiment.

Once the ratio of adatpters is determined for a given species and restriction enzyme, that should be used for any GBS experiments with that organism-restriction enzyme combination.

Currently, we are using adapters designed for the ApeKI restriction enzyme.