Justin D. Ellett - Honors in Biology
Determination of Copy Number of DNA Insertion Cassettes in Canola Plants

We are in the midst of a revolution in the engineering of genetically modified foods. With this revolution comes the need to monitor the movement of transgenes through both genetically modified and naturally occurring plant populations. Should transgenes incorporate into the genomes of weedy relatives of transgenic crops and confer a selective advantage, the potential ecological effects could be devastating. The threat of transfer of the transgenes into weedy populations may be influenced by the number of copies of those genes in the host crop genome. Thus, to accurately assess the risk, it was necessary to determine the copy number of the transgenes. The purpose of this project was to determine, through the process of chemiluminescent Southern blotting, the number of Bt and GFP DNA cassettes that were inserted into the host canola genome.

This investigation began with the characterization of plasmids and the quantification of plant genomic DNA. This led to blotting experiments, where we had primarily positive results. We then verified that our probes were, in fact, specific for the Bt and GFP transgenes through experiments to assess cross-reactivity. Finally, we determined the sensitivity of our procedure, which established a minimum detection level of approximately 10 copies of the transgene. After testing three canola lines, we can conclude that the transgenic canola have no more than 10 copies of these genes, a level low enough that ecological risks may be lower than some have hypothesized.