The students in my third year lab course are about to test various food products to see if they contain any DNA from genetically modified organisms. They'll be using a variety of PCR primers to detect the Cauliflower mosaic virus 35S promoter and the nopaline synthase terminator sequence from the Ti plasmid of Agrobacterium tumefaciens [see Roundup Ready® Transgenic Plants ].
Every student has to bring in their own food sample to test but I'll be providing a number of "controls" that I picked up in the cafeteria and at the grocery store. Which ones are Frankenfood?
We're using some additional sets of primers as controls. One set detects a chloroplast gene (rbcL). We have two sets of primers for corn-specific genes (invertase and zein) and one set for a soybean specific gene (lectin). An important part of the exercise is figuring out what controls to use and what DNA samples to analyze. Each group of two students can do 24 PCR reactions. It's going to be a challenge for them to figure out which reactions are the most important.
(They were told that corn and soy products are most likely to test positive in the GMO assay.)