This week, Dr. Heidi DiFrancesca’s Genetics students are testing foods for the presence of foreign DNA to determine whether they are “all natural” or have been genetically engineered. Genetically-modified foods (GMFs) include those that contain corn or other plant products that have been improved through introduction of genes from other species. Presence of such foreign genes in foodstuffs is detected using the same tools that allow federal agencies to see whether the plant’s genome has been modified genetically - molecular methods for cloning and DNA manipulation.
One frequently-encountered genetically-modified crop is corn, where the delta-endotoxin gene from Bacillus thuringiensis is introduced to the genome to enable the plant’s production of the toxin to kill a variety of insects that can ruin the crop. The toxin is harmless to people and other vertebrates – in fact, it is harmless to all but a small collection of insect pests. We could eat the toxin by the handful without effect, but for those susceptible insects one bite means certain death. You may recall the uproar in recent years over GMO/GMF (genetically-modified organisms/genetically-modified foods) and the European bans that resulted, or the threat to monarch butterfly populations some believed to be posed by fields of genetically-modified plants expressing the toxin. The methods and materials to be used in Dr. D’s class were developed by industry to allow for screening of foods for presence of the delta-endotoxin gene.
Students will take common foodstuffs containing corn – perhaps corn chips, perhaps corn tortillas (this is Texas, after all!) – and extract the DNA contained within. Then, using molecular probes for the delta-endotoxin gene sequence they will look for its presence in the DNA recovered. More likely than not, someone’s corn-based product will have the target sequence because it has been genetically modified to improve yield.
Bottom line is our students are learning valuable skills that are used by industry professionals to address real-world concerns. Not a bad week’s work for McMurry’s biomedical science students!