4.4: Test Food Products for GMO Genes
A protein that has been introduced into plants as a genetically modified trait is Bt endotoxin. Bt endotoxin (Bt toxin) is a toxin that is naturally produced by the bacterium, Bacillus thuringiensis . European corn borers are a type of caterpillar that causes billions of dollars of loss for the corn industry every year. If Bt toxin is consumed by European corn borer larvae it causes the corn borers to die. However, the Bt toxin is quite specific and does harm insects in other orders (such as bees and beetles) or humans. Scientists have created genetically modified corn that contains the Bt toxin gene (Cry), thus allowing the corn to produce the toxin protein (Bt corn).The Bt corn expresses the Bt toxin protein (Bt corn) is therefore resistant to the European corn borer larvae, therefore preventing the loss of crops and money.
Another gene that has been introduced into crops to produce a genetically modified trait is the gene that allows plants to be resistant to the herbicide glyphosate. Glyphosate is a widely used broad spectrum herbicide that kills both broadleaf plants and grasses. Glyphosate is commonly sold under the trade name Roundup. Some bacteria naturally express an enzyme, 5-enolpyruvylshikimate 3-phosphate (EPSP) synthase (CP4 EPSP synthase), that allows plants to survive when exposed to glyphosate. This bacterial gene was introduced into plant genomes to allow the plants to express the CP4 EPSP synthase enzyme. Glyphosate will not harm a field of genetically modified crops that express CP4 EPSP synthase, but the glyphosate will effectively kill any weeds in that field.
GMO test strips, also known as lateral flow devices or immunochromatographic strip tests, allows individuals to determine if a GMO trait is expressed in a crop sample. These tests use antibodies that bind specifically to a genetically engineered protein. If the antibody in the test strip binds to the genetically engineered protein, then a color change is observed on the test strip. This color change displays as a line on the test strip and indicates that that sample contains the genetically modified protein. Test strips have been developed to detect the presence of Bt toxin protein or CP4 EPSP synthase protein in crops. Test strips have also been developed that allow one to detect the presence of glyphosate in crops. When glyphosate is present in food crops, this indicates that glyphosate has been applied to the crop and therefore the crop must be genetically modified in order to survive this herbicide treatment. You will test a food sample for the presence of Bt toxin protein, CP4 EPSP synthase protein or glyphosate to determine if the crop is a genetically modified organism.
Materials needed
- GMO lateral flow test strips
- Food samples for testing
Examples of available lateral test strips:
Test strips for glyphosate: https://detoxproject.org/testing/gly...est-home-food/
Test strips for Cry and CP4 EPSP synthase https://www.envirologix.com/catalog/
Test strips for Cry https://seedburo.com/products/3182?v...13982805819447 (~$371/100 strips)
Test Food Sample for GMO Trait using GMO Lateral Flow Test Strip
- Prepare samples according to manufacturer’s instructions
- Test samples using GMO test strips according to manufacturer’s instructions 3. Analyze the results
Questions for Review
- Antibodies in the GMO test strips bind to what molecules in the sample crop?
- How is the DNA of Bt corn different from the DNA of non-engineered corn?