GM Foods Determination

History of GM Food First release of GM food in US in 1996. GM foods are foods that contain components of GM crops Plants that have been genetically modified by the insertion of foreign genetic material which gives advantages over similar crop plants. Example: Pest resistance, herbicide tolerance, delayed fruit ripening, improved fruit yield, increase nutrient content). Foreign material does not have to be from another plant DNA.

Labeling of GM Foods Currently genetically modified foods do not have to be labeled in US. In addition, foods with less than 5% genetically modified content can be labeled GMO-free. In Europe and Asia, GM food with less than 1% GM content does not require labeling.

Science of GM Foods STEP 1: Identify the protein that has the potential to improve a crop. Example: production of delta-endotoxin that is lethal to European corn borers and silkworms. (gene from Bacillus thuringiensis (Bt) is inserted into corn crop) STEP 2: Isolate (clone) the gene that codes for the protein.

Science of GM Food - continued STEP 3: Engineer genes with correct signaling genes (promoter and terminator) so that the crop plant’s cells will read it correctly and manufacture the protein of interest. Promoter – docking site for RNA polymerase and a signal for where it should start transcribing a gene. Example: 35S promoter of the cauliflower mosaic virus (CaMV 35S) – 203 bp is most commonly used in GM crops. This promoter is chosen because it is already designed by nature to activate transcription in all plant cell types. Terminator – the signal to stop transcription. Example: Terminator of the nopaline synthase (NOS) gene of Agrobacterium tumefaciens – 225 bp One or both of these genetic elements are present in ~85% of all GM crops currently approved around the world.

Step 3: Gene Structure

Science of GM Food - continued STEP 4: Transformation Introduction of engineered gene into the plant cell then new plants are grown from those single cells in a special medium (Plant Tissue Culture).

Step 4: Transformation Three Common Method of Introducing Engineered Gene 1. Agrobacterium tumefacien - this bacterium causes crown gall disease by inserting some of its DNA to its host plant’s genome; this unusual property is exploited to transfer the engineered gene into the plant genome. 2. Electroporation - electric current creates pores in cell membranes and allows the entry of the engineered DNA 3. Gene gun - Physically shooting gold (heavy metal) particles coated with engineered DNA into the plant cells. *Markers are needed to ensure transformation Example: antibiotic resistance and green fluorescent protein.

Step 5: Back-Cross GM with most current high-yield crop strains This takes time since only 50% of the high yield crop’s genome is transferred to the genetically modified crop in each cross.

Testing for GM Food ELISA (enzyme-linked immunosorbent assay) to identify the proteins. Antibody based test where it identifies the specific proteins produced by GM plants. Can be used only in fresh produce due to protein degradation during food processing. Specific to each type of protein PCR to identify the sequence of DNA that has been inserted into the plant DNA. Not specific to the type of protein and can be used for about 85% of the GM products.

Testing for GM Food Protocol Extraction of DNA (GM positive, GM negative, and Test sample) PCR Amplify 35S promoter and photosystem II gene sequences directly from template DNA (DNA from photosystem II chloroplast gene common in most plants – 455 bp). Gel Electrophoresis 3% agarose gel (1x TAE buffer) or 10% polyarylamide gel (10x TBE buffer)

Concerns Regarding GM foods Cons Potential Superweeds – arise through cross pollination of natural weed species with herbicide-resistant crops. Potential Superbugs – no longer susceptible to the toxins in pest resistant crops. Potential allergic reactions Religious Reasons Corporate Monopoly Reduction of Genetic Diversity(?) Disappearance of original genome

Concerns Regarding GM foods Pros Beneficial for the environment – reduction in herbicides and pesticide usage. Example: Bt Corn Beneficial for human health – improvement in nutritional value of food. Example: Vitamin A in golden rice Vaccine in banana Growth of plants in unfarmable lands. Example: Aluminum resistant corn Higher yield of crops