Presentation on theme: "GMO Investigator Kit Is your food genetically modified?"— Presentation transcript:
GMO Investigator Kit Is your food genetically modified?
Sherri Andrews, Ph.D. Curriculum and Training Specialist Bio-Rad Laboratories Essy Levy, M.Sc. Curriculum and Training Specialist Bio-Rad Laboratories GMO Investigator Kit Instructors
Why teach GMO testing? Inquiry-based Real-world test Environmental Science Plant Physiology Genetics and biotechnology Bioinformatics/Data Mining Standards-based
GMO Investigator Kit Advantages Extract and amplify DNA from different food samples Perform genuine diagnostic procedures Use PCR and electrophoresis to find GMO foods Sufficient materials for 8 student workstations Complete the activity in three 45 minute lab sessions Laboratory extensions: Real-Time PCR
GMO Workshop Time Line Introduction to GM foods DNA extraction of food products Set up PCR reactions Electrophorese PCR products Analysis and interpretation of results
GMO Investigator Procedures Overview
What is a GMO? "genetically modified organism (GMO)" an organism in which the genetic material has been altered in a way that does not occur naturally by mating and/or natural recombination
US Approval for GM food crops Corn Soy Papaya Canola Potato Chicory Rice Squash Sugarbeet Tomatoes Approval does not necessarily mean these crops are distributed Database of GM crops: Which foods contain GM product?
Sources: Fernandez and McBride, : USDA, National Agriculture Statistics Service, Acreage.
Very ReliableReliableLess ReliableVery Difficult / Not Possible Fresh cornVeggie sausagesVeggie burgersOil Fresh papayaTortilla chipsFried corn snacksSalad dressing Corn bread mixFlavored tortilla chips PopcornCereal (eg cornflakes) Corn mealPuffed corn snacksFriesWheat flour Soy flourMeatballs and burgers containing soy protein Potato chips Soy-based protein drinks/powders Which foods yield viable plant DNA?
Why test for GMO’s? Legislation –US: food labeled “GM-Free” <5% GM –EU: food labeled “GM” if >1% GM –Japan: food labeled “GM” if >5% Export What about unlabeled food?
How to test for GMOs ELISA : Test for presence of proteins expressed from genetic modifications Pro: Quick, cheap, low tech Con: Crop specific, protein stability PCR : Test for presence of inserted foreign DNA Pro: ID different GM crops, DNA stability Con: Expensive, timely
How to test for GMOs Test for GMOs by PCR: 1.Grind food 2.Extract DNA from sample 3.Test sample DNA for viable plant DNA 4.Test sample DNA for genetic modifications
Kit Controls Bio-Rad certified non-GMO food –Verify PCR is not contaminated GMO positive control DNA –Verify GMO-negative result is not due to PCR reaction not working properly Primers to universal plant gene (Photosystem II) –Verify viable DNA was extracted
Why amplify a plant gene? To confirm that viable DNA was extracted and that negative GM result isn’t due to a non-viable template. Use highly conserved chloroplast gene from Photosystem II – part of the light reaction of photosynthesis.
Why use CaMV 35S and NOS? CaMV 35S – Sequence for the promoter of 35S transcript of the Cauliflower mosaic virus. Used because it functions in every plant cell NOS- Sequence for nopaline synthase terminator from soil bacterium Agrobacterium tumefacians Used because it evolved to be recognized in most plants
Laboratory Quick Guide
Extract DNA from food
50 μl Volumetric Measurements
Why these steps? Grinding food to release DNA InstaGene chelates divalent ions (e.g. Mg 2+ ) necessary for DNA degrading enzymes (e.g. DNases) Only 50 μl of food transferred otherwise InstaGene is overwhelmed (~ 5 mg of original material) Boiling releases DNA from food into the InstaGene solution Pellet InstaGene and food debris because InstaGene inhibits PCR reaction (Taq needs Mg ++ ) Mg ++ InstaGene
Set up PCR reactions
The PCR Reaction What do you need? What is needed for PCR? Template - the DNA to be amplified Primers - 2 short specific pieces of DNA whose sequence flanks the target sequence Forward Reverse Nucleotides - dATP, dCTP, dGTP, dTTP Magnesium chloride - enzyme cofactor Buffer - maintains pH & contains salt Taq DNA polymerase – thermophillic enzyme from hot springs
Polymerase Chain Reaction PCR Animation
The PCR Reaction How does it work? Heat (94 o C) to denature DNA strands Cool (59 o C) to anneal primers to template Warm (72 o C) to activate Taq polymerase, which extends primers and replicates DNA Repeat 40 cycles
Why have GM crops? Growing human population Loss of farmable land Remediation of soil Enrich nutrient content
Desirable Traits Pest Resistance Herbicide Tolerance Viral Resistance Drought Resistance Increased Nutritional Value Improved Fruit Altered Ripening
Opponents argue Creation of super pests Creation of super weeds Loss of biodiversity Biotechnology companies control agriculture Health concerns
Method for Genetic Modification of Crops 1.Choose desirable trait 2.Clone the gene 3.Engineer the gene 4.Transform gene into plant 5.Backcross GM plant into high yield crops
Choose desirable trait Pest Resistance: Bt crops Bacillus thuringiensis protein is a delta endotoxin kills corn borers HerbicideTolerance: Round Up Ready crops Agrobacterium tumifaciens protein with resistance to Round Up herbicide (glyphosate) Bacillus thuringiensis Delta endotoxin crystal
Clone the gene Ti plasmid ori Bt gene Bacillus thuringiensis Delta endotoxin crystal Ti genes
Engineer the gene STOP Antibiotic resistance Ti plasmid ori Bt gene Ti genes GO
Backcross GM plant into high yield crops GM plant = yyGG High yield plant = YYgg YYgg x yyGGYyGgYyGg YYgg x YyGg YYgG YygG YYgg Yygg YYgG x YYgG YYgG YYgg YYGg YYGG
GMO positive GMO negative 1: non-GMO food with plant primers 2: non-GMO food with GMO primers 3. Test food with plant primers 4: Test food with GMO primers 5: GMO positive template with plant primers 6: GMO positive template with GMO primers 7: PCR MW Ruler Analysis of Results
GMO Investigator Kit Lab Extensions Independent studies Data Mining/Bioinformatics for specific genes –E.g. Design primers to the cry genes in Bt corn Quantitative Real-Time PCR
Trouble shooting False Positives –Contamination-sterile technique; 10% bleach to clean pipette barrels, mortars & pestles, bench tops; barrier tips for all steps. False Negatives –No DNA extracted –Possible food type or possibly primers do not work on that plant species –InstaGene matrix transferred to PCR reactions
GMO Investigator Kit Contents Not Included but required: Thermal cycler Water bath/heat block Electrophoresis Module (agarose, TAE buffer & Fast Blast DNA stain) Electrophoresis equipment & power supply 2-20 ul pipettes & barrier tips Bio-Rad certified Non-GMO food InstaGene Master Mix GMO primers Plant PSII primers GMO & PSII positive control DNA PCR MW Ruler DPTPs, microtubes, PCR tubes, foam floats Manual