Genetically Modified Organisms: OMG, GMOs! What's all the fuss over?

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When the term “genetically engineered” is used today, the first thing that probably comes to mind is the modification of food, or the company Monsanto. Or maybe the poison fruit and creepy mutts in The Hunger Games. But what exactly is genetic engineering, what can it be used for, and why do people get so worked up about it?

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The definition of genetic engineering according to the European Commission encompasses anything that artificially alters the genome of an organism.  Genomes are comprised of DNA (or RNA in some viruses) and contain all of the information about an organism’s traits and characteristics passed to its offspring. This is true for plants, animals, bacteria, fungi, viruses, or any other living system.

Selective breeding (or artificial selection) is a form of genetic engineering that has been used for centuries. It’s how we get purebred animals that we use for a specific purpose, like domesticated dogs, dairy cows, and horses. We can select the trait that we desire in a plant or animal and breed them to only display that trait. Charles Darwin used selective breeding to demonstrate his theory of evolution, showing that it produces a change over time.

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How does genetic engineering work?

rDNA technology cuts and pastes together DNA sequences from separate organisms using enzymes. Enzymes are special proteins that help reactions happen faster through a process called catalysis. They have a very specific shape based on the reactions they catalyze, fitting together with the system like a lock and key; in the case of rDNA technology, a type of enzyme called a restriction enzyme precisely fits around the DNA strands to cut the genes with a desired trait from an organism. Restriction enzymes specifically cut DNA strands at an exact location according to their sequence code.

Using another type of enzyme called a ligase, the DNA with the desired trait is pasted (or ligated) into a plasmid - a bacterial DNA molecule that is separate from chromosomal (organized) DNA within a cell that can make copies of itself. The rDNA copies are called recombinant vectors and are put into a host cell, usually a bacteria (like e. coli) or yeast (bakers yeast), to reproduce the vector along with the host cell’s DNA through cell division. The result is a genetically modified organism, or GMO.

The video below does a great job visually describing how this process works.

What can GMOs be used for?

An increasing population in a changing climate has resulted in a growing food shortage and more diversity in disease. These circumstances have motivated the production of GMOs to increase the world’s food production through modified plants and animals and use them to help develop new drugs to treat disease.

The problem of food shortage has resulted in a need for crop production in unusual circumstances like drought, unusual temperatures, and pests. GMOs are widely used in agriculture for a variety of applications including: increasing crop yield, reducing pesticide use, resisting disease and pests, and introducing new vitamins and minerals into food.  

Agriculture currently has the most use for GMOs to improve crop production. An example commonly presented in the media is the soybean gene being altered to tolerate the Roundup weed killer (“Roundup ready” seeds) so that crops can be sprayed to avoid weeds and still produce beans by combining its genes with those of a soil bacterium. Another popular example is corn genes combined with a protein expressing the traits of an insecticide so corn crops are resistant to insects. These examples can increase the amount of food we are able to produce to help meet global demand.

Food can also be enhanced to be more nutritious through genetic engineering. Rice has been successfully modified to retain beta-carotene, which is a precursor to vitamin A, in its husks. GMOs can be used to help undeveloped nations produce food they can grow locally containing more essential nutrients. GMOs have the potential to help rising food problems throughout the world.

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One less talked about, and therefore less controversial application is for pharmaceutical companies. GMOs are being developed to use for drugs and vaccines. Currently, tobacco is being genetically modified to produce a vaccine for Hepatitis B (I doubt the Surgeon General knew “tobacco use” would include a cure for a virus when it was advised against). In addition to producing desired medicines, genetic engineering has been used to study the mutation and progression of diseases to assist in developing cures.

GMOs are being developed for many other areas that are not currently marketed. Microorganisms can be optimized to produce sustainable fuels to help lower the effects of climate change. The medical industry is exploring the modification of foods to deliver drugs and vaccines through ingestion instead of shots.  Medical products made from animals and plants to be used for surgical plastics or transplant organs are also being developed.

So what’s all the fuss over GMOs about?

As with any new technology, there are many unknown potential consequences of changing the natural state of an organism. Genes control most defining features of an organism, so altering them can change more than just the intended trait. Metabolism, environmental response, and growth rate could be affected inadvertently. We don’t know if the apple we genetically engineer might unintentionally grow and ripen at a rate that would half its shelf life.  It is feared that genetically engineering animals might increase cancer rates as a result of cell mutation.

Not only does changing the genome affect the modified organism, but unintentional environmental changes could result. For example, humans might be introduced to new allergens produced by genetically modified plants and animals (some argue that this is already happening). One specific fear is that antibiotic (anti-bacterial) resistant GMOs could transfer their resistance to our intestines, which use bacteria to break down food (hence all the “probiotic” yogurt ads out there).

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There are many other potential risks related to economic factors, religious concerns, and federal and international regulation standards. Food imports and exports are already causing international trade regulations to be put in place due to inconsistent regulations between nations. One particular economic consequence is the patenting of GMO seeds. In the most high profile case, Montsanto patented their “Roundup ready” soybean seed, which can unknowingly be blown into other farmer’s cropland leaving those farmers vulnerable to a lawsuit from Monsanto for infringing on their patent.

The future of GMOs

The potential benefits of GMOs to the world are undeniable. They can help us fight world hunger, develop sustainable products, and treat life-threatening disease. However, the risks are potentially very costly. More research is needed to determine exactly what those risks are and how to minimize them. And that means… more science to blog about! So until next time…

Cheers to your brain!


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Reference:

Phillips, T. (2008) Genetically modified organisms (GMOs): Transgenic crops and recombinant DNA technology. Nature Education 1(1):213