A GMO (genetically modified organism) is the result of a laboratory process where genes from the DNA of one species are extracted and artificially forced into the genes of an unrelated plant or animal. The foreign genes may come from bacteria, viruses, insects, animals or even humans. Because this involves the transfer of genes, GMOs are also known as “transgenic” organisms.
This process may be called either Genetic Engineering (GE) or Genetic Modification (GM); they are one and the same.
What is a gene?
Every plant and animal is made of cells, each of which has a center called a nucleus. Inside every nucleus there are strings of DNA, half of which is normally inherited from the mother and half from the father. Short sequences of DNA are called genes. These genes operate in complex networks that are finely regulated to enable the processes of living organisms to happen in the right place and at the right time.
How is genetic engineering done?
Because living organisms have natural barriers to protect themselves against the introduction of DNA from a different species, genetic engineers must force the DNA from one organism into another. Their methods include:
- Using viruses or bacteria to "infect" animal or plant cells with the new DNA.
- Coating DNA onto tiny metal pellets, and firing it with a special gun into the cells.
- Injecting the new DNA into fertilized eggs with a very fine needle.
- Using electric shocks to create holes in the membrane covering sperm, and then forcing the new DNA into the sperm through these holes.
The technology of genetic engineering is currently very crude. It is not possible to insert a new gene with any accuracy, and the transfer of new genes can disrupt the finely controlled network of DNA in an organism.
Current understanding of the way in which DNA works is extremely limited, and any change to the DNA of an organism at any point can have side effects that are impossible to predict or control. The new gene could, for example, alter chemical reactions within the cell or disturb cell functions. This could lead to instability, the creation of new toxins or allergens, and changes in nutritional value.
But haven't growers been grafting trees, breeding animals, and hybridizing seeds for years?
Genetic engineering is completely different from traditional breeding and carries unique risks.
In traditional breeding it is possible to mate a pig with another pig to get a new variety, but is not possible to mate a pig with a potato or a mouse. Even when species that may seem to be closely related do succeed in breeding, the offspring are usually infertile—a horse, for example, can mate with a donkey, but the offspring (a mule) is sterile.
With genetic engineering, scientists can breach species barriers set up by nature. For example, they have spliced fish genes into tomatoes. The results are plants (or animals) with traits that would be virtually impossible to obtain with natural processes, such as crossbreeding or grafting.
What combinations have been tried?
It is now possible for plants to be engineered with genes taken from bacteria, viruses, insects, animals or even humans. Scientists have worked on some interesting combinations:
- Spider genes were inserted into goat DNA, in hopes that the goat milk would contain spider web protein for use in bulletproof vests.
- Cow genes turned pigskins into cowhides.
- Jellyfish genes lit up pigs' noses in the dark.
- Artic fish genes gave tomatoes and strawberries tolerance to frost.
- Corn engineered with human genes (Dow)
- Sugarcane engineered with human genes (Hawaii Agriculture Research Center)
- Corn engineered with jellyfish genes (Stanford University)
- Tobacco engineered with lettuce genes (University of Hawaii)
- Rice engineered with human genes (Applied Phytologics)
- Corn engineered with hepatitis virus genes (Prodigene)
- Potatoes that glowed in the dark when they needed watering.
- Human genes were inserted into corn to produce spermicide.
Genetic modification of plants is not the only biotechnology. The study of DNA does hold promise for many potential applications, including medicine. However, the current technology of GM foods is based on obsolete information and theory, and is prone to dangerous side effects. Economic interests have pushed it onto the market too soon.
Moreover, molecular marker technologies - so called Marker Assisted Selection (MAS) used with conventional breeding - show much promise for developing improved crop varieties, without the potentially dangerous side effects of direct genetic modification.
Where are they? In your food! First introduced into the food supply in the mid-1990s, GMOs are now present in the vast majority of processed foods in the US. While they are banned as food ingredients in Europe and elsewhere, the FDA does not even require the labeling of GMOs in food ingredient lists.
Although there have been attempts to increase nutritional benefits or productivity, the two main traits that have been added to date are herbicide tolerance and the ability of the plant to produce its own pesticide. These results have no health benefit, only economic benefit.