Definition: Genetic engineering (GE) is one of a group of technologies generally referred to as "biotechnology". Genetic engineering refers to the transfer of individual genes between unrelated species, through the use of "recombinant DNA (rDNA) techniques."
At least in theory, genes from any living organism may be transferred to any other living organism using rDNA techniques. In fact, genes from toads have been integrated into potatoes, bacteria into corn, fish into tomatoes, and human genes have been placed in trees, pigs, rats, and bacteria. The resulting GE organisms (GEOs) are also termed "transgenic".
Goal: The goal of genetic engineering is to:
- incorporate novel traits into familiar organisms (e.g., corn that produces a bacterial toxin with pesticidal properties)
- create new sources of familiar products (rabies vaccine from tomatoes)
- create entirely new products (research animals with human cancer genes).
How is it done? GE is a laboratory procedure in which genetic material is extracted from cells of a "donor" organism, injected into the egg of an animal or (using a variety of other methods) inserted into cells of a plant "host" organism. Transgenic eggs are placed in surrogate mothers and transgenic plant cells are then grown into adult plants. Those with the best commercial properties are then selected.
Several aspects of this technique are important to the issues being raised about genetic engineering:
- Not all host cells will take up the foreign genes. In order to identify which ones have taken up the foreign genes, genetic engineers often attach a gene for resistance to antibiotics to the gene for the desired trait. Then, using antibiotics, they can kill any cells that have not taken up the desired genes, leaving those that are successfully transformed. GEOs containing antibiotic resistance genes, especially GE foods, raise concern about new sources of antibiotic resistance in the environment.
- Insertion of foreign genes into the host cells disrupts the host's normal genetic structure. This can alter host metabolism or function in unexpected ways. Further, the location of the donor genes in the host cannot be controlled and is not known. Thus, the behavior of GEOs may not be entirely predictable.
- Additional "donor genes" are necessary to make the host organism express the desired new trait. Usually "promoter" genes from viruses are added. These "turn on" the gene for the desired trait. It is not clear what other genes these promoters might "turn on," including genes for diseases.
Risks: Because the technology is new, its risks are not fully understood. However, it is apparent that GEOs may potentially:
- act like exotic species if they escape into environments where they have no natural controls
- breed with or pollinate, and thus transfer novel traits to, native plants and animals
- produce residues that would cause environmental or health problems
- have unexpected and undesirable biochemical properties
- be toxic or allergenic
- alter ecosystems in unforeseen ways
- serve as a source of new plant, animal or human diseases
- be used as weapons.
Regulation: There are no laws specific to GEOs; instead, they are regulated under existing statutes by the Food and Drug Administration, the US Department of Agriculture and EPA. FDA regulates GE foods, drugs, cosmetics, and medical devices; USDA regulates GE plants that might become agricultural pests; and EPA regulates GE plants expressing pesticidal properties, as well as microorganisms engineered to produce industrial chemicals.
