The six applications are: (1) Resistance to Biotic Stresses (2) Resistance to Abiotic Stresses (3) Improvement of Crop Yield and Quality (4) Transgenic Plants with Improved Nutrition(5) Commercial Transgenic Crop Plants and (6) Transgenic Plants as Bioreactors.
Practical applications of transgenics in livestock production include enhanced prolificacy and reproductive performance, increased feed utilization and growth rate, improved carcass composition, improved milk production and/or composition (Figure 1), modification of hair or fiber, and increased disease resistance.
Transgenic means that one or more DNA sequences from another species have been introduced by artificial means. Animals usually are made transgenic by having a small sequence of foreign DNA injected into a fertilized egg or developing embryo.
Examples of GM crops include corn varieties containing a gene for a bacterial pesticide that kills larval pests, and soybeans with an inserted gene that renders them resistant to weed-killers such as Roundup. In 2010, more than 80 percent of U.S. corn, soybeans, cotton, and sugar beets were GM varieties.
GM crops were first introduced in the U.S. in the mid-1990s. Most current GM crops grown in the U.S. are engineered for insect resistance or herbicide tolerance. Corn, soybeans, and cotton are the three largest acreage GM crops. GM crops grown in Colorado include corn, alfalfa, sugar beet, soybeans, and canola.
Genetically modified bacteria are used to produce large amounts of proteins for industrial use. Generally the bacteria are grown to a large volume before the gene encoding the protein is activated. The bacteria are then harvested and the desired protein purified from them.
The pros of GMO crops are that they may contain more nutrients, are grown with fewer pesticides, and are usually cheaper than their non-GMO counterparts. The cons of GMO foods are that they may cause allergic reactions because of their altered DNA and they may increase antibiotic resistance.
- Isolate DNA that codes for the protein you want to express.
- Insert the DNA into a plasmid.
- Insert the plasmid into bacteria.
- Dip the flowering plant into a large amount of bacteria.
- Give bacteria the opportunity to insert the DNA into the plant cells.
- Select for plants that have the insertion.
One specific concern is the possibility for GMOs to negatively affect human health. This could result from differences in nutritional content, allergic response, or undesired side effects such as toxicity, organ damage, or gene transfer.
The possible benefits of genetic engineering include:
- More nutritious food.
- Tastier food.
- Disease- and drought-resistant plants that require fewer environmental resources (such as water and fertilizer)
- Less use of pesticides.
- Increased supply of food with reduced cost and longer shelf life.
- Faster growing plants and animals.
GMOs also reduce the amount of pesticides that need to be sprayed, while simultaneously increasing the amount of crops available to be eaten and sold. Over the last 20 years, GMOs have reduced pesticide applications by 8.2% and helped increase crop yields by 22%.
Transgenic animals are animals (most commonly mice) that have had a foreign gene deliberately inserted into their genome. Such animals are most commonly created by the microinjection of DNA into the pronuclei of a fertilised egg which is subsequently implanted into the oviduct of a pseudopregnant surrogate mother.
In the United States there are 11 commercially available genetically modified crops in the United States: soybeans, corn (field and sweet), canola, cotton, alfalfa, sugar beets, summer squash, papaya, apples and potatoes.
A plasmid is a small, circular, double-stranded DNA molecule that is distinct from a cell's chromosomal DNA. Plasmids naturally exist in bacterial cells, and they also occur in some eukaryotes. Often, the genes carried in plasmids provide bacteria with genetic advantages, such as antibiotic resistance.
