Κυριακή, 5 Δεκεμβρίου 2010

12 Bizarre Examples of Genetic Engineering.

Glow-in-the-dark cats? It may sound like science fiction, but they’ve been around for years. Cabbages that produce scorpion poison? It’s been done. Oh, and the next time you need a vaccine, the doctor might just give you a banana.

These and many other genetically modified organisms exist today because their DNA has been altered and combined with other DNA to create an entirely new set of genes. You may not realize it, but many of these genetically modified organisms are a part of your daily life — and your daily diet. Today, 45 percent of U.S. corn and 85 percent of U.S. soybeans are genetically engineered, and it’s estimated that 70 to 75 percent of processed foods on grocery store shelves contain genetically engineered ingredients.
Here’s a look at the some of the weirdest genetically engineered plants and animals already in existence — and many that are coming your way soon.
Banana vaccines
People may soon be getting vaccinated for diseases like hepatitis B and cholera by simply taking a bite of banana. Researchers have successfully engineered bananas, potatoes, lettuce, carrots and tobacco to produce vaccines, but they say bananas are the ideal production and delivery vehicle.
When an altered form of a virus is injected into a banana sapling, the virus’ genetic material quickly becomes a permanent part of the plant’s cells. As the plant grows, its cells produce the virus proteins — but not the infectious part of the virus. When people eat a bite of a genetically engineered banana, which is full of virus proteins, their immune systems build up antibodies to fight the disease — just like a traditional vaccine.
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Venomous cabbage
Scientists have recently taken the gene that programs poison in scorpion tails and combined it with cabbage. Why would they want to create venomous cabbage? To limit pesticide use while still preventing caterpillars from damaging cabbage crops. These genetically modified cabbages produce scorpion poison that kills caterpillars when they bite leaves — but the toxin is modified so it isn’t harmful to humans.
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Glow-in-the-dark cats
In 2007, South Korean scientists altered a cat’s DNA to make it glow in the dark and then took that DNA and cloned other cats from it — creating a set of fluffy, fluorescent felines. Here’s how they did it: The researchers took skin cells from Turkish Angora female cats and used a virus to insert genetic instructions for making red fluorescent protein. Then they put the gene-altered nuclei into the eggs for cloning, and the cloned embryos were implanted back into the donor cats — making the cats the surrogate mothers for their own clones.
What’s the point of creating a pet that doubles as a nightlight? Scientists say the ability to engineer animals with fluorescent proteins will enable them to artificially create animals with human genetic diseases.
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Less-flatulent cows
Cows produce significant amounts of methane as a result of their digestion process — it’s produced by a bacterium that’s a byproduct of cows’ high-cellulosic diets that include grass and hay. Methane is a major contributor — second only to carbon dioxide — to the greenhouse effect, so scientists have been working to genetically engineer a cow that produces less methane.
Agriculture research scientists at the University of Alberta have identified the bacterium responsible for producing methane and designed a line of cattle that creates 25 percent less methane than the average cow.
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Medicinal eggs
British scientists have created a breed of genetically modified hens that produce cancer-fighting medicines in their eggs. The animals have had human genes added to their DNA so that human proteins are secreted into the whites of their eggs, along with complex medicinal proteins similar to drugs used to treat skin cancer and other diseases.
What exactly do these disease-fighting eggs contain? The hens lay eggs that have miR24, an antibody with potential for treating malignant melanoma and arthritis, and human interferon b-1a, an antiviral drug that resembles modern treatments for multiple sclerosis.
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Web-spinning goats
Strong, flexible spider silk is one of the most valuable materials in nature, and it could be used to make an array of products — from artificial ligaments to parachute cords — if we could just produce it on a commercial scale. In 2000, Nexia Biotechnologies announced it had the answer: a goat that produced spiders’ web protein in its milk.
Researchers inserted a spiders’ dragline silk gene into the goats’ DNA in such a way that the goats would make the silk protein only in their milk. This “silk milk” could then be used to manufacture a web-like material called Biosteel.
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Super carbon-capturing plants
Humans add about nine gigatons of carbon to the atmosphere annually, and plants and trees absorb about five of those gigatons. The remaining carbon contributes to the greenhouse effect and global warming, but scientists are working to create genetically engineered plants and trees that are optimized for capturing this excess carbon.
Carbon can spend decades housed in the leaves, branches, seeds and flowers of plants; however, carbon allocated to a plant’s roots can spend centuries there. Therefore, researchers hope to create bioenergy crops with large root systems that can capture and store carbon underground. Scientists are currently working to genetically modify perennials like switchgrass and Miscanthus because of their extensive root systems.
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The Enviropig, or “Frankenswine,” as critics call it, is a pig that’s been genetically altered to better digest and process phosphorus. Pig manure is high in phytate, a form of phosphorus, so when farmers use the manure as fertilizer, the chemical enters the watershed and causes algae blooms that deplete oxygen in the water and kill marine life.
So scientists added an E. Coli bacteria and mouse DNA to a pig embryo. This modification decreases a pig’s phosphorous output by as much as 70 percent — making the pig more environmentally friendly.
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Pollution-fighting plants
Scientists at the University of Washington are engineering poplar trees that can clean up contamination sites by absorbing groundwater pollutants through their roots. The plants then break the pollutants down into harmless byproducts that are incorporated into their roots, stems and leaves or released into the air.
In laboratory tests, the transgenic plants are able to remove as much as 91 percent of trichloroethylene — the most common groundwater contaminant at U.S. Superfund sites — out of a liquid solution. Regular poplar plants removed just 3 percent of the contaminant.
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Fast-growing salmon
AquaBounty’s genetically modified salmon grows twice as fast as the conventional variety — the photo shows two same-age salmon with the genetically altered one in the rear. The company says the fish has the same flavor, texture, color and odor as a regular salmon; however, the debate continues over whether the fish is safe to eat.
Genetically engineered Atlantic salmon has an added growth hormone from a Chinook salmon that allows the fish to produce growth hormone year-round. Scientists were able to keep the hormone active by using a gene from an eel-like fish called an ocean pout, which acts as an “on switch” for the hormone.
If the FDA approves the sale of the salmon, it will be the first time the government has allowed modified animals to be marketed for human consumption. According to federal guidelines, the fish would not have to be labeled as genetically modified.
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Flavr Savr tomato
The Flavr Savr tomato was the first commercially grown genetically engineered food to be granted a license for human consumption. By adding an antisense gene, the California-based company Calgene hoped to slow the ripening process of the tomato to prevent softening and rotting, while allowing the tomato to retain its natural flavor and color.
The FDA approved the Flavr Savr in 1994; however, the tomatoes were so delicate that they were difficult to transport, and they were off the market by 1997. On top of production and shipping problems, the tomatoes were also reported to have a very bland taste: “The Flavr Savr tomatoes didn’t taste that good because of the variety from which they were developed. There was very little flavor to save,” said Christ Watkins, a horticulture professor at Cornell University..
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Genetically modified trees
Trees are being genetically altered to grow faster, yield better wood and even detect biological attacks. Proponents of genetically engineered trees say biotechnology can help reverse deforestation while satisfying demand for wood and paper products. For example, Australian eucalyptus trees have been altered to withstand freezing temperatures, and loblolly pines have been created with less lignin, the substance that gives trees their rigidity. In 2003, the Pentagon even awarded Colorado State researchers $500,000 to develop pine trees that change color when exposed to biological or chemical attack.
However, critics argue that not enough is known about designer trees’ effect on their natural surroundings — they could spread their genes to natural trees or increase wildfire risk, among other drawbacks. Still, the USDA in June gave approval for ArborGen, a biotechnology company, to begin field trials for 250,000 trees in seven southern states.
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