Fish Story : Biotech Animals: Part 2

by Food and Drug Administration (FDA)

(Page 2 of 3)

Foods Derived from Transgenic Animals

Taking their lead from the scientists who created new genetically engineered crops that, for example, resist insects without the need for pesticide spraying, researchers involved in the production of food animals began to think about how they could use genetic modifications to improve the production or quality of their products.

Typically, says John Matheson, a senior review scientist in FDA's Center for Veterinary Medicine (CVM), "Researchers start with the protein they want to add and work backwards." It's the protein that the transplanted gene encodes that actually gives the animal a new trait.

The best example so far of the transgenic strategy in food animals, and its success, is the faster-growing salmon. The science behind the so-called supersalmon was discovered by accident 20 years ago when Choy Hew, PhD, then a researcher at Memorial University of Newfoundland in Canada, accidentally froze a tank filled with a particular species of flounder. When the tank was thawed out, the flounder were still alive. Initially, no one knew how they survived. This species, it turns out, has a gene that produces a protein that works like the antifreeze in a car's radiator. This antifreeze protein is found in many types of polar fish that must survive extremely cold conditions.

Researchers isolated and copied the part of the flounder DNA that works like a genetic switch to turn on the production of the antifreeze protein. Normally, this genetic switch is only turned on when the fish is exposed to cold.

Hew and his colleagues then attached the flounder's genetic on-switch to a previously isolated gene from Chinook salmon that produces a growth-stimulating hormone. Using transgenic techniques, they inserted the new combination — the flounder on-switch with the salmon growth hormone gene — into fertilized salmon eggs. In the resulting salmon, the flounder's genetic switch appears to stay turned on, producing a continuous supply of salmon growth hormone that then accelerates the fish's development. While the resulting fish do not seem to reach a mature size that is larger than conventional salmon, they grow much faster.

Breeding transgenic varieties is an effective way to create an animal with a new characteristic, but large mammals-cows, pigs and goats-don't multiply as plentifully or as rapidly as fish. Several research teams have turned to cloning — as in Dolly, the sheep — as a way to expand the herd of transgenic animals. This approach combines two cutting-edge techniques. First, a transgenic animal with the desired characteristics is created. Then, cloning techniques are used to create replicas of the transgenic animal. Using a transgenic approach just makes it easier to get the desired genetic characteristics in the animal, which is then cloned to produce a core breeding herd.

Transgenic Critics

Useful as it may be, animal biotechnology won't go forward without objections. For all the promise that industry sees in the dawning era of genetically engineered animals, others-including animal rights activists, environmentalists, and consumers-see problems.

The concern about genetically engineered foods, says Carol Tucker Foreman, director of the Food Policy Institute at the Consumer Federation of America (CFA) in Washington, D.C., "is in marked contrast to the public acceptance of genetically engineered drugs. When faced with serious illness, most people are willing to take risks to combat a disease." Food is different, she says, since it is so basic, both physically and emotionally. "It's not surprising that consumers are extremely averse to any food-related risk, especially if the risk is perceived as imposed by someone else, beyond individual control and without any countervailing benefit." Consumers, she says, are concerned mostly about such potential health problems as allergic reactions and antibiotic resistance.

But FDA Commissioner Jane E. Henney, MD, points out that foods produced using bioengineering processes are evaluated to make sure they are not more likely to cause allergies. "Under the law and FDA's biotech food policy," she says, "companies must tell consumers on the food label when a product includes a gene from one of the common allergy-causing foods, unless it can show that the protein produced by the added gene does not make the food cause allergies."

But Art Jaeger believes, "It's not just about dangerous foods — it's also a matter of consumer choice." The assistant director for CFA and advocate for mandatory labeling says consumers need to know when a food is genetically altered because many have religious or cultural convictions that would preclude them from selecting foods produced through transgenic technology. Jaeger says that his organization wants tougher regulations and feels that all information on the safety of biotechnology applications should be made publicly available.

And then there are environmental concerns. Purdue University animal scientist Bill Muir and biologist Rick Howard conducted a study funded by USDA on genetically engineered fish, which led them to warn of possible risks from transgenic fish escaping into nature. They worry that transgenic fish escaping from aquaculture facilities into the wild, for example, could damage native populations, even to the point of extinction. But Elliot Entis, president of A/F Protein, Inc., an international biotechnology firm based in Waltham, Mass., feels that environmental concerns can be addressed by producing transgenic fish in closed aquaculture systems (controlled, artificial environments) or by producing all female, sterile fish.

FDA, in cooperation with other federal agencies, will evaluate these proposed environmental safety measures prior to any approval.

About the Author

www.fda.gov
FDA is A United States government body that oversees medical devices, including contact lenses, intraocular lenses, excimer lasers and eyedrops. In the US, these products must be approved by the FDA before they can be marketed.