Genetically Engineered Animals

Genetic engineering of animals involves manipulating or modifying the genetic code of selected animals to alter their characteristics and to introduce certain desired traits. In genetic engineering, part of the genetic code or DNA is added to, deleted from or substituted with the genes of interest.

The genes of interest can be derived from another animal of the same species, an animal of another species, or even an organism of another kingdom. The beauty - and the controversy - of genetic engineering is that gene splicing can be achieved even between totally unrelated species.

The techniques used to carry out genetic engineering of animals include pro-nuclear micro-injection, embryonic stem-cell manipulation and nuclear transfer. Some of the animals created with these techniques include mice, rats, cows, oxes, sheep, goats, pigs, dogs, cats, and rabbits.

There are various reasons why genetic engineering of animals is carried out. Let's look at some of them:

• For research and testing purposes. Adding or deleting genes from organisms enables scientists to study how genes function, the effects of gene mutations, how genetic diseases occur, and how to treat them.

• To create medically valuable synthetic proteins more economically, and in sufficient quantities. Genetically engineered sheep, for example, can produce milk containing the proteins Factor IX, a human blood clotting factor that can be used to treat haemophilia, and Alpha 1-antitrypsin, which can be used to treat emphysema and cystic fibrosis.

• To create animals that could be possibly used in the future for Xenotransplantation. That is, for providing replacement organs and tissues to human patients. For example, organs like hearts and kidneys can be harvested from genetically modified pigs. As these modified pigs carry a human protein regulating complement, the chances of organ rejection are reduced.

• To create more productive and disease-resistant farm animals. For example, cows that produce more milk, pigs that produce leaner bacon, sheep that produce more wool, and animals born without inherited conditions like hip dysplasia. Scientists at Nexia Biotechnologies have introduced the silk protein gene of a silk-producing spider into a goat's genetic makeup to create transgenic goats capable of producing milk containing the silk protein. Silk fiber can be extracted from this milk and used for various purposes, including making bullet-proof vests and medical sutures.

• To save endangered species. Chinese geneticists are carrying out experiments to clone the panda.

Please see the following articles on genetic engineering in animals -

Genetically Modified Organisms: Different Squeaks From Genetically Altered Mice

Equine Color Genetics. How Horses Get Their Color

Evolution and Aggressive Behavior - Domestication of the Russian Silver Fox

How the Cow Genome could Transform Farming

The Genetic Origins of the California Wolverine

http://www.boyd-group.demon.co.uk/genmod.htm

http://www.srtp.org.uk/geneng2.htm

http://ucanr.org/freepubs/docs/8184.pdf

http://www.organicconsumers.org/Patent/xgenicanimals.cfm

http://jas.fass.org/cgi/content/abstract/74/3/535

http://www.actionbioscience.org/biotech/glenn.html