Transgenic animals

Transgenic animals are used as experimental models to perform phenotypic tests with genes whose function is unknown. Genetic modification can also produce animals that are susceptible to certain compounds or stresses for testing in biomedical research. Other applications include the production of human hormones like insulin.
In biological research, transgenic fruit flies (Drosophila melanogaster) are model organisms used to study the effects of genetic changes on development. Fruit flies are often preferred over other animals due to their fast generation time, cheap maintenance, and relatively simple genome compared to many vertebrates. Transgenic mice are often used to study cellular and tissue-specific responses to disease.
Transgenesis in fish with promotors driving an over-production of growth hormone (GH) has resulted in dramatic growth enhancement in several species, including salmonids, carps and tilapias. These fish have been created for use in the aquaculture industry to increase meat production and, potentially, reduce fishing pressure on wild stocks. None of these GM fish have yet appeared on the market, mainly due to the concern expressed among the public of the fishes potential negative effect on the ecosystem should they escape from rearing facilities