BIOLOGY Volume 3 - A Guide to General Biology - 2004

25. APPLIED GENETICS

25.5. Transgenic Animals

25.5.3. Growth Hormone

Growth Hormone genes were already examined in Sections 25.2.2 and 25.2.3, and the controversy surrounding bovine somatotropin was discussed in Section 25.2.3. Similar issues arose when genes responsible for human growth hormone synthesis were introduced into the animal genome. Transgenic sheep that produced large amounts of human growth hormone grew faster and gained weight more quickly; however, they suffered from more health problems, experienced higher juvenile mortality, and the females were sterile. Transgenic pigs also built up Muscle mass very efficiently, but they exhibited even more side effects than sheep, including Arthritis, gastric ulcers, Heart and Kidney disease. Until Methods for more precise Gene regulation are found, this approach cannot be used for commercial purposes.

More recently, researchers in Canada introduced a gene from another fish (the ocean pout) into the salmon genome, which activates the salmon's own growth hormone gene. Such salmon grew 10 times faster than normal, and their weight reached nearly 30 times the standard level. In 1996, detailed studies of transgenic salmon began at fish farms in Scotland.



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