Sheep have provided so much for us through the last number of millenia, and their domestication has undoubtedly changed the course of our development as a species. And we, in turn, have changed them...
...but never so much or so quickly as we have over the past three decades. In 1990, Tracy, the transgenic ewe, was born. Tracy was a genetically modified organism, created to produce α1-antitrypsin. She was created by a team lead by British developmental biologist Ian Wilmut at Scotland's Roslin Institute, and was the first transgenic farm mammal in existence.
α1-antitrypsin was being investigated at the time for its potential ability to treat cystic fibrosis as well as some types of emphysema. The use of milk as a treatment was abandoned in the late 1990s, as it was noted that patients developed breathing difficulties as a result.
Wilmut would go on to be responsible for producing Dolly. Dolly, a Finn Dorset sheep, was the first mammal to be cloned from an adult somatic (non-undifferentiated) cell.
Half of the protein of Tracy's milk was comprised of Alpha 1-antitrypsin, a much higher level than in non-genetically modified sheep. Tracy also passed this production trait onto her granddaughters. To this point, bits of DNA would be inserted into the pronuclei of already-fertilized eggs, adding the genes coded for in that DNA. However, the genes are inserted at random and are not always expressed and not always passed along, so Tracy was an enormous success.
From the first tamed mouflon, to Tracy, to Dolly, I am sure we are far from done finding out how sheep will forever change us as a species.
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