Ian Wilmut and Cloning :: Genetic Engineering Essays

Ian Wilmut and Cloning Before Dolly the cloned sheep made news headlines, the same researchers had only the year before raised seven other sheep from oocytes whose nuclei had been replaced with nuclei from either fetal or embryonic tissue.1 This created a minor stir as this is the "first report to [their] knowledge, of live mammalian offspring following nuclear transfer from an established cell line."1 The implications of this is that they have provided techniques to analyze and modify gene functions in sheep (By providing clones of the same sheep).1 The key to their success is the "serum starvation" that the donor cell undergoes, to force the donor cell into a 'quiescent' state, so that it is not replicating its DNA or dividing. This possibly makes the nucleus more susceptible to re-programming by the recipient egg cell. The researchers built on this knowledge, and carried out a nuclear transfer from cells from the mammary gland of a 6-year old ewe in the last trimester of pregnancy. (instead of fetal or embryonic stem cells). After 277 nuclear transfers, Dolly was born.2 Dolly shows morphological characteristics belonging to the breed (Finn Dorset)that donated the nucleus instead of the oocyte donor or the surrogate mother(Scottish Blackface). Thus erasing any possibility of the birth due to the mating of the surrogate mother with another sheep. In 1975 Gurdon, Laskey & Reeves showed that nuclei transfer from keratinised skin cells of adult frogs supported growth to the tadpole stage 3. Wilmut's experiment took one step further and managed for the organism(Dolly) to grow to adulthood, thereby confirming that adult cells do in fact contain workable versions of all the genes necessary to produce an entire organism. Previously there was widespread belief that cells from adult mammals cannot be persuaded to regenerate a whole organism. Now that Wilmut has proven once and for all that this is otherwise, many cloning experiments that were once fantasy could now be accomplished. For example, an organism of interest can be cloned from any living cells from it if it no longer can reproduce normally (perhaps due to defects in gametes formation) or if only cultured cells of the organism of interest remains (it has already died but complete cell death has not occurred). However, it will take some time before Wilmut's technique is used as an important aid in all manner of biological and biomedical investigations. As forementioned, having to do 277 nuclear transfer just to obtain one living sheep is impractical for most experiments.