Methods and Criticism of Cloning and Genetic Modification

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Biological cloning can be defined as the creation of one or more genetically identical animals by transferring the nucleus of a body cell into an egg from which the nucleus has been removed (S. Ignacimuthu; 2009).  Dolly was the first mammal to be cloned from an adult somatic cell using the process of somatic cell nuclear transfer. She was cloned by Ian Wilmut and colleagues at the Roslin Institute in 1996. Somatic cell nuclear transfer refers to the transfer of the nucleus from an existing organism into an enucleated oocyte. Different techniques are used in somatic cell nuclear transfer. These are The Roslin technique and Honolulu technique.

The Roslin Technique was used to create one of the world’s most famous clones, Dolly the Sheep. The cloning of Dolly was a breakthrough in several ways. It demonstrated that the full genetic complement of somatic cells derived from adult animals could be reactivated well into the chronicle life of the cell (  ).

Researchers took mammary gland cells from an adult Finn Dorset sheep, and grew the cells in tissue culture. Using the tissue culture, they made sure that the cells didn’t have access to specific nutrients so they couldn’t grow and divide. This was achieved by placing the cells in a salt solution and inducing a state of hibernation by starving the cells, providing just enough growth factor to keep the cells alive. The cells stopped dividing and copying DNA and seemed to switch all but the most important genes. It was this treatment that enabled the nucleus-free egg to program the donor nucleus (Morton Jenkins; 2003).   They extracted the nucleus from the somatic cell. This process was repeated many times to get many nuclei from many somatic cells. The nucleus was removed from the cell using a micro-pittete. They then removed the nucleus of an unfertilized egg (oocyte) which had been extracted from a Scottish Blackface ewe. During cloning process many eggs are needed because all the eggs do not survive during the complete process.

Extracted somatic cell nucleus was the inserted into the fertilized egg which is also without nucleus. The introduction of a crucial step needed to synchronize the cell cycles of both the donor and recipient was critical; the donor cell was transferred from 10% fetal calf serum to 0.5% fetal calf serum for five days, causing it to become quiescent. This allowed for enucleation and subsequent implantation of the somatic cell nucleus into an enucleated oocyte of a different organ ( ).   The Egg contained all the traits of genetic material from its donor; the egg became identical to the donor parents.  A small spark of electricity was used for the nucleus to fuse with the cytoplasm of the oocyte. The use of an electricity pulse is to fuse the two cells and to activate embryonic development. This step is thought to mimic the situation normally provided by sperm during sexual reproduction. Once inside the egg; the somatic nucleus is reprogrammed by egg cytoplasmic factors to become a zygote nucleus. The egg is allowed to develop to the blastocyst stage at which a culture of embryonic stem cells can be created from the inner cell mass of the blastocyst. The embryos were then cultured for 5-6 days and those that appeared to be developing normally were implanted into the reproductive chamber of a blackface ewe (the same kind of sheep that gave the oocyte).The whole procedure was repeated 276 times. After 148 days, a normal time for a sheep, Dolly was born.

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b) The experiment was widely criticized by scientists and the general public. Scientists argued that the sheep from which Dolly was cloned was pregnant. It is well known that fetal cells often circulate through the mother`s bloodstream and body , that it was quite possible that one of the fetal cells of that lamb rather than the adult mammary cells of the purported adult donor, was in fact cloned instead. This isn’t all that remarkable, as fetal cells are cloned all the time and even nature does it when identical twins are born.  

Scientists’ criticized the use of an ...

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