The cloning of Dolly has been the most important event in cloning history. Not only did it spark public interest in the subject, but it also proved that the cloning of adult animals could be accomplished. Previously, it was not known if an adult nucleus was still able to produce a completely new animal. Genetic damage and the simple deactivation of genes in cells were both considered possibly irreversible. "Three years ago we didn't think it could be done," said Ian Wilmut, one of the team from the Roslin Institute
The realization that this was not the case came after the discovery by Ian Wilmut and Keith Cambell of a method with which to synchronize the cell cycles of the donor cell and the egg cell. Without synchronized cell cycles, the nucleus would not be in the correct state for the embryo to accept it. Somehow the donor cell had to be forced into the Gap Zero, or G0 cell stage, or the dormant cell stage.
The process involves the following steps:
- First, a cell (the donor cell) was selected from the udder cells of a Finn Dorset sheep to provide the genetic information for the clone. For this experiment, the researchers allowed the cell to divide and form a culture in vitro, or outside of an animal. This produced multiple copies of the same nucleus. This step only becomes useful when the DNA is altered, such as in the case of Dolly, because then the changes can be studied to make sure that they have taken effect.
- The donor cell is grown in a Petri/culture dish.
- A donor cell was taken from the culture and then starved in a mixture which had only enough nutrients to keep the cell alive.
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This culture dish barely has enough nutrients to keep the cell alive.
- This caused the cell to begin shutting down all active genes and enter the G0 stage. The egg cell of a Blackface ewe was then enucleated and placed next to the donor cell. One to eight hours after the removal of the egg cell, an electric pulse was used to fuse the two cells together and, at the same time, activate the development of an embryo.
- The enucleated egg cell and the mammary cell are fusing together.
- This technique for replicates the activation provided by sperm is not completely correct, since only a few electrically activated cells survive long enough to produce an embryo.
- If the embryo survives, it is allowed to grow for about six days, incubating in a sheep's oviduct. It has been found that cells placed in oviducts early in their development are much more likely to survive than those incubated in the lab. Finally, the embryo is placed into the uterus of a surrogate mother ewe. That ewe then carries the clone until it is ready to give birth. Assuming nothing goes wrong, an exact copy of the donor animal is born.
- This newborn sheep has all of the same characteristics of a normal newborn sheep.
Cloning has the possibility of being able to treat many diseases such as Parkinson’s, Alzheimer’s and Leukaemia. The treatment would involve the cloning of human stem cells, which have the capacity to grow into any type of tissue. These cells would then be treated with growth factors to form the cell type required, such as blood producing cells for treating leukaemia. ‘Lu Guanxiu…said last week she had created more than 80 embryos containing the genetic blueprint of an existing adult…Lu also disclosed that she had created cultures of human cells capable of providing “spare parts” for a variety of fatal human diseases.’ – The Sunday Times Jan 26 2003
As our knowledge of the human genome grows, it may be possible in the future to remove hereditary diseases before children are born or even going as far as choosing a child’s gender or eye colour. Many people are scared of the repercussions of such actions, that they would destroy genetic diversity, and that it isn’t much different from Hitler’s ‘ethnic cleansing’. They also feel we are taking ‘Gods’ work into our own hands, ‘For the first time we are not faced with the lamb of God, but the Lamb of Man’ – Daily Mail Feb 14 1997.
Human cloning is currently illegal in Britain, however, there are many countries in which it is not against the law. People are now worried of the dangers of cloning because of the apparent premature aging and the death of Dolly the sheep, as well as the number of failures it took before Dolly was created. This in itself holds major moral issues against the cloning of humans. Dr Wilmut himself, creator of Dolly has blasted ideas of human cloning, describing it as ‘extremely cruel’. He warned that four years of experiments on animals had shown the cloning technique to be deeply flawed, with many miscarriages and deformities.
It is uneasy to see now what future outcomes cloning may bring, but it easy to see it could have many positive effects, such as the treatment of diseases, but I believe a line must be drawn when we are moving from necessity to convenience and into the realm of genetically enhanced livestock and designer babies.