What is somatic cell nuclear transfer?
Somatic cell nuclear transfer is a laboratory technique used for creating an ovum with a donor nucleus. It can be used in many different areas of research and for different types of medicine. It is often used in embryonic stem cell research and in regenerative medicine, where it is referred to as therapeutic cloning. Somatic cell nuclear transfer can also be used in the first step of reproductive cloning.
In somatic cell nuclear transfer the nucleus which contains all of the organisms DNA is removed and the remainder of the cell is discarded. At the same time the nucleus of an egg cell is removed. The nucleus of the somatic cell is then inserted into the enucleated egg cell, so the egg cell now has the nucleus of the somatic cell. After this insertion, the the somatic cell nucleus is reprogrammed by the host cell. This cell is then given a shock which begins the process of division. After many mitotic cell divisions whilst the cell cultured, the single cell forms a blastocyst which is the early stage of an embryo containing roughly 100 cells with almost identical cells to the original organism.
In somatic cell nuclear transfer the nucleus which contains all of the organisms DNA is removed and the remainder of the cell is discarded. At the same time the nucleus of an egg cell is removed. The nucleus of the somatic cell is then inserted into the enucleated egg cell, so the egg cell now has the nucleus of the somatic cell. After this insertion, the the somatic cell nucleus is reprogrammed by the host cell. This cell is then given a shock which begins the process of division. After many mitotic cell divisions whilst the cell cultured, the single cell forms a blastocyst which is the early stage of an embryo containing roughly 100 cells with almost identical cells to the original organism.
examples of somatic cell nuclear transfer
Dolly the sheep is perhaps the most famous cloned animal of all time. She was cloned at the Roslin Institute in Scotland on the 5th of July 1996. Animal cloning from adult cells is far more difficult than from an embryonic cell. Which is why when Dolly was produced, the only lamb from 277 attempts it was a major step in science for the whole world.
Scientists used an udder cell from a six year old Finn Dorset white sheep. The scientists had to find a way to reprogram the udder cells which was needed to keep them alive but to stop them from growing anymore, they did this by altering the growth medium (which is like the 'soup') in which the cells were kept. Then the scientists injected the cell into an unfertilised egg cell which was enucleated and made the cells fuse through electrical pulses. The egg cell was from a Scottish blackface ewe. When the cells from the white sheep and blackface ewe the team needed to make sure that the cells would develop into an embryo. The cell was cultured for 6/7 days to see whether it would divide and develop the way that a normal cell would before it was implanted into a surrogate mother which was another Scottish blackface ewe. Dolly was born 148 days later.
Once Dolly was born she lived a very pampered life at the Roslin Institute in Scotland. Dolly mated and reproduced normal offspring proving that clones are able to reproduce. Although Dolly seemed like a normal sheep she aged much quicker due to the fact that the DNA in the nucleus wraps up in chromosomes and shortens with each replication and her DNA was not from an embryo but an older sheep. Nor was Dolly entirely identical to her genetic mother as the mitochondria which are kept out of the nucleus were inherited from the egg donor. Dolly suffered from terrible arthritis in a hind leg joint and also from sheep pulmonary adenomatosis, a virus induced lung tumour which is common amongst sheep raised indoors. Dolly was euthanised on the 14th February 2003 at the age of 6, sheep can live up to roughly 11/12 years of age.
Scientists used an udder cell from a six year old Finn Dorset white sheep. The scientists had to find a way to reprogram the udder cells which was needed to keep them alive but to stop them from growing anymore, they did this by altering the growth medium (which is like the 'soup') in which the cells were kept. Then the scientists injected the cell into an unfertilised egg cell which was enucleated and made the cells fuse through electrical pulses. The egg cell was from a Scottish blackface ewe. When the cells from the white sheep and blackface ewe the team needed to make sure that the cells would develop into an embryo. The cell was cultured for 6/7 days to see whether it would divide and develop the way that a normal cell would before it was implanted into a surrogate mother which was another Scottish blackface ewe. Dolly was born 148 days later.
Once Dolly was born she lived a very pampered life at the Roslin Institute in Scotland. Dolly mated and reproduced normal offspring proving that clones are able to reproduce. Although Dolly seemed like a normal sheep she aged much quicker due to the fact that the DNA in the nucleus wraps up in chromosomes and shortens with each replication and her DNA was not from an embryo but an older sheep. Nor was Dolly entirely identical to her genetic mother as the mitochondria which are kept out of the nucleus were inherited from the egg donor. Dolly suffered from terrible arthritis in a hind leg joint and also from sheep pulmonary adenomatosis, a virus induced lung tumour which is common amongst sheep raised indoors. Dolly was euthanised on the 14th February 2003 at the age of 6, sheep can live up to roughly 11/12 years of age.
pros of cloning
Dolly was created at the Roslin Institute as part of research into producing medicine in the milk of farm animals. Researchers and scientists have been able to successfully transfer human genes which produce useful proteins into sheep and cows. An example of this would be the blood clotting agent factor IX to treat haemophilia or alpha -1- antitrypsin to treat cystic fibrosis, which is an inherited condition when the lungs and digestive system can be clogged with a thick, sticky mucus. Inserting these genes into animals is a difficult and laborious process; cloning allows researchers to only do this once and clone the resulting transgenic to build up a breeding stock.
This research of cloning technology has led to new ways and developments in producing medicines and is thus furthering our understanding of development and genetics.
This research of cloning technology has led to new ways and developments in producing medicines and is thus furthering our understanding of development and genetics.
cons of cloning and the ethical issues
Animal cloning and cloning itself brings about many arguments and controversies. One main argument against cloning is into the argument of humans playing God. Just how far should humans be able to interfere with bringing about new life and altering organisms. Altering life forms is argued by many that humans are surpassing the laws of naturing thus consequently leading humans into works that become 'unnatural'.
Not only can it be argued that this is unnatural but it also brings back the fear of the unknown. Many people argue that playing with genetics is dangerous and a step into the unknown. If people can now clone animals what else will people soon start to clone? What will be the next step?
Another large argument against cloning is the fact that the majority of cloning attempts end in failure, you do not know how the clone will deal with life or what sort of issues may arise when the clone develops further.
A genetic argument against cloning is that a larger gene pool is good and cloning does not enlarge the gene pool. Genetic variation is good within the human race so if cloning were to advance into human cloning this would be bad.
Not only can it be argued that this is unnatural but it also brings back the fear of the unknown. Many people argue that playing with genetics is dangerous and a step into the unknown. If people can now clone animals what else will people soon start to clone? What will be the next step?
Another large argument against cloning is the fact that the majority of cloning attempts end in failure, you do not know how the clone will deal with life or what sort of issues may arise when the clone develops further.
A genetic argument against cloning is that a larger gene pool is good and cloning does not enlarge the gene pool. Genetic variation is good within the human race so if cloning were to advance into human cloning this would be bad.