Scientists are also interested in cloning because of its use in the development of animal organs for transplant into humans (xenotransplantation). Adding the knowledge they already have they would be able to clone pigs (achieved for the first time in march 2000) they would also have a reliable supply of donor organs.
The cloning of animals could also lead to a further understanding of the development of the embryo and aging. As well as the protection of rare and endangered species.
Dolly the sheep.
Dolly the sheep may be the worlds most famous clone but surprisingly she was not the first. Cloning is basically a process which leads to an end product of a genetically identical copy of an animal. The animals cloned before dolly included a frog, sheep, mouse and cows. Taking a cutting of a plant in your garden and putting it in rooting powder then placing it back into the garden is also producing a clone. Human identical twins could also be known as clones.
As we have just discovered that dolly was not the first animal to be cloned and of course looks just like any other sheep then why did we hear most about her and why was there so much concern? Dolly was actually produced from an adults cell rather than an embryo. This was a modern day scientific achievement but raised lots of ethical issues. Dolly was born in1996 and since that year other animals have also been cloned from a single adult cell such as cattle, pigs, mice and goats.
How was dolly produced?
Producing dolly from a single cell was going to be more difficult than taking a cutting from a plant. The scientists who produced dolly worked in the Roslin institute in Scotland, she was the only lamb to be produced from 277 attempts, this was a shock to scientists as it was broadcast on the news and put on the front of every newspaper as a major story all around the world. The cell that they used to produce dolly was from the udder of a 6 year old Finn Dorset white sheep. The nucleus of a cell contains almost all of a cells genes. They had to find a way of changing the cells so that they would continue to stay alive but somehow they had to halt its growth, the scientists achieved this by altering the cells “growth medium”. The scientists then injected the egg into an unfertilized egg cell which had had its nucleus removed then they made the two component part fuse by using electrical pulses. The unfertilized egg cell cam from a Scottish black faced ewe.
After the procedure was completed then the scientists had to make sure that the resulting cell would develop into an embryo. The scientists then cultured it for about a week to see if it would divide and develop normally, before implanting it into the surrogate mother, another Scottish blackface ewe.
The astonishing fact was that from 277 cell fusions, 29 early embryos developed and were implanted into 13 surrogate mothers. But only one pregnancy went to full term, and the 6.6kg Finn Dorset lamb 6LLS (alias Dolly) was born after 148 days.
