Cloning

History

The production of a live lamb from a cell from the mammary gland of an adult sheep turned over one of the basic ideas of developmental biology. Until Dolly was born, it was thought that once a cell had differentiated during embryonic life, the process could not be reversed.

As soon as the news of Dolly’s arrival broke, the Pope condemned the practice of cloning, and President Clinton ordered an immediate and rapid enquiry into the ethical and legal implications.

In 1998 the first human embryonic cells were isolated and made to divide in the laboratory (cell culture). This re-ignited the media’s interest in the possibility of human cloning, but also represented the first step in using stem cells to help cure disability and disease.

The possibilities

• use in research into basic developmental biology, e.g. to further our understanding of differentiation and how this can be reversed;
• use in testing of products, including new medicines: genetically identical animals would eliminate any error due to genetic difference;
• conserving useful characteristics in domestic animals, e.g. better meat or milk production in cattle;
   

Since Dolly was born, scientists around the world have successfully cloned more sheep, and also mice, cattle, goats, pigs cats and, after many unsuccessful events, the first equine species: a mule. However, the success rate of mammalian cloning is very low. You can read more about the cloning of new species here: 

Notice particularly the cloned kitten, Copy Cat (CC, or Carbon Copy) and her “mother”, Rainbow.

There has been no success to date for rabbits, rats or monkeys.

Knock Out Pigs.

Cloned pigs have been born  which have been genetically modified to “knock out” certain genes. These are the genes that make the pig organs reject if transplanted into humans. Pigs are thought to be a potential source for animal-to-human transplant (a process known as xenotransplantation) because they are easy to breed and their internal organs are a similar size to humans’.

You can read more about this ground-breaking medical research here:

 Ethical issues of cloning