Pork on the clone
Xena, a cloned pig, is causing a stir amongst scientists who believe there is a possibility that genetically modified organs from cloned animals could be used someday in human transplants. The team of researchers, from Japan and the USA, took genetic material from the skin cells of a foetal pig and injected it into an egg stripped of its own DNA, the part of a cell that contains its genetic information. The egg was then transplanted into a surrogate mother. The scientists were able to check that the growing piglet was a clone rather than the surrogate's daughter using DNA analysis and observation (Xena has a dark coloured coat, whereas her surrogate mother is white). The research team hopes someday to be able successfully to refine the technique to genetically modify the cells from which pigs like Xena are cloned to produce a supply of pig organs that are acceptable for human transplants (a techniques known as xenotransplantation). The technique used to clone Xena is similar to that used by scientists at the Roslin Institute in Edinburgh, where the infamous Dolly the sheep became the first animal to be cloned in 1997. This new development is certain to re-ignite the debate on whether the cloning is ethically and morally acceptable, or indeed safe. In particular there are likely to be discussions on the probability of increasing the risk posed by retroviruses - diseases that are passed from animals to man - through xenotransplantation.