Creating a new organism from a single cell was more science fiction than science. Not anymore. Scientists have cloned a sheep using a cell nucleus taken from the udder of an adult sheep, according to a report is expected later this week Nature . The breakthrough has generated a fierce reaction from ethicists and others who fear the prospect of human cloning.
embryologist Ian Wilmut and his colleagues at the Roslin Institute Scotland first increased udder cells in laboratory dishes, then put the nuclei of these cells into egg cells whose DNA had been removed . They found that in the bud, the genome transferred back to embryonic pattern of gene expression, prompting the egg to start dividing. The viable embryo was then placed into the uterus of the ewe that had produced the egg.
Wilmut team first used this technique a year ago, producing lambs with nuclei transplanted from very early embryos. In their latest work, the group reports how cells taken from sheep at any time in their life will do the job. In addition to the lamb of the breast tissue of a sheep 6 years, four children were produced with cores 9 day old embryos and three from the cells of the skin 26 days fetus.
Others have new bodies, mainly amphibians and mice using embryonic nuclei, but failed when they used adult cells. "We now have strong evidence that it is feasible," said researcher Colin Stewart embryo Centre for Research and Development Frederick Cancer National Cancer Institute in Frederick, Maryland.
We thought that in mature somatic cells, certain genes necessary for the development have been transformed permanently, even lost. Thus the success of the group was a "surprise," says Wilmut. "The mechanisms that regulate the expression of genes are more labile than we could have imagined." Finally, Wilmut said he hopes to use nuclear transplantation to create sheep or cattle with genes added to their specific genomes
Theoretically, people could also be cloned. Imagine how much someone would pay for a basketball team fielding five versions of Michael Jordan. Wilmut said Science Now that his group was opposed to human cloning ethically. "We do not know if it will work [in people]," he added. Activists, however, take measures to counteract this possibility. For example, the critic Jeremy Rifkin Biotechnology of the Foundation on Economic Trends announced yesterday his group, as well as some religious leaders and non-governmental organizations, "is determined to mount a global effort opposed human cloning and will seek legislation to ban this technology in every nation. "Several countries - including Germany and the United Kingdom. - Have the laws on the books banning human cloning, but the United States is not among them
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