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17 April 2014 12:48 pm ,
Vol. 344 ,
Officials last week revealed that the U.S. contribution to ITER could cost $3.9 billion by 2034—roughly four times the...
An experimental hepatitis B drug that looked safe in animal trials tragically killed five of 15 patients in 1993. Now,...
Using the two high-quality genomes that exist for Neandertals and Denisovans, researchers find clues to gene activity...
A new report from the Intergovernmental Panel on Climate Change (IPCC) concludes that humanity has done little to slow...
Astronomers have discovered an Earth-sized planet in the habitable zone of a red dwarf—a star cooler than the sun—500...
Three years ago, Jennifer Francis of Rutgers University proposed that a warming Arctic was altering the behavior of the...
- 17 April 2014 12:48 pm , Vol. 344 , #6181
- About Us
Mary Had a Little ... Clone
24 February 1997 8:00 pm
Creating a whole new organism from a single cell has been more the stuff of science fiction than of science. Not anymore. Scientists have cloned a lamb using a cell nucleus taken from an adult ewe's udder, according to a report scheduled to appear later this week in Nature. The breakthrough has generated a fierce backlash from ethicists and others who fear the prospect of human cloning.
Embryologist Ian Wilmut and his colleagues from Scotland's Roslin Institute first grew the udder cells in laboratory dishes, then put nuclei from those cells into ova whose DNA had been removed. They found that in the egg, the transferred genome reverted to embryonic patterns of gene expression, prompting the egg to begin dividing. The viable embryo was then placed in the womb of the ewe that had produced the egg.
Wilmut's 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 point in their lives will do the job. In addition to the lamb from a 6-year-old ewe's mammary tissue, four offspring were produced with nuclei from 9-day-old embryos and three from the skin cells of 26-day-old fetuses.
Others have made new organisms, primarily amphibians and mice, using embryonic nuclei, but failed when they used cells from adults. "Now we have convincing evidence that it's doable," says embryo researcher Colin Stewart of the National Cancer Institute-Frederick Cancer Research and Development Center in Frederick, Maryland.
It had been thought that in mature somatic cells, some genes necessary for development were permanently turned off, even lost. Thus the group's success was a "big surprise," says Wilmut. "The mechanisms which regulate gene expression are more labile than might have been imagined." Eventually, says Wilmut, he hopes to use nuclear transplantation to create sheep, or cattle, with specific genes added to their genomes.
Theoretically, people too could be cloned: Just imagine how much someone would pay for a basketball team fielding five versions of Michael Jordan. Wilmut told ScienceNOW that his group is ethically opposed to human cloning. "We have no idea whether it will work [in people]," he adds. Activists, however, are taking steps to thwart that possibility. For instance, biotech critic Jeremy Rifkin of the Foundation for Economic Trends announced yesterday that his group, along with some religious leaders and nongovernmental organizations, "is determined to mount a global effort in opposition to human cloning and will seek legislation to outlaw this technology in every nation." Several countries--including Germany and the United Kingdom--have laws on the books forbidding human cloning, but the United States is not among them.