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5 December 2013 11:26 am ,
Vol. 342 ,
An animal rights group known as the Nonhuman Rights Project filed lawsuits in three New York courts this week in an...
Researchers have been hot on the trail of the elusive Denisovans, a type of ancient human known only by their DNA and...
Thousands of scientists in the Russian Academy of Sciences (RAS) are about to lose their jobs as a result of the...
Dyslexia, a learning disability that hinders reading, hasn't been associated with deficits in vision, hearing, or...
Exotic, elusive, and dangerous, snakes have fascinated humankind for millennia. They can be hard to find, yet their...
Researchers have sequenced and analyzed the first two snake genomes, which represent two evolutionary extremes. The...
Snake venoms are remarkably complex mixtures that can stun or kill prey within minutes. But more and more researchers...
At age 30, Dutch biologist Freek Vonk has built up a respectable career as a snake scientist. But in his home country,...
- 5 December 2013 11:26 am , Vol. 342 , #6163
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Cloned Mice Keep Dolly Company
22 July 1998 7:00 pm
As the first mammal cloned from an adult cell, Dolly was greeted first with awe and, later, with doubts, for some researchers wanted more proof that she was the real McCoy. Now they have it. A report in tomorrow's issue of Nature confirms for the first time that cloning from adult cells is not only possible but repeatable. These new experiments have so far yielded more than 50 cloned mice.
As with Dolly, the mice were cloned by putting nuclei from adult cells into eggs whose own DNA had been removed. The resulting cells were then triggered to develop into embryos, which were implanted in foster mothers. Dolly was produced by fusing the donor and egg cells and activating development with an electrical pulse, while Ryuzo Yanagimachi and his team at the University of Hawaii, Honolulu, injected nuclei into mouse eggs using a very fine needle. They then let the cells sit for up to 6 hours before triggering the eggs to develop by putting them into a culture medium containing strontium, which stimulates the release of calcium from the eggs' internal stores--the same signal that tells fertilized eggs it's time to start dividing.
Yanagimachi confirmed that the newborn mice had been cloned by comparing their DNA to that of the animals that provided the nuclei. It was identical. And the cloned mice seem normal--as were clones of clones and offspring of clones mated to each other. All told, "it's a very compelling paper," says Michael McClure, a cell biologist at the National Institute of Child Health and Human Development in Bethesda, Maryland.
Meanwhile, two other reports in the same issue describe DNA analyses proving that Dolly and the ewe she was cloned from are indeed genetically identical, as would be expected of clones. And in Japan, two calf clones born 5 July but not yet fully described in the scientific literature have apparently passed similar tests. Cloning is "a real phenomenon," comments Richard Schultz, a developmental biologist at the University of Pennsylvania in Philadelphia.