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Of Cats and Clones |
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In December 2004, a tabby kitten named Little Nicky made headlines for being the first cloned-to-order pet in the United States. The original Nicky was a cat that died at the age of 17 years. His owner, Julie, chose to have some of Nicky’s tissue “banked” so that he could be cloned. The company that produced Little Nicky, California-based Genetic Savings & Clone, Inc., also funded the creation of the very first cloned cat, CC, in 2002, and made the first cloned pet cats, Tabouli and Baba Ganoush, in the United Kingdom earlier in 2004. Cloning pets should be a very profitable business indeed: Little Nicky cost Julie $50,000. How do you make a clone like Little Nicky? The first mammal to be cloned from a somatic (body) cell of an adult was Dolly the sheep. She was made in 1996 at the Roslin Institute in Scotland, using a technique called somatic cell nuclear transfer. In this technique, the nucleus of a cell from a donor’s body is combined with an enucleated egg (one with its nucleus removed) from a female of the same species, and the resulting cell is stimulated to start dividing and grow into an embryo. The embryo is then placed in the uterus of a surrogate mother to continue its development. Although additional sheep, as well as pigs, cattle, goats, horses, rabbits, and mice, have been cloned using somatic cell nuclear transfer, one problem with this method is the low survival rate. Most embryos do not survive long enough to be implanted in a surrogate mother. And of those that do, almost one-quarter of the clones born have health problems so severe that they do not reach adulthood. These problems are thought to stem from the fact that the donor cell has already differentiated, and as a result its nuclear material is structurally different from that in a fertilized egg with respect to associated proteins. Some of the proteins associated with the nuclear chromatin may get carried over to the enucleated egg, where they interfere with development. CC was made using somatic cell nuclear transfer, but most consumers probably would not opt for this technique for cloning their pets because of its low success rate. In 2003, a new cloning technology known as chromatin transfer became available. In chromatin transfer, the chromatin is made to condense, much as it would prior to cell division. The condensed chromatin is treated to remove any extraneous materials prior to being injected into the enucleated egg. This method has resulted in a greater rate of cloning success, and was used to create Tabouli, Baba Ganoush, and Little Nicky. It is likely that there will be many more cloned pets. In fact, Genetic Savings & Clone looks to clone up to 50 cats over the next year, and plans to include dogs in the near future. Questions
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