cannot be reprogrammed to make a whole newbody. Dolly was created by using a technique called nuclear transfer. The Roslinscientists took a cell from the udder of an adult sheep and cultured it for several weeks. Then they harvested an unfertilized egg from a second sheep and removed the part thatcontains the genetic material (nucleus) after starving them for several days. By starvingthe donor cells for five days before extracting their nuclei, Wilmut and Campbell madethe nuclear DNA susceptible to being reprogrammed once placed in an egg. Electricitywas used to combine the two cells. The egg then began dividing as a "naturally"fertilized egg would, becoming an embryo. That embryo was implanted into a thirdsheep, a surrogate mother that gave birth to Dolly. Dolly was, therefore identical to thesheep that donated the udder cell. It was said to be impossible. Many animal development experts now suspect that genetically duplicatinghumans is possible, especially as Donald Wolf of the Oregon Regional Primate ResearchCenter has already cloned rhesus monkeys from embryonic cells. Tetra, a rhesus monkeyborn in 1999, was cloned by researchers at the Oregon Regional Primate Research Centerusing a different procedure from the one that made Dolly. Researchers used embryosplitting, a technique that makes Tetra a clone of her sisters, rather than a clone of anadult mammal. Researchers fertilized an egg from a female monkey with the sperm of amale monkey to make an embryo. When the embryo divided into eight, researchers splitit into four identical two-celled embryos. Each two-celled embryo was implanted into asurrogate mother. Only one embryo survived, and Tetra was born. Tetra is geneticallydifferent from her mother and father, but is identical to the other three embryos if theyhad survived.Animals engineered to carry genes from species other than their own can be madeto produce a wide variety of proteins that could be sold as drugs, as ...
