Noah's New Ark

Noah's Ark has set sail again, crossing stormy scientific waters and buffeted by winds of controversy. Unlike the Old Testament vessel, however, today's metaphorical ark is not carrying threatened animals two by two to safety. Rather, if it lives up to its billing, it could produce potentially unlimited numbers of endangered creatures.

In the updated story, though, Noah is not the skipper of the rescue project. Instead, it's the name given in advance to the clone of a dead gaur, an endangered wild ox found in India, Bangladesh and Southeast Asia. The new Noah is expected to be born any day now to Bessie, a cow living on a farm near Sioux City, Iowa. Cows have given birth to gaurs before, but this is the first time that one animal species is acting as surrogate mother to a clone--an exact genetic duplicate--of a different species. "The gaur is developing well," says Emily Poe, a spokeswoman for Advanced Cell Technologies. A small biotechnology company based in Worcester, Mass., ACT is using a novel cross-species nuclear-transfer technique that could usher in what it sees as a new era in conservation.

Bessie's ultrasound tests may look good, but is the concept itself a sound one? Robert Lanza, ACT's vice president of medical and scientific development, says the technique is not a panacea but "presents exciting possibilities" that may help rescue endangered species and perhaps even reverse extinctions. Other scientists aren't so sure. They argue that such high-tech approaches are unlikely to make a significant contribution to the support of vulnerable species, especially if their habitats have been destroyed.

Still, if Bessie's little gaur is delivered safely, the birth will come as a boost to many biologists in the U.S. and Europe who are engaged in a range of "assisted reproduction" conservation strategies. These include artificial insemination and in vitro fertilization. In particular, though, Noah's arrival will hearten the scientists at ACT, who recently signed a deal with Spanish officials to attempt to clone the bucardo, an extinct mountain goat native to the Pyrenees. The last bucardo died a year ago, struck by a falling tree in its final habitat, northern Spain's Ordesa National Park. Scientists had already preserved a quantity of its cells, and ACT hopes to transfer them into other goats' eggs, perhaps later this year.

The cloning technique used with Bessie--the only cow in the experiment to carry an embryo into late pregnancy--is a variation of the procedure that created Dolly the sheep, the world's first cloned mammal. A needle is jabbed through an egg's protective layer and used to remove the egg's nucleus, containing most of a cell's genetic material. A second needle is used to inject a whole cell under the egg's outer layer. To complete the process, an electrical current fuses the new cell to the egg. The embryo starts to divide until, within days, the mass of cells grows to about 100 and is big enough to be implanted in the surrogate mother's uterus.

The creation of Noah began with the fusing of skin cells from a male gaur and 692 cow eggs. Just 81 grew into blastocysts (clumps of cells suitable for implantation), and 42 of those were inserted into 32 cows, of which eight became pregnant. Two of the fetuses were later removed for study, while five cows sustained spontaneous abortions. Only Bessie and Noah are left.