Scientists have cloned a calf from the sole remaining member of a herd that has been isolated from other cattle for more than a century, according to an article in today's Washington Post. The birth shows that cloning may help preserve rare breeds of animals and perhaps even save endangered species, David Wells of the Ruajura Research Center in Hamilton, New Zealand, told the Post.
The herd lived on one of the Auckland Islands, off the southern coast of New Zealand. In 1992, the New Zealand government destroyed the herd, which had descended from livestock that ranchers abandoned in the mid-1800s, to prevent degradation of the island's habitat. All that remained were semen collected from 10 bulls and a single female, called Lady, now 14 years old. Wells and his colleagues decided to try cloning because only once in the past 6 years did Lady become pregnant and produce a calf, and that was by in vitro fertilization. They wanted to preserve the herd's unique genetic makeup as the animals had survived the harsh island conditions--often eating seaweed--without any antibiotics or other amenities and, among other things, had evolved long bodies and short legs.
Wells's team first transferred nuclei from Lady to eggs taken from other breeds of cattle, a technique similar to those used to clone mice and the sheep Dolly. For the procedure, the researchers removed granulosa cells, which nourish maturing egg cells, from Lady's ovaries. Next they used a mild electric shock to fuse one of these cells with an egg cell. The DNA of that egg had been removed, allowing Lady's nuclei--and her genetic material--to guide development. The resulting embryos were transplanted into surrogate mothers.
The first clone, named Elsie, was born by caesarean section July 31. DNA fingerprint tests show she is a true clone, and several more clones are one the way, Wells told the Post. "It's really a good thing for nuclear transfer to see this application of this [cloning] technique," says Will Eyestone, with PPL Therapeutics in Blackburg, Virginia. "It's really going to change how [conservationists] think about preserving endangered species."