Mule cloned
Racehorse replicas could follow their stubborn cousins.
30 May 2003
HELEN PEARSON

 
Two mules can't make another, but cloning can.
© University of Idaho/P. Schofield
 
 

Scientists and a mule-racing philanthropist are celebrating the birth of the first cloned mule - alive and kicking. The new arrival is the first equine animal to be cloned, and the technique that created him could prove valuable to racehorse breeders.

The mule, called Idaho Gem after the state of his birth, lives up to the breed's stubborn reputation, says proud team leader Gordon Woods of the University of Idaho in Moscow. After a recent photo shoot, "it took six of us to capture him", he says.

Idaho Gem's creation was partly motivated and financed by Don Jacklin, president of the American Mule Racing Association. "I'm so excited, I'm in the sky," he enthuses. Mules - a cross between a horse and a donkey - are sterile, so winning animals cannot be bred.

Researchers now hope to use the mule-cloning technique to produce identical copies of champion jumpers or show-horses. Most are no good for breeding - they are often castrated, or gelded, to calm their natural friskiness.

With huge race jackpots at stake, horse breeders would not baulk at the $50,000-100,000 price tag for cloning a valuable animal for breeding, says reproductive biologist Katrin Hinrichs of Texas A&M University in College Station. Breeders can already pay stud fees as high as half a million dollars to mate mares with a winning thoroughbred stallion.

Endangered horse species and their relatives, such as zebras and wild asses, might also be rescued by cloning, Hinrichs predicts. But it remains to be seen whether Idaho Gem will develop health problems later in life. Some other cloned animals - most notably Dolly the sheep - have shown signs of premature ageing.

Night mare

Despite several efforts around the world, equines have proved particularly tricky to clone following the recipe that made Dolly. After many failed attempts, cloning expert Robert Godke of Louisiana State University in Baton Rouge had admitted defeat. "I'm a whipped dog," he says.

 
Idaho Gem is the sole survivor from 305 implanted embryos.
© University of Idaho/P. Schofield
 
 

Woods' team eventually succeeded by boosting calcium levels inside the eggs and embryos - this may trigger them to divide and grow, the researchers believe. The team took DNA from a mule fetus, shot it into a horse egg emptied of its own DNA, and implanted the embryos into mares1.

Despite this success, Idaho Gem is all that the team has to show for five years' work and 305 implanted embryos - although another two cloned mules are expected in the summer. And Hinrichs says that the first cloned horse - a copy of Skip, her own daughter's 20-year-old pet - should be born in November.
 
 
References
Woods, G.L.. et al. A mule cloned from fetal cells by nuclear transfer. Sciencexpress, published online, doi:10.1126/science.1086743 (2003). |Article|