American Horse Cloning Project Successful

America's first cloned horse turned six weeks old today, according to Texas A&M University (TAMU) researchers who partnered on the successful cloning venture with French scientist Dr. Eric Palmer of Cryozootech. The colt, named "Paris Texas," was produced from skin cells of a European performance stallion, and the active colt is healthy and steadily growing at TAMU.


Above, North America's first horse clone, "Paris Texas," and the grade mare who carried him to term, "Greta." Below, Drs. Katrin Hinrichs of Texas A&M and Eric Palmer of Cryozootech, who collaborated on the cloning project.


Katrin Hinrichs, DVM, PhD, Dipl. ACT, professor in the College of Veterinary Medicine at TAMU, led the cloning team on the project. She described Paris Texas as follows: "He's bay with a big white blaze, beautiful eyes, and four white stockings. He's real forward, a real nice foal. Everything is completely normal about him.

"Dr. Palmer took a small piece of skin from the donor animal and grew the cells up in culture and froze them, and he shipped them to us," said Hinrichs. "We did the cloning procedure here, cultured the embryo, and transferred it to one of our recipient mares, who foaled here in the hospital."

The owner of the donor horse from which skin cells were used to produce the clone wishes to remain anonymous. Cryozootech has cells from a variety of high-performance horses in Europe. Since researchers at TAMU were already doing the cloning research, a natural partnership formed between the French company and TAMU to complete this project. Paris Texas is the fourth equine clone to be born in North America, but he is the first horse foal (the other three were mules) and the first to be cloned from adult cells in North America. The mule clones were produced from cells from a fetus.

The TAMU team does all of its cloning work in vitro, or in the laboratory. Rather than getting oocytes (eggs) from mares right before they ovulate (the procedure used to produce the mule clones), TAMU researchers harvest oocytes from mares at other points in the cycle and mature them in an incubator. The scientists then perform nuclear transfers, in which they remove the nucleus from an egg cell (containing the cell's genetic material) and place a donor cell into the enucleated egg. The eggs are then activated, or stimulated to start dividing to form an embryo. Resulting cloned embryos are cultured in the laboratory for seven days, and once they are deemed ready, the scientists transfer  them nonsurgically into the recipient mare's uterus just as they would in normal embryo transfer procedures.

About 400 oocytes were cultured during the TAMU project, and the cloning process produced six embryos. Only one pregnancy resulted, and this was carried to term. The grade mare that carried the clone (Greta) has been a part of the reproduction herd at TAMU for about four years.

The colt will be used as breeding stock in Europe. "We're looking for a way to save valuable genetics," said Hinrichs. But cloned foals are unlikely to be competitors. "There are so many variables in the environment that a cloned foal has-Paris Texas  was in a petri dish in an incubator for the first seven days of his life," she added. "He was small at birth--about 60 pounds. Sometimes smaller foals don't achieve the adult proportions that they would have. But this horse, genetics-wise, should produce exactly the same sperm and should be able to sire foals with the same genetic makeup as the donor animal."

TAMU has several pregnancies from cloned embryos that are currently gestating and due for arrival in 2006. All were produced using donor cells from American horses. Hinrichs said, "We're so excited about what we're learning about the horse oocyte. We're looking at different methods for treating the donor cells before the nuclear transfer procedure and activating the egg afterward, looking at more ways to build on our results of the study that produced Paris Texas."

About the Author

Stephanie L. Church, Editor-in-Chief

Stephanie L. Church, Editor-in-Chief, received a B.A. in Journalism and Equestrian Studies from Averett College in Danville, Virginia. A Pony Club and 4-H graduate, her background is in eventing, and she is schooling her recently retired Thoroughbred racehorse, Happy, toward a career in that discipline. She also enjoys traveling, photography, cycling, and cooking in her free time.

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