[ Download Full Article (PDF) ]

How does a days-old embryo signal its mother-to-be to prepare for pregnancy? In horses, the embryo releases a chemical signal, prostaglandin E2, to begin its journey to the womb and days later successfully signal its presence in the womb. Finding and tracking those chemical signals that begin soon after egg and sperm unite are vital to understanding equine fertility.

Northwest Equine Reproduction Laboratory scientists Dr. Gordon Woods, Dr. Dirk Vanderwall, who was then a graduate student in the laboratory, and others discovered and demonstrated the effect of prostaglandin E2 in pioneering studies of endocrinology in the horse.

Student scientist Jessica Williams plans to continue the quest to understand the chemical signaling between embryo and mare. A critical time during the establishment of pregnancy occurs after the embryo enters the womb.
Once the egg is released, the mare’s ovarian follicle collapses and becomes the corpus luteum, the endocrine structure that produces progesterone, the hormone essential for maintaining the pregnancy.

Earlier work showed that if the mare is not pregnant, or if the embryo fails to signal its presence to the mare, the mare’s uterine lining produces prostaglandin F2a, and that hormone essentially restarts the reproductive cycle. Prostaglandin F2a causes the corpus luteum to break down, ending progesterone production and the pregnancy, if she was pregnant.

“We’re going to try to identify the embryonic cycle that inhibits luteolysis,” said Vanderwall, who serves as Williams’ major professor. The work may lead to earlier detection of pregnancies and a less expensive early pregnancy test for horses.

Three of the world’s four equine clones, the three mule foals of Project Idaho, offer new ways to explore the question of nature versus nurture. Essentially identical triplets born to different surrogate mothers, the mules carry the same DNA. Are animals’, and our, fates determined mostly by our genes or does the environment play the greatest role?

As they grow to adulthood, Idaho Gem, Utah Pioneer and Idaho Star will help answer many questions. At birth, Idaho Gem was the heaviest with a birth weight May 4 of 107 pounds. Utah Pioneer was the lightest at 78 pounds June 9. Idaho Star weighed 87 pounds at birth July 27.

After six months, all three mules showed steady growth and robust vigor. Idaho Gem, the eldest, kept his lead as the largest, exceeding 500 pounds before his six-month birthday. Utah Pioneer weighed nearly 350 pounds and Idaho Star weighed more than 300 by December.

Their progress will be monitored and recorded throughout their lives with regular blood tests and almost daily visual exams. “From everything we can see and measure, they are normal, healthy and vigorous,” said Dr. Dirk Vanderwall of the Northwest Equine Research Laboratory.

All three mules appeared in different forums from late summer to late fall. IdahoGem appeared at the Western Idaho State Fair in mid August, then traveled to the California State Fair at Sacramento until Labor Day. Idaho Star took his turn in the limelight at the Eastern Idaho State Fair at Blackfoot in late August. Utah Pioneer traveled to Logan, Utah, in early October to appear at Utah State University’s Homecoming celebration to honor the accomplishment of Dr. Kenneth White. White, a Utah State University animal scientist and the somatic cell nuclear transfer cloning expert, was one of three principal scientists with Vanderwall on the Project Idaho team.

Dr. Gordon Woods, the Project Idaho team leader and NERL director, spent nearly three weeks with the mule clones during the many public events to explain Project Idaho’s goals and accomplishments. Woods estimated that 25,000 people took the opportunity to examine the clones close up and learn more about cloning and its potential payback for human health.