Cloning Allows Scientists to Increase Impact of Genetic Traits

MOSCOW, Idaho – Cloning has occurred in nature for billions of years in plants and some lower animals. Cloning is asexually producing offspring that are genetically identical to a parent plant or animal. For example, a plant grown from a leaf cutting is a clone of the original plant because they are genetically identical.

In the laboratory, scientists use somatic cell nuclear transfer techniques to produce animals with genetic material identical to just one parent. At present, 10 species have been successfully cloned, among them cattle, pigs, sheep, mice and cats.

Using microsurgery techniques, scientists remove the nucleus from an egg cell, which contains the cell’s genetic material, creating an enucleated egg. The genetic material from a somatic cell – which can be any body cell other than an egg or sperm cell – is removed from the cell and injected into the enucleated egg. An electric pulse fuses the egg cell and new genetic material. The cell is then treated in media that allows it to develop into an embryo that can be implanted in a surrogate mother’s womb and carried to term.

Cloning will not replace sexual reproduction in animals, but allows scientists to increase the impact of important genetic traits in populations of animals and may be the only means of reproducing some animals. For example, cells from endangered animals may be used to increase populations of some species, but cloning them also requires surrogate mothers that are genetically similar to carry the embryos to term.

The birth of Idaho Gem, the first cloned mule, presents other important opportunities. Mules are crosses of horses and donkeys and, like most hybrids, are sterile. The only way to produce genetic copies of an outstanding mule is through cloning.

Understanding the unique requirements for developing cloned equine embryos may also open the way to cloning horses with important genetic traits. For example, Funny Cide, this year’s winner of the Kentucky Derby and Preakness is a gelding, a genetic dead end unless cloning could produce copies of him.