Professors follow sheep cloning

Lisa Cassady

After running molecular tests on the world-renowned cloned sheep, Dolly, researchers from the Scottish Roslin Institute found that although Dolly is only three years old, her cells are nine years old.

Dolly was cloned from a 6-year-old ewe in 1996, and since then, scientists at Iowa State have been closely following the research.

Eric Henderson, professor of zoology and genetics, said new developments in cloning are important to future research.

“It is really not trivial research,” he said. “This kind of research has been done before on frogs. This is the first of its kind done on mammal cloning.”

According to a Washington Post article in May, some scientists theorize Dolly will die at an early age because her telomeres, genetic material that shortens as the cells divide and the animal ages, are shortening more rapidly than a normal sheep’s telomeres.

“I believe that this was a technological challenge but not a new scientific breakthrough,” Henderson said. “Scientists could theorize that this would happen. The experiment came long after the theories, and this only confirms them.”

The study suggests dividing a cell to form an embryo does not rebuild the telomere when the cell divides, therefore causing the cloned animal to age prematurely.

Chris Tuggle, associate professor in animal science, said he is unsure about Dolly’s chances of living an average lifespan.

“The jury is still out on this one,” he said. “I do not know if Dolly will die earlier because of her shortened telomeres. Dolly was taken from a sample of DNA that had been sitting in the petree dish for years. The DNA that she was made from was old; this could have affected her aging.”

However, Tuggle said if Dolly happens to die early, there is no way of pinpointing the cause because there are not enough sheep to verify the results.

“If Dolly dies early, you don’t know if it is telomeres because it is only one example,” he said.

According to the Post article, scientists from the Institute in Roslin are still studying the effects of telomeres on the gene equation; however, they theorize telomeres might cause the cell to divide but not rebuild.