About Dolly the Sheep

Dolly the Sheep achieved fame by being the first mammal to be cloned using nuclear transfer. Dolly lived from 1996-2003. She was cloned by Ian Wilmut and Keith Campbell in Edinburgh, Scotland at the Roslin Institute. Since the cells that were used to create Dolly came from a mammary gland, they named her Dolly after singer Dolly Parton.

Cloning Facts

• Though Dolly was the first mammal to be cloned using adult cells, scientists have cloned plants, amphibians and cows using embryonic cells. Even identical twins are considered embryonic clones. In fact, the scientists who created Dolly cloned two other sheep, Megan and Morag, from embryonic cells a year before Dolly.

Process

• The world did not find out about the cloning of Dolly until a year after her birth. The scientists at the Roslin Institute attempted 277 times to clone sheep from adult cells and Dolly was the only success. Taking the nucleus of a Finn Dorset sheep, the scientists reprogrammed the donor cells to keep them alive but cease the growing process. They then injected the cells into an egg cell without a nucleus. Then they used electricity to fuse the cells. After culturing the egg cell for a week, they implanted it into a surrogate, a Scottish Blackface ewe.

Life

• Dolly spent her entire life at the Roslin Institute, under the observation of scientists. They allowed her to breed with a ram and she had six lambs. All of her offspring were considered to be normal sheep. After 5 years, Dolly began to experience troubles with walking. She was diagnosed with arthritis and the scientists put her on anti-inflammatory drugs.

Death

• Scientists at the Roslin Institute put Dolly to sleep in 2003 after they diagnosed her with progressive lung disease. Death at the age of six is young for sheep and pundits blamed the cloning process for the early departure. However, the scientists at the Roslin Institute believe that the cloning process is not responsible. But, research has found that since the donor cells came from a sheep of 6 years of age, that Dolly's DNA was "older" than that of a newborn lamb. The average sheep lives around 12 years.

Beyond Dolly

• Scientists have continued to clone mammals since Dolly the Sheep. In 2005, a scientist from Korea cloned the first dog. In 2009, a Spanish scientist announced the cloning of the Pyrenean Ibex, an animal extinct since 2000. Though the baby Ibex died shortly after birth from a lung defect, its DNA had come from a frozen tissue sample, raising hopes that endangered and extinct animals can be resurrected in the future.