Dolly’s Cloning Likely Didn’t Cause Premature Aging

A new analysis of Dolly’s skeleton suggests the cloned sheep’s arthritis did not lead to her death. 

By Katarina Zimmer | November 24, 2017


Dolly, preserved at the National Museums of ScotlandWIKIMEDIA, TIMVICKERSDolly the sheep, who in 1996 became the first mammal to be cloned from an adult cell, may have died of natural causes, reports a new study published yesterday (November 23) in Scientific Reports.

Dolly died of an infection at 7 years old, which is considered young for a sheep. She was reported to show signs of severe arthritis in her knees at the time of her death, which raised suspicion amongst scientists that her early death was driven by premature aging caused by the cloning process itself.

To shed light on the issue, University of Nottingham developmental biologist Kevin Sinclair and a team of veterinarians undertook a new analysis of Dolly’s skeleton, comparing it with the bones of her daughter Bonnie and of two sheep cloned from differentiated cells, named Megan and Morag. X-rays showed that the two older cloned sheep, Bonnie and Megan, had more bone damage compared to Dolly. Morag, who died at a younger age, had less damage. The tendency for arthritic damage to increase with age is indicative of a normal aging process, the researchers argue.

These findings are in line with a previous study led by Sinclair that showed that Dolly’s cloned sisters had aged normally, with similar musculoskeletal and metabolic health as non-cloned sheep. Taken together, the results suggest that concerns about prematurely aging clones might be unfounded, and that the cloning process likely wasn’t to blame for Dolly’s arthritis. Instead, Sinclair and his colleagues believe it might have been caused by her giving birth to six lambs, as pregnancy can increase the likelihood for developing arthritis in sheep.

“We wanted to establish once and for all that cloned animals that survive and [make it] into old age are normal,” Sinclair told The Scientist earlier this year.

See “Study: Cloned Sheep Age Normally

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Avatar of: Shan-Lu Liu

Shan-Lu Liu

Posts: 1

November 24, 2017

Dolly the sheep died of lung cancer becasue of a retrovirus (JSRV) infection. This should have been clear made in this story. 

See below the link:

"After Dolly gave birth to her last lambs in September 2000, it was discovered that she had become infected by a virus called Jaagsiekte sheep retrovirus (JSRV), which causes lung cancer in sheep. Other sheep at The Roslin Institute had also been infected with JSRV in the same outbreak.

In 2001, Dolly was diagnosed with arthritis after farm staff noticed her walking stiffly. This was successfully treated with anti-inflammatory medication, although the cause of the arthritis was never discovered.

Dolly continued to have a normal quality of life until February 2003, when she developed a cough. A CT scan showed tumours growing in her lungs and the decision was made to euthanise Dolly rather than risk her suffering. Dolly was put to sleep on 14th February 2003, at the age of six."

Avatar of: dumbdumb


Posts: 99

November 25, 2017

considering that Dolly was most likely a clone derived from a pluripotent stem cell of the mamary gland's pregnant donor rather than an adult differentiated one, the findings should reflect what seen in other "regular" cloned mammals.

Scraping the bottom of Dolly's barrel, and still gettting published in Nature. Good for them

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