![[ image: width=150]](/olmedia/350000/images/_353617_tellomereimage150.jpg)
The possibility that the sheep may die early has been raised after a study of her genetics by some of the same scientists who created the clone in 1996.
A team from the biotechnology firm PPL Therapeutics in Scotland examined structures in Dolly's cells called telomeres.
They report in the journal Nature that the structures are slightly shorter than would be expected in a sheep of her age born normally.
There is some evidence that telomere length is linked to ageing. However, the researchers say it is currently impossible to predict precisely how long the world's most famous sheep will live.
"All we're saying is that yes, as we and others expected, this animal started off with shorter telomeres," Dr Alan Coleman, research director at PPL Therapeutics told the BBC.
"It doesn't necessarily follow that she will age prematurely because this link between the telomeres and ageing is not proven - it's just an interesting theory.
"In fact, if sheep like Dolly and other mammals made by this [cloning] technique are continually shown to be perfectly healthy and not age prematurely, that would just prove that the whole link between the telomeres and ageing is an unreliable one and not worth worrying about."
![[ image: width=150]](/olmedia/350000/images/_353617_dolly_bonny150.jpg)
Cell suicide
Telomeres are nubs of protein and nucleic acid that cap the ends of chromosomes, the structures in cells that bundle up all the DNA.
The telomeres are produced during embryonic development but start to crumble away as cells mature and divide. When the erosion is complete, so the theory goes, the cell commits suicide.
In recent US research, laboratory mice bred to have shorter telomeres went prematurely grey, got cancer more often and died early.
Dolly's shortened telomeres would seem to stem from two factors:
Dr Coleman says the research will need to be followed up on many more cloned animals. But from what they know already, he says he would not recommend cloning clones because this would only amplify any problems that might exist.
Exciting technologies
![[ image: width=150]](/olmedia/350000/images/_353617_cloningcell150.jpg)
The research also has important implications for the new stem cell technologies, now exciting huge interest. Stem cells are the "master" cells in the body which can become any type of tissue.
Scientists believe they can ally cloning and stem cells to create perfect-match transplant tissue.
They envisage, for example, leukaemia victims being able to provide their own bone marrow transplants.
But the cloning process involved in creating these replacement cells would have an effect on their telomeres.
"Undoubtedly they would go down dramatically," says Dr Alan Coleman. "If you put these cells back into a human, you would be asking yourself how long they would last. How would they behave if they have been having all this erosion taking place at the end of their chromosomes?"
He believes one thing is certain - Dolly and all the other clones now being created around the world will tell us a lot more about the lifecycle of cells and the ageing process.
Pig clone for the millennium
(13 May 99 | Sci/Tech)
Dolly goes to market
(27 May 99 | Sci/Tech)
Cloning may damage long-term health
(27 May 99 | Sci/Tech)
Scientists clone a goat
(26 Apr 99 | Sci/Tech)
Multiple monkey cloning attempt
(09 Apr 99 | Sci/Tech)
Roslin Institute
Society, Religion and Technology Project (Church of Scotland)
Cloning (New Scientist)
Dolly and Cloning (Time)
A Clone in Sheep's Clothing (Scientific American)
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