URL: http://www.nationalpost.com/artslife.asp?f=990527/2646887.html
May 27, 1999
Dolly's 'telomeres' showing their age
Roger Highfield
The Daily Telegraph
LONDON - Dolly the cloned sheep was born old, a discovery that could
hamper plans to use cloning to grow a patient's own organs and tissue
for transplant.
She was cloned from a cell taken from a six-year-old sheep. In an
article in the journal Nature, released today, the scientists who
pioneered the procedure report that the ends of Dolly's chromosomes
appear to be short, suggesting she inherited some of the wear and tear
endured by her mother.
The results are reported by PPL Therapeutics and the Roslin Institute,
the Edinburgh-based groups that engineered Dolly nearly three years ago.
Alan Colman, research director of PPL and co-author of the report, said
that the finding confirms earlier suspicions. He said the ageing problem
could make it harder to carry out "therapeutic cloning" where cells from
a patient are cloned and grown to produce tissue or an organ for
transplant.
He said that the findings provide "another good piece of evidence to
make people shy away from human cloning,'' which is banned in the United
Kingdom and is expected to be banned in Canada by legislation to be
introduced this fall.
The cloned animals had fractionally shorter "telomeres" than normal
sheep of the same age. Telomeres are genetic sequences at the end of
chromosomes that "cap" them and protect them from fraying. They have
long fascinated researchers, because they are believed to be involved in
the ageing process.
As one would expect, Dolly, who was cloned from an adult sheep, appeared
to have the shortest telomeres, followed by animals 6LL6 (Tuppence) and
6LL7 (Taffy), which were cloned from cells taken from an embryo and
foetus, respectively.
Colman said that it is not known if telomere shortening causes ageing or
reflects it. However, Dolly does not show any signs of premature ageing.
He added that the find should not hamper efforts to clone animals -- a
procedure that uses foetal cells that are so young their telomeres have
not significantly shortened.
Copyright © Southam Inc.
--
Judith Richards, London, Ontario, Canada
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