2/19/2009
Good Bye Dolly
The First Mammal
Cloned By Nuclear Transfer
The Telomeres of Dolly were
shorter
•
Dolly yielded new information about the cloning
process and how it can affect the clone and
could add data to the idea that telomere length
is connected to growing older. The researchers
reported that Dolly's telomeres were 20 percent
shorter than those of sheep who are not clones.
Is this a coincidence?
• Probably too early to tell at this point but
the health problems Dolly had at this
young age (arthritis and progressive lung
disease) would be extremely rare in a
middle--aged sheep. Dolly's offspring have
middle
been reported to have normal length
telomeres.
Born: 5 July 1996
Died: 14 February 2003
Did Dolly Aged Too Rapidly?
• Dolly’s Cells were taken from a six year
old sheep and Dolly lived six years.
6+6=12 (the normal life span of a sheep
is 1010-16 years).
Cell suicide
• Telomeres are nubs of protein and nucleic acid
that cap the ends of chromosomes, the
structures
t t
iin cells
ll that
th t bundle
b dl up allll the
th DNA.
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.
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2/19/2009
Theories of Senescence
• Q: What are the implications of Dolly’s
abbreviated lifespan for theories of
senescence?
2