[snystrom]

For some extra context, Dolly was not made using the iPSC approach (reversing differentiation from adult cells). Dolly was cloned using a process called Somatic Cell Nuclear Transfer, where the nucleus of an adult cell is placed inside an embryo, replacing the embryo's nucleus. The embryo then develops using the DNA of the individual that donated the nucleus.

The article kind of alludes poorly to this, but somatic cell nuclear transfer (developed by John Durdon) was a huge milestone in the field that eventually led to Yamanaka's discovery of the pluripotency factors, for which they both won the Nobel prize in 2012.

[Jedd]

That's some excellent context, thank you.

I recall when Dolly was in the news, but only understood the broad strokes of the process. I did scan through that page for 'stem', and found a reference to future research, and noted the replication from an 'adult cell' (which I'd assume analogous to differentiated cell).

I'd guess the transfer process is why she arrived with shorter telomeres at birth?

[snystrom]

> 'adult cell' (which I'd assume analogous to differentiated cell)

That's correct.

> I'd guess the transfer process is why she arrived with shorter telomeres at birth?

Also spot on. The donor somatic cell likely had shortened telomeres, resulting in shorter length in the embryo. It's kind of an interesting research question, because telomere length gets "restored" for germ cells (otherwise every time an organism produced sperm/eggs the telomeres would shorten), and these types of experiments demonstrate that there is a limit to that restorative process.