Oliver Bogler writes:
>I agree witht the first point - bacteria, for example, do not age as there
>*must* be an unbroken chain of cells from the beginning of the bacterial
>life to today. The germline of higher organisms can be seen similarly as
>an "immortal" clone. (Immortal is in quotes because there was a heated
>debate in this group about the appropriateness of using that word to talk
>about cells - it is used purely in its narrow biological sense).
I believe a distinction must be made between the immortality of bacterial
colonies and cell lines and the immortality of the _individual_ organism.
Colonies may appear immortal and appear to have a single genotype, but the
actual, single bacterium (if it could be isolated) might be found to die after a
limited number of divisions.
In yeast, careful separation of mother and daughter cells has shown that the
mother cell stops dividing after budding and eventually dies.
seto at mit.edu