In article <3no34u$hk9 at mserv1.dl.ac.uk>, <W.G.VAN.DOORN at ATO.AGRO.NL> wrote:
> *Would it not be better to use neutral terms for the stages in cell cultures
> *like a) dividing, b) quiescent, c) nondividing, and d) perpetually dividing,
> *or any other set of terms that just describes the facts.
>Yes indeed it would be better, and in fact it is so. Here they are:
dividing: the cell cycles to produce daughter cells
quiescent: the cell is not currently dividing, but has the capacity to do
so when stimulated with appropriate growth factors. (G0 of cell cycle)
non-dividing: same as quiescent - not used often
senescent: the cell is in a normally irreversible form of G0 where it will
not divide no matter what stimulants are applied. It is however viable,
and can remain so for some time.
apoptotic: the cell is undergoing programmed cell death, i.e. has stopped
dividing *and* is breaking apart.
necrotic: the cell is dying due to extrinsice factors
mortal: the cell can divide for a limit period of time (with periods of
quiescence possible) at the end of which it spontaneously enters
senescence and/or apoptosis.
immortal: the cell never undergoes senescence or apoptosis spontaneously
(note: it could be quiescent)
transformed: in addition to being immortal the cell now exhibits other
hallmarks of tumor cells.
These are the definitions of the common terms used by people working in
the field. It has to be understood that some of the same words are used by
laypeople to mean different things. This is common in English, I'm afraid.
I hope I have helped in clarifying this difficult area.
As to the other point in the previous post: bacteria, as individual cells
may only live a few days/hours/minutes, but what happens at the end? They
divide. Of course I'm assuming that the cells are maintained in ideal
circumstances - we are discussing the potential of cells to divide, not
what happens to them if you leave them to exhaust the nutrients on your
petri dish in the fridge. If you restreaked a colony on a agar plate every
day, I bet you the bugs would outlive you. The same is true of immortal
cells - they'll keep growing if maintained in optimum conditions.
Oliver
--
Oliver Bogler
obogler at ucsd.edu
