[Protein-analysis] How many passages takes to obtain mutants in a cell line?

Nancy E Caceres via proteins%40net.bio.net (by ncaceres At unlnotes.unl.edu)
Thu Dec 14 08:46:40 EST 2006



Hello:

We have a drug resistant cell (murine) line that routinely is grown in
presence of the drug.

When these cell were grown in absence of the drug the phenotype changed to
sensible after 90 passages (we compare levels of accumulation of drug in WT
and resistant cell, the resistant accumulate less).

Can we conclude that there may be single mutation event involved in the
generation of resistance and that after 90 passages in absence of selection
pressure reverted?

Or is it just matter of regulation of expression of genes under that
stress? And that in absence of drug everything goes back to normal levels?
Is 90 passages too long to restore normal levels of expressions and
actually it is a mutation?

How to calculate the mutation frequency and number of passages necessary
for the expression of a mutation?

Thanks for your help!


Nancy


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