In article <mit.edu-2911951015050001 at cancer-ctr-mac-7.mit.edu>, mit.edu
> I am utilizing the Tet inducible (repressable) system for conditional gene
> expression developed by Gossen and Bujard. I've found that lines which
> initially showed inducible expression of the desired gene eventually cease
> to induce these genes after several passages. Anyone else seen these?
> What causes this? How do you prevent it? Thanks
They feed cows loads of antibiotics and I have heard that the calf serum
used in tissue culture may contain tetracycline or tet derivatives which
can therefore cause repression (or induction) of expression in the absence
of added tet. You may want to try another batch of serum. I am starting to
use this gene expression system and I will be watching out for possible
bad batches of serum.
voellerj at gunet.georgetown.edu
Lombardi Cancer Center, Georgetown University
Washington DC, USA