help!! Tetracyclin in serum batch??\

Danny Altschuler dla at
Wed Sep 25 11:18:32 EST 1996

Hey everybody. I'm using the tetracyclin expression system without any
luck so far. The problem is that even my luciferase positive control is
not working. I was wondering if ther problem might be related with
tetracyclin or a tetracyclin-like activity in DMEM or serum that would be
responsible for keeping the system off all the time even in the absence of
exogenous added tetra (induction). Does anyone know anything or have some
experience with that?

Another question. How stable is the tetracyclin? I made a solution 5ug/ul
in 50% ethanol and I keep it at -20C. But after 2-3 rounds of freezing and
thawing I can see some yellow precipitate. Is it normal? Is there any
other way of keeping the stock?\


Please e-mail me to
altschul at

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