tet- free serum

Bernard Murray bernard at elsie.nci.nih.gov
Tue Dec 3 15:05:28 EST 1996

In article <581fsa$u1v at netnews.upenn.edu>, rcowherd at mail.med.upenn.edu says...

I am intrigued by the need for tet-free serum which I assume is to be
used to culture cells transfected with tet-controlled vectors.

The antibiotic activity of tetracycline in solution is fairly unstable at
4degC and rapidly disappears at 37degC (certainly in bacterial media)
so is tet stabilised in serum?  I would have thought the opposite was
more likely as tet would bind to serum proteins.  Alternatively,
can "breakdown products" of tet bind to the tet repressor proteins?
Transcriptional changes are reported to start to occur as low as 10 ng/ml
doxycycline (eg. 20 pM) so this would need 200 pM for media containing
10% serum.  Is it possible to add Mg2+/Ca2+  to the medium to chelate
trace amounts of tetracycline?  How about standard heat treatment of
serum - would that be enough to inactivate contaminating tetracycline?

Just wondering if the fuss is justified...


Bernard Murray, Ph.D.
bernard at elsie.nci.nih.gov  (National Cancer Institute, NIH, Bethesda MD, USA)

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