dhodges at UCI.EDU dhodges at UCI.EDU
Thu Mar 21 17:46:21 EST 1996

This is in response to the following message from Dale Dickinson regarding
leakiness of the Gal4 system.
Hi all

Our lab has some preliminary results which suggest that UAS-fussion
constructs are leaky.  I have read a lot about this system, and haven't
come across any reports that suggest leakiness.  Does anyone out there
know if this has been observed before?  It is quite important that the
lines I construct do not express until crossed to gal4 lines.

Please feel free to email me directly,
Dale Dickinson
Dept. of Molecular Biology and Genetics,
University of Guelph
Guelph, ON Canada
dadickin at uoguelph.ca

I also have encountered leakiness with the Gal4 system.  I expressed
ribozymes under control of the UAS promoter and used RT/PCR of embryonic
RNA to look at expression.  I found that most lines expressed at some
levels in the absence of Gal4.  Some lines expressed at quite high levels
in the absence of Gal4 and I even had one line in which Gal4 decreased the
expression of the ribozyme compared to the homozygous UAS-Rib line.  I wish
I had been made aware of this problem ahead of time also, as I switched
from heat shock induction to Gal4 to try to eliminate expression under
uninduced conditions.  I'd like to know how many other people have
encountered this as well.


Dianne Hodges
UC Irvine
dhodges at uci.edu

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