FOA problems-Help

John Stebbins stebbin1 at
Sat Feb 8 15:32:30 EST 1997

I recently knocked out a gene using a hisG-URA3-hisG cassette in 4 versions
of a given yeast strain (one wild type PSY316, and three deletion mutants
thereof).  I have been attempting to recover the the auxotrophic for ura3
version of all of these and have only been successful with the wild type
PSY316.  I have given these ample time to recombine out by growing them in
YPD.  I then move them to YPD FOA plates and get colonies that later prove
to still have the URA3 gene!?!
I have been told that minimal media with FOA might work better and am in the
process of trying this.  Does anyone have any suggestions on what might be
the problem and more important any solutions to it?

Thanks...John Stebbins

                John Stebbins
                stebbin1 at
                Michigan State University
                Dept. of Biochemistry
                (517) 432-3668

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