In article <9312032218.AA05363 at mx.nsi.nasa.gov>,
<FOGEL at biovx1.span.nasa.gov> wrote:
>>I'm using a plasmid with a Gal1-lacZ fusion and finding that there is
>considerable variation in the blue color of the yeast colonies (even though
>I've tried plating with different concentrations of X-Gal). Would anyone
>happen to have another idea as to why this might be happening? Any good
>references on color variation in these fusions would be quite helpful.
I have found that there can be _vast_ differences in expression off the
gal promoter between transformants of the same plasmid. Different strains
may give different results, but this has been my experience. It is also not
unusual to get a number of gal- strains after transformation.
A proffessor that used to be here always went around saying "Transformation
is mutagenic". Apparently that is true.
Unless you have so suspicious activity, just take the colonies that
express your fusion the best ans work with that.
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