petite mutants

Tomas Drgon tomasd at bdg10.niddk.nih.gov
Thu Oct 5 11:11:58 EST 1995


In article <44feln$f2m at newsbf02.news.aol.com>, cmsaville at aol.com
(CMSaville) wrote:

> Hello,
> 
>    A colleague of mine is trying to use an ade2 reversion assay to
> demonstrate UV mutagenesis in an undergraduate lab course.  I have a
> couple of questions.  First, what is the best media to use to get the best
> red color in colonies?  Second, when the ade2 strain is grown on YPD
> plates, most colonies are red, but there are often many small white
> colonies present.  Up to 40-50%.  One suggestion we have received is that
> these are due to petite mutants.  To get around this we have tried to grow
>  them on YPglycerol, but these do not turn red.   
>   Any other suggestions? Is this common?  Is the petite mutant idea a
> reasonable explanation?
> 
> Please respond to ksaville at alpha.albion.edu
> 
> Thanks in advance.
> 
> Ken Saville


Hi Ken.

In my hands, the best medium for ade2 color development was YNB,2%
glucose,+0.12 mg/ml adenine (or evel less, adenine conc. has to be
limiting). The color development is pH dependent, at pH7 the color was
stronger that at pH5. Petites turn red much more slowly, but you should
not get spontaneously more that 5 to 10% of petites in a wildtype. A pain
is, that you get sometimes reversions very easy.

For more info:
Jones EW and Fink GR (1982) in: The Molecular Biology of the Yeast
Saccharomyces cerevisiae, Metabolism and Gene Expression (Strathern EW et
al eds.) Cold Spring Harbor Laboratory, pages 181-299.

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