Selective killing of dividing yeast

Preston Garrison garrisonp at UTHSCSA.EDU
Tue Jul 11 16:49:20 EST 1995

Elliot Gingold wrote:

>In article <3tbgn4$scp at>,
>TOMASKA at wrote:
>>Can somebody suggest a method of selective killing of groowing as
>>opossed too non-dividing yeast cells?
>At the Lisbon yeast meeting last month, there was a poster that carried an
>interesting variation on the standard methods in use for this problem.
>Unfortunately, I did not note down which poster at the time, and I now
>cannot remember, or trace it in the abstract book! So if the authors read
>this, or anyone else who remembers the poster (or uses a similar method)
>does, I would be grateful if you could follow this up with details of the
>The method was based on the use of ethidium bromide in media which does not
>support growth of the required mutant type. Ethidium bromide converts close
>to 100% of growing cells into petites. So growing cells are not killed, but
>can subsequently be selected against by placing the culture in non
>fermentable media (eg glycerol-ethanol based). The petites will not grow,
>so only those cells which hadn't grown in the previous media will now grow.
>In practice, the fact that the non-required cells are not actually killed
>should be an advantage. The main problem with penicillin/nystatin type
>methods is that the killed cells leak nutrients into the media which can
>enable previously non-growing mutants to commence growth and hence
>themselves be killed. Converting cells to petites should not have this side
>Of course, this is not to say it won't have other problems. How close to
>100% conversion do you get? Will the non-growing cells really not be
>affected etc. But it sounds good and seems well worth a try. So if the
>authors could please get into contact?
>About 20 years ago I spent a little time unsuccessfully trying to use the
>nystatin method. This followed a period when I had made much use of
>ethidium bromide to generate petites! So, I keep asking myself, why didn't
>I think of that.....?
>Elliot Gingold
>South Bank University

An EthBr method is described in McCusker and Haber, Genetics 119: 303-315
1988. They say the method was modified from one provided by D. Perlman.
They claimed they could get 50% of colonies as auxotrophic mutants.

Preston Garrison
garrisonp at
Biochem. Dept.
Univ of Texas Health Sci Ctr
San Antonio, Tx 78284-7760 USA

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