Selective killing of dividing yeast

Elliot Gingold el at gingold.demon.co.uk
Sat Jul 8 16:17:15 EST 1995


In article <3tbgn4$scp at mserv1.dl.ac.uk>,
TOMASKA at fns.uniba.sk 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
method.

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
effect.

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






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