In article <3terl3$hqu at cisunix1.dfci.harvard.edu>
york at mbcrr.dfci.harvard.edu (Ian A. York) writes:
> This may be too broad a question, but what the heck. How stably are
> plasmids maintained in S cervisiae? That is, if you stop selective
> pressure, and assuming that the plasmid isn't expressing something toxic,
> what kind of half-life will it show? Will most of the plasmid be lost
> after 6 hours in culture? 24 hours? A week? Or is it unpredicatable,
> or does it depend on other conditions? I'm specifically thinking of 2
> micron plasmids, but any information would be helpful.
> Ian York (york at mbcrr.harvard.edu)
> Dana-Farber Cancer Institute, 44 Binney St., Boston MA 02115
> Phone (617)-632-3921 Fax (617)-632-2627
The chapter on "Cloning Genes by Complementation in Yeast" in Meth.
Enzymol. (by Mark Rose and James Broach, pp. 195-230, vol. 194)
contains info. on the stability of YEp and YCp plasmids (overnight
growth under non-selective conditions will yield 90-99% YCp containing
cells and 80-95% YEp containing cells). This info. is on pages 199 and
206. We use the vectors of Gietz and Sugino quite a bit, and info. on
thier stability (as well as a ref. to other plasmids) is given in the
article describing these plasmids (Gene 74:527 ). In my
experience, growing cultures to saturation under non-selective
conditions can result in quite a bit of plasmid loss - e.g. growth of a
diploid with a LEU2 marked CEN plasmid to saturation results in less
than half of the colonies that grow on YPD being Leu+. I haven't
looked at YEp plasmids in the same way.
Also, larger CEN plasmids are more stable - this is stated in the
Gietz&Sugino ref. (and elsewhere, but I can't remember off the top of
my head) and I observed it in the expts. I described above.
Hope this was of help...sorry I didn't have more info directly relevent
Univ. of New Mexico
Dept. of Biology
(ebraun at mail.unm.edu)