Yeast DNA revisited

From: david.mcfarland@mcmail.vanderbilt.edu
Date: Wed Dec 03 1997 - 13:04:10 EST


I posted a question a while ago about the ins and outs of DNA analysis on yeast. 
I received numerous informative responses.  Thanks.

Information to know:

1)  Yeast have ~300X less chromosomal DNA than mammalian cells.  This explains
what I considered to be a very high voltage needed to place the yeast DNA peak
at a similar spot on the scale vs calf thymocytes.

2)  Yeast have a much larger ratio of mitochondrial to chromosomal DNA.  First
of all, this means that it is more difficult to accurately do cell cycle
analysis.  This is exacerbated by the fact that mitochondrail number can vary
greatly depending on culture conditions.  This becomes more pronounced when
using AT-specific stains like Hoechst and DAPI since the mitochondrial DNA is
about 80% AT.

3)  Permeabilization is very important and must be consistent or you may see
great differences in staining/fluorescence intensity.  (I think this is my main
problem, although I haven't confirmed it yet, especially with yeast that have
been starved and arrested in a G1 cyst-like state, making them very resistant to
environmental changes.) 

4)  Cell number/dye concentration also needs to be consistent to get consistent
staining.

5)  Multinucleation and formation of germ tubes can cause consistency problems
as well as difficulty with doublet discrimination, clumping, turbulence, etc.

Some of this info was taken directly from responses on this forum and also from
the following sources I was referred to:

Lynch ME, KuKuruga MA, Nakeff A, Fidel PL, Sobel JD.  Flow cytometric analysis
of germ tube formation in Candida albicans.  J Med & Vet Mycology 31: 367-376,
1993.

Dien BS, Peterson MS, Srienc F.  Cell-cycle analysis of Saccharomyces
cerevisiae. Methods in Cell Biology 42: 457-475, 1994.

That is all.


David McFarland
Howard Hughes Medical Institute
Flow Cytometry Facility
Vanderbilt University Medical Center  



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