Hi-
Try starving your cells in conditioned starvation medium from high 
density cells, as it contains CMF, which is necessary for prespore gene 
expression.  For more info, look at the various papers on CMF.
cheers
Richard Gomer

On Mar 20, 2009, at 11:34 AM, Michael Myre wrote:

> I too would find this informative as I am currently characterizing 
> mutants that make defective spores and I have seen the same 
> sporulation ratio effects mentioned when using 2 through 20 mM 
> 8-Br-cAMP on cell densities of 1 x 10^4 cells/cm2 to 1 x 10^5 
> cells/cm2.
>
> Thanks greatly,
>
> Mike
>
> Liao, Xin-hua (NIH/NIDDK) [F] wrote:
> > Dear Dicty Colleagues,
> >
> > Recently I am tying sporulation assay with 8-Br-cAMP, and looking 
> for a
> > condition that can give rise to more than 90% of spore 
> differentiation.
> > I found high density of cells could greatly increase the sporulation
> > ratio. Cell-cell contact seems favor spore differentiation a lot.
> > However, higher density of cells sometimes also leads to cell
> > aggregation.
> >
> >
> >
> > Does anyone have idea about avoiding cell aggregation but not 
> disturbing
> > spore differentiation? Any idea about increasing spore 
> differentiation
> > ratio will be also appreciated.
> >
> > Thanks, Xin-Hua Liao
> >
> >
> >
> >
> >