Permeant vital stains for yeasts

[Robert Brambl]

In article <01HAMMGE7PIQ005655 at GW.AGR.CA> BISSETTJ at NCCCOT2.AGR.CA (John  
Bissett) writes:
>    An industry client has an urgent need of a permeant vital
>    stain for Saccharomyces cerevisiae and other yeasts.  Their
>    automated imaging system cannot reliably distinguish yeasts
>    on grid membrane filters from dust and other
>    autofluorescing contaminants.  The stain should not be
>    toxic to yeasts.  A fluorescent brightener should have an
>    emission range other than 415-505 nm, the range of
>    autofluorescence in this application.
>    
>    Has anyone knowledge of vital stains/optical brighteners
>    for this application - or another solution?
>    
>    Please address replies to:   BISSETTJ at NCCCOT2.AGR.CA
>    
>    Thanks
>    
>    John Bissett

An excellent source for a large variety of dyes is a company called  
Molecular Probes (Eugene, Oregon).  A group of dyes you should consider  
are the potentiometric cyanine dyes, some of which report the energization  
of the mitochondrial membrane and which are easily measured with  
fluorescence microscopy. Others may report pH of the cytosol.  One of  
these which works really well for fungi is DiOC7(3), the full name of  
which either Molecular Probes or I can provide, if necessary. If  
autofluorescence remains a problem with your measurements, this could be  
subtracted by treatment of the yeast cell samples with CCCP or DCCD. 

Hope this helps.

R. Brambl