viability assays

[Martin Hughes Bioc]

>In article <26lcir$n6j at bigboote.WPI.EDU> eeyore at wpi.WPI.EDU ( eeYORE ) writes:
>>Subject: viability assays
>

[about wanting a viability assay for roots

>>I have tried FDA (fluorescein diacetate) stain, but this is not quantitative
>>or reliable for plant tissue.  Anyone have any ideas or experience?
>>                                                                        Melissa

I would also like to add a request.  I have been using FDA to assay
for viability in protoplasts, which is a "normal" recomended method.
I am trying (as a control) to kill off protoplasts.  Unfortunately,
follwing a "death" treatment (30 min in 0.1% NaAzide, or 0.3% KCyanide)-
which I imagine should be pretty fatal to the cells, the FDA stain
still shows positive (this is also the case with even higher toxin
levels).  Any suggestions for a more sensitive method of viability 
staining would be appreciated.
Thanks
-- 
Martin J. G. Hughes
Department of Biochemistry, University of Cambridge, Cambridge, UK.
Email: mjgh at mbfs.bio.cam.ac.uk