Dead Cell Marker on 633 nm

Douglas B. Kell dbk at
Fri Nov 8 20:33:51 EST 1996

> I have used
> TO-PRO-3 as  live dead discriminator with red excitation.  Note that
> the -3 is important, Molecular Probes also sells TO-PRO-1!
> For TP3, saturating concentration is 2-4 uM.  

I'll say.....esp. in view of what follows. How much DNA stain do
people want to whack about, on the reasonable asumption that that
which binds to DNA may not be frightfully good for it?

>I routinely use 10-40
> nM for live vs dead discrimination.  Since this will require
> creating a diluted stock, do the dilution in DMSO or else do not
> store an aqueous (PBS) dilution in polystyrene - the dye
> concentration will decrease over time possibly due to loss to the
> tube wall.  Polypropylene is better.

Out of interest, what is here the  'gold standard'? We in Aber are
beginning to have suspicions that supposedly pure(ish)  TO-PRO[3],
or likely a metabolite / degradation product thereof, penetrates (and
ergo stains) ""live"" [i.e. not all that knackered] cells (bugs). 

What say you, and netters to whom this is copied?

(Prof) Douglas B. Kell
Edward Llwyd Building, 
Institute of Biological Sciences
University of Wales,
Aberystwyth SY23 3DA, UK
Tel +44 1970 622334
Fax +44 1970 622354
dbk at

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