Hi Folks,

    Thanks for the flurry of info about DNA/RNA
staining.  I've summarized some of this info below
in case anyone else has needs related to ours.
    What I neglected to mention is that we are
trying to count nuclei inside of living mouse
embryos.  That's why we're searching for a
non-invasive, membrane crossing, nuclear-selective dye.

So I have a few more specific questions:

(1).  Lasers can excite dyes very far from the absorbance
max.  Has anyone ever tried looking at DAPI with the
488 line of the argon-krypton?

(2) Is the Hoechst dye longer or shorter then DAPI?
(i.e. might we try nipping it with the 488?)

(3) Several folks suggested visible wavelength dyes
(see list below).  Do any of these cross membranes?
Yield bright nuclei?


My apologies for the vagueness of my first query.
And Thanks Again!

Don



Summary of recent listserv messages:


Possible Dyes for live TISSUE, visible wavelength,
selective NUCLEAR staining:

DAPI - if we can nip it with  the 488 line...
Green Syto-stains nuclei.  But does it cross membranes?
7 aminoactinomycin.  But does it cross membranes?
microinjected Alexa-UTPs
Chromomycin A3 is staining DNA selectively.excit: 488
    - crosses membranes?
TO-PRO 3 (Molecular Probes) dsDNA >>RNA and ssDNA
   - crosses membranes?

Dyes that are won't stain living cells:
PI, Yoyo- Require RNAse step
Toto3- seems to require RNAse step

Dyes that I think will not give nice nuclei:
Acridine Orange, LDS 751

Other dyes to consider:
Hoechst will stain live cells, but I think is UV.

Nuclear Staining Reference:
Acta Histochem. Cytochem. Vol 30 #3 309-314 (1997)
[don't have this journal in my library; still
pursuing a copy]

Thanks to everyone that contributed to this list.
Don O'Malley
Northeastern University