Donald,

to my knowledge, TO-PRO 3 (Molecular Probes) at least stains dsDNA brighter than
RNA and ssDNA. Although the To-Pro 3 is normally observed with a Cy5 type
filterset, the staining is usually  very bright and can often be detected with a
Rodamine filterset, too. With the 633nm laserline on the confocal To-Pro 3 is
our nuclear counter stain of choice without an UV laser.

Tilmann

Tilmann M. Brotz, Ph.D.
Head, Microscopy and Digital Imaging Facility

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+1(301) 435 6402 FAX +1(301) 496 0887

National Institutes of Health
National Cancer Institute
Experimental Immunology Branch
10 Center Dr., MSC 1360
Bldg. 10, Rm 4B36
Bethesda, MD 20892-1360



-----Original Message-----
From: Donald O'Malley [mailto:[log in to unmask]]
Sent: Thursday, March 16, 2000 9:45 AM
To: [log in to unmask]
Subject: Visible DNA Stain


Hi Folks,

      A colleague wants to stain DNA and view it on
a visible-wavelength confocal.  However, she wants
a stain that stains only DNA, not RNA and believes
that all of the visible-wavelength probes that stain
DNA also stain RNA.  [based largely on what's in
the Molecular Probes catalog].
      Does anyone know of a visible stain that stains
DNA either exclusively, or at least more brightly then
RNA?

   Thanks for any suggestions,
Don

[We sadly do not have a UV confocal here]

Donald M. O'Malley, Ph.D.
Department of Biology
414 Mugar Hall
Northeastern University
Boston, MA 02115
[log in to unmask]
www.omalleylab.neu.edu