I have found 7-Actinomycin D works great with living tissue but have not
obtained usable labeling with fixed tissues. What is your protocol? What
concentration and time do you use? Any ideas about what might go wrong
other than permeability problems?

the following is from: Tets Minamikawa <[log in to unmask]>

On the other hand, 7-Actinomycin D, available from Sigma or
>Molecular Probes, is a good choice for red staining of the nucleus.
>It binds selectively to GC pair in DNA,
>and you'll get NO specific fluorescence in RNA-containing structures,
>- a lot easier than propidium iodide or any other Feulgen dyes.
>
Larry D. Ackerman
Lily & Yuh Nung Jan Laboratories
Howard Hughes Medical Institute
UCSF, Box 0725, Rm U226
533 Parnassus Ave.
San Francisco, CA 94143

(415) 476-8751  FAX (415) 476-5774
[log in to unmask]