A word of caution regarding supravital use of pyronin Y as RNA marker. When used supravitally the fluorescence of pyronin Y (at concentration 1-4 uM) is localized almost exclusively in mitochondria. Under these conditions pyronin Y thus most likely reports mitochondrial transmembrane potential and not cellular RNA content (see the article: http://cancerres.aacrjournals.org/cgi/reprint/46/11/5760 ). It can be therefore substituted by Rhodamine 123 which when used at low concentration (< 1uM) is an excellent marker of mitochondrial potential and also a marker of quiescent cells (see the article: http://www.pubmedcentral.nih.gov/picrender.fcgi?artid=319350&blobtype=pd f ) A combination of DRAQ5 with Rh 123,may therefore accomplish similar resolution of quiescent (stem) cells as supravital staining with Hoechst 33342/pyronin Y Happy Holidays ZD Zbigniew Darzynkiewicz, M.D., Ph.D. Professor of Pathology and Medicine Director, Brander Cancer Research Institute New York Medical College BSB, Room 438 Valhalla, N.Y. 10595 www.darzynkiewicz.com/zbigniew/ -----Original Message----- From: Hou, Stephen [mailto:shou@uci.edu] Sent: Friday, December 21, 2007 8:30 PM To: cyto-inbox Subject: options of vital dyes for Hoechst DNA / Pyronin Y RNA on cytometers without UV laser I have a user who wanted to sort quiescent stem cells based on Hoechst DNA / Pyronin Y RNA analysis. However, our instrument does not have UV laser. Do we have other vital dyes available for measuring DNA/RNA contents? Thanks. Stephen Hou -- End --Received on Mon Dec 24 15:38:00 2007
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