Re: SYTO red and HOECHST or DAPI

From: Stefan Andreatta (stefan.andreatta@uibk.ac.at)
Date: Fri Jun 08 2001 - 04:07:45 EST


We would also be intersted in measuring DNA and RNA at the same time -
albeit in bacteria. As no specific RNA dyes are available, my idea was
using DAPI and Syto 13 and estimate the relative amounts of RNA and DNA
from a 2D-plot (not quantitatively!). My colleague did some measurements
with an E.coli culture last week to test, whether there is a competition
between the two dyes, which were added in varying concentrations.
However, there were only slight changes in fluorescence, indicating that
both dyes bind more or less independently to the DNA, which seems
reasonable regarding their different binding mechanisms.

Our data is not really conclusive yet and we plan further experiments to
test the feasability of our approach. The key question for us is,
whether we can find different proportions of DAPI/Syto (i.e.
DNA/(DNA+RNA)) in mixed bacterial assemblages. Maybe we will be wiser in
a month or so.

Best Regards
Stefan

-------------------------------------------------
Stefan Andreatta
Institute of Zoology and Limnology
University of Innsbruck, Austria
phone: ++43-512-507-6122; fax (..)-2930


Elena Soriano wrote:
>
> My intention is to use SYTO red for RNA specific staining like I use
> Pyronine- Y. Does anyone knows if this possible?
>
> When I stain the DNA with Hoechst or DAPI (selective for DNA), the
> Pyronine-Y finds no place in these molecules, and therefore binds only to
> the RNA, wich is then the only nucleic acid that has free binding points.
>
> -> Could I block the DNA with Hoechst or DAPI and then stain with SYTO red
> to detect the RNA?
>
> Would SYTO red still find free binding points when the DNA is allready
> stained with one of these DNA selective fluorochromes?
>
> Thanks for your attention!
>
> Elena.
>
> -----------------------------------------
> Elena Soriano
> c/o Institut für Angewandte Mikrobiologie
>     Univ.f.Bodenkultur Wien
>
> Tel: +43 1 36006 6241
> Fax: +43 1 36 97 615
> http://www.boku.ac.at/iam



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