DNA staining

From: Ann Atzberger (Ann.Atzberger@EMBL-Heidelberg.de)
Date: Mon Dec 18 2000 - 09:34:26 EST


Hallo everybody,

The users here are encouraged to follow protocols from "Current Protocols
in Cytometry" whenever possible. Recently we've started doing a lot of DNA
staining and have noticed variation in fluorescence between similar samples
when utilising PI. On scrutinising the given protocol in CPC, it says you
can have a cell suspension of 1 million to 10 million cells for PI. For
Dapi it says 100 thousand to 1 million, and for Hoechst a suspension of 1
million. Somewhere in the past I learnt that you use a constant number of
cells depending on the protocol.

I take it it should mean you can stain up to a certain concentration of
cells but omits to explain that the cell number per sample should not vary.

However, if you can vary the cell concentration to such an extent surely
the A-T bases are no longer saturated and will give sub-optimal staining.
Oui???

In the case of Hoeschst where the users go by the 1 million cell conc. we
do not see the peaks shifting up and down between samples.

Regards
Ann

Merry Xmas



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