PAGE of DNA: EtBr?

Ian A. York iayork at
Tue Aug 6 05:44:54 EST 2002

In article <3D4FA56B.1F6E1964 at>,
Philipp Wechner  <philipp.wechner at> wrote:
>Werner schrieb:
>> Can I add Ethidium bromide in the sample before loading to avoid
>> staining of the gel after the electrophoresis run?
>not good idea - EtBr migrates the other way than DNA.
>DNA moves to the Anode, EtBr to the Kathode - you will lose your
>staining if you just add the EtBr to the Sample.

No, you won't.  You may lose a portion of your staining, but I and plenty 
of other people have tried adding EtBr to the sample only and still seen 
acceptable staining after the run.  

However, the quality of staining I saw this way was not nearly as nice as 
either having EtBr in the gel, or staining after the run.  Also, of 
course, if you don't add EtBr to your molecular weight standards they'll 
migrate differently than your samples.  All in all, staining after the run 
(protocol mentioned elsewhere in this thread) is very quick and easy with 
TBE gels and gives very nice clean results, much nicer than EtBr in the 
loading buffer.  It also uses less EtBr if you're running multiple gels.

    Ian York   (iayork at  <>
    "-but as he was a York, I am rather inclined to suppose him a
     very respectable Man." -Jane Austen, The History of England

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