Ethidium bromide

Sergio sergioal at bbm1.ucm.es
Tue Jul 17 02:50:05 EST 2001



"Michael L. Sullivan" wrote:

> >>
> >> The problem with this strategy is that your EtBr will migrate in the
> >> opposite direction of your DNA during electrophoresis. This will make
> >> that the band with a lower molecular weigth will be less visible.
> >> Soaking the gel in a 1ug/ml EtBr solution for 10 min eradicates that
> >> problem.
> >>
> >> LV
> >
> >We find also that adding EtBr directly to the running buffer as well as
> >the gel eliminates this problem. No soaking, destaining, or other annoying
> >step is necessary. Just add EtBr to the same concentration as in your gel.
> >Background is very minimal in our experience.
> >
> >J. Rinehart
>
> Most of the time I think the EtBr can be omitted from the running buffer
> since most people are so anxious to see their results gels seem to rarely
> get run more than half way.
>
> Even if a gel is run all the way without EtBr in the buffer, although the
> bands are much lighter, the background is extrememly low, so I've found
> that it's still easy to detect bands.
>

Besides the sensitivity, i don't like to have all the electrophoresis tanks full
of EtBr. I was a fervent supporter of EtBr into the gels until i checked the
surrounding area, the power pack and pippetes the for EtBr contamination....
scary results. I don't like the looking of the pre-stained gels either, since
the EtBr runs towards the cathode the upper (or lower, depending how you look at
the gel) part of the gel has a high background and the opposite part is almost
destained. On the other hand, staining and destaining don't take (usually) more
than 10 minutes. For urgent gels we still keep a contaminated electrophoresis
tank in a special area of the lab.

Sergio







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