Glowing Blue DNA Gels

Paul Haney paul_haney at
Wed Apr 20 12:44:49 EST 1994

In article <2oshhf$2lo at>, forrest at
(Alistair Forrest) wrote:

> Just sounds like you've got too much EtBr in your running buffer. To overcome
> this you could try including the EtBr in your gel (we use 20ul of 10mg/ml in
> a 40ml gel) or you could also try prestaining the gel in a concentrated solutionof EtBr before running. The advantage of this system is that as the EtBr is alsoelectrophoretically mobile and smaller than the DNA, it will run off the end of the gel. The EtBr is then diluted in the running buffer and as such it won't
> matter if the Et Br is recirculated to the front of the gel as by now it is
> so dilute it shouldn't pose any problem.
> Alistair Forrest

Even this concentration (5 ug/ml) is a bit high.  Maniatis et al.  suggests
0.5 ug/ml EtBr...I routinely use 1 ug/ml and get great staining of even
very small concentrations of DNA.  To keep the EtBr concentrations uniform
during a run, I put the same concentration of EtBr in my gel running buffer
as well.  

I would agree with Dr. May about the blue dots on the gel...our
transilluminator occasionally gets junk on it which glows blue when the UV
lamp is on.  Rinsing it off with water or ethanol works pretty well.

Ed Beaty
Ed_Beaty at

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