Glowing Blue DNA Gels

Frank Anthony Skraly skralyf at
Fri Apr 15 18:37:04 EST 1994

What the . . . ?

The last 2 times I ran agarose gels (TAE buffer, stained in dilute ethidium
bromide/water), I put them on the UV box and they glowed 


This made it very difficult to see the orange EtBr/DNA bands. 

The glowing would recede to bright blue spots on the gel after long destaining
periods in water, but would never go away.

Today I ran a well-behaved gel, but it had one blue dot.

Sometimes we use 1X EtBr solutions that have been sitting around for a day or 
two (in the dark), and I wonder if the EtBr turns into something else that 
fluoresces BLUE.  We've always done this, though, and we've never seen the BLUE

Does anyone know what the deal is?  Thanks for reading.

Frank Skraly    University of Wisconsin-Madison

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