Glowing BLUE DNA Gels

Paul N Hengen pnh at
Wed Sep 21 16:49:01 EST 1994

...Just when you thought it was safe to enter the darkroom

: Not having a glove in reach I adjusted the position of a gel with my bare
: hand.  After looking at the gel on UV, I saw that there was a bright blue spot
: at every point I had touched the gel.  That'll teach me to use gloves!
: It was kinda cool looking, 'though, and didn't show up on the film

| Sorry to revive an old tread, but I've just noticed these blue spots
| for the first time (just moved to a new lab) What causes them?

Regarding the on-again off-again thread about glowing blue agarose gels,
I've been following the subject of "Glowing Blue DNA Gels" for sometime and
am looking for ideas or discussion to include in a future edition of the
`Methods and Reagents' column published in TIBS.

Here's your chance to share your experiences with the world.  I've collected
the posted articles since the spring of this year. Some people think that the
source of the glowing BLUE is fluorescent additives or whiteners within laundry
detergents that may be transferred onto your hands if you wipe them on your
clothes or perhaps someone else's clothes.  Gee... I wonder who would be
making hand-to-wherever physical contact in the darkroom ;-)

Okay then, here are the people who were caught "blue"-handed...

From: skralyf at (Frank Anthony Skraly)
Date: 15 Apr 1994 23:37:04 GMT

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.
From: e_hugo at (Eric R. Hugo)
Date: Thu, 21 Apr 1994 10:18:39 GMT

I tend to feel that the glowing blue fluorescence that is sometimes seen 
is more likely an artifact of contamination rather than too much EB.  
Personally, I think it might be due to all of the fluorescent brighteners used 
in everything from laundry detergent to toothpaste.  I've noticed that if I 
reposition a gel without a glove on (I know--Bad scientist <whap whap on the 
wrist>;-) ) I often see blue glowing fingerprints on the edge of the gel.  I 
suspect that this is due to brightener contamination being transferred from my 
clothes.  Personally, I could do without all the additives but I guess I'm not 
quite ready to start doing my laundry by beating my clothes on a rock.
From: rapr at MED.PITT.EDU (Robert Preston)
Date: 29 Apr 1994 07:46:29 -0700

Just paste some of that orange Wratten filter used for photography on your
safety glasses: it blocks the blue fluorescence but lets orange DNA/EtBr
come through.  Possibly you're dealing with a 10X too-high error on the
stock EtBr concentration?

[Note added by pnh in editing: You'll also be quite popular in dance bars too.
...adds new meaning to the phrase "beer-goggles"]
From: djt2 at (Dennis J. Templeton)
Date: 27 Apr 1994 14:18:30 GMT

Can you say autofluorescence? Try pouring a gel without EtBr and it will
also glow bright blue, I bet. We have seen this twice, once while trying to
run a 5% gel (the consistency of a superball) and another time with some
el-cheapo agarose at 1%. I can't recall the brand, name... Gell-O maybe?
Anyway, the odds are good that it results from a contaminant of the agarose
that is not significant at *normal* concentrations of your routinely good
From: aq780 at (Jason Rancourt)
Date: unknown

Another reason for bright blue gels is that you might be overheating your
agarose if you're melting it in the microwave, and its degrading into
bitty autoflorescent monomers. A solution is to nuke it only to the boiling
point and then swirl to dissolve the chunkies. Also, only make agarose in
small batches so that when you get to the agarose dregs it hasn't been
nuked a hundred times.

Any comments, suggestions, and/or crazy ideas are perfectly welcome.
* Paul N. Hengen, Ph.D.                           /--------------------------/*
* National Cancer Institute                       |Internet: pnh at |*
* Laboratory of Mathematical Biology              |   Phone: (301) 846-5581  |*
* Frederick Cancer Research and Development Center|     FAX: (301) 846-5598  |*
* Frederick, Maryland 21702-1201 USA              /--------------------------/*
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