EtBr in agarose gels vs. EtBr staining later

Rae Nishi nishir at
Wed Mar 8 17:21:04 EST 1995

We always stain after running the gel.  Here's why:

1. We confine the spread of EtBr to one designated EtBR tub instead of
having EtBR in the glassware used for making the agarose as well as all
over the gel apparatuses.
2. We always get just the right level of staining (not usually over- or
under- stained)
3. The staining is even: EtBr runs in the opposite direction of the DNA
so if you run your gel too long, the lower MW bands may not be stained
4. We can reuse the EtBR solution for staining other gels.
5. It doesn't waste EtBr

BTW: we put 2 ul of a 10 mg/ ml EtBr solution in about 100 mls of water
and our gels (thin 4.5" X 5" gels) stain in 10 min.  You can put EtBr
into RNA loading buffer and it will stay with the RNA; you can't do the
same with DNA cause the EtBr seems to fall off and alters the migration
properties of the DNA.

Rae Nishi
Dept. Cell Biology & Anatomy
Oregon Health Sciences University
Portland Oregon 97201
**that's Orygun, NOT Ora-Gone**

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