EtBr in gels

Teemu Teeri teeri at Operoni.Helsinki.FI
Thu Jun 24 08:54:21 EST 1993

In article <9306182109.AA13410 at> NWALKER at JHUHYG.BITNET (Nigel Walker) writes:

>EtBr in gels not leaking out?!!.Whenever you run a gel containing the EtBr it
>migrates in the opposite direction to the DNA and hence into the buffer chamber

>Mind you..Ive always incorporated EtBr into the gel directly except for gels
>that run a long time....which tend to need abit of extra staining to view small
>quqntites of DNA.

>Nigel Walker

>Johns Hopkins University
>Baltimore. USA

EtBr in gels moves opposite to and binds DNA. This has a couple of 
consequences. When a sample has a lot of nucleic acid in it (including RNA), 
the bands move faster than in a control with less load. This is because the 
material at the front binds EtBr from the gel and the bands that come later 
will not be saturated like the control bands (and move faster). Also, 
overloaded bands smile, since the ends will get more EtBr from the interlane 
region compared to the middle. When you must load much, like in genomic 
Southerns, run the gel without EtBr and the bands will be MUCH prettier.

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