EtBr in agarose gels vs. EtBr staining later

Timo Hiltunen bltihi at uta.fi
Tue Feb 28 02:33:37 EST 1995


GORDON BETTS (betts at ORION.ETSU.EDU) wrote:
: It seems to me there are two options for visualizing DNA in agarose gels:
: run a gel with EtBr in the gel or staining the gel after the run.  What are
: the relative merits of the two methods?

I have been using EtBr in the gel and in the running buffer for my PCR gels.
When conc. of EtBr is low, there is no disturbing background, and 
the sensitivity is good. Additionally, small fragments don't start to
diffuse during post-run staining.

The conc. of EtBr in the gel and buffer has been about 6 micrograms / 100 ml.
This is much lower than recommended concentrations.  
Could it be that our technician has had a bad day (again) when preparing
the EtBr solution, or is a conc. this low possible ?

Timo Hiltunen, from the University of Tampere, Finland



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