DNA staining without Ethidium

[WHITSITT, MARK STEVEN]

In article <1991Sep19.200745.14131 at menudo.uh.edu>, bchs1b at ELROY.UH.EDU (Michael Benedik) writes...
> 
>	There was a recent thread on how to stain DNA in gels without using
>ethidium bromide. This was especially important to some people designing
>labs for high school students. 
>	I was just browsing through a catalog I received from Midwest
>Scientific where they advertise a product called "Nuclistain" which is a 
>positive stain for the detection of DNA and RNA (double or single strand)
>in agarose or polyacrylamide gels. Detection limit about 50ng. Visible
>in normal light. 
>	The vendor was 	Midwest Scientific, Tel: 1-800-227-9997
>	(except in St.Louis: 225-9997)
> 
>I know nothing about the product or the company but just thought I would
>bring it to your attention if anyone is still interested.


One suitable method for the visualization of nucleic acids is to use methylene 
blue.  Several protocols exist and can be found in the molecular cloning 
handbook by Sambrook et al. as well as a variety of other places.  Basically, 
the gel is soaked in 0.2% methylene blue/ 10mM Tris-acetate (pH 8.3) for 1-2 
hours at 4 degrees C avoiding direct sunlight (ie. the container is covered).
Remove the excess stain by soaking in several changes of distilled water until 
the bands become visible, again avoiding sunlight.  The limit of detection is
around 250ng/1cm band.  This protocol comes from:  Guide to Molecular Staining 
Techniques. Berger SL, and Kimmel AR eds. (Methods of Enzymology vol 152 pp 71.)

This sort of protocol is used in the undergrad Biochem labs where the sheer 
number of students and the toxicity of EtdBr precludes its use.  The labs are 
normally designed such that nucleic acid levels are well above the limit of 
detection and there is usually no problem.  The product you mention may be a use 
of this method and if it is, it is probably overpriced.  Get the reagents 
yourself and make them up accordingly.  If the procedure required a variety of 
reagents, I might suggest getting the kit, but the methylene blue technique is 
VERY simple and works for both polyacrylamide and agarose gels.

Good Luck



Mark S. Whitsitt, N5RJF        Texas A&M University, Dept of Biochemistry
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