Gel smiling problem

pradeep at pradeep at
Sun Aug 31 08:10:26 EST 1997

Dear netters:

I am repeatedly encountering a problem which I heard is known
as "smiling" of PAGE (denat) gels run at high temp (50-60 C).
Outer lanes in the gel show a distinct curvature toward the outer
edges. So far as I can remember, this is usually caused by 
non-uniform heat distribution/dissipation. However, I
could not find any discussion on this phenomenon in the Current

Short Protocols on Molecular Biology (Condensed version of the 
"Red book", we do not have the full book here) or in Maniatis.
The book "Gel Electrophoresis of Nucleic Acids" (IRL) 
is also not much help, it mentions this effect but does not
discuss. I would really appreciate references/papers on this
effect. Specifically, I am also interested in knowing

1. Can "smiling" be caused by any factor other than heat?
2. Is it possible that acrylamide/bis contained impurities
 (if they are not very good grade) leading to unequal distribution
 of heat or distortions in the electric field ?
3. Is it possible that glass plates lose uniformity after repeated
 use and may contribute to this effect ?

What are the experiences of users who have encountered 
smiling(!) gels ? How have they countered this problem ?

Pradeep at

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