Gel smiling problem

Rob Kirkpatrick kirkpat at
Wed Sep 10 19:28:12 EST 1997

In article <340E18C7.7C8E at>, fordb at wrote:
> > 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 ?
> > 

In our lab, we overcome some of the smiling problem by loading extra
samples on either side of the lanes, with no spaces between any wells.  It
seems that the outer lanes are more prone to smiling regardless of
position in the gel so you load the extra lanes as a "sacrifice" to
prevent smiling in the lanes you really care about.  I have no idea why
this works.



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