Schlierens or Swirls in PolyAcrylamide Gradient Gel

Tony Nugent tnugent at
Wed Apr 5 16:00:07 EST 2006

I am wondering if anyone else has these artifacts and if they can help
me understand them.
We cast gels by pumping a lo and hi percentage acrylamide into the
bottom of a casting chamber 
and then up betweent he glass plates over about 15 minutes.
This is followed by about 5 minutes of a high density Sucrose solution 
to fill the dead volume at the bottom during polymerisation.
>From time to time we get schlierens or wavy lines, typically
horizontally in various regions of the gel.
These lines are almost ghost like, the Lab operator sees them and then
the scientists and engineers peer at the gels until they see them
They often require quite a bit of manipulation of the cassette against
natural light to see. 
We have run some of these gels and often see no problems, but
occassionally we have see lateral streaks in a gel (we do vertical
electrophoresis), somewhat like these lines. 
These streaks may be connected and the fact we do not see them often is,
1 the Lab operator discards gels if they have these artifacts, or if not
caught they are not near any bands so we see no problem(luck?).
For others who cast gels, do you see these faint schlierens, and have
you any experience with them.
Tony Nugent

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