Smiley Face and Purple Haze

Tom Tom
Tue Jul 22 12:17:36 EST 1997


I recently made the switch from the ABI 373 to the ABI 377.  I am
encountering some minor problems that I never saw on the 373.

I typically run in the 4X speed, with a 4% acrylamide gel.  I follow the
recipe given in the manuals (4% acrylamide, 6M urea, 1X TBE, deionize
and degas, use all fresh, high quality reagents).  I let the gel
polymerize for 2 full hours then immediately use it.

The problem I'm having is that the gels are smiling (the characteristic
curved patterns seen sometimes).  The samples in the outside lanes are
migrating much slower than the middle lanes.  The samples themselves
look fine, it's just the smile effect that bothers me.  What are the
causes of this smiling gel problem, and how can I fix it?  Also, I see a
blue haze migrating through the gel way up around the 600 bases area. 
The plates are brand spanking new, so I know it's not build up on the
plates.  What is it?

I'm thinking about switching to Long Ranger.  Can it be used at the 4X
speed?  Is it worth the money?

Any responses would be greatly appreciated.

Tom Nelson
nelson_t at

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