CASTING METAPHOR AGAROSE GELS

[Perry J. Bushong]

I have had a difficult time trying to get consistent 
results running microsatellites on 4% Metaphor 
agarose gel.  The gels always run crooked.  One side 
of my 34 lane, 3mm gel always runs faster than the 
other.  Yet there is no pattern to it; sometimes the 
left side runs faster, sometimes the right, and 
sometimes the middle.  I thought the problem was due 
to an unlevel casting tray, but I always use a 
leveler to make sure.  I then thought maybe my 
agarose was hardening before it spread out so I tried 
submerging the Bio-rad casting tray under warm water 
(about 65degC) the same temp as the agarose being 
poured. I even tried using a 3% gel but got the same 
results. I have never had so much trouble casting a 
gel before. 
Does anyone out know any tricks to casting Metaphor 
gels consistently?  Thanks.
Perry