Uneven band migration on agarose gel - (Sep/16/2007 )

On two occasions, I had DNA ladders which were loaded on each end of a 1x TAE agarose gel showing different rates of migration.
What factor(S) could be causing the apparently different voltages experienced across the gel? Uneven thickness of gel (gels were casted on benchtop)? The buffers for making the gel and tank were from the same batch.

Thanks in advance for replies....

j

Check the wires that run inside the tank, one may be snapped making it shorter, I have seen this cause gels to run unevenly before...

If you're sure your gel was homogenous, like draddoga said, the problem may be the wires. Sometimes it happens when someone cleans the tank that one of the wires gets slightly bended or so. Make sure they're perfectly aligned.

Was your gel fresh? Sometimes when they're stored in buffer for some days the migration of bands gets distorted.
And of course, the dirtier your buffer is, the more it affects the migration...

How much buffer you have over the top of the gel can also affect the migration rate. Also the other big cause is where on the gel the sample are loaded - samples loaded on the side often run differently than those in the middle.

Cheers

Daniel