Sizing microsatellites. Is there a true answer?

carlos carlos at
Mon Jun 27 16:53:56 EST 1994

We have been screening populations of insects for microsatellite
variation.  We amplify individual microsatellites and size them by
running them in a denaturing gel (standard acrylamide urea stuff) along
a sequence of m13 provided by USB with the sequenase kit.  I have
amplified the same microsatellite site from the saame group of
individuals at least three times and run them in three different gels
and have come up with different sizes for the same fragment (!?)  USB
swears that there are no differences in the m13 batches and that the
-40 primer is the same.  They suggest that my samples may be folding or
compressing due to gel to gel variations.  However, other
microsatellites run in the same gel seem to show up consistently at the
right place.  Any suggestions and or explanations?


Carlos R. Solis
carlos at

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