Can someone refer me to data on the migration of circular molecules
in agarose gels with and without the gels being prestained with
ethidium bromide? We see a series of bands of slightly differing
size when a 2 kb insert is ligated to itself in gels stained
after electrophoresis, but a predominately stained band
if we place similarly treated samples in empty lanes of gels which
had previously been stained before (& then after electrophoresis).
Is this an expected anomaly?