Electrophoresis shear thinning

At fixed polymer concentration, p/fio decreases with increasing matrix molecular weight. Rodbard and Chrambach found that p is not independent of M, consistent with many other results on probe electrophoresis and sedimentation. Nonlinear (in E) mobility behavior was observed, namely the probe mobility increased at larger applied fields. The nonlinearity was more pronounced at larger polymer concentrations. The dependence of p upon E could be said to be shear thinning, but if so the relevant shear rate (for example, involving a thin layer around each probe) must be quite large, because direct measurement at lower shear rates found no dependence of the macroscopic on /c. 

Add 1 X TBE buffer to the electrode chambers on both sides of the gel until it is approximately 1 -2 mm below the top of the gel. Do not cover the gel with buffer at any time. Run the gel at 70 mA for 2.5 min, then at 60 mA, usually for 15—20 min (higher amperages may shear the DNA or adversely affect its detectability). The electrophoresis of the DNA should be observed carefully. Ideally, the DNA enters the gel in the first 5 min and moves as a clear, unified, thin wave that should be visible without UV light. Once the wave has moved 1 -2 mm into the gel, turn off the power, remove the leads, and remove most of the IX TBE from the electrode chambers. Dispose of the now DNA-firee solutions in each pocket and rinse the pockets with sterile distilled water. 

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