Movement of fluorescence pattern after photobleaching: an accelerated procedure for DNA electrophoretic mobility...

A new approach which is compatible with many of the existing procedures for the analysis of DNA species in gel electrophoresis is being demonstrated. It takes advantage of fluorescence photobleaching in order to create a sharp boundary between the stained and the (partially) photobleached DNA. By arbitrarily creating a stained DNA band of narrower width, the sensitivity to detect (averaged) DNA band movements has been increased. This feature permits measurements of time-dependent electrophoretic mobility over very short time periods. The approach can be used to shorten the running time of gel electrophoresis experiment and to increase the resolution because of the sharper boundary and narrower band width. With faster running time, diffusion of both DNA and dye in the gel also becomes less serious. Movement of fluorescence pattern after photobleaching also permits measurements of localized motions when the gel pores are small in comparison with DNA sizes. Experiments demonstrating some aspects of the proposed technique, as well as the anticipated limitations, are presented and discussed.