Comparison of ethidium bromide and 4'6-diamidino-2-phenylindole as quantitative fluorescent stains for DNA in agarose...

Two methods of quantitative, fluorescent detection of DNA bands in agarose gels separated by electrophoresis were evaluated for sensitivity and linearity of response. Comparisons of ethidium bromide staining with a method using 4',6-diamidino-2-phenylindole (DAPI) developed in this work showed that DAPI is several times more sensitive than ethidium bromide in conditions of comparable background fluorescence. Optimum fluorescent staining and detection conditions for DNA bands in agarose gels using DAPI are described, and advantages of this method over other fluorescent detection methods are discussed.