The use of DAPI as a replacement for ethidium bromide in forensic DNA analysis.

Ethidium bromide is used extensively for the visualization of DNA in forensic applications. This is usually accomplished by the addition of dye to the gel and buffer before electrophoresis or by staining the gel after the run. In both procedures considerable ethidium bromide containing buffer is generated that must be decontaminated. We demonstrate that another fluorescent DNA binding dye, 4',6-diamidino-2-phenylindole dihydrochloride (DAPI), can be used in place of ethidium bromide for yield and restriction gels, and to stain the visual marker of analytical gels. A low concentration of DAPI is added directly to the DNA. Most of the stain is immediately bound to the DNA and remains bound during electrophoresis.