A Differential Stain for Nucleic Acids

An easily used trichrome stain consisting of orange G, methyl green, and toluidine blue is proposed as a method of differentiating desoxyribonucleic acid (DNA) and ribonucleic acid (RNA) in cells. Carnoy's acetic-alcohol is the fixative of choice, though cold acetone is also satisfactory. Photomicrographs taken with ultraviolet and visible light show that the structures containing nucleic acid are exactly those which stain with methyl green and toluidine blue. Studies with nucleases and extraction of nucleic acids with cold and hot perchloric acid further indicate a specificityy of the dyes for DNA and RNA. Present experiments are directed toward using the stain for quantitative estimation of the nucleic acids.