Practical Manual of Cytogenetics, Molecular Biology and Biotechnology

This stain contains fuchsin or magenta I, a decolorized dye which has a strong affinity for DNA, producing a red color in its presence. Also called "rosaniline," is an aniline dye which consists of three aniline rings, one meta-methylated, para-at-tached to a central carbon. Its positively charged nitrogen is at-tracted to and stains the negatively charged PO4 groups in the DNA backbone. It is nearly colorless until it reacts with the PO4 which turns it red.