SIMULTANEOUS DIFFERENTIAL STAINING BY A CATIONIC CARBOCYANINE DYE OF NUCLEIC ACIDS, PROTEINS AND CONJUGATED PROTEINS I. PHOSPHOPROTEINS

Abstract

The cationic carbocyanine dye l-ethyl-2-[3-(l-ethylnaphtho[l,2d]thiazolin-2-ylidene)-2-methylpropenyl]-naphtho[1,2d]thiazolium bromide interacts in different ways with several classes of polymeric anions in solution. This results in changes in absorption maxima which differ from the absorption maximum of the dye solution. The multiple interactions with macromolecules were demonstrated in histologic sections. Under appropriate electrolyte, dye and hydrogen ion concentrations, nucleic acids, proteins and conjugated proteins were distinguished from each other by color. The phosphoproteins stained blue, proteins red, nucleic acids purple and mucoproteins and mucopolysaccharides various colors. Further discrimination was obtained by chemical procedures and enzymatic digestions. Secretions in alveolar and ductal lumina in the mammary glands of pregnant mice were shown to stain differentially from the other macromolecules. It is inferred on the basis of enzymatic and chemical procedures that the secretions stained blue because of their phosphoprotein content. Conventional staining procedures did not allow this distinction to be made.