Bismuth hematoxylin staining of nucleic acids

Abstract

Hematoxylin is readily oxidized to the blue pigment hematein. Hematein can complex with a wide variety of metal salts or mordants to form mordant dyes. These dyes stain various components of animal tissues. The component stained depends on the metal in the mordant dye.Alum hematoxylin uses trivalent aluminum ion as a mordant. At extreme dilution, requiring long staining times, alum hematoxylin is a specific stain for nucleic acids. As usually used, alum hematoxylin stains nucleoproteins, staining them nearly as well after the removal of the nucleic acids as before.Bismuth shows a high affinity for nucleic acids. Although all common bismuth salts are insoluble in water, sodium bismuthate reacts with an aqueous solution of hematoxylin to produce hematein and trivalent bismuth ions. The bismuth ions complex with the hematein to form a water-soluble “bismuth hematoxylin.” HEPES (N-[2-hydroxyethyl]piperazine- N'-2-ethanesulfonic acid), 8 mg/ml of solution, greatly increases the amount of bismuth hematoxylin formed. Glycerol, 1/8 v/v, improves the stability of the complex.