HISTOCHEMICAL STUDIES ON THE INTRACELLULAR LOCALIZATION OF ACID DEOXYRIBONUCLEASE

Abstract

The effects of various methods of fixation and of different incubation media on staining patterns given by acid deoxyribonuclease (DN-ase II) activity in rat and mouse tissues were studied. It is concluded that the best results are obtained by use of frozen sections after fixation of tissue in cold formol-calcium. The incubation medium we suggest differs from the original one of Aronson et al. (3) in its higher pH (5.9), lower lead concentration (2mM) and the lower concentration of highly polymerized deoxyribonucleic acid. The less polymerized DNA appears more suitable for histochemical purposes. The localization of DN-ase II in both lysosomes and nuclei of different cells is described. Tumor cells are characterized by low enzyme activity. On the basis of differential effects of sulfate ions, two kinds of DN-ase. II, one in the lysosomes and the other in the nuclei, are postulated. The specificity of the reaction and possible roles of DN-ase II in cell metabolism are discussed.