A comparison of methods for blocking staining of nucleic acids.

Using rat spinal cord as test material 4 methods for blocking staining of nucleic acids with simple basic dyes have been compared. Two of these methods--a perchloric acid procedure for tissue blocks and a Ba(OH)2 technic for sections--block staining of RNA. The other two-immersion of sections in solutions of dichlorodiammine Pt II or in 10% zirconyl chloride-blocked staining of both RNA and DNA. None of these methods hydrolyze DNA sufficiently to produce a positive Feulgen and no loss of protein could be demonstrated. With the three metal containing procedures some metal could be demonstrated in the sections. This deposition was primarily in nucleic acid containing structures and was greatest and most widespread with the zirconyl chloride. The latter method altered the color of all hematoxylin technics to a deep red. The separation of nuclear stains on the basis of their bonding characteristics into three groups (Lillie et al. 1976) was confirmed.