Nucleic acid detection by in situ molecular immunogold labeling procedures

We have recently combined immunogold labeling procedures with molecular bio logy methods to pinpoint the precise locations of nucleic acids in biologic al material at the ultrastructural level. These new immuno-cytological appr oaches involve the incorporation of labeled nucleotides in the nucleic acid s present at the surface of ultrathin sections prior to immunogold labeling . The antibodies used recognize a nucleoside analogue (bromodeoxyuridine) o r a hapten (biotin) employed to label nucleotides. Examples of high-resolut ion detection include DNA or RNA present in different substructures of cell nuclei, and in particular, in adeno-virus-induced intranuclear regions of HeLa cells. In addition to being highly sensitive and specific, these new m ethods offer the possibility of studying the spatial distribution of nuclei c acids in very well preserved, readily recognizable structures.