Stereoscopic back-scattered electron imaging of silver-stained proteins in nucleoli.
By using simultaneously the AgNOR silver staining method, back-scattered electron imaging mode and stereo-tilt in scanning electron microscopy (SEM), it is possible to observe the nucleus through the cell surface, the nucleolus, and the tri-dimensional distribution of the Ag-NOR-associated acidic proteins. In C3H10T1:2 cells and their 7-12-dimethylbenz-alpha-anthracene-treated transformants, the staining demonstrates several intranucleolar silver-staining granules (SSG), surrounded by a weakly staining region. The SSG may represent the fibrillar center (FC) and the weakly staining region, the fibrillar dense component (FD). This component can link several SSG together to form a "rope-like structure". In cells with no visible nucleolus and inactive nucleolar organizer regions (NORs) the silver-staining granules are less numerous, close together and the presumed fibrillar dense components are not visible. The SSG are located more peripherally, and the weakly staining region and the "rope-like structure" are less prominent in control cell nucleoli than in transformed cells with a comparatively high rate of RNA synthesis.
D015127:9,10-Dimethyl-1,2-benzanthracene / Q000494:pharmacology; D002466:Cell Nucleolus / Q000648:ultrastructure*; D002471:Cell Transformation, Neoplastic / Q000473:pathology*; D002478:Cells, Cultured; D009697:Nucleolus Organizer Region / Q000648:ultrastructure*; D012834:Silver
D012834:Silver; D015127:9,10-Dimethyl-1,2-benzanthracene