Relationship between the Ag-NOR proteins and ribosomal chromatin in situ during drug-induced RNA synthesis inhibition.
In human TG tumor cells, the role of silver-NOR proteins was investigated by examining their relationship with the chromatin structure during inhibition of RNA synthesis by actionomycin-D treatment. This induced segregation of the nucleoli into four distinct zones and weakened the silver reaction. The fibrillar components were found to constitute the site of silver-stained proteins segregation. Feulgen-like osmium-ammine staining revealed that the DNA disappeared from the segregated nucleoli except for a network of nonnucleosomal filaments. When Ag-NOR protein detection was combined with chromatin visualization, we found constant overlapping of the silver reaction sites with the nonnucleosomal DNA filaments. Our results indicate that certain Ag-NOR proteins are not directly linked to active rRNA synthesis, but might rather affect the structure of ribosomal genes.
D002460:Cell Line; D002843:Chromatin / Q000032:analysis*; D003609:Dactinomycin / Q000494:pharmacology; D003864:Depression, Chemical; D006801:Humans; D009687:Nuclear Proteins; D009697:Nucleolus Organizer Region / Q000032:analysis* / Q000648:ultrastructure; D000090243:Nucleophosmin; D012335:RNA, Ribosomal / Q000096:biosynthesis*; D012261:Ribonucleoproteins / Q000032:analysis*; D012834:Silver; D013194:Staining and Labeling
D002843:Chromatin; D009687:Nuclear Proteins; D012335:RNA, Ribosomal; D012261:Ribonucleoproteins; D000090243:Nucleophosmin; D003609:Dactinomycin; D012834:Silver