title: Visualization of nucleolar organizer regions im mammalian chromosomes using silver staining.
abstract: A simple ammoniacal silver staining procedure, designated Ag-AS, differentially stains the chromosomal locations of ribosomal DNA in certain mammalian species. This was critically demonstrated by Ag-AS staining of the nucleolus organizer regions in karyotypes of the same species and cell lines used for locating the ribosomal cistrons by DNA/RNA in situ hybridization. With Ag-AS, silver stained NORs (Ag-NORs) are visualized as black spherical bodies on yellow-brown chromosome arms. Ag-NORs were visualized throughout mitosis at the secondary constrictions in the rat kangaroo, Seba's fruit bat, Indian muntjac, and Rhesus monkey. The Chinese hamster and cattle have telomeric Ag-NORs, the mouse subcentromeric Ag-NORs, and the field vole Ag-NORs as minute short arms or choromosomal satellites. Ag-NORs occur at both secondary constrictions and at telomeres in the cotton rat. Variability in Ag-NOR pattern included differences in the number of Ag-NORs per cell within a cell population, size of Ag-NORs among chromosomes of a complement, and presence of Ag-NOR on particular chromosomes in two cell lines of the Chinese hamster. The available cytochemical data suggest that the Ag-AS reaction stains chromosomal proteins at the NOR rather than the rDNA itself.
mesh_terms: D000818:Animals; D003411:Arvicolinae; D002685:Chiroptera; D002874:Chromosome Mapping; D002875:Chromosomes / Q000378:metabolism / Q000648:ultrastructure*; D006224:Cricetinae; D003670:Deer; D005260:Female; D005796:Genes; D000882:Haplorhini; D007621:Karyotyping; D008253:Macaca mulatta; D007614:Macropodidae; D008297:Male; D051379:Mice; D008938:Mitosis; D009698:Nucleoproteins / Q000032:analysis; D012335:RNA, Ribosomal / Q000096:biosynthesis; D051381:Rats; D012834:Silver; D013194:Staining and Labeling
chemical_list: D009698:Nucleoproteins; D012335:RNA, Ribosomal; D012834:Silver