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Fig. 3. Colchicine-treated meristematic metaphase cells of rye. (a) Simultaneous
visualization of chromatin (DAPI staining in blue) and of the rDNA
hybridization sites (red) reveals the presence of two NORs exhibiting a
centromere-proximal block of rDNA followed by a ribosomal chromatin filament
towards the satellite (brackets). Note the clear length differences between
the decondensed regions of the two homologous rDNA loci. (b) The simultaneous
visualization of the in situ hybridization and the silver staining signals
shows that the Ag-positive rDNA fraction is found only coincident with the
distended ribosomal chromatin revealed by FISH (compare with a). Bar, 5
µm.