Fig. 7. The heterochromatic transgene Locus A containing a multicopy HPT array is decondensed in protoplast nuclei. FISH signals (red; top and bottom panels) for the HPT sequence localize at mini-chromocenters (brightly fluorescent areas) in nuclei of Arabidopsis Line A. DAPI-stained (top and middle panels) minichromocenters are no longer visible in protoplasts and the FISH signal for the HPT sequence is decondensed. The bottom four panels are higher magnifications of the HPT regions. Bar, 5 µm.