Fig. 5. Visualization of chromosome content by FISH. Fluorescence in situ hybridization was carried out with a single copy probe corresponding to the tagB/tagC/tagD locus on chromosome 4. The representative images are two-dimensional projections of the three-dimensional images used to score the presence of the locus. The percentage of nuclei with a single observable locus is shown. (A) Amoebae that had been developing for six hours on filters showing 4 of 6 nuclei that clearly contain two loci and two nuclei that were counted as having a single locus. Arrows point to signals within these two nuclei considered too weak to be scored as a locus. (B) Amoebae that had emerged from spores that were germinating for 12 hours showing eight nuclei that contain a single tag/C/D locus.