Figure 1. Chromosome painting in primates with human chromosome-specific probes. Painting probes have been labelled with five different fluorochromes in Boolean combinations to differentiate all 24 human chromosomes and their primate homologues. (a) Painting to a human metaphase and (b) painting to the chromosomes of a gibbon (Hylobates concolor) showing numerous reciprocal translocations which distinguish humans from this gibbon. Reprinted with permission from Schröck E et al. (1996) Multicolor spectral karyotyping of human chromosomes. Science 273: 494–497. Copyright © 1996 American Association for the Advancement of Science.

Figure 2. Chromosomes of the Indian muntjak (2N = 6,7) hybridized with sheep (2N = 54) chromosome-specific DNA probes on the X- and Y₁-chromosome. From top: sheep chromosome 1 probe in blue, 4 in green, 16 in yellow, 12 in pink, 6 in red, and 10 in light blue. Note that in this cell line there is a small deletion on the X- chromosome in the region of the yellow and pink signals. The sheep chromosome 1 probe gives also two signals on muntjak chromosome 1. The hybridization pattern indicates that fusions of entire homologous chromosomes led to the low diploid number and large chromosomes of the Indian muntjac. Kindly provided by S. Müller and L. Frönicke based in Münich, Germany.

Figure 3. The evolution of human chromosome 2 analysed with chromosome-specific painting probes derived from the chimpanzee. Primates show two homologues for human chromosome 2: one for the long and one for the short arm. The fusion of the two chromosomes occurred after the divergence of apes and humans. The probe from chimpanzee chromosome 12 (green) hybridizes to the short arm of human chromosome 2 but extends to the long arm, indicating that the fusion point is not in the centromere but several bands apart in the long arm. The remaining segment of human chromosome 2q is hybridized by the chimpanzee chromosome 13 probe (red). Kindly provided by S. Müller based in Münich, Germany.

Figure 4. Human chromosomes were stained with a green fluorescent dye (DAPI) that is specific for AT-rich DNA. The chromosomes were also probed by in situ hybridization using a red fluorescing Alu DNA sequence. (a) The green and red images of five chromosomes are offset. (b) The images are superimposed. The late replicating AT-rich G bands fluoresce green. The early replicating GC-rich R bands do not fluoresce with DAPI but fluoresce red with the Alu probe. Reproduced from Korenberg JR and Rykowski MC (1988) Human genome organization: Alu, lines and the molecular structure of metaphase chromosome bands. Cell 53: 391–400, with permission from Elsevier.