Figure 2.

(A) Centromere specific probes used for detection of chromosome copy number in interphase nuclei. Probes specific for the centromeres of two different chromosomes were hybridized to interphase nuclei. The green probe is present in two copies while the red probe indicates trisomy for this chromosome. The doublet observed for one of the green and one of the red signals is due to either the decondensation of centromere repeat regions of the genome in interphase or the fact that this particular cell is in S-phase and has already replicated these regions. (B) Locus-specific probes for mouse chromosomes. Bacterial artificial chromosome clones specific to single copy regions of the genome have been labeled with either Rhodamine110-dUTP (green) or digoxigenin-dUTP and subsequently detected with mouse antidigoxigenin followed by antimouse TRITC (red). Green signals represent hybridization to mouse chromosome 12D1 and red to band 12E. A chromosome 14 painting probe (yellow) was used to identify the translocation partner. The normal chromosome 12 (bottom arrow) shows hybridization with both chromosome 12 locus specific probes (green and red) while the derivative 12 (top arrow) shows loss of the 12E region probe (no red signal) which occurred during the rearrangement with chromosome 14 (yellow paint). Also of note is the fact that there are no normal chromosome 14 in this metaphase, all having been either deleted (left) or rearranged (remaining three partially painted chromosomes. (C) Chromosome painting probes specific for mouse chromosomes 4 (yellow), 12 (green) and X (red). The chromosome painting enabled the identification of two translocations: T(X,12) and T(4,X).