Figure 2.

Fluorescence in situ hybridization analysis of ES cell clones with Cre-mediated chromosome rearrangements. (a) Simultaneous hybridization with BACs 174J11 and 213A6 to metaphase spreads of ES cell line Vc1. The outside probe BAC 213A6 (green) hybridized to both copies of MMU16, and the inside probe BAC 174J11 (red) colocalized with the outside probe only on one homolog (arrow). The presence or absence of a duplication could not be resolved on metaphase chromosomes. (b and c) Simultaneous hybridization to interphase nuclei of cell line IIb4. The inside probe (red) was colocalized with the outside probe (green) in 74% (66/89) of the nuclei. In 24% of the nuclei, duplicate signals representing hybridization to G₂ cells were observed. (d and e) Simultaneous hybridization to interphase nuclei of cell line Vc1. The inside probe (two red dots) colocalized with the outside probe in 57% of nuclei (49/86). In 31% of the nuclei duplicate signals from G2 cells were observed.