Fig. 3.

TRIP-mediated chromosome loss and cell death is specific to proliferating cells. (A) Immunodetection of the activated form of caspase 3 on cryosections of invloxP/+ and invloxP/+;LMOP-Cre retinas at P9 and P22. Nuclei were counterstained with DAPI. Some apoptotic cells (arrowheads) were detected in the inner nuclear layer (INL) at P9. No difference was detected between control and mutant retinas. (B) Scheme of wild-type, noninverted, and inverted loxP-carrying Chr2. LoxP sites (triangles) and primers used for PCR (black arrows) and real-time PCR (red arrows) are indicated. (C) PCR detection of DNA inversion in invloxP/+;LMOP-Cre retinas at P22. Cre-mediated inversion of the DNA fragment flanked with loxP sites is detected with the AC and BD primer sets. (D) Percentage of inverted allele (primer pair 5–6) in control and mutant retinas, at P9 and P22. If Cre is active in all photoreceptors, the percentage of inverted allele should be 50% on average, as the inversion is reversible (this theoretical percentage is indicated by a dotted line). (E) Quantification of loxP-carrying allele (primer pair 3 and 4) versus wild-type allele (primer pair 1 and 2) in control and mutant retinas at P9 and P22. Data are presented as means ± SEM. Quantification resulted from average of three independent quantitative PCR reactions. Number of animals for each type and P values from unpaired t test are indicated. ONL, outer nuclear layer; INL, inner nuclear layer. (Scale bar: 50 μm.)