Fig. 3. skpA mutants exhibit cell cycle defects. (A-E) Quantification of cell cycle parameters. The CNSs from wildtype and skpA^– larvae of the indicated ages were assayed for different cell cycle parameters. (A) Mitotic index is the number of phosphorylated-histone H3 (P-histone H3)-positive cells per squashed field observed with a 100x objective. (B) S phase index is the number of BrdU-incorporating cells relative to the volume of DNA staining determined from whole mount confocal analyses. (C) 2C:4C ratio is the ratio of cells with a 2C versus a 4C DNA content, determined from CCD images of DAPI-stained squashed CNSs. (D) Apoptosis index is the number of TUNEL-positive cells relative to the volume of DNA staining. (E) S phase (%) is the percentage of BrdU-incorporating salivary gland or fat body nuclei relative to the total number of nuclei from larvae 3.5 days AED. Error bars in B, D and E represent one standard deviation (n4 CNSs). (F-H) Examples of BrdU incorporation and TUNEL-labeling in wildtype and mutant tissues. Projections of confocal sections through entire CNSs (F,G) or salivary glands and fat bodies (H) are shown. Note the skpA^– imaginal disc (I.D.) with many TUNEL+ cells (G'). No BrdU-incorporating nuclei were observed in skpA^– fat bodies (F.B.), in contrast with the neighboring salivary glands (S.G.) (H'). Bar, 30 µm.

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