Figure 7.

mnm loss-of-function affects cell cycle progression. (A and B) Fluorescence-activated cell sorting (FACS) traces. Red curves are GFP⁺-expressing cells and blue are GFP⁻ cells. DNA content (x-axes) is plotted against the percentage of maximal absorbance (y-axes). Insets show the percentages of cells in each genotype distributed between the phases G1, S, and G2/M. Cells were prepared from third larval wing imaginal discs containing hs:FLP-induced, GFP-marked mosaic clones, 24 hr after clone induction. (A) Control discs in which both the GFP⁺ and GFP⁻ cell populations are mnm⁺. Note that the red and blue curves are superimposed with major peaks interpreted as 2N and 4N DNA content. (B) Cells prepared from imaginal discs in which the GFP⁺ cells are either mnm⁺ homozygotes or mnm⁺/mnm^PX1. As mnm is recessive, all the GFP⁺ cells are phenotypically wild type. The GFP⁻ cells are mnm^PX1 homozygotes. Note the rightward shift of the GFP⁻ mnm mutant cells, suggesting elevated DNA content, and an increased percentage of cells are scored as G2/M. (C–F) Third instar eye-imaginal discs, with fields shown posterior to the morphogenetic furrow, containing GFP-marked mnm^PX1 homozygous clones. Anterior is to the right and C–F are to the same scale (bar in F). GFP is green and the antigens are in red: (C) Cyclin E (G1 phase), (D) BrdU (S phase), (E) Cyclin A (G2 phase), and (F) phosphorylated Histone H3 (pH3, M phase). Note that mnm^PX1 mutant cells can express all four of these markers (black arrows), indicating that no cell cycle phase is absent.