meis1 is required for the G1-S transition and the expression of the G1-S regulators cyclin D1 and c-myc. (A-D) Histograms displaying DNA content (cell cycle profile) of cells from dissected 19hpf eyes of meis1-MO treated embryos relative to (A) controls (Crtl-MO), (B) meis1-MO+GFP-meis1 mRNA, (C) meis1-MO+cyclin D1 mRNA, and (D) meis1-MO+c-myc mRNA injected embryos. Number of replicates (n) and P values are indicated. meis1 knockdown induces a delay in G1, which is partially rescued by co-injection of GFP-meis1 (B), cyclin D1 (C) and c-myc (D) mRNAs. (E) Average percentages are shown for G1, S and G2/M DNA content. The cell-cycle profiles of control morphants and of uninjected, wild-type embryos are indistinguishable (not shown). (F-I) In situ analysis of cyclin D1 and c-myc transcription in control (F,H) and meis1 morphants (G,I) at 19hpf. meis1 morphants show a dramatic reduction in cyclin D1 and c-myc in the eye (red arrowheads). cyclin D1 and c-myc are still detected in other body regions (black arrowheads). Hybridization and reaction development were performed strictly in parallel. Representative embryos are shown.