Fig. 7. Cdc25C overexpression disrupts gastrulation. (A,B) The two dorsal blastomeres of four-cell embryos were injected with ß-gal RNA (4 ng) or co-injected with ß-gal (100 pg) and His-Cdc25C (3 ng) and embryos were scored for gastrulation defects at stage 11.5-12. Number of embryos examined: Cdc25C (n=141), ß-Gal (n=162). (A, lower panels) Stage 10.5-11 embryo lysates were examined by immunoblot analysis using anti-His-epitope, Cdc2 and phospho-Cdc2 antibodies. (C) Following injection as in A, mitotic nuclei of stage 11 embryos were visualized. Mitotic index (n=10-12 embryos): ß-gal, 8.3% (6928 nuclei), Cdc25C, 28.1% (5550 nuclei). (D,E) Embryos were injected with 4 ng of Cdc25C RNA and either 0, 0.2 or 0.5 ng of Wee1 RNA. Number of embryos examined: Cdc25C + 0 ng Wee1 (n=74), Cdc25C + 0.2 ng Wee1 (n=100) and Cdc25C + 0.5 ng Wee1 (n=86). Note that increased expression of Wee1 counteracts the defects induced by Cdc25C overexpression.