FIG. 8.

Endogenous Aurora-A exhibits biphasic pattern of hyperphosphorylation and activation during meiosis I-meiosis II transition. (A) Oocytes were either left unstimulated (germinal vesicle) or stimulated with progesterone. Individual oocytes were lysed at the time of appearance of the maturation spot (GVBD) or at the indicated times following GVBD. Extracts were subjected to immunoblotting with anti-Aurora-A antibodies (upper panel) or to MPF assays (lower panel). Shown is a representative of three independent experiments. (B) Oocytes were either left unstimulated (germinal vesicle) or stimulated with progesterone. At GVBD or 1 h or 3 h following GVBD, 30 oocytes were withdrawn and lysed. Extracts were subjected to immunoblotting with anti-Xenopus MAP kinase (xMAPK blot) or anti-Aurora-A (AUR-A blot) antibodies. MPF assays were carried out with extracts without prior fractionation, whereas Aurora-A kinase assays were carried out following immunoprecipitation (IP) with antibodies against Aurora-A. Shown is a representative of three independent experiments.