Fig. 2. Initiation of betaine transport after parthenogenetic activation with Sr²⁺. The rate of betaine transport was measured as a function of time after activation of mouse MII oocytes by exposure to Sr²⁺ (exposure time indicated by bar). Activated oocytes are indicated by black circles. Control oocytes were treated identically but not exposed to Sr²⁺ (white circles). Parthenogenotes developed to the 2- and 4-cell stages (2c and 4c) at the times indicated. Asterisks indicate significant difference from t=0 (^*P<0.05, ^***P<0.001; ANOVA and Tukey-Kramer post-hoc test). Each point represents the mean±s.e.m. of three independent measurements, except for t=0 where there were ten (s.e.m. smaller than symbol and not shown).