Fig. 1.

The PI-PLC inhibitor U73122 inhibits Ca²⁺ mobilization, DNA synthesis and exflagellation in P. berghei gametocytes.

A. Effect of U73122 on light emission over time in gametocytes expressing the Ca²⁺-dependent luciferase GFP–aequorin. Representative time-courses show effects of U73122 (upper panels) and U73433 (lower panels) on XA induced Ca²⁺ mobilization (left) compared with effects of compounds alone (right). XA and compounds were added at time point 0 s.

B. Dose-dependent effects of U73122 and U73343 on Ca²⁺-dependent luciferase activity in the presence of 20 µM XA. Relative light units were integrated over the first 50 s after addition of XA + inhibitor.

C. Dose-dependent effects on exflagellation of inhibitors added at the moment of microgametocyte activation, expressed as a percentage of a DMSO control. Asterisks indicate significant differences from solvent controls (*P < 0.01, Student's t-test).

D. Effects on exflagellation of adding 20 µM U73122 or U73343 at different time points after gametocyte activation by XA + pH 8.0. Exflagellation was counted after 12–15 min. Error bars indicate standard deviations among 10 slides from three different experiments.

E. Dose-response of U73122 and U73343 for [³H]hypoxanthine incorporation as a measure of DNA synthesis during microgametogenesis. Compounds and [³H]hypoxanthine were added simultaneously with the activation medium. Error bars in (B), (C) and (E) show standard deviations from 3–4 samples.