Fig. 7. TEA stimulates MO fusion by a Ca²⁺-dependent mechanism. (A) Spermatids were loaded with 1 mM EGTA and BAPTA-AM for 30 minutes at the indicated concentrations, and the percentage of cells displaying normal MO fusions were counted. Data are representative of three independent experiments. (B) Spermatids treated with EGTA only or with 10 µM BAPTA-AM. Pseudopod formation also appears to be inhibited at high BAPTA-AM concentrations. (C) fer-1 mutant sperm are hypersensitive to internal calcium depletion. Wild-type or fer-1 mutant sperm were incubated in EGTA or 1 µM BAPTA-AM for 30 minutes, then activated in 100 mM TEA in the presence of FM1-43, and scored for normal MO fusion. (D) Sample cells of each of the mutants treated with EGTA (top) or 1 µM BAPTA-AM (bottom). The domain in which the mutation lies is indicated above the images. Arrowheads indicate spermatozoa that have attempted to generate pseudopods, but have no fused MOs. ^*Significantly different (P<0.01) from EGTA-treated cells with the same mutation. Error bars=s.e.m.