Figure 2.

Fertilization of the sea urchin eggs pretreated with GPN. P. lividus eggs were fertilized following the pretreatments described in the Materials and Methods. (A) Pseudocolor images of the instantaneous changes of the Ca²⁺ signals at several key moments of the propagating wave in representative eggs. The arrow indicates the intracellular Ca²⁺ increase at the spot of the sperm-egg interaction site. (B) The quantified Ca²⁺ increases in the control (green curves) and GPN-pretreated (200 µM, brown curves) eggs in one of the four independent experiments. (C) Dose-dependent effects of GPN on the elevation of the FE and polyspermy. Sperm inside the fertilized eggs were visualized with the Hoechst 33342 (arrows), scale bar 20 µm. (D) The average numbers of the egg-incorporated spermatozoa were provided as Mean ± SD (bars) and the FE elevation as a frequency (line).