ER-released Ca2+ is essential for the fast polyspermy block. Representative fertilization recordings made in the presence of 500 nM Xestospongin C (XC; A), vehicle (2% DMSO; C), or 100 µM 2-APB (F). Dashed line denotes 0 mV, and arrows indicate sperm additions. Tukey box plot distributions of the resting (B) and fertilization (D) potentials, as well as the depolarization rates (E), from recordings made in the indicated treatments (n = 5–8, 2–4 experiment days per treatment). In B and D, the gray lines behind the box plots represent the Tukey box plot distributions for the control (MR/5) data, where the solid line represents the median value, the dashed lines denote the data spread from 25 and 75%, and the whiskers reflect 10–90%. (G) Proportion of polyspermic embryos out of total developed embryos in vehicle (2% DMSO in MR/5), Xestospongin C, control (MR/5), and 2-APB (n = 3, recorded over 3 experiment days per treatment, the mean values ± SEM are reported). *, P < 0.05.
