Figure 7

CATSPER1 is required for the NH ₄ Cl-induced [Ca²⁺] _i rise in mouse sperm. (A-C) Representative responses to 20 mM NH₄Cl in sperm head from a wild-type (A), a Catsper1 null (B), and transgenic sperm expressing an EGFP-CATSPER1 fusion protein on the Catsper1 null background (C). Ionomycin (10 μM, A-C) and EGTA (50 mM) were applied as control stimuli. (D) Averaged ΔF/F₀ changes induced by 20 mM NH₄Cl in wild-type (WT) and Catsper1 null (Mut) sperm. Numbers of analyzed cells are in parentheses. (E) Percentages of sperm responsive to NH₄Cl application in WT (n = 7 imaging runs; 3 mice, 56 cells), Catsper1 null (Mut; n = 7; 3 mice, 31 cells), and the Catsper1 mutant rescued with the EGFP-CatSper1 transgene (Tg; n = 7; 2 mice, 31 cells). Cells from Tg mice were imaged with Fura-2 and the others were imaged with Fluo-4.