Figure 7.

Calcium responses of mouse sperm were suppressed by the bitter blocker and abolished by the Gnat3 gene knockout. (A) A response trace from a representative sperm: the increase in the intracellular calcium concentration was significant in response to 300 μM PTC alone, nearly undetectable after the incubation with 1 mM probenecid and partially recovered after the wash-off of probenecid (arrows). (B) Quantification of the peak responses from 26 sperm at the three different time points described in (A). Values are mean ± SE. (C) Probenecid has no inhibitory effect on the response to cycloheximide. (D) Sperm isolated from the Gnat3^−/− mutant mice did not respond to 2 mM salicin, PTC, denatonium (Dena), 6 propyl-2-thiouracil (PROP), cycloheximide (Cyclo) but did respond to 2 mM ATP (177 sperm imaged and only 3 cells' traces shown).