Figure 6.

Whole-cell recordings from itpr-null mosaics. A, Quantum bumps: 10 superimposed traces (including failures) from responses to 1-ms flashes containing on average ∼0.5 effective photons, recorded with 1 mm EGTA in electrode in wild-type, itpr mosaic null, and itpr/+ heterozygotes (sibling controls). B, Summary of QE in recordings with and without EGTA, normalized to wild-type values. There was no significant effect of EGTA or itpr-null mutation (mean ± SEM; itpr control electrode solution, n = 15 cells; itpr recorded with 1 mm, n = 15; 2 mm EGTA, n = 7; wt and itpr/+ controls, 9–14 cells; p = 0.77, one-way ANOVA). C, Mean bump amplitude was increased in recordings made with EGTA (n = 4–10 cells). D, Dark noise recorded in wild-type and itpr mutants recorded using normal electrode solution (no EGTA); both showed similar levels of dark noise. E, Dark event rates and amplitudes (mean ± SEM) in wild-type (n = 7 cells) and itpr mosaics (n = 11 cells) were similar (p = 0.34 for rates and 0.64 for amplitude, two-tailed t test).