Fig. 1.

Effect of wild-type drosophila CaM (dCaM) and a mutant CaM that cannot bind Ca²⁺(dCaM₁₂₃₄) on the appearance of Ca²⁺ sparks in diaphragm. A: representative ΔF/F images showing the occurrence of Ca²⁺ sparks (arrowheads). B: under control conditions (circles) Ca²⁺spark frequency shows a time-dependent increase, peaking at 394 s. Wild-type dCaM (triangles) decreases the frequency of Ca²⁺sparks. dCaM₁₂₃₄ (squares) results in an increase in the frequency of Ca²⁺sparks and a shift in the time of peak frequency to 516 s. C: dCaM₁₂₃₄ increases the average frequency of Ca²⁺spark occurrence by about 169% over the entire recording time. *P < 0.05 vs. control and wild-type dCaM.