Figure 2.

Spatiotemporal Dynamics of Ca²⁺ in Growth Cones Responding to Localized IP₃ Signals

(A) Pseudo-color Ca²⁺ images in WT, R1KO, and R3KO growth cones 0.5 min before and 1.5 min after the onset of repetitive FLIP of caged IP₃. The red crosshairs represent the sites of laser irradiation. Relative changes in Fluo-8H fluorescence (F/F_base, defined as F′) were used as a measure of cytosolic Ca²⁺ levels. The near side ROI (red) was defined as a circular region whose center corresponded to the site of laser irradiation and whose diameter equaled to one-third of the width of each growth cone. The far side ROI (blue) was defined as a circular region of the same diameter that was placed on the center of the far-side half of each growth cone. Scale bar, 5 μm.

(B) Time course changes in F′ in the near (red line) and far (blue line) ROIs positioned on WT (dotted line), R1KO (finely dotted line), and R3KO (solid line) growth cones. Data are represented as mean ± SEM.

(C and D) The mean amplitude of F′ during 90–120 s (C) and earlier periods (D) after the onset of repetitive FLIP shown in (B). Data on WT, R1KO, and R3KO neurons were included in (C), and data on only R3KO neurons in (D). Each gray line connecting two dots represents data from the near and far ROIs of a single growth cone, and each colored bar represents the mean. ∗p < 0.05; ∗∗p < 0.01; ns, not significant; paired t test.

See also Figure S2.