Fig. 1

Cytosolic Ca²⁺ patterns in gastrula stage embryos. (A–C) Ratiometric imaging of cytosolic Ca²⁺ patterns at 6 hpf during normal development. (D–F) Cytosolic Ca²⁺ patterns at 6 hpf following inhibition of the ER Ca²⁺ pump with 0.5 μM thapsigargin from 4 to 6 hpf. Ca²⁺ concentrations are elevated in all embryonic regions, including the ventral margin (v), dorsal margin (d), and dorsal forerunner cells (DFC). (A and D) Overlay of bright field (grey-scale), the calcium indicator Oregon Green BAPTA-1 dextran (green), and the calcium-insensitive control Texas Red dextran (red). (B and E) Overlay of Oregon Green BAPTA-1 dextran and Texas Red dextran. (C and F) Pseudocolored ratiometric images (green/red). (G) The bar graph shows average cytosolic Ca²⁺ concentrations in the ventral margin (V), dorsal margin (D), and dorsal forerunner cells (DFC). The average Ca²⁺ concentration was measured in a circular region of interest with a diameter of 40 μm (ventral and dorsal margin) or 20 μm (dorsal forerunner cells). In the DMSO-treated controls, Ca²⁺ concentrations are significantly lower in the dorsal margin and DFC compared to the ventral margin (two-tailed t-test, P < 0.05, n = 13). Ca²⁺ concentrations increase significantly in the ventral margin, dorsal margin, and dorsal forerunner cells following treatment with 0.5 μM thapsigargin from 4 to 6 hpf (two-tailed t-test, P < 0.05, n = 13). Scale bar = 200 μm.