Fig. 3.

Ionomycin treatment induces a zinc spark in bovine eggs. (a) Time course montage of Zn²⁺ and Ca²⁺ fluxes in a bovine egg treated with 50 μM Ca-ionomycin. Extracellular Zn²⁺ and intracellular Ca²⁺ were monitored using 50 μM FZ3 and 5 μM Fluo4-AM (Fluo4) respectively. (b) Representative time traces of normalized Fluo4 (black) and FZ3 (green) fluorescence. Zn²⁺ release occurs simultaneously with the rise in [Ca²⁺]i within the experimental time resolution (2 s). Scale bars, 20 μm. (c) Time course montage of Zn²⁺ release from a bovine egg treated with 50 μM Ca-ionomycin. Extracellular Zn²⁺ was monitored using 50 μM Fluozin-3 (FZ3). We note that the zona pellucida in these cells contains enhanced Fluozin-3 fluorescence, as is seen in the ring structure (white arrow, leftmost panel) surrounding the main body of the egg (*). (d) Representative time traces of normalized FZ3 extracellular fluorescence (F/F0) showing the range of signal intensities observed. Of the 33 eggs monitored, 14 displayed a small spark intensity, 13 displayed a medium spark intensity, 1 displayed a large spark intensity, and 4 did not spark. Please see Videos S1 and S2 for live imaging of zinc sparks. (For interpretation of the references to colour in this figure legend, the reader is referred to the Web version of this article.)