Phosphoinositides and phosphatidic acid in pollen tube growth Phosphoinositides and phosphatidic acid regulate pollen tube growth and reorientation through modulation of [Ca]c and membrane secretion

Estimates of caged-release based on photolysis of caged-fluorescein In order to provide estimates on the concentration of PtdIns(4,5)P2 or Ins(1,4,5)P3 released upon photolysis, we quantified the apparent efficacy of caged fluorescein photolysis in the first 40-50 μm of the pollen tube; this probe becomes fluorescent upon photorelease and the light emitted from loaded cells can be compared to known concentrations of the fluorophore from in vitro solutions (Malhó and Trewavas, 1996). The graph below (Fig. S1) depicts the estimated intracellular concentration of caged-fluorescein (X-axis)(based on the fluorescence emitted by the fluorophore upon a 5 sec flash of UV light) in pollen tubes submitted to an osmotic shock in a medium containing variable concentrations of the caged-probe (Y axis).