Quantitative analysis of concentration gradient and ionic currents associated with hyphal tip growth in fungi

It has been shown previously that the nutrient gradient generated by a tip growing elongated cell induces an ionic current entering the cell tip and l ooping back in the extracellular medium CL. Limozin, B. Denet and P. Pelce, Phys. Rev. Lett. 78, 4881 (1997)]. We apply this mechanism to the case of hyphae of fungi, using realistic cell geometries, symport kinetics, proton pump permeabilities, and buffer concentrations. We show that this mechanism contributes to a noticeable part of the external current intensity, relate d inner electrical field and pH gradient, in agreement with experimental me asurements. This provides a good example in biological cells of interaction between shape and field, a common property of growing nonliving systems, s uch as crystalline dendrites or electrodeposition.