Ca~(2+) and H~+ Ion Fluxes near the Surface of Gravitropically Stimulated Phycomyces Sporangiophore

摘要

The single-celled fungus Phycomyces blakesleeanus forms vertically oriented sporangiophores from hyphae, which display a negative gravitropic response. Longitudinal growth and gravitropic bending of these sporangiophores were measured with noninvasive H~+ and Ca~(2+) ion-selective microelectrode measurements. The directions of H~+ and Ca~(2+) fluxes, recorded at different locations of sporangiophores, were opposite when the sporangiophores were kept in vertical position. Ca~(2+) fluxes were in most experiments positive (efflux), while H~+ fluxes were negative (influx). The direction of ion fluxes depended on developmental stage of sporangiophores and changed with gravistimulation.