Calcium efflux during germination ofBlastocladiella emersonii

Preloaded zoospores ofBlastocladiella emersonii were found to release large quantities of⁴⁵Ca²⁺ in the course of germination, whereas no calcium is released from nongerminating zoospores. Studies with inhibitors of germination and of calcium movement seem to support the existence of two temporally as well as developmentally distinct effluxes during this differentiative transition. The early efflux seems to be associated with the triggering of the process and begins prior to other known structural and physiological responses of the zoospores; the late efflux starts just prior to the appearance of the first germling cells and is probably related to the morphological progress of germination. The early efflux of calcium per se is not sufficient to elicit the process, since the calcium ionophore A23187 produces a comparable efflux, but induces germination only in the presence of noneffective cyclic AMP concentrations.