The induction of sporulation in the aquatic fungus Blastocladiella emersonii is dependent on extracellular calcium

Induction of sporulation in Blastocladiella emersonii is absolutely depende nt on extracellular calcium. Vegetative cells grown in media with or withou t calcium do not sporulate in media devoid of calcium or in CaCl2 with EGTA . Calcium channel blockers, CoCl2 and nifedipine, and ionophore A23187 inhi bited the induction of sporulation. The calmodulin antagonists trifluoperaz ine and chlorpromazine inhibited the sporulation when present in the cultur es at least 60 min after induction. So, calcium that is accumulated during growth is not sufficient or is not mobilized to initiate sporulation, and a calcium influx is likely to occur by type II calcium channel functions, es sential for the response to nutritional starvation. A calmodulin-like prote in has been suggested to mediate calcium events in sporulation. (C) 1999 Fe deration of European Microbiological Societies, Published by Elsevier Scien ce B.V. All rights reserved.