Abstract
Summary: Rhodotorucine A is a mating pheromone produced by mating type A cells of Rhodosporidium toruloides which induces mating tube formation in mating type a cells. Rhodotorucine A induced conspicuous changes in Ca2+ fluxes in the target cells which consisted of a very rapid, transient Ca2+ influx immediately after pheromone addition and a gradual Ca2+ accumulation during mating tube elongation. The magnitude of the pheromone-induced changes of Ca2+ fluxes was correlated with the efficiency with which the pheromone elicits biological responses in mating type a cells. Compared to vegetative growth, the response to the pheromone was highly sensitive to trifluoperazine, an inhibitor of calmodulin. Trifluoperazine inhibited exclusively the emergence and the elongation of mating tubes but not the signalling reaction.