Abstract
During cell migration, F-actin is asymmetrically accumulated at the front side of monospores from the marine red alga Porphyra yezoensis. To elucidate how the establishment of cell polarity responsible for the F-actin asymmetry is regulated in monospores, we pharmacologically tested the roles of Ca2+ and phosphatidylinositol pathway in this event. When extracellular Ca2+ was removed by EGTA or Ca2+ influx was blocked by LaCl3, asymmetrical distribution of F-actin was completely inhibited. The same result was observed by the treatment of monospores with phospholipase C (PLC) inhibitor U73122. In contrast, phospholipase D (PLD) inhibitor, 1-butanol, had no effect on the formation of F-actin asymmetry, although migration of monospores was completely inhibited. Therefore, we proposed that in the early development of monospores, Ca2+ influx and PLC activity are participated in the establishment of cell polarity and PLD plays a role in the maintenance of cell polarity.
