Independent Initiation of Calcium Dependent Glycosidase Release and Cortical Contractions during the Activation of Ascidian Eggs: (Ascidian, Ryanodine, Thimerosal, Thapsigargin, N-acetylglucosaminidase).

During fertilization or ionophore induced activation, ascidian eggs rapidly release cell surface N-acetylglucosaminidase activity used in the block against polyspermy and undergo cortical contractions before they re-initiate meiosis. To better understand the activation process, we probed the relationship between these two processes in Ascidia ceratodes eggs by activating with different agents that increase intracellular Ca levels and under different ionic conditions. Glycosidase activity release was followed by the use of a fluorogenic substrate, and cortical contractions were followed by examining changes in cell shape with light microscopy.