Calcium waves in the the maturing oocyte*

Calcium waves in oocytes are sustained by release of Ca2+ from the endoplasmic reticulum (ER) through clustered release channels.  As the oocytes matures, a) the calcium waves slow down by about a factor of two, b) the overall duration of Ca2+ elevation grows substantially, and c) the cell is more susceptible to wave initiation. At the same time, the kinetics of release of Ca2+ from a single cluster is changed only insignificantly. Based on a computational model that accurately reproduces elemental Ca2+ release kinetics from channel clusters, we propose that the changing spatial organization of signaling effectors is a common underlying cause for all the above described observations as the Ca2+ signaling machinery matures.