Cortical granule translocation during maturation of starfish oocytes requires cytoskeletal rearrangement triggered by InsP(3)-mediated Ca2+ release

Cortical granules (secretory vesicles located under the cortex of mature oo cytes) release their contents to the medium at fertilization. Their exocyto sis modifies the extracellular environment, blocking the penetration of add itional sperm. The granules translocate to the surface during the maturatio n process, and it has been suggested that they move to the cortex via cytos keletal elements. In this paper we show that the increase in intracellular Ca2+, which the maturing hormone 1-methyladenine (1-MA) induces in starfish through the activation of inositol 1,4,5-trisphosphate (InsP(3)) receptors , triggers changes in filamentous actin, which then direct the correct move ment and reorientation of the cortical granules and the elevation of the fe rtilization envelope. (C) 1999 Academic Press.