title: Calcium transients during early development in single starfish (Asterias forbesi) oocytes.
abstract: Maturation and fertilization of the starfish oocyte are putative calcium-dependent events. We have investigated the spatial distribution and temporal dynamics of this calcium dependence in single oocytes of Asterias forbesi. We used the calcium photoprotein, aequorin, in conjunction with a microscope-photomultiplier and microscope-image intensifier. Surprisingly, in contrast to earlier work with Marasthenias glacialis, there is no detectable increase in intracellular-free calcium in the oocyte of A. forbesi in response to the maturation hormone 1-methyl adenine. During fertilization of the same, matured, A. forbesi oocyte there is a large increase in intracellular-free calcium. The calcium concentration increases to approximately 1 microM at the point of insemination and the region of elevated free calcium expands across the oocyte in approximately 20 s (17-19 degrees C). After the entire oocyte reaches an elevated concentration of free calcium, the concentration decreases uniformly throughout the oocyte over the next several minutes.
mesh_terms: D000225:Adenine / Q000031:analogs & derivatives / Q000494:pharmacology; D000331:Aequorin; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D005260:Female; D005306:Fertilization; D008163:Luminescent Measurements; D009865:Oocytes / Q000187:drug effects / Q000502:physiology*; D013215:Starfish / Q000502:physiology*
chemical_list: D000331:Aequorin; C008407:1-methyladenine; D000225:Adenine; D002118:Calcium