Induction of the cortical reaction in isolated sea urchin egg cortices: effects of Ca2+ and ionophore A23187.
The cortical reaction in isolated sea urchin (Strongylocentrotus purpuratus) egg cortices has been monitored with phase-contrast video microscopy. It was confirmed that the cortical reaction is induced by exposure to Ca2+. No induction was observed after exposure to the Ca2+-ionophore A23187, although the cortices remain sensitive to a subsequent exposure to Ca2+, and the cortical reaction in unfertilized eggs suspended in cortex isolation medium remains inducible by exposure to A23187. These results imply: (1) that A23187 does not induce the cortical reaction directly; (2) that the release of intracellular Ca2+, through which A23187 induces the cortical reaction, is not from storage sites localized entirely in the cortex; and (3) that intracellular storage sites for the Ca2+ involved in the cortical reaction are also present outside the cortex.
Semancik
G J
GJ
Department of Biology, Georgetown University, Washington, D.C. 20057.
Shust
N M
NM
Byrnes
S A
SA
Nishioka
D
D
D000818:Animals; D000001:Calcimycin / Q000494:pharmacology*; D002118:Calcium / Q000494:pharmacology*; D002462:Cell Membrane / Q000378:metabolism / Q000648:ultrastructure; D005089:Exocytosis / Q000187:drug effects; D015388:Organelles / Q000378:metabolism; D010063:Ovum / Q000187:drug effects / Q000502:physiology* / Q000648:ultrastructure; D012617:Sea Urchins / Q000166:cytology
D000001:Calcimycin; D002118:Calcium