Hydrogen peroxide production, chemiluminescence, and the respiratory burst of fertilization: Interrelated events in early sea urchin development

Abstract

After fertilization of the sea urchin, Strongylocentrotus purpuratus, a crosslinked fertilization membrane is formed; the crosslinks (dityrosine residues) are synthesized in a reaction catalyzed by an ovoperoxidase released from the cortical granules during fertilization. The substrate for ovoperoxidase activity, H2O2, is generated by the egg coincident with the respiratory burst that follows parthenogenetic activation by the divalent ionophore A23187 or fertilization. This burst of O2 consumption may be almost quantitatively accounted for by H2O2 evolution, as measured by the peroxidase-catalyzed quenching of scopoletin fluorescence. Neither the burst of O2 consumption nor H2O2 production occurs when the inhibitor of cortical granule discharge, procaine, is present at fertilization. Fertilization or parthenogenetic activation with A23187 is associated with a burst of light emission. This chemiluminescence is inhibited in vivo by inhibitors of the ovoperoxidase, such as 3-amino-1,2,4-triazole, phenylhydrazine, sulfite or azide. A crude ovoperoxidase preparation catalyzes H2O2-dependent chemiluminescence that is similarly inhibited. The bursts of O2 uptake, peroxide production and chemiluminescence appear to be several manifestations of the peroxidative system released at fertilization. This system may additionally be responsible for spermicidal activity, and may act as a component of the block to polyspermy.