ISSN:
0730-2312
Schlagwort(e):
sea urchins
;
copper ions
;
hydrogen peroxide
;
hypochlorous acid/hypochlorite
;
myeloperoxidase
;
spermicidal activity
;
Life and Medical Sciences
;
Cell & Developmental Biology
Quelle:
Wiley InterScience Backfile Collection 1832-2000
Thema:
Biologie
,
Chemie und Pharmazie
,
Medizin
Notizen:
Sea urchins have elaborated multiple defenses to assure monospermic fertilization. In this work, we have concentrated on a study of the mechanism(s) by which hydrogen peroxide (H2O2) prevents polyspermy in Arbacia punctulata. We found that it is not H2O2 but probably hypochlorous acid/hypochlorite (HOCl/OCl-) derived from H2O2 that is toxic to the supernumerary sperm. The spermicidal activity of H2O2 is potentiated by at least one order of magnitude by cupric ions (Cu2+). This increased toxicity is not due to the formation of hydroxyl radicals (·OH) because ·OH scavengers did not counteract the activity of Cu2+. More-over, substitution of Cu2+ by ferrous ions (Fe2+), which are known to cause formation of ·OH from H2O2, had no effect on fertilization even at 102-103 times higher concentrations. In contrast, 3-amino-1,2,4-triazole (AT), an HOCl/OCl- scavenger, totally reversed the toxic effects of Cu2+. Furthermore, we found that HOCl/OCl- is generated in solutions of H2O2 and Cu2+ in the presence of 0.5 M NaCl and that its accumulation is abolished by AT. Thus it is possible that the antifertility properties of copper are due to its ability to mediate formation of HOCl/OCl-. HOCl/OCl- generated by Cu2+ from H2O2 and Cl-, a low concentration of exogenously added HOCl/OCl-, or increased concentrations of H2O2 has similar inhibitory effects on the fertilization process in sea urchins. Therefore, we suggest that polyspermy is prevented by the action of a myeloperoxidase that affects the formation of HOCl/OCl- from the Cl- present in sea water through reaction with H2O2 generated by the newly fertilized egg.
Zusätzliches Material:
4 Ill.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1002/jcb.240300302
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