Premium
Effect of maitotoxin on sea urchin egg fertilization and on Ca 2+ permeabilities of eggs and intracellular stores *
Author(s) -
Pesando Danielle,
Girard JeanPierre,
DurandClément Monique,
Payan Patrick,
PuiseuxDao Simone
Publication year - 1991
Publication title -
biology of the cell
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.543
H-Index - 85
eISSN - 1768-322X
pISSN - 0248-4900
DOI - 10.1016/0248-4900(91)90297-z
Subject(s) - sea urchin , biology , human fertilization , intracellular , verapamil , gamete , endoplasmic reticulum , exocytosis , toxin , biophysics , oocyte activation , calcium , biochemistry , microbiology and biotechnology , membrane , embryo , medicine , embryogenesis , anatomy
Summary— Maitotoxin (MTX), a potent marine toxin involved in ciguatera poisoning, inhibited sea urchin egg fertilization in a dose‐dependent manner with an IC 50 of 7 .5 × 10 −3 MU (mouse‐unit)/ml. It did not affect male gametes fertilizing capabilities but provoked exocytosis in female gametes. It induced a K + loss simultaneously with a Na + entry into unfertilized eggs and increased the Ca 2+ influx at higher concentrations. On isolated cortex preparations, high concentrations of MTX reduced the rate of ATP‐dependent ca 2+ accumulation into reticulum compartments and caused a leakage of Ca 2+ from a preparation pre‐loaded with 45 Ca 2+ . Verapamil (10 −4 M) similarly blocked the increase of egg permeability to Ca 2+ and the effect on Ca 2+ sequesting into intracellular compartment, induced by MTX. Ion transport perturbations which evolved relatively slowly are probably not the direct cause of fertilization inhibition which could be related to a modification of the plasma membrane of the female gametes by this hydrophilic toxin.