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Fertilization envelope formation induced by melittin in sea urchin eggs does not depend on Ca 2+ signalling
Author(s) -
Tojo Tadashi,
Kamata Yasuyuki,
Fujiwara Akiko,
Yasumasu Ikuo
Publication year - 1995
Publication title -
development, growth and differentiation
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.864
H-Index - 66
eISSN - 1440-169X
pISSN - 0012-1592
DOI - 10.1046/j.1440-169x.1995.00006.x
Subject(s) - melittin , sea urchin , human fertilization , egta , intracellular , biophysics , chemistry , biology , calcium , membrane , biochemistry , microbiology and biotechnology , anatomy , organic chemistry
In sea urchin eggs, 10 μg/mL melittin was found to induce fertilization envelope formation without any increase in [Ca 2+ ] i (the intracellular free Ca 2+ level). On the other hand, 10 μmol/L Br‐A23187 and 100 μg/mL SDS induced fertilization envelope formation associated with [Ca 2+ ] i increase. If EGTA was injected into eggs to make an intracellular concentration of 2 mmol/L, [Ca 2+ ] i became quite low and was not altered by melittin, or by Br‐A23187 and SDS. In eggs containing EGTA, fertilization envelope formation was induced by melittin even in Ca 2+ ‐free artificial sea water, but not by Br‐A23187 or SDS. Thus [Ca 2+ ] i is essential for induction of a fertilization envelope in sea urchin eggs by Br‐A23187 or SDS but not by melittin. Melittin probably activates some Ca 2+ ‐independent reaction downstream of Ca 2+ ‐dependent reactions in a sequential reaction system that finally results in fertilization envelope formation.