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Inositol tri‐phosphate in human and ascidian spermatozoa
Author(s) -
Tosti Elisabetta,
Palumbo Anna,
Dale Brian
Publication year - 1993
Publication title -
molecular reproduction and development
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.745
H-Index - 105
eISSN - 1098-2795
pISSN - 1040-452X
DOI - 10.1002/mrd.1080350109
Subject(s) - spermatozoon , biology , ionophore , ciona intestinalis , inositol , phosphatidylinositol , calcium , acrosome reaction , microbiology and biotechnology , biochemistry , inositol phosphate , calcium in biology , acrosome , phosphate , intracellular , oocyte activation , inositol trisphosphate , medicine , anatomy , oocyte , human fertilization , signal transduction , semen , receptor , in vitro , embryo , membrane , gene
Using a specific protein binding assay we have shown that a spermatozoon of the ascidian Ciona intestinalis contains 1.58 ± 0.74 × 10 −19 moles of inositol 1,4,5‐tri‐phosphate (InsP 3 ), while a human spermatozoon contains 6.4 ± 0.14 × 10 −19 moles. Induction of the acrosome reaction (AR) in both species, by exposure to the calcium ionophore A23187, does not significantly alter levels of InsP 3 , suggesting that phosphatidylinositol (PI) turnover is not necessary for the calcium ionophore induced AR. Furthermore, PI turnover in ascidian spermatozoa appears to be insensitive to lithium and phorbol ester. The high intracellular concentration of InsP 3 in spermatozoa, corresponding to 50–200 μM, suggests it may play a role in egg activation. © 1993 Wiley‐Liss, Inc.