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Updated: Sep 23, 2026

Recording Electrical Currents across the Plasma Membrane of Mammalian Sperm Cells
Published on: February 14, 2021
Phospholipase C-dependent Ca2+ release by worm and mammal sperm factors
Kethurah P Howell1, Aurelia Skipwith, Antony Galione
1Department of Biology, Howard University, 415 College Street, NW, Washington, DC 20059-0001, USA.
Abstract:
Egg activation in all animals evidently requires the synthesis of inositol 1,4,5-trisphosphate (InsP(3)) from phosphatidylinositol 4,5-bisphosphate (PIP(2)) by phospholipase C (PLC). Depending on the organism, InsP(3) elicits either calcium oscillations or a single wave, which in turn initiates development. A soluble component in boar sperm that activates mammalian eggs has been suggested to be a PLC isoform. We tested this hypothesis in vitro using egg microsomes of Chaetopterus. Boar sperm factor elicited Ca(2+) release from the microsomes by an InsP(3)-dependent mechanism. The PLC inhibitor U-73122, but not its inactive analog U-73343, blocked the response to sperm factor but not to InsP(3). U-73122 also inhibited the activation of fertilized and parthenogenetic eggs. Chaetopterus sperm also contained a similar activity. These results strongly support the hypothesis that sperm PLCs are ubiquitous mediators of egg activation at fertilization.
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