title: Calcium Signaling in Mammalian Eggs at Fertilization.
abstract: The innovation and development of live-cell fluorescence imaging methods have revealed the dynamic aspects of intracellular Ca2+ in a wide variety of cells. The fertilized egg, the very first cell to be a new individual, has long been under extensive investigations utilizing Ca2+ imaging since its early days, and spatiotemporal Ca2+ dynamics and underlying mechanisms of Ca2+ mobilization, as well as physiological roles of Ca2+ at fertilization, have become more or less evident in various animal species. In this article, we illustrate characteristic patterns of Ca2+ dynamics in mammalian gametes and molecular basis for Ca2+ release from intracellular stores leading to the elevation in cytoplasmic Ca2+ concentration, and describe the identity and properties of sperm-borne egg-activating factor in relation to the induction of Ca2+ waves and Ca2+ oscillations, referring to its potential use in artificial egg activation as infertility treatment. In addition, a possible Ca2+ influx-driven mechanism for slow and long-lasting Ca2+ oscillations characteristic of mammalian eggs is proposed, based on the recent experimental findings and mathematical modeling. Cumulative knowledge about the roles of Ca2+ in the egg activation leading to early embryogenesis is summarized, to emphasize the diversity of functions that Ca2+ can perform in a single type of cell.
authors.affiliation: Department of Engineering Science, The University of Electro-Communications Graduate School of Informatics and Engineering, 1-5-1 Chofugaoka, Chofu, Tokyo 182-8585, Japan. hshrkw@uec.ac.jp.
authors.forename: Hideki
authors.initials: H
authors.lastname: Shirakawa
authors.forename: Takashi
authors.initials: T
authors.lastname: Kikuchi
authors.forename: Masahiko
authors.initials: M
authors.lastname: Ito
mesh_terms: D000818:Animals; D020013:Calcium Signaling; D004531:Eggs; D005306:Fertilization; D006801:Humans