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Making waves in eggs

Fertilization of animal and plant eggs triggers one or more Ca²⁺ waves that are propagated across the egg by a network of ER Ca²⁺-release sites. These waves are initiated at specific pacemaker sites in response to sperm-triggered production of inositol 1,4,5-trisphosphate [Ins(1,4,5)P₃] from phosphatidylinositol 4,5-bisphosphate [PtdIns(4,5)P₂]. But what controls their dynamics and why do the wave patterns differ in some organisms? In a Commentary on p. 3557, Rémi Dumollard and co-workers review work that is shedding light on how such Ca²⁺ waves are generated. The pacemakers appear to be located in cortical ER-rich domains comprising densely packed sheets and tubes of ER membrane. Studies of mice eggs indicate that these domains contain clustered type I Ins(1,4,5)P₃ receptors (IP₃RIs) that release Ca²⁺ into the cytoplasm; the pacemakers are thus sites that have enhanced sensitivity to Ins(1,4,5)P₃. In ascidians, by contrast, the pacemaker site is defined instead by a localized source of Ins(1,4,5)P₃ production — probably PtdIns(4,5)P₂-rich microvilli — and this explains the different characteristics of the Ca²⁺ waves in these eggs.

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Calcium wave pacemakers in eggs

Rémi Dumollard, John Carroll, Geneviève Dupont, and Christian Sardet
JCS 2002 115: 3557-3564. [Abstract] [Full Text]  

This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Related articles in JCS Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Search for Related Content Social Bookmarking                         What's this?