The mouse egg provided the first direct measurement of Ca2+ oscillations in any cell type. These sperm-induced Ca2+ oscillations occur at a relatively low frequency, and can be detected up to 18–20 h after sperm–egg fusion. The Ca2+ oscillations consist of two series of transients; the first lasts about 4 h, from metaphase II until interphase of the first cell cycle, and the second lasts the duration of the first mitotic division. This cell-cycle-regulated aspect to the pattern of Ca2+ signalling at fertilization is reflected in the role of the Ca2+ transients in stimulating exit from metaphase arrest. Recent developments have started to shed light on the mechanism initiating Ca2+ oscillations at fertilization, on how the frequency of the oscillations is set, and on what determines their temporal pattern.
Abbreviations used: IP3, inositol 1,4,5-trisphosphate; PLC, phospholipase C; IP3R, IP3 receptor; PKC, protein kinase C; PIP2, phosphatidylinositol 4,5-bisphosphate; PH, pleckstrin homology; GFP, green fluorescent protein; NEBD, nuclear envelope breakdown.
Calcium Oscillations and the 5th UK Calcium Signalling Conference, a Biochemical Society Focused Meeting held at University of Liverpool, 1–2 May 2003