Ca2+ oscillations at fertilization in mammals

Abstract

The mouse egg provided the first direct measurement of Ca(2+) oscillations in any cell type. These sperm-induced Ca(2+) oscillations occur at a relatively low frequency, and can be detected up to 18-20 h after sperm-egg fusion. The Ca(2+) 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 Ca(2+) signalling at fertilization is reflected in the role of the Ca(2+) transients in stimulating exit from metaphase arrest. Recent developments have started to shed light on the mechanism initiating Ca(2+) oscillations at fertilization, on how the frequency of the oscillations is set, and on what determines their temporal pattern.

The cell cycle: a new entry in the field of Ca2+ signaling

“…In mouse oocytes, instead, two series of InsP 3 -dependent Ca 2+ oscillations from metaphase II to interphase of the first cell cycle stimulate exit from metaphase arrest. The Ca 2+ signals terminate following the formation of nuclei in the twocell-stage embryo, and inhibition of pronuclei formation leads to persistent Ca 2+ oscillations, indicating that the cessation of Ca 2+ transients is linked to the sequestration of the newly forming pronuclei [88]. Starfish oocytes have also contributed to our understanding of oocyte maturation [89].…”

Aide à l’activation ovocytaire

“…Néanmoins, il existe une différence notable de la signalisation calcique induite par ce procédé comparée au processus physiologique. En effet, l'ionophore calcique provoque une entrée massive de calcium et une augmentation en plateau de la concentration en calcium intracellulaire dans l'ovocyte jusqu'au rinçage de la molécule, contrairement au processus physiologique qui implique l'induction d'oscillations calciques pouvant perdurer après l'expulsion du deuxième globule polaire [24]. Ce signal, induit artificiellement, diffère donc qualitativement de celui observé lors d'une fécondation par FIV (fécondation in vitro) ou ICSI (intracytoplasmic sperm injection).…”

Tachyphylaxis to the inhibitory effect of L-type channel blockers on ACh-induced [Ca2+]i oscillations in porcine tracheal myocytes

“…Agonist-induced oscillations in free intracellular calcium concentration ([Ca 2+ ] i ) have been observed in a wide range of cell types, and have been linked to a variety of different cellular functions [1][2][3][4][5][6]. In tracheal smooth muscle cells (TSMC), the frequency and amplitude of [Ca 2+ ] i oscillations induced by acetylcholine (ACh) was shown to correspond with the development of contractile force in the muscle strip [1,7].…”