..., preparing the metaphase II (MII)-arrested egg for fertilization. Upon sperm-egg fusion, Ca 2+ release from IP 3 -sensitive endoplasmic reticulum stores results in cytoplasmic Ca 2+ oscillations that drive egg activation and initiate early embryo development. Premature Ca 2+ release can cause parthenogenetic...

.... Unexpectedly, maternal zygotic (MZ) dchs1b mutants show defects in the earliest developmental stage, egg activation, including abnormal cortical granule exocytosis (CGE), cytoplasmic segregation, cleavages and maternal mRNA translocation, in transcriptionally quiescent embryos. Later, MZ dchs1b mutants exhibit...

..., the closest living invertebrate group to the vertebrates, we have identified a new signalling pathway for cell cycle resumption in which CaMKII plays no part. Instead, we find that the Ca 2+ -activated phosphatase calcineurin (CN) is required for egg activation. Moreover, we demonstrate that parthenogenetic...

...Wenyan Mei; Karen W. Lee; Florence L. Marlow; Andrew L. Miller; Mary C. Mullins Egg activation is an important cellular event required to prevent polyspermy and initiate development of the zygote. Egg activation in all animals examined is elicited by a rise in free Ca 2+ in the egg cytosol...

... by a non-degradable cyclin B did not prevent cortical granule exocytosis during egg activation( Murray et al., 1989 ). Although mouse oocytes can be parthenogenetically activated to undergo degranulation without cell cycle resumption( Ducibella et al., 2002 ),another study indicated that chromosome...

...+ transients and egg activation has not been found. We identify a novel, sperm-specific phospholipase C, PLCζ, that triggers Ca 2+ oscillations in mouse eggs indistinguishable from those at fertilisation. PLCζ removal from sperm extracts abolishes Ca 2+ release in eggs. Moreover, the PLCζ content of a single...

...Ken-ichi Sato; Tetsushi Iwasaki; Keiko Ogawa; Masako Konishi; Alexander A. Tokmakov; Yasuo Fukami Protein-tyrosine phosphorylation plays an important role in egg activation signaling at fertilization. We show that in Xenopus , fertilization stimulates a rapid and transient tyrosine phosphorylation...

... from the sperm may be a regulator, directly or indirectly, of a Src family kinase in the egg. * Author for correspondence (e-mail: [email protected] ) 22 05 2000 10 07 2000 © 2000 by Company of Biologists 2000 Fertilization Calcium Egg activation Phospholipase Cγ...

... is required either during spermiogenesis or for subsequent sperm functions during egg activation and early zygotic development. To determine the role of the sperm nucleus in these processes, we analyzed two C. elegans mutants whose spermatids lack DNA. Here we show that these anucleate sperm not only...

... was obtained with extracts from mock-transfected COS cells. Similar results were obtained by microinjection of in vitro synthesized tr-kit mRNA into metaphase II-arrested oocytes. Tr-kit-induced parthenogenetic egg activation was completely inhibited by oocyte preincubation with the Ca 2+ -chelating agent...

... localization developed by metaphase I. The role of the ryanodine receptor in mouse egg activation was examined by deter- mining the effects of microinjected ryanodine or cyclic ADP ribose on endpoints of egg activation in either unin- seminated or inseminated eggs. Ryanodine induced the conversion of the zona...

... activation was examined in the present study by determining the effects of microinjected monoclonal antibody (mAb) 18A10, which binds to the IP 3 receptor and inhibits IP 3 -induced Ca 2+ release, on endpoints of egg activation following insemination. The antibody inhibited in a concentration-dependent...

...)ethane-N,N,N′,N′-tetraacetic acid)) at concentrations sufficient to block any global fertilization-associated Ca2+ cyt elevation did not inhibit egg activation (monitored as exocytosis of cell wall) or subsequent development. However, egg activation could be inhibited with higher buffer concentrations...

... by Company of Biologists 1992 egg activation intracellular changes electrostimulation fertilization pig calcium oscillation At fertilization the sperm not only delivers its DNA to the egg to restore diploidy, but also activates the egg and launches it on a path leading to DNA synthesis...

... ,). Recently, it has been proposed that protein kinase C (PKC) is an integral component of the Xenopus fertilization pathway (Bement and Capeo, J. Cell Biol . 108, 885-892, 1989). Indeed, activators of PKC trigger cortical granule exocytosis and cortical contraction, two events of egg activation, without...