Localized calcium signals in early XXXX development.

@entity671 @entity2085 @entity1238 @entity19 @entity141 @entity3392
Activation of the phosphoinositide (PI) pathway has been shown to be involved in the compaction of blastomeres in @entity19 embryos and in @entity2085 formation in @entity1238 and in @entity3392 embryos. Here we investigate @entity141 signals in individual blastomeres of @entity3392 embryos with the goal to better understand the role of PI and @entity141 signaling for early vertebrate embryogenesis. Initial studies showed that the @entity671 (IP3) concentration increases after the 32-cell stage of development, suggesting that IP3-mediated @entity141 signals may be present during the blastula stage. @entity141 signals were measured by identifying individual cells using confocal imaging of a nuclear localized @entity141 indicator. Using this in situ indicator, changes in @entity141 concentration were measured over several hours in each cell of a series of sections through the developing embryo. Transient increases in @entity141 concentration that lasted 20-50 sec ( @entity141 spikes) were first triggered during the 32- to 128-cell stage in cells of the outer embryonic cell layer. These cells develop epithelial characteristics and specialize into the enveloping layer (EVL). No @entity141 activity was observed during the earlier cleavage cycles or in deep blastomeres. @entity141 spikes remained restricted to the EVL until the end of the blastula stage. @entity141 spikes in neighboring EVL cells often occurred in the same short time interval, indicating that small groups of EVL cells can synchronize their activity. When averaged over several cell cycles, @entity141 activity showed an even distribution in the EVL and did not indicate future polarities.
