A Simple Case of Salt Antagonism in Starfish Eggs

Activation by serotonin of starfish eggs expressing the rat serotonin 1c receptor.

Starfish oocytes were injected with mRNA for the serotonin 1c receptor or with rat brain poly A+ mRNA, incubated to allow expression of the membrane protein, then matured to eggs by addition of 1-methyladenine. Applying serotonin to these eggs caused cortical granule exocytosis like that occurring at fertilization. Because the serotonin 1c receptor specifically activates a G-protein, these resu...

Distinct roles for multiple Src family kinases at fertilization.

Egg activation at fertilization requires the release of Ca2+ from the endoplasmic reticulum of the egg. Recent evidence indicates that Src family kinases (SFKs) function in the signaling pathway that initiates this Ca2+ release in the eggs of many deuterostomes. We have identified three SFKs expressed in starfish (Asterina miniata) eggs, designated AmSFK1, AmSFK2 and AmSFK3. Antibodies made aga...

p90Rsk is required for G1 phase arrest in unfertilized starfish eggs.

The cell cycle in oocytes generally arrests at a particular meiotic stage to await fertilization. This arrest occurs at metaphase of meiosis II (meta-II) in frog and mouse, and at G1 phase after completion of meiosis II in starfish. Despite this difference in the arrest phase, both arrests depend on the same Mos-MAPK (mitogen-activated protein kinase) pathway, indicating that the difference rel...

Intracellular Oxidation-reduction Studies v. a Comparison of Intact and Cytolysed Starfish Eggs by the Immersion Method

Calcium Release at Fertilization in Starfish Eggs Is Mediated by Phospholipase Cγ

Although inositol trisphosphate (IP3) functions in releasing Ca2+ in eggs at fertilization, it is not known how fertilization activates the phospholipase C that produces IP3. To distinguish between a role for PLCgamma, which is activated when its two src homology-2 (SH2) domains bind to an activated tyrosine kinase, and PLCbeta, which is activated by a G protein, we injected starfish eggs with ...