Dr.David Carroll, Ph.D.

My lab is interested in the molecular mechanisms that regulate egg activation at fertilization. Sperm-egg fusion initiates a transient increase in the concentration of cytoplasmic calcium in the egg. This increase is a fundamental process that occurs in the eggs of all the organisms that have been studied (even plants) and it is critical for activating the egg to begin development. Incredibly, the molecular mechanism that links the sperm-egg interaction to the initiation of this calcium increase is only now beginning to be understood.

Our research focuses on the role of a particular enzyme called phospholipase C gamma. PLC-gamma is a member of a larger class of cytoplasmic enzymes called phospholipases. These enzymes function to produce two signaling messenger molecules called diacylglycerol and inositol 1,4,5-trisphosphate from membrane phospholipids. They function in many cell types, including nerves, muscles and immune cells. In eggs, PLC-gamma is the enzyme that is necessary for the calcium release from the endoplasmic reticulum that is needed for egg activation. With colleagues, we have identified two Src tyrosine kinases that interact with PLC-gamma and are also needed at fertilization. This has led to us to propose the following signaling pathway in our model systems (sea urchins, starfish, ascidians, and maybe frogs!).