Establishing the mechanism of the calcium wave at egg activation

Establishing the mechanism of the calcium wave at egg activation

Establishing the mechanism of the calcium wave at egg activation

Supervisor: Dr Tim Weil

Project Summary

Egg activation is a conserved process required to prepare an egg for fertilisation and embryogenesis. In all animals, egg activation is associated with at least one transient increase in cytosolic calcium concentration, a “calcium wave”. The calcium wave is required for resumption of the cell cycle, reconfiguring of the cytoskeleton, cortical granule exocytosis and translation of maternal transcripts.

The focus of this project is to characterise in detail the mechanisms that drive initiation and propagation of calcium waves in eggs at activation. Drosophila is an attractive model of choice for this due to its genetic tractability, imaging options and ease of manipulation. This project builds on past work and exciting new data in the lab showing that osmotic pressure and reorganisation of the cytoskeleton are key factors in initiating the Drosophila calcium wave. Using in vivo advanced imaging of genetically encoded calcium indicators, genetic analysis of key factors, pharmacological disruption and physical micro-manipulation, this project aims to test the role of key candidate genes that have been identified as part of this pathway with biochemistry and forward genetics being further, longer term approaches.

The results from this project are important in understanding the general phenomenon of egg activation, providing a platform for testing conserved mechanisms of egg activation in other animals. This work will likely have implications with to respect to in vitro fertilisation since the cytoplasmic environment of the egg has been shown to be important for increasing the rate of IVF success. Moreover, this project will shed light on how calcium functions as a second messenger. This integrates the project with other research fields which aim to understand essential cellular processes including synaptic transmission, skeletal muscle function and mRNA translational control.

References

York-Andersen AH, Wood BW, Wilby EL, Berry AS, Weil TT. 2021 Osmolarity-regulated swelling initiates egg activation in Drosophila. Open Biol. 11: 210067. https://doi.org/10.1098/rsob.210067

A calcium‐mediated actin redistribution at egg activation in Drosophila York-Andersen A., Hu Q., Wood B., Wolfner., and Weil T.T. Mol Reprod Dev. 2020 Feb; 87(2):293-304. doi: 10.1002/mrd.23311

Calcium and egg activation in Drosophila. Sartain CV, Wolfner MF. Cell Calcium. (2013) Jan;53(1):10-5.