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2013.6.13 Dr. Zhongying ZHAO


Defining regulatory pathways coupling cell division timing and cell fate   differentiation during C. elegans embryogenesis by automated lineaging



Dr. Zhongying ZHAO 


Assistant Professor, Department of Biology, Hong Kong Baptist University

Postdoc (University of Washington)
Ph.D. (Simon Fraser University)
M.Sc. (Beijing Normal University)
B.Sc. (Hons.) (Anhui Normal University)












Time:1:30pm, Jun. 13, 2013


Address:Rm. 101, Old Chemistry Building, east Wing, 1rd floor, CQB



Coordination of division pace among different cells is essential for proper formation of various tissues and organs during animal development. Failure in the coordination frequently leads to tumorous growth or abnormal cell death. How cell division paces are regulated to accommodate cell fate differentiation remains poorly understood. C. elegans embryogenesis provides a unique opportunity to address the issue due to its invariant development. To identify the regulatory proteins coupling cell division and fate determination, we performed a high-content screening of defects in embryonic cell lineage and cell fate differentiation after perturbation of approximate 400 C. elegans genes using automated lineaging. We prioritized the gene list based on their conservation across species and potential defects during embryogenesis after loss of function. We inactivated each of the 400 genes through RNA interference (RNAi) and took three dimensional (3D) time-lapse movies of C. elegans embryogenesis every minute continuously for six hours. The imaged animal carries both a lineaging and a tissue marker, allowing us to simultaneously trace cell divisions and cell fate differentiation for every minute of embryogenesis. We next used the images as input and traced the cell divisions and quantified marker gene expression from zygote to around 350-cell stage for every perturbed embryo by automated lineaging analysis. Preliminary analysis of cell division and/or expression phenotypes have not only confirmed the roles of genes with known function, but also helped assign functions to genes with unknown function. Our dataset provide quantitative and dynamic information on gene functions both at molecular and cellular levels, allowing for inference of gene regulatory pathway coupling cell division pace and fate differentiation. Given the conservation of the prioritized gene, knowledge of their function are likely to have direct relevance to human biology. Challenges on inference of gene network coupling cell division and cell fate determination based on our accumulated data will be discussed.

Host:Professor Chao Tang