Geraldine Seydoux (Johns Hopkins / HHMI) 1: From Egg to Worm: How to Create a Body Axis

Part 1: From Egg to Worm: How to Create a Body Axis: In this video, Dr. Seydoux introduces how PAR proteins create a body axis and how her lab discovered that these proteins are regulated by sperm microtubules.

Part 2: How to Polarize the Cytoplasm: In her second video, Dr. Seydoux describes how MEX-5 proteins diffuse across the embryo cytoplasm to create a gradient and influence body axis development.

https://www.ibiology.org/development-...

Talk Overview:
During development, how do embryos distinguish their posterior (tail) versus anterior (head)? Dr. Geraldine Seydoux’s lab uses the small worm C.elegans as a simple model to study this question. In her first video, she introduces how the sperm divides the egg into distinct anterior and posterior domains shortly after fertilization. Her lab discovered that the sperm introduces microtubules that reorganizes the distribution of a network of polarity regulators, called PAR proteins. The PAR proteins segregate into two non-overlapping domains that define the anterior and posterior axis of the worm.

In part two, Seydoux explains how the PAR domains reorganize other proteins in the cytoplasm of the one-cell embryo. MEX-5 is an RNA-binding protein that localizes to the anterior side of the embryo, forming a concentration gradient in the cytoplasm. Excitingly, her lab discovered that the MEX-5 gradient is caused entirely by the difference in diffusion rates between two MEX-5 species! The shift between the two species is controlled by PAR-1-mediated phosphorylation. This simple mechanism explains how a protein can become localized to a particular area of the cell without directed transport.

Speaker Biography:
Dr. Geraldine Seydoux is a Howard Hughes Medical Institute investigator running a developmental biology lab at the Johns Hopkins University School of Medicine where she is currently the Sheldon Professor of Medical Discovery. Her lab focuses on understanding the mechanisms behind the early stages of embryogenesis. She received her BS in Biochemistry from the University of Maine in 1986, and PhD from Princeton University in 1991. Before becoming a professor at Johns Hopkins, she did a postdoctoral fellowship at Carnegie Institute of Washington with Andy Fire. She became an assistant professor at the Johns Hopkins University in 1995 and a earned a full professorship in 2004. She has received multiple scientific awards including a MacArthur Fellowship in 2005. More recently, in 2016, she was elected to the National Academy of Sciences. Learn more about her research here:
http://seydouxlab.mbg.jhmi.edu/