Research

credit: B. Draper

I recently completed a stint studying epigenetics at Fred Hutchinson Cancer Research Center. I did gene editing with CRISPR/Cas9 in the fruit fly Drosophila, and learned how to read those crazy genomics graphs – learn more about the work in the lab here (Steve Henikoff).

Here below I describe my graduate work in developmental biology.  I completed this research years ago, but the images are so cool I still feel like sharing them!

My work examined this basic question: how does a single cell, the egg, give rise to a complex organism?  The answer to this question is still wide open – but my colleagues and I helped uncover a part of the story. We studied this question in the diminutive roundworm C. elegans–shown above in black and white, from the two-cell to the larval stage.  We identified two proteins, PIE-1 and MEX-5, that tell the early embryo which end is which–anterior or posterior.  The following images show PIE-1 and MEX-5 under the microscope, shortly after fertilization of the egg. The proteins are lit up with fluorescent molecules that attach to them.

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PIE-1 (green) appears in the posterior and MEX-5 (purple) appears in the anterior of the one-cell stage embryo.  PIE-1 helps tell posterior cells what structures to turn into, such the cells that give rise to sperm and egg.  MEX-5  helps tell anterior cells what to become–it operates by shutting off PIE-1 and other proteins.

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This image shows another protein, PAR-2 (orange), that localizes at the perimeter of the embryo, on the posterior side. PAR-2 helps set up where PIE-1 and MEX-5  appear.  The final image shows all three proteins together, PAR-2 (orange), PIE-1 (green) and MEX-5 (red).

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I studied these processes as part of my Ph.D. work at the University of Washington Department of Zoology and Fred Hutchinson Cancer Research Center in Seattle. I worked in the lab of James Priess, in collaboration with Craig Mello, Rueyling Lin and others. You can read more in the following mini-review in Cell, and in my publications in peer-reviewed journals.

Minireview:

Ken Kemphues, PARsing embryonic polarity. Cell 101, 345-348, pp. 345-348 (2000).

Publications in peer-reviewed journals:

 

Ka Ming Pang, Takao Ishidate, Kuniaki Nakamura, Masaki Shirayama, Chris Trzepacz, Charlotte Schubert, James R. Priess and Craig C. Mello, The minibrain kinase homolog, mbk-2, is required for spindle positioning and asymmetric cell division in early C. elegans embryos. Developmental Biology 265, pp. 127-139 (2004).

Charlotte Schubert, Rueyling Lin, Corry J. de Vries, Ronald H. Plasterk, and James R. Priessmex-5 and mex-6 function to establish soma/germline asymmetry in early C. elegans embryos. Molecular Cell 5, pp. 671-682 (2000).

Christina Tenenhaus, Charlotte Schubert, Geraldine Seydoux,  Genetic requirements for transcriptional silencing and PIE-1 localization in the embryonic  germ lineage of C. elegans, Developmental Biology 200. pp. 212-224 (1999).

Craig. C. Mello, Charlotte Schubert, Bruce Draper, Wei Zhang, Robert Lobel and James R. Priess, The PIE-1 protein and germline specification in C. elegans embryos, Nature,  382.  pp. 710 – 712 (1996).