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.
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.
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).
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.
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. Priess, mex-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).