Part III: Gurken Gradient and Follicle Cell Response
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How do complex multicellular organisms develop from single celled eggs with a single nucleus? We study this question in the fruitfly, Drosophila. In these insects, as in many other organisms, the major body plan is predetermined during oogenesis, or egg development. In the first part of the lecture, I will give an introduction to oogenesis in Drosophila, and the techniques we use to find genes that are responsible for determining the major axes of the egg and embryo. Interestingly, our analysis revealed that this process requires cell to cell communication between the oocyte and the surrounding follicle cells. It involves a signaling molecule, Gurken, which provides a localized signal from the oocyte to the follicle cells and ultimately sets up both the anterior-posterior as well as the dorso-ventral axis of the egg.
In the second part of the lecture I will introduce our ongoing efforts to understand axis formation in Drosophila oogenesis at a molecular level. In the first part of the lecture, I introduced the localized signaling molecule, Gurken. The RNA that encodes Gurken accumulates in a very restricted area of the oocyte. This localization signals spatial information to the surrounding follicle cells. I will explain how we use a combination of biochemical techniques and live imaging to unravel the mechanisms that localize this RNA during oocyte development. This work is in progress, and the lecture will provide a snapshot of what we know and what the open questions are.
Part 3: The third part of the lecture focuses on the spatial information that is conveyed by the oocyte to the surrounding follicle cells. I discuss how the spatially restricted activation of the EGF receptor by the signaling molecule, Gurken, is relayed into a cascade of information that ultimately sets up the dorso-venral axis of the embryo. I explain how we use genetic mosaicism in the follicle epithelium to ask questions about this signaling process. I also summarize results that were obtained in collaboration with my colleague, Stas Shvartsman, where we used a combination of experiments and modelling to determine the shape of the Gurken gradient.
Trudi Schupbach is Professor of Molecular Biology at Princeton University and a Howard Hughes Investigator. She grew up in Switzerland, and did her undergraduate and graduate work at the University of Zurich studying the development of the genital disc and sex determination in the germline of Drosophila. She moved to Princeton as a research associate in 1981, where she began her work on the study of axis formation and cell to cell signaling during Drosophila oogenesis.
She became a member of the tenured faculty at Princeton in 1990, and an Associate Investigator of the Howard Hughes Medical Institute in 1994. She has identified and characterized many genes that act during oogenesis to set up the polarity and pattern of the egg and the surrounding follicle cells. Her most recent work has also uncovered a meiotic checkpoint mechanism that affects patterning in oogenesis.
Dr. Schupbach is a member of the American Academy of Arts and Sciences and of the National Academy of Sciences. She serves as Associate Editor of Genetics and of Advances in Genetics, and she is a member of the Editorial Board of PNAS and Developmental Cell.
She was awarded the Edwin F. Conklin Medal by the Society for Developmental Biology, and she has served as the president of the Genetics Society of America.
- Thomas Kornberg iBioSeminar: Signaling at a Distance: Communicating by Touch
- Ruth Lehmann iBioSeminar: Germ Cell Development in Drosophila
- Michael Levine iBioSeminar: Transcriptional Precision in the Drosophila Embryo
- Roy Parker iBioSeminar: mRNA Localization, Translation and Degradation
- Eric Wieschaus and Christiane Nüsslein-Volhard: Collaborating to Find Developmental Genes
- Eric Wieschaus iBioSeminar: Patterning Development in the Early Drosophila Embryo