The cytoskeleton is made of protein-based polymers that are required for proper cell structure and function. These polymer networks serve as machines and tracks to segregate cell components, change cell shape, and act as protein and membrane scaffolds. The septins are a highly conserved component of the cytoskeleton important for processes such as cell division, membrane compartments, and secretion. The septin proteins are widely expressed from fungi to mammals. Septins come together in cells to build higher-order structures such as rings, bars, and fibers. We use a genetically tractable model filamentous fungus called Ashbya gossypii to study septins because its persistent, dynamic and large septin-based assemblies are especially amenable to microscopy and biochemical analysis. The objectives of this project address three key aspects of septin architecture that are presently not understood: 1. Determination of how septin filaments polymerize and link together in living cells; 2. Identification of what factors control where septins are assembled together in cells; and 3. Evaluation of the dynamics of septin filaments. The research employs a combination of novel single molecule and polarized fluorescence imaging, genetic mutant analysis and in vitro biochemical approaches. The experiments in this project tackle a general cellular engineering problem: how to erect persistent, yet dynamic, structures of a constant size at specific locations in the cell. This project will discover basic rules cells use to organize themselves in space to carry out functions of life such as growth and division. Broader Impacts The PI is committed to training undergraduates and graduate students and communicating science in the community. As the course director for undergraduate Cell Biology, the PI will expand on an inquiry-based lab unit developed by her and her research group using Ashbya as a model system. After writing and receiving a grant for "clickers" to use in Biology classes, she has developed a series of questions to change the lecture based cell biology class into an active learning space and will continue to expand and share this tool kit with other faculty in future offerings. The PI has trained seven undergraduates in the lab in the last five years, including two female math and computer science majors and one male computer science major. One undergraduate was awarded an REU in the summer of 2010 to work with the PI at the Marine Biological Lab in Woods Hole. Two Dartmouth undergraduates completed honors theses in the PI's lab this year and both now have had their work published as first authors. She has mentored two female PhD students, one female post-doc and one female technician and has had five female rotation students, two of whom are Latina. The PI speaks about issues facing women in science and balancing science and motherhood at many venues on campus including various sorority faculty dinners, at the Biology undergraduate society, and the undergraduate Women in Science Program. The PI was the keynote speaker at the American Society for Cell Biology Annual Meeting Special Session for undergraduate participants in 2010. The PI has mentored two teacher-scholar post-doctoral fellows to facilitate their development as teachers by co-teaching with them and providing weekly feedback on their teaching. The PI speaks at evening seminars in her community about the importance of basic science research and has spoken to middle school science classrooms about what it is like to be a scientist. Graduate students in the PI's lab regularly teach local high school students and teachers about the principles of light microscopy and the research in our lab. The PI will weave training, mentoring and local community involvement into her research program through the continuation of these described activities.
