Mechanical Engineering Fall Seminar Series: Class 530.803
“The Flagellar Length Control System”
Presented by Professor Wallace Marshall
Department of Biochemistry and Biophysics, UCSF
A fundamental question in cell biology is how cells regulate the size of their organelles. The problem of organelle size control represents a particularly interesting question of biological regulation between the molecular pathways responsible are somehow able to control size on the length scale of millimeters. Do cells “know” how large their organelles are, in order to execute feedback control? We have been investigating this question using eukaryotic flagella (cilia) as a model organelle, chosen because flagellar size can only vary in a single dimension – length. I will present a simple model for length control that can explain all known experimental data, but which requires the cell to be able to tune a protein transport machine as a function of length. I will then discuss possible mechanisms for how this length-dependent control may be achieved, and experiments designed to test them.
Professor Wallace Marshall trained in electrical engineering at SUNY Stony Brook, where he became interested in the mechanisms by which living cells solve engineering problems, a question he has pursued ever since. As a Ph.D. student at UCSF, he analyzed the organization and motion of interphase chromatin using image processing approaches, and then went on to study cell biology as a postdoctoral fellow at Yale University, where he began his work on flagellar length control. After starting his own lab at UCSF, he continued working on flagellar length regulation, but also expanded the research program to include size control systems regulating other organelles, such as mitochondria and vacuoles. His lab employs an integrated combination of live cell microscopy, mathematical modeling, genetics, and high-throughput approaches. He is currently the Director of the Center for Cellular Construction, a new NSF-funded center whose goal is to develop methods for engineering cellular structure.