April 21, 2023, ESB 2001

One of the central problems in understanding the origins of cell geometry is how cells build structures of defined size. We are using eukaryotic flagella as a model system in which to investigate the mechanism by which a cell can measure and adjust the size of organelles. We have found that flagella are dynamic structures, in which assembly and disassembly need to be balanced to maintain a defined length. Measurements indicate that a kinesin-based transport process involved in flagellar assembly is regulated by length, such that the transport rate is proportional to 1/L. This result indicates that the cell has a way of measuring length in order to control transport. Using a combination of quantitative imaging, computational modeling, genetic screens, and time-series analysis, we are testing potential models for length sensing. We currently favor a model in which the key length dependent process is the diffusive return of kinesin motors from the flagellar tip to the cell body.