Two tales from small-scale motility
Navish Wadhwa, Post-doctoral Fellow
In this talk I will present my work on the hydrodynamics of planktonic motility and some recent work on the self-assembly of the bacterial flagellar motor components. Small planktonic organisms live a difficult life in open waters, having to continuously scan large amounts of water for food and mates, and hide from predators at the same time. In the absence of vision at these small scales, chemical and mechanical cues are highly important, creating an evolutionary pressure to minimize any disturbances generated during feeding and locomotion. In the first part of this talk, I will present our examination of these processes. We measured flow disturbances created during swimming of a wide range of zooplankton and found that the decay of hydrodynamic disturbance relates to the swimming mode. Breast stroke, a common swimming mode in plankton, results in “quiet” swimming, in which flow velocity decays with distance cubed. In the second part of the talk, I will discuss how the flagellar motor of bacteria can dynamically re-build itself in response to changing environments. I will present our recent experiments to measure the response of the motor to changes in viscous load. When the load is altered, the motor responds by recruiting or releasing torque-generating stator units, to match output with demand.
Navish Wadhwa obtained his PhD in Physics at the Technical University of Denmark, where he studied the hydrodynamics of swimming in zooplankton. In 2016, he switched fields from hydrodynamics to molecular biophysics, and joined Harvard University as a postdoc in the lab of Howard Berg, where he now studies the mechanobiology of the bacterial flagellar motor.