Mathematical Biology Program

University of Utah
Department of Mathematics

Mathematical Biology Program


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Mathematical Biology seminar

Greg Huber
U Mass
"Chirality transformations on bacterial flagella"
March 5 (Friday)
3:05pm in LCB 215

Chemotaxis in many bacterial species is made possible by the remarkable dynamics of their multiple, rotating, helical flagella. They bundle and de-bundle as their rotary motors episodically change rotational direction. When the flagella are bundled, the bacterium moves linearly, but the dissolution of the bundle leads to a tumbling event that effectively randomizes the cell's orientation. The motor reversal that initiates the tumbling not only torques the flagella oppositely, but also reverse the chirality of the filament, turning a left-handed helix into a right-handed helix. Hotani has performed careful experiments on helical flagella in external flows and he observed that regions within the filament periodically flip to the opposite chirality, and that those domains propagate stably downstream. I'll present a dynamical model for this phenomenon based on the existence of two competing locally stable states of opposite chirality whose interaction with the flow is through the torque they produce. The model displays a number of the key features seen in the experiments.

For more information contact J. Keener, 1-6089