4:00 p.m., Monday (Jan. 20th)
Theoretical Biology and Biophysics Group
Los Alamos National Laboratory
Chirality Inversions Propagating on Bacterial Flagella
Many experimental investigations have shown that bacterial
flagella (the long, whip-like structures that provide thrust
during swimming) take on a variety of helical forms under
differing mechanical and chemical conditions. During the
1980s a series of experiments examined the response of a
single, detached flagellum to simple fluid stresses. In
particular, when a flagellum is clamped at one end and
placed in an axial external flow, it is observed that
regions of the flagellum transform to the opposite
chirality and travel as pulses down the length of the
filament, the process repeating periodically.
We propose a theory for this phenomenon based on a treatment
of the flagellum as an elastic object with multiple stable
configurations. This theory is expressed in terms of coupled
PDEs for the filament shape and twist configuration, and
involves only physical, measurable properties of the flagellum.
We generate simulations that quantitatively reproduce key
features seen in experiment.
Refreshments will be served at 3:45 p.m. in the Faculty Lounge,
Math Annex (Room 1115).