Author ORCID Identifier
Sizhe Cheng: 0009-0007-5623-4112
Raveen Armstrong: 0000-0002-0641-3725
Becca Thomases: 0000-0001-8502-8915
Shuang Zhou: 0000-0002-6442-6866
Document Type
Article
Publication Date
6-30-2026
Publication Title
PNAS: Applied Physical Sciences
Abstract
Significance:
Trypanosoma brucei is a single-cell parasite causing sleeping sickness across 37 sub-Saharan countries, threatening ~60 million people. Revealing its locomotion mechanism is critical to understand its lifecycle in fly vectors and mammalian hosts; however, progress has been hindered by the rapid and complex cell deformation driven by a laterally attached flagellum. By tracking the 3D motion of fluorescent particles attached to cell surface, we demonstrate that tip-to-base helical waves generate self-propulsion like an active corkscrew, with reactive torque inducing counterrotation of the cell body. These findings inform future investigations of the underlying biomechanics, suggest potential routes for therapeutic intervention, and inspire biomimetic microrobotic designs. The defocused particle tracking technique is broadly applicable for deciphering the dynamics of other complex microswimmers.
Abstract:
In the pathogenic parasite Trypanosoma brucei, a laterally attached flagellum drives rapid deformation of the complex cell body, producing puzzling dynamics. High-speed defocusing imaging reveals that surface points trace flower-like patterns in transverse planes. The petals arise from clockwise flagellar beating, which generates a right-handed helical wave propagating from the anterior tip along the body, advancing the cell like a twisted corkscrew. The central lobes result from slower counterclockwise body rotation required to balance the active torque. The bent cell shape underneath the flagellum superimposes these two chiral motions at different radial distances, producing the observed patterns. Three-dimensional hydrodynamic simulations using the method of regularized Stokeslets reproduce these dynamics and show that bent cell shape enhances swimming, suggesting an adaptive advantage of T. brucei’s morphology.
Volume
123
Issue
27
First Page
e2536746123
Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 International License.
Rights
Licensed to Smith College and distributed CC-BY 4.0 under the Smith College Faculty Open Access Policy.
Version
Author's Accepted Manuscript
Recommended Citation
Cheng, Sizhe; Das, Devadyouti; Barchuk, Mykhaylo; Armstrong, Raveen; Klingbeil, Michele M.; Thomases, Becca; and Zhou, Shuang, "Corkscrew Motion of Trypanosoma brucei is Driven by Helical Beating of the Flagellum and Facilitated by its Bent Shape" (2026). Mathematics Sciences: Faculty Publications, Smith College, Northampton, MA.
https://scholarworks.smith.edu/mth_facpubs/216