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Bimodal rheotactic behavior reflects flagellar beat asymmetry in human sperm cells
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Bukatin, Anton, Kukhtevich, Igor, Stoop, Norbert, Dunkel, Jörn and Kantsler, Vasily (2015) Bimodal rheotactic behavior reflects flagellar beat asymmetry in human sperm cells. Proceedings of the National Academy of Sciences of the United States of America, 112 (52). pp. 15904-15909. doi:10.1073/pnas.1515159112 ISSN 0027-8424.
An open access version can be found in:
Official URL: http://dx.doi.org/10.1073/pnas.1515159112
Abstract
Rheotaxis, the directed response to fluid velocity gradients, has been shown to facilitate stable upstream swimming of mammalian sperm cells along solid surfaces, suggesting a robust physical mechanism for long-distance navigation during fertilization. However, the dynamics by which a human sperm orients itself relative to an ambient flow is poorly understood. Here, we combine microfluidic experiments with mathematical modeling and 3D flagellar beat reconstruction to quantify the response of individual sperm cells in time-varying flow fields. Single-cell tracking reveals two kinematically distinct swimming states that entail opposite turning behaviors under flow reversal. We constrain an effective 2D model for the turning dynamics through systematic large-scale parameter scans, and find good quantitative agreement with experiments at different shear rates and viscosities. Using a 3D reconstruction algorithm to identify the flagellar beat patterns causing left or right turning, we present comprehensive 3D data demonstrating the rolling dynamics of freely swimming sperm cells around their longitudinal axis. Contrary to current beliefs, this 3D analysis uncovers ambidextrous flagellar waveforms and shows that the cell’s turning direction is not defined by the rolling direction. Instead, the different rheotactic turning behaviors are linked to a broken mirror symmetry in the midpiece section, likely arising from a buckling instability. These results challenge current theoretical models of sperm locomotion.
Item Type: | Journal Article | ||||||
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Subjects: | Q Science > QC Physics Q Science > QH Natural history > QH301 Biology |
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Divisions: | Faculty of Science, Engineering and Medicine > Science > Physics | ||||||
Journal or Publication Title: | Proceedings of the National Academy of Sciences of the United States of America | ||||||
Publisher: | National Academy of Sciences | ||||||
ISSN: | 0027-8424 | ||||||
Official Date: | 29 December 2015 | ||||||
Dates: |
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Volume: | 112 | ||||||
Number: | 52 | ||||||
Page Range: | pp. 15904-15909 | ||||||
DOI: | 10.1073/pnas.1515159112 | ||||||
Status: | Peer Reviewed | ||||||
Publication Status: | Published | ||||||
Access rights to Published version: | Restricted or Subscription Access | ||||||
Open Access Version: |
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