Viscous Loading Regulates the Flagellar Energetics of Human and Bull Sperm

Yazdan Parast, Farin; Veeraragavan, Shibani; Gaikwad, Avinash S.; Powar, Sushant; Prabhakar, Ranganathan; O'Bryan, Moira K.; Nosrati, Reza

doi:10.1002/smtd.202300928

Cited by 2 publications

(1 citation statement)

References 103 publications

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“…The analysis above suggests that it is possible to exploit measurements of viscosities at which 2D-3D transitions in beat patterns to extract quantitative estimates of internal forcing. Recently, a microfluidic device was used to systematically study the effect of varying viscosity on the flagellar waveforms of single sperm cells 57 . Transitional viscosities obtained in such devices could be combined with independent measurements of the bending stiffness and compared with results from detailed simulations that account for features that have been neglected here ( e .…”

Section: Discussionmentioning

confidence: 99%

Elastohydrodynamic mechanisms govern beat pattern transitions in eukaryotic flagella

Veeraragavan,

Parast,

Nosrati

et al. 2024

Preprint

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Eukaryotic cilia and flagella exhibit complex beating patterns that vary depending on environmental conditions such as fluid viscosity. These transitions are thought to arise from changes in the internal forcing provided by the axoneme, although the mechanism remains unclear. We demonstrate with simulations of Kirchhoff rods driven internally by active bending moments that a single elastohydrodynamic instability universally explains transitions between planar, quasiplanar, helical, and complex beating patterns due to changes in either the internal forcing, flagellar stiffness and length, or due to changes in the hydrodynamic resistance, either due to the viscosity of the ambient medium or the presence of a plane wall. The beat patterns and transitions are comparable to those exhibited by bull sperm and sea urchin sperm in our experiments and elsewhere. Our results point to a general model that can describe flagellar and ciliary beating across all species. We further show that internal dynein forces can be estimated by comparing simulation results with experimental observations of transitional viscosities. This can potentially lead to diagnostic assays to measure the health of sperm cells based on their beating pattern.

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Section: Discussionmentioning

confidence: 99%

Elastohydrodynamic mechanisms govern beat pattern transitions in eukaryotic flagella

Veeraragavan,

Parast,

Nosrati

et al. 2024

Preprint

Self Cite

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Exploring sperm cell rheotaxis in microfluidic channel: the role of flow and viscosity

Puri,

Jacob,

Hemadri

et al. 2024

Phys. Biol.

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Rheotaxis is a fundamental mechanism of sperm cells that guides them in navigating towards the oocyte. The present study investigates the phenomenon of sperm rheotaxis in Newtonian and non-Newtonian fluid media, which for the first time explores a viscosity range equivalent to that of the oviductal fluid of the female reproductive tract in rectilinear microfluidic channels. Three parameters, the progressive velocity while performing rheotaxis, the radius of rotation during rheotaxis, and the percentage of rheotactic sperm cells in the bulk and near-wall regions of the microfluidic channel, were measured. Numerical simulations of the flow were conducted to estimate the shear rate, flow velocity, and the drag force acting on the sperm head at specific locations where the sperms undergo rheotaxis. Increasing the flow velocity resulted in a change in the position of rheotactic sperm from the bulk center to the near wall region, an increase and subsequent decrease in the sperm’s upstream progressive velocity, and a decrease in the radius of rotation. We observed that with an increase in viscosity, rheotactic sperms migrate to the near wall regions at lower flow rates, the upstream progressive velocity of the sperm decreases for Newtonian and increases for non-Newtonian media, and the radius of rotation increases for Newtonian and decreases for non-Newtonian media. These results quantify the effects of fluid properties such as viscosity and flow rate on sperm rheotaxis and navigation, thereby paving the way for manipulating sperm behavior in microfluidic devices, potentially leading to advancements in assisted reproduction techniques.

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Viscous Loading Regulates the Flagellar Energetics of Human and Bull Sperm

Cited by 2 publications

References 103 publications

Elastohydrodynamic mechanisms govern beat pattern transitions in eukaryotic flagella

Elastohydrodynamic mechanisms govern beat pattern transitions in eukaryotic flagella

Exploring sperm cell rheotaxis in microfluidic channel: the role of flow and viscosity

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