A unified model for the dynamics of ATP-independent ultrafast contraction

Floyd, Carlos; Molines, Arthur T.; Lei, Xiangting; Honts, Jerry E.; Chang, Fred; Elting, Mary Williard; Vaikuntanathan, Suriyanarayanan; Dinner, Aaron R.; Bhamla, M. Saad

doi:10.1101/2022.10.14.512304

Cited by 2 publications

(2 citation statements)

References 91 publications

(151 reference statements)

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“…For this microscopic nematode (thinner than a human hair), what kind of ‘latch’ holds this α -shape spring to-gether for a quick microsecond release? Latches, despite their ubiquity in man-made systems, have been relatively understudied in biology [16, 23, 26]. In the case of EPNs, it has been hypothesized (but not proven) that a water droplet acts as a liquid latch to hold the ventral-ventral contact of the EPNs α -shaped spring [10] (Fig.…”

Section: A Cylindrical Shape Motif Forms Lifementioning

confidence: 99%

Reversible kink instability drives ultrafast jumping in nematodes and soft robots

Kumar,

Tiwari,

Ortega-Jimenez

et al. 2024

Preprint

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Entomopathogenic nematodes (EPNs) exhibit a bending-elastic instability, or kink, before becoming airborne, a feature hypothesized but not proven to enhance jumping performance. Here, we provide the evidence that this kink is crucial for improving launch performance. We demonstrate that EPNs actively modulate their aspect ratio, forming a liquid-latched closed loop over a slow timescaleO(1 s), then rapidly open itO(10 µs), achieving heights of 20 body lengths (BL) and generating ∼ 104W/Kg of power. Using jumping nematodes, a bio-inspired Soft Jumping Model (SoftJM), and computational simulations, we explore the mechanisms and implications of this kink. EPNs control their takeoff direction by adjusting their head position and center of mass, a mechanism verified through phase maps of jump directions in simulations and SoftJM experiments. Our findings reveal that the reversible kink instability at the point of highest curvature on the ventral side enhances energy storage using the nematode’s limited muscular force. We investigated the impact of aspect ratio on kink instability and jumping performance using SoftJM, and quantified EPN cuticle stiffness with AFM, comparing it withC. elegans. This led to a stiffness-modified SoftJM design with a carbon fiber backbone, achieving jumps of ∼25 BL. Our study reveals how harnessing kink instabilities, a typical failure mode, enables bidirectional jumps in soft robots on complex substrates like sand, offering a novel approach for designing limbless robots for controlled jumping, locomotion, and even planetary exploration.

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Section: A Cylindrical Shape Motif Forms Lifementioning

confidence: 99%

Reversible kink instability drives ultrafast jumping in nematodes and soft robots

Kumar,

Tiwari,

Ortega-Jimenez

et al. 2024

Preprint

View full text Add to dashboard Cite

show abstract

“…All study data are included in the article and/or supporting information . Code and data used for the results in this paper can be found at https://github.com/bhamla-lab/myonememodelPNAS2023 ( 84 ).…”

Section: Data Materials and Software Availabilitymentioning

confidence: 99%

A unified model for the dynamics of ATP-independent ultrafast contraction

Floyd

Molines

Lei

et al. 2023

Proc. Natl. Acad. Sci. U.S.A.

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In nature, several ciliated protists possess the remarkable ability to execute ultrafast motions using protein assemblies called myonemes, which contract in response to Ca 2+ ions. Existing theories, such as actomyosin contractility and macroscopic biomechanical latches, do not adequately describe these systems, necessitating development of models to understand their mechanisms. In this study, we image and quantitatively analyze the contractile kinematics observed in two ciliated protists ( Vorticella sp. and Spirostomum sp.), and, based on the mechanochemistry of these organisms, we propose a minimal mathematical model that reproduces our observations as well as those published previously. Analyzing the model reveals three distinct dynamic regimes, differentiated by the rate of chemical driving and the importance of inertia. We characterize their unique scaling behaviors and kinematic signatures. Besides providing insights into Ca 2+ -powered myoneme contraction in protists, our work may also inform the rational design of ultrafast bioengineered systems such as active synthetic cells.

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A unified model for the dynamics of ATP-independent ultrafast contraction

Cited by 2 publications

References 91 publications

Reversible kink instability drives ultrafast jumping in nematodes and soft robots

Reversible kink instability drives ultrafast jumping in nematodes and soft robots

A unified model for the dynamics of ATP-independent ultrafast contraction

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