The Kinematics of Explosively Jerky Diatom Motility: A Natural Example of Active Nanofluidics

Sabuncu, Ahmet C.; Gordon, Richard; Richer, Edmond; Manoylov, Kalina M.; Beşkök, Ali

doi:10.1002/9781119526483.ch2

Cited by 4 publications

(4 citation statements)

References 68 publications

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“…Supposing that at t = 0 the bead attached to a stretched EPS fiber (of spring constant k) is released from position x(t = 0) = x 0 (due to breakage of a link with a second fiber), the resulting bead motion in the low Reynolds number regime is approximated by: x(t) = x 0 exp(−t/τ ), where τ = γ/k = 3 × 10 −4 s, using the values γ = 1.2 × 10 −8 N s m −1 , and k = 0.04 pN nm −1 . This time scale is consistent with the sudden diatom motions (translation and rotation) registered in highspeed video-microscopy (821 fps) [15]. Similarly, in our work we observed significant bead translocation from one frame to the next (at 30 fps) as illustrated in figure 3, yielding a bead speed (at least 20 μm s −1 ) that is significantly higher than the speed values of smooth particle streaming.…”

Section: Discussionsupporting

confidence: 91%

“…This motion implies minimum bead speed and acceleration of 21 μm s −1 and 630 μm s −2 , respectively. These values are consistent with highspeed imaging and tracking of diatom jerky motion during gliding [15]. Examples of speed vs time records for different beads (figures 3(A) and (B)) show alternation of smooth and jerky motions.…”

Section: Resultssupporting

confidence: 83%

“…Occasionally, large speeds (>6 μm s −1 ) were present during brief time periods (sub-second). These events are consistent with the so-called 'jerky' motions characteristic of diatom gliding and particle streaming [15]. One of these such events is presented in figure 3(A).…”

Section: Resultssupporting

confidence: 77%

“…By analyzing particle motions relative to the diatom body, Edgar [13] found distinctive short-time events of large velocity and acceleration ('jerky' motion), and that beads often presented motion in direction opposed and with different velocity compared to the diatom. It has been proposed that jerky motion is due to elastic snapping [15], where the storing and release of mechanical energy in the mucilage fibers that drive diatom gliding originates unbalanced mechanical force, causing explosive bead motion in particle streaming. In this work, by directly testing the mechanics of particle streaming and EPS fibers, we provide a quantitative basis for this proposal.…”

Section: Introductionmentioning

confidence: 99%

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Mechanical testing of particle streaming and intact extracellular mucilage nanofibers reveal a role of elastic force in diatom motility

Gutiérrez–Medina¹,

Maldonado²,

García‐Meza³

2022

Phys. Biol.

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Diatoms are unicellular microalgae with a rigid cell wall, able to glide on surfaces by releasing nanopolymeric fibers through central slits known as raphes. Here we consider the model Nitszchia communis to perform quantitative studies on two complementary aspects involved in diatom gliding. Using video microscopy and automated image analysis, we measure the motion of test beads as they are pulled by extracellular polymeric substances (EPS) fibers at the diatom raphe (particle streaming). A multimodal distribution of particle speed is found, evidencing the appearance of short-time events of high speed and acceleration (known as jerky motion) and suggesting that different mechanisms contribute to set diatom velocity during gliding. Furthermore, we use optical tweezers to obtain force-extension records for extracellular diatom nanofibers; records are well described by the worm-like chain model of polymer elasticity. In contrast to previous studies based on application of denaturing force (in the nN regime), application of low force (up to 6 pN) and using enable us to obtain the persistence length of intact fibers. From these measurements, mechanical parameters of EPS fibers such as radius and elastic constant are estimated. Furthermore, by modeling particle streaming as a spring in parallel with a dashpot, we show that the time involved in the release of mechanical energy after fiber detachment from beads (elastic snapping) agrees with our observations of jerky motion. We conclude that the smooth and jerky motions displayed by gliding diatoms correspond to molecular motors and elastic snapping, respectively, thus providing quantitative elements that incorporate to current models of the mechanics behind diatom locomotion.

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Section: Discussionsupporting

confidence: 91%

Section: Resultssupporting

confidence: 83%

Section: Resultssupporting

confidence: 77%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Mechanical testing of particle streaming and intact extracellular mucilage nanofibers reveal a role of elastic force in diatom motility

Gutiérrez–Medina¹,

Maldonado²,

García‐Meza³

2022

Phys. Biol.

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Raphe

Singh¹,

Katyal²,

Gordon

2023

The Mathematical Biology of Diatoms

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The Photoprotective Behavior of a Motile Benthic Diatom as Elucidated from the Interplay Between Cell Motility and Physiological Responses to a Light Microgradient Using a Novel Experimental Setup

Morelle,

Bastos,

Frankenbach

et al. 2024

Microb Ecol

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It has long been hypothesized that benthic motile pennate diatoms use phototaxis to optimize photosynthesis and minimize photoinhibitory damage by adjusting their position within vertical light gradients in coastal benthic sediments. However, experimental evidence to test this hypothesis remains inconclusive, mainly due to methodological difficulties in studying cell behavior and photosynthesis over realistic spatial microscale gradients of irradiance and cell position. In this study, a novel experimental approach was developed and used to test the hypothesis of photosynthesis optimization through motility, based on the combination of single-cell in vivo chlorophyll fluorometry and microfluidic chips. The approach allows the concurrent study of behavior and photosynthetic activity of individual cells of the epipelic diatom species Craspedostauros britannicus exposed to a light microgradient of realistic dimensions, simulating the irradiance and distance scales of light microgradients in benthic sediments. Following exposure to light, (i) cells explored their light environment before initiating light-directed motility; (ii) cells used motility to lower their light dose, when exposed to the highest light intensities; and (iii) motility was combined with reversible non-photochemical quenching, to allow cells to avoid photoinhibition. The results of this proof-of-concept study not only strongly support the photoprotective nature of photobehavior in the studied species but also revealed considerable variability in how individual cells reacted to a light microgradient. The experimental setup can be readily applied to study motility and photosynthetic light responses of other diatom species or natural assemblages, as well as other photoautotrophic motile microorganisms, broadening the toolset for experimental microbial ecology research.

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The Kinematics of Explosively Jerky Diatom Motility: A Natural Example of Active Nanofluidics

Cited by 4 publications

References 68 publications

Mechanical testing of particle streaming and intact extracellular mucilage nanofibers reveal a role of elastic force in diatom motility

Mechanical testing of particle streaming and intact extracellular mucilage nanofibers reveal a role of elastic force in diatom motility

Raphe

The Photoprotective Behavior of a Motile Benthic Diatom as Elucidated from the Interplay Between Cell Motility and Physiological Responses to a Light Microgradient Using a Novel Experimental Setup

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