A bending fluctuation-based mechanism for particle detection by ciliated structures

Thomazo, Jean-Baptiste; Révérend, Benjamin Le; Pontani, Léa-Lætitia; Prevost, Alexis; Wandersman, Élie

doi:10.1073/pnas.2020402118

Cited by 3 publications

(1 citation statement)

References 37 publications

(53 reference statements)

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“…Intermittent and seemingly random fluctuations of order unity compared to the mean value are found in a variety of nonlinear physical systems, such as turbulence in neutral fluids [1][2][3][4] and atmospheric winds [5,6], water resources and hydrology [7,8], complex fluids [9], fission chambers [10], physiology [11][12][13] and biophysics [14] and plasma turbulence, both simulations [15][16][17][18] and measurements from magnetically confined plasmas [19][20][21][22][23][24][25][26][27].…”

Section: Introductionmentioning

confidence: 99%

Reconstruction of intermittent time series as a superposition of pulses

2023

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Fluctuations in a vast range of physical systems can be described as a superposition of uncorrelated pulses with a fixed shape, a process commonly referred to as a (generalized) shot noise or a filtered Poisson process. In this contribution, we present a systematic study of a novel deconvolution method to estimate the arrival times and amplitudes of the pulses from realizations of such processes. The method shows that time-series can be reconstructed for various pulse amplitude and waiting time distributions. Despite a constraint on positive-definite amplitudes, it is shown that negative amplitudes may also be reconstructed by flipping the sign of the time series. The method performs well under moderate amounts of additive noise, both white noise and colored noise having the same correlation function as the process itself. The estimation of pulse shapes from the power spectrum is accurate except for excessively broad waiting time distributions. Although the method assumes constant pulse durations, it performs well under narrowly distributed pulse durations. The most important constraint on the reconstruction is information-loss, which limits the method to intermittent processes. The ratio between the sampling time and the average waiting time between pulses must be about 1/20 or smaller for a well sampled signal. Finally, given the system forcing, the average pulse function may be recovered. This recovery is only weakly constrained by the intermittency of the process.

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Section: Introductionmentioning

confidence: 99%

Reconstruction of intermittent time series as a superposition of pulses

2023

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Feeding Rates in Sessile versus Motile Ciliates are Hydrodynamically Equivalent

Liu,

Man,

Costello

et al. 2024

Preprint

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Motility endows microorganisms with the ability to swim to nutrient-rich environments, but many species are sessile. Existing hydrodynamic arguments in support of either strategy, to swim or to attach and generate feeding currents, are often built on a limited set of experimental or modeling assumptions. Here, to assess the hydrodynamics of these "swim" or "stay" strategies, we propose a comprehensive methodology that combines mechanistic modeling with a survey of published shape and flow data in ciliates. Model predictions and empirical observations show small variations in feeding rates in favor of either motile or sessile cells. Case-specific variations notwithstanding, our overarching analysis shows that flow physics imposes no constraint on the feeding rates that are achievable by the swimming versus sessile strategies – they can both be equally competitive in transporting nutrients and wastes to and from the cell surface within flow regimes typically experienced by ciliates. Our findings help resolve a long-standing dilemma of which strategy is hydrodynamically optimal and explain patterns occurring in natural communities that alternate between free swimming and temporary attachments. Importantly, our findings indicate that the evolutionary pressures that shaped these strategies acted in concert with, not against, flow physics.

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Ciliary mechanosensation – roles of polycystins and mastigonemes

Liu

Zhou

2023

Journal of Cell Science

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Cilia are surface-exposed organelles that provide motility and sensory functions for cells, and it is widely believed that mechanosensation can be mediated through cilia. Polycystin-1 and -2 (PC-1 and PC-2, respectively) are transmembrane proteins that can localize to cilia; however, the molecular mechanisms by which polycystins contribute to mechanosensation are still controversial. Studies detail two prevailing models for the molecular roles of polycystins on cilia; one stresses the mechanosensation capabilities and the other unveils their ligand–receptor nature. The discovery that polycystins interact with mastigonemes, the ‘hair-like’ protrusions of flagella, is a novel finding in identifying the interactors of polycystins in cilia. While the functions of polycystins proposed by both models may coexist in cilia, it is hoped that a precise understanding of the mechanism of action of polycystins can be achieved by uncovering their distribution and interacting factors inside cilia. This will hopefully provide a satisfying answer to the pathogenesis of autosomal dominant polycystic kidney disease (ADPKD), which is caused by mutations in PC-1 and PC-2. In this Review, we discuss the characteristics of polycystins in the context of cilia and summarize the functions of mastigonemes in unicellular ciliates. Finally, we compare flagella and molecular features of PC-2 between unicellular and multicellular organisms, with the aim of providing new insights into the ciliary roles of polycystins in general.

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A bending fluctuation-based mechanism for particle detection by ciliated structures

Cited by 3 publications

References 37 publications

Reconstruction of intermittent time series as a superposition of pulses

Reconstruction of intermittent time series as a superposition of pulses

Feeding Rates in Sessile versus Motile Ciliates are Hydrodynamically Equivalent

Ciliary mechanosensation – roles of polycystins and mastigonemes

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