Flagellar Kinematics and Swimming of Algal Cells in Viscoelastic Fluids

Qin, Boyang; Gopinath, Arvind; Yang, Jing; Gollub, Jerry P.; Arratia, Paulo E.

doi:10.1038/srep09190

Cited by 114 publications

(142 citation statements)

References 35 publications

Supporting

Mentioning

120

Contrasting

Order By: Relevance

“…Particles less than 2 µm in diameter are imaged with fluorescence microscopy (red, 589 nm) to clearly visualize particles distinct from E. coli (2 µm long). We obtain the particle positions in two dimensions over time using particle tracking methods 38,39 . All experiments are performed at T 0 = 22 • C.…”

Section: Experimental Methodsmentioning

confidence: 99%

See 1 more Smart Citation

Particle diffusion in active fluids is non-monotonic in size

et al. 2016

View full text Add to dashboard Cite

We experimentally investigate the effect of particle size on the motion of passive polystyrene spheres in suspensions of Escherichia coli. Using particles covering a range of sizes from 0.6 to 39 microns, we probe particle dynamics at both short and long time scales. In all cases, the particles exhibit super-diffusive ballistic behavior at short times before eventually transitioning to diffusive behavior. Surprisingly, we find a regime in which larger particles can diffuse faster than smaller particles: the particle long-time effective diffusivity exhibits a peak in particle size, which is a deviation from classical thermal diffusion. We also find that the active contribution to particle diffusion is controlled by a dimensionless parameter, the Péclet number. A minimal model qualitatively explains the existence of the effective diffusivity peak and its dependence on bacterial concentration. Our results have broad implications on characterizing active fluids using concepts drawn from classical thermodynamics.

show abstract

Section: Experimental Methodsmentioning

confidence: 99%

“…A 2 µl drop of the bacteria-particle suspension is stretched into a fluid film using an adjustable wire frame 7,18,38 to a measured thickness of approximately 100 µm. The film interfaces are stress-free, which minimizes velocity gradients transverse to the film.…”

Section: Experimental Methodsmentioning

confidence: 99%

Particle diffusion in active fluids is non-monotonic in size

et al. 2016

View full text Add to dashboard Cite

show abstract

“…We consider here the equilibrium equations (12) under the hypothesis (23). We look at the equilibrium configurations for every possible value of the angle φ p between the Ax-PFR joining line and the spontaneous bending plane of the Ax, even though the value of actual interest for Euglena is φ p ≈ −2π/9.…”

Section: Emergence Of Non-planaritymentioning

confidence: 99%

“…Instead, the typical outcome is an elastically frustrated configuration of the system, in which the two competing components drive each other out of plane. Under dyneins activation patterns that, in absence of extra-axonemal structures, would produce an asymmetric beat similar to those of Chlamydomonas [23], or Volvox [26], the model specifically predicts the torsional signature of the spinning lasso, which we discuss in the following Section.…”

Section: Introductionmentioning

confidence: 99%

The biomechanical role of extra-axonemal structures in shaping the flagellar beat of Euglena

Cicconofri

Noselli

DeSimone

2020

Preprint

View full text Add to dashboard Cite

We propose and discuss a model for flagellar mechanics in Euglena gracilis. We show that the peculiar non-planar shapes of its beating flagellum, dubbed "spinning lasso", arise from the mechanical interactions between two of its inner components, namely, the axoneme and the paraflagellar rod. The spontaneous shape of the axoneme and the resting shape of the paraflagellar rod are incompatible. The complex non-planar configurations of the coupled system emerge as the energetically optimal compromise between the two antagonistic components. The model is able to reproduce the experimentally observed flagellar beats and their characteristic spinning lasso geometric signature, namely, travelling waves of torsion with alternating sing along the length of the flagellum.

show abstract

“…Striking examples are the graceful wave-like beating of distinct frequencies and wavelengths observed in eukaryotic flagella and cilia -organelles found in animal sperm, algae, protozoa, and in respiratory and reproductive tracts [1][2][3][4][5]7]. Many of the spatio-temporal patterns observed are often planar or near-planar; furthermore, even qualitative aspects of the oscillations are strongly affected by the presence of boundaries and the type of fluid surrounding the cilia [8,9]. Detailed and innovative experiments have revealed aspects of mechanisms by which different axonemal components are integrated and work together [10][11][12][13][15][16][17][18][19][20][21].…”

Section: Introductionmentioning

confidence: 99%

Elastohydrodynamical instabilities of active filaments, arrays and carpets analyzed using slender body theory

Gopinath

Sangani

2020

Preprint

View full text Add to dashboard Cite

The rhythmic motions and wave-like planar oscillations in filamentous soft structures are ubiquitous in biology. Inspired by these, recent work has focused on the creation of synthetic colloid-based active mimics that can be used to move, transport cargo, and generate fluid flows. Underlying the functionality of these mimics is the coupling between elasticity, geometry, dissipation due to the fluid, and active force or moment generated by the system. Here, we use slender body theory to analyze the linear stability of a subset of these -active elastic filaments, filament arrays and filament carpets -animated by follower forces. Follower forces can be external or internal forces that always act along the filament contour. The application of slender body theory enables the accurate inclusion of hydrodynamic effects, screening due to boundaries, and interactions between filaments. We first study the stability of fixed and freely suspended sphere-filament assemblies, calculate neutral stability curves separating stable oscillatory states from stable straight states, and quantify the frequency of emergent oscillations. When shadowing effects due to the physical presence of the spherical boundary are taken into account, the results from the slender body theory differ from that obtained using local resistivity theory. Next, we examine the onset of instabilities in a small cluster of filaments attached to a wall and examine how the critical force for onset of instability and the frequency of sustained oscillations depend on the number of filaments and the spacing between the filaments. Our results emphasize the role of hydrodynamic interactions in driving the system towards perfectly in-phase or perfectly out of phase responses depending on the nature of the instability. Specifically, the first bifurcation corresponds to filaments oscillating inphase with each other. We then extend our analysis to filamentous (line) array and (square) carpets of filaments and investigate the variation of the critical parameters for the onset of oscillations and the frequency of oscillations on the inter-filament spacing. The square carpet also produces a uniform flow at infinity and we determine the ratio of the mean-squared flow at infinity to the energy input by active forces. We conclude by analyzing the bending and buckling instabilities of a straight passive filament attached to a wall and placed in a viscous stagnant flow -a problem related to the growth of biofilms, and also to mechanosensing in passive cilia and microvilli. Taken together, our results provide the foundation for more detailed non-linear analyses of spatiotemporal patterns in active filament systems.

show abstract

Flagellar Kinematics and Swimming of Algal Cells in Viscoelastic Fluids

Cited by 114 publications

References 35 publications

Particle diffusion in active fluids is non-monotonic in size

Particle diffusion in active fluids is non-monotonic in size

The biomechanical role of extra-axonemal structures in shaping the flagellar beat of Euglena

Elastohydrodynamical instabilities of active filaments, arrays and carpets analyzed using slender body theory

Contact Info

Product

Resources

About