Locomotion of Protozoa

Jahn, Theodore L.; Votta, J. J.

doi:10.1146/annurev.fl.04.010172.000521

Cited by 104 publications

(59 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…2A). This motion pattern is widespread in unicellular organisms (Jahn and Votta, 1972), but seems less common in vertebrates. This is a viscous flow analogue of a marine propeller, with the net flow parallel to the rotation axis (C)Representation of the theoretical flow obtained with cilia displaying a circular motion with a tilt of 90° or a tilt of 35°.…”

Section: Directional Cilia-driven Flows: Theory and Modelingmentioning

confidence: 97%

Fluid flows and forces in development: functions, features and biophysical principles

et al. 2012

View full text Add to dashboard Cite

Throughout morphogenesis, cells experience intracellular tensile and contractile forces on microscopic scales. Cells also experience extracellular forces, such as static forces mediated by the extracellular matrix and forces resulting from microscopic fluid flow. Although the biological ramifications of static forces have received much attention, little is known about the roles of fluid flows and forces during embryogenesis. Here, we focus on the microfluidic forces generated by cilia-driven fluid flow and heart-driven hemodynamics, as well as on the signaling pathways involved in flow sensing. We discuss recent studies that describe the functions and the biomechanical features of these fluid flows. These insights suggest that biological flow determines many aspects of cell behavior and identity through a specific set of physical stimuli and signaling pathways.

show abstract

Section: Directional Cilia-driven Flows: Theory and Modelingmentioning

confidence: 97%

Fluid flows and forces in development: functions, features and biophysical principles

et al. 2012

View full text Add to dashboard Cite

show abstract

“…Tip to basal actuation of anterior flagella is, however, seen in some species of protozoa, among the family Trypanosomatidae (Jahn & Votta 1972) and in the genus Peranema (Chen 1950;Chang 1966). Putting such kinematical distinctions aside, in this section we explore a dynamical congruence of the magnetic micro-swimmer to a swimming eukaryotic cell.…”

Section: Do Magnetic Micro-swimmers Move Like Eukaryotic Cells?mentioning

confidence: 99%

Do magnetic micro-swimmers move like eukaryotic cells?

et al. 2008

View full text Add to dashboard Cite

Recent advances in micro-machining allow very small cargos, such as single red blood cells, to be moved by outfitting them with tails made of micrometre-sized paramagnetic particles yoked together by polymer bridges. When a time-varying magnetic field is applied to such a filament, it bends from side to side and propels itself through the fluid, dragging the load behind it. Here, experimental data and a mathematical model are presented showing the dependence of the swimming speed and direction of the magnetic micro-swimmer upon tunable parameters, such as the field strength and frequency and the filament length. The propulsion of the filament arises from the propagation of bending waves between free and tethered ends: here we show that this gives the microswimmer a gait that is intermediate between a eukaryotic cell and a waggled elastic rod. Finally, we extract from the model design principles for constructing the fastest swimming micro-swimmer by tuning experimental parameters.

show abstract

“…This may take the form of precise frequency and phase locking, as frequently found in the swimming of green algae [1], or beating with long-wavelength phase modulations known as metachronal waves, seen in ciliates such as Paramecium [2] and in our own respiratory systems. The remarkable similarity in the underlying molecular structure of flagella across the whole eukaryotic world leads naturally to the hypothesis that a similarly universal mechanism might be responsible for synchronization.…”

mentioning

confidence: 95%

Emergence of Synchronized Beating during the Regrowth of Eukaryotic Flagella

2011

View full text Add to dashboard Cite

A fundamental issue in the biology of eukaryotic flagella is the origin of synchronized beating observed in tissues and organisms containing multiple flagella. Recent studies of the biflagellate unicellular alga Chlamydomonas reinhardtii provided the first evidence that the interflagellar coupling responsible for synchronization is of hydrodynamic origin. To investigate this mechanism in detail, we study here synchronization in Chlamydomonas as its flagella slowly regrow after mechanically induced self-scission. The duration of synchronized intervals is found to be strongly dependent on flagellar length. Analysis within a stochastic model of coupled phase oscillators is used to extract the length dependence of the interflagellar coupling and the intrinsic beat frequencies of the two flagella. Physical and biological considerations that may explain these results are proposed. DOI: 10.1103/PhysRevLett.107.148103 PACS numbers: 87.16.Qp, 05.45.Xt, 47.63.Àb, 87.18.Tt From unicellular organisms as small as a few microns to the largest vertebrates on Earth, we find groups of beating flagella or cilia that exhibit striking spatiotemporal organization. This may take the form of precise frequency and phase locking, as frequently found in the swimming of green algae [1], or beating with long-wavelength phase modulations known as metachronal waves, seen in ciliates such as Paramecium [2] and in our own respiratory systems. The remarkable similarity in the underlying molecular structure of flagella across the whole eukaryotic world leads naturally to the hypothesis that a similarly universal mechanism might be responsible for synchronization. Although this mechanism is poorly understood, one appealing hypothesis is that it results from hydrodynamic interactions between flagella.The role of hydrodynamics in synchronization has been the subject of intense theoretical investigation in the half century since the seminal work of Taylor [3] showed that phase synchronization of nearby undulating sheets minimizes viscous dissipation. Although minimizing dissipation is not a general principle from which to derive dynamics, a growing body of work has identified requirements for synchronization within minimal models involving systems of rotating spheres or helices [4][5][6]. It is now known that oscillators with more than one degree of freedom or those with suitable internal forcing can be synchronized by hydrodynamics [6,7]. Various levels of coordination are also found with more realistic models of flagella [8], which rely necessarily on simplified internal driving of the filaments. Nevertheless, these complex models yield important clues to the generation and regulation of flagellar motion [9].Experimental progress has lagged behind that of theory, due in large part to the challenge of finding a sufficiently simple model system that can be studied under an appropriately broad set of experimental conditions. But recent work [10] on Chlamydomonas reinhardtii (CR, Fig. 1), a biflagellate green alga well developed as a model to stud...

show abstract

Locomotion of Protozoa

Cited by 104 publications

References 0 publications

Fluid flows and forces in development: functions, features and biophysical principles

Fluid flows and forces in development: functions, features and biophysical principles

Do magnetic micro-swimmers move like eukaryotic cells?

Emergence of Synchronized Beating during the Regrowth of Eukaryotic Flagella

Contact Info

Product

Resources

About