Enhanced Diffusion in Active Intracellular Transport

Caspi, Avi; Granek, Rony; Elbaum, Michael

doi:10.1103/physrevlett.85.5655

Cited by 440 publications

(453 citation statements)

References 21 publications

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“…19--23 It turns out that anomalous diffusion is an interesting theoretical framework to address this question. Indeed, although some special cases may be imagined, active transport will in general result in superdiffusion, that is, /x 2 S increases more than linearly with time, 4 or the ADC increases with time. For example, when individual particles evolve at constant speed in straight lines, a situation referred to as the ballistic regime, one simply gets /x 2 SBt d 2 .…”

Section: Major Contribution Of Active Transport To Metabolite Motion mentioning

confidence: 99%

Anomalous Diffusion of Brain Metabolites Evidenced by Diffusion-Weighted Magnetic Resonance Spectroscopy in Vivo

Marchadour

Brouillet

Hantraye

et al. 2012

J Cereb Blood Flow Metab

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Translational displacement of molecules within cells is a key process in cellular biology. Molecular motion potentially depends on many factors, including active transport, cytosol viscosity and molecular crowding, tortuosity resulting from cytoskeleton and organelles, and restriction barriers. However, the relative contribution of these factors to molecular motion in the cytoplasm remains poorly understood. In this work, we designed an original diffusion-weighted magnetic resonance spectroscopy strategy to probe molecular motion at subcellular scales in vivo. This led to the first observation of anomalous diffusion, that is, dependence of the apparent diffusion coefficient (ADC) on the diffusion time, for endogenous intracellular metabolites in the brain. The observed increase of the ADC at short diffusion time yields evidence that metabolite motion is characteristic of hindered random diffusion rather than active transport, for time scales up to the dozen milliseconds. Armed with this knowledge, data modeling based on geometrically constrained diffusion was performed. Results suggest that metabolite diffusion occurs in a low-viscosity cytosol hindered by B2-mm structures, which is consistent with known intracellular organization.

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Section: Major Contribution Of Active Transport To Metabolite Motion mentioning

confidence: 99%

Anomalous Diffusion of Brain Metabolites Evidenced by Diffusion-Weighted Magnetic Resonance Spectroscopy in Vivo

Marchadour

Brouillet

Hantraye

et al. 2012

J Cereb Blood Flow Metab

View full text Add to dashboard Cite

show abstract

“…polystyrene (n=1.6). Many such probes have been used in cellular rheology experiments, being introduced by phagocytosis Caspi, 2000) or micro-injection (Tseng, 2002). Moreover, such particles could potentially be designed to target a specific structure (actin filaments or microtubules) or a specific protein (different integrins or other surface receptors) (Puig-de-Morales, 2004).…”

Section: Vid Using High-intensity Filtered Illuminatormentioning

confidence: 99%

Multiple‐Particle Tracking and Two‐Point Microrheology in Cells

Crocker

Hoffman

2007

Methods in Cell Biology

190

195

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Mechanical stress and stiffness are increasingly recognized to play important roles in numerous cell biological processes, notably cell differentiation and tissue morphogenesis. Little definite is known, however, about how stress propagates through different cell structures or how it is converted to biochemical signals via mechanotransduction, due in large part to the difficulty of interpreting many cell mechanics experiments. A newly developed technique, two-point microrheology (TPM), can provide highly interpretable, quantitative measurements of cells' frequency-dependent shear moduli and spectra of their fluctuating intracellular stresses. TPM is a non-invasive method based on measuring the Brownian motion of large numbers of intracellular particles using multiple particle tracking. While requiring only hardware available in many cell biology laboratories-a phase microscope and digital video camera, as a statistical technique, it also requires the automated analysis of many thousands of micrographs. Here we describe in detail the algorithms and software tools used for such large-scale multiple particle tracking, as well as common sources of error and the microscopy methods needed to minimize them. Moreover, we describe the physical principles behind TPM and other passive microrheology methods, their limitations, and typical results for cultured epithelial cells. ABSTRACT Mechanical stress and stiffness are increasingly recognized to play important roles in numerous cell biological processes, notably cell differentiation and tissue morphogenesis. Little definite is known, however, about how stress propagates through different cell structures or how it is converted to biochemical signals via mechanotransduction, due in large part to the difficulty of interpreting many cell mechanics experiments. A newly developed technique, two-point microrheology (TPM), can provide highly interpretable, quantitative measurements of cells' frequency-dependent shear moduli and spectra of their fluctuating intracellular stresses. TPM is a non-invasive method based on measuring the Brownian motion of large numbers of intracellular particles using multiple particle tracking. While requiring only hardware available in many cell biology laboratories-a phase microscope and digital video camera, as a statistical technique, it also requires the automated analysis of many thousands of micrographs. Here we describe in detail the algorithms and software tools used for such large-scale multiple particle tracking, as well as common sources of error and the microscopy methods needed to minimize them. Moreover, we describe the physical principles behind TPM and other passive microrheology methods, their limitations, and typical results for cultured epithelial cells.

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“…To cite a few, let us recall the problem of diffusion in polymers [12], on liquid surfaces [13], in Lévy flights [14] and enhanced diffusion in active intracellular transport [15]. Many anomalous diffusion systems have a quantum nature, like for instance charge transport in anomalous solids [16], subrecoil laser cooling [17] and the aging effect in quantum dissipative systems [18].…”

Section: Introductionmentioning

confidence: 99%

Canonical quantization of nonlinear many-body systems

Scarfone

2005

Phys. Rev. E

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We study the quantization of a classical system of interacting particles obeying a recently proposed kinetic interaction principle (KIP) [G. Kaniadakis, Physica A 296, 405 (2001)]. The KIP fixes the expression of the Fokker-Planck equation describing the kinetic evolution of the system and imposes the form of its entropy. In the framework of canonical quantization, we introduce a class of nonlinear Schrödinger equations (NSEs) with complex nonlinearities, describing, in the mean field approximation, a system of collectively interacting particles whose underlying kinetics is governed by the KIP. We derive the Ehrenfest relations and discuss the main constants of motion arising in this model. By means of a nonlinear gauge transformation of third kind it is shown that in the case of constant diffusion and linear drift the class of NSEs obeying the KIP is gauge-equivalent to another class of NSEs containing purely real nonlinearities depending only on the field ρ = |ψ| 2 .

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Enhanced Diffusion in Active Intracellular Transport

Cited by 440 publications

References 21 publications

Anomalous Diffusion of Brain Metabolites Evidenced by Diffusion-Weighted Magnetic Resonance Spectroscopy in Vivo

Anomalous Diffusion of Brain Metabolites Evidenced by Diffusion-Weighted Magnetic Resonance Spectroscopy in Vivo

Multiple‐Particle Tracking and Two‐Point Microrheology in Cells

Canonical quantization of nonlinear many-body systems

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