Thermokinetic Approach of Single Particles and Clusters Involving Anomalous Diffusion under Viscoelastic Response

Santamaría‐Holek, I.; Jm, Rubí; Gadomski, Adam

doi:10.1021/jp0675375

Cited by 35 publications

(54 citation statements)

References 37 publications

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“…The elastic forces confine the vesicles in the cluster with a frequencythat characterizes the magnitude of the force through its relationship with the effective elastic constant k of the cytoskeleton [26]–[27]. At rest, when the velocity v = 0 , the vesicle cluster mobilization is restricted by the elastic forces to an internal region of the neuron, defined here as an initial position r 0 , i , where i denotes the i th vesicle.…”

Section: Methodsmentioning

confidence: 99%

Biophysics of Active Vesicle Transport, an Intermediate Step That Couples Excitation and Exocytosis of Serotonin in the Neuronal Soma

et al. 2012

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Transmitter exocytosis from the neuronal soma is evoked by brief trains of high frequency electrical activity and continues for several minutes. Here we studied how active vesicle transport towards the plasma membrane contributes to this slow phenomenon in serotonergic leech Retzius neurons, by combining electron microscopy, the kinetics of exocytosis obtained from FM1-43 dye fluorescence as vesicles fuse with the plasma membrane, and a diffusion equation incorporating the forces of local confinement and molecular motors. Electron micrographs of neurons at rest or after stimulation with 1 Hz trains showed cytoplasmic clusters of dense core vesicles at 1.5±0.2 and 3.7±0.3 µm distances from the plasma membrane, to which they were bound through microtubule bundles. By contrast, after 20 Hz stimulation vesicle clusters were apposed to the plasma membrane, suggesting that transport was induced by electrical stimulation. Consistently, 20 Hz stimulation of cultured neurons induced spotted FM1-43 fluorescence increases with one or two slow sigmoidal kinetics, suggesting exocytosis from an equal number of vesicle clusters. These fluorescence increases were prevented by colchicine, which suggested microtubule-dependent vesicle transport. Model fitting to the fluorescence kinetics predicted that 52–951 vesicles/cluster were transported along 0.60–6.18 µm distances at average 11–95 nms−1 velocities. The ATP cost per vesicle fused (0.4–72.0), calculated from the ratio of the ΔGprocess/ΔGATP, depended on the ratio of the traveling velocity and the number of vesicles in the cluster. Interestingly, the distance-dependence of the ATP cost per vesicle was bistable, with low energy values at 1.4 and 3.3 µm, similar to the average resting distances of the vesicle clusters, and a high energy barrier at 1.6–2.0 µm. Our study confirms that active vesicle transport is an intermediate step for somatic serotonin exocytosis by Retzius neurons and provides a quantitative method for analyzing similar phenomena in other cell types.

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Section: Methodsmentioning

confidence: 99%

Biophysics of Active Vesicle Transport, an Intermediate Step That Couples Excitation and Exocytosis of Serotonin in the Neuronal Soma

et al. 2012

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“…3, is weaker than in suspensions of linear objects, for which G 0 ) G 00 [9,26,27]. This suggests that the suspected protein chains are held by weak forces.…”

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confidence: 97%

“…This viscoelasticity is interpreted as entrapment of the probe particles by the network of linear objects at short times, when the elastic response stems from interactions with the flexible chains. At long times, the characteristic dimensions of particles motion are longer than the characteristic spacing of the network and particle motion is not affected by the network [9,27].…”

mentioning

confidence: 99%

Viscoelasticity in Homogeneous Protein Solutions

et al. 2009

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We probe the transport properties in protein solutions stable with respect to any, solid or liquid, phase separation as a step in the understanding of transport in the cytosol of live cells. We determine the mean-squared displacement of probe particles in the time range 10;{-3}-10 s in solutions of a model protein. The tested solutions exhibit significant elasticity at high frequencies, while at low frequencies, they are purely viscous. We attribute this viscoelasticity to a dense network of weakly-bound chains of protein molecules with characteristic lifetime of 10-100 ms. The found intrinsic viscoelasticity of protein solutions should be considered in biochemical kinetics models.

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“…One systematic way of dealing with these types of memory effects is to replace the first order time derivative in the conventional hydrodynamic (transport) equations by a fractional time derivative which is interpreted as the memory or the after-effect of the underlying stochastic process [14]. These effects on correlation functions have been studied for some complex fluids [9,14,15].…”

Section: Introductionmentioning

confidence: 99%

Fractional Time Fluctuations in Viscoelasticity: A Comparative Study of Correlations and Elastic Moduli

Rodríguez

Salinas-Rodríguez

Fujioka

2018

Entropy

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Abstract:We calculate the transverse velocity fluctuations correlation function of a linear and homogeneous viscoelastic liquid by using a generalized Langevin equation (GLE) approach. We consider a long-ranged (power-law) viscoelastic memory and a noise with a long-range (power-law) auto-correlation. We first evaluate the transverse velocity fluctuations correlation function for conventional time derivativesĈ NF − → k , t and then introduce time fractional derivatives in their equations of motion and calculate the corresponding fractional correlation function. We find that the magnitude of the fractional correlationĈ F − → k , t is always lower than the non-fractional one and decays more rapidly. The relationship between the fractional loss modulusis also calculated analytically. The difference between the values of G (ω) for two specific viscoelastic fluids is quantified. Our model calculation shows that the fractional effects on this measurable quantity may be three times as large as compared with its non-fractional value. The fact that the dynamic shear modulus is related to the light scattering spectrum suggests that the measurement of this property might be used as a suitable test to assess the effects of temporal fractional derivatives on a measurable property. Finally, we summarize the main results of our approach and emphasize that the eventual validity of our model calculations can only come from experimentation.

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Thermokinetic Approach of Single Particles and Clusters Involving Anomalous Diffusion under Viscoelastic Response

Cited by 35 publications

References 37 publications

Biophysics of Active Vesicle Transport, an Intermediate Step That Couples Excitation and Exocytosis of Serotonin in the Neuronal Soma

Biophysics of Active Vesicle Transport, an Intermediate Step That Couples Excitation and Exocytosis of Serotonin in the Neuronal Soma

Viscoelasticity in Homogeneous Protein Solutions

Fractional Time Fluctuations in Viscoelasticity: A Comparative Study of Correlations and Elastic Moduli

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