Probing the Functional Role of Physical Motion in Development

Kreysing, Moritz

doi:10.1016/j.devcel.2019.10.002

Cited by 4 publications

(2 citation statements)

References 112 publications

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“…Flows of physiological magnitude and duration, created using FLUCS, were shown to be sufficient to localise these proteins [28]. This demonstrates the biological significance of physical transport processes inside cells, as well as the potential of FLUCS for new experiments to reveal the precise role of intracellular fluid flows [31].…”

Section: Introductionmentioning

confidence: 78%

“…We could also consider a localised heating that involves the simultaneous scanning of multiple heat spots along multiple scan paths, enabling the generation of new patterns of fluid flow and transport. This may in turn allow finer control of particles at the micrometre scale, with potential applications in thermal trapping, microrobotics and medicine [31,[44][45][46]. Beyond the parallel-plate setup addressed here, future theoretical modelling could examine the nature of similarly-generated thermoviscous flow in different geometries, and probe in particular the role of confinement in flow generation.…”

Section: Summary and Perspectivementioning

confidence: 99%

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Theoretical model of confined thermoviscous flows for artificial cytoplasmic streaming

Liao¹,

Erben²,

Kreysing³

et al. 2023

Preprint

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Recent experiments in cell biology have probed the impact of artificially-induced intracellular flows in the spatiotemporal organisation of cells and organisms. In these experiments, mild dynamical heating (a few kelvins) via focused infrared light from a laser leads to long-range, thermoviscous flows of the cytoplasm inside a cell. To extend future use of this method in cell biology, popularised as focused-light-induced cytoplasmic streaming (FLUCS), new quantitative models are needed to link the external light forcing to the produced flows and transport. Here, we present a fully analytical, theoretical model describing the fluid flow induced by the dynamical laser stimulus at all length scales (both near the scan path of the laser beam and in the far field) in two-dimensional confinement. We model the effect of the focused light as a small, local temperature change in the fluid, which causes a small change in both the density and the viscosity of the fluid locally. In turn, this results in a locally compressible fluid flow. We analytically solve for the instantaneous flow field induced by the translation of a heat spot of arbitrary time-dependent amplitude along a scan path of arbitrary length. We show that the leading-order instantaneous flow field results from the thermal expansion of the fluid and is independent of the thermal viscosity coefficient. This leadingorder velocity field is proportional to the thermal expansion coefficient and the magnitude of the temperature perturbation, with far-field behaviour typically dominated by a source or sink flow and proportional to the rate of change of the heat-spot amplitude. In contrast, and in agreement with experimental measurements, the net displacement of a material point due to a full scan of the heat spot is quadratic in the heat-spot amplitude, as it results from the interplay of thermal expansion and thermal viscosity changes. The corresponding average velocity of material points over a scan is a hydrodynamic source dipole in the far field, with direction dependent on the relative importance of thermal expansion and thermal viscosity changes. Our quantitative findings show excellent agreement with recent experimental results and will enable the design of new controlled experiments to establish the physiological role of physical transport processes inside cells.

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Section: Introductionmentioning

confidence: 78%

Section: Summary and Perspectivementioning

confidence: 99%

Theoretical model of confined thermoviscous flows for artificial cytoplasmic streaming

Liao¹,

Erben²,

Kreysing³

et al. 2023

Preprint

View full text Add to dashboard Cite

show abstract

Theoretical model of confined thermoviscous flows for artificial cytoplasmic streaming

et al. 2023

View full text Add to dashboard Cite

ISO-FLUCS: symmetrization of optofluidic manipulations in quasi-isothermal micro-environments

Minopoli

Wagner

Erben

et al. 2023

eLight

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Recently, it has been demonstrated that thermoviscous flows can be used for a range of fine micromanipulations, such as moving the cytoplasm of cells and developing embryos, intracellular rheology, and femtonewton-range force measurements. These flows, also known as focused-light-induced cytoplasmic streaming (FLUCS), are induced by mid-infrared laser scanning of a temperature spot through the sample. However, localized laser scanning can inflict temperature perturbations of several Kelvins on the sample, potentially eliciting unspecific biological responses. In this study, we demonstrate how exploiting symmetry relations during laser scanning effectively disentangles laser heating and flow induction. We introduce flow-neutral scan sequences that use dynamic photothermal stimuli and spatiotemporal symmetry relations of scanning bridging up to three distinct time scales. We leverage further insights from a recently published analytical model of flow fields to present quasi-homogenous temperature distributions that leave flow lines and their local and directed character largely invariant. We present practical, intuitive solutions through predesigned sets of scan lines with near isothermal distributions and demonstrate that they are sufficient to generate and control flows in Caenorhabditis elegans embryos on a magnitude well in excess of endogenous flow velocities. Our results enable the separation of two previously tightly linked classes of physical stimuli, introduce a new, even less invasive standard for performing FLUCS perturbations, and pave the way for new unexplored avenues in the fields of soft matter and biomedicine. Graphical Abstract

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Probing the Functional Role of Physical Motion in Development

Cited by 4 publications

References 112 publications

Theoretical model of confined thermoviscous flows for artificial cytoplasmic streaming

Theoretical model of confined thermoviscous flows for artificial cytoplasmic streaming

Theoretical model of confined thermoviscous flows for artificial cytoplasmic streaming

ISO-FLUCS: symmetrization of optofluidic manipulations in quasi-isothermal micro-environments

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