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Single-molecule tracking of Nodal and Lefty in live zebrafish embryos supports hindered diffusion model

Citation

Kuhn, Timo et al. (2022), Single-molecule tracking of Nodal and Lefty in live zebrafish embryos supports hindered diffusion model, Dryad, Dataset, https://doi.org/10.5061/dryad.9kd51c5kg

Abstract

The hindered diffusion model postulates that the movement of a signaling molecule through an embryo is affected by tissue geometry and binding-mediated hindrance, but these effects have not been directly demonstrated in vivo. Here, we visualize extracellular movement and binding of individual molecules of the activator-inhibitor signaling pair Nodal and Lefty in live developing zebrafish embryos using reflected light-sheet microscopy. We observe that diffusion coefficients of molecules are high in extracellular cavities, whereas mobility is reduced and bound fractions are high within cell-cell interfaces. Counterintuitively, molecules nevertheless accumulate in cavities, which we attribute to the geometry of the extracellular space by agent-based simulations. We further find that Nodal has a larger bound fraction than Lefty and shows a binding time of tens of seconds. Together, our measurements and simulations provide direct support for the hindered diffusion model and yield insights into the nanometer-to-micrometer-scale mechanisms that lead to macroscopic signal dispersal.

Funding

European Research Council, Award: 637987

European Research Council, Award: 863952

European Research Council, Award: 637840

Deutsche Forschungsgemeinschaft, Award: SPP 2202 GE 2631/2–1

Deutsche Forschungsgemeinschaft, Award: GE 2631/3–1