Müller P, Rogers KW, Jordan BM, Lee JS, Robson D, Ramanathan S, Schier AF. 2012. Differential diffusivity of Nodal and Lefty underlies a reaction-diffusion patterning system. Science (New York, N.Y.). 336(6082):721-4. Pubmed: 22499809 DOI:10.1126/science.1221920


Biological systems involving short-range activators and long-range inhibitors can generate complex patterns. Reaction-diffusion models postulate that differences in signaling range are caused by differential diffusivity of inhibitor and activator. Other models suggest that differential clearance underlies different signaling ranges. To test these models, we measured the biophysical properties of the Nodal/Lefty activator/inhibitor system during zebrafish embryogenesis. Analysis of Nodal and Lefty gradients revealed that Nodals have a shorter range than Lefty proteins. Pulse-labeling analysis indicated that Nodals and Leftys have similar clearance kinetics, whereas fluorescence recovery assays revealed that Leftys have a higher effective diffusion coefficient than Nodals. These results indicate that differential diffusivity is the major determinant of the differences in Nodal/Lefty range and provide biophysical support for reaction-diffusion models of activator/inhibitor-mediated patterning.

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Photo of Sharad Ramanathan

Sharad Ramanathan studies how the dynamics of the underlying circuits allow cells and organisms to make decisions. To do so he brings together Biology with tools from Applied Math, Microscopy and Microfluidics.

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