Probing the transition from a fast local scale diffusion to a slow global diffusion of morphogens in-vivo

Abstract

Morphogen concentration gradients form within the developing embryo at different stages. Cells respond to these gradients in a concentration-dependent manner leading to spatial patterning of the developing embryo. The formation of these gradients is, however, incompletely understood.In the case of Squint, a nodal morphogen responsible for mesendoderm induction and left-right patterning in early zebrafish embryos, diffusion coefficients measured over different length scales vary by almost two orders of magnitude, with D∼ 60 μm2/s at a length scale of < 1 μm, and D∼2 μm2/s at the tissue level of >100 μm.