Morphogen gradients provide long-range positional information by extending across a developing field. To ensure reproducible patterning, their profile is invariable despite genetic or environmental fluctuations. Common models assume a morphogen profile that decays exponentially. Here, we show that exponential profiles cannot, at the same time, buffer fluctuations in morphogen production rate an...

The fundamental problem of pattern formation for example, how to specify body axes, limbs, digits during development comes down to interpreting a common set of genetic instructions differently at different locations in space (Wolpert 1969). (See Figure 1.1 for an illustration). In all multicellular animals, this process is orchestrated by morphogens, molecules that are produced at discrete site...

In multicellular organisms, the initial patterns of gene expression are regulated by spatial gradients of biochemical factors, known as morphogen gradients. Because of biochemical noise in the morphogen gradients there are associated spatial errors in the positions of target gene patterns. Using a simple single morphogen and/or single target gene model, we use propagation of error analysis to d...

During development, morphogen gradients precisely determine the position of gene expression boundaries despite the inevitable presence of fluctuations. Recent experiments suggest that some morphogen gradients may be interpreted prior to reaching steady-state. Theoretical work has predicted that such systems will be more robust to embryo-to-embryo fluctuations. By analyzing two experimentally mo...

The importance of morphogens is a central concept in developmental biology. Multiple-fate patterning and the robustness of the morphogen gradient are essential for embryo development. The ways by which morphogens diffuse from a local source to form long distance gradients can differ from one morphogen to the other, and for the same morphogen in different organs. This paper will study the mechan...

The patterning of many developing tissues is organized by morphogens. Genetic and environmental perturbations of gene expression, protein synthesis and ligand binding are among the sources of unreliability that limit the accuracy and precision of morphogen-mediated patterning. While it has been found that the robustness of morphogen gradients to the perturbation of morphogen synthesis can be en...

A large, diverse, and growing number of strategies have been proposed to explain how morphogen gradients achieve robustness and precision. We argue that, to be useful, the evaluation of such strategies must take into account the constraints imposed by competing objectives and performance tradeoffs. This point is illustrated through a mathematical and computational analysis of the strategy of se...

An expansion-repression mechanism by which morphogen gradients can adjust to size and growth had been postulated as a model. Now, its molecular nature has been uncovered.