Arthur Lander (Professor, Department of Developmental and Cell Biology, Director, Center for Complex Biological Systems, University of California, Irvine)
Gradients of diffusible signaling molecules known as morphogens orchestrate precise pattern formation during animal development. Despite the fact that the basic task performed by morphogens — informing cells of their locations in space — is fundamentally simple, morphogen gradients are nearly always regulated by complex and elaborate feedback and feed-forward circuits, with contributions by co-receptors, diffusible inhibitors, multiple morphogens, and regulated uptake. Theoretical work has shown that a few of these mechanisms can contribute to the robustness (and thereby the precision) of patterning to fluctuations in morphogen level, but this can at best explain only a small amount of the regulation that is usually present. Focusing on the fruit fly wing disc decapentaplegic gradient, one of the most intensively studied morphogen gradient systems, I will argue that complexity has arisen not only out of the need to meet many "strategic" objectives — peed, noise-filtering, flexibility, adaptability, etc. — but especially out of the need to circumvent the incompatibilities and tradeoffs that invariably arise between them.
SFI Host: David Krakauer