Berlin 2005 – wissenschaftliches Programm
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AKB: Biologische Physik
AKB 75: Nonlinear Phenomena and Pattern Formation
AKB 75.4: Vortrag
Mittwoch, 9. März 2005, 11:15–11:30, TU H2013
Robustness and Precision in Morphogen Gradient Formation — •Tobias Bollenbach1, Karsten Kruse1, Periklis Pantazis2, Marcos González-Gaitán2, and Frank Jülicher1 — 1MPI for Physics of Complex Systems, Nöthnitzerstr. 38, 01187 Dresden — 2MPI for Molecular Cell Biology and Genetics, Pfotenhauerstr. 108, 01307 Dresden
Morphogens are signaling molecules that play a key role in animal development. They spread from a restricted source into an adjacent target tissue forming a concentration gradient. The fate of cells in the target tissue is determined by the local concentration of such morphogens. Morphogen transport through the tissue has been studied in experiments which lead to the suggestion of several transport mechanisms. While diffusion in the extracellular space contributes to transport, recent experiments on the morphogen Dpp in the fruit fly Drosophila provide evidence for the importance of a cellular transport mechanism that was termed “planar transcytosis”. In this mechanism, morphogens are transported through cells by repeated rounds of internalization and externalization. Starting from a microscopic description of these processes, we derive nonlinear transport equations which describe the interplay of transcytosis and passive diffusion. We find that transcytosis leads to an increased robustness of the created gradients with respect to morphogen over-expression. This robustness has been observed in experiments. We finally relate our description to recent experiments.