Regensburg 2007 – scientific programme

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SYNF: Symposium Nonlinear and Fractional Transport in Complex Systems

SYNF 1: Nonlinear and Anomalous Transport in Complex Systems

SYNF 1.3: Invited Talk

Wednesday, March 28, 2007, 15:45–16:15, H1

Morphogen Transport in Epithelia — •Tobias Bollenbach — Max-Planck-Institut für Physik komplexer Systeme, Nöthnitzer Strasse 38, 01187 Dresden, Germany — Department of Systems Biology, Harvard Medical School, 200 Longwood Avenue, Boston, MA 02115, USA

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. Here, we study morphogen transport through the tissue using a combined theoretical and experimental approach. Recent experiments on the morphogen Decapentaplegic (Dpp) in the fruit fly Drosophila melanogaster provide evidence for the importance of a cellular transport mechanism that was termed “planar transcytosis”. In this mechanism, morphogens are transported through the 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. We further discuss the effects of spatial disorder on the steady state concentration profile and address the important question how precise the positional information encoded in a morphogen gradient can be. Finally, we relate our theoretical work to recent experiments on the kinetics and precision of morphogen gradient formation.