(in collaboration with Tony Harris and Rodrigo Fernandez-Gonzalez of University of Toronto, and Katja Röper of the MRC Laboratory of Molecular Biology)

Tissue growth and morphogenesis are fundamental processes in developmental biology. Typically, morphogenesis involves coupling between biochemical and mechanical mechanisms on several length and time scales. As an example, a schematic of epithelial invagination, triggered by loss of Dpp signaling in the Drosophila wing disc, is shown below.

(Apical constriction and axial shortening produce an apical epithelial invagination. Adapted from Widmann and Dahmann with permission, © 2009 The Company of Biologists.)

We have modeled several morphogenetic processes for Drosophila epithelia, including dorsal closure, germ-band extension, and tubulogenesis of the salivary gland. In each case, we code known biochemical pathways into a chemo-mechanical model to explore how signaling proteins lead to tissue deformation and movement. Computer simulation allows us to capture interesting features observed in experiments, and to elucidate their underlying causes.

An example is depicted below for dorsal closure. The amnioserosa tissue contracts through several phases during dorsal closure under the coordinated actions of the cell shape pulsation and "purse-string" contraction of a supracellular actin cable. Each is the result of mechano-chemical coupling involving intricate signaling pathways and actomyosin remodeling. In the following movies, the prediction of the model (left) is compared with an experimental observation (right) of Blanchard et al. (image and video used with permission, © 2010 The Company of Biologists).