137 Oral - Patterning and Morphogenesis I
Saturday April 09, 8:15 AM - 8:30 AM

Authors:
Celia Smits ^1,2; Sayantan Dutta ^1,3; Sebastian Streichan ^4,5; Stanislav Shvartsman ^1,2,3,6

Affiliations:
1) Lewis Sigler Institute for Integrative Genomics, Princeton University, NJ; 2) Department of Molecular Biology, Princeton University, NJ; 3) Department of Chemical and Biological Engineering, Princeton University, NJ; 4) Department of Physics, University of California Santa Barbara, CA; 5) Biomolecular Science and Engineering, University of California Santa Barbara, CA; 6) Center for Computational Biology, Flatiron Institute, Simons Foundation, NY

Keywords:
w. biomechanical forces; y. live imaging

Morphogenetic processes must resist biological noise and environmental perturbations to faithfully construct an adult organism. We are investigating the mechanisms underlying such robustness in Drosophila embryogenesis. Here, we focus on bilateral symmetry maintenance during body axis extension. In Drosophila, the body axis extends parallel to the long axis of the embryo during gastrulation. However, we present evidence that there is a certain amount of left-right variation in midline position that is corrected as the tissue elongates. To determine the origin of this correction, we investigated a class of mutants where embryos exhibit a characteristic “corkscrew” phenotype. We find that in these mutants, the midline begins twisting along the left-right axis shortly after the onset of axis extension. Using a combination of classical genetics, light sheet microscopy, particle image velocimetry, dimensionality reduction and computation modelling, we characterize the mechanics and genetics that underlie this twisting. Finally, we propose a model where invagination of the posterior midgut acts to disperse the forces of convergent extension in a bilaterally symmetric manner, which is required to maintain bilateral symmetry in the face of stochastic differences in lateral extension rates. Overall, this work indicates that coordination of morphogenetic movements and mechanics act to rein in random biological noise and ensure correct tissue flow and proper morphogenesis.