Tuesday, Feb. 21st: Tissue flow genetics: mapping the forces that shape complex organs.

Event Date: 

Tuesday, February 21, 2017 - 12:30pm

Event Location: 

  • KITP Auditorium
  • Quantitative Biology Seminar

Developmental biology established principles of how the body plan is laid out, morphogens setup axes, and gene expression patterns determine cell fates - yet how the form of organs emerges from coordinated action of multiple domains of distinct cell types remains elusive. We combine in toto live imaging and automated data analysis with physical modeling to investigate the link between kinetics of global tissue transformations and patterns of force generation during Drosophila gastrulation. We find our visco-elastic model driven by stress proportional to the spatial distribution and anisotropy of two quantitatively measured myosin pools achieves a 90% accurate description of the measured tissue flow - using only 3 parameters. Our analysis shows (i) forces driving the flow arise from non-uniformity of stress, thus spatial myosin modulation is critical for dynamics. Long-range modulation of the anisotropic part along the Dorso-Ventral (DV) axis suggests a novel role for the DV patterning system in convergent extension. (ii) The relation between flow and myosin forcing is non-local, and a transition towards areal incompressibility during germband extension further enhances non-locality. (iii) Mutant analysis indicates mechanical feedback on myosin recruitment relating it to the local strain rate. We conclude that understanding morphogenetic flows requires a fundamentally global perspective.

Sebastian Streichan