Polarized cortical tension drives zebrafish epiboly movements.
The principles underlying the biomechanics of morphogenesis are largely unknown. Epiboly is an essential embryonic event in which three tissues coordinate to direct the expansion of the blastoderm. How and where forces are generated during epiboly, and how these are globally coupled remains elusive. Here we developed a method, hydrodynamic regression (HR), to infer 3D pressure fields, mechanical power, and cortical surface tension profiles. HR is based on velocity measurements retrieved from 2D+T microscopy and their hydrodynamic modeling. We applied HR to identify biomechanically active structures and changes in cortex local tension during epiboly in zebrafish. Based on our results, we propose a novel physical description for epiboly, where tissue movements are directed by a polarized gradient of cortical tension. We found that this gradient relies on local contractile forces at the cortex, differences in elastic properties between cortex components and the passive transmission of forces within the yolk cell. All in all, our work identifies a novel way to physically regulate concerted cellular movements that might be instrumental for the mechanical control of many morphogenetic processes.
Instituto de Biología Molecular de Barcelona, Consejo Superior de Investigaciones Científicas, Barcelona, Spain.
Amayra
A
Hernández-Vega
Instituto de Biología Molecular de Barcelona, Consejo Superior de Investigaciones Científicas, Barcelona, Spain.
María
M
Marsal
Instituto de Biología Molecular de Barcelona, Consejo Superior de Investigaciones Científicas, Barcelona, Spain.
Philippe-Alexandre
PA
Pouille
Advanced Digital Microscopy Core Facility (ADMCF), Institute for Research in Biomedicine (IRB Barcelona) The Barcelona Institute of Science and Technology, Barcelona, Spain.
Sébastien
S
Tosi
Advanced Digital Microscopy Core Facility (ADMCF), Institute for Research in Biomedicine (IRB Barcelona) The Barcelona Institute of Science and Technology, Barcelona, Spain.
Julien
J
Colombelli
Institute for Bioengineering of Catalonia, Barcelona, Spain.|CIBER de Enfermedades Respiratorias (CIBERES), Madrid, Spain.|Facultad de Medicina i Ciencies de la Salut, Universitat de Barcelona, Barcelona, Spain.
Tomás
T
Luque
Institute for Bioengineering of Catalonia, Barcelona, Spain.|CIBER de Enfermedades Respiratorias (CIBERES), Madrid, Spain.|Facultad de Medicina i Ciencies de la Salut, Universitat de Barcelona, Barcelona, Spain.
Daniel
D
Navajas
Departament de Física de la Matèria Condensada, Facultat de Física, Universitat de Barcelona, Barcelona, Spain.
Ignacio
I
Pagonabarraga
Instituto de Biología Molecular de Barcelona, Consejo Superior de Investigaciones Científicas, Barcelona, Spain embbmc@ibmb.csic.es.
Enrique
0000-0002-6926-910X
E
Martín-Blanco
D000818:Animals; D001696:Biomechanical Phenomena; D001756:Blastoderm / Q000254:growth & development*; D009068:Movement; D015027:Zebrafish / Q000196:embryology*
epiboly; hydrodynamics; mechanics; morphogenesis; zebrafish