Abstract

The spherical embryos of the green alga Volvox turn themselves inside out through a programme of cell shape changes at the close of their development. This inversion shares features such as invagination with events of cell sheet folding in animals, and has therefore become a simple model system for morphogenesis. Through the combination of three-dimensional time-lapse visualisations of inversion and a theoretical model in which cell shape changes appear as variations of the intrinsic stretches and curvatures of an elastic shell, we identify the mechanical ingredients necessary for inversion. We go on to quantify the variability of inversion, and use it to analyse the interplay of mechanics, geometry, and regulation during inversion. These analyses begin to reveal evolutionary aspects of developmental complexity in the Volvocalean algae.
Joint work with: Stephanie Höhn, Aurelia R. Honerkamp-Smith, Julius B. Kirkegaard, and Raymond E. Goldstein