Speaker: Dominic Devlin (University of Auckland, Takeuchi lab.)

Title: The evolution of reproducible morphogenesis is facilitated by stem-cell systems

Abstract:

A striking feature of morphogenesis is high reproducibility of complex body shapes despite the stochasticity inherent in biological processes. Understanding what makes morphogenesis reproducible is a focus of developmental biology. Previous research has investigated how reproducibility can be achieved in the transformation of chemical concentration gradients into defined patterns, such as stripes and spots, through reaction and diffusion. However, morphogenesis is the transformation of a spherical zygote into complex multicellular shapes through cellular processes such as cell elongation, division and movement. How can these shape-generating processes be reproducible despite stochasticity in cell movement and geometry? Here, we tackle this question by developing a computational evolutionary-developmental model that incorporates both chemical and cellular processes of morphogenesis. We found that the evolution of complex, reproducible morphologies is always accompanied by the evolution of “stem-cell systems,” in which proliferating stem cells irreversibly differentiate into non-proliferating cells. Contrarily, organisms that evolved complex, yet non-reproducible morphologies did not evolve stem-cell systems. We show that poor reproducibility is a consequence of ongoing, stochastic breaking of symmetry during the course of development as a way of making complex morphologies. In contrast, organisms with highly reproducible morphologies develop complex stalks and folds via differences in the movement and division rates between stem and differentiated cells. This mode of development only requires a single, maternally-derived break in symmetry at zygotic stages, thus making morphogenesis reproducible. Our research suggests that stem-cell systems, which are widely observed in natural multicellular development, are a fundamental tool of developmental biology that facilitate the evolution of complex, reproducible morphogenesis.

Data and Place: June 18, 14:00-
Room 829, 16th building. Komaba Campus, The University of Tokyo
zoom: https://u-tokyo-ac-jp.zoom.us/j/82391386658?pwd=xCc16tS9qBDCfTtR4PfdNEkcpOvU5k.1