livMatS Colloquium | Dr. Naomi Nakayama (Imperial College London) | What determines biological shape? A case of the dandelion pappus
Biological organisms regulate the size and shape of their organs robustly, but why? To untangle factors determining biological forms, we have embarked on structural-functional studies of the dandelion pappus. Pappus, or plume, is a bundle of many hair-like structures that enhance air drag to aid the flight of the diaspore. Pappus is likely to confer an evolutionary advantage since it has been raised in multiple clades independently. By examining the air-pappus interaction with a bespoke wind tunnel, we have uncovered a previously unobserved fluid behaviour – a vortex ring separated from the body but staying stably at a constant distance. The dandelion pappus does not always remain open; it closes reversibly when the surrounding air is wet. We analyzed the cellular deformation patterns within the base of the flower, the tissue acting as an actuator. Using a computational model (2D FEM), we found that this actuator is a bilayer ring. This pappus morphing is likely to have an evolutionary advantage as it increases dispersal distance by 25%. Through investigation like this, we can assess the functional pulls on determining a biological form. However, they are likely not the only drivers; other factors are likely at play, such as developmental toolkits plants possess, and the energetics of tissue/organ construction. A future direction involving synthetic developmental biology will be discussed.
Prior to joining Imperial College in 2019 as a Senior Lecturer (Associate Professor), Naomi was a group leader at the University of Edinburgh, first as a Chancellor's Fellow and then a Royal Society University Research Fellow. She received a PhD in Molecular, Cellular, and Developmental Biology from Yale University (USA) for molecular dissection of organ-identity-dependent differentiation in Arabidopsis petals and stamens. As a postdoctoral fellow at University of Bern (Switzerland) and École Normale Supérieure de Lyon (France), Naomi developed new methods for mechanical treatment and characterization of living tissues. She held a European Molecular Biology Organization (EMBO) Long-term Fellowship and a Roche Research Fellowship for her postdoctoral research.