Simple physical models of diatom morphogenesis to drive experiment

Lisa Willis
CoMPLEX, University College London
Presented in the Embryo Physics Course, January 25, 2012


Over the last 200 million years, a number of aquatic unicellular eukaryotic organisms have evolved techniques to sequester and assemble biominerals into exogenous structures. The results seen today are high-fidelity, mineralized exoskeletons featuring patterned complex nanoscale ornamentations that defy synthesis in vitro. Among these organisms, diatoms are of particular topical importance due to their fundamental role in the carbon cycle, in food chains ascending to fish, and the potential value of their biosilica shells to developing nanotechnologies. Their species-specific mineralized shells, which putatively optimize mechanical strength for protection and light-harvestation for photosynthesis, have astoundingly diverse morphologies, with structures that span scales from 5 nm to 0.5 mm. At the finest scale are structures called pore occlusions, which in a matter of minutes assemble and solidify under ambient physiological conditions into roughly deterministic patterns that are conserved within species, but which vary between species. Very little is known about this diatom biosilica assembly, yet if the mechanisms are simple or synthetically imitable, or if they can be externally manipulated, then they are potentially of great interest to industry.

I am developing simple, physically motivated models of biosilica assembly, with the ultimate aim of identifying testable predictions to distinguish between the different models. I will give a brief primer on the biology of diatoms, then talk about one of these models in detail.


I graduated in 2004 with a degree in mathematics from the University of Oxford. Then I spent one fantastic year working in South Africa at a scientific teaching and research institute called AIMS, the African Institute for Mathematical Sciences. I returned to the UK to enter an interdisciplinary PhD program, CoMPLEX, at University College London,  where students can select a PhD which marries their interests in the life sciences, mathematics, and the physical sciences.  Half-way through my PhD I learned of diatoms and their fascinating exoskeletons, and I started to work on them.  This has led to a short research fellowship, with Eileen Cox (Natural History Museum, London) and Tom Duke (London Centre for Nanotechnology, UCL), which is currently underway.

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