CALCITE

For the last 500 million years algae have shaped our environment by fixing CO2 via precipitation of minerals. This mineralization process takes place under strict biological control, giving rise to a variety of complex architectures with spectacular mineral morphologies. Among them are the highly ordered, mesoporous shells of single-celled dinoflagellates, such as Leonella granifera. Their shell is made of calcite that provides the organism with structural support and protection. The shell’s long-range morphological regularity is beyond the reach of current human technology and a paradigm example of regularity in biological systems. However, the biological mechanisms that control the intricate construction of this mineral are largely unknown.

Calcitic shell of L. granifera (left) and cryo-SEM image of the calcite shell crosssection (right)

Elucidating these processes is challenging, since it requires tracking transient, highly soluble inorganic precursor phases at the nanometer-scale. Recent developments in live fluorescent imaging and the cryo-preservation of cells make it possible to follow calcification processes with molecular resolution.