Seminar Details

Mechanisms of calcium accumulation and mineralization in coccolithophores




Dr. Assaf Gal, Weizmann Institute of Science


Coccolithophores are a major part of phytoplankton communities in modern oceans. The hallmark of these photosynthetic unicellular algae is the production of mineralized scales covering the cell, called coccoliths. The coccoliths are made of calcium carbonate crystals and their deposition to the ocean bed is a dominant sink in the global carbon cycle. Coccolith formation is an intracellular process, exquisitely controlled by the organism, which results in the sculptured morphology of the inorganic crystals. The processes that underlie the formation of the biomineral, from the accumulation of ions from the environment, to the factors that regulate the nucleation and growth of the crystals, are mostly unknown. In our work, we used high-resolution electron and X-ray imaging of coccolithophores along the process of mineralization. These state-of-the-art techniques allowed us to follow intracellular calcium pools in cryo-preserved cells, and revealed a common strategy to concentrate calcium in dense vacuolar bodies. A second line of investigation targeted the molecular interactions that dictate the exact mineralization pattern of the coccoliths. We described a new strategy where the macromolecular recognition between associated organic molecules bypasses the need to control the stochastic nucleation events.

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