Coccolithophores are marine phytoplankton that evolved about 200 million years ago and ever since dominated the world oceans. These unicellular photosynthetic organisms cover themselves with calcified scales called coccoliths. The coccolith is an intricate array of calcite crystals that is formed inside a specialized organelle and upon completion extruded to the cell surface.
Coccolith production in the ocean can be so intense that coccolithophore blooms are visible from outer space, and over geological time scale coccoliths are accumulated at the ocean floor and give rise to massive chalk formations. Currently, it is becoming urgent to understand if changing climate conditions, and in particular ocean acidification, is likely to affect coccolithophores and their role in the global carbon cycle through calcification and photosynthesis.
The biological mechanisms that control the intricate crystallization process are just starting to be revealed. It appears that coccolith formation proceeds via multiple intermediate stages within the cell and is orchestrated by the activity of various organic components. In order to understand the cellular relations between the various organic and inorganic components we are using state-of-the-art microscopy to generate molecular scale resolution images of snap-frozen cells, as close as possible to their native state.
Coccolith of the species Calcidiscus leptoporus