Coccolithogenesis In Scyphosphaera apsteinii ( Prymnesiophyceae)

• Published in: Journal of Phycology
• Main Authors: Drescher, Brandon, Dillaman, Richard M., Taylor, Alison R.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 2012
• Subjects: Ocean acidification
• Online Access: http://dx.doi.org/10.1111/j.1529-8817.2012.01227.x; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1111%2Fj.1529-8817.2012.01227.x; https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1529-8817.2012.01227.x

Coccolithophores are the most significant producers of marine biogenic calcite, although the intracellular calcification process is poorly understood. In the case of S cyphosphaera apsteinii L ohmann 1902, flat ovoid muroliths and bulky, vase‐shaped lopadoliths with a range of intermediate morphologies may be produced by a single cell. This polymorphic species is within the Z ygodiscales, a group that remains understudied with respect to ultrastructure and coccolith ontogeny. We therefore undertook an analysis of cell ultrastructure, morphology, and coccolithogenesis. The cell ultrastructure showed many typical haptophyte features, with calcification following a similar pattern to that described for other heterococcolith bearing species including E miliania huxleyi . Of particular significance was the reticular body role in governing fine‐scale morphology, specifically the central pore formation of the coccolith. Our observations also highlighted the essential role of the inter‐ and intracrystalline organic matrix in growth and arrangement of the coccolith calcite. S . apsteinii secreted mature coccoliths that attached to the plasma membrane via fibrillar material. Time‐lapse light microscopy demonstrated secretion of lopadoliths occurred base first before being actively repositioned at the cell surface. Significantly, growth irradiance influenced the coccosphere composition with fewer lopadoliths being formed relative to muroliths at higher light intensities. Overall, our observations support dynamic metabolic (i.e., in response to growth irradiance), sensory and cytoskeletal control over the morphology and secretion of polymorphic heterococcoliths. With a basic understanding of calcification established, S . apsteinii could be a valuable model to further study coccolithophore calcification and cell physiological responses to ocean acidification.