Coccolithogenesis In Scyphosphaera apsteinii (Prymnesiophyceae)

Abstract

Coccolithophores are the most significant producers of marine biogenic calcite, although the intracellular calcification process is poorly understood. In the case of Scyphosphaera apsteinii Lohmann 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 Zygodiscales, 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 Emiliania 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.

Proteomic analysis of skeletal organic matrix from the stony coral Stylophora pistillata

“…iomineralizing organisms are found in all biological kingdoms and incorporate a variety of metals, from sodium to lead, as major components of minerals whose nucleation and growth are under a range of biological control (1)(2)(3)(4)(5). The skeletal organic matrix (SOM), occluded in the mineral, has been implicated as a source of the increased strength of biominerals over comparable geominerals and has long been hypothesized to aid in the stabilization, nucleation, growth, and spatial orientation of biominerals (6)(7)(8)(9)(10).…”

Coccolithophore biomineralization: New questions, new answers

“…Supporting this hypothesis, the involvement of Ca 2+ /H + exchangers is predicted to be kinetically feasible in the modelling study of Holz et al, [25]. In this respect the cortical endoplasmic reticulum could potentially play a role as the primary recipient of (Figure 1) [8,9,29].…”

Competition between Silicifiers and Non-silicifiers in the Past and Present Ocean and Its Evolutionary Impacts

“…An excellent example of this occurs within the haptophytes. Some species, such as Prymnesium neolepis (Yoshida et al, 2006) and S. apsteinii (Drescher et al, 2012) produce wholly-or partially siliceous scales, while some calcareous species such as Calcidiscus leptoporus possess SITLs and have a metabolic requirement for silicon to complete normal production of their calcified scales (Durak et al, 2016). Other species however, have lost SIT-Ls (and SITs), and show no effect of germanium toxicity disrupting biomineralization.…”