On culture artefacts in coccolith morphology

Abstract

Coccolith malformations occur more frequently in cultured specimens than in specimens from natural samples, a phenomenon commonly termed 'culture artefacts'. The causes of culture artefacts are unknown. Here, we tested the effect of culture flask shape, mixing, and cell density on the morphology of Emiliania huxleyi coccoliths. While there was no effect of different culture flask types typically used in coccolithophore culturing, continuous mixing reduced the percentage of malformations by ca. 11 % in exponential-phase cells (cell density ca. 80 9 10 3 cells per ml) and ca. 17 % in stationary-phase cells (cell density ca. 2 9 10 6 cells per ml). Stationary-phase cells displayed 19 % more malformations than mid-exponentialphase cells when not mixed at all and 20 % more malformations when continuously mixed. It is concluded that the lack of mixing and unnaturally high cell densities, typical for coccolithophore stock cultures, are partly responsible for culture artefacts.

Phosphorus limitation and heat stress decrease calcification in <i>Emiliania huxleyi</i>

“…6 %) than in our control cultures (ca. 20 %), lending support to the hypothesis that coccolith malformations occur more frequently in culture (Langer et al, 2013a). The types of malformations, however, appear to be similar, indicating that the affected physiological mechanisms are the same.…”

Insight into <i>Emiliania huxleyi</i> coccospheres by focused ion beam sectioning

“…This approach might yield a satisfactory result for Calcidiscus leptoporus, which typically produces one layer of coccoliths only. However, the situation is more complicated in E. huxleyi, because the species does not stop coccolith production upon cessation of cell division (Langer et al, 2013a) or completion of a coccosphere, resulting in multiple layers of coccoliths (Paasche, 2002). These multiple layers can even be seen in exponentially growing cultures such as the one analysed here.…”

“…Both the chemical composition of coccoliths and the morphology of the coccosphere as well as the coccoliths provide information about physiological parameters such as growth and calcification rate at different times in the geological past (Stoll and Schrag, 2000;Gibbs et al, 2013). The morphological analysis of coccospheres and coccoliths relies on scanning electron microscopy (SEM), a tool which renders the accurate determination of size and morphological modification possible (Young and Ziveri, 2000;Langer et al, 2013a). Until now, SEM samples were often prepared by means of conventional sample preparation methods -either smearing coccoliths onto sample holders or using the microtome to create single cross sections through the cells.…”

Therapeutic Applications of Phytoplankton, with an Emphasis on Diatoms and Coccolithophores

“…This property is advantageous as these structures can be produced in a highthroughput fashion with appropriate culture conditions. [27] Extraction and concentration of diatoms and coccolith skeleton have been simplified over time and can now be easily extracted using commercial cleaning fluids. [28] Coccolithophores have been intensively investigated to reveal insights for the mechanism of calcification and formation of their unique morphologies, [29] to genome identification, [30] their interaction with solar light exposure in the ocean, [31] and impact Overview of potential applications of phytoplankton with focus on diatoms and coccolithophores/coccoliths: diagnostics (label free, or surface functionalization with contrasting agents), surface functionalization as carriers for drug delivery for therapeutic purposes, source of bioactive compounds with relevance for drug discovery, cell anchoring substrates/production of metabolites (as molecular factories for the release of therapeutic compounds inducing cell apoptosis), or as a source of oxygen for autotrophic tissue engineering applications (phytoplankton could be co-integrated with mammalian cells inside hydrogels to provide oxygen and nutrients in hypoxic tissues).…”