Coccolithophore calcification studied by single-cell impedance cytometry: Towards single-cell PIC:POC measurements

Douwe S De Bruijn,Paul M Ter Braak,Dedmer B Van De Waal,Wouter Olthuis,Albert Van Den Berg

doi:10.1016/j.bios.2020.112808

Abstract

Since the industrial revolution 30% of the anthropogenic CO2 is absorbed by oceans, resulting in ocean acidification, which is a threat to calcifying algae. As a result, there has been profound interest in the study of calcifying algae, because of their important role in the global carbon cycle. The coccolithophore Emiliania huxleyi is considered to be globally the most dominant calcifying algal species, which creates a unique exoskeleton from inorganic calcium carbonate platelets. The PIC (particulate inorganic carbon): POC (particulate organic carbon) ratio describes the relative amount of inorganic carbon in the algae and is a critical parameter in the ocean carbon cycle.In this research we explore the use of microfluidic single-cell impedance spectroscopy in the field of calcifying algae. Microfluidic impedance spectroscopy enables us to characterize single-cell electrical properties in a non-invasive and label-free way. We use the ratio of the impedance at high frequency vs. low frequency, known as opacity, to discriminate between calcified coccolithophores and coccolithophores with a calcite exoskeleton dissolved by acidification (decalcified).We have demonstrated that using opacity we can discriminate between calcified and decalcified coccolithophores with an accuracy of 94.1%. We have observed a correlation between the measured opacity and the cell height in the channel, which is supported by FEM simulations. The difference in cell density between calcified and decalcified cells can explain the difference in cell height and therefore the measured opacity.

Highlights

Since the industrial revolution 30% of the anthropogenic CO2 is absorbed by oceans (Sabine et al, 2004), resulting in ocean acidification (Feely et al, 2004), which is a threat to calcifying algae (Meyer and Riebesell, 2015; Riebesell et al, 2000)
In this research we explore the use of microfluidic single-cell impedance spectroscopy in the field of calcifying algae
Since the industrial revolution 30% of the anthropogenic CO2 is absorbed by oceans (Sabine et al, 2004), resulting in ocean acidification (Feely et al, 2004), which is a threat to calcifying algae (Meyer and Riebesell, 2015; Riebesell et al, 2000)

Summary

Introduction

Since the industrial revolution 30% of the anthropogenic CO2 is absorbed by oceans (Sabine et al, 2004), resulting in ocean acidification (Feely et al, 2004), which is a threat to calcifying algae (Meyer and Riebesell, 2015; Riebesell et al, 2000). There has been pro found interest in these calcifying algae, boosted by their major role in the global carbon cycle (Armstrong et al, 2001; Bach et al, 2013; Gafar et al, 2019; Monteiro et al, 2016; Paasche, 2001; Schlüter et al, 2014). The PIC:POC ratio is a key characteristic required to understand and predict the impact of climate change on the global ocean carbon cycle (Beaufort et al, 2011; Feely et al, 2004; Gafar et al, 2019; Hutchins, 2011; Iglesias-Rodriguez et al, 2008; Schlüter et al, 2014)

Methods

Results

Discussion

Conclusion