Common Principles for the Chemical Process of Inorganic Condensation in Marine Microalgae

Liquid-liquid phase separation (LLPS) is a fundamental mechanism governing intracellular organization, facilitating the formation of droplet-like structures that promote rapid and reversible condensation of proteins and nucleic acids. This process plays a crucial role in spatial organization and functional compartmentalization within cells, influencing a wide array of biological processes. Previously, we identified dense Ca-P-rich bodies within the vacuole of calcifying unicellular algae, and the results of our recent beamtime indicate that their formation is through a LLPS process. This discovery of LLPS in the formation of inorganic condensates raises questions about their prevalence in marine microalgae and prompts comparative investigations into their chemical and anatomical characteristics. We propose to examine, in addition to the data collected on Pleurochrysis carterae, two algal strains of the model species Emiliania huxleyi, both mineral-forming and non-mineralizing. Our aim with cryoSXT experiments is to image samples at different conditions of the inorganic condensates, with a focus on elucidating the dynamics of both the formation and dissolution of these inorganic structures. By using the quantitative ability of spectro-microscopy at the Ca L-edge, we will analyze the chemical compositions of intracellular ion pool. The results from these investigations will establish the role of LLPS in inorganic condensates, moving from descriptive insights into mechanistic observations of the cellular processes.