Chemical imaging of a Symbiodinium sp. cell using synchrotron infrared microspectroscopy: a feasibility study

Summary The symbiotic relationship between corals and Symbiodinium spp. is the key to the success and survival of coral reef ecosystems the world over. Nutrient exchange and chemical communication between the two partners provides the foundation of this key relationship, yet we are far from a complete understanding of these processes. This is due, in part, to the difficulties associated with studying an intracellular symbiosis at the small spatial scales required to elucidate metabolic interactions between the two partners. This feasibility study, which accompanied a more extensive investigation of fixed Symbiodinium cells (data unpublished), examines the potential of using synchrotron radiation infrared microspectroscopy (SR‐IRM) for exploring metabolite localisation within a single Symbiodinium cell. In doing so, three chemically distinct subcellular regions of a single Symbiodinium cell were established and correlated to cellular function based on assignment of diagnostic chemical classes. Lay description The symbiotic relationship between corals and their algal symbionts is the key to the success and survival of coral reef ecosystems the world over. Nutrient exchange and chemical communication between the two partners provides the foundation of this key relationship, yet we are far from a complete understanding of these processes. This is due, in part, to the complexity of studying the tiny algal symbiont while it resides within the coral tissue; the symbiont is approximately 1/100th of a millimetre in diameter. Here, we examine the potential of using infrared light to determine the location of metabolites within a single symbiont and in doing so, have identified three regions of biological activity that highlights the potential of this technique.