In vivo observation of lipid droplets in coral calcifying cells: fat stores to fuel the reef-building process?

Abstract

The calcifying cells of corals are responsible for skeleton formation, a process that is the basis for reef building. Their cell biology is therefore of primary interest, but current knowledge is limited because direct in vivo investigation of this cell type is challenging. Studies at the growing edge of laterally extending coral colonies allow for direct observations of actively calcifying cells in living samples. In the current study, we used this approach to study lipid droplets, which are considered storage organelles that fuel cells for physiological processes. Using the fluorescent lipid probe Nile Red and in vivo confocal microscopy, we observed lipid droplets in calcifying cells of the coral Stylophora pistillata and we suggest that they play a key role in coral calcification.