Marine toxic dinoflagellate release extracellular vesicles

Abstract

Effective communication between microorganisms in the marine environment is needed to mediate many ecological processes. Recent research has shown that extracellular vesicles (EVs) are produced by cyanobacteria and haptophytes and these vesicles are reported as vectors to deliver biologically active molecules involved in trophic interactions. But, little is known about the involvement of EVs in microorganism physiology and population dynamics. In this study, we explored the production of EVs by a microalgal culture of Alexandrium minutum, dinoflagellate responsible for large-scale coastal blooms and paralytic shellfish poisoning, a human disease that has adversely impacted many coastal ecosystems worldwide. The presence of EVs during the exponential phase of culture growth was assessed in isolated particles that were lipid-stained and then examined by transmission electron microscopy. Fluorescence images revealed stained vesicles, and the micrographs showed spherical vesicles (exosome-like structures) <200 nm in diameter. Our discussion addresses the potential role of EVs in population-relevant processes such as intercellular communication