Glutamate as an extracellular signalling molecule in unicellular protists

elevations were specific to glutamate, with little or no response to a range of other amino acids. Glutamate sensing was partially disrupted by domoic acid, a toxic analogue of glutamate produced by some harmful diatom species. The cellular role of extracellular glutamate sensing in diatoms remains to be elucidated, although the ability to sense this abundant amino acid may represent a mechanism that allows unicellular eukaryotes to detect wounding of neighbouring cells within a population. Our findings support a widespread role for glutamate as an extracellular signalling molecule in unicellular eukaryotes that likely enabled the emergence of complex glutamate-dependent signalling networks in multicellular organisms.