ABSTRACT
Algae are a phylogenetically diverse assemblage of organisms ranging from single-celled plankton to giant kelps. They are common in both marine and freshwater habitats. The common animal neurotransmitters acetylcholine, dopamine, histamine, phenethylamine, and serotonin occur within members of the algal Phyla Charophyta, Chlorophyta, Ochrophyta, and Rhodophyta, but not all compounds are found in all phyla. Because there are relatively few reports of these compounds in algae, discerning distributional patterns among the major algal taxa is not currently possible. The functions of neurotransmitters in algae are diverse and often unknown. In charophytes, they may be involved in the transmission of electrical signals (however, the putative transmitter, acetylcholine, has not yet been shown to occur in these algae), alleviating oxidative stresses and regulating growth. In the chlorophyte Ulvaria obscura, dopamine is synthesized in the thylakoid membranes of chloroplasts and stored in acidic vesicles. It’s only identified function is herbivore deterrence. Dopamine can also be released from U. obscura into the surrounding seawater where it may be toxic or allelopathic toward other organisms.
