Ecological Functions Of Algal Neurotoxins- Do They Interact With Ion Channels And Cellular Signaling In Non-Toxic Phytoplankton Species?

<p>Some photosynthetic unicellular marine phytoplankton species, including the marine dinoflagellates, are known to produce nuisance or harmful algal blooms (HABs) such as 'Red Tides'. Of these, several species produce toxins which, under bloom conditions, can have devastating impacts on coastal ecosystems, causing significant economic loss in fisheries and tourism of coastal communities. Moreover, the occurrence of HABs poses significant risk to public health because several human illnesses are associated with exposure to the algal neurotoxins that are produced by these bloom-forming unicellular organisms. The occurrence of HABs is thus presenting a growing global problem for fisheries, aquaculture and public health. The question of why these microscopic algae produce toxins, particularly neurotoxins, has been much debated, yet remains a poorly understood phenomenon. The harmful effects of algal neurotoxins arise because they interact with ion channels and receptors in cell membranes, interfering with conduction of nerve impulses (also known as action potentials) and signaling in animals and humans, thus leading to paralytic, amnesic and diarrhetic shellfish poisonings. Recent biophysical work has demonstrated such ion channels and action potentials are highly evolutionarily conserved, and utilized by a range of unicellular marine organisms, including diatoms, coccolithophores and dinoflagellates themselves. The hypothesis that these may be the most relevant ecological targets for HAB toxins will be investigated. The focus of this project is w on Karenia brevis, a species that produces extensive HABs in the Gulf, SE and NE USA. This dinoflagellate produces a range of toxins known as brevetoxins and researchers at the Center for Marine Sciences at the UNC-Wilmington are the world-leading experts on K. brevis and the chemistry of their toxins. In collaboration with this team, experiments will be conducted to advance understanding of why these neurochemicals are produced by dinoflagellates and whether they interact with homologous targets in competing non-toxic micro-plankton. Using a combination of cell physiology, imaging and biochemical techniques, experiments will be conducted to characterize the cellular ion currents, action potentials and calcium signals in K. brevis themselves before testing effects of brevetoxins, saxitoxins, okadaic acid and domoic acid on K. brevis and non-toxic phytoplankton. The experimental work will provide crucial insight into the sensory biology of toxin producing dinoflagellates and mechanistic insight into how their toxins interact with ecologically relevant targets in the marine ecosystem. The outcomes of this project will lead to a better understanding of the factors that regulate HAB bloom dynamics in coastal areas affected by K. brevis, may lead to development of novel biotechnological tools, and will contribute to recent national initiatives related to Oceans and Human Health.</p>