Ecological Functions of Algal Neurotoxins- do they interact with Ion Channels and Cellular Signaling in Non-toxic Phytoplankton Species?

一些具光合作用的单细胞海洋浮游植物，包括海洋甲藻，会产生滋扰性或有害的藻华，例如“红潮”。其中有几个鱼种产生毒素，在水华条件下，可对沿海生态系统产生破坏性影响，给沿海社区的渔业和旅游业造成重大经济损失。此外，有害藻华的出现对公众健康构成重大风险，因为若干人类疾病与接触这些水华形成单细胞生物产生的藻类神经毒素有关。因此，有害赤潮的出现对渔业、水产养殖和公共卫生构成了日益严重的全球性问题。为什么这些微小的藻类产生毒素，特别是神经毒素，这个问题一直在争论，但仍然是一个知之甚少的现象。藻类神经毒素之所以产生有害影响，是因为它们与细胞膜中的离子通道和受体相互作用，干扰动物和人类的神经冲动传导（也称为动作电位）和信号传导，从而导致麻痹、失忆和贝类中毒。最近的生物物理学工作表明，这种离子通道和动作电位在进化上是高度保守的，并被一系列单细胞海洋生物所利用，包括硅藻、颗石藻和甲藻本身。假设这些可能是最相关的赤潮毒素的生态目标将进行调查。该项目的重点是Karenia brevis，这是一种在墨西哥湾、美国东南部和东北部产生广泛有害生物的物种。这种甲藻会产生一系列被称为短鞭藻毒素的毒素，北卡罗来纳大学威尔明顿分校海洋科学中心的研究人员是世界领先的K。brevis及其毒素的化学性质。与该团队合作，将进行实验，以进一步了解为什么这些神经化学物质是由甲藻产生的，以及它们是否与竞争无毒微型浮游生物的同源目标相互作用。 利用细胞生理学、成像和生物化学技术的组合，将进行实验以表征K.在测试短节蛤毒素、石房蛤毒素、冈田酸和软骨藻酸对短节蛤的影响之前，短体和无毒浮游植物。实验工作将提供关键的洞察力的感觉生物学的毒素生产甲藻和机制的洞察力如何与海洋生态系统中的生态相关的目标，他们的毒素相互作用。该项目的结果将导致更好地了解在受K影响的沿海地区调节赤潮动态的因素。该项目将有助于开发新的生物技术工具，并将有助于最近与海洋和人类健康有关的国家倡议。

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.