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

藻类神经毒素的生态功能 - 它们是否与无毒浮游植物物种中的离子通道和细胞信号相互作用？

• 批准号: 0949744
• 负责人: Alison Taylor
• 金额: $ 29.98万
• 依托单位: University of North Carolina at Wilmington
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-02-15 至 2014-01-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0949744&HistoricalAwards=false
• 关键词: Ecological; Functions; Algal; Neurotoxins; do

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.

一些光合作用的单细胞海洋浮游植物，包括海洋鞭毛藻，会产生有害的藻华，例如“红潮”。其中，一些物种产生毒素，这些毒素在开花条件下会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，有害藻华的发生对公众健康构成重大风险，因为几种人类疾病与接触由这些形成水华的单细胞生物产生的藻类神经毒素有关。因此，有害藻华的发生对渔业、水产养殖和公共卫生构成了一个日益严重的全球性问题。为什么这些微小的藻类会产生毒素，特别是神经毒素，这个问题一直有很多争论，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、失忆和腹泻性贝类中毒。最近的生物物理研究表明，这些离子通道和动作电位具有高度的进化保守性，并被一系列单细胞海洋生物利用，包括硅藻、颗石藻和鞭毛藻本身。这些可能是有害藻华毒素最相关的生态目标的假设将被调查。这个项目的重点是短凯伦氏菌，一种在海湾、美国东南部和东北部产生广泛有害藻华的物种。这种鞭毛藻会产生一系列被称为短链菌毒素的毒素，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短链菌及其毒素化学方面的世界领先专家。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鞭毛藻产生的，以及它们是否与竞争无毒微型浮游生物中的同源靶标相互作用。结合细胞生理学、成像和生化技术，在测试短叶藻毒素、蛤蚌毒素、冈田酸和软骨藻酸对短叶藻和无毒浮游植物的影响之前，将进行实验，以表征短叶藻本身的细胞离子电流、动作电位和钙信号。这项实验工作将为产生毒素的鞭毛藻的感觉生物学以及它们的毒素如何与海洋生态系统中生态相关目标相互作用的机理提供重要的见解。该项目的成果将有助于更好地了解在受短角镰刀藻影响的沿海地区调节藻华繁殖动态的因素，可能导致开发新的生物技术工具，并将有助于最近有关海洋和人类健康的国家举措。