Chemical Defenses in a Toxic Dinoflagellate: Mechanisms and Constraints

智力优点：亚历山大藻属的甲藻种类分布于地球仪的各个角落，有些种类由于其毒素的产生而被认为是关键种。Alexandrum生产的化合物似乎针对不同的消费者。PST等神经毒素针对多细胞动物食草动物。在他们实验室的初步实验中，研究人员还证实了活性氧的存在，这些活性氧至少以原生生物为目标。这些化合物降低了食草动物的适应性，至少在PST的情况下，已经证明对食草动物有深远的进化影响。食草动物的适应，反过来，可以影响亚历山大种群动态。一个普遍的假设是，浮游植物中有毒化合物的产生代表了一种适应性防御。然而，支持这一假设的明确的实验证据是稀缺的。该项目将是对化学防御假说的严格实验测试。该项目的研究人员将调查一系列实验可证伪的假设与后生动物和原生动物的食草动物与亚历山大藻的挑战。该项目将提供新的理解，并深入了解，决定放牧引起的毒素生产的因素，化学防御程度和对放牧的敏感性之间的关系，以及亚历山大草中化学防御机制的成本和权衡。验证或反驳的化学防御假说是必不可少的概念模型的形成，控制和持续的有毒藻华，化学介导的捕食者-猎物的相互作用。更广泛的影响：迫切需要提高公众对公共资助的科学和世界海洋的认识。为了满足这一需求，研究人员将与专业教育工作者合作，将这项研究的结果转化为符合国家科学标准的课程材料。他们将通过其网站“捕食者和有毒猎物”向中学教育工作者提供这项研究和相关研究的结果，教育工作者将在该网站上找到可纳入高中课程的材料。调查人员还将在专门针对中学教育工作者的讲习班和专业教育工作者会议上介绍网站内容。首席调查员和他的团队将继续通过网站、非专业文章和“Aquakids”电视连续剧向非专业观众推广研究成果。本项目将培养一名博士生。学生和一个或两个本科生。 此外，拟议的工作将从事研究生和本科生在从生理学到生态和进化过程的几个研究领域。在这个过程中，这些学生将有效地研究导致适应性的新兴特性，并将这些观点应用于海洋学。

Intellectual merit: Species of the dinoflagellate genus Alexandrium occur around the globe, and some species, because of their toxin production, have been hypothesized to be keystone species. Alexandrium produces chemical compounds that appear to target different consumers. Neurotoxins such as PST target metazoan grazers. In preliminary experiments in their laboratory, the investigators also verified the presence of reactive oxygen species that target, at a minimum, protistan grazers. Such compounds reduce grazer fitness, and, at least in the case of PST, have been shown to have profound evolutionary effects on grazers. Grazer adaptation, in turn, can affect Alexandrium population dynamics. A common assumption is that production of toxic compounds in phytoplankton represents an adaptive defense. However, unequivocal experimental evidence in support of this hypothesis is scarce. This project will be a rigorous experimental test of the chemical defense hypothesis. The project's investigators will invwestigate a series of experimentally falsifiable hypotheses with both metazoan and protistan grazers challenged with Alexandrium. This project will provide novel understanding of, and insight into, the factors that determine grazer-induced toxin production, the relationship between degree of chemical defense and susceptibility to grazing, and the costs and tradeoffs of the purported mechanisms of chemical defense in Alexandrium. Verification or refutation of the chemical defense hypothesis is essential to conceptual models of the formation, control and persistence of toxic algal blooms, and chemically-mediated predator-prey interactions. Broader impact: There is an immediate and urgent need to improve the public's awareness of publicly funded science and the world's oceans. To help fill this need, the investigators will work with professional educators to translate results from this study into prepared curricular materials that meet national science standards. They will make the results of this and related studies available to secondary educators through their website "Predators and toxic prey," where educators will find materials that can be incorporated into high school curricula. The investigators also will present the website contents at workshops specifically targeted at secondary school educators, and at meetings of professional educators. The lead investigator and his team will continue to extend the results of research to lay audiences, as well, through the website, lay articles and the "Aquakids" TV series. This project will train one Ph.D. student and one or two undergraduates. In addition, the proposed work will engage graduate and undergraduate students in several areas of research from physiology to ecological and evolutionary processes. In the process, these students will effectively be studying the emergent properties that lead to adaptability and apply such perspectives to oceanography.