Physiological Adaptions for a Deadly Diet: Bioaccumulation Mechanisms of Defensive Chemicals in a Poison Frog

致命饮食的生理适应：毒蛙中防御性化学物质的生物累积机制

• 批准号: 1822025
• 负责人: Lauren O'Connell
• 金额: $ 47.19万
• 依托单位: Stanford University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2017
• 资助国家: 美国
• 起止时间: 2017-12-06 至 2020-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1822025&HistoricalAwards=false
• 关键词: Physiological; Adaptions; Deadly; Diet; Bioaccumulation

South American poison frogs are brightly colored and highly toxic, advertising their unpalatabilily to potential predators. Poison frogs do not make these toxins themselves, but instead acquire toxins from the ants and mites they consume in their diet. Although scientists have long known that poison frogs accumulate toxins from their diet, how the frogs accumulate the toxic chemicals is unknown. The goal of this research is to understand how poison frogs accumulate and move toxins from the gut through the liver and to the skin for storage. Describing this process will increase our knowledge of how animals have evolved special physiological mechanisms to acquire new resources from their environment. As many of these toxins and other frog chemicals are small molecules similar to many pharmaceutical drugs, understanding how poison frogs transport these chemicals may yield more general insights about how this process is different from other animals (including mammals), which cannot accumulate these compounds. This research will provide learning experiences to all age groups in both the United States and in Ecuador, where fieldwork on poison frogs will be conducted. This award is co-funded by the NSF Office of International Science and Engineering. Research will be incorporated into science K-12 classrooms through the Little Froggers School Program, which teaches children about ecology and evolution. High school biology teachers will be involved in fieldwork in Ecuador and will incorporate their research findings into their science curriculum. This research will also involve training of undergraduate, graduate, and postdoctoral students in chemistry, ecology, proteomics, and bioinformatics.Poison frogs acquire chemical defenses from dietary arthropods and have evolved specialized physiological adaptations for toxin bioaccumulation and modification. Although sequestering defensive chemicals is one component of well-studied ecological and evolutionary relationships between arthropod prey and frog predators, the mechanisms used by poison frogs to sequester and modify toxins are largely unknown. The overall goal of this research is to understand the physiological mechanisms of toxin bioaccumulation in poison frogs through three aims: 1) Identify proteins involved in bioaccumulation of dietary toxins in the Little Devil frog using thermal proteome profiling. 2) Determine toxin pharmacokinetics in distinct genetic backgrounds of the Little Devil frog using captive feeding experiments and liquid chromatography mass spectrometry across several time points. 3) Test the hypothesis that different Little Devil frog populations have local adaptations to efficiently accumulate chemicals found in local arthropod prey by characterizing population differences in toxin-binding protein abundance using tandem liquid chromatography mass spectrometry. Together, this work will test whether variation in toxin-binding protein levels is due to genetic differences between populations, response to dietary toxin availability, or a combination of both genetic and environmental contributions. This research will more broadly add to the knowledge of how ecological resources shape animal physiology.

南美洲的毒蛙颜色鲜艳，毒性很强，这让潜在的捕食者很难接受。毒蛙本身并不制造这些毒素，而是从它们的饮食中摄入的蚂蚁和螨虫中获得毒素。虽然科学家早就知道毒蛙会从食物中积累毒素，但它们是如何积累有毒化学物质的却不得而知。这项研究的目的是了解毒蛙如何积累和移动毒素从肠道通过肝脏和皮肤储存。描述这一过程将增加我们对动物如何进化出特殊的生理机制以从环境中获得新资源的知识。由于这些毒素和其他青蛙化学物质中的许多都是类似于许多药物的小分子，了解毒蛙如何运输这些化学物质可能会产生更一般的见解，了解这个过程与其他动物（包括哺乳动物）的不同之处，这些动物不能积累这些化合物。这项研究将为美国和厄瓜多尔的所有年龄组提供学习经验，在那里将进行关于毒蛙的实地调查。该奖项由NSF国际科学与工程办公室共同资助。研究将通过小青蛙学校计划纳入科学K-12教室，该计划教授儿童生态学和进化论。高中生物教师将参与厄瓜多尔的实地考察，并将其研究成果纳入科学课程。这项研究还将涉及培养本科生、研究生和博士后学生在化学、生态学、蛋白质组学和生物信息学方面的能力。毒蛙从节肢动物的食物中获得化学防御能力，并进化出专门的生理适应能力，以进行毒素的生物积累和修饰。虽然隔离防御化学物质是节肢动物猎物和青蛙捕食者之间的生态和进化关系的一个组成部分，但毒蛙隔离和修改毒素的机制在很大程度上是未知的。本研究的总体目标是通过三个目标来了解毒素在毒蛙体内生物积累的生理机制：1）利用热蛋白质组分析技术鉴定与毒蛙体内食物毒素生物积累有关的蛋白质。2)确定毒素的药代动力学在不同的遗传背景下的小魔鬼蛙使用圈养饲养实验和液相色谱质谱在几个时间点。3)测试的假设，不同的小魔鬼蛙种群有当地的适应，有效地积累在当地的节肢动物猎物中发现的化学物质，通过表征人口差异的毒素结合蛋白丰度，使用串联液相色谱质谱。总之，这项工作将测试毒素结合蛋白水平的变化是否是由于人群之间的遗传差异，对饮食毒素可用性的反应，或遗传和环境贡献的组合。这项研究将更广泛地增加生态资源如何塑造动物生理学的知识。