Collaborative Research: Phylogenetics of autoresistance in poison frogs as revealed by phylogenomics, neurophysiology, and comparative ecology

动物进化出了多种化学物质来抵御捕食者。一个首要的例子是毒蛙皮肤中的有毒化学物质。因为这些青蛙颜色鲜艳，像鸟和蛇这样的捕食者学会了避开它们。这些毒素是生物碱，存在于许多动物和植物中。青蛙通过食用含有生物碱的蚂蚁和其他节肢动物来获得这些化学防御。这些蛙类生物碱（如河豚毒素、蛙毒素）具有重要的药理学意义，可引起肌肉麻痹，扰乱呼吸和心脏功能。在细胞水平上，生物碱影响控制神经冲动传递的离子通道。令人惊讶的是，毒蛙的离子通道不受自身毒素的影响；因此，破译这种进化过程对人类健康具有重要的更广泛的影响。本研究将以进化树为指导，开展天然生物碱的野外采集、鉴定和物种生态数据收集、离子通道对生物碱抗性的分子进化以及生物碱对离子通道的神经生理作用。这项研究将为德克萨斯大学和印第安纳州立大学的学生提供机会，共同参与国际实地考察，获得生物信息学、分子建模、基因组学和神经生理学方面的新技能，并促进两所大学之间的互动。该项目将使用下一代DNA转录组测序，数百个基因的靶向测序，以及生物信息学方法来重建进化树，这将指导研究计划，并提供一个实验框架来解释抗性的起源，这种抗性在毒蛙（石蛙科）中进化了多次。测序还将用于鉴定可能赋予生物碱抗性的新型氨基酸替代物。计算模型和突变离子通道的体外分析将确定这些新的替代品是否对天然和合成的生物碱具有抗性。野外工作将侧重于从多个青蛙种群中获取基因样本、皮肤生物碱和彩色照片，使用自然历史收集标准数据收集和凭证标本准备。这些方法的结合将为石蛙科毒蛙的系统学提供新的见解，也将为该群体对有毒生物碱的自身抗性的进化提供新的见解。

Animals have evolved a variety of chemicals defenses against predators. A premier example is the toxic chemicals in the skin of poison frogs. Because these frogs are brightly colored, predators such as birds and snakes learn to avoid them. These toxins are alkaloids, found in many animals and plants. The frogs acquire these chemical defenses by eating ants and other arthropods that contain the alkaloids. These frog alkaloids (e.g., tetrodotoxin, batrachotoxin) are pharmacologically important and cause muscle paralysis, and disrupt breathing and cardiac function. At the cellular level, alkaloids affect ion channels, which control the transmission of nerve impulses. Surprisingly, the ion channels of poison frogs are are not affected by their own toxins; thus, deciphering how this evolved has important broader impacts that translate to human health. This research will use evolutionary trees to guide the activities: fieldwork to acquire and characterize natural alkaloids and collect ecological data on the species, molecular evolution of ion channel resistance to alkaloids, and neurophysiological effects of alkaloids on ion channels. The research will provide opportunities for students from the University of Texas and Indiana State University to jointly participate in international fieldwork, acquire new skills in bioinformatics, molecular modeling, genomics, and neurophysiology, as well as promote interactions between the two universities.The project will use Next-Generation DNA sequencing of transcriptomes, targeted sequencing of hundreds of genes, and bioinformatics methods to reconstruct evolutionary trees that will guide the research program with an experimental framework for explaining the origin of resistance, which has evolved multiple times in the poison frogs (family Dendrobatidae). Sequencing will also be used to identify novel amino acid replacements that may confer resistance to alkaloids. Computational modeling and in vitro assays of mutated ion channels will determine if these novel replacements provide resistance to natural and synthesized alkaloids. Fieldwork will focus on acquiring genetic samples, skin alkaloids, and color photographs from multiple populations of frogs, using natural history collection standards data collection and voucher specimens preparation. The combination of approaches will provide novel insights in the systematics of Dendrobatidae poison frogs, and also the evolution of auto-resistance to toxic alkaloids within the group.