NSF Postdoctoral Fellowship in Biology FY 2020

该行动资助了NSF 2020财年生物学博士后研究奖学金，研究基因组，环境和表型之间相互作用的生命规则的综合研究。该奖学金支持将以创新方式为《生活规则》领域作出贡献的研究员的研究和培训。以植物为食的昆虫占陆生动物种类的绝大多数，其中大多数专门食用少数几种植物。因此，了解昆虫寄主的专门化对了解地球上生命的多样性非常重要。关于寄主专门化盛行的一种假设是，它允许昆虫将有毒的寄主植物化学物质吸收到自己的组织中。这个过程被称为隔离，并有助于赋予化学介导的保护，以抵御捕食者和病原体。在昆虫中最著名的是黑脉金斑蝶（Danaus plexippus），它的幼虫以含有有毒化学物质的马利筋植物为食，这些化学物质使它们对捕食者感到厌恶。虽然黑脉金斑蝶的吸收量已经被研究过了，但与硬核内酯吸收和运输有关的基因仍然未知，而且也不清楚黑脉金斑蝶吸收量硬核内酯的能力是马利筋寄主植物专门化的原因还是结果。这项研究将回答这些关于君主的基本问题，同时涉及来自代表性不足群体的本科生；教育研讨会将鼓励公民科学实践。下面的方法将把基因变异（ATPα1结合域，转运体）与影响帝王蝶与环境相互作用方式的表型变异（隔离能力）联系起来。在第一种方法中，研究员将利用两种马利筋物种的果仁内酯含量的自然变化和帝王蝶种群隔离果仁内酯能力的自然变化。通过实验饲养和基因表达分析，研究员将确定参与核桃内酯运输和储存过程的基因，以及这些基因在宿主、黑脉金斑蝶种群和发育阶段的表达差异。在第二种方法中，研究员将使用“逆向进化”来了解哪个先进化：君主的目标位点对核苷不敏感还是有能力隔离核苷。该研究员将使用基因编辑技术（CRISPR-Cas9）将一系列逐步突变引入到cardenolide靶位点（Na+/K+- atp酶），以确定在cardenolide敏感背景下是否仍有可能进行隔离。该研究员将获得分子生物学、化学生态学和生物信息学方面的宝贵培训，并通过将黑脉金斑蝶幼虫监测计划扩大到波多黎各进行推广。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

This action funds an NSF Postdoctoral Research Fellowship in Biology for FY 2020, Integrative Research Investigating the Rules of Life Governing Interactions Between Genomes, Environment and Phenotypes. The fellowship supports research and training of the Fellow that will contribute to the area of Rules of Life in innovative ways. Insects that eat plants comprise the vast majority of terrestrial animal species, and most specialize on a small number of plant species. Understanding host specialization in insects is thus important for understanding the diversity of life on Earth. One hypothesis for the prevalence of host specialization is that it allows insects to incorporate toxic host plant chemicals into their own tissues. This process is known as sequestration and helps to confer chemically-mediated protection against predators and pathogens. Sequestration in insects is best-known from the monarch butterfly (Danaus plexippus), whose larvae feed on milkweed plants containing toxic chemicals (cardenolides) that make them distasteful to predators. Although monarch sequestration has been studied, the genes involved in cardenolide uptake and transport remain unknown, and it is also unclear whether the monarch’s ability to sequester cardenolides is a cause or a consequence of specializing on milkweed host plants. This research will answer these basic questions about monarchs while involving undergraduates from underrepresented groups in this investigation; educational workshops will encourage the citizen science practices. The approaches below will link variation in genes (ATPα1 binding domain, transporters) to variation in a phenotype (sequestration ability) that affects the way that monarchs interact with their environment. In the first approach, the Fellow will leverage natural variation in cardenolide content of two milkweed species and natural variation in the ability of monarch populations to sequester cardenolides. Using experimental rearing and gene expression analysis, the Fellow will determine the genes involved in the process of cardenolide transport and storage, and how these genes differ in expression across hosts, monarch populations, and developmental stages. In the second approach, the Fellow will use “evolution-in-reverse” to understand which evolved first: the monarch’s target site insensitivity to cardenolides or the ability to sequester cardenolides. The Fellow will use gene-editing techniques (CRISPR-Cas9) to introduce a series of stepwise mutations into the cardenolide target site (the Na+/K+-ATPase) to determine whether sequestration is still possible on a cardenolide-sensitive background. The Fellow will gain valuable training in molecular biology, chemical ecology, and bioinformatics as well as in outreach by expanding the Monarch Larvae Monitoring Program to Puerto Rico.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.