CAREER: Connecting behavioral phenomes with functional genomes in ants, manipulated by a fungal parasite

受感染的动物的行为通常与健康的动物不同。这些变化可以超越单纯的疾病行为，反映寄生虫诱导的精确操纵，以增加寄生虫传播的机会。目前尚不清楚操纵性寄生虫如何改变宿主的行为。行为上易于处理的“僵尸蚂蚁系统”有可能揭示寄生行为操纵的潜在机制，并从根本上改变人们对寄生虫-宿主相互作用及其行为生态效应的看法。该项目使用真菌感染的“僵尸蚂蚁”作为模型，系统地量化疾病的进展和伴随的行为表型，以确定疾病行为在哪里结束，操纵从哪里开始，以及涉及哪些复杂的分子机制。了解昆虫行为的规律以及如何有效地干扰它，可以用在进化上更强大的方法来与害虫作斗争。此外，所发现的新型真菌效应器在人类医学中具有潜在的应用前景。该项目将利用公众对制造僵尸寄生虫的兴趣，创建身临其境的教学方法，向不同的学生群体教授生物学。因此，研究人员将开发一种基于研究的、关于微生物感染和昆虫的教育虚拟现实体验，带到K-12学校、博物馆和博览会。在一所大型、种族和社会经济多元化的大学，本科生将有机会通过一门关于昆虫行为和操纵的密集研究课程，参与到科学进程中来。多名研究生和本科生也将参与这个项目的综合研究活动，为他们为日益跨学科的STEM就业市场做好准备。这项研究旨在1)研究蚂蚁在感染过程中行为如何变化；2)蚂蚁和真菌组织在整个过程中如何相互作用；3)揭示来自寄生虫和宿主的哪些基因和途径导致行为表型；以及4)阐明这些基因和途径的确切功能。这项工作跨越了多种技术方法的整合，以了解蛇虫夏草属的僵尸制造真菌如何从分子水平到整个有机体所显示的行为输出与蚂蚁相互作用。被蛇口虫草感染的蚂蚁被操纵攀爬和咬人，是僵尸制造者中常见的行为表型。因此，回答这些真菌寄生虫是如何改变宿主行为途径的，也将为其他模型系统中的机械性假设提供跳板。具体地说：1)比较感染研究和可量化的行为分析将揭示正常行为如何从单纯的疾病表型发展到寄生虫适应操纵表型。2)整个蚂蚁的三维X射线显微断层扫描模型将显示真菌细胞在整个疾病发展过程中如何与蚂蚁组织物理相互作用。3)混合RNA-Seq将提供两种生物的伴随基因表达谱，这些基因表达谱是这些详细的形态和行为表型的基础。这将导致发现新的真菌效应器，以及它们潜在的目标昆虫途径。4)对感兴趣的真菌效应器进行基因改造，然后对这些改良菌株或其产生的化合物进行功能行为分析，将揭示它们的真实功能和参与操纵宿主行为。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Infected animals generally behave differently from healthy animals. These changes can go beyond mere sickness behaviors to reflect precise manipulations induced by parasites to increase that parasite’s chances to spread. How manipulative parasites can alter host behavior is currently unknown. The behaviorally tractable “zombie ant system” has the potential to expose the mechanisms underlying parasitic behavioral manipulation and fundamentally transform perceptions of parasite-host interactions and their behavioral ecology effects. This project uses fungus-infected “zombie ants” as a model to systematically quantify disease progression and accompanying behavioral phenotypes, to determine where sickness behavior ends, where manipulation begins, and which intricate molecular mechanisms are involved. Knowledge of the regulation of insect behavior and how to effectively disrupt it can be used in evolutionarily more robust methods to battle pests. Additionally, the novel fungal effectors discovered are potentially applicable in human medicine. The project will leverage the public’s interest in zombie-making parasites to create immersive pedagogies for teaching biology to a diverse student population. As such, the investigators will develop a research-based, educational virtual reality experience about microbial infections and insects to take to K-12 schools, museums and fairs. Undergraduate students at a large, ethnically and socio-economically diverse university will get the opportunity to involve themselves in the scientific process through a research-intensive course on insect behavior and manipulation. Multiple graduate and undergraduate students will also be involved in the integrative research activities of this project, preparing them for an increasingly cross-disciplinary STEM job market.The research seeks to 1) examine how ant behavior changes throughout infection; 2) how ant and fungal tissues interact throughout this progression; 3) reveal which genes and pathways from both parasite and host give rise to behavioral phenotypes; and 4) elucidate the exact functions of these genes and pathways. The work spans the integration of multiple technological approaches to understand how zombie-making fungi of the genus Ophiocordyceps interact with ants from the molecular level to the behavioral output displayed by the whole organism. Manipulated climbing and biting of Ophiocordyceps-infected ants represent common behavioral phenotypes among zombie makers. Thus, answering how these fungal parasites modify host behavioral pathways will also form a springboard for mechanistic hypotheses in other model systems. Specifically: 1) Comparative infection studies and quantifiable behavioral assays will reveal how normal behavior progresses beyond mere sickness phenotypes to parasite-adaptive manipulation phenotypes. 2) Three-dimensional X-ray microtomography models of whole ants will show how fungal cells physically interact with ant tissues throughout the disease progression. 3) Mixed RNA-Seq will provide accompanying gene expression profiles of both organisms that underlie these detailed morphological and behavioral phenotypes. This will lead to the discovery of novel fungal effectors, and the insect pathways they potentially target. 4) The genetic modification of fungal effectors of interest, followed by functional behavioral assays with those modified strains or their produced compounds, will expose their true function and involvement in the manipulation of host behavior.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.