NSFDEB-BSF: Uneasy alliances: emergent properties and feedback mechanisms among manipulative endosymbiotic communities

看不见的微生物影响着从人类到植物到昆虫等大型生物的健康和福祉。这些微生物中有些致病，有些无害，有些有益，有时它们的作用取决于存在于同一宿主有机体中的其他微生物。这些共享同一宿主的微生物群落或“微生物组”可能非常复杂，因此很难理解不同的微生物如何相互影响和影响宿主。然而，节肢动物如昆虫和蜘蛛通常具有更简单的微生物群落，这可以作为理解微生物相互作用及其对宿主的综合影响的有用模型。此外，这些简单的微生物群落通常是可遗传的，直接从节肢动物母亲传给后代，并且可以对其宿主的生物学和繁殖产生重大影响。在这个项目中，研究人员将使用蜘蛛模型系统来研究微生物相互作用的后果。农业蜘蛛，Mermessus fradeorum，可以承载多达5株遗传细菌的社区。这些细菌以复杂的方式操纵蜘蛛的繁殖，这取决于存在哪种细菌菌株的组合。预期的研究结果将对当前和未来利用特定节肢动物宿主细菌来操纵和控制可以传播疾病的节肢动物的努力特别重要。本科学生将通过课堂活动、个人研究实验和暑期研究实习进行培训，重点是纳入代表性不足的群体。向公众的拓展将包括在学校和公共活动中面向蜘蛛的活动，包括在肯塔基大学植物园开发面向蜘蛛的探索车系列。研究人员将确定不同细菌的存在或缺失如何影响：1)宿主体内其他细菌群落成员的数量和位置，2)蜘蛛的生殖生物学结果，以及3)不同细菌群落类型在蜘蛛种群中的传播。然后，研究人员将使用数学模型对共同宿主细菌如何在共同宿主内合作与竞争做出更一般的预测。研究人员将使用抗生素对不同菌株的细菌共生体蜘蛛进行差异治疗，然后使用荧光原位杂交（FISH）显微镜和定量PCR比较其他细菌群落成员的定位和数量。通过控制交配来评估不同感染类型蜘蛛的生殖表型，以评估不同感染类型和后代性别比之间的生殖相容性。具有不同共生体群落的蜘蛛将被组装成复制的实验室种群，这些种群将被允许进化几代，以评估宿主内微生物群落对宿主与不同微生物共生体之间相互作用的影响，以及宿主种群结构是否反馈影响宿主内共生体群落的组成。分析和模拟模型将用于将共同感染细菌的宿主内相互作用与种群感染的宿主间动力学联系起来，这将为理解更复杂系统中的细菌相互作用提供一个通用框架。该提案由生物科学理事会的环境生物学和综合生物学部门共同审查和共同资助。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。

Unseen microbes influence the health and well-being of larger organisms, from humans to plants to insects. Some of these microbes cause disease, some are harmless, some are beneficial, and sometimes their effect depends on other microbes that are present in the same host organism. These microbial communities, or “microbiomes”, that share the same host can be very complicated, making it difficult to understand how different microbes affect each other and the host. However, arthropods such as insects and spiders often have simpler microbial communities that can serve as useful models for understanding microbial interactions and their combined effects on the host. Additionally, these simple microbial communities are often heritable, passed directly from arthropod mother to offspring, and can have major effects on their host’s biology and reproduction. In this project, the researchers will use a spider model system to investigate the consequences of microbe interactions. The agricultural spider, Mermessus fradeorum, can host a community of up to 5 strains of inherited bacteria. These bacteria manipulate the spider’s reproduction in complex ways that depend on which combination of bacterial strains are present. The expected research results will be particularly important for current and future efforts to use specific arthropod-hosted bacteria to manipulate and control arthropods that can transmit diseases. Undergraduate students, with an emphasis on the inclusion of underrepresented groups, will be trained through classroom activities, individual research experiments, and summer research internships. Outreach to the public will include spider-oriented events at schools and public events, including development of spider-oriented discovery cart series series at the University of Kentucky Arboretum.The researchers will determine how the presence or absence of different bacteria affect: 1) the quantity and location of other members of the bacterial community within the host’s body, 2) the resulting reproductive biology of the spider, and 3) the spread of different bacterial community types in the spider population. The researchers will then use mathematical models to make more general predictions about how co-hosted bacteria cooperate versus compete within their shared host. The researchers will use antibiotics to differentially cure spiders of various strains of bacterial symbiont, then compare localization and quantity of other bacterial community members using fluorescent in situ hybridization (FISH) microscopy and quantitative PCR. The reproductive phenotype of differentially infected spiders will be evaluated via controlled matings to assess reproductive compatibility among different infection types and offspring sex ratio. Spiders with different symbiont communities will then be assembled into replicated laboratory populations that will be allowed to evolve over several generations, to assess the effects of the within-host microbial community on interactions among hosts with different microbial symbionts, and also to whether host population structure feeds back to affect the composition of the within-host symbiont community. Analytical and simulation models will be used to tie within-host interactions of co-infecting bacteria to among-host dynamics of population infection, which will provide a generalized framework for understanding bacterial interactions in more complex systems. This proposal was co-reviewed and co-funded by the Divisions of Environmental Biology and Integrative Biology in the Directorate for Biological Sciences.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.