Collaborative Research: Defining the role of skin microbiomes in defense against chytridiomycosis in frogs with seasonal infections

微生物群是包括皮肤在内的所有生态系统中无处不在的一部分。尽管“好”微生物可以抵御病原体的观点被广泛接受，但尚不清楚微生物群落如何在可变气候条件下为宿主提供益处。这项研究将研究一种致命的皮肤真菌的防御机制，这种真菌与全球两栖动物的衰落有关。这些研究将调查天然皮肤微生物和青蛙免疫力之间的联系，以了解疾病结果的季节性变化，使用一种可能死于感染但可以在最佳环境条件下存活的青蛙。该项目解决了疾病易感性和免疫之间的相互作用，这些物种没有自由生活的蝌蚪阶段，而是直接发育的青蛙。考虑到当前天气模式的变化，季节性预计会随着时间的推移而变化，从而增加了宿主-病原体关系的不稳定性。为了研究皮肤中的微生物群如何与对这种病原体的免疫反应相互作用，研究人员将在自然种群中研究青蛙，并进行对照实验室实验。这一结果将有助于更好地预测季节变化对物种相互作用的影响，从而影响对新出现疾病的防御。研究人员将为大学水平的疾病生态学课程开发和传播课程材料，该课程整合了从生态学和进化以及从分子水平到生态系统影响的基本概念。此外，研究人员将与佛罗里达自然历史博物馆合作，针对中学生开展有关两栖动物疾病生态学和微生物组的拓展旅游展览。壶菌病是一种由壶菌引起的真菌疾病，在全球范围内对两栖动物构成威胁，宿主通常生活在低和高病原体风险的动态循环中。这一建议将重点放在直接发育的蛙类伊柳棘足猴上，这是一种在野外生存的物种，感染由非生物因素和微生物群落调节。研究人员将测试宿主免疫防御是否通过调节某些细菌成员的存在/缺失与皮肤微生物群相互作用，从而影响对真菌感染的易感性。研究人员将在野外和实验室中收集微生物群落（即具有不同群落结构的假定共生体分组），以量化宿主免疫防御，包括本构免疫和适应性反应。该提案包括三个研究目标：1)表征种群水平的皮肤细菌季节性联盟，皮肤分泌物中的免疫防御及其相互作用；2)测试不同细菌多样性背景下宿主防御的再分配；3)测量假定共生体、宿主皮肤防御和由此产生的病原体负担的生命阶段变异性。该项目将利用来自宿主防御和微生物分析、微生物组扩增子测序和功能基因组学的个人水平数据来评估反应的时间和程度。通过不同环境条件下宿主皮肤防御的视角，对皮肤微生物组进行综合研究，将揭示环境、免疫和微生物组在疾病抵抗和耐受中的作用。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。

Microbiomes are a ubiquitous part of all ecosystems including the skin. Although the idea that “good” microbes can defend against pathogens is widely accepted, it is still unclear how microbial communities provide benefits to the host under variable climates. This research will examine the defense mechanisms against a lethal skin fungus that has been associated with global amphibian declines. The studies will investigate the links between natural skin microbes and frog immunity to understand seasonal changes in disease outcomes using a species of frog that can die of infection but can survive under optimal environmental conditions. This project addresses the interplay between disease susceptibility and immunity for species that do not have a free-living tadpole stage but instead are direct-developing frogs. Considering the current changes in weather patterns, seasonality is expected to shift over time, adding more instability to host-pathogen relationships. To address how microbiomes in skin interact with the immunological response to this pathogen, the researchers will study frogs in natural populations and perform controlled laboratory experiments. The results will allow better predictions about the impact of seasonal variations on species interactions that can influence defense against emerging diseases. The researchers will develop and disseminate course materials for a college-level Disease Ecology course that integrates fundamental concepts from ecology and evolution and from the molecular level to ecosystem impacts. In addition, the researchers will work with the Florida Museum of Natural History to develop outreach travel exhibitions targeted to middle schoolers about amphibian disease ecology and microbiomes. Amphibians are globally threatened by chytridiomycosis, a fungal disease caused by Batrachochytrium dendrobatidis, and hosts often live under dynamic cycles of low and high pathogen risk. This proposal will focus on the direct-developing frog, Eleutherodactylus coqui, a species that persists in the wild with infections modulated by abiotic factors and microbial communities. The researchers will test if host immune defenses interact with skin microbiome by regulating the presence/absence of certain bacterial members, in turn influencing susceptibility to fungal infection. The researchers will assemble sets of microbial consortia (i.e., groupings of putative symbionts with different community structures) to quantify host immune defenses including constitutive immunity and adaptive responses in the field and in the lab. The proposal includes three research objectives: 1) characterize population-level seasonal consortia of skin bacteria, immune defenses in the skin secretions, and their interactions, 2) test for the redistribution of host defenses under contrasting backgrounds of bacterial diversity, and 3) measure life-stage variability in putative symbionts, host skin defenses, and resulting pathogen burden. The project will leverage individual-level data from host defenses and microbiological assays, microbiome amplicon sequencing, and functional genomics to evaluate the timing and magnitude of responses. Integrated studies of skin microbiomes seen through the lens of host skin defenses under different environmental conditions will shed light on the role of the environment, immunity, and microbiome in resistance and tolerance to disease.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.