Global amphibian declines due to the fungal pathogen Batrachochytrium dendrobatidis (Bd) have led to questions about how amphibians defend themselves against skin diseases. Two amphibian defense mechanisms are antimicrobial peptides (AMPs), a component of amphibian innate immune defense, and symbiotic skin bacteria, which can act in synergy. We characterized components of these factors in four populations of Columbia spotted frogs (Rana luteiventris) to investigate their role in disease defense. We surveyed the ability of their AMPs to inhibit Bd, skin bacterial community composition, skin metabolite profiles, and presence and intensity of Bd infection. We found that AMPs from R. luteiventris inhibited Bd in bioassays, but inhibition did not correlate with Bd intensity on frogs. R. luteiventris had two prevalent and abundant core bacteria: Rhizobacter and Chryseobacterium. Rhizobacter relative abundance was negatively correlated with AMP's ability to inhibit Bd, but was not associated with Bd status itself. There was no relationship between metabolites and Bd. Bacterial communities and Bd differ by location, which suggests a strong environmental influence. R. luteiventris are dominated by consistent core bacteria, but also house transient bacteria that are site specific. Our emergent hypothesis is that host control and environmental factors shape the microbiota on R. luteiventris.

中文翻译：

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哥伦比亚斑点蛙（Rana luteiventris）具有特征性的皮肤微生物群，可能由皮肤的皮肤肽和环境形成。

由于真菌病原体Batrachochytrium dendrobatidis（Bd）造成的全球两栖动物数量下降，引发了有关两栖动物如何防御皮肤疾病的质疑。两种两栖动物防御机制是抗菌肽（AMPs）（两栖动物先天免疫防御的组成部分）和共生皮肤细菌，它们可以协同发挥作用。我们在哥伦比亚斑点蛙（Rana luteiventris）的四个种群中表征了这些因素的成分，以研究它们在疾病防御中的作用。我们调查了其AMPs抑制Bd的能力，皮肤细菌群落组成，皮肤代谢产物谱以及Bd感染的存在和强度。我们发现R. luteiventris的AMPs抑制生物测定中的Bd，但抑制与青蛙的Bd强度无关。luteiventris R.有两个普遍存在且丰富的核心细菌：根瘤菌和金细菌。根瘤菌的相对丰度与AMP抑制Bd的能力呈负相关，但与Bd的状态本身无关。代谢物和Bd之间没有关系。细菌群落和Bd的位置不同，这表明其对环境的影响很大。罗氏沼虾主要由一致的核心细菌控制，但也有特定地点的瞬时细菌。我们出现的假说是，宿主的控制和环境因素决定了R. luteiventris的菌群。