Molecular Genetics of interactions between C. elegans and nematophagous fungi

描述(申请人提供)：微生物存在于自然界复杂的多营养群落中。它们依靠复杂的化学信号网络相互通信。食线虫真菌和线虫之间的捕食关系使它们成为研究物种间交流和共同进化的理想系统。我们建立了线虫和少孢线虫作为模型系统来研究线虫和食线菌之间的相互作用。我发现，少孢链霉菌和其他密切相关的物种可以感知线虫信息素、蛔虫苷，并诱导诱捕器的形态发生。此外，线虫会被寡孢菌和一对嗅觉神经元(AWCs)所吸引，这种吸引作用是由AWCs介导的。我建议进一步阐明支配这种相互作用的分子机制。我将通过研究寡孢链霉菌对营养饥饿、蛔虫苷和线虫的转录调控，鉴定其对蛔虫苷敏感和陷阱形态发生所需的基因和信号通路。我还将对其他密切相关的真菌物种的基因组进行排序，以寻找仅存在于对蛔虫苷有反应的物种中的特定受体。通过这些方法确定的候选人将通过其他功能分析进行进一步评估。为了了解AWCs如何介导寡孢子菌的吸引作用，我将通过GC-MS分析来表征诱人的真菌气味，并对AWCs进行钙成像。为了确定候选的化学感觉GPCRs和下游在感知真菌信号中发挥作用的组件，我将通过单细胞RNA-Seq来描述AWC转录本。GPCR候选的突变体将被评估对少孢霉菌气味的趋化作用，而那些具有趋化缺陷的突变体将通过钙成像进行进一步分析。其他具有潜在神经功能的AWC表达基因的突变也将被筛选出对少孢曲霉提取物的趋化缺陷。这项研究将进一步加深我们对线虫和食线虫真菌之间相互作用的分子机制的理解。在未来，这些结果将有助于开发新的方法和战略来控制寄生性线虫感染。

DESCRIPTION (provided by applicant): Microorganisms exist in complex multitrophic communities in nature. They rely on elaborate networks of chemical signaling to communicate with each other. The predator-prey relationship between nematophagous fungi and nematodes makes them an ideal system to study inter-species communication and co-evolution. We have established C. elegans and A. oligospora as a model system to study interactions between nematodes and nematophagous fungi. I found that A. oligospora and other closely-related species could sense the nematode pheromones, ascarosides, and induce trap morphogenesis. In addition, C. elegans are attracted to A. oligospora and a pair of olfactory neurons, AWCs, mediate this attraction. I propose to further elucidate the molecular mechanisms that govern this interaction. I will identify genes and signaling pathways required for ascaroside-sensing and trap morphogenesis in A. oligospora by studying its transcriptional regulation in response to nutrient starvation, ascarosides, and nematodes. I will also sequence the genomes of additional closely related fungal species to search for specific receptors that are only present in the species responding to ascarosides. Candidates identified by these approaches will be further assessed by other functional assays. To understand how AWCs mediate A. oligospora attraction, I will characterize the attractive fungal odors by GC-MS analysis and perform calcium imaging on AWCs. To identify candidate chemosensory GPCRs and downstream components that have roles in sensing fungal cues, I will profile the AWC transcriptomes by single-cell RNA-Seq. Mutants of the GPCR candidates will be assessed for chemotaxis towards A. oligospora odors and those with a chemotaxis defect will be further analyzed by calcium imaging. Mutants of other AWC-expressed genes that have a potential neuronal function will also be screened for defects in chemotaxis toward A. oligospora extract. This study will further our understanding of the molecular mechanisms that mediate interactions between nematodes and nematophagous fungi. In the future, these results will facilitate the development of new methods and strategies to control parasitic nematode infections.