Molecular Genetics of interactions between C. elegans and nematophagous fungi

描述（由申请人提供）：微生物在自然界中以复杂的多营养群落存在。它们依靠复杂的化学信号网络相互交流。噬线虫真菌和线虫之间的捕食关系使它们成为研究种间交流和共同进化的理想系统。我们建立了秀丽隐杆线虫和少孢单胞线虫作为模型系统来研究线虫和噬线虫真菌之间的相互作用。我发现少孢单胞螨和其他近缘种可以感知线虫的信息素、蛔虫苷，并诱导陷阱形态发生。此外，秀丽隐杆线虫被寡孢子线虫吸引，而一对嗅觉神经元（AWCs）介导了这种吸引。我建议进一步阐明控制这种相互作用的分子机制。我将通过研究A. oligospora对营养饥饿、蛔虫苷和线虫的转录调控，确定蛔虫苷感知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测序，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一步评估。为了了解AWCs如何介导寡孢单胞菌的吸引，我将通过气相色谱-质谱分析来表征吸引真菌的气味，并对AWCs进行钙成像。为了鉴定候选的化学感觉GPCRs和在真菌线索感知中起作用的下游组分，我将通过单细胞RNA-Seq分析AWC转录组。GPCR候选突变体将被评估对少孢霉气味的趋化性，而那些具有趋化性缺陷的突变体将通过钙成像进一步分析。其他awc表达的具有潜在神经元功能的基因突变体也将被筛选为对寡孢霉提取物趋化性缺陷。本研究将进一步加深我们对线虫与噬线虫真菌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策略来控制寄生线虫感染。

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.