Identifying cellular and molecular interactions along the pathway to symbiosis

描述(申请人提供)：这项工作的长期目标是了解在线虫(珊瑚和海葵)与光合藻之间的共生关系开始、维持和破坏时发生的细胞生物学事件。这些藻类从海水中吞噬，似乎逃避宿主的免疫反应，并改变亚细胞运输，以允许它们在细胞内持续存在。共生藻属的藻类利用阳光中的能量从二氧化碳和水中制造糖，并将高达90%的糖提供给珊瑚或海葵宿主。这种关系对珊瑚的生长至关重要，珊瑚的分解，也就是所谓的珊瑚“漂白”，可能会导致整个珊瑚礁生态系统的崩溃。这个项目考察了一个模型系统，海葵线虫和共生线虫之间的相互作用。与许多近亲不同，线虫并不是天生共生的。将在显微镜下探索线虫和共生线虫的相互作用，并使用全基因组微阵列来分析在挑战共生线虫时发生的转录变化。线虫是唯一一种拥有完整基因组序列的咸水线虫，可以详细和完整地分析其对共生线虫挑战的转录反应。这些反应将与线虫与食物或其他微生物的相互作用以及自然共生线虫与共生线虫的相互作用进行比较。转录改变的基因在自我识别与非自我识别(寄主的先天免疫反应)的进化以及细胞内运输的调节中变得非常感兴趣。最后，它们是防止珊瑚礁漂白或在珊瑚感染异源共生线虫期间抑制的潜在目标，这可能更适合当前的环境条件。被上调并可能阻止共生的基因的表达将被有选择地用吗啉抑制，其影响将在显微镜下分析。赞助实验室利用(并在许多情况下开发)了完成本提案目标所需的方法和技术，而申请人在这一领域几乎没有专业知识。申请人将接受赞助商和赞助商实验室成员(包括研究生、博士后研究员和研究助理)的培训。申请人计划在她的母校继续这个项目的方方面面。此外，她还将利用在此培训期间学到的技术，研究自然共生的海葵--苍白海葵--共生的细胞生物学。 与公共健康的相关性：这项建议分析了珊瑚礁生态系统的基础--线虫和光合藻之间的相互作用。珊瑚礁已经是大量生物医学重要化合物的来源，如果珊瑚礁生态系统在拟人化变化中幸存下来，未来很可能会发现更多的化合物。此外，分析这些生物之间的相互作用可能会深入了解其他动物(如人类)与弓形虫、疟原虫和隐孢子虫等细胞内真核寄生虫的相互作用。

DESCRIPTION (provided by applicant): The long-term objective of this work is to understand the cell biological events that occur upon the onset, maintenance and breakdown of the symbiotic relationship between cnidarians (corals and sea anemones) and photosynthetic algae. The algae are phagocytosed from seawater and appear to evade the host immune response and alter subcellular trafficking to allow their intracellular persistence. The algae, of the genus Symbiodinium, use energy from sunlight to make sugars from carbon dioxide and water, and give up to 90% of this sugar to the coral or anemone host. This relationship is essential for the growth of corals and its breakdown, known as coral "bleaching," can result in the collapse of entire reef ecosystems. This project examines the interactions between a model system, the sea anemone Nematostella vectensis, and Symbiodinium. Unlike many of its closely-related cousins, Nematostella is not naturally symbiotic. The interactions of Nematostella and Symbiodinium will be probed microscopically and by using full-genome microarrays to analyze transcriptional changes that occur upon challenge with Symbiodinium. Nematostella is the only salt-water cnidarian with full genomic sequence available, allowing a detailed and complete analysis of its transcriptional responses to challenge with Symbiodinium. These responses will be compared to the interaction of Nematostella with food or other microbes and also to the interaction of naturally symbiotic cnidarians to Symbiodinium. Genes with altered transcription become of immense interest in the evolution of self vs. nonself recognition (the innate immune response of the cnidarian host) as well as the regulation of intracellular trafficking. Finally, they represent potential targets for prevention of coral reef bleaching or for inhibition during infection of corals with heterologous Symbiodinium, which might be more suited to current environmental conditions. The expression of genes, which are up-regulated and may block symbiotic onset, will be selectively knocked down using morpholinos and the effects will be analyzed microscopically. The sponsor laboratory has utilized (and in many cases, developed) the approaches and techniques required for the completion of the goals of this proposal, while the applicant has little expertise in this area. The applicant will be trained by the sponsor and members of the sponsor's laboratory (including graduate students, post- doctoral fellows and research assistants). The applicant plans to continue aspects of this project at her home institution. Additionally, she will also utilize the techniques learned during this training period to address the cell biology of symbiosis in the naturally-symbiotic anemone, Aiptasia pallida. PUBLIC HEALTH RELEVANCE: This proposal analyzes the interaction between cnidarians and photosynthetic algae that is the basis for coral reef ecosystems. Reefs are already the source of a large number of biomedically-important compounds, and it is likely that more will be identified in the future if reef ecosystems survive anthropomorphic changes. In addition, analyzing the interaction between these organisms will likely give insight into the interaction of other animals (like humans) with intracellular eukaryotic parasites like Toxoplasma, Plasmodium and Cryptosporidium.