Identifying cellular and molecular interactions along the pathway to symbiosis

描述（由申请人提供）：这项工作的长期目标是了解刺胞动物（珊瑚和海葵）与光合藻类之间共生关系的开始、维持和破坏时发生的细胞生物学事件。藻类从海水中被吞噬，似乎可以逃避宿主的免疫反应，并改变亚细胞运输以使其在细胞内持续存在。这种共生藻类利用来自阳光的能量从二氧化碳和水中制造糖，并将其中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，而这种关系的破裂，即所谓的珊瑚“白化”，可能导致整个珊瑚礁生态系统的崩溃。这个项目研究了一个模型系统，海葵Nematostella vectensis和共生菌之间的相互作用。不像它的许多近亲，线虫不是天然共生的。Nematostella和Symbiodinium的相互作用将在显微镜下进行探测，并通过使用全基因组微阵列来分析Symbiodinium挑战时发生的转录变化。Nematostella是唯一具有完整基因组序列的海水刺胞动物，允许对其对共生菌挑战的转录反应进行详细和完整的分析。这些反应将与线虫菌与食物或其他微生物的相互作用以及天然共生刺胞菌对共生菌的相互作用进行比较。转录改变的基因在自我与非自我识别的进化（刺胞宿主的先天免疫反应）以及细胞内运输的调节中变得非常有趣。最后，它们代表了防止珊瑚礁白化或抑制异源共生菌感染珊瑚的潜在目标，这可能更适合当前的环境条件。使用morpholinos选择性地敲除被上调并可能阻断共生发生的基因的表达，并在显微镜下分析其影响。赞助实验室已经利用（并且在许多情况下，开发）完成该提案目标所需的方法和技术，而申请人在该领域几乎没有专业知识。申请人将由主办方及其实验室成员（包括研究生、博士后和研究助理）进行培训。申请人计划在她的家乡机构继续这个项目的各个方面。此外，她还将利用在培训期间学到的技术来解决自然共生海葵（Aiptasia pallida）的共生细胞生物学问题。

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.