Ammonia Assimilation in the Chemoautotrophic Bacteria-Clam Symbiosis Solemya Velum

与化能自养菌的共生使一些海洋无脊椎动物，如蛤、贻贝和管虫，能够在不依赖颗粒食物的情况下生存。 相反，这些生物是自养的。 它们能够利用硫化氢作为能源，通过类似于植物光合作用的过程将二氧化碳和氨固定为有机化合物。 自养的许多生化途径定位于宿主组织的特化细胞内的细胞内共生体。 因此，这些无脊椎动物在其他不适合居住或食物匮乏的环境中茁壮成长，如深海热液喷口，冷泉和厌氧沉积物。 本项目的目标是确定导致自养代谢的生理和生化机制。 这个项目将涉及一个容易收集的沿海蛤蜊共生，Solemya velum。 以前的研究主要是在实验室中难以收集和维持的动物。 实验将集中在氨同化成有机化合物，并解决具体的问题，包括：什么是氨吸收能力的S。氨的吸收如何受环境条件的影响，什么生化途径负责同化，这些途径定位于宿主或共生体？ 这些问题将使用生物化学和分子技术相结合，以及整个生物体的生理研究，使用新设计的自动流通呼吸系统进行调查。 基于共生的自养是一个全球性的重要过程，可以支持整个生态系统，如深海喷口或珊瑚礁。 这一过程的结果是互惠主机/共生体的相互作用，没有很好地了解这些和许多其他共生系统。 更好地了解这些相互作用的性质以及它们如何影响整个群落的特征和生理机能，对于保护和管理依赖共生生物的生态系统是有价值的。 这一信息可能具有更广泛的影响，因为细菌（互利共生和寄生）与其他生物体的联系无处不在。

Symbiosis with chemoautotrophic bacteria enables some marine invertebrates, such as clams, mussels, and tubeworms, to live without relying on particulate food for their nutrition. Instead, these organisms are autotrophic. They are able to fix carbon dioxide and ammonia into organic compounds using hydrogen sulfide as an energy source via a process analogous to photosynthesis in plants. Many of the biochemical pathways of autotrophy are localized to intracellular symbionts housed within specialized cells of the host tissues. Consequently, these invertebrates thrive in otherwise inhospitable or food-poor environments such as deep-sea hydrothermal vents, cold seeps, and anaerobic sediments. The goal of this project is to determine the physiological and biochemical mechanisms that result in autotrophic metabolism. This project will involve a readily collected coastal clam symbiosis, Solemya velum. Previous studies have largely been of animals that are difficult to collect and maintain in the laboratory. Experiments will focus on assimilation of ammonia into organic compounds and address specific questions including: what are the ammonia uptake capabilities of S. velum, how is ammonia uptake affected by environmental conditions, what biochemical pathways are responsible for assimilation, and are these pathways localized to the host or symbiont? These questions will be investigated using a combination of biochemical and molecular techniques as well as whole organism physiological studies using a newly designed automated flow-through respirometry system. Symbiosis-based autotrophy is a globally important process that can support entire ecosystems such as deep-sea vents or coral reefs. This process results from mutualistic host/symbiont interactions that are not well understood in these and many other symbiotic systems. A better understanding of the nature of these interactions and how they affect the characteristics and physiology of the association as a whole can be valuable in preserving and managing ecosystems that rely on symbiotic organisms. This information potentially has even broader impacts, since association of bacteria (mutualistic and parasitic) with other organisms are ubiquitous.