EAGER: Evaluation of Dual Symbiosis in Lucinid Bivalves

在过去的三十年里，化学营养细菌和海洋双壳类之间的许多共生关系已经被确定。大多数与硫营养(硫氧化)细菌有关，但深水双壳类也报道了甲烷营养(甲烷氧化)以及硫营养细菌和甲烷营养细菌的双重共生。该实验室最近在佛罗里达和巴哈马群岛的浅海草层中发现了双壳类细菌内共生体，这表明栉孔扇贝宿主中存在双重系统。该项目将利用这些双壳类的可获得性来(1)解决与栉孔扇贝宿主的硫营养和甲烷营养细菌代谢相关的基因的系统发育，以及(2)利用这些基因组信息开发荧光原位杂交(FISH)技术、显微放射自显影技术和二次离子质谱仪的组合，以评估相同动物中内共生菌的丰度以及硫化物和甲烷的利用。这一多学科的发现不仅将提供对这种新的双壳类共生现象的洞察，而且将有可能改变共生生物学领域。由于绿藻对海草床和其他近岸海洋环境的生产力和多样性有很大影响，其丰度高达1500只/平方米，这项研究将增进对气候敏感的近岸海洋系统中甲烷循环的理解，并应对受威胁的沿海环境下的沿海资源管理决策产生广泛影响。这项研究将直接有助于为STEM地区代表性不足的妇女和少数族裔学生提供丰富的研究和教育机会。这些发现将被用来为K-12科学教育社区开发适合年级的在线科学教育模块，内容是“动物-细菌伙伴关系”。

Numerous symbiotic associations between chemotrophic bacteria and marine bivalves have been identified over the last three decades. Most are associations with thiotrophic (sulfur-oxidizing) bacteria, but methanotrophic (methane-oxidizing) and dual symbiosis of thiotrophic and methanotrophic bacteria have also been reported from deep-water bivalves. This laboratory has recently found bacterial endosymbionts in lucinid bivalves from shallow seagrass beds of Florida and the Bahamas that indicate a dual system in Phacoides pectinatus hosts. This project will take advantage of the availability of these bivalves to (1) resolve the phylogeny of genes associated with thiotrophic and methanotrophic bacterial metabolism from P. pectinatus hosts, and (2) use this genomic information to develop a combination of fluorescence in situ hybridization (FISH) technologies, microautoradiography and secondary ion mass spectroscopy to assess endosymbiont abundance and sulfide and methane utilization in the same animals. The multidisciplinary findings will not only provide insight into this novel bivalve symbiosis, but will have the potential to transform the field of symbiosis biology. Because lucinids substantially impact the productivity and diversity of seagrass beds and other nearshore marine environments, with abundances of up to 1500 individuals/m2, this research will improve understanding of methane cycling in climatically sensitive, nearshore marine systems, and should have broad implications for coastal resource management decisions in threatened coastal settings. The research will directly contribute to an enriching research and educational opportunity for women and minority students that are underrepresented in STEM areas. The findings will be used to develop online grade-appropriate science-education modules on 'animal-bacterial partnerships' for the K-12 science-education community.