LEXEN: Ecology of Microbial Systems in Extreme Environments: The Role of Nanoflagellates in Cold and Nutrient-Poor Arctic Freshwaters

在一个极端的淡水环境中，在阿拉斯加北极的一个长期研究地点，积累了大量关于微生物群落及其生态学的信息。这个和大多数其他微生物群落中最不为人所知的成员是单细胞真核生物。本项目将研究水生微生物系统的重要成员——纳米鞭毛虫的生态学、生理学和进化。将与两个获资助项目广泛合作，一个是淡水生态学项目，另一个是鞭毛虫进化项目。*随着大型生态项目的开展，这项新研究将扩展对纳米鞭毛虫在北极湖泊和池塘自然栖息地的认识，重点关注它们对寒冷和冰冻条件的适应。*将研究原生生物的多样性及其进化关系。此外，微嗜气环境将检查寻找线粒体鞭毛虫，谱系的基础知识，所有其他真核生物的基础。LExEN补充到现有的微生物系统的理解将集中在生物学和生态学的纳米鞭毛虫，水生细菌的主要捕食者。在冬季、春季、夏季和秋季，将对每年结冰的浅池塘和覆盖9个月的北极深湖的原生生物进行集中采样。结果将包括：*用显微镜和分子方法（包括针对野外样品中物种的核核体RNA探针）确定存在的纳米鞭毛虫的身份，它们的季节性丰度，分布和演代。*从rRNA序列重建这些极端环境中鞭毛虫之间的进化关系，包括沉积物的微嗜气层。这个数据库将使我们能够进一步研究这些几乎不为人知的生物。*在这种极端环境中培养的生物体的生理学，强调寒冷和冰冻对其摄食行为、呼吸和饥饿时生存的影响。这些实验将检验鞭毛虫在冷水和冰冻沉积物中生存的适应性。

In one extreme freshwater environment, a long-term research site in arctic Alaska, a large amount of information about microbial communities and their ecology has been accumulated. The least known member of this, and most other microbial communities, is the single cell eukaryotes. This LExEN project will investigate the ecology, physiology, and evolution of nanoflagellates, and important member of the aquatic microbial system. There will be extensive cooperation with two funded projects, one on freshwater ecology and one on flagellate evolution. * With the large ecological project this new research will extend knowledge of nanaflagellates in their natural habitat of arctic lakes and ponds with an emphasis on their adaptation to cold and freezing conditions. * Diversity of protists and of their evolutionary relationships will be studies. In addition, microaerophilic environments will be examined to look for amitochondriates flagellates, basic knowledge of lineages basal to all other eukaryotes. LExEN additions to this existing understanding of the microbial system will focus on the biology and ecology of the nanoflagellates, the main predator of the aquatic bacteria. Protists from a shallow pond that freezes solid each year and from a deep arctic lake with a 9-month ice cover will be intensively sampled during the winter, spring, summer and fall. Results will include: * The identity of the nanoflagellates present, their seasonal abundance, distribution, and succession with microscopic and molecular methods (including probes targeting ribosomal RNA for species in samples from the field). * The reconstruction from rRNA sequences of the evolutionary relationships among the flagellates present in these extreme environments including the microaerophilic layers of sediment. The data base will enable further research on these virtually unknown organisms. * The physiology of organisms cultured from this extreme environment with emphasis on the effects of cold and freezing on their feeding behavior and on their respiration and survival during starvation. The experiments will examine flagellate adaptations for survival in cold waters and in frozen sediments.