Nanoplanktonic Protists in Marine Environments: Analysis of Natural Assemblages Using Molecualr Approaches

光养型和异养型纳米浮游原生生物（微藻和2- 20um大小的原生动物）是海洋浮游生物群落的组成部分。这些单细胞真核微生物在远洋生态系统中作为初级生产者和微消费者发挥着重要作用。目前用于列举光养纳米浮游生物（PNAN）和异养纳米浮游生物（HNAN）的方法只能提供关于这些组合的物种多样性、特定营养作用、分类特性或生物地理的粗略信息。显然需要应用新的方法来更彻底地表征PNAN和HNAN组合。分子技术和新开发的定量原位杂交方法将应用于原生生物的自然组合，以评估纳米原生生物的多样性，并鉴定和量化主要存在的纳米浮游原生生物物种。这项工作的主要重点将是从原生生物的自然组合中获得序列信息（小亚基rRNA），将这些序列与天然水样中的原生生物物种（形态物种）联系起来，并评估目标物种的丰度和分布，我们正在不断设计和测试寡核苷酸探针。这项工作将在实验的背景下进行，以检查原菌组合的物种组成变化对遏制、长期孵育（24-96小时）和富集的反应。对单个分类群种群动态的研究将开始使用为异养型金黄色单胞菌属（Paraphysomonas）和生物社会性物种自助龙单胞菌（自助龙单胞菌）开发的寡核苷酸探针和定量原位杂交方法。该项目将为利用现代分子生物学方法研究天然原生生物组合的物种多样性提供重要信息。此外，这项工作将提供一个工作模型系统，进一步完善和优化这些分子技术，用于微生物生态学的常规现场应用。

Caron NANOPLANKTONIC PROTISTS IN MARINE ENVIRONMENTS: ANALYSIS OF NATURAL ASSEMBLAGES USING MOLECULAR APPROACHES Phototrophic and heterotrophic nanoplanktonic protists (microalgae and protozoa 2-20 um in size) are integral components of marine plankton communities. These single-celled, eukaryotic microorganisms play major roles as primary producers and micro-consumers in pelagic ecosystems. Current methodologies for enumerating phototrophic nanoplankton (PNAN) and heterotrophic nanoplankton (HNAN) cannot provide more than cursory information on the species diversity, specific trophic roles, taxonomic identity or biogeography of these assemblages. There is a clear need to apply new methodologies to allow a more thorough characterization of PNAN and HNAN assemblages. Molecular techniques and a newly-developed quantitative in situ hybridization method will be applied to natural assemblages of protists in order to assess nanoprotistan diversity, and to identify and quantify the predominantly occurring nanoplanktonic protistan species. The main focus of this work will be to obtain sequence information (small subunit rRNA) from natural assemblages of protists, to relate these sequences to protistan species in natural water samples (morphospecies), and to assess the abundances and distributions of target species for which we are continually designing and testing oligonucleotide probes. This work will be conducted within the context of experiments to examine shifts in species composition of the protistan assemblage in response to containment, long-term incubation (24-96 hr), and enrichment. Work on the population dynamics of individual taxa will begin using oligonucleotide probes developed for species of the heterotrophic chrysomonad genus Paraphysomonas and the bicosoecid species Cafeteria roenbergensis, and a quantitative in situ hybridization method. The project will provide important information on the species diversity of natural protistan assemblages using modern molecular biological approaches. Additionally, this work will provide a working model system in which to further refine and optimize these molecular techniques for routine field applications in microbial ecology.