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

光养和异养纳米浮游原生生物(微藻和原生动物大小2-20微米)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扮演着初级生产者和微型消费者的重要角色。目前对光养纳米浮游生物(PNAN)和异养纳米浮游生物(HNAN)进行计数的方法不能提供关于这些组合的物种多样性、特定营养作用、分类特征或生物地理的粗略信息。显然需要应用新的方法，以便能够更彻底地描述PNAN和HNAN的组合。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，并识别和量化主要出现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物种(形态种)联系起来，并评估我们不断设计和测试的目标物种的丰度和分布。这项工作将在实验的背景下进行，以检查原生生物组合的物种组成在围堵、长期孵化(24-96小时)和浓缩过程中的变化。将开始使用为异养菊单胞菌属和双囊藻属的物种开发的寡核苷酸探针和定量原位杂交方法来研究单个分类群的种群动态。该项目将利用现代分子生物学方法提供有关天然原生生物组合物种多样性的重要信息。此外，这项工作将提供一个工作模型系统，在其中进一步提炼和优化这些分子技术，用于微生物生态学中的常规现场应用。

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.