LEXEN: Protistan Biodiversity in Antarctic Marine Ecosystems: Molecular Biological and Traditional Approaches

*Caron 9714299极端环境微生物生物多样性的分析是困难的，因为传统的多样性检查方法往往不能有效地评估这些群落内的物种丰富度。在样本收集和处理过程中，由于难以重现和维护相关的环境特征，还出现了其他困难。本文研究了南极罗斯海海冰、沉积物和海洋环境中的原生生物组合(藻类和原生动物)。传统上，识别自然组合中的原生生物物种需要进行直接的显微分析以及用于评估生物多样性的浓缩和养殖技术。因此，由于取样、浓缩和培养以及样品保存和显微镜浓缩造成的选择性损失，这些组合的多样性容易受到偏差的影响。该项目的目标是：(1)开发和应用分子生物学方法来评估海水、海冰和沉积物环境中小型原生动物(小于100微米的藻类和原生动物)的物种多样性，以及(2)获得关于在适当温度制度下养殖的原生动物的生长速率、摄食速率和生长效率的基线生理信息。分子生物学研究将涉及使用基于聚合酶链式反应的方案来检查小亚单位核糖体RNA基因(SrDNA)的多样性。开发的方法和技术将适用于任何其他水体或沉积物，并将提供一种手段，以检查原生生物在现有养殖收藏中的代表性。***

*** Caron 9714299 The analysis of microbial biodiversity of extreme environments is difficult because traditional methods for examining diversity are often ineffective for assessing species richness within these communities. Additional difficulties arise due to the difficulties of recreating and maintaining pertinent environmental features during sample collection and procession. This study focuses on the protistan assemblages (algae and protozoa) in the sea ice, sediment and ocean environments of the Ross Sea, Antarctica. The identification of protistan species in natural assemblages traditionally has entailed direct microscopical analyses as well as enrichment and culture techniques for assessing biodiversity. Determination of diversity for these assemblages in therefore susceptible to biases as a consequence of sampling, enrichment and culture, as well as selective losses due to sample preservation and concentration for microscopy. The goals of this project are: (1) to develop and apply molecular biological approaches to assess species diversity of small protists (algae and protozoa smaller than 100 micrometers) in ocean water, sea ice and sediment environments and (2) to obtain baseline physiological information on the growth rates, feeding rates and growth efficiencies of cultured protozoa under pertinent temperature regimes. Molecular biological studies will involve the use of PCR-based protocols to examine small subunit ribosomal RNA gene (srDNA) diversity. Approaches and techniques developed will be applicable to any other water body or sediment and would provide a means to examine the representativeness of protistan cultures in extant culture collections. ***