Phylogenetic and morphological differences of Arctic and Antarctic choanoflagellates

异养纳米鞭毛虫在南极和北极海洋生态系统中起着非常重要的作用。在这些原生生物中，领鞭毛虫是南极和北极海洋微型浮游生物的一个显著而丰富的组成部分。虽然已经发表了一些关于领鞭毛虫的定量和定性研究，但最近对海洋微型动物的分子生物学研究表明，对这些微小生物（3-6微米细胞大小）的形态学研究显示，分类分辨率有限。然而，到目前为止，只有大约三个海洋choanoflagellate物种已测序（18 S rDNA）。在拟议的项目期间，将获得纳米原生生物的培养物，结合形态学和分子生物学方法对其进行分析，并获得有关这些高度可变的原生生物分布的信息。我们想解决以下问题：在北极和南极沃茨发现的领鞭毛虫的分子身份是什么？是否存在具有相同18 SrDNA带型的南极领鞭藻种，表明其具有全球性分布？如何可变的是18 S rDNA基因和部分序列可以用来开发一种可靠的海洋choanoflagellates的定量和定性分析的方法？对领鞭毛虫的进一步研究1）作为后生动物的姐妹群，从生殖发生的角度来看将是非常有趣的，2）作为远洋食物网基础上的一个非常有生产力的群体，将对更广泛地了解极地地区的生态过程特别感兴趣。

Heterotrophic nanoflagellates play a very important role in marine Antarctic and Arctic ecosystems. Among these protists, choanoflagellates form a conspicuous and abundant component of the Antarctic and arctic marine nanoplankton. Although a number of quantitative and qualitative studies have been published on choanoflagellates, recent molecular biological studies of marine nanofauna indicated that morphological investigations of these tiny organisms (3-6µm cell size) reveal only limited taxonomic resolution. However, until now only about three marine choanoflagellate species have been sequenced (18S rDNA). During the proposed project will acquire cultures of nanoprotists, analyse them combining morphological and molecular biological methods and to receive information on the distribution of these highly variable protists. We would like to address the following questions: What is the molecular identity of choanoflagellates found in Artic and Antarctic waters? Do there exist Antarctic choanoflagellate species with the same 18S rDNA pattern indicating a global distribution? How variable is the 18S rDNA gene and can parts of the sequence be used to develop a method for reliable quantitative and qualitative analyses of marine choanoflagellates? Further research on choanoflagellates 1) as a sister group of metazoans would be very interesting from the viewpoint of phylogeny and 2) as a very productive group at the basis of the pelagic food web would be of special interest for a broader understanding of ecological processes in polar regions.