Testing the Chromist monophyly based on multi-gene phylogenetic analyses considering the sequence data from katablepharids.

发色假说认为层虫、隐单胞虫和附生植物的寄主谱系是单系的，这三种“发色”类群的共同祖先通过红藻的内共生捕获了含有叶绿素a + c的质体。到目前为止，基于核编码基因的分子系统发育分析还没有从整体上恢复染色体单系，除了隐单胞菌和附胚寄主谱系之间存在强大的姐妹关系。一个小的异养单细胞真核生物（原生生物）分类群，katablepharids，被认为是隐单胞虫的进化近亲，然而这个原生生物谱系的序列数据迄今为止还没有积累多少。我们目前购买了两个katablepharids的培养菌株，如Leucocyrptos marina和katablepharids japonica，并正在我们的实验室培养这些细胞，以确定这两个katablepharids系统发育的标记基因。在最初的研究项目中，我们计划建立这些细胞的cDNA文库，并对文库进行EST测序。遗憾的是，由于从katablephids细胞中提取的cDNA很难去除猎物（haptophyte）细胞的核酸样本，目前还没有相应的文库。然而，我们成功地从L. marina中分离到了翻译伸长因子2 （EF2）和伸长因子样基因。有趣的是，在EF2的初步系统发育中，我们重建了强壮的触生动物、隐殖动物和食肉动物的进化支，该进化支进一步显示出与绿藻和绿色植物的亲和力。从EF2分析中获得的树状拓扑结构表明，除了其他真核生物外，触觉细胞、隐单胞体和表咽细胞确实具有共同的祖先，并且EF2基因是从属于植物的一个谱系中横向转移到触觉细胞、隐单胞体和表咽细胞的祖先细胞中。另一方面，EFL基因的系统发育拒绝了单系性，暗示这三个谱系独立地从三个不同的来源获得EFL基因。少

The Chromist hypothesis assumes the host lineages of stramenopiles, cryptomonads, and haptophytes are monophyletic, and a common ancestor of the three "chromist" groups had captured plastids containing chlorophyll a plus c through an endosymbiosis of a red alga. So far, molecular phylogenetic analyses based on nucleus-encoded genes have not recovered the Chromist monophyly as a whole, except a robust sister relationship between cryptomonad and haptophyte host lineages.A small taxonomic group of heterotrophic unicellular eukaryotes (protists), katablepharids, has been considered as an evolutionary relatives of cryptomonads, whereas the sequence data of this protist lineage has not much accumulated to date. We currently purchased two culture strains of katablepharids, such as Leucocyrptos marina and Katablepharids japonica, and are culturing these cells in our laboratory to determine marker genes for phylogeny from the two katablepharids. In the initial research project, we planned to ma … More ke a cDNA library for these cells, and conduct expressed sequence tags (EST) sequencing on the libraries. Unfortunately, no library is available so far, since it is difficult to eliminate the nucleic acid sample of prey (haptophyte) cells from the cDNA extracted from katablepharids cells. However, we successfully isolated translation elongation factor 2 (EF2) and elongation factor-like genes from L. marina. Interestingly, the robust, clade of haptophytes, cryptomonads, and katablepharids was reconstructed in a preliminary EF2 phylogeny, and this clade further showed affinity to ted algae and green plants. This tree topology obtained from the EF2 analysis suggests that haptophytes, cryptomonads, and katablepharids indeed share a common ancestry to the exclusion of other eukaryotes, and the EF2 gene was laterally transferred from a lineage belong to the Plantae to the ancestral cells of haptophytes, cryptomonads, and katablepharids. On the other hand, phylogenetic of EFL genes reject the monophyly of haptophytes, cryptomonads, and katablepharids, indicating that the three lineages independently acquired EFL genes from three distinctive sources. Less