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

Chromist假说假设稻纵卷叶蝉、隐孢子虫和触生生物的寄主谱系是单系的，并且这三个“Chromist”组的共同祖先通过红藻的内生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倍体，除了隐单胞菌和触生寄主之间的姐妹关系。异养单细胞真核生物(原生生物)的一个小分类类群katablepharids被认为是隐单胞菌的进化近亲，而这个原生生物谱系的序列数据到目前为止还没有积累太多。目前，我们购买了两个斑头目动物的培养株，如白纹伊蚊和日本斑头虫，并正在实验室对这些细胞进行培养，以确定这两个斑头目动物的系统发育标记基因。在最初的研究项目中，我们计划ma…进一步构建这些细胞的cDNA文库，并对文库进行表达序列标签(EST)测序。遗憾的是，到目前为止还没有可用的文库，因为很难从从斑腿类细胞中提取的DNA中去除被捕食(触藻)细胞的核酸样本。然而，我们成功地从滨海乳杆菌中分离到了翻译延伸因子2(EF2)和延伸因子样基因。有趣的是，在初步的EF2系统发育中，重建了粗壮的隐头藻、隐头藻和角头藻分支，该分支进一步显示出与特德藻类和绿色植物的亲缘关系。从EF2分析得到的树状拓扑结构表明，触位体、隐单胞体和附着体确实有共同的祖先，排除了其他真核生物，并且EF2基因从植物的一个谱系横向转移到触体、隐单胞体和附属体的祖先细胞。另一方面，EFL基因的系统发育排除了触藻、隐单胞菌和海鞘类的单系，表明这三个谱系独立地从三个不同的来源获得EFL基因。较少

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