Early evolution of eukaryotes inferred by combined phylogeny of multiple genes

为了阐明真核生物的高级系统发育，推断真核生物的一个树根，进行了多基因的联合系统发育。为此，从草履虫、蜂窝虫、中心虫、隐单胞虫、视紫藻属和独角藻等各种生物中分离并测序了编码胞质核糖体RNA和保守蛋白的几个基因。包括获得的原始序列数据，生成具有不同分类单元样本和不同基因选择的各种数据集，并对这些数据集进行多基因的联合最大似然分析。直到最近，已经取得了以下主要成果：1.通过不同的数据集独立地获得了将着丝点定位在Bikont生物体的外群位置以及位于变形虫和后生动物的分支之间的最佳树木，但这些位置没有明显的统计可信度。没有得到明确的支持，包括隐芽植物、隐芽植物、草本植物和肺泡细胞。伸长因子1α和2的系统发育分析表明，短毛异尖线虫和与短毛滴虫相似的鞭毛虫(NY0173)位于滴虫和鞭毛虫的分支之间，支持基于SSUrRNA系统发育的结果。

In order to elucidate a higher-order phylogeny of eukaryotes infer a root of the eukaryotic tree, combined phylogeny of multiple genes were carried out. For this purpose, several genes encoding cytosolic ribosomal RNAs and conservative proteins were isolated and sequenced from various organisms belonging to stramenopiles, alveolates, centrohelids, cryptomonads, rhodophytes, and fornicates. Including original sequence data obtained, various kinds of data sets with different taxon samplings and with different selections of genes were generated and these were analyzed by combined maximum likelihood analyses of the multiple genes. Until recently major outcomes listed below have been obtained:1. Optimal trees locating centrohelids at the outgroup position to bikont organisms and locating between the branches of amoebozoa and opisthokonts were independently obtained by different data sets, but these locations were not clearly supported with statistical confidence.2. No clear support was obtained for the monophyly of chromalveolates including cryptophytes, haptophytes, stramenopiles, and alveolates.3. Phylogenies of elongation factors 1 α and 2 demonstrated that Dysnectes brevis and a flagellate resemble to D. brevis (NY0173) were located between the branchings of trichomonads and diplomonads, supporting the previous results based on the SSUrRNA phylogeny.