Phylogenetic analysis of beta-tubulin sequences from amitochondrial protozoa.
Phylogenetic analysis of beta-tubulin sequences from amitochondrial protozoa.
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线粒体原生动物β-微管蛋白序列的系统发育分析。
DOI：
10.1006/mpev.1996.0031
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发表时间：
1996
期刊：
影响因子：
--
通讯作者：
Katiyar,SK
中科院分区：
文献类型：
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作者：
Edlind,TD;Li,J;Visvesvara,GS;Vodkin,MH;McLaughlin,GL;Katiyar,SK
有人提出，某些现存的厌氧原生动物是在获得线粒体之前在真核生物进化早期分化的生物的后代。其中包括胞外寄生虫，蓝氏贾第鞭毛虫，阴道毛滴虫，溶组织内阿米巴，以及专性胞内微孢子虫。对这些非线粒体生物rRNA序列的系统发育分析表明，G。蓝氏菌、阴道毛滴虫和微孢子虫位于真核生物树的底部附近，而微孢子虫则位于树的底部。组织溶解与含有线粒体的物种聚集在一起。然而，由于真核生物可能是通过共生关系进化而来的，因此分析其他可能具有独立起源的序列是很重要的。与核糖体不同，微管似乎是真核生物所特有的。微管β-微管蛋白亚基的完整基因序列。阴道蠕形虫、溶组织棘球绦虫和微孢子虫脑孢子虫是最近新发现的。利用距离矩阵和简约方法，利用β-微管蛋白外群和α-微管蛋白外群，分析了兰氏革兰氏菌和另外20个γ-微管蛋白之间的系统发育关系。所有的分析都把你。位于β-微管蛋白进化树底部的组织溶解序列。前人也得到了类似的结果。组织溶解α-微管蛋白使用一组较不具代表性的序列。相比之下，你。在含有动物和真菌β微管蛋白的谱系中，HellemSequence的分枝程度相当高。对于β-微管蛋白和rRNA树之间的这些意外差异，考虑了可能的解释。
It has been proposed that certain extant anaerobic protozoa are descended from organisms that diverged early in eukaryotic evolution prior to the acquisition of mitochondria. Among these are the extracellular parasitesGiardia lamblia, Trichomonas vaginalis,andEntamoeba histolytica,and the obligately intracellular microsporidia. Phylogenetic analysis of rRNA sequences from these amitochondrial organisms suggests thatG. lamblia, T. vaginalis,and microsporidia are near the base of the eukaryotic tree, whileE. histolyticaclusters with mitochondria-containing species. However, since eukaryotes likely evolved by symbiotic associations, it is important to analyze other sequences which may have independent origins. Unlike ribosomes, microtubules appear to be unique to eukaryotes. Complete gene sequences for the β-tubulin subunit of microtubules fromT. vaginalis, E. histolytica,and the microsporidianEncephalitozoon hellemhave recently been determined. Phylogenetic relationships among these,G. lamblia,and 20 additional β-tubulins were analyzed by distance matrix and parsimony methods, using α- and γ-tubulin outgroups. All analyses placed theE. histolyticasequence at the base of the β-tubulin evolutionary tree. Similar results were obtained forE. histolyticaα-tubulin using a less representative set of sequences. In contrast, theE. hellemsequence branched considerably higher, within the lineage containing animal and fungal β-tubulins. Possible explanations are considered for these unexpected differences between the β-tubulin and rRNA trees.