Hirt R P, Logsdon J M, Healy B, Dorey M W, Doolittle W F, Embley T M
Department of Zoology, The Natural History Museum, London SW7 5BD, United Kingdom.
Proc Natl Acad Sci U S A. 1999 Jan 19;96(2):580-5. doi: 10.1073/pnas.96.2.580.
We have determined complete gene sequences encoding the largest subunit of the RNA polymerase II (RBP1) from two Microsporidia, Vairimorpha necatrix and Nosema locustae. Phylogenetic analyses of these and other RPB1 sequences strongly support the notion that Microsporidia are not early-diverging eukaryotes but instead are specifically related to Fungi. Our reexamination of elongation factors EF-1alpha and EF-2 sequence data that had previously been taken as support for an early (Archezoan) divergence of these amitochondriate protists show such support to be weak and likely caused by artifacts in phylogenetic analyses. These EF data sets are, in fact, not inconsistent with a Microsporidia + Fungi relationship. In addition, we show that none of these proteins strongly support a deep divergence of Parabasalia and Metamonada, the other amitochondriate protist groups currently thought to compose early branches. Thus, the phylogenetic placement among eukaryotes for these protist taxa is in need of further critical examination.
我们已经确定了来自两种微孢子虫（毁灭棱形孢虫和蝗虫微孢子虫）的编码RNA聚合酶II最大亚基（RBP1）的完整基因序列。对这些以及其他RPB1序列的系统发育分析有力地支持了以下观点：微孢子虫并非早期分化的真核生物，而是与真菌有特定的亲缘关系。我们重新审视了先前被用作支持这些无线粒体原生生物早期（古原生动物）分化的延伸因子EF-1α和EF-2序列数据，结果表明这种支持很薄弱，可能是由系统发育分析中的人为因素导致的。实际上，这些EF数据集与微孢子虫+真菌的关系并不矛盾。此外，我们还表明，这些蛋白质均未有力地支持目前被认为构成早期分支的其他无线粒体原生生物类群——披发虫类和元滴虫类的深度分化。因此，这些原生生物类群在真核生物中的系统发育定位需要进一步的严格审查。
