Baldauf S L, Doolittle W F
Canadian Institute for Advanced Research and Department of Biochemistry, Dalhousie University, Halifax, NS, Canada B3H 4H7.
Proc Natl Acad Sci U S A. 1997 Oct 28;94(22):12007-12. doi: 10.1073/pnas.94.22.12007.
The Mycetozoa include the cellular (dictyostelid), acellular (myxogastrid), and protostelid slime molds. However, available molecular data are in disagreement on both the monophyly and phylogenetic position of the group. Ribosomal RNA trees show the myxogastrid and dictyostelid slime molds as unrelated early branching lineages, but actin and beta-tubulin trees place them together as a single coherent (monophyletic) group, closely related to the animal-fungal clade. We have sequenced the elongation factor-1alpha genes from one member of each division of the Mycetozoa, including Dictyostelium discoideum, for which cDNA sequences were previously available. Phylogenetic analyses of these sequences strongly support a monophyletic Mycetozoa, with the myxogastrid and dictyostelid slime molds most closely related to each other. All phylogenetic methods used also place this coherent Mycetozoan assemblage as emerging among the multicellular eukaryotes, tentatively supported as more closely related to animals + fungi than are green plants. With our data there are now three proteins that consistently support a monophyletic Mycetozoa and at least four that place these taxa within the "crown" of the eukaryote tree. We suggest that ribosomal RNA data should be more closely examined with regard to these questions, and we emphasize the importance of developing multiple sequence data sets.
黏菌包括细胞性（盘基网柄菌目）、非细胞性（黏菌纲）和原柄菌目的黏菌。然而，现有的分子数据在该类群的单系性和系统发育位置上存在分歧。核糖体RNA树显示黏菌纲和盘基网柄菌目黏菌是不相关的早期分支谱系，但肌动蛋白和β-微管蛋白树将它们归为一个单一的连贯（单系）类群，与动物-真菌分支密切相关。我们对黏菌各分类单元的一个成员的延伸因子-1α基因进行了测序，其中包括此前已有cDNA序列的盘基网柄菌。对这些序列的系统发育分析有力地支持了黏菌是单系的，黏菌纲和盘基网柄菌目黏菌彼此关系最为密切。所使用的所有系统发育方法也将这个连贯的黏菌类群置于多细胞真核生物之中，初步证据表明它与动物+真菌的关系比与绿色植物更为密切。根据我们的数据，现在有三种蛋白质始终支持黏菌是单系的，至少有四种蛋白质将这些分类单元置于真核生物树的“冠部”内。我们建议应更仔细地研究核糖体RNA数据在这些问题上的情况，并且强调开发多个序列数据集的重要性。
