Siddall M E, Stokes N A, Burreson E M
School of Marine Science, Virginia Institute of Marine Science, College of William and Mary, Gloucester Point 23062, USA.
Mol Biol Evol. 1995 Jul;12(4):573-81. doi: 10.1093/oxfordjournals.molbev.a040237.
The phylogenetic position of the phylum Haplosporidia among other protists was investigated with the complete 16S-like rRNA gene sequences from two species in the phylum: Haplosporidium nelsoni, a parasite of oysters, and Minchinia teredinis, a parasite of shipworms. Because the lack of obvious morphological homologies with other protists hampered decisions regarding taxonomic composition for sequence alignment and phylogenetic analysis, the complete sequences for these two haplosporidians were directed as search queries to the blast/ncbi.nlm.nih.gov electronic mail server. The results of this heuristic similarity search provided a basis for constructing a preliminary higher-taxonomic-level analysis comparing the haplosporidians with species from the slime molds, fungi, algae, amoebae, ciliates, dinoflagellates, and apicomplexans. Maximum parsimony yielded equivocal results, whereas transversionally weighted parsimony suggested an affinity with the alveolates (i.e., the ciliates, dinoflagellates, and apicomplexans). Multiple alignment of the two haplosporidian sequences against 17 taxa in a secondary analysis focusing on the alveolates and subsequent parsimony analysis placed the phylum Haplosporidia as a monophyletic group within the Alveolata and as a taxon of equal rank with the other three alveolate phyla. The precise placement within the Alveolata was sensitive to weighting.
利用单孢子虫门中两个物种的完整16S样rRNA基因序列，研究了单孢子虫门在其他原生生物中的系统发育位置。这两个物种分别是：寄生于牡蛎的尼尔森单孢子虫（Haplosporidium nelsoni）和寄生于船蛆的船蛆米钦虫（Minchinia teredinis）。由于缺乏与其他原生生物明显的形态同源性，阻碍了对用于序列比对和系统发育分析的分类组成的判断，因此将这两种单孢子虫的完整序列作为搜索查询，发送至blast/ncbi.nlm.nih.gov电子邮件服务器。这种启发式相似性搜索的结果为构建一个初步的高级分类水平分析提供了基础，该分析将单孢子虫与黏菌、真菌、藻类、变形虫、纤毛虫、甲藻和顶复门的物种进行了比较。最大简约法得出了模棱两可的结果，而颠换加权简约法表明其与囊泡虫类（即纤毛虫、甲藻和顶复门）有亲缘关系。在针对囊泡虫类的二次分析中，将这两种单孢子虫的序列与17个分类单元进行多重比对，随后进行简约分析，结果表明单孢子虫门在囊泡虫类中是一个单系类群，与其他三个囊泡虫门处于同等分类等级。在囊泡虫类中的精确位置对加权很敏感。
