Insights into the evolutionary origin and genome architecture of the unicellular opisthokonts Capsaspora owczarzaki and Sphaeroforma arctica
Insights into the evolutionary origin and genome architecture of the unicellular opisthokonts Capsaspora owczarzaki and Sphaeroforma arctica
复制标题
DOI：
10.1111/j.1550-7408.2006.00118.x
复制
发表时间：
2006-09-01
影响因子：
2.2
通讯作者：
Roger, Andrew J.
中科院分区：
文献类型：
--
作者：
Ruiz-Trillo, Inaki;Lane, Christopher E.;Roger, Andrew J.
最近的分子系统发育分析表明，单细胞变形虫原生生物Capsaspora owczarzaki不太可能像之前描述的那样是核虫或鱼孢子虫，而是与后生动物、Choanoflagellata和鱼孢子虫有更密切的关系。然而，Capsaspora与其他原生opisthokont谱系的具体系统发育关系尚不清楚。为了验证这些早期的结果，我们扩大了分类样本和单细胞谱系的基因数量。对C. owczarzaki和鱼孢子动物Sphaeroforma arctica的蛋白编码基因伸长因子1- α (ef1 - α)和热休克蛋白70 （Hsp70）进行了测序。我们对ef1 - α、Hsp70和actin蛋白序列的最大似然（ML）和贝叶斯分析表明，C. owczarzaki与任何单细胞opisthokonts都没有明确的亲缘关系，但代表了与动物和鞭毛动物密切相关的独立单细胞谱系。此外，我们还发现S. arctic鱼孢子虫具有EF-like （EFL）基因拷贝，而不是典型的EF1-alpha基因拷贝，这是迄今为止在鱼孢子虫中首次描述的EF1-alpha基因拷贝。最大似然系统发育分析表明，北极S. efa -like基因与鞭藻类efa -like基因具有较强的类群。最后，为了开始表征Capsaspora基因组，我们进行了脉冲场凝胶电泳（PFGE）分析，结果表明其基因组至少有12条染色体，总基因组大小在22-25 Mb之间。
Molecular phylogenetic analyses have recently shown that the unicellular amoeboid protist Capsaspora owczarzaki is unlikely to be a nucleariid or an ichthyosporean as previously described, but is more closely related to Metazoa, Choanoflagellata, and Ichthyosporea. However, the specific phylogenetic relationship of Capsaspora to other protist opisthokont lineages was poorly resolved. To test these earlier results we have expanded both the taxonomic sampling and the number of genes from opisthokont unicellular lineages. We have sequenced the protein-coding genes elongation factor 1-alpha (EF1-alpha) and heat shock protein 70 (Hsp70) from C. owczarzaki and the ichthyosporean Sphaeroforma arctica. Our maximum likelihood (ML) and Bayesian analyses of a concatenated alignment of EF1-alpha, Hsp70, and actin protein sequences with a better sampling of opisthokont-related protist lineages indicate that C. owczarzaki is not clearly allied with any of the unicellular opisthokonts, but represents an independent unicellular lineage closely related to animals and choanoflagellates. Moreover, we have found that the ichthyosporean S. arctica possesses an EF-like (EFL) gene copy instead of the canonical EF1-alpha, the first so far described in an ichthyosporean. A maximum likelihood phylogenetic analysis shows that the EF-like gene of S. arctica strongly groups with the EF-like genes from choanoflagellates. Finally, to begin characterizing the Capsaspora genome, we have performed pulsed-field gel electrophoresis (PFGE) analyses, which indicate that its genome has at least 12 chromosomes with a total genome size in the range of 22-25 Mb.