Multiple Independent Changes in Mitochondrial Genome Conformation in Chlamydomonadalean Algae.
Multiple Independent Changes in Mitochondrial Genome Conformation in Chlamydomonadalean Algae.
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DOI：
10.1093/gbe/evx060
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发表时间：
2017-04-01
影响因子：
3.3
通讯作者：
Smith DR
中科院分区：
文献类型：
--
作者：
Hamaji T;Kawai-Toyooka H;Toyoda A;Minakuchi Y;Suzuki M;Fujiyama A;Nozaki H;Smith DR
衣藻绿藻对线性线粒体基因组并不陌生，尤其是莱因哈丁藻分支的成员。已知至少九种不同的莱茵衣藻物种具有线性线粒体 DNA (mtDNA)，其中包括模式物种莱茵衣藻。因此，一些人认为莱因哈丁虫分支的最近共同祖先具有线性线粒体DNA也就不足为奇了。但最近在一系列Reinhardtinia藻类（例如Volvox carteri和Tetrabaena Socialis）中发现的环状线粒体DNA让人们对这一假设产生了怀疑。在这里，我们探索了 Reinhardtinia 藻类 Yamagishiella unicocca 和 Eudorina sp 中的 mtDNA 序列和结构。 NIES-3984，在具有相反 mtDNA 作图结构的物种之间占据系统发育中间位置。测序和凝胶电泳数据表明，Y. unicocca 具有线性单体线粒体基因组和长（3 kb）回文端粒。相反，Eudorina sp. 的 mtDNA 尽管与 Y. unicocca 具有相同的基因顺序，但仍组装为圆形作图分子。 Eudorina sp. 的限制性消化。 mtDNA 支持其圆形图谱，但也揭示了线性单体形式，其结构和基因顺序与 Y. unicocca mtDNA 相匹配。基于这些数据，我们认为Reinhardtinia中的mtDNA构象至少存在三个独立的转变，并且该分支的共同祖先具有带有回文端粒的线性单体线粒体基因组。
Chlamydomonadalean green algae are no stranger to linear mitochondrial genomes, particularly members of the Reinhardtinia clade. At least nine different Reinhardtinia species are known to have linear mitochondrial DNAs (mtDNAs), including the model species Chlamydomonas reinhardtii. Thus, it is no surprise that some have suggested that the most recent common ancestor of the Reinhardtinia clade had a linear mtDNA. But the recent uncovering of circular-mapping mtDNAs in a range of Reinhardtinia algae, such as Volvox carteri and Tetrabaena socialis, has shed doubt on this hypothesis. Here, we explore mtDNA sequence and structure within the colonial Reinhardtinia algae Yamagishiella unicocca and Eudorina sp. NIES-3984, which occupy phylogenetically intermediate positions between species with opposing mtDNA mapping structures. Sequencing and gel electrophoresis data indicate that Y. unicocca has a linear monomeric mitochondrial genome with long (3 kb) palindromic telomeres. Conversely, the mtDNA of Eudorina sp., despite having an identical gene order to that of Y. unicocca, assembled as a circular-mapping molecule. Restriction digests of Eudorina sp. mtDNA supported its circular map, but also revealed a linear monomeric form with a matching architecture and gene order to the Y. unicocca mtDNA. Based on these data, we suggest that there have been at least three separate shifts in mtDNA conformation in the Reinhardtinia, and that the common ancestor of this clade had a linear monomeric mitochondrial genome with palindromic telomeres.