Living Systems Institute, University of Exeter, Exeter, UK.
Wissenschaftskolleg zu Berlin, Berlin, Germany.
Nat Microbiol. 2020 Jan;5(1):154-165. doi: 10.1038/s41564-019-0605-4. Epub 2019 Nov 25.
Most eukaryotic microbial diversity is uncultivated, under-studied and lacks nuclear genome data. Mitochondrial genome sampling is more comprehensive, but many phylogenetically important groups remain unsampled. Here, using a single-cell sorting approach combining tubulin-specific labelling with photopigment exclusion, we sorted flagellated heterotrophic unicellular eukaryotes from Pacific Ocean samples. We recovered 206 single amplified genomes, predominantly from underrepresented branches on the tree of life. Seventy single amplified genomes contained unique mitochondrial contigs, including 21 complete or near-complete mitochondrial genomes from formerly under-sampled phylogenetic branches, including telonemids, katablepharids, cercozoans and marine stramenopiles, effectively doubling the number of available samples of heterotrophic flagellate mitochondrial genomes. Collectively, these data identify a dynamic history of mitochondrial genome evolution including intron gain and loss, extensive patterns of genetic code variation and complex patterns of gene loss. Surprisingly, we found that stramenopile mitochondrial content is highly plastic, resembling patterns of variation previously observed only in plants.
大多数真核微生物多样性尚未被培养、研究，且缺乏核基因组数据。线粒体基因组采样更为全面，但仍有许多在系统发育上重要的群体未被采样。在这里，我们使用一种单细胞分选方法，结合微管蛋白特异性标记和光色素排除，从太平洋样本中分选鞭毛异养单细胞真核生物。我们回收了 206 个单扩增基因组，主要来自生命之树中代表性不足的分支。70 个单扩增基因组包含独特的线粒体连续序列，包括 21 个完整或接近完整的线粒体基因组，来自以前采样不足的系统发育分支，包括端毛目、铠纤动物、原生动物和海洋不等鞭毛类，有效地将异养鞭毛线粒体基因组的可用样本数量增加了一倍。总的来说，这些数据揭示了线粒体基因组进化的动态历史，包括内含子的获得和丢失、广泛的遗传密码变异模式以及复杂的基因丢失模式。令人惊讶的是，我们发现不等鞭毛类线粒体的内容具有高度的可塑性，类似于以前仅在植物中观察到的变异模式。
