小柯机器人

瑞典乌普萨拉大学Thijs J. G. Ettema研究组揭示真核生物的海姆达拉海族祖先的推断和重建。该研究于2023年6月14日在线发表于国际一流学术期刊《自然》。

研究人员分析了阿斯加德古菌的扩大基因组抽样的不同系统发育标记数据集，并使用最先进的系统发育方法评估相互竞争的演化方案。研究人员发现，真核生物在阿斯加德古菌中作为一个良好的嵌套支系，并作为Hodarchaeales的姐妹系，这是海姆达尔古菌中新提出的一个目。利用复杂的基因树和物种树调和方法，研究人员表明，与真核生物基因组的演化类似，与其他古细菌相比，阿斯加德古细菌的基因组演化涉及明显的基因复制和较少的基因丢失事件。

最后，研究人员推断，阿斯加德古菌的最后一个共同祖先可能是一个嗜热的化能无机自养生物，而真核生物所演化出的谱系则适应了中温条件，并获得了支持异养生活方式的遗传潜力。这项工作为原核生物向真核生物的过渡提供了关键的见解，并为更好地理解真核细胞中细胞复杂性的出现提供了一个平台。

据介绍，在目前关于真核发生的争论中，即导致真核细胞从原核祖先中出现的一系列演化事件，阿斯加德古菌的成员作为真核生物最接近的古菌亲属发挥了关键作用。然而，阿斯加德古菌和真核生物的最后一个共同祖先的性质和系统发育特征仍未解决。

附：英文原文

Title: Inference and reconstruction of the heimdallarchaeial ancestry of eukaryotes

Author: Eme, Laura, Tamarit, Daniel, Caceres, Eva F., Stairs, Courtney W., De Anda, Valerie, Schn, Max E., Seitz, Kiley W., Dombrowski, Nina, Lewis, William H., Homa, Felix, Saw, Jimmy H., Lombard, Jonathan, Nunoura, Takuro, Li, Wen-Jun, Hua, Zheng-Shuang, Chen, Lin-Xing, Banfield, Jillian F., John, Emily St, Reysenbach, Anna-Louise, Stott, Matthew B., Schramm, Andreas, Kjeldsen, Kasper U., Teske, Andreas P., Baker, Brett J., Ettema, Thijs J. G.

Issue&Volume: 2023-06-14

Abstract: In the ongoing debates about eukaryogenesis—the series of evolutionary events leading to the emergence of the eukaryotic cell from prokaryotic ancestors—members of the Asgard archaea play a key part as the closest archaeal relatives of eukaryotes1. However, the nature and phylogenetic identity of the last common ancestor of Asgard archaea and eukaryotes remain unresolved2–4. Here we analyse distinct phylogenetic marker datasets of an expanded genomic sampling of Asgard archaea and evaluate competing evolutionary scenarios using state-of-the-art phylogenomic approaches. We find that eukaryotes are placed, with high confidence, as a well-nested clade within Asgard archaea and as a sister lineage to Hodarchaeales, a newly proposed order within Heimdallarchaeia. Using sophisticated gene tree and species tree reconciliation approaches, we show that analogous to the evolution of eukaryotic genomes, genome evolution in Asgard archaea involved significantly more gene duplication and fewer gene loss events compared with other archaea. Finally, we infer that the last common ancestor of Asgard archaea was probably a thermophilic chemolithotroph and that the lineage from which eukaryotes evolved adapted to mesophilic conditions and acquired the genetic potential to support a heterotrophic lifestyle. Our work provides key insights into the prokaryote-to-eukaryote transition and a platform for better understanding the emergence of cellular complexity in eukaryotic cells. Analyses of multiple phylogenetic marker datasets of Asgard archaea provide insight into the transition from prokaryotes to eukaryotes, specifically placing eukaryotes within Asgard archaea and as a sister lineage to Hodarchaeales.

DOI: 10.1038/s41586-023-06186-2

Source: https://www.nature.com/articles/s41586-023-06186-2

Nature：《自然》，创刊于1869年。隶属于施普林格·自然出版集团，最新IF：69.504
官方网址：http://www.nature.com/
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