The origin of the eukaryotic cell is one of the greatest mysteries in modern biology. Eukaryotic-wide specific biological processes arose in the lost ancestors of eukaryotes. These distinctive features, such as the actin cytoskeleton, define what it is to be a eukaryote. Recent sequencing, characterization, and isolation of Asgard archaea have opened an intriguing window into the pre-eukaryotic cell. Firstly, sequencing of anaerobic sediments identified a group of uncultured organisms, Asgard archaea, which contain genes with homology to eukaryotic signature genes. Secondly, characterization of the products of these genes at the protein level demonstrated that Asgard archaea have related biological processes to eukaryotes. Finally, the isolation of an Asgard archaeon has produced a model organism in which the morphological consequences of the eukaryotic-like processes can be studied. Here, we consider the consequences for the Asgard actin cytoskeleton and for the evolution of a regulated actin system in the archaea-to-eukaryotic transition.

真核细胞的起源是现代生物学中最大的谜团之一。真核生物的特定祖先过程是由真核生物引起的。这些独特的特征，例如肌动蛋白细胞骨架，定义了什么是真核生物。最近对Asgard古细菌的测序，鉴定和分离为真核细胞打开了一个有趣的窗口。首先，对厌氧沉积物进行测序，确定了一组未经培养的生物，即阿斯加德古细菌，它们含有与真核签名基因具有同源性的基因。其次，在蛋白质水平上对这些基因产物的表征表明，古细菌Asgard与真核生物具有相关的生物学过程。最后，阿斯加德古人的分离产生了一个模型生物，在其中可以研究真核生物样过程的形态学后果。在这里，我们考虑了古细菌到真核生物过渡中Asgard肌动蛋白细胞骨架和受调节的肌动蛋白系统进化的后果。