Asgard Archaea Crawl Using Dynamic Protrusions

Researchers have observed actin-dependent crawling motility and dynamic protrusions in Asgard archaea, a group of microorganisms that are considered close relatives of eukaryotes. This discovery, detailed in a study published online on September 30, 2026, in the journal Nature, was made possible through anoxic live-cell imaging techniques. The findings provide significant insights into the cellular innovations that may have played a role in the evolutionary transition from prokaryotic to eukaryotic life.

Asgard archaea are a phylum of archaea that have gained considerable attention in recent years due to their phylogenetic proximity to eukaryotes. Their genomes contain genes that were previously thought to be exclusive to eukaryotes, suggesting a shared ancestry and a more complex evolutionary history than initially understood. The ability to crawl, mediated by dynamic protrusions, represents a sophisticated form of motility that has been observed in various eukaryotic cells, including amoebas and immune cells. The identification of this capability in Asgard archaea suggests that such mechanisms may have originated in the archaeal lineage before the emergence of eukaryotes.

The study utilized anoxic conditions to maintain the viability of the Asgard archaea during observation, as these organisms are typically found in oxygen-depleted environments. Live-cell imaging allowed scientists to visualize the dynamic processes occurring within the cells in real-time. The researchers identified specific actin-based structures that are extended and retracted, enabling the cells to move across surfaces. Actin is a protein that forms filaments and is a key component of the cytoskeleton in eukaryotic cells, involved in cell shape, movement, and division. Its presence and function in mediating motility in Asgard archaea further strengthen the link between these archaea and the eukaryotic lineage.

The implications of this research extend to our understanding of the origins of complex life. The evolution of eukaryotes, characterized by their complex cellular structures and functions, is a pivotal event in the history of life on Earth. Understanding the cellular capabilities of organisms like Asgard archaea, which represent the closest known prokaryotic relatives to eukaryotes, is crucial for reconstructing the ancestral features of the eukaryotic cell. The observed crawling motility and dynamic protrusions could be ancestral traits that were inherited and further elaborated upon by early eukaryotic ancestors. This research contributes to a growing body of evidence that points to an archaeal origin for many fundamental eukaryotic innovations, including complex cytoskeletal systems and sophisticated motility mechanisms. The study's publication in Nature, a leading scientific journal, underscores the significance of these findings for the fields of evolutionary biology, microbiology, and cell biology.