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Archaeal genomics is a scientific discipline that concerns the genome, encompassing the entire hereditary information, of Archaea, a domain of organisms consisting of single, nucleus-free cells, distinct from bacteria and eukaryotes.
The Archaea was recognized as a third domain of life 40 years ago. In this Review, Eme et al. outline a brief history of the changing shape of the tree of life and examine how the recent discovery of diverse archaeal lineages has changed our understanding of the evolutionary relationships between the three domains of life and the origin of the eukaryotic cell.
Methanonatronarchaeia are a distinct class-level lineage of extremely halophilic methanogens, which lack features of classical methanogenesis and have a high intracellular concentration of potassium, suggesting potassium-based osmoprotection.