Hydrothermal vent near where Loki was found in marine sediments UNIVERSITY OF BERGEN CENTRE FOR GEOBIOLOGY, R.B. PEDERSENA newly identified group of deep sea-dwelling microbes has been classified as archaea—prokaryotic, primitive microorganisms. But these microbes harbor a suite of genes found in eukaryotes which are typically used to remodel intracellular membranes to form vesicles, or for phagocytosis. This “genomic starter kit” could have enabled ancestral forms of these microbes, named Lokiarchaea, to evolve into more complex eukaryotic cells, according to results published today (May 6) in Nature. The discovery supports the long-standing hypothesis that archaea are the ancestors of eukaryotes, and helps fill an evolutionary gap between the two groups.
“This is the most exciting and important paper on big questions about eukaryotic origins and the tree of life in years,” said evolutionary biologist Jeffrey Palmer of Indiana University, Bloomington, who was not involved with the work. “This should have a major effect on textbook treatment of these subjects.”
Since the late 1980s, all life forms have been split into three groups on the phylogenetic tree of life: bacteria, archaea, and eukaryotes. Eukaryotes and archaea have long been considered “sister groups” based on similarities in their genes and metabolic pathways. But it wasn’t clear whether eukaryotes and archaea shared a common ancestor, or if eukaryotes originated within a subset of archaea.
Thijs Ettema of Uppsala University in Sweden and his colleagues identified the new group ...
