Excitement is gathering around research published in Nature in which scientists say they have discovered a novel candidate archaeal phylum, or the potential missing link between archaea and eukaryotes.
In the paper, the Uppsala University-led team performed deep metagenomic sequencing on a group of microorganisms they dubbed Lokiarchaeota and assembled a 92 percent complete, 5.1 megabase pair composite sequence of the microbes.
They determined that 175 proteins were more similar to proteins found in eukaryotes than proteins found in bacterial or archaeal proteins, and a phylogenetic analysis further suggested that Lokiarchaeota and eukaryotes share a common ancestor, the researchers write.
"Our results provide strong support for hypotheses in which the eukaryotic host evolved from a bona fide archaeon, and demonstrate that many components that underpin eukaryote-specific features were already present in that ancestor," the researchers write. "This provided the host with a rich genomic 'starter-kit' to support the increase in the cellular and genomic complexity that is characteristic of eukaryotes."
While the function of the eukaryote-like genes remains unknown and the researchers plan to culture the microbes and visualize them in the lab, reaction to the finding has bordered on the euphoric.
"This is a great paper," Martin Embley at Newcastle University told NPR Shots. "It's a real, real breakthrough."
Meanwhile, Eugene Koonin at the Nationa lCenter for Biotechnology Information tells The Washington Post that the findings "clinch the case for the origin of eurkaryotes from within the archaeal diversity and point to a specific part of the archaeal evolutionary tree where eukaryotes belong."
Andrew Roger an evolutionary biologist at Dalhousie University told The Scientist that it is highly probable that the genes in Lokiarchaeota are functional. "We can't say for sure, but genes don’t hang around in organisms for a long time without being mutated into junk unless they're expressed … I'd be surprised if these organisms don't have some kind of endomembrane and cytoskeletal system.
"In the field of the origin of eurkaryotic cells, this is probably one of the biggest new discoveries that we've seen for 30 years or so," he says. "It's a true so-called missing link between archaea and eukaryotes."