The deep marine environment has proved to be a rich source of novel microbes. More recently a newly identified group of deep sea-dwelling archaea (prokaryotic, primitive microorganisms) have been revealed to possess a number of genes found in eukaryotes. These genes control intracellular membrane processing, typically during processes like phagocytosis.
The hypothesis is that these prokaryotes, named Lokiarchaea, are remnants of the evolutionary transition towards more complex cellular forms.
The Lokiarchaea housekeeping genes are archaeal but phylogenetic analysis of the Lokiarchaea genome positions the organisms with eukaryotes on the tree of life. The conclusion? Lokiarchaea share a common ancestor.
The function of the eukaryote-like genes is also intriguing. The researchers conducting the study suggest that Lokiarchaea was at a stage where it started evolving a primitive way of taking up material via phagocytosis.
Lokiarchaea is a modern-day organism with a history of the steps that occurred during eukaryote origin. Another possibility is the appearance of a mechanism to take up alpha-proteobacteria from which mitochondria evolved.
One expert commentator remarked: “In the field of the origin of eukaryotic cells, this is probably one of the biggest new discoveries that we’ve seen for 30 years or so. It’s a true so-called missing link between archaea and eukaryotes.”