Man's Microbe Evolutionary Ancestor 'Loki' Calls Atlantic Volcanos Home

Researchers in Sweden claim to have found the missing link between complex life cells and the simple bacteria.

The organism named Lokiarchaeota or Loki, found in depths of the North Atlantic, is an archaea, a simple like bacteria microbe but possesses traits of complex eukaryotic cells. This group of organisms discovered in the 1970s was placed on the tree of life as an evolutionary intermediary between simple bacteria and complex cells.

Researchers who studied Loki DNA found that it had genes that eukaryotic cells have, including genes that encode skeleton-building proteins. That Loki was more complex than other archaea that have been studied, was clear. Loki was found close to a volcanic vent along the Mid-Atlantic Ridge.

"By studying its genome, we found that Loki represents an intermediate form in-between the simple cells of microbes, and the complex cell types of eukaryotes," said Thijs Ettema of Uppsala University the study's lead. Researchers also found that Loki can gobble up other microbes or molecules.

Theories of evolution from simple cells to complex life abound but the finding of Loki is helping consolidate some. For one, researchers have now learnt that complexity in cellular structure arose early on during the transition.

One of the biggest mysteries that researches seek to answer is the emergence of mitochondria which comprises loosely held DNA unlike the tightly packed nuclear genome. Current study suggests that early-eukaryotic ancestors like Loki gobbled up free-living bacteria which fuelled complexity and became mitochondrial DNA.

Researchers hope further studies on Loki DNA can provide more insight.

"The puzzle of the origin of the eukaryotic cell is extremely complicated, as many pieces are still missing. We hoped that Loki would reveal a few more pieces of the puzzle, but when we obtained the first results, we couldn't believe our eyes. The data simply looked spectacular," Ettema said.