Scientists glimpse oddball microbe that could help explain rise of complex life
(Nature) Biologists have for the first time captured and grown an elusive type of microbe that is similar to those that might have given rise to all complex life on Earth.
In a preprint posted to the bioRxiv repository, scientists in Japan report that they have isolated and grown microbes from an ancient lineage of archaea — single-celled microbes that look, superficially, like bacteria but are quite distinct — that was previously known only from genomic sequences.
…One genome stood out. It was clearly a member of the archaea. But dotted throughout this genome were eukaryotic-like genes, suggesting to Ettema that this oddball could help to bridge the evolutionary gap between simpler microbes and eukaryotes. The researchers called it Lokiarchaea, after Loki, the trickster of Norse mythology.
Soon, other labs found additional Loki-like archaea, and together these formed the Asgard archaea, named after a mythological region inhabited by Norse gods. Although the organisms’ precise place in the tree of life remains contentious, many analyses pair Asgards and eukaryotes together, which could mean that some distant Asgard-like ancestor gave rise to all eukaryotes — everything from panda bears to portabello mushrooms.
…“We can’t just go back in time and observe what happened,” says Ettema. The Asgards we see today are not the same as the microbe that gave rise to eukaryotes. But he says that culturing more Asgards and studying what their eukaryotic-like genes actually do will give a fuller picture of the evolutionary tree, and help researchers to better infer how simple, single-celled organisms made the first giant leap towards complexity
Archaea are often found in extreme environments, such as these chimneys on the summit of Giggenbach underwater volcano, off New Zealand.
Credit: New Zealand-American Submarine Ring of Fire 2005 Exploration, NOAA Vents Program