Primitive cells of Asgard show life on the brink of complexity

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The finding that Lokis has actin tentacles adds plausibility to a so-called eukaryogenesis scenario. the inside out modelsaid Spang and Schleper. In 2014, cell biologist buzz baum at University College London and his cousin, the evolutionary biologist david baum from the University of Wisconsin, Madison, proposed an idea they had discussed at family events: that the first eukaryotes arose after a single ancestral cell extended protrusions beyond its cell walls. First these arms reached out to a symbiotic bacterium. They eventually closed around that partner, turning it into a proto-mitochondrion. Both the original archaeal cell and the captured symbiote were encased within a skeleton provided by arms.

Back when Asgard’s archaea were still known only from snippets of environmental DNA, Baum had asked attendees at a conference to draw pictures of what they thought the organisms would look like. His own drawing based on the inside-out ideas, which he predicted would sport protruding arms, shocked the other assembled scientists. At the time, Schleper said, it seemed “very strange that he would make this funny suggestion.”

A competitive environment

The events of eukaryogenesis have been so obscured by the intervention of time and gene sharing that we may never know for sure.

The two species of Loki currently in culture, for example, are modern organisms that differ from ancient archaea in the same way that a living singing cardinal differs from the ancestral dinosaur from which it evolved. The Loki group isn’t even the Asgardian subset of archaea that genetic analyzes suggest is most closely related to eukaryotes. (Based on known Asgard genomes, a preprint published by Ettema and colleagues in March argued that the ancestor of eukaryotes was a Heimdall’s archaeon).

Still, labs around the world are betting that cultivating more diverse representatives of the Asgard group will produce a bonanza of new clues about their common ancestry and ours. Schleper is trying. Emma too. Also Baum, who said that his lab will soon welcome a new colleague who will bring vials of archaea from groups like Heimdall and Odin. The same Imachi, who refused to talk to how many for this story

“If I were interviewed now, I would probably talk about new data that hasn’t been released yet,” he explained in an email, adding that his group applauded the efforts of Schleper’s team. “It’s very competitive now (although I don’t like this kind of competition),” he added.

Other sources also lamented the overly pressurized atmosphere. “It would be nice if the field was more open to sharing,” Spang said. The pressure is heaviest on young scientists who tend to take on high-risk, high-reward farming projects. Success can add a glow Nature paper to your resume. But wasting years on a failed endeavor can stunt your chances of landing a science job. “It’s really an unfair situation,” Schleper said.

For now, however, the race is on. When the Baum cousins ​​published their ideas on eukaryogenesis in 2014, Buzz Baum said, they assumed we’d probably never know the truth. Then suddenly the Asgard appeared, offering new glimpses of the liminal stages of transition that propelled life from single-celled simplicity to overdrive.

“Before we destroy this beautiful planet, we should do some research, because there are cool things on planet Earth that we don’t know anything about. Maybe there are things that are kind of living fossils, intermediate states,” he said. “Maybe it’s on my shower curtain.”

original story reprinted with permission from how much magazine, an editorially independent publication of the simons foundation whose mission is to enhance public understanding of science by covering research developments and trends in mathematics and the physical and life sciences.