Apr 12, 2023 05:51 PM
https://www.quantamagazine.org/primitive...-20230411/
EXCERPTS: . . . But this was no complex cell. It looked more ancestral, primordial. The organism, first published in Nature, is only the second representative of a group of microbes called Asgard archaea to be grown and studied in detail. Coaxing it to grow out of a tiny spoonful of seafloor sludge, which took six years, was like preparing a dressing room for a temperamental celebrity. The organism couldn’t be centrifuged, stirred, exposed to oxygen, separated from a few other microbes it pals around with, or rushed into growing any faster than a glacial pace.
For months, it didn’t even grow at all. “I worried also for my own future in science,” said Thiago Rodrigues-Oliveira, who led the effort to cultivate the new species as a postdoc in Schleper’s lab, betting his own career on the whims of a single, recalcitrant organism.
As excruciatingly difficult as they are to deal with, the Asgard archaea are now among the most coveted organisms in science, and for good reason. To many evolutionary biologists, their discovery and subsequent studies justify revising the textbook pictures of the tree of life to situate us — and every other creature built from eukaryotic cells — as mere offshoots of the Asgard group.
[...] Within the now-dominant two-domain picture to which the Asgard archaea are contributing, the big story of life on this planet goes something like this. Some 4 billion years ago, life forked into two single-celled branches, the archaea and the bacteria.
Genetic evidence implies that the two branches crossed again 2 billion years later when an archaeon — likely from the Asgard group — somehow ingested a bacterium. The process domesticated what was once a distinct, free-living cell and turned it into the organelles called mitochondria that persist inside eukaryotic cells. The descendants of that fateful union branched into other single-celled organisms like dinoflagellates, and then later into multicellular creatures that grew to macroscopic sizes, left fossils behind, and colonized both sea and land.
But even theorists who stand behind this narrative belong to divided camps. Some argue that gaining mitochondria was the defining event in eukaryogenesis. Others insist that mitochondria arrived late in an ongoing transition... (MORE - missing details)
EXCERPTS: . . . But this was no complex cell. It looked more ancestral, primordial. The organism, first published in Nature, is only the second representative of a group of microbes called Asgard archaea to be grown and studied in detail. Coaxing it to grow out of a tiny spoonful of seafloor sludge, which took six years, was like preparing a dressing room for a temperamental celebrity. The organism couldn’t be centrifuged, stirred, exposed to oxygen, separated from a few other microbes it pals around with, or rushed into growing any faster than a glacial pace.
For months, it didn’t even grow at all. “I worried also for my own future in science,” said Thiago Rodrigues-Oliveira, who led the effort to cultivate the new species as a postdoc in Schleper’s lab, betting his own career on the whims of a single, recalcitrant organism.
As excruciatingly difficult as they are to deal with, the Asgard archaea are now among the most coveted organisms in science, and for good reason. To many evolutionary biologists, their discovery and subsequent studies justify revising the textbook pictures of the tree of life to situate us — and every other creature built from eukaryotic cells — as mere offshoots of the Asgard group.
[...] Within the now-dominant two-domain picture to which the Asgard archaea are contributing, the big story of life on this planet goes something like this. Some 4 billion years ago, life forked into two single-celled branches, the archaea and the bacteria.
Genetic evidence implies that the two branches crossed again 2 billion years later when an archaeon — likely from the Asgard group — somehow ingested a bacterium. The process domesticated what was once a distinct, free-living cell and turned it into the organelles called mitochondria that persist inside eukaryotic cells. The descendants of that fateful union branched into other single-celled organisms like dinoflagellates, and then later into multicellular creatures that grew to macroscopic sizes, left fossils behind, and colonized both sea and land.
But even theorists who stand behind this narrative belong to divided camps. Some argue that gaining mitochondria was the defining event in eukaryogenesis. Others insist that mitochondria arrived late in an ongoing transition... (MORE - missing details)