nucleation

THEORY-1200: The Asgard archaeal ancestor of eukaryotes depended on metabolic partners: like Candidatus Prometheoarchaeum syntrophicum, it degraded amino acids in syntrophy, handing hydrogen and formate to partners that removed them

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Properties5
StatusProposed
Tagsendosymbiosis, natural-sciences
SourceLIT-1591 — Isolation of an archaeon at the prokaryote–eukaryote interface
ExtendsTHEORY-1108 — On Imachi and colleagues' cultivation of Candidatus Prometheoarchaeum syntrophicum MK-D1, the first Asgard archaeon grown in the laboratory is a small, internally simple coccus with long branching protrusions that degrades amino acids only in syntrophy, handing hydrogen and formate to partners that can be exchanged, and from its genome and other Asgard genomes the authors infer that the Asgard ancestor was likewise dependent on metabolic partners; the isolate is a modern relative separated from the host lineage by about two billion years, grown only in co-culture, and the entangle–engulf–endogenize model built on it is a hypothesis the authors call not definitive
Bears onQUESTION-277 — When formerly autonomous partners come to depend on one another, which of mutual dependence, reproductive cohesion, the distribution of essential functions across genomes, the host's regulatory control and the alignment of selection does each route to dependence bring about, and which of them, alone or together, make the partnership a new evolutionary individual?

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Source

Imachi et al. (2020), LIT-1591, read in full in NOTE-1238. The authors infer an ancestor that “depended on metabolic partners, although we do not reject the possibility of other additional lifestyles”.

Where the evidence stands

What the paper shows, and what it does not, is THEORY-1108, Active, which this entry extends: that entry is the reading, this one the thesis. The promote_when above is THEORY-1108’s condition before the twenty-second status review promoted it, carried here unchanged, because it asks what would make the thesis true and not what the paper says.

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