nucleation

LIT-1566: Dated gene duplications elucidate the evolutionary assembly of eukaryotes

2 min read

Properties5
StatusActive — read in full 2026-10-27 (NOTE-1234) from the PubMed Central copy of the version of record (PMC12872463, CC BY 4.0); worth reading as the first relaxed-clock dating of the duplications on both eukaryotic stem lineages, which puts most host-side duplications (cytoskeleton, trafficking, nuclear targeting) before the onset of duplications in genes from the mitochondrial partner at about 2.2 billion years ago, and most other bacterial duplications after it (THEORY-1099). Read it knowing that each date is a maximum age for its paralogues' functions and many intervals reach below 2.2 billion years; that equating the onset of symbiont-gene duplication with endosymbiosis is argued, not tested; that the priors let archaeal duplications be older than any alphaproteobacterial one; and that the authors cannot order phagocytosis and the mitochondrion, though the abstract lists phagocytotic machinery among the features that came first.
Version3
Tagsendosymbiosis, natural-sciences
Cited as “paper” byNOTE-1234 — Kay et al. — Dated gene duplications and the assembly of eukaryotes
Cited as “source” byTHEORY-1099 — On Kay and colleagues' relaxed-clock dating of pre-LECA gene duplications, most duplications in eukaryotic gene families of archaeal origin, including actin, tubulin, vesicle-trafficking and nuclear-targeted families, predate the onset of duplications in genes of alphaproteobacterial origin at about 2.2 billion years ago, which the authors take as the start of mitochondrial endosymbiosis, so the host was elaborating its cytoskeleton, endomembranes and nuclear machinery before the mitochondrion; each date is a maximum age for its paralogues' functions, many intervals reach below 2.2 billion years, and the order of phagocytosis and the mitochondrion is left open, THEORY-1203 — The host lineage elaborated its cytoskeleton, endomembrane system and nuclear machinery before mitochondrial endosymbiosis began, about 2.2 billion years ago: most pre-LECA duplications in eukaryotic gene families of archaeal origin predate it

Graph View

Kay, C. J., Spang, A., Szöllősi, G. J., Pisani, D., Williams, T. A. & Donoghue, P. C. J. (2026). Dated gene duplications elucidate the evolutionary assembly of eukaryotes. Nature 650(8100): 129–140. doi:10.1038/s41586-025-09808-z.

Key takeaways

From the reading, NOTE-1234.

  • A timeline. The archaeal stem (nFECA to LECA) is about twice as long as the alphaproteobacterial one (mFECA to LECA): roughly 1.1 against 0.6 billion years by the authors’ medians.
  • A marker for the mitochondrion. Duplications in genes of alphaproteobacterial origin begin within about 200 million years of mFECA, around 2.2 billion years ago, among them parts of the protein import system. The authors take this onset as the start of endosymbiosis. That equation is argued, not tested.
  • The host came first. 85% of archaeal-origin duplications predate the marker, including ARP2/3, γ-tubulin, Golgi and ER trafficking and nuclear-targeted paralogues (THEORY-1099). Each date bounds a function from above, and many intervals overlap the marker.
  • One partner, not a series. 16 of 19 duplications in non-alphaproteobacterial bacterial genes come after the marker, so the authors argue against serial endosymbiosis. What is dated is duplication, not acquisition.
  • Left open. “our results do not allow us to discriminate between the origin of phagocytosis and the timing of mitochondrial endosymbiosis”. Nothing here bears on when the partners became dependent on each other.

Why this is here

A2 cites it for the timing of mitochondrial acquisition, as one of the three programmes in the live disagreement. Bears on QUESTION-277’s point that the innovations of eukaryogenesis need not share one time or one cause. The reading finds it takes a side on the question’s choice between one merger and a sequence of associations: one endosymbiotic partner, after a long phase of host elaboration, with other bacterial genes arriving by transfer.

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