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The hydrogen hypothesis for the first eukaryote


A new hypothesis for the origin of eukaryotic cells is proposed, based on the comparative biochemistry of energy metabolism. Eukaryotes are suggested to have arisen through symbiotic association of an anaerobic, strictly hydrogen-dependent, strictly autotrophic archaebacterium (the host) with a eubacterium (the symbiont) that was able to respire, but generated molecular hydrogen as a waste product of anaerobic heterotrophic metabolism. The host's dependence upon molecular hydrogen produced by the symbiont is put forward as the selective principle that forged the common ancestor of eukaryotic cells.

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Figure 1: Schematic summary of forms of energy metabolism among heterotrophic eukaryotes (see refs 18 and19for details).
Figure 2: Hypothetical model to derive the ancestral state of eukaryotic energy metabolism put forward here, invoking strict dependence of the host upon waste products of the symbiont's anaerobic heterotrophy (see text).


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We thank H. Brinkmann, M. Embley, K. Henze, R. Herrmann, R. Hensel, D.Oesterheld and L. Sánchez for critical comments on the manuscript and gratefully acknowledge financial support from the Deutsche Forschungsgemeinschaft (W.M.) and the National Institutes of Health (M.M.).

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Correspondence to William Martin or Miklós Müller.

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Martin, W., Müller, M. The hydrogen hypothesis for the first eukaryote. Nature 392, 37–41 (1998).

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