Hydrogen hypothesis
From Free net encyclopedia
The hydrogen hypothesis is a model proposed by William Martin and Miklos Muller in 1998 that describes a possible way in which the mitochondrion developed in the first eukaryotic cell within the endosymbiotic theory framework.
According to the hydrogen hypothesis the first eukaryotic cell did not appear as a consequence of a primitive host cell engulfing a primitive bacteria, which wasn't fully digested and eventually became the mitochondrion as the current endosymbiotic theory suggests. It claims instead that the host - a methanogen archaea which used hydrogen and carbon dioxide, producing methane - and a primitive eubacteria, the future mitochondrion, which produced hydrogen and carbon dioxide as byproducts of anaerobic respiration, started a symbiotic relationship based on their byproducts.
The idea originated when Martin assisted at a talk by Muller on hydrogenosomes. These occur in anaerobic eukaryotic cells replacing the mitochondrial ATP production role, and producing large amounts of hydrogen and carbon dioxide. One of Muller's slides presented a cluster of methanogens around a hydrogenosome inside a eukaryotic cell they had invaded.
If the hypothesis is correct it would imply that eukaryotes are very close to archaea and appeared relatively late. This contradicts the current view which states that archaea and eukarya split before the modern groups of archaea appeared.