EVOLUTION OF THE HYDROGENOSOME

Since its discovery almost 25 years ago the enigmatic hydrogenosome, a redox organelle of anaerobic unicellular eukaryotes, has puzzled evol utionists as to its origin and function. Synthesis of recent molecular , physiological and morphological studies now favours the hypothesis t hat hydrogenosomes derived from a modification of pre-existing mitocho ndria, and argues against the previously held view that the hydrogenos ome had a polyphyletic origin. These data provide evidence for a more ancient origin of mitochondria than hitherto thought.