MIXOTRICHA PARADOXA: AN ARCHAEZOAN EUKARYOTIC MODEL ORGANISM

摘要

One of the larger wood-ingesting flagellates in the hindgut of the most primitive existing termite species Mastotermes darwiniensis is the Archaezoon Mixo-tricha paradoxa, a member of the order Trichomona-dida. The pear-shaped cells are about 500 μm long and 250 μm in diameter. The surface of Mixotricha paradoxa shows a highly ordered pattern of rod shaped bacteria and in addition it is covered by a dense carpet of spirochetes with the exception of the posterior ingesti-ve zone. The rod shaped bacteria and the spirochetes are attached to regularly arranged protrusions of the cell surface, the so called brackets. So far, it is not possible to cultivate neither Mixotricha paradoxa nor its ectosymbiotic spirochetes or rod-shaped bacteria. As a consequence there is no reliable information about their systematic position. In this study we examined the phylogenetic position of the ectosymbiotic spirochetes and the rod shaped bacterium of Mixotricha paradoxa.