Molecular Biology and Evolution 17:251-258 (2000)
© 2000 Society for Molecular Biology and Evolution
Articles |
Multiple Acquisition of Methanogenic Archaeal Symbionts by Anaerobic Ciliates


*Department of Microbiology and Evolutionary Biology, Faculty of Science,
and
CAOS/CAMM Center, University of Nijmegen, Nijmegen, the Netherlands;
and
Biologisches Institut, Universitat Stuttgart, Stuttgart, Germany
Anaerobic heterotrichous ciliates (Armophoridae and Clevelandellidae) possess hydrogenosomes that generate molecular hydrogen and ATP. This intracellular source of hydrogen provides the basis for a stable endosymbiotic association with methanogenic archaea. We analyzed the SSU rRNA genes of 18 heterotrichous anaerobic ciliates and their methanogenic endosymbionts in order to unravel the evolution of this mutualistic association. Here, we show that the anaerobic heterotrichous ciliates constitute at least three evolutionary lines. One group consists predominantly of gut-dwelling ciliates, and two to three, potentially four, additional clades comprise ciliates that thrive in freshwater sediments. Their methanogenic endosymbionts belong to only two different taxa that are closely related to free-living methanogenic archaea from the particular ecological niches. The close phylogenetic relationships between the endosymbionts and free-living methanogenic archaea argue for multiple acquisitions from environmental sources, notwithstanding the strictly vertical transmission of the endosymbionts. Since phylogenetic analysis of the small-subunit (SSU) rRNA genes of the hydrogenosomes of these ciliates indicates a descent from the mitochondria of aerobic ciliates, it is likely that anaerobic heterotrichous ciliates hosted endosymbiotic methanogens prior to their radiation. Therefore, our data strongly suggest multiple acquisitions and replacements of endosymbiotic methanogenic archaea during their host's adaptation to the various ecological niches.
![]()
CiteULike
Connotea
Del.icio.us What's this?
This article has been cited by other articles:
![]() |
K. W. A. van Grinsven, S. Rosnowsky, S. W. H. van Weelden, S. Putz, M. van der Giezen, W. Martin, J. J. van Hellemond, A. G. M. Tielens, and K. Henze Acetate:Succinate CoA-transferase in the Hydrogenosomes of Trichomonas vaginalis: IDENTIFICATION AND CHARACTERIZATION J. Biol. Chem., January 18, 2008; 283(3): 1411 - 1418. [Abstract] [Full Text] [PDF] |
||||
![]() |
J. M. Brown, N. A. Fine, G. Pandiyan, R. Thazhath, and J. Gaertig Hypoxia Regulates Assembly of Cilia in Suppressors of Tetrahymena Lacking an Intraflagellar Transport Subunit Gene Mol. Biol. Cell, August 1, 2003; 14(8): 3192 - 3207. [Abstract] [Full Text] [PDF] |
||||
![]() |
C. G. Kurland and S. G. E. Andersson Origin and Evolution of the Mitochondrial Proteome Microbiol. Mol. Biol. Rev., December 1, 2000; 64(4): 786 - 820. [Abstract] [Full Text] [PDF] |
||||


