Mixotricha

NCBI: Taxonomy Genome

Mixotricha paradoxa. Photo by Dean Soulia.

Classification

Higher order taxa

Eukaryota; Parabasalidea; Trichomonada; Trichomonadida; Devescovinidae

Species

Mixotricha paradoxa

Description and Significance

Mixotricha are contained within the phylum Parabasalidea. Unlike Trichomonas, however, Mixotricha are not pathogenic in humans. They instead are found in the gut of the Austrailian termite Mastotermes darwiniensis. Because of their morphological characteristics, Mixotricha are considered important in the history of nucleated cells.

Genome Structure

According to Margulis and Sagan (2001), Mixotricha have five genomes because they form symbiotic relationships with so many other organisms. They consider Mixotricha paradoxa the poster organism for symbiogenesis. Hosting four types of bacteria, Mixotricha is a composite of five organisms with five different genomes, which is why Hunt et. al. (2001, 2002) insist that this organism has five genomes.

Cell Structure and Metabolism

Mastotermes darwiniensis. Ecowatch.

Mixotricha has a tear-shaped cell body. There are four anterior flagella. One of the four is recurrent and not adherent to the body. The flagella are weak and serve more for steering purposes than actual movement. Mixotricha also uses cilia for locomotion. These cilia are actually spirochetes (a type of spiral bacteria) attached to the cell surface. In addition, there is an ordered pattern of rod shaped bacteria on the cell body. Mixotricha lack mitochondira, but have bacterial endosymbionts to fulfill the role. There are a total of four types of bacteria that are a part of the Mixotricha body.

Mixotricha are heterotrophs. They are wood-digesting protists, living inside the gut of Mastotermes darwiniensis and helping it process the wood it ingests.

Ecology

Mixotricha paradoxa forms symbiotic relationships with the termite Mastotermes darwiniensis. The Mixotricha are organized as layers of tissue. Although they pose no pathogenic threat to humans, they are indirectly harmful. Without their presence in the termite gut, the termites would die. Because Mixotricha keep the Mastotermes darwiniensis species intact, they are harmful in an indirect way.

Mixotricha paradoxa. Microbiological Garden, "Movement Symbiosis."

References

Brugerolle G. "Devescovinid features, a remarkable surface cytoskeleton, and epibiotic bacteria revisited in Mixotricha paradoxa, a parabasalid flagellate." Protoplasma. 2004 Oct;224(1-2):49-59.

The Ecowatch Project. "Isoptera: termites." Accessed 28 June 2005.

Margulis, Lynn and Dorion Sagan. "The Beast With Five Genomes." Natural History Magazine. June 2001. Accessed 28 June 2005.

Margulis, Lynn, Dorion Sagan, and Jessica H. Whiteside. "From cells to cities: The evolution of composite individuality - early life leaves its record in the rocks." 10 February 2002. Accessed 28 June 2005.

Microbiological Garden. "Movement Symbiosis." Accessed 28 June 2005.

Wenzel, Marika, Renate Radek, Guy Brugerolle, Helmut König. "Identification of the ectosymbiotic bacteria of Mixotricha paradoxa involved in movement symbiosis." Europ. J. Protistol. 39, 11–23 (2003).

Wier, Andrew, Michael Dolan, David Grimaldi, Ricardo Guerrero, Jorge Wagensberg, and Lynn Margulis. "Spirochete and protist symbionts of a termite (Mastotermes electrodominicus) in Miocene amber." PNAS. 5 February 2002;99(3):1410-1413.