Descriptions

Outline

Click the species name for a description of the organism

Allomyces macrogynus ATCC 38327

According to traditional taxonomy, Allomyces macrogynus was a member of the Blastocladiales in the Chytridiomycota (chytrids), one of the four major phyla of Fungi. As chytrids develop (in most cases uni-) flagellated zoospores (resembling flagellated cells in animals) at various stages of their life cycle, they are also known as zoosporic fungi. Because the Chytridiomycota are not monophyletic in some phylogenetic analyses (although currently without compelling statistical support), they have been subdivided into three phyla: Blastocladiomycota, Chytridiomycota, and Neocallimastigomycota [1].

Allomyces macrogynus is found worldwide, particularly in aquatic environments of tropical regions. It alternates between isomorphic sporophytic sexual and gametophytic asexual cycles of growth, producing three forms of uniflagellated cells: mitospores (zoospores), meiospores, and male and female gametes [2]. When encysting, these flagellated cells withdraw their flagellum. Bipolar spore germination then leads to the development of a rhizoidal system, and a thallus that branches into hyphae that are separated by pseudoseptae (i.e., they are not closed but contain pores) [2]. The wild-type strain Burma 3-35 (ATCC 38327) is autotetraploid in the sporophytic cycle, and produces diploid gametophytes. Ploidy can be reduced experimentally, which is useful for isolation of mutants and for genetic experiments. For instance, prolonged growth at 35oC or treatment with para-fluoro-phenylalanine reduces diploid cells (28 chromosomes) to haploid (14 chromosomes) [2]. Allomyces has been widely used as a teaching aid, to demonstrate sexual reproduction and alternation of generations.

References:
  1. Hibbett DS, Binder M, Bischoff JF, Blackwell M, Cannon PF, Eriksson OE, Huhndorf S, James T, Kirk PM, Lucking R et al: A higher-level phylogenetic classification of the Fungi. Mycol Res 2007, 111(Pt 5):509-547.
  2. Olson LW: Allomyces - a different fungus. Opera Botanica 1984, 73:1-96.

Capsaspora owczarzaki ATCC 30864

Capsaspora owczarzaki is a filose amoeboid symbiont of the pulmonate snail Biomphalaria glabrata. Recent molecular phylogenetic analyses have shown that Capsaspora owczarzaki is one of several unicellular lineages that branch as a sister-group to multicellular Metazoa. (1-4, see Figure). Capsaspora occupies a pivotal phylogenetic position between choanoflagellate protists (the closest relatives of Metazoa), and other opisthokonts (such as nucleariids and Fungi). Comparing its genome to these organisms will help unravel the evolutionary history of genes key to multicellularity and animal development. In addition to its important phylogenetic position, Capsaspora owczarzaki has relevance to human health as its host, B. glabrata, is also the intermediate host of the digenean flatworm Schistosoma mansoni, the causative agent of widespread schistosomiasis in humans. According to the World Health Organization, more than 600 million people are currently at risk for infection by Schistosoma, most of them in developing countries (WHO Expert Committee, 1993). Capsaspora owczarzaki not only parasitizes the intermediate host of S. mansoni but has also been found to attack and kill the sporocysts of this worm living inside the snail (5). Thus, the genome sequence of Capsaspora may offer significant insights into genes implicated in the host-schistosome relationship. More importantly, the genome sequence of Capsaspora will be an important step in understanding the molecular basis for the anti-parasitic activity of this organism.

References:

  1. I. Ruiz-Trillo, Y. Inagaki, L.A. Davis, S. Sperstad, B. Landfald, A.J. Roger: Capsaspora owczarzaki is an independent opisthokont lineage. Curr Biol 14(22) (2004) R946-947.
  2. I. Ruiz-Trillo, C.E. Lane, A.J.M., A.J. Roger: Insights into the evolutionary origin and genome architecture of the unicellular opisthokonts Capsaspora owczarzaki and Sphaeroforma arctica. Journal of Eukaryotic Microbiology 53 (2006) 1-6.
  3. I. Ruiz-Trillo, A.J. Roger, G. Burger, M.W. Gray, B.F. Lang: A phylogenomic investigation into the origin of metazoa. Mol Biol Evol 25 (2008) 664-672.
  4. K. Shalchian-Tabrizi, M.A. Minge, M. Espelund, R. Orr, T. Ruden, K.S. Jakobsen, T. Cavalier-Smith: Multigene phylogeny of choanozoa and the origin of animals. PLoS ONE 3 (2008) e2098.
  5. A. Owczarzak, H.H. Stibbs, and C.J. Bayne: The destruction of Schistosoma mansoni mother sporocysts in vitro by amoebae isolated from Biomphalaria glabrata: an ultrastructural study. J Invertebr Pathol 35 (1980) 26-33.

Spizellomyces punctatus DAOM BR117

S. punctatus is the type species of the fungal genus Spizellomyces, which is in the phylum Chytridiomycota (chytrids) [1]. Like all chytrids, Spizellomyces produces uniflagellated zoospores during its reproductive cycle, but in contrast to other zoosporic fungi (e.g. Allomyces), spizellomycetalean zoospores can be amoeboid while actively swimming, and the flagellar insertion site may move to a lateral position [2].

Spizellomyces species are exclusively terrestrial [3]. They are common in soil and of importance in terrestrial ecosystems - with both beneficial and detrimental impacts - found in association with a range of mycorrhizal fungi, mildew, plants and soil nematodes [4, 5]. In biochemical research, S. punctatus has gained attention because of the presence of mitochondrial 5' tRNA editing [6], a form of post-transcriptional RNA processing previously only known from the unrelated amoeboid protist Acanthamoeba castellanii. The RNA editing activities of both Acanthamoeba and Spizellomyces have been partially purified, biochemically characterized, and compared [7-9].

References:
  1. Hibbett DS, Binder M, Bischoff JF, Blackwell M, Cannon PF, Eriksson OE, Huhndorf S, James T, Kirk PM, Lucking R et al: A higher-level phylogenetic classification of the Fungi. Mycol Res 2007, 111(Pt 5):509-547.
  2. Barr DJS: Cytological variation in zoospores of Spizellomyces (Chytridiomycetes). Can J Bot 1984, 62:1202-1208.
  3. Barr DS: An outline for the reclassification of the Chytridiales, and for a new order, the Spizellomycetales. Can J Biochem 1980, 58:2380-2394.
  4. Lozupone CA, Klein DA: Molecular and cultural assessment of chytrid and Spizellomyces populations in grassland soils. Mycologia 2002, 94:411-420.
  5. Paulitz TC, Menge JA: Is Spizellomyces punctatum a parasite of vesicular-arbuscular mycorrhizal fungi? Mycologia 1984, 76:99-107.
  6. Laforest MJ, Roewer I, Lang BF: Mitochondrial tRNAs in the lower fungus Spizellomyces punctatus: tRNA editing and UAG 'stop' codons recognized as leucine. Nucleic Acids Res 1997, 25(3):626-632.
  7. Bullerwell CE, Gray MW: In vitro characterization of a tRNA editing activity in the mitochondria of Spizellomyces punctatus, a chytridiomycete fungus. J Biol Chem 2005, 280(4):2463-2470.
  8. Lonergan KM, Gray MW: Editing of transfer RNAs in Acanthamoeba castellanii mitochondria. Science 1993, 259(5096):812-816.
  9. Price DH, Gray MW: A novel nucleotide incorporation activity implicated in the editing of mitochondrial transfer RNAs in Acanthamoeba castellanii. RNA 1999, 5(2):302-317.

Salpingoeca rosetta [formerly known as Proterospongia sp. ATCC 50818]

Choanoflagellates are free-living unicellular and colonial flagellates considered to be the closest living relatives of the animals [1,2]. Therefore, understanding choanoflagellate biology can illuminate the evolution of multicellularity in the animal lineage. Choanoflagellate cell morphology is characterized by an ovoid cell body 3-10 μm in diameter with a single apical flagellum encircled by a collar of microvilli [1,3]. Movement of the flagellum creates water currents that can propel free-swimming choanoflagellates through the water column as well as trap bacterial prey against the collar of microvilli. As bacterial predators, choanoflagellates are a critical link between trophic levels within the global carbon cycle [3].

Salpingoeca rosetta was chosen for genome sequencing because it undergoes a series of morphological transitions during the differentiation and development of both solitary and colonial forms [4]. Solitary cells are found both in the water column and attached to substrates. Colonies of 4-20 cells form in the water column and are attached to one another at the cell body. The sequencing of the Salpingoeca genome enables exploration into the molecular mechanisms that mediate the choanoflagellate colony formation and allows the testing of hypotheses about the origin of animals.

References:
  1. B.S.C. Leadbeater: Choanoflagellate evolution: the morphological perspective. Protistology 5 (4) (2008) 256-267.
  2. M. Carr, B. S. C. Leadbeater, R. Hassan, M. Nelson, and S. L. Baldauf: Molecular phylogeny of choanoflagellates, the sister group to Metazoa. PNAS 105(43) (2008) 16641-16646.
  3. N. King: Choanoflagellates Current Biology 15(4) (2005) 113.
  4. N. King, C.T. Hittinger, S.B. Carroll: Evolution of key cell signaling and adhesion protein families predates animal origins. Science 301(5631) (2003) 361-363

Thecamonas trahens ATCC 50062 [formerly known as Amastigomonas sp. ATCC 50062]

Apusozoa (apusomonads) are unicellular, biflagellate, bacterivorous eukaryotes occurring worldwide, mainly in marine habitats but also in freshwater and soil. They are able to glide on surfaces (in search of food bacteria) by means of their posterior flagellum. Food is ingested using pseudopodia that are produced at the ventral cell surface. According to phylogenetic analyses (1, 2), apusomonads are (arguably) the closest neighbour to opisthokonts (animals plus fungi, together with their protist relatives such as choanoflagellates and nucleariids (3-5)). The current genome project will help with confirming the phylogenetic position of Apusozoa, and with the evolutionary tracing of animal and fungal traits - including regulatory and developmental principles that are the basis for multicellularity in animals and fungi (6). Thecamonas trahens ATCC 50062 was chosen for genome sequencing among the traditional, bona fide Apusozoa. It grows robustly to high densities, without leaving large amounts of bacterial food that would interfere with biochemical experimentation.

References:
  1. Cavalier-Smith T & Chao EE (2010) Protist, in press.
  2. Kim E, Simpson AG, & Graham LE (2006) Mol Biol Evol 23, 2455-2466.
  3. Lang BF, O'Kelly C, Nerad T, Gray MW, & Burger G (2002) Curr Biol 12, 1773-1778.
  4. Steenkamp ET, Wright J, & Baldauf SL (2006) Mol Biol Evol 23, 93-106.
  5. Liu Y, Steenkamp ET, Brinkmann H, Forget L, Philippe H, & Lang BF (2009) BMC Evol Biol 9, 272.
  6. Ruiz-Trillo I, Burger G, Holland PW, King N, Lang BF, Roger AJ, & Gray MW (2007) Trends Genet 23, 113-118.

Sphaeroforma arctica JP610

Sphaeroforma arctica is a protist that was isolated from the arctic marine amphipod Gammarus setosus (1). Molecular phylogenetic analyses show that Sphaeroforma arctica is a member of the ichthyosporeans, a lineage that branches close to multicellular animals (Metazoa) (2, 3). The ichthyosporeans occupy a pivotal phylogenetic position either as sister group to Capsaspora+Ministeria or as sister group to a clade comprising Capsaspora, Ministeria, Choanoflagellata, and Metazoa (3,4). Comparing the genome sequence of S. arctica to those of the latter organisms will help unravel the evolutionary history of genes key to multicellularity and animal development.

In addition to its important phylogenetic position, Sphaeroforma arctica has the capacity to form "multicellular-like" colonies (2,5). These pseudo-multicellular colonies may comprise more than 30 cells that will be released to the media. The genome sequence of S. arctica may provide insights into this type of "multicellularity" and the transition into the more complex pattern of metazoan multicellularity.

References:
  1. J-P. Jostensen, S. Sperstad, S. Johansen, B. Landfald: Molecular-phylogenetic, structural and biochemical features of a cold-adapted, marine ichthyosporean near the animal-fungal divergence, described from in vitro cultures. (2002). European Journal of Protistology 38: 93-104.
  2. I. Ruiz-Trillo, C.E. Lane, A.J.M., A.J. Roger, Insights into the evolutionary origin and genome architecture of the unicellular opisthokonts Capsaspora owczarzaki and Sphaeroforma arctica. (2006). Journal of Eukaryotic Microbiology 53: 1-6.
  3. I. Ruiz-Trillo, A.J. Roger, G. Burger, M.W. Gray, B.F. Lang. A phylogenomic investigation into the origin of metazoa. (2008). Mol Biol Evol 25: 664-672.
  4. K. Shalchian-Tabrizi, M.A. Minge, M. Espelund, R. Orr, T. Ruden, K.S. Jakobsen, T. Cavalier-Smith. Multigene phylogeny of choanozoa and the origin of animals. (2008). PLoS ONE 3 e2098.
  5. I. Ruiz-Trillo, G. Burger, PW. Holland, N. King, BF. Lang, AJ. Roger, MW. Gray: The origins of multicellularity: a multi-taxon genome initiative. (2007). Trends Genet 23:113-118.

Mortierella verticillata NRRL 6337

TBA.