Colpodella

Colpodella
Scientific classification
Kingdom:	Chromalveolata
Superphylum:	Alveolata
Family:	Colpodellidae Simpson & Patterson, 1996
Genus:	Colpodella Cienkowski, 1865
Type species
Colpodella perforans (Hollande, 1938) Patterson & Zölffel, 1991

Colpodella is a genus of alveolates comprising 5 species, and two further possible species:^[1] They share all the synapomorphies of apicomplexans, but are free-living, rather than parasitic.^[1] This genus was previously known as Spiromonas. This genus was once thought to be a genus of kinetoplastids.

The type species is Colpodella perforans.

Description

These are small (< 20 μm in diameter) flagellated protists. The life cycle of consists of two main stages: flagellated trophozoites and resting cysts.

Morphologically these trophozoites of these species of this genus are very similar to Perkinsus. The motile stages of both genera have a pair of anterior orthogonal flagella, vesicular mitochondrial cristae, inner alveolar membranes and micropores. Some species may also posses a third flagellum. Both Colpodella and Perkinsus species have open sided truncated conoids (known as the rostrum in Colpodella), rhoptries that occupy the length of the cell and smaller micronemes. Both the rhoptries and micronemes arise at the anterior portion of the cell. A three-membraned pellicle lies beneath the plasma membrane and is composed of the endoplasmic reticulum and widely separated microtubules that arise subapically. It is present only in the anterior part of the cell. Some species have extrusive organelles (trichocysts).

Unlike Perkinsus, the Colpodella are free living and are voracious predators of other free living protists. With the rostrum, they penetrate through the cell membrane and consume the prey's cytoplasm. The rostrum is identical in structure and function to the conoid of Perkinsus zoospores. While feeding the protist attaches its anterior portion to the prey. The rostrum then transforms into a ring of microtubules encircling the attachment zone. The cytoplasm of the prey is aspirated and drawn into a large posterior food vacuole. This mode of feeding is known as myzocytosis.

Following feeding species of both genera lose their flagella, become spherical, exhibit a large central vacuole, encyst and divide. The cysts are simple spheres and aside from some sparsely distributed pores, are generally completely devoid of any surface features. One difference in their life cycles is that species of Colpodella produce 4 progeny per cyst while Perkinsus species can produce up to 32 per cyst. Reproduction in this genus is by simple binary fission.

Taxonomy

This family appears to be a sister clade to the Apicomplexa.^[2] Their life style may be representative of the free living ancestors of the Apicomplexa. One significant difference is that this genus, like the Perkinsea, have an open sided conoid while the Apicomplexa which posses a coniod (the Conoidasida) have a closed conoid.

Another genus in this family is Acrocoelus.

• Colpodella edax (Klebs, 1892) Simpson & Patterson, 1996
• Colpodella gonderi (Foissner & Foissner, 1984) Simpson & Patterson, 1996
• Colpodella perforans (Hollande, 1938) Patterson & Zölffel, 1991
• Colpodella pontica
• Colpodella pugnax Cienkowsky, 1865
• Colpodella unguis Patterson & Simpson, 1996
• Colpodella vorax (Kent, 1880) Simpson & Patterson, 1996
• ?Colpodella angusta (Dujardin, 1841) Simpson & Patterson, 1996
• ?Colpodella turpis Simpson & Patterson, 1996

References

1. ^ ^{a b} Alastair G. B. Simpson & David J. Patterson (1996). "Ultrastructure and identification of the predatory flagellate Colpodella pugnax Cienkowski (Apicomplexa) with a description of Colpodella turpis n. sp. and a review of the genus". Systematic Parasitology 33 (3): 187–198. doi:10.1007/BF01531200. 
2. ^ Brian S. Leander, Olga N. Kuvardina, Vladimir V. Aleshin, Alexander P. Mylnikov & Patrick J. Keeling (2003). "Molecular phylogeny and surface morphology of Colpodella edax (Alveolata): insights into the phagotrophic ancestry of apicomplexans" (PDF). Journal of Eukaryotic Microbiology 50 (5): 334–340. doi:10.1111/j.1550-7408.2003.tb00145.x. PMID 14563171. http://www.botany.ubc.ca/bleander/images/Edax.pdf. 

External links

• Colpodella at the Encyclopedia of Life
• Brian S. Leander & Patrick J. Keeling (2003). "Morphostasis in alveolate evolution" (PDF). Trends in Ecology and Evolution 18 (8): 395–402. doi:10.1016/S0169-5347(03)00152-6. http://www.botany.ubc.ca/bleander/images/Leander.pdf.