''Colpodella'' is a

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

alveolate The alveolates (meaning "pitted like a honeycomb") are a group of protists, considered a major unranked clade or superphylum within Eukaryota. They are currently grouped with the Stramenopiles and Rhizaria among the protists with tubulocristate ...

s comprising five

species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...

, and two further possible species: They share all the

synapomorphies In phylogenetics, an apomorphy (or derived trait) is a novel character or character state that has evolved from its ancestral form (or plesiomorphy). A synapomorphy is an apomorphy shared by two or more taxa and is therefore hypothesized to ...

apicomplexa The Apicomplexa (also called Apicomplexia; single: apicomplexan) are organisms of a large phylum of mainly parasitic alveolates. Most possess a unique form of organelle structure that comprises a type of non-photosynthetic plastid called an ap ...

ns, but are free-living, rather than

parasitic Parasitism is a close relationship between species, where one organism, the parasite, lives (at least some of the time) on or inside another organism, the host, causing it some harm, and is adapted structurally to this way of life. The ent ...

. Many members of this genus were previously assigned to a different genus - '' Spiromonas''. The

type species In International_Code_of_Zoological_Nomenclature, zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the spe ...

is ''

Colpodella pugnax ''Colpodella'' is a genus of Alveolata, alveolates comprising five species, and two further possible species: They share all the synapomorphy, synapomorphies of apicomplexans, but are free-living, rather than parasitism, parasitic. Many members o ...

'' Cienkowski 1865.

Description

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

trophozoite A trophozoite (G. ''trope'', nourishment + ''zoon'', animal) is the activated, feeding stage in the life cycle of certain protozoa such as malaria-causing ''Plasmodium falciparum'' and those of the ''Giardia'' group. The complementary form of the t ...

s and

cysts A cyst is a closed Wikt:sac, sac, having a distinct Cell envelope, envelope and cell division, division compared with the nearby Biological tissue, tissue. Hence, it is a cluster of Cell (biology), cells that have grouped together to form a sac ...

, which are the reproductive stage in the life cycle. Morphologically the trophozoites of ''Colpodella'' are similar to ''

Perkinsus ''Perkinsus'' is a genus of alveolates in the phylum Perkinsozoa. The genus was erected in 1978 to better treat its type species, '' Perkinsus marinus'', known formerly as ''Dermocystidium marinum''. These are parasitic protozoans that infect ...

zoospore A zoospore is a motile asexual spore that uses a flagellum for locomotion in aqueous or moist environments. Also called a swarm spore, these spores are created by some protists, bacteria, and fungi to propagate themselves. Certain zoospores are ...

s, although the two taxa are not specifically related. The motile stages of both genera have a pair of anterior orthogonal

flagella A flagellum (; : flagella) (Latin for 'whip' or 'scourge') is a hair-like appendage that protrudes from certain plant and animal sperm cells, from fungal spores ( zoospores), and from a wide range of microorganisms to provide motility. Many pr ...

, vesicular mitochondrial cristae, inner alveolar membranes and micropores. Both ''Colpodella'' and ''Perkinsus'' species have open sided truncated conoids (sometimes called pseudoconoids), rhoptries that occupy the length of the cell and smaller

microneme Micronemes are secretory organelles, possessed by parasitic apicomplexans. Micronemes are located on the apical third of the protozoan body. They are surrounded by a typical unit membrane. On electron microscopy they have an electron-dense ma ...

s. Both the rhoptries and micronemes arise at the anterior portion of the cell. A three-layered pellicle lies beneath the

plasma membrane The cell membrane (also known as the plasma membrane or cytoplasmic membrane, and historically referred to as the plasmalemma) is a biological membrane that separates and protects the interior of a cell from the outside environment (the extr ...

and is otherwise composed of the alveolar membranes and widely separated

microtubule Microtubules are polymers of tubulin that form part of the cytoskeleton and provide structure and shape to eukaryotic cells. Microtubules can be as long as 50 micrometres, as wide as 23 to 27 nanometer, nm and have an inner diameter bet ...

s that arise subapically. Some species have extrusive organelles (

trichocyst A trichocyst is an organelle found in certain ciliates and dinoflagellate The Dinoflagellates (), also called Dinophytes, are a monophyletic group of single-celled eukaryotes constituting the phylum Dinoflagellata and are usually considered pr ...

s). Unlike ''Perkinsus'', ''Colpodella'' are free-living and are voracious predators of other free-living

protist A protist ( ) or protoctist is any eukaryotic organism that is not an animal, land plant, or fungus. Protists do not form a natural group, or clade, but are a paraphyletic grouping of all descendants of the last eukaryotic common ancest ...

s. Most species apparently penetrate through the cell membrane and consume the prey's cytoplasm—this mode of feeding is known as

myzocytosis Myzocytosis (from Greek: myzein, (') meaning "to suck" and kytos (') meaning "container", hence referring to "cell") is a method of feeding found in some heterotrophic organisms. It is also called "cellular vampirism" as the predatory cell pierce ...

. While feeding the predator attaches its anterior portion—the rostrum—to the prey. The rostrum contains the pseudoconoid, which transforms into a ring of

s encircling the attachment zone. The cytoplasm of the prey is then drawn into a large posterior food

vacuole A vacuole () is a membrane-bound organelle which is present in Plant cell, plant and Fungus, fungal Cell (biology), cells and some protist, animal, and bacterial cells. Vacuoles are essentially enclosed compartments which are filled with water ...

. Following feeding cells lose their flagella, become spherical, encyst and divide (i.e. reproduce). The

are simple spheres. The food vacuole appears as a large central

in the cyst; as division progresses the remnant vacuole material is reduced to a residual body. Typically Colpodella divides into four daughter cells (sometimes just two). This is in contrast to true Apicomplexa and ''Perkinsus'', which typically produce many more daughter cells during reproduction—''Perkinsus'' species can produce up to 32 cells, for example, while ''Toxoplasma'' produces 128. The daughter cells grow flagella, the cyst wall ruptures, and the cells swim away, leaving the residual body behind. A possible sexual process has been observed in at least two species.

Taxonomy

This family appears to be a sister clade to the Apicomplexa. Their life style may be representative of the free living ancestors of the Apicomplexa. One significant difference is that this genus, like the

Perkinsea Perkinsids are single-celled protists that live as intracellular parasites of a variety of other organisms. They are classified as the class Perkinsea within the monotypic phylum Perkinsozoa. It is part of the eukaryotic supergroup Alveolata, ...

, have an open sided conoid (pseudoconoid) while the Apicomplexa which possess a conoid (the

Conoidasida Conoidasida is a class of parasitic alveolates in the phylum Apicomplexa. The class was defined in 1988 by Levine and contains two subclasses – the coccidia and the gregarines. All members of this class have a complete, hollow, truncated ...

) have a closed conoid. Another genus in this family is '' Acrocoelus''. Species currently within genus: * ''

Colpodella edax ''Colpodella'' is a genus of alveolates comprising five species, and two further possible species: They share all the synapomorphies of apicomplexans, but are free-living, rather than parasitic. Many members of this genus were previously assigned ...

'' (Klebs 1892) Simpson & Patterson 1996 * '' Colpodella pseudoedax'' Mylnikov & Mylnikov 2007 * ''

'' Cienkowsky 1865 non Simpson & Patterson 1996 * '' Colpodella angusta'' (Dujardin 1841) Simpson & Patterson 1996 'Dingensia angusta'' (Dujardin 1841) Patterson & Zoelffel 1991">Dingensia_angusta.html" ;"title="'Dingensia angusta">'Dingensia angusta'' (Dujardin 1841) Patterson & Zoelffel 1991 Species transferred to other genera: * ''Colpodella gonderi'' (Foissner & Foissner 1984) Simpson & Patterson 1996 as ''Microvorax gonderi'' (Foissner & Foissner 1984) Cavalier-Smith 2017 * ''Colpodella perforans'' (Hollande 1938) Patterson & Zölffel 1991 as ''Chilovora perforans'' (Hollande 1938) Cavalier-Smith & Chao 2004 * ''Colpodella pontica'' Mylnikov 2000 as '' Voromonas pontica'' (Mylnikov 2000) Cavalier-Smith & Chao 2004 * ''Colpodella pugnax'' Simpson & Patterson 1996 non Cienkowsky 1865 as '' Algovora pugnax'' (Simpson & Patterson 1996) Cavalier-Smith & Chao 2004 * ''Colpodella tetrahymenae'' Cavalier-Smith 2004 as '' Microvorax tetrahymenae'' (Cavalier-Smith & Chao 2004) Cavalier-Smith 2017 * ''Colpodella turpis'' Simpson & Patterson 1996 as '' Algovora turpis'' (Simpson & Patterson 1996) Cavalier-Smith & Chao 2004 * ''Colpodella unguis'' Patterson & Simpson 1996 as '' Colpovora unguis'' (Patterson & Simpson 1996) Cavalier-Smith 2017 * ''Colpodella vorax'' (Kent, 1880) Simpson & Patterson, 1996 as '' Dinomonas vorax'' Kent 1880

Clinical

These organisms are not normally considered to be human pathogens. However, a report of an infection of the

erythrocyte Red blood cells (RBCs), referred to as erythrocytes (, with -''cyte'' translated as 'cell' in modern usage) in academia and medical publishing, also known as red cells, erythroid cells, and rarely haematids, are the most common type of blood ce ...

s in a Chinese woman with a deficiency of

natural killer cell Natural killer cells, also known as NK cells, are a type of cytotoxic lymphocyte critical to the innate immune system. They are a kind of large granular lymphocytes (LGL), and belong to the rapidly expanding family of known innate lymphoid cells ...

s has been reported.Yuan CL, Keeling PJ, Krause PJ, Horak A, Bent S, Rollend L, Hua XG (2012) ''Colpodella'' spp.-like parasite infection in woman, China. Emerg Infect Dis 18(1):125-127 doi: 10.3201/eid1801.110716

References

External links

* {{Taxonbar, from=Q5149298 Apicomplexa genera