Colponema

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Colponema
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Clade: Diaphoretickes
Clade: SAR
Clade: Alveolata
Order: Colponemida
Family: Colponemidae
Genus: Colponema
von Stein 1878
Synonyms
  • Stroemia Skvortzov & Noda 1968 non Vahl 1790 non Hagen 1908 non Oudemans 1923

Colponema is a genus of single-celled flagellates that feed on eukaryotes in aquatic environments and soil. The genus contains 6 known species and has not been thoroughly studied. [1] Colponema has two flagella which originate just below the anterior end of the cell. One extends forwards and the other runs through a deep groove in the surface and extends backwards. [2] Colponema is a predator that feeds on smaller flagellates using its ventral groove. [1] Like many other alveolates, they possess trichocysts, tubular mitochondrial cristae, and alveoli. [2] It has been recently proposed that Colponema may be the sister group to all other alveolates. [2] [3] [4] The genus could help us understand the origin of alveolates and shed light on features that are ancestral to all eukaryotes. [1]

Etymology

Colponema is a compound of the Greek words 'kolpos' and 'nema'. 'Kolpos' means fold or hollow and is likely referring to the pronounced groove present in Colponema. 'Nema' means thread and alludes to the organism's recurrent flagellum, which originates at the anterior end of the cell and passes through the groove. [2] Although the initial description of Colponema does not explicitly provide an explanation of its etymology, the publication does highlight the organism's large abdominal groove and the figures show the flagellum going through it. [5]

History

Colponema was first described by Dr. Friedrich Ritter Stein in 1878 in "Der Organismus der Flagellaten", which contained a number of protist species descriptions. [5] Colponema loxodes was described in just one line, which stated that there was a large abdominal groove and made reference to a figure depicting the organism from different angles. [5] Following the initial conception of the genus, new species C. globosum and C. symmetricum were described. [6] [7] The ultrastructure of colponemids was not discussed in detail until 1975 with Mignot and Brugerolle's study of C. loxodes. [8] The remaining species, C. edaphicum, C. vietnamica, and C. marisrubri were introduced to the genus in recent years, and phylogenetic analyses allowed researchers to use Colponema to ask questions about alveolate evolution. [1] [3] [4]

Habitat and ecology

Colponema is a single-celled predator that has been found in lakes, soil, reservoirs, marine sediment, and sewage waters. It is an obligate eukaryovore, meaning that it can only feed on other eukaryotes such as bodonids and does not tend to eat larger prey or bacteria. [1] Their primary role in ecosystems is controlling the numbers of smaller flagellates. [1] It is likely that larger eukaryotes and small animals are its primary predators, but the details of Colponema's ecological role have yet to be characterized because it is relatively rare and difficult to culture. [1] The genus' scarcity further supports its position as a predator in the microbial food chain; predators are often present in smaller numbers because large amounts of prey are needed to sustain their population. [1]

Description

Colponema is a colorless biflagellate with a pronounced ventral feeding groove. [1] Cell size ranges from 4-14 μm in width and 8-17 μm in length and they have an oval shape that narrows at the anterior end. [1] The cells have 1 μm long toxicysts, a type of organelle that is extruded from the cell and are used to immobilize prey. [1] Species of Colponema vary in the presence of a contractile vacuoles, degree of dorsoventral flattening, and the length of flagella. [1]

The flagella are heterodynamic and originate just below the anterior of the cell. One flagellum points towards the anterior end of the cell and has mastigonemes near the base. The other has a fold near the base and runs through the cell's feeding groove to point posteriorly. [1] Prey are engulfed whole through the feeding groove and digested in large food vacuoles. [1]  

Similar to other alveolates, the pellicle of Colponema is composed of three membranes and contains inflated cortical alveoli. They also have tubular cristae in their mitochondria. [1] In contrast, the cells do not share important traits that characterize the other groups of alveolates, such as rhoptries, derived ciliature, or palintomy. [1]

No resting stages or sexual reproduction has been observed in culture. [1] Asexual reproduction occurs through longitudinal division, wherein the plane of division is parallel to the groove in the cell. They are only able to divide after engulfing many other eukaryotes. [9]

Importance

From high profile diseases like malaria to maintenance of bacterial communities in water reservoirs, alveolates can have sweeping medical and economic impacts. By looking into lineages that diverged during evolutionary transitions near the origin of alveolates, you can develop a better understanding of how the group evolved. Colponema is very useful to our understanding of alveolate evolution because they were one of the first groups to diverge and display key characters that can be used to compare them to other alveolates. [2] [3] We can use this information to work towards reconstructing the common ancestor to all alveolates and broadening our understanding of these extremely important and widespread organisms. [1]

List of species

Related Research Articles

<span class="mw-page-title-main">Alveolate</span> Superphylum of protists

The alveolates are a group of protists, considered a major clade and superphylum within Eukarya. They are currently grouped with the stramenopiles and Rhizaria among the protists with tubulocristate mitochondria into the SAR supergroup.

Extrusomes are membrane-bound structures in some eukaryotes which, under certain conditions, discharge their contents outside the cell. There are a variety of different types, probably not homologous, and serving various functions.

<span class="mw-page-title-main">Telonemia</span> Phylum of single-celled organisms

Telonemia is a phylum of microscopic eukaryotes commonly known as telonemids. They are unicellular free-living flagellates with a unique combination of cell structures, including a highly complex cytoskeleton unseen in other eukaryotes.

Carpediemonas is genus of Metamonada, and belongs to the group Excavata. This organism is a unicellular flagellated eukaryote that was first discovered in substrate samples from the Great Barrier Reef. Carpediemonas can be found in anaerobic intertidal sediment, where it feeds on bacteria. A feature of this species is the presence of a feeding groove, a characteristic of the excavates. Like most other metamonads, Carpediemonas does not rely on an aerobic mitochondrion to produce energy. Instead, it contains hydrogenosomes that are used to produce ATP. This organism has two flagella: a posterior one used for feeding on the substrate, and an anterior one that moves in a slower sweeping motion. Carpediemonas is assigned to the fornicates, where similar Carpediemonas-like organisms are used in researching the evolution within excavates. Although Carpediemonas is a member of the metamonads, it is unusual in the sense that it is free-living and has three basal bodies.

<i>Colpodella</i> Genus of single-celled organisms

Colpodella is a genus of alveolates comprising 5 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 to a different genus - Spiromonas.

<span class="mw-page-title-main">Holozoa</span> Clade containing animals and some protists

Holozoa is a clade of organisms that includes animals and their closest single-celled relatives, but excludes fungi and all other organisms. Together they amount to more than 1.5 million species of purely heterotrophic organisms, including around 300 unicellular species. It consists of various subgroups, namely Metazoa and the protists Choanoflagellata, Filasterea, Pluriformea and Ichthyosporea. Along with fungi and some other groups, Holozoa is part of the Opisthokonta, a supergroup of eukaryotes. Choanofila was previously used as the name for a group similar in composition to Holozoa, but its usage is discouraged now because it excludes animals and is therefore paraphyletic.

<i>Amastigomonas</i> Genus of protozoa with two flagella

Amastigomonas is a genus of protists belonging to a lineage of biciliated zooflagellates known as Apusomonadida. It was first described in 1931 by Henri de Saedeleer. The current use of Amastigomonas is as a descriptive archetype, with no phylogenetic or taxonomic implications. The term "Amastigomonas-like" is used to refer to all apusomonads that lack the 'derived' characteristics of Apusomonas.

Voromonas is a genus of predatory alveolates. The genus and species were described by Mylnikov in 2000. It was originally described as Colpodella pontica but was later renamed by Cavalier-Smith and Chao in 2004.

<span class="mw-page-title-main">Collodictyonidae</span> Family of aquatic microorganisms

Collodictyonidae is a group of aquatic, unicellular eukaryotic organisms with two to four terminal flagella. They feed by phagocytosis, ingesting other unicellular organisms like algae and bacteria. The most remarkable fact of this clade is its uncertain position in the tree of life.

Diphylleia rotans is a eukaryotic microorganism. It is notable for having a gene-rich mitochondrial genome, the largest known outside the jakobids.

<i>Chilomastix</i>

Chilomastix is a genus of pyriform excavates within the family Retortamonadidae All species within this genus are flagellated, structured with three flagella pointing anteriorly and a fourth contained within the feeding groove. Chilomastix also lacks Golgi apparatus and mitochondria but does possess a single nucleus. The genus parasitizes a wide range of vertebrate hosts, but is known to be typically non-pathogenic, and is therefore classified as harmless. The life cycle of Chilomastix lacks an intermediate host or vector. Chilomastix has a resistant cyst stage responsible for transmission and a trophozoite stage, which is recognized as the feeding stage. Chilomastix mesnili is one of the more studied species in this genus due to the fact it is a human parasite. Therefore, much of the information on this genus is based on what is known about this one species.

Ancoracysta is a genus of eukaryotic microbes containing the species Ancoracysta twista, a predatory protist that appears to be related to Haptista.

<i>Neobodo</i> Genus of protists

Neobodo are diverse protists belonging to the eukaryotic supergroup Excavata. They are Kinetoplastids in the subclass Bodonidae. They are small, free-living, heterotrophic flagellates with two flagella of unequal length used to create a propulsive current for feeding. As members of Kinetoplastids, they have an evident kinetoplast There was much confusion and debate within the class Kinetoplastid and subclass Bodonidae regarding the classification of the organism, but finally the new genera Neobodo was proposed by Keith Vickerman. Although they are one of the most common flagellates found in freshwater, they are also able to tolerate saltwater Their ability to alternate between both marine and freshwater environments in many parts of the world give them a “cosmopolitan” character. Due to their relatively microscopic size ranging between 4–12 microns, they are further distinguished as heterotrophic nanoflagellates. This small size ratio limits them as bacterivores that swim around feeding on bacteria attached to surfaces or in aggregates.

Petalomonas is a genus of phagotrophic, flagellated euglenoids. Phagotrophic euglenoids are one of the most important forms of flagellates in benthic aquatic systems, playing an important role in microbial food webs. The traits that distinguish this particular genus are highly variable, especially at higher taxa. However, general characteristics such as a rigid cell shape and single emergent flagellum can describe the species among this genus.

Rhodelphis is a single-celled archaeplastid that lives in aquatic environments and is the sister group to red algae and possibly Picozoa. While red algae have no flagellated stages and are generally photoautotrophic, Rhodelphis is a flagellated predator containing a non-photosynthetic plastid. This group is important to the understanding of plastid evolution because they provide insight into the morphology and biochemistry of early archaeplastids. Rhodelphis contains a remnant plastid that is not capable of photosynthesis, but may play a role in biochemical pathways in the cell like heme synthesis and iron-sulfur clustering. The plastid does not have a genome, but genes are targeted to it from the nucleus. Rhodelphis is ovoid with a tapered anterior end bearing two perpendicularly-oriented flagella.

<span class="mw-page-title-main">Cortical alveolum</span> Cellular organelle found in protists

The cortical alveolum is a cellular organelle consisting of a vesicle located under the cytoplasmic membrane, to which they give support. The term "corticate" comes from an evolutionary hypothesis about the common origin of kingdoms Plantae and Chromista, because both kingdoms have cortical alveoli in at least one phylum. At least three protist lineages exhibit these structures: Telonemia, Alveolata and Glaucophyta.

Tunicaraptor is a genus of marine microbial protists containing the single species Tunicaraptor unikontum, discovered in 2020 from marine waters of Chile. It is a lineage of predatorial flagellates closely related to animals. It has a rare feeding structure not seen in other opisthokonts.

<i>Syssomonas</i> Genus of protists

Syssomonas is a monotypic genus of unicellular flagellated protists containing the species Syssomonas multiformis. It is a member of Pluriformea inside the lineage of Holozoa, a clade containing animals and their closest protistan relatives. It lives in freshwater habitats. It has a complex life cycle that includes unicellular amoeboid and flagellated phases, as well as multicellular aggregates, depending on the growth medium and nutritional state.

<span class="mw-page-title-main">Colponemid</span> Group of predatorial flagellates

Colponemids are free-living alveolates, unicellular flagellates related to dinoflagellates, apicomplexans and ciliates. They are predators of other small eukaryotes, found in freshwater, marine and soil environments. They do not form a solid clade, but a sparse group of deep-branching alveolate lineages.

<span class="mw-page-title-main">Chrompodellid</span> Clade of alveolates

Chrompodellids are a clade of single-celled protists belonging to the Alveolata supergroup. It comprises two different polyphyletic groups of flagellates: the colpodellids, phagotrophic predators, and the chromerids, photosynthetic algae that live as symbionts of corals. These groups were independently discovered and described, but molecular phylogenetic analyses demonstrated that they are intermingled in a clade that is the closest relative to Apicomplexa, and they became collectively known as chrompodellids. Due to the history of their research, they are variously known in biological classification as Chromerida or Colpodellida (ICZN)/Colpodellales (ICN).

References

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