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The parabasalids are a group of flagellated protists within the supergroup Excavata. Most of these eukaryotic organisms form a symbiotic relationship in animals. These include a variety of forms found in the intestines of termites and cockroaches, many of which have symbiotic bacteria that help them digest cellulose in woody plants. Other species within this supergroup are known parasites, and include human pathogens.
Naegleria is a genus consisting of 47 described species of protozoa often found in warm aquatic environments as well as soil habitats worldwide. It has three life cycle forms: the amoeboid stage, the cyst stage, and the flagellated stage, and has been routinely studied for its ease in change from amoeboid to flagellated stages. The Naegleria genera became famous when Naegleria fowleri, the causative agent of the usually fatal human and animal disease primary amoebic meningoencephalitis (PAM), was discovered in 1965. Most species in the genus, however, are incapable of causing disease.
Tetraselmis is a genus of phytoplankton. Tetraselmis is a green algal genus within the order Chlorodendrales, and they are characterized by their intensely-colored green chloroplast, their flagellated cell bodies, the presence of a pyrenoid within the chloroplast, and a scale-produced thecal-wall. Species within this genus are found in both marine and freshwater ecosystems across the globe; their habitat range is mainly limited by water depth due to their photosynthetic nature. Thus, they live in diverse water environments if enough nutrients and light are available for net photosynthetic activity. Tetraselmis species have proven to be useful for both research and industry. Tetraselmis species have been studied for understanding plankton growth rates, and recently a colonial species is being used to gain an understanding of multicellularity evolution. Additionally, many species are currently being examined for their use as biofuels due to their high lipid content.
Trichonympha is a genus of single-celled, anaerobic parabasalids of the order Hypermastigia that is found exclusively in the hindgut of lower termites and wood roaches. Trichonympha’s bell shape and thousands of flagella make it an easily recognizable cell. The symbiosis between lower termites/wood roaches and Trichonympha is highly beneficial to both parties: Trichonympha helps its host digest cellulose and in return receives a constant supply of food and shelter. Trichonympha also has a variety of bacterial symbionts that are involved in sugar metabolism and nitrogen fixation.
Auranticordis is a genus of rare tetraflagellate eukaryotic organisms within the phylum Cercozoa. Currently there is only one characterized species within this genus: Auranticordis quadriverberis.Auranticordis cells are heart shaped and can range from 35 - 75 μm long and 25 - 70 μm wide. These cells move in a forward gliding motion, and are predators in interstitial marine sand habitats. Auranticordis cells contain several features that are unique and dissimilar from other cercozoans, such as black bodies, reduced acristate mitochondria, putative primary endosymbionts, many orange pigmented extrusomes and the absence of permanently condensed chromosomes.
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.
Proteromonas is a genus of single-celled biflagellated microbial eukaryotes belonging to the Superphylum Stramenopiles which are characterized by the presence of tripartite, hair-like structures on the anteriorly-directed larger of the two flagella. Proteromonas on the other hand are notable by having tripartite hairs called somatonemes not on the flagella but on the posterior of the cell. Proteromonas are closely related to Karotomorpha and Blastocystis, which belong to the Opalines group.
Mastigamoeba is a genus of pelobionts, and treated by some as members of the Archamoebae group of protists. Mastigamoeba are characterized as anaerobic, amitochondriate organisms that are polymorphic. Their dominant life cycle stage is as an amoeboid flagellate. Species are typically free living, though endobiotic species have been described.
Psalteriomonas is a genus of excavates in the group of Heterolobosea. The genus was first discovered and named in 1990. It contains amoeboflagellate cells that live in freshwater anaerobic sediments all over the world. The microtubule-organizing ribbon and the associated microfibrillar bundles of the mastigote system is the predominant feature in Psalteriomonas. This harp-shaped complex gives rise to the name of this genus. Psalteriomonasforms an endosymbiotic relationship with methanogenic bacteria, especially with Methanobacterium formicicum There are currently three species in this genus: P. lanterna, P. vulgaris, and P. magna.
Willaertia /ˈwɪləɹʃə/ is a genus of non-pathogenic, free-living, thermophilic amoebae in the family Vahlkampfiidae.
Monocercomonoides is a genus of flagellate Excavata belonging to the order Oxymonadida. It was established by Bernard V. Travis and was first described as those with "polymastiginid flagellates having three anterior flagella and a trailing one originating at a single basal granule located in front of the anteriorly positioned nucleus, and a more or less well-defined axostyle". It is the first eukaryotic genus to be found to completely lack mitochondria, and all hallmark proteins responsible for mitochondrial function. The genus also lacks any other mitochondria related organelles (MROs) such as hydrogenosomes or mitosomes. Data suggests that the absence of mitochondria is not an ancestral feature, but rather due to secondary loss. Monocercomonoides sp. was found to obtain energy through an enzymatic action of nutrients absorbed from the environment. The genus has replaced the iron-sulfur cluster assembly pathway with a cytosolic sulfur mobilization system, likely acquired by horizontal gene transfer from a eubacterium of a common ancestor of oxymonads. These organisms are significant because they undermine assumptions that eukaryotes must have mitochondria to properly function. The genome of Monocercomonoides exilis has approximately 82 million base pairs, with 18 152 predicted protein-coding genes.
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.
Stygiella /ˌstɪ.d͡ʒiˈɛ.lə/ is a genus of free-living marine flagellates belonging to the family Stygiellidae in the jakobids (excavata).
Saccinobaculus is a genus of unicellular eukaryotes that resides in the hindgut of the wood-feeding cockroach Cryptocercus punctulatus. This genus is known for its distinctive movement that resembles a snake trashing in a bag. The genus is involved in the digestion of wood materials within its insect-host and is vertically transmitted to insect progeny. The genus is the part of the family Saccinobaculidae.
Holomastigotoides is a genus of parabasalids found in the hindgut of lower termites. It is characterized by its dense, organized arrangement of flagella on the cell surface and the presence of a mitotic spindle outside its nucleus during the majority of its cell cycle. As a symbiont of termites, Holomastigotoides is able to ingest wood and aid its host in digestion. In return, Holomastigotoides is supplied with a stable habitat and steady supply of food. Holomastigotoides has notably been studied to observe the mechanisms of chromosomal pairing and segregation in haploid and diploid cells.
Monocercomonas is a Parabasalian genus belonging to the order Trichomonadida. It presents four flagella, three forward-facing and one trailing, without the presence of a costa or any kind of undulating membrane. Monocercomonas is found in animal guts. and is susceptible to cause Monocercomoniasis in reptiles
Viridiraptoridae, previously known as clade X, is a clade of heterotrophic protists in the phylum Cercozoa. They're a family of glissomonads, a group containing a vast, mostly undescribed diversity of soil and freshwater organisms.
Cafileria is a genus of marine microscopic protists. It is monotypic, comprising the single species Cafileria marina, described in 2019 from Norway. It is part of a clade of heterotrophic flagellates that consume bacteria, known as Bicosoecida, a basal lineage of Stramenopiles. Due to its small size it is described as a nanoflagellate. It is the only organism where direct connections between mitochondria and the cell nucleus have been observed. Another peculiarity of C. marina is the change in shape of the Golgi apparatus during the cell cycle.
Multicilia marina is a flagellated, multiciliated amoeboid protist found in brackish water. It can take on many different morphological characteristics, some dependent on its environment, such as different quantities and orientations of flagella. Leon Cienkowski is credited with the first discovery of a species of this organism.
References
- ↑ Ayala, F. J.; Fitch, W. M.; Clegg, M. T. (2000). "Variation and evolution in plants and microorganisms: Towards a new synthesis 50 years after Stebbins". Proceedings of the National Academy of Sciences of the United States of America. 97 (3): 6941–4. Bibcode:2000PNAS...97.6941A. doi: 10.1073/pnas.97.13.6941 . PMC 34366 . PMID 10860953.
- 1 2 Brugerolle, Guy; König, Helmut (2007). "Ultrastructure and Organization of the Cytoskeleton in Oxymonas, an Intestinal Flagellate of Termites". The Journal of Eukaryotic Microbiology. 44 (4): 305–313. doi:10.1111/j.1550-7408.1997.tb05671.x. S2CID 85868269.
- 1 2 Rother, A.; Radek, R.; Hausmann, K. (1999). "Characterization of surface structures covering termite flagellates of the family Oxymonadidae and ultrustructure of two Oxymonda species, Microhapolodina multinucleate and Oxymonsa sp". European Journal of Protistology. 35 (1). doi:10.1016/S0932-4739(99)80018-2.
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