| Monocercomonas | |
|---|---|
Scientific classification  | |
| Domain: | Eukaryota |
| Phylum: | Metamonada |
| Order: | Trichomonadida |
| Family: | Monocercomonadidae |
| Genus: | Monocercomonas Grassi, 1879 |
Monocercomonas is a Parabasalian genus belonging to the order Trichomonadida. [1] [2] 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. [3] and is susceptible to cause Monocercomoniasis in reptiles [4]
Mono: single, [5] kerko: tail (one trailing flagella) monas from monad. [6]
The first description of this genus was made by Grassi in 1979. Monocercomonas sp. was initially found in snake guts. The taxa was independently discovered by Kofois and Swezy in 1915, and named Eutrichomastix. Monocercomonas is discovered in beetle guts in 1966, [3] and later found in other invertebrate species.
Monocercomonas has been identified in Japan, Southern California and South Africa, [1] as well as in the Pacific Ocean, west of Chile with a DNA sample from the Tara Ocean mission. [7]
Monocercomonas is a symbiote living in animal guts : it is present in the intestine of several reptiles and birds, [8] as well as the hindgut of the wood-eating cockroach Parasphaeria boleiriana . [3] It was also found in domestic birds such as the Chicken (Gallus gallus) and Ducks (Anas sp.). [9] Monocercomonas is an anaerobic organism that doesn't digest wood despite being found in wood-eating organisms ; it is possibly a parasite for snakes, as it was found in abundance in sick snakes guts as well as other organs (lungs and oviducts) and was associated with mortality of the snakes. However it was also found in healthy animals. Monocercomonas needs a nutrient-rich substrate to subsist, and lives in anaerobic environments. [10]
Monocercomonas are single celled flagellated eucaryotes. The most commonly occurring form of the cell is a trophozoite. Their body shape is roughly oval, measuring approximately 10 μm in length and 3 μm in width, although some specimen assume a more spherical shape (save for the axostylar trunk). Monocercomonas have four flagella, three pointing forward measuring approximately 17μm, and one trailing behind the organism, the recurrent flagellum, measuring approximately 30μm. Their axostyle, characteristic of Parabasalians protrudes at the opposite of the cell from the flagellar implantation (posterior side). It measures roughly 5μm, is made out of a rolled sheet of microtubules, and forms a trunk where it protrudes, as it is surrounded by the cell membrane.
The axostyle of Monocercomonas sp. is composed of 13 protofilaments of parallel microtubules, associated with a lateral projection of two protofilaments. The axostyle is connected to hydrogenosomes, the pelta, and endoplasmic reticulum. [11]
Contrary to other genera of Trichomonad that present an undulating membreane associated to the trailing flagella [12] ], Monocercomonas does not have an undulating membrane attached to the trailing flagella, although there is a pelta at the anterior end of the organism, close to the periflagellar canal, attaching it partially to the body. [13]
Monocercomonas has four basal bodies (=kinetostomes) corresponding to its four flagella. Three parallel basal bodies are at the origin of the anterior flagella and point towards the anterior side, the fourth is perpendicular to the others and is at the base of the trailing flagella. Two types of inclusion are seen through the cytoplasm. We also observe endoplasmic reticulum near the cell nucleus. [14] All anterior flagella go through the periflagellar canal, the trailing flagellum does not. [15]
Parabasal filaments are observed between the nucleus and a disc-shaped parabasal body (which is the Golgi body), a synapomorphy of Parabasalians
Monocercomonas is an early diverging branch of Trichomonadida, [14] but the loss of pelta and other cytoskeletal structures in this genera is thought to be secondary, meaning that they were present in the Trichomonadida last common ancestor.
There are transitional fibers at the distal end of the kinetostomes, situated close and anteriorally to the parabasal body which displays a common cisternae organization for Golgi bodies. Parabasal filaments emerge from kinetosome complexes, none of them having the functionality of a cell costa, but the most dorsal one displaying a similar organization and positioning inside the cell as a Tritrichomonas (another genus of Trichomonads). [15]
There are numerous glycogen granules (energy storage) around the cell nucleus, called perinuclear granula and inside the axostyle trunk, called endoaxostylary granula.
In the cytoplasm, Monocercomonas presents food vacuoles and hydrogenosomes. [16]
Hydrogenosomes allow Monocercomonas to perform anaerobic respiration as well as other metabolic pathways vital to the cell. According to Diniz et al. (2007):
In Monocercomonas sp. hydrogenosomes are spherical, rod-like or dumb-bell structures whereas in other trichomonads they are spherical or elongated structures (when in division). They present double membrane, which is positive for carbo- hydrates. The hydrogenosomes in Monocercomonas sp. do not follow the axostyle direction as described for other anaerobic protozoa such as T. foetus and T. vagirzulis. [15]
The production of acetate and hydrogen and its possible advantages for the wood-eating, intermediate host has not been studied in Monocercomonas, but Monocercomonas does not present woodchips-filled food vacuoles despite living in wood-eating organisms : as such it is thought to be a parasite rather than a member of a mutually beneficial relationship for the wood-eating organism. [13]
A resistant pseudocyst can occur under adverse conditions, such as pH of 6.0 and under, high temperatures (37 °C) and nutrient depletion. [15] [14]
The pseudocyst forms by internalizing first the flagella, then the axostyle (retracting back into the body); The cell forms as cell wall and is surrounded by glycocalyx. The cytoplasm of the cysts contains the organelles including those that have been retracted and is more granular than in the trophozoite form [17]
Asexual cell division has been described. The cell division is typical of Parabasalians, with kinetosomes becoming anterior/posterior, despite their previous positioning in the mother cell.
Monocercomonas has only been observed undergoing asexual reproduction. As an animal symbiont, it undergoes a direct life-cycle (without intermediary organism) and reaches animals by orofecal contamination, making it difficult to handle in small, enclosed spaces such as terrariums. [18]
Reptiles infected with Monocercomonas may develop monocercomoniasis (a proliferation of Monocercomonas in the gut, eventually causing lesions and disrupting the gut fauna), which causes them to stop eating, lose weight and show digestive discomfort; the disease can be deadly. In some cases there has been colic, gut necrosis and infertile eggs. In terrarium, the disease can be transmitted between snakes within weeks. However Monocercomoniasis does not present in all snakes infected with Monocercomonas. Immune system function, stress exposure and the species of snake (due to host specificity ; garter snakes are to host Monocercomonas without developing symptoms) can increase the risk of a symptomatic infection. Pneumonia in snakes can also be caused by Monocercomonas, and Monocercomonas can spread to the female reproductive system, causing inflammation. [19]
Subgenus : Alimonas (no pelta), Quadrimonas (longer pelta), Monocercomonas (very short pelta). When there is an accessory filament (pelta) present, it is parallel to the trailing flagella but intracellular.
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.
Trichomonas is a genus of anaerobic excavate parasites of vertebrates. It was first discovered by Alfred François Donné in 1836 when he found these parasites in the pus of a patient suffering from vaginitis, an inflammation of the vagina. Donné named the genus from its morphological characteristics. The prefix tricho- originates from the Ancient Greek word θρίξ (thrix) meaning hair, describing Trichomonas’s flagella. The suffix -monas, describes its similarity to unicellular organisms from the genus Monas.
The metamonads are a large group of flagellate amitochondriate microscopic eukaryotes. Their composition is not entirely settled, but they include the retortamonads, diplomonads, and possibly the parabasalids and oxymonads as well. These four groups are all anaerobic, occurring mostly as symbiotes or parasites of animals, as is the case with Giardia lamblia which causes diarrhea in mammals.
Retortamonas is a genus of flagellated excavates. It is one of only two genera belonging to the family Retortamonadidae along with the genus Chilomastix. The genus parasitizes a large range of hosts including humans. Species within this genus are considered harmless commensals which reside in the intestine of their host. The wide host diversity is a useful factor given that species are distinguished based on their host rather than morphology. This is because all species share similar morphology, which would present challenges when trying to make classifications based on structural anatomy. Although Retortamonas currently includes over 25 known species, it is possible that some defined species are synonymous, given that such overlapping species have been discovered in the past. Further efforts into learning about this genus must be done such as cross-transmission testing as well as biochemical and genetic studies. One of the most well-known species within this genus is Retortamonas intestinalis, a human parasite that lives in the large intestine of humans.
Mixotricha paradoxa is a species of protozoan that lives inside the gut of the Australian termite species Mastotermes darwiniensis.
Trichomonadida is an order of anaerobic protists, included with the parabasalids. Members of this order are referred to as trichomonads.
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.
Blastocystis is a genus of single-celled parasites belonging to the Stramenopiles that includes algae, diatoms, and water molds. There are several species, living in the gastrointestinal tracts of species as diverse as humans, farm animals, birds, rodents, reptiles, amphibians, fish, and cockroaches. Blastocystis has low host specificity, and many different species of Blastocystis can infect humans, and by current convention, any of these species would be identified as Blastocystis hominis.
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.
Trichomonas gallinae is a cosmopolitan parasite of birds including finches, pigeons, doves, turkeys, chickens, parrots, raptors. The condition in birds of prey is called frounce. It is believed to be an ancient pathogen causing frounce-like symptoms in theropod dinosaurs. The same condition in pigeons is commonly called canker.
Dientamoeba fragilis is a species of single-celled excavates found in the gastrointestinal tract of some humans, pigs and gorillas. It causes gastrointestinal upset in some people, but not in others. It is an important cause of travellers diarrhoea, chronic diarrhoea, fatigue and, in children, failure to thrive. Despite this, its role as a "commensal, pathobiont, or pathogen" is still debated. D. fragilis is one of the smaller parasites that are able to live in the human intestine. Dientamoeba fragilis cells are able to survive and move in fresh feces but are sensitive to aerobic environments. They dissociate when in contact or placed in saline, tap water or distilled water.
The Mastigont system is a series of structures found in several Protists such as thrichomonads and amoebae. It is formed by the basal bodies and several other structures composed of fibrils. Their function is not fully understood. The system is studied and visualised mainly through techniques such as plasma membrane extraction, high-voltage electron microscopy, field emission scanning electron microscopy, the cell-sandwich technique, freeze-etching, and immunocytochemistry.
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.
Cochlosoma is a genus of flagellated protozoa in the order Trichomonadida created by A. Kotlán (1923). Some of their typical features include a prominent adhesive disc, axostyle, costa, and six flagella – one of which is attached to an undulating membrane that runs laterally along the body.
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.
Bihospites is a genus of symbiontid euglenozoans characterized by the presence of two species of epibiotic bacteria on the cell surface. Bihospites cells are clear, biflagellated, and uninucleated, that range between 40–120 μm long and 15–30 μm wide. Bihospites, as well as other members of the symbiontids, are found in semi-anoxic to anoxic sediments in benthic marine environments. Each cell surface is covered by both rod-shaped and spherical-shaped epibiotic bacteria that may share a commensalistic or mutualistic relationship with Bihospites host cells. Bihospites cells are highly contractile and contain several morphological synapomorphies which are present in euglenozoans, however they also contain several unique morphological traits including a unique C-shaped feeding apparatus.
| Authority control databases: National |
|---|
