Rhynchopus

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Rhynchopus
Scientific classification
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Genus:
Rhynchopus

Skuja 1948
Type species
Rhynchopus amitus
Skuja 1948
Species
  • R. amitusSkuja 1948
  • R. coscinodiscivorusSchnepf 1994
  • R. euleeidesRoy et al. 2007
  • R. humrisTashyreva et al. 2018
  • R. littoralensisKufferath 1950
  • R. serpensTashyreva et al. 2018

Rhynchopus is a genus of flagellate excavates in the class Diplonemea. They usually have flagella of different lengths and a single subapical opening with the flagellar pocket openings and adjacent feeding apparatus merging into one. When food is scarce, mobile flagellated cells are produced, suggesting the presence of a fully flagellated and dispersive phase in the life cycle, serving to distinguish Rhynchopus from Diplonema. Most species are free-living, others are symbionts and R. coscinodiscivorus is an intracellular parasite of diatoms.

Species

The type species, R. amitus, has been described in Baltic plankton. It has an elongated pear shaped body, often more concave on one side than the other. A disc separates the flagellar apparatus ingestion pocket and two flagella pocket as they emerge from the cell. They have been found feeding on planktonic diatoms cytoplasm and gills of crayfish and crabs. In addition to the mobile phase flagellate stages also produces a cyst.

R. euleeides is a free-living marine flagellate. In the trophic stage, the cells are predominantly elliptical and flattened laterally, but often change their shape . Slippage is the predominant form of locomotion. The two flagella, which are normally hidden in the sub-apical pocket, are short and of unequal length and have conventional axonemes, but seems to lack the paraxonemales rods. Swimmer cells, which are only occasionally seen, are smaller and have two conspicuous flagella, more than twice the length of the body. [1] [2]

Related Research Articles

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A flagellate is a cell or organism with one or more whip-like appendages called flagella. The word flagellate also describes a particular construction characteristic of many prokaryotes and eukaryotes and their means of motion. The term presently does not imply any specific relationship or classification of the organisms that possess flagella. However, several derivations of the term "flagellate" are more formally characterized.

<span class="mw-page-title-main">Flagellum</span> Cellular appendage functioning as locomotive or sensory organelle

A flagellum is a hairlike 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 protists with flagella are known as flagellates.

<i>Naegleria</i> Genus of protists

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.

<i>Stephanopogon</i> Genus of flagellate marine protozoan

Stephanopogon is a genus of flagellated marine protist that superficially resembles a ciliate.

<i>Tetraselmis</i> Genus of algae

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.

<i>Bodo</i> (excavate) Genus of micro-organisms

Bodo is a genus of microscopic kinetoplastids, flagellate excavates first described in 1831 by Christian Gottfried Ehrenberg. The genus is small, as it has recently been redefined to include only four species. Bodo includes free-living, phagotrophic organisms that can be found in many marine and freshwater environments as well as some terrestrial environments. Being phagotrophic, Bodo feeds on bacteria and other microorganisms that it finds while swimming through its water-based habitats. The swimming-like movement is facilitated by the two unequal flagella that Bodo possesses which arise from an anteriorly located flagellar pocket. Bodo is roughly bean-shaped and is often missed in samples from water or terrestrial environments due to its small size.

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

Oxyrrhis is a genus of heterotrophic dinoflagellate, the only genus in the family Oxyrrhinaceae. It inhabits a range of marine environments worldwide and is important in the food web dynamics of these ecosystems. It has the potential to be considered a model organism for the study of other protists. Oxyrrhis is an early-branching lineage and has long been described in literature as a monospecific genus, containing only Oxyrrhis marina. Some recent molecular phylogenetic studies argue that Oxyrrhis comprises O. marina and O. maritima as distinct species, while other publications state that the two are genetically diverse lineages of the same species. The genus has previously been suggested to contain O. parasitica as a separate species, however the current consensus appears to exclude this, with Oxyrrhis being monospecific and containing O. marina and O. maritima as separate lineages of the type species. The genus is characterised by its elongated body which is anteriorly prolonged to a point, its complex flagellar apparatuses which attach to the ventral side of the cell, and the unique features of its nucleus.

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

Thaumatomastix is a protist genus of the order Thaumatomonadida, within the phylum Cercozoa and the class Imbricatea. Its species are aquatic, feeding on algae and appearing in waters of a wide range of temperatures and salinities, and are 15-50 micrometers long. They can interchange between flagellated and amoeboid forms, and are notable for being covered in both spiny and flattened siliceous scales.

<i>Oxyrrhis marina</i> Species of single-celled organism

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Diplonemidae is a family of biflagellated unicellular protists that may be among the more diverse and common groups of planktonic organisms in the ocean. Although this family is currently made up of three named genera; Diplonema, Rhynchopus, and Hemistasia, there likely exist thousands of still unnamed genera. Organisms are generally colourless and oblong in shape, with two flagella emerging from a subapical pocket. They possess a large mitochondrial genome composed of fragmented linear DNA. These non-coding sequences must be massively trans-spliced, making it one of the most complicated post-transcriptional editing process known to eukaryotes.

<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.

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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">Protist locomotion</span> Motion system of a type of eukaryotic organism

Protists are the eukaryotes that cannot be classified as plants, fungi or animals. They are mostly unicellular and microscopic. Many unicellular protists, particularly protozoans, are motile and can generate movement using flagella, cilia or pseudopods. Cells which use flagella for movement are usually referred to as flagellates, cells which use cilia are usually referred to as ciliates, and cells which use pseudopods are usually referred to as amoeba or amoeboids. Other protists are not motile, and consequently have no built-in movement mechanism.

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.

References

  1. Roy, J. Faktotova, D. Benada, O. Lukes, J. Burger, G., Description of Rhynchopus euleeides n. sp. (Diplonemea), a Free-Living Marine Euglenozoan [ permanent dead link ], Journal of Eukaryotic Microbiology, Volume 54, Number 2, March–April 2007 , pp. 137-145(9).
  2. Brands, S.J. (comp.) 1989-2007. The Taxonomicon. Universal Taxonomic Services, Amsterdam, the Netherlands. , Fecha de acceso: 7 de Febrero del 2016.