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Euglenozoa are a large group of flagellate Discoba. They include a variety of common free-living species, as well as a few important parasites, some of which infect humans. Euglenozoa are represented by three major clades, i.e., Kinetoplastea, Diplonema and Symbiontida. Euglenozoa are unicellular, mostly around 15–40 μm (0.00059–0.00157 in) in size, although some euglenids get up to 500 μm (0.020 in) long.
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, the term "flagellate" is included in other terms which are more formally characterized.
Euglena is a genus of single cell flagellate eukaryotes. It is the best known and most widely studied member of the class Euglenoidea, a diverse group containing some 54 genera and at least 200 species. Species of Euglena are found in fresh water and salt water. They are often abundant in quiet inland waters where they may bloom in numbers sufficient to color the surface of ponds and ditches green (E. viridis) or red (E. sanguinea).
Euglenids are one of the best-known groups of flagellates, which are excavate eukaryotes of the phylum Euglenophyta and their cell structure is typical of that group. They are commonly found in freshwater, especially when it is rich in organic materials, with a few marine and endosymbiotic members. Many euglenids feed by phagocytosis, or strictly by diffusion. A monophyletic group consisting of the mixotrophic Rapaza viridis and the two groups Eutreptiales and Euglenales have chloroplasts and produce their own food through photosynthesis. This group is known to contain the carbohydrate paramylon.
Trachelomonas is a genus of swimming, free-living euglenoids characterized by the presence of a shell-like covering called a lorica. Details of lorica structure determine the classification of distinct species in the genus. The lorica can exist in spherical, elliptical, cylindrical, and pyriform (pear-shaped) forms. The lorica surface can be smooth, punctuate or striate and range from hyaline, to yellow, or brown. These colors are due to the accumulation of ferric hydroxide and manganic oxide deposited with the mucilage and minerals that comprise the lorica. In Trachelomonas, the presence of a lorica obscures cytoplasmic details of the underlying cell. In each Trachelomonas cell, there is a gap at the apex of the lorica from which the flagellum protrudes. Thickening around this gap results in a rim-like or collar-like appearance. During asexual reproduction, the nucleus divides yielding two daughter cells one of which exits through the opening in the lorica. This new cell then synthesizes its own new lorica.
The raphidophytes, formally known as Raphidomonadea or Raphidophyceae, are a small group of eukaryotic algae that includes both marine and freshwater species. All raphidophytes are unicellular, with large cells, but no cell walls. Raphidophytes possess a pair of flagella, organised such that both originate from the same invagination. One flagellum points forwards, and is covered in hair-like mastigonemes, while the other points backwards across the cell surface, lying within a ventral groove. Raphidophytes contain numerous ellipsoid chloroplasts, which contain chlorophylls a, c1 and c2. They also make use of accessory pigments including β-carotene and diadinoxanthin. Unlike other heterokontophytes, raphidophytes do not possess the photoreceptive organelle typical of this group.
Trimastix is a genus of excavates, the sole occupant of the order Trimastigida. Trimastix are bacterivorous, free living and anaerobic. When first observed in 1881 by William Kent, the morphology of Trimastix was not well described but over time the oral structure and flagellar organization have become clearer. There are few known species, and the genus's role in the ecosystem is largely unknown. However, it is known that they generally live in marine environments within the tissues of decaying organisms to maintain an anoxic environment. Much interest in this group is related to its close association with other members of Anaeromonadea. These organisms do not have classical mitochondria, and as such, much of the research involving these microbes is aimed at investigating the evolution of mitochondria.
Thaumatomonadida is an order of flagellates.
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.
Ancyromonadida or Planomonadida is a small group of biflagellated protists found in the soil and in aquatic habitats, where they feed on bacteria. Includes freshwater or marine organisms, benthic, dorsoventrally compressed and with two unequal flagellae, each emerging from a separate pocket. The apical anterior flagellum can be very thin or end in the cell membrane, while the posterior flagellum is long and is inserted ventrally or laterally. The cell membrane is supported by a thin single layer teak and the mitochondrial crests are discoidal / flat.
Phacus is a genus of unicellular excavates, of the phylum Euglenozoa, characterized by its flat, leaf-shaped structure, and rigid cytoskeleton known as a pellicle. These eukaryotes are mostly green in colour, and have a single flagellum that extends the length of their body. They are morphologically very flat, rigid, leaf-shaped, and contain many small discoid chloroplasts.
Peranema is a genus of free-living phagotrophic euglenids. There are more than 20 nominal species, varying in size between 8 and 200 micrometers. Peranema cells are gliding flagellates found in freshwater lakes, ponds and ditches, and are often abundant at the bottom of stagnant pools rich in decaying organic material. Although they belong to the class Euglenoidea, and are morphologically similar to the green Euglena, Peranema have no chloroplasts, and do not conduct autotrophy. Instead, they capture live prey, such as yeast, bacteria and other flagellates, consuming them with the help of a rigid feeding apparatus called a "rod-organ." Unlike the green euglenids, they lack both an eyespot (stigma), and the paraflagellar body (photoreceptor) that is normally coupled with that organelle. However, while Peranema lack a localized photoreceptor, they do possess the light-sensitive protein rhodopsin, and respond to changes in light with a characteristic "curling behaviour."
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.
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.
Heteronema is a genus of phagotrophic, flagellated euglenoids that are most widely distributed in fresh water environments. This genus consists of two very distinguishable morphogroups that are phylogenetically closely related. These morphogroups are deciphered based on shape, locomotion and other ultrastructural traits. However, this genus does impose taxonomic problems due to the varying historical descriptions of Heteronema species and its similarity to the genus Paranema. The species H. exaratum, was the first heteronemid with a skidding motion to be sequenced, which led to the discovery that it was not closely related to H. scaphrum, contrary to what was previously assumed, but instead to a sister group of primary osmotrophs. This suggests that skidding heteronemids can also be distinguished phylogenetically, being more closely related to Anisoma, Dinema and Aphageae, than to other species within Heteronema.
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. 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. Colponema is a predator that feeds on smaller flagellates using its ventral groove. Like many other alveolates, they possess trichocysts, tubular mitochondrial cristae, and alveoli. It has been recently proposed that Colponema may be the sister group to all other alveolates. The genus could help us understand the origin of alveolates and shed light on features that are ancestral to all eukaryotes.
Cryptoglena(/ˌkɹɪptoʊˈgliːnə/) is a genus of photosynthetic euglenids that was first described in 1831 by Christian Gottfried Ehrenberg. Today, its circumscription is controversial: Bicudo and Menezes consider twenty-one species as Cryptoglena, of which, nine are uncertain. Cryptoglena species are water-based, living in both freshwater and marine environments. They are biflagellated, with one internal flagellum and one external flagellum, which allows movement through environments as demonstrated by Kim and Shin in the species C. pigra. The cells of Cryptoglena resemble a coffee bean, as they have a groove that runs the length of the cell on one side and makes them U-shaped in cross section. They are ovoid in shape and are small, with the larger cells being on average 25 x 15 μm. After being first described in 1831, little work was done on the genus until the late 1970s and early 1980s, after the scanning electron microscope completed development and was implemented into laboratories. Work then proceeded with the developments of molecular biology, which allows for classifications based on DNA sequences. For Cryptoglena the main DNA used for classification are small subunit (SSU) and large subunit (LSU) rDNA.
Stygiella /ˌstɪ.d͡ʒiˈɛ.lə/ is a genus of free-living marine flagellates belonging to the family Stygiellidae in the jakobids (excavata).
Ochromonas is a genus of algae belonging to the family Chromulinaceae.
Postgaardia is a proposed basal clade of flagellate Euglenozoa, following Cavalier-Smith. As Euglenozoans may be basal Eukaryotes, the Postgaardia may be key to studying the evolution of Eukaryotes, including the incorporation of eukaryotic traits such as the incorporation of alphaproteobacterial mitochondrial endosymbionts.
References
- 1 2 3 4 5 6 7 8 Guiry, M. D.; Guiry, G. M. (2002). “Petalomonas F.Stein 1859”. Retrieved February 10, 2019, from
- 1 2 Lax, G.; Simpson, A. G. (2013). “Combining Molecular Data with Classical Morphology for Uncultured Phagotrophic Euglenids (Excavata): A Single-Cell Approach”. Journal of Eukaryotic Microbiology. 60 (6): 615-625. doi:10.1111/jeu.12068
- ↑ Stein, F. (1859). Der Organismus der Infusionsthiere nach eigenen Forschungen in systematischer Reihenfolge bearb. von Friedrich Stein. doi:10.5962/bhl.title.3933
- 1 2 3 4 5 6 7 8 9 Shawhan, F. M.; Jahn, T. L. (1947). “A Survey of the Genus Petalomonas Stein (Protozoa: Euglenida)”. Transactions of the American Microscopical Society. 66 (2): 182. doi:10.2307/3223249
- 1 2 3 Cavalier-Smith, Thomas; Chao, Ema E.; Vickerman, Keith (2016). “New phagotrophic euglenoid species (new genus Decastava; Scytomonas saepesedens; Entosiphon oblongum), Hsp90 introns, and putative euglenoid Hsp90 pre-mRNA insertional editing”. European Journal of Protistology. 56: 147-170. doi:10.1016/j.ejop.2016.08.002
- 1 2 Esson, H. J.; Leander, B. S. (2006). “A model for the morphogenesis of strip reduction patterns in phototrophic euglenids: Evidence for heterochrony in pellicle evolution”. Evolution Development, 8 (4): 378-388. doi:10.1111/j.1525-142x.2006.00110.x
- 1 2 3 4 Larsen, Jacob; Patterson, David J. (1990). "Some flagellates (Protista) from tropical marine sediments”. Journal of Natural History, 24 (4): 801-937. doi:10.1080/00222939000770571
- ↑ Breglia, Susana A.; Yubuki, N.; Leander, Brian S. (2013). “Ultrastructure and Molecular Phylogenetic Position of Heteronema scaphurum: A Eukaryovorous Euglenid with a Cytoproct”. Journal of Eukaryotic Microbiology. 2: 107-120. doi: 10.1111/jeu.12014