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Heterokont
The stramenopiles, also called heterokonts, are protists distinguished by the presence of stiff tripartite external hairs. In most species, the hairs are attached to flagella, in some they are attached to other areas of the cellular surface, and in some they have been secondarily lost (in which case relatedness to stramenopile ancestors is evident from other shared cytological features or from genetic similarity). Stramenopiles represent one of the three major clades in the SAR supergroup, along with Alveolata and Rhizaria. Stramenopiles are eukaryotes; most are single-celled, but some are multicellular including some large seaweeds, the brown algae. The group includes a variety of algal protists, heterotrophic flagellates, opalines and closely related proteromonad flagellates (all endobionts in other organisms); the actinophryid Heliozoa, and oomycetes. The tripartite hairs characteristic of the group have been lost in some of the included taxa – for example in most ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ochrophyte
Ochrophytes, also known as heterokontophytes or stramenochromes, are a phylum of algae. They are the photosynthetic stramenopiles, a group of eukaryotes, organisms with a cell nucleus, characterized by the presence of two unequal flagella, one of which has tripartite hairs called mastigonemes. In particular, they are characterized by photosynthetic organelles or plastids enclosed by four membranes, with membrane-bound compartments called thylakoids organized in piles of three, chlorophyll ''a'' and ''c'' as their photosynthetic pigments, and additional pigments such as β-carotene and xanthophylls. Ochrophytes are one of the most diverse lineages of eukaryotes, containing ecologically important algae such as brown algae and diatoms. They are classified either as phylum Ochrophyta, Heterokontophyta or as subphylum Ochrophytina withing phylum Gyrista. Their plastids are of red algal origin. Description Ochrophytes are eukaryotic organisms composed of cells that are eithe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Yellow-green Algae
Yellow-green algae or the Xanthophyceae (xanthophytes) are an important group of heterokont algae. Most live in fresh water, but some are found in marine and soil habitats. They vary from single-celled flagellates to simple colonial and filamentous forms. Xanthophyte chloroplasts contain the photosynthetic pigments chlorophyll ''a'', chlorophyll ''c'', β-carotene, and the carotenoid diadinoxanthin. Unlike other Stramenopiles (heterokonts), their chloroplasts do not contain fucoxanthin, which accounts for their lighter colour. Their storage polysaccharide is chrysolaminarin. Xanthophyte cell walls are produced of cellulose and hemicellulose. They appear to be the closest relatives of the brown algae. Classifications The species now placed in the Xanthophyceae were formerly included in the Chlorophyceae. In 1899, Lüther created the group Heterokontae for green algae with unequal flagella. Pascher (1914) included the Heterokontae in the Chrysophyta. In 1930, Allorge renamed t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gyrista
Gyrista is a clade of stramenopile protists containing three diverse groups: the mostly photosynthetic Ochrophyta, the parasitic Pseudofungi, and the recently described group of nanoflagellates known as Bigyromonada. Members of this phylum are characterized by the presence of a helix or a double helix/ring system in the ciliary transition region. Systematics Taxonomic history Gyrista was first described in 1998 by protistologist Thomas Cavalier-Smith in his work ''A revised six-kingdom system of life'', originally as a superphylum containing two phyla: Ochrophyta, the heterokont algae; and Bigyra, which then contained the pseudofungi and bigyromonads together with the opalines. Later, the name Bigyra was modified to contain opalines, bicosoecids and labyrinthulomycetes, while the Ochrophyta, Pseudofungi and Bigyromonada remained as groups within Gyrista. Molecular phylogenetics Gyrista was seen in 2017 as the sister group to phylum Bigyra, which contains the Sag ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bigyra
Bigyra () is a phylum of microscopic eukaryotes that are found at the base of the Stramenopiles clade. It includes three well-known heterotrophic groups Bicosoecida, Opalinata and Labyrinthulomycetes, as well as several small clades initially discovered through environmental DNA samples: Nanomonadea, Placididea, Opalomonadea and Eogyrea. The classification of Bigyra has changed several times since its origin, and its monophyly remains unresolved. Ecological diversity Bigyra is a diverse group of heterotrophic, mainly phagotrophic stramenopiles that lack cell walls. It contains three well-known important groups with widely different ecological functions and morphologies: labyrinthulomycetes, opalines and bicosoecids. Labyrinthulomycetes is a group of protists that absorb nutrients in an osmotrophic or phagotrophic manner. They can behave either as free-living amoebae or as mycelium-like networks of cytoplasmic threads. Some of them are saprotrophic decomposers of the detritus, de ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pseudofungi
Pseudofungi is a grouping of heterokonts, also known as the Heterokontimycotina. It consists of the Oomycetes and Hyphochytriomycetes. Although numerous biochemical, ultrastructural, and genetic traits clearly place them in the heterokonts, their growth form (featuring hyphae) and mode of nutrition ( osmotrophy) resemble that of fungi (which are not closely related). Origin and ancestors It is believed that pseudofungi descend from unicellular algae among the Stramenopiles which lost their plastids. While evidence of these plastids hasn't been found, what has been proven is the existence of endosymbiotic red algae plastids. From this, a unicellular heterotroph proto-pseudofungi (probably a mushroom parasite) got its fungal genes through horizontal gene transfer, which would have led to the development of convergent fungal multicellularity, explaining why the cell wall is sometimes made of both chitin and cellulose Cellulose is an organic compound with the chemical form ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oomycete
The Oomycetes (), or Oomycota, form a distinct phylogenetic lineage of fungus-like eukaryotic microorganisms within the Stramenopiles. They are filamentous and heterotrophic, and can reproduce both sexually and asexually. Sexual reproduction of an oospore is the result of contact between hyphae of male antheridia and female oogonia; these spores can overwinter and are known as resting spores. Asexual reproduction involves the formation of chlamydospores and sporangia, producing motile zoospores. Oomycetes occupy both saprophytic and pathogenic lifestyles, and include some of the most notorious pathogens of plants, causing devastating diseases such as late blight of potato and sudden oak death. One oomycete, the mycoparasite '' Pythium oligandrum'', is used for biocontrol, attacking plant pathogenic fungi. The oomycetes are also often referred to as water molds (or water moulds), although the water-preferring nature which led to that name is not true of most species, whi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bicosoecid
Bicosoecida ( ICZN) or Bicosoecales/Bicoecea ( ICBN) is an order of Bikosea, a small group of unicellular flagellates, included among the stramenopiles. Informally known as bicosoecids, they are free-living cells, with no chloroplasts, and in some genera are encased in a lorica. The name of the type genus '' Bicosoeca'' described by James-Clark in 1866 is derived from Greek roots (, vase, bowl, plus ''oekein'', inhabit). The philologically preferable compound would be ''Bicoeca'', as "corrected" by Stein in 1878 and followed by most subsequent authors. However, according to the ICBN and ICZN, the original spelling of the name cannot be considered incorrect and it must be used in its original form. The group was formerly considered to be related to the Chrysophyceae. Some authors use the vernacular term "bicosoecid" (or "bicoecid") in a narrower sense, only for ''Bicosoeca'', applying "bicoeceans" to ''Bicosoeca'' and related groups like '' Cafeteria''. With the advent of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Flagella
A flagellum (; : flagella) (Latin for 'whip' or 'scourge') is a hair-like 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. A microorganism may have from one to many flagella. A gram-negative bacterium '' Helicobacter pylori'', for example, uses its flagella to propel itself through the stomach to reach the mucous lining where it may colonise the epithelium and potentially cause gastritis, and ulcers – a risk factor for stomach cancer. In some swarming bacteria, the flagellum can also function as a sensory organelle, being sensitive to wetness outside the cell. Across the three domains of Bacteria, Archaea, and Eukaryota, the flagellum has a different structure, protein composition, and mechanism of propulsion but shares the same function of providing motility. The Latin word means " whip" to describe its ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bigyromonada
Bigyromonada is a recently described non-photosynthetic lineage of stramenopiles that at present contains two classes. Description Bigyromonads are characterized by biciliate cells that feed on bacteria through phagotrophy. They are marine organisms. Taxonomy * Clade Bigyromonada Cavalier-Smith 1998 ** Class Developea Karpov & Aleoshin 2016 ex Cavalier-Smith 2017 *** Order Developayellales Doweld 2001 evelopayellida Cavalier-Smith 1987**** Family Developayellaceae Cavalier-Smith 1997 evelopayellidae***** '' Developayella'' Tong 1995 ****** '' Developayella elegans'' Tong 1995 ***** '' Develorapax'' Karpov & Aleoshin 2016 ****** '' Develorapax marinus'' Karpov & Aleoshin 2016 ** Class Pirsonea *** Order Pirsoniales ''Pirsonia'' is a non photosynthetic genus of heterokont The stramenopiles, also called heterokonts, are protists distinguished by the presence of stiff tripartite external hairs. In most species, the hairs are attached to flagella, in some t ... Cava ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alveolate
The alveolates (meaning "pitted like a honeycomb") are a group of protists, considered a major unranked clade or superphylum within Eukaryota. They are currently grouped with the Stramenopiles and Rhizaria among the protists with tubulocristate mitochondria into the SAR supergroup. Characteristics The most notable shared characteristic is the presence of cortical (near the surface) alveoli (sacs). These are flattened vesicles (sacs) arranged as a layer just under the membrane and supporting it, typically contributing to a flexible pellicle (thin skin). In armored dinoflagellates they may contain stiff plates. Alveolates have mitochondria with tubular cristae ( invaginations), and cells often have pore-like intrusions through the cell surface. The group contains free-living and parasitic organisms, predatory flagellates, and photosynthetic organisms. Almost all sequenced mitochondrial genomes of ciliates and apicomplexa are linear. The mitochondria almost all carry mtDN ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Protist
A protist ( ) or protoctist is any eukaryotic organism that is not an animal, land plant, or fungus. Protists do not form a natural group, or clade, but are a paraphyletic grouping of all descendants of the last eukaryotic common ancestor excluding land plants, animals, and fungi. Protists were historically regarded as a separate taxonomic kingdom known as Protista or Protoctista. With the advent of phylogenetic analysis and electron microscopy studies, the use of Protista as a formal taxon was gradually abandoned. In modern classifications, protists are spread across several eukaryotic clades called supergroups, such as Archaeplastida ( photoautotrophs that includes land plants), SAR, Obazoa (which includes fungi and animals), Amoebozoa and " Excavata". Protists represent an extremely large genetic and ecological diversity in all environments, including extreme habitats. Their diversity, larger than for all other eukaryotes, has only been discovered in rece ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
