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Heterokont
Heterokonts are a group of protists (formally referred to as Heterokonta, Heterokontae or Heterokontophyta). The group is a major line of eukaryotes. Most are algae, ranging from the giant multicellular kelp to the unicellular diatoms, which are a primary component of plankton. Other notable members of the Stramenopiles include the (generally) parasitic oomycetes, including '' Phytophthora'', which caused the Great Famine of Ireland, and '' Pythium'', which causes seed rot and damping off. The name "heterokont" refers to the type of motile life cycle stage, in which the flagellated cells possess two differently arranged flagella (see zoospore). History In 1899, Alexander Luther created the term "Heterokontae" for some algae with unequal flagella, today called Xanthophyceae. Later, some authors (e.g., Copeland, 1956) included other groups in Heterokonta, expanding the name's sense. The term continues to be applied in different ways, leading to Heterokontophyta being appl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Xanthophyceae
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 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 the group ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gyrista
Gyrista is a phylum of heterokont 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. Phylogeny Gyrista is the sister group to phylum Bigyra, which contains the Sagenista and Opalozoa. Together, Gyrista and Bigyra form the superphylum Stramenopiles or Heterokonta. A phylogenetic analysis in 2022 recovered a monophyletic Bigyromonada sister to Pseudofungi: Classification The 2018 revised taxonomy of Gyrista is the following, with the inclusion of new ochrophyte classes described in 2020 and 2021: *Subphylum Bigyromonada **Class Developea Bigyromonadea **Class Pirsonea *Subphylum Pseudofungi Heterokontimycotina **Class Hyphochytrea Hyphochytriomycota **Class Oomycetes Oomycota ; Peronosporomycetes *Subp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ochrophyta
The ochrophytes, subphylum Ochrophytina, is a group of mostly photosynthetic heterokonts. Their plastid is of red algal origin. The classification of the group is still being worked out. Originally, the ochrophytes were regarded as a phylum denominated Ochrophyta. Some authors (e.g., Cavalier-Smith) divided it into two subphyla, Phaeista Cavalier-Smith 1995 (comprising Hypogyristea and Chrysista in some classifications, or Limnista and Marista in others) and Khakista Cavalier-Smith, 2000 (comprising '' Bolidomonas'' and diatoms). Others prefer not to use the subphyla, listing only lower taxa (e.g., Reviers, 2002, Guiry & Guiry, 2014). However, it is currently regarded as a subphylum inside of the phylum Gyrista, along with Pseudofungi and Bigyromonada. It contains two infraphyla: Diatomista, containing diatoms and related groups, and Chrysista, containing brown and golden algae and related groups. Phylogeny The cladogram below shows the evolutionary relationships be ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ochrophytina
The ochrophytes, subphylum Ochrophytina, is a group of mostly photosynthetic heterokonts. Their plastid is of red algal origin. The classification of the group is still being worked out. Originally, the ochrophytes were regarded as a phylum denominated Ochrophyta. Some authors (e.g., Cavalier-Smith) divided it into two subphyla, Phaeista Cavalier-Smith 1995 (comprising Hypogyristea and Chrysista in some classifications, or Limnista and Marista in others) and Khakista Cavalier-Smith, 2000 (comprising '' Bolidomonas'' and diatoms). Others prefer not to use the subphyla, listing only lower taxa (e.g., Reviers, 2002, Guiry & Guiry, 2014). However, it is currently regarded as a subphylum inside of the phylum Gyrista, along with Pseudofungi and Bigyromonada. It contains two infraphyla: Diatomista, containing diatoms and related groups, and Chrysista, containing brown and golden algae and related groups. Phylogeny The cladogram below shows the evolutionary relationships betwe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stramenopile
Stramenopile is a clade of organisms 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. Members of the clade are referred to as 'stramenopiles'. Stramenopiles are eukaryotes; since they are neither fungi, animals, nor plants, they are classified as protists. Most stramenopiles are single-celled, but some are multicellular algae including some 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. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bigyromonada
Bigyromonadea is a recently described non-photosynthetic lineage of Heterokont Heterokonts are a group of protists (formally referred to as Heterokonta, Heterokontae or Heterokontophyta). The group is a major line of eukaryotes. Most are algae, ranging from the giant multicellular kelp to the unicellular diatoms, which a ...s that at present contains only one species. Taxonomy * Class Bigyromonadea Cavalier-Smith 1998 evelopea Karpov & Aleoshin 2016 ex Cavalier-Smith 2017** Order Developayellales Doweld 2001 evelopayellida Cavalier-Smith 1987*** Family Developayellaceae Cavalier-Smith 1997 evelopayellidae**** Genus '' Developayella'' Tong 1995 ***** Species '' Developayella elegans'' Tong 1995 **** Genus '' Develorapax'' Karpov & Aleoshin 2016 ***** Species '' Develorapax marinus'' Karpov & Aleoshin 2016 References External links {{Taxonbar, from=Q23070368 Heterokont classes Heterokonts ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mastigoneme
Mastigonemes are lateral "hairs" that attach to protistan flagella. Flimsy hairs attach to the flagella of euglenid flagellates, while stiff hairs occur in stramenopile and cryptophyte protists.Hoek, C. van den, Mann, D. G. and Jahns, H. M. (1995). Algae : An introduction to phycology', Cambridge University Press, UK. Stramenopile hairs are approximately 15 nm in diameter, and usually consist of flexible basal part that inserts into the cell membrane, a tubular shaft that itself terminates in smaller "hairs". They reverse the thrust caused when a flagellum beats. The consequence is that the cell is drawn into the water and particles of food are drawn to the surface of heterotrophic species. Typology of flagella with hairs: *whiplash flagella (= smooth, acronematic flagella): without hairs but may have extensions , e.g., in Opisthokonta *hairy flagella (= tinsel, flimmer, pleuronematic flagella): with hairs (= mastigonemes ''sensu lato''), divided in: **with fine hai ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Algae
Algae (; singular alga ) is an informal term for a large and diverse group of photosynthetic eukaryotic organisms. It is a polyphyletic grouping that includes species from multiple distinct clades. Included organisms range from unicellular microalgae, such as ''Chlorella,'' ''Prototheca'' and the diatoms, to multicellular forms, such as the giant kelp, a large brown alga which may grow up to in length. Most are aquatic and autotrophic (they generate food internally) and lack many of the distinct cell and tissue types, such as stomata, xylem and phloem that are found in land plants. The largest and most complex marine algae are called seaweeds, while the most complex freshwater forms are the ''Charophyta'', a division of green algae which includes, for example, ''Spirogyra'' and stoneworts. No definition of algae is generally accepted. One definition is that algae "have chlorophyll ''a'' as their primary photosynthetic pigment and lack a sterile covering of cells around their re ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Platysulcea
''Platysulcus'' is an eukaryotic microorganism that was recently discovered to be the earliest diverging lineage of the Heterokont phylogenetic tree. It is the only member of the family Platysulcidae, order Platysulcida and class Platysulcea, of uncertain taxonomic position within the phylum Bigyra Bigyra is a grouping of heterokont organisms. It includes Bicosoecida, Blastocystis and Labyrinthulida. It has also been described as containing Opalozoa, Bicoecia, and Sagenista. Phylogeny The cladogram below shows the internal relationship .... It contains the only species ''P. tardus''. Taxonomy *Class Platysulcea Cavalier-Smith 2017 **Order Platysulcida Cavalier-Smith 2017 ***Family Platysulcidae Shiratori, Nkayama & Ishida 2015 ****''Platysulcus'' Shiratori, Nkayama & Ishida 2015 *****''P. tardus'' Shiratori, Nkayama & Ishida 2015 References External links {{heterokont-stub Heterokont genera ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Placidozoa
Placidozoa is a recently defined non- photosynthetic lineage of Heterokonts. Phylogeny Taxonomy Infraphylum Placidozoa Cavalier-Smith 2013 * Superclass Wobblata Cavalier-Smith 2006 stat. n. 2013 ( paraphyletic) ** Class Placididea Moriya, Nakayama & Inouye 2002 *** Order Placidida Moriya, Nakayama & Inouye 2002 lacidae Cavalier-Smith 2006**** Family Placidiaceae Moriya, Nakayama & Inouye 2002 ***** Genus '' Pendulomonas'' Tong 1997 ***** Genus ''Placidia'' Moriya, Nakayama & Inouye 2002 ***** Genus '' Wobblia'' Moriya, Nakayama & Inouye 2000 ***** Genus '' Allegra'' Rybarski et al. 2015 ** Class Nanomonadea Cavalier-Smith 2013 *** Order Uniciliatida Cavalier-Smith 2013 **** Family Solenicolidae Cavalier- Smith 2013 ***** Genus ''Solenicola'' Pavillard 1916 **** Family Incisomonadidae Cavalier-Smith & Scoble 2013 ***** Genus '' Incisomonas'' Scoble & Cavalier-Smith 2013 ** Class Opalomonadea Cavalier-Smith 2013 *** Genus '' Barthelona'' Bernard, Simpson & Patterson 2000 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pseudofungi
Pseudofungi is a grouping of heterokonts, also known as the Heterokontimycotina. It consists of the Oomycota and Hyphochytridiomycetes. 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 heterokont chromist algae 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 formula , a polys ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Flagella
A flagellum (; ) is a hairlike appendage that protrudes from certain plant and animal sperm cells, and from a wide range of microorganisms to provide motility. Many protists with flagella are termed as flagellates. A microorganism may have from one to many flagella. A gram-negative bacterium '' Helicobacter pylori'' for example uses its multiple flagella to propel itself through the mucus lining to reach the stomach epithelium, where it may cause a gastric ulcer to develop. In some 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 lash-like swimming motion. The flagellum in archaea is called the archaellum to note its difference from the bacterial flagellum. Eukaryotic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
