30-545: Heterokontimycotina M.W. Dick, 1976 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). It
60-451: A more ancient origin of stramenopile characteristics. Telonemia [REDACTED] Rhizaria [REDACTED] Stramenopiles [REDACTED] Alveolata [REDACTED] The following cladogram summarizes the evolutionary relationships between Stramenopiles. The phylogenetic relationships of Bigyra vary greatly from one analysis to the next: it has been recovered as either monophyletic or paraphyletic . When paraphyletic,
90-426: A single pore. The surface of mature cysts may be ornamented with different structural elements and are useful to distinguish species. Classification of the class Chrysophyceae according to Pascher (1914): According to Smith (1938) : According to Bourrely (1957): According to Starmach (1985): Classification of the class Chrysophyceae and splinter groups according to Kristiansen (1986): Classification of
120-674: A single species, Prymnesium parvum , which causes fish kills . The Chrysophyceae should not be confused with the Chrysophyta , which is a more ambiguous taxon . Although "chrysophytes" is the anglicization of "Chrysophyta", it generally refers to the Chrysophyceae. Originally they were taken to include all such forms of the diatoms and multicellular brown algae , but since then they have been divided into several different groups (e.g., Haptophyceae , Synurophyceae ) based on pigmentation and cell structure. Some heterotrophic flagellates as
150-496: Is a gastrointestinal parasite of humans; opalines and proteromonads live in the intestines of cold-blooded vertebrates and have been described as parasitic; oomycetes include some significant plant pathogens such as the cause of potato blight, Phytophthora infestans . Diatoms are major contributors to global carbon cycles because they are the most important autotrophs in most marine habitats. The brown algae, including familiar seaweeds like wrack and kelp, are major autotrophs of
180-469: 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
210-584: Is formed from their initials. The ancestor of the SAR supergroup appears to have captured a unicellular photosynthetic red alga , and many Stramenopiles, as well as members of other SAR groups such as the Rhizaria, still have plastids which retain the double membrane of the red alga and a double membrane surrounding it, for a total of four membranes. In addition, species of Telonemia , the sister group to SAR, exhibit heterokont flagella with tripartite mastigonemes, implying
240-412: Is oriented toward the moving direction. The smooth passive flagellum, oriented toward the opposite direction, may be present only in rudimentary form in some species. An important characteristic used to identify members of the class Chrysophyceae is the presence of a siliceous cyst that is formed endogenously. Called statospore , stomatocyst or statocyst , this structure is usually globose and contains
270-453: Is rare, such that when the taxon name is used, it is unclear how it should be understood. The term 'Heterokont' has lost its usefulness in critical discussions about the identity, nature, character and relatedness of the group. The term 'stramenopile' sought to identify a clade (monophyletic and holophyletic lineage) using the approach developed by transformed cladists of pointing to a defining innovative characteristic or apomorphy. Over time,
300-423: The bicosoecids and choanoflagellates were sometimes seen as related to golden algae too. They are now usually restricted to a core group of closely related forms, distinguished primarily by the structure of the flagella in motile cells, also treated as an order Chromulinales. It is possible membership will be revised further as more species are studied in detail. The Chrysophyceae have been placed by some in
330-585: 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 diatoms . Many stramenopiles are unicellular flagellates , and most others produce flagellated cells at some point in their lifecycles, for instance as gametes or zoospores . Most flagellated heterokonts have two flagella;
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#1733084618209360-429: The 'core heterokonts' (those having anterior flagella with stiff hairs). Newly recognized relatives included the parasitic opalines , proteromonads , and actinophryid heliozoa . They joined other heterotrophic protists, such as bicosoecids , labyrinthulids , and oomycete fungi, that were included by some as heterokonts and excluded by others. Rather than continue to use a name whose meaning had changed over time and
390-403: The 'heterokont problem', now resolved by the definition of the stramenopiles. The term 'stramenopile' was introduced by D. J. Patterson in 1989, defining a group that overlapped with the ambiguously defined heterokonts . The name "stramenopile" has been discussed by J. C. David. The term 'heterokont' is used as both an adjective – indicating that a cell has two dissimilar flagella – and as
420-472: The Stramenopiles according to Adl et al. (2019), with additions from newer research: Chrysophyte Chromulinales Chrysosphaerales Hibberdiales Hydrurales Phaeothamniales The Chrysophyceae , usually called chrysophytes , chrysomonads , golden-brown algae or golden algae , are a large group of algae , found mostly in freshwater. Golden algae is also commonly used to refer to
450-421: The anterior flagellum has one or two rows of stiff hairs or mastigonemes , and the posterior flagellum is without such embellishments, being smooth, usually shorter, or in a few cases not projecting from the cell. The term 'heterokont' is used both as an adjective – indicating that a cell has two dissimilar flagella, and as the name of a taxon. The groups included in that taxon have however varied widely, creating
480-518: The apex. They are usually supported by four microtubule roots in a distinctive pattern. There is a transitional helix inside the flagellum where the beating axoneme with its distinctive geometric pattern of nine peripheral couplets around two central microtubules changes into the nine-triplet structure of the basal body. Many stramenopiles have plastids which enable them to photosynthesise , using light to make their own food . Those plastids are coloured off-green, orange, golden or brown because of
510-799: The branching order of the bigyran groups also varies: in some studies Sagenista is the most basal-branching clade, while in others Opalozoa is the most basal. Nonetheless, Platysulcea is consistently recovered as the sister clade to all other stramenopiles. In addition, a flagellate species discovered in 2023, Kaonashia insperata , remains in an uncertain phylogenetic position, but more closely related to Gyrista than to other clades. Platysulcus Labyrinthulomycetes [REDACTED] Eogyrea Placididea Nanomonadea Opalinata [REDACTED] Bicosoecida [REDACTED] Developea Pirsonea Hyphochytriomycetes Oomycetes [REDACTED] Ochrophyta (=Heterokontophyta) [REDACTED] Kaonashia The classification of
540-444: The development of convergent fungal multicellularity, explaining why the cell wall is sometimes made of both chitin and cellulose . The group's interrelationships are as follows: Developayella Oomycetes Hyphochytriomycetes Heterokont The Stramenopiles , also called Heterokonts , are a clade of organisms distinguished by the presence of stiff tripartite external hairs. In most species,
570-430: The hair is flexible and inserts into the cell membrane; the second part is dominated by a long stiff tube (the 'straw' or 'stramen'); and finally the tube is tipped by many delicate hairs called mastigonemes . The proteins that code for the mastigonemes appear to be exclusive to the stramenopile clade, and are present even in taxa (such as diatoms) that no longer have such hairs. Most stramenopiles have two flagella near
600-558: 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,
630-424: The intertidal and subtidal marine habitats. Some of the bacterivorous stramenopiles, such as Cafeteria , are common and widespread consumers of bacteria, and thus play a major role in recycling carbon and nutrients within microbial food webs . Stramenopiles are most closely related to Alveolates and Rhizaria, all of which have tubular mitochondrial cristae and collectively form the SAR supergroup , whose name
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#1733084618209660-492: The name of a taxon. The taxon 'Heterokontae' was introduced in 1899 by Alexander Luther for algae that are now considered the Xanthophyceae . But the same term was used for other groupings of algae. For example, in 1956, Copeland used it to include the xanthophytes (using the name Vaucheriacea), a group that included what became known as the chrysophytes , the silicoflagellates , and the hyphochytrids . Copeland also included
690-511: The phylum Chrysophyta according to Margulis et al. (1990): According to van den Hoek, Mann and Jahns (1995) : Classification of the class Chrysophyceae and splinter groups according to Preisig (1995): According to Guiry and Guiry (2019): Chrysophytes live mostly in freshwater , and are important for studies of food web dynamics in oligotrophic freshwater ecosystems, and for assessment of environmental degradation resulting from eutrophication and acid rain . Chrysophytes contain
720-564: The pigment fucoxanthin . Because of this, they were once considered to be a specialized form of cyanobacteria . Because many of these organisms had a silica capsule, they have a relatively complete fossil record, allowing modern biologists to confirm that they are, in fact, not derived from cyanobacteria, but rather an ancestor that did not possess the capability to photosynthesize. Many of the chrysophyta precursor fossils entirely lacked any type of photosynthesis-capable pigment. The most primitive stramenopiles are regarded as heterotrophic, such as
750-449: The polyphyletic Chromista . The broader monophyletic group to which the Chrysophyceae belong includes various non-algae including the bicosoecids, not the collar flagellates, opalines, oomycete fungi, proteromonads, actinophryid heliozoa, and other heterotrophic flagellates and is referred to as the Stramenopiles . The "primary" cell of chrysophytes contains two specialized flagella . The active, "feathered" (with mastigonemes ) flagellum
780-532: The presence of chlorophyll a , chlorophyll c , and fucoxanthin . This form of plastid is called a stramenochrome or chromoplast . The most significant autotrophic stramenopiles are the brown algae (wracks and many other seaweeds), and the diatoms . The latter are among the most significant primary producers in marine and freshwater ecosystems. Most molecular analyses suggest that the most basal stramenopiles lacked plastids and were accordingly colourless heterotrophs , feeding on other organisms. This implies that
810-504: The scope of application has changed, especially when in the 1970s ultrastructural studies revealed greater diversity among the algae with chromoplasts (chlorophylls a and c) than had previously been recognized. At the same time, a protistological perspective was replacing the 19th century one based on the division of unicellular eukaryotes into animals and plants. One consequence was that an array of heterotrophic organisms, many not previously considered as 'heterokonts', were seen as related to
840-429: The stramenopiles arose as heterotrophs, diversified, and then some of them acquired chromoplasts. Some lineages (such as the axodine lineage that included the chromophytic pedinellids , colourless ciliophryids, and colourless actinophryid heliozoa) have secondarily reverted to heterotrophy. Some stramenopiles are significant as autotrophs and as heterotrophs in natural ecosystems; others are parasitic. Blastocystis
870-426: The unrelated collar flagellates (as the choanoflagellates ) in which he placed the bicosoecids . He also included the not-closely related haptophytes . The consequence of associating multiple concepts to the taxon 'heterokont' is that the meaning of 'heterokont' can only be made clear by making reference to its usage: Heterokontae sensu Luther 1899; Heterokontae sensu Copeland 1956, etc. This contextual clarification
900-403: Was hence ambiguous, the name 'stramenopile' was introduced to refer to the clade of protists that had tripartite stiff (usually flagellar) hairs and all their descendants. Molecular studies confirm that the genes that code for the proteins of these hairs are exclusive to stramenopiles. The presumed apomorphy of tripartite flagellar hairs in stramenopiles is well characterized. The basal part of
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