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.
Electron micrograph of the protist Paraphysomonas butcheri. It illustrates the stramenopile property - of having stiff hairs. The hairs attach to one longer flagellum, the other is without hairs (an arrangement also called 'heterokont'). The body of the flagellate is coated with delicate scales. Paraphysomonas feeds on bacteria, two of which lie near the hairy flagellum.
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. The tripartite hairs have been lost in some stramenopiles - for example in most diatoms (although these organisms still express mastigonemic proteins - see below).
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; 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 'Stramenopile' was introduced in 1989.[1] It identified a group that overlapped with the ambiguously defined heterokonts.
Schematic drawing of Cafeteria roenbergensis (a heterotrophic bicosoecid), a common bacterivore in marine ecosystems: the anterior flagellum has tripartite hairs and the posterior flagellum is without hairs
The term 'heterokont' is used as both an adjective - indicating that the flagella of flagellated cells are dissimilar - and as the name of a taxon. In the latter context, 'Heterokontae' had been introduced 90 years earlier by Alexander Luther for algae that are now considered the Xanthophyceae.[2]: But the same term was used for other groupings of algae. For example, Copeland[3] 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 the unrelated collar flagellates (as the Choanoflagellata) in which he placed the bicosoecids (a type of stramenopile). 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 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.[4] 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.[5] A taxonomic concept based on a synapomorphy is independent of the organisms that are included. It is stable and robust. New findings may lead to the addition, elimination or regrouping of contained taxa. A synapomorphy-based taxonomic concept is invalidated if the apomorphy in question was found to have evolved on more than one occasion (i.e. is not monophyletic).
At the time of writing, the concept of the taxon Heterokont, as used by some, has evolved to align with that of Stramenopiles.
Two living Cafeteria roenbergensis. Light micrograph. The cells are about 6 µm long. The anterior flagellum beats with an undulating pattern, the posterior (recurrent or smooth) flagellum usually holds the cell to the substrate.
The presumed apomorphy of tripartite flagellar hairs in stramenopiles is well characterized. The basal part of 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 several delicate hairs.[6] The proteins that code for the mastigonemes are also well characterized.[7] As far as we know, these proteins are exclusive to the stramenopile clade, and are present even in taxa (such as diatoms) that no longer have physical hairs.
Most flagellates stramenopiles have two flagella that insert subapically or laterally. They are usually supported by four microtubule roots in a distinctive pattern (details to be included later). There is also a transitional helix inside the flagellum where the beating axoneme with its distinctive 9 peripheral couplets and two central microtubules changes into the nine triplet structure of the basal body.
The current composition of the 'stramenopiles' can be summarized as:
The name of the taxon has also been written as Straminopiles, or more formally as Straminipila. The name "stramenopile" has been discussed by David (2002).[10]
In terms of relatedness among protists, Krylov and co-workers proposed that the morphology of mitochondrial cristae remained relatively unchanged over time, and would define large sectors of protistan diversity.[11] Subsequent molecular studies have confirmed this, with the stramenopiles being most closely related to Alveolates and Rhizaria - all with tubular mitochondrial cristae and collectively referred to as the SAR clade.[12]
Stramenochromes
The stramenopiles with plastids (stramenochromes)[13] have plastids with an off-green, orange, golden or brown color because of the occurrence of chlorophyll a, chlorophyll c, and fucoxanthin. This form of plastid is referred to as a chromoplast (as opposed to chloroplast which if used narrowly refers to the chlorophyll B containing plastids in green algae, some euglenids, and the land plants). 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.
Chromoplasts are surrounded by four membranes. The outermost is continuous with the chloroplast endoplasmic reticulum, or cER. The second membrane presents a barrier between the lumen of the cER and the primary endosymbiont or chloroplast. The symbiont was the source of the two innermost membranes within which the thylakoid membranes are found.
Most molecular analyses suggest that the most basal stramenopiles are colorless heterotrophs.[14][15] This suggests that the stramenopiles arose as heterotrophic organisms, diversified, and only at a later stage in their evolutionary history did they acquire chromoplasts. Some lineages (such as the axodine lineage that included the chromophytic pedinellids, colourless ciliophryids, and colourless actinophryid heliozoa) have secondarily reverted to heterotrophy.
Significance
Some stramenopiles are significant as autotrophs and as heterotrophs in natural ecosystems. Blastocystis is a parasite of humans; opalines and proteromonads live in the intestines of cold-blooded vertebrates; oomycetes include some significant plant pathogens (including the agent that caused the potato blight famine in Ireland that resulted in approximately one million deaths and led to extensive emigration). Diatoms are major contributors to global carbon cycles because they are the most important autotrophs in most marine habitats. The brown algae (or kelp) are major autotrophs of 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.
^Patterson, D. J. 1989. Stramenopiles: chromophytes from a protistological perspective. In: Green, J.C., Leadbeater, B.S.C. & Diver, W. L. 1989. The chromophyte algae: problems and perspectives. Clarendon Press, Oxford. 357-379
^Luther, Alexander F. (1899). Über Chlorosaccus eine neue Gattung der Süsswasseralgen nebst einiger Bemerkungen zur Systematik verwandter Algen. Stockholm: Norstedt. pp. 1–22.
^Copeland, H. F. 1956. The Classification of Lower organisms. Pacific Books, Palo Alto, California
^Blackwell, W. H. (2009). "Chromista revisited: A dilemma of overlapping putative kingdoms, and the attempted application of the botanical code of nomenclature" (PDF). Phytologia. 91 (2).
^Patterson, Colin (1982). "Morphological characters and homology, in Joysey, Kenneth A; Friday, A. E. (eds), Problems in Phylogenetic Reconstruction, Systematics Association Special Volume 21, London: Academic Press". {{cite journal}}: Cite journal requires |journal= (help)
^Bouck, G.B. 1971. The structure, origin, and composition of the tubular mastigonemes of the Ochromonas flagellum. J. Cell. Biol., 50: 362-384
^Blackman, L.M., Arikawa, M., Yamada, S., Suzaki, T., & Hardham, A. R. 2011. Identification of a Mastigoneme Protein from Phytophthora nicotianae. Protist 162: 100-114, https://doi.org/10.1016/j.protis.2010.01.005.
^Graf, Louis; Yoon, Hwan Su (21 July 2021). "Olisthodiscophyceae, the 17th heterokont algal class". Journal of Phycology. 57 (4): 1091–1093. doi:10.1111/jpy.13184. ISSN 0022-3646. PMID 34289104. S2CID 236175098.
^Barcytė, Dovilė; Eikrem, Wenche; Engesmo, Anette; Seoane, Sergio; Wohlmann, Jens; Horák, Aleš; Yurchenko, Tatiana; Eliáš, Marek (2 March 2021). "Olisthodiscus represents a new class of Ochrophyta". Journal of Phycology. 57 (4): 1094–1118. doi:10.1111/jpy.13155. PMID 33655496. S2CID 232101186.
^David, J.C. 2002. A preliminary catalogue of the names of fungi above the rank of order. Constancea. 83: 1–30
^Krylov, M. V., A. A. Dobrovolskii, I. V. Issi, B. I. Michaelevich, S. A. Podlipaev, V. V. Reshetnyak, L. N. Seravin, et al. 1980. New concepts for the system of unicellular organisms. Trudy Zoologischkei Institut Akademiya Na�yuk, SSSR 94:122–132.
^Derelle R, López-García P, Timpano H, Moreira D. A Phylogenomic Framework to Study the Diversity and Evolution of Stramenopiles (= Heterokonts). Mol Biol Evol. 2016 Nov;33(11):2890-2898. doi: 10.1093/molbev/msw168. Epub 2016 Aug 10. PMID 27512113; PMCID: PMC5482393.
^Leipe, D. D., P. O. Wainright, J. H. Gunderson, D. Porter, D. J. Patterson, F. Valois, S. Himmerich and M. L. Sogin. 1994. The stramenopiles from a molecular perspective: 16S-like rRNA sequences from Labyrinthuloides minuta and Cafeteria roenbergensis. Phycologia 33: 369-377
^Leyland, B., Leu, S., Boussiba, S. 2017. Are Thraustochytrids algae? Fungal Biology,121:835-840
^Derelle R, López-García P, Timpano H, Moreira D. A Phylogenomic Framework to Study the Diversity and Evolution of Stramenopiles (= Heterokonts). Mol Biol Evol. 2016 Nov;33(11):2890-2898. doi: 10.1093/molbev/msw168. Epub 2016 Aug 10. PMID 27512113; PMCID: PMC5482393.
External links
Tree of Life Web Project: Stramenopiles
December 28, 2022
stramenopile, clade, organisms, distinguished, presence, stiff, tripartite, external, hairs, most, species, hairs, attached, flagella, some, they, attached, other, areas, cellular, surface, some, they, have, been, secondarily, lost, which, case, relatedness, s. 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 Electron micrograph of the protist Paraphysomonas butcheri It illustrates the stramenopile property of having stiff hairs The hairs attach to one longer flagellum the other is without hairs an arrangement also called heterokont The body of the flagellate is coated with delicate scales Paraphysomonas feeds on bacteria two of which lie near the hairy flagellum 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 The tripartite hairs have been lost in some stramenopiles for example in most diatoms although these organisms still express mastigonemic proteins see below 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 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 Contents 1 History and the Heterokont problem 2 Stramenochromes 3 Significance 4 Gallery 5 References 6 External linksHistory and the Heterokont problem EditThe term Stramenopile was introduced in 1989 1 It identified a group that overlapped with the ambiguously defined heterokonts Schematic drawing of Cafeteria roenbergensis a heterotrophic bicosoecid a common bacterivore in marine ecosystems the anterior flagellum has tripartite hairs and the posterior flagellum is without hairs The term heterokont is used as both an adjective indicating that the flagella of flagellated cells are dissimilar and as the name of a taxon In the latter context Heterokontae had been introduced 90 years earlier by Alexander Luther for algae that are now considered the Xanthophyceae 2 But the same term was used for other groupings of algae For example Copeland 3 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 the unrelated collar flagellates as the Choanoflagellata in which he placed the bicosoecids a type of stramenopile 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 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 4 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 5 A taxonomic concept based on a synapomorphy is independent of the organisms that are included It is stable and robust New findings may lead to the addition elimination or regrouping of contained taxa A synapomorphy based taxonomic concept is invalidated if the apomorphy in question was found to have evolved on more than one occasion i e is not monophyletic At the time of writing the concept of the taxon Heterokont as used by some has evolved to align with that of Stramenopiles Two living Cafeteria roenbergensis Light micrograph The cells are about 6 µm long The anterior flagellum beats with an undulating pattern the posterior recurrent or smooth flagellum usually holds the cell to the substrate The presumed apomorphy of tripartite flagellar hairs in stramenopiles is well characterized The basal part of 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 several delicate hairs 6 The proteins that code for the mastigonemes are also well characterized 7 As far as we know these proteins are exclusive to the stramenopile clade and are present even in taxa such as diatoms that no longer have physical hairs Most flagellates stramenopiles have two flagella that insert subapically or laterally They are usually supported by four microtubule roots in a distinctive pattern details to be included later There is also a transitional helix inside the flagellum where the beating axoneme with its distinctive 9 peripheral couplets and two central microtubules changes into the nine triplet structure of the basal body The current composition of the stramenopiles can be summarized as Stramenopiles without chloroplasts Oomycetes water molds Hyphochytridiomycetes Developayellids also referred to as Bigyromonadea Bicosoecea Labyrinthulomycetes slime nets inclusive of thraustrochytids Opalinesa Proteromonadsea BlastocystisStramenopiles with chloroplasts Stramenochromes Axodines Pedinellids and aplastidic actinophryid heliozoa Bacillariophyceae diatoms Bolidophyceae Chrysomerophyceae Chrysophyceae golden algae Dictyochophyceae Eustigmatophyceae Olisthodiscophyceae Barcyte Eikrem amp M Elias 2021 8 9 Pelagophyceae Phaeothamniophyceae Phaeophyceae brown algae Pinguiophyceae Raphidophyceae Synchromophyceae Synurophyceae Xanthophyceae yellow green algae Opalina ranarum light micrograph of living cell The name of the taxon has also been written as Straminopiles or more formally as Straminipila The name stramenopile has been discussed by David 2002 10 In terms of relatedness among protists Krylov and co workers proposed that the morphology of mitochondrial cristae remained relatively unchanged over time and would define large sectors of protistan diversity 11 Subsequent molecular studies have confirmed this with the stramenopiles being most closely related to Alveolates and Rhizaria all with tubular mitochondrial cristae and collectively referred to as the SAR clade 12 Stramenochromes EditThe stramenopiles with plastids stramenochromes 13 have plastids with an off green orange golden or brown color because of the occurrence of chlorophyll a chlorophyll c and fucoxanthin This form of plastid is referred to as a chromoplast as opposed to chloroplast which if used narrowly refers to the chlorophyll B containing plastids in green algae some euglenids and the land plants 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 Chromoplasts are surrounded by four membranes The outermost is continuous with the chloroplast endoplasmic reticulum or cER The second membrane presents a barrier between the lumen of the cER and the primary endosymbiont or chloroplast The symbiont was the source of the two innermost membranes within which the thylakoid membranes are found Most molecular analyses suggest that the most basal stramenopiles are colorless heterotrophs 14 15 This suggests that the stramenopiles arose as heterotrophic organisms diversified and only at a later stage in their evolutionary history did they acquire chromoplasts Some lineages such as the axodine lineage that included the chromophytic pedinellids colourless ciliophryids and colourless actinophryid heliozoa have secondarily reverted to heterotrophy Significance EditSome stramenopiles are significant as autotrophs and as heterotrophs in natural ecosystems Blastocystis is a parasite of humans opalines and proteromonads live in the intestines of cold blooded vertebrates oomycetes include some significant plant pathogens including the agent that caused the potato blight famine in Ireland that resulted in approximately one million deaths and led to extensive emigration Diatoms are major contributors to global carbon cycles because they are the most important autotrophs in most marine habitats The brown algae or kelp are major autotrophs of 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 Gallery Edit Labyrinthula Labyrinthulea Anthophysa Stramenopile Paraphysomonas Stramenopile Blastocystis hominis Blastocystea Zelleriella Opalinea Protoopalina pingi Opalinea Peronospora sparsa Oomycetes Potatoes with Phytophthora Oomycetes Diatoms Bacillariophyceae Silicoflagellate Dictyochophyceae Actinomonas Stramenopile Ciliophrys Stramenopile Actinophrys sol Actinophryida Nannochloropsis sp Eustigmatophyceae Dinobryon sp Chrysophyceae Synura sp Synurophyceae Haramonas Raphidophyceae Ophiocytium Xanthophyta Fucus vesiculosus Phaeophyceae References Edit Patterson D J 1989 Stramenopiles chromophytes from a protistological perspective In Green J C Leadbeater B S C amp Diver W L 1989 The chromophyte algae problems and perspectives Clarendon Press Oxford 357 379 Luther Alexander F 1899 Uber Chlorosaccus eine neue Gattung der Susswasseralgen nebst einiger Bemerkungen zur Systematik verwandter Algen Stockholm Norstedt pp 1 22 Copeland H F 1956 The Classification of Lower organisms Pacific Books Palo Alto California Blackwell W H 2009 Chromista revisited A dilemma of overlapping putative kingdoms and the attempted application of the botanical code of nomenclature PDF Phytologia 91 2 Patterson Colin 1982 Morphological characters and homology in Joysey Kenneth A Friday A E eds Problems in Phylogenetic Reconstruction Systematics Association Special Volume 21 London Academic Press a href Template Cite journal html title Template Cite journal cite journal a Cite journal requires journal help Bouck G B 1971 The structure origin and composition of the tubular mastigonemes of the Ochromonas flagellum J Cell Biol 50 362 384 Blackman L M Arikawa M Yamada S Suzaki T amp Hardham A R 2011 Identification of a Mastigoneme Protein from Phytophthora nicotianae Protist 162 100 114 https doi org 10 1016 j protis 2010 01 005 Graf Louis Yoon Hwan Su 21 July 2021 Olisthodiscophyceae the 17th heterokont algal class Journal of Phycology 57 4 1091 1093 doi 10 1111 jpy 13184 ISSN 0022 3646 PMID 34289104 S2CID 236175098 Barcyte Dovile Eikrem Wenche Engesmo Anette Seoane Sergio Wohlmann Jens Horak Ales Yurchenko Tatiana Elias Marek 2 March 2021 Olisthodiscus represents a new class of Ochrophyta Journal of Phycology 57 4 1094 1118 doi 10 1111 jpy 13155 PMID 33655496 S2CID 232101186 David J C 2002 A preliminary catalogue of the names of fungi above the rank of order Constancea 83 1 30 Krylov M V A A Dobrovolskii I V Issi B I Michaelevich S A Podlipaev V V Reshetnyak L N Seravin et al 1980 New concepts for the system of unicellular organisms Trudy Zoologischkei Institut Akademiya Na yuk SSSR 94 122 132 Derelle R Lopez Garcia P Timpano H Moreira D A Phylogenomic Framework to Study the Diversity and Evolution of Stramenopiles Heterokonts Mol Biol Evol 2016 Nov 33 11 2890 2898 doi 10 1093 molbev msw168 Epub 2016 Aug 10 PMID 27512113 PMCID PMC5482393 Leipe D D P O Wainright J H Gunderson D Porter D J Patterson F Valois S Himmerich and M L Sogin 1994 The stramenopiles from a molecular perspective 16S like rRNA sequences from Labyrinthuloides minuta and Cafeteria roenbergensis Phycologia 33 369 377 Leyland B Leu S Boussiba S 2017 Are Thraustochytrids algae Fungal Biology 121 835 840 Derelle R Lopez Garcia P Timpano H Moreira D A Phylogenomic Framework to Study the Diversity and Evolution of Stramenopiles Heterokonts Mol Biol Evol 2016 Nov 33 11 2890 2898 doi 10 1093 molbev msw168 Epub 2016 Aug 10 PMID 27512113 PMCID PMC5482393 External links EditTree of Life Web Project Stramenopiles Retrieved from https en wikipedia org w index php title Stramenopile amp oldid 1128557946, wikipedia, wiki, book, books, library,
