Stramenopile

This is a good article. Click here for more information.
Source: Wikipedia, the free encyclopedia.

Stramenopiles
Temporal range: Late Mesoproterozoic-present, 1025–0 Ma[1]
KelpOomyceteBicosoecidDiatomLabyrinthulomycetesOpalineYellow-green algaeGolden algaeSilicoflagellate
Diversity of stramenopiles
Scientific classification Edit this classification
Domain: Eukaryota
Clade: Diaphoretickes
Clade: SAR
Clade: Stramenopiles
Patterson 1989[2] emend. Adl et al. 2005[3]
Phyla and subphyla[4]
Diversity
>100000 species[1]
Synonyms

The Stramenopiles, also called Heterokonts, are a

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

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

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 the 'heterokont problem', now resolved by the definition of the stramenopiles.

History

The term 'stramenopile' was introduced by

heterokonts.[12][13] The name "stramenopile" has been discussed by J. C. David.[14]

The heterokont problem

The term 'heterokont' is used as both an adjective – indicating that a cell has two dissimilar flagella – and as the name of a taxon. The taxon 'Heterokontae' was introduced in 1899 by Alexander Luther for algae that are now considered 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 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.[17] 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.[18]

Over time, 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 the 'core heterokonts' (those having anterior flagella with stiff hairs). Newly recognized relatives included the parasitic

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 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.[19]

Characteristics

bicosoecid), a common bacterivore in marine ecosystems: the anterior flagellum is tripartite and covered with hairs (mastigonemes); the posterior flagellum is without hairs.
Two living C. 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 many delicate hairs called mastigonemes.[20] 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.[21]

Most stramenopiles have two flagella near the apex.[22] 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.[23]

Plastids

Many stramenopiles have

pedinellids, colourless ciliophryids, and colourless actinophryid heliozoa) have secondarily reverted to heterotrophy.[25][26]

Ecology

Phaeophyceae
, within the Gyrista.

Some stramenopiles are significant as autotrophs and as heterotrophs in natural ecosystems; others are parasitic. Blastocystis is a gastrointestinal parasite of humans;[27] opalines and proteromonads live in the intestines of cold-blooded vertebrates and have been described as parasitic;[28] oomycetes include some significant plant pathogens such as the cause of potato blight, Phytophthora infestans.[29] Diatoms are major contributors to global carbon cycles because they are the most important autotrophs in most marine habitats.[30] The brown algae, including familiar seaweeds like wrack and kelp, are major autotrophs of the intertidal and subtidal marine habitats.[31] 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.[32][33]

Evolution

External

Stramenopiles are most closely related to Alveolates and Rhizaria, all of which have tubular mitochondrial cristae and collectively form the SAR supergroup, whose name is formed from their initials.[34][26][35] 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.[36] In addition, species of Telonemia, the sister group to SAR, exhibit heterokont flagella with tripartite mastigonemes, implying a more ancient origin of stramenopile characteristics.[37]

TSAR

Telonemia

SAR

Rhizaria

Halvaria

Stramenopiles

Alveolata

Internal

The following

sister clade to all other stramenopiles.[39][40] 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.[41]

Stramenopiles

Platysulcus

Gyrista 
Bigyromonada

Developea

Pirsonea

Pseudofungi

Ochrophyta (=Heterokontophyta)

Kaonashia

Classification

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', meaning "unequal"). The body of the flagellate is coated with delicate scales. Paraphysomonas feeds on bacteria, two of which lie near the hairy flagellum.

The classification of the Stramenopiles according to Adl et al. (2019), with additions from newer research:[43] [4]

  • Platysulcea Cavalier-Smith 2017[39]
  • Bigyra Cavalier-Smith 1998, emend. 2006
  • Gyrista Cavalier-Smith 1998
    • Bigyromonada Cavalier-Smith 1998
      • Developea
        Karpov & Aleoshin 2016
      • Pirsoniales
        Cavalier-Smith 1998, emend. 2006
    • Pseudofungi Cavalier-Smith 1986
      • Hyphochytriales
        Sparrow 1960
      • Peronosporomycetes
        Dick 2001 [=Oomycetes Winter 1897, emend. Dick 1976]
    • Actinophryidae
      Claus 1874, emend. Hartmann 1926
    • Ochrophyta
      Cavalier-Smith 1986, emend. Cavalier-Smith & Chao 1996
      • Chrysista
        Cavalier-Smith 1986
        • Chrysoparadoxophyceae Wetherbee 2019[44]
        • Chrysophyceae
          Pascher 1914
        • Chloromorophyceae (nomen dubium)[45]
        • Eustigmatophyceae
          Hibberd & Leedale 1971
        • Olisthodiscophyceae Barcytė, Eikrem & M.Eliáš, 2021[46][47]
        • Phaeophyceae
          Hansgirg 1886
        • Phaeosacciophyceae R.A.Andersen, L.Graf & H.S.Yoon 2020[48]
        • Phaeothamniophyceae
          Andersen & Bailey in Bailey et al. 1998
        • Raphidophyceae
          Chadefaud 1950, emend. Silva 1980
        • Schizocladiophyceae Henry, Okuda & Kawai, 2003
        • Synchromophyceae
          S.Horn & C.Wilhelm 2007 [=Picophagea Cavalier-Smith 2006, emend. 2017]
        • Xanthophyceae
          Allorge 1930, emend. Fritsch 1935 [Heterokontae Luther 1899; Heteromonadea Leedale 1983; Xanthophyta Hibberd 1990]
      • Diatomista
        Derelle et al. 2016, emend. Cavalier-Smith 2017
        • Bolidophyceae Guillou et al. 1999
        • Diatomeae
          Dumortier 1821 [=Bacillariophyta Haeckel 1878]
        • Dictyochophyceae Silva 1980
        • Pelagophyceae
          Andersen & Saunders 1993
        • Pinguiophyceae
          Kawachi et al. 2003

Notes

  1. land plants
    .

References

  1. ^
    doi:10.1016/B978-012373944-5.00253-4
    . Retrieved 2 March 2024.
  2. ISBN 978-0198577133
    .
  3. Wikidata Q22065654
    .
  4. ^
    PMID 28875267
    .
  5. S2CID 221852241
    .
  6. ^ David, J.C. (2002). "A preliminary catalogue of the names of fungi above the rank of order". Constancea. 83: 1–30.
  7. ISBN 978-0-948737-00-8
    .
  8. ISBN 978-0-521-30419-1
    .
  9. ISBN 978-0471522294
    .
  10. ISBN 978-94-015-9733-3
    .
  11. ^ "Stramenipila M.W. Dick (2001)". MycoBank. International Mycological Association.
  12. ^ Patterson, D. J. (1989). "Stramenopiles: chromophytes from a protistological perspective". In Green, J. C.; Leadbeater, B. S. C.; Diver, W. L. (eds.). The chromophyte algae: problems and perspectives. Oxford: Clarendon Press. pp. 357–379.
  13. S2CID 4367158
    .
  14. ^ David, J. C. (2002). "A preliminary catalogue of the names of fungi above the rank of order". Constancea (83): 1–30.
  15. ^ Luther, Alexander F. (1899). Über Chlorosaccus eine neue Gattung der Süsswasseralgen nebst einiger Bemerkungen zur Systematik verwandter Algen [About Chlorosaccus a new genus of freshwater algae together with some comments on the systematics of related algae] (in German). Stockholm: Norstedt. pp. 1–22.
  16. ^ Copeland, H. F. (1956). The Classification of Lower Organisms. Palo Alto, California: Pacific Books.
  17. ^ 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).
  18. ISBN 978-0-1239-1250-3
    .
  19. S2CID 52947780
    .
  20. PMID 5123323
    .
  21. PMID 20663714
    .
  22. ISBN 9780123739445
    .
  23. S2CID 7936118
    .
  24. doi:10.2216/i0031-8884-33-5-369.1
    .
  25. PMID 28889907
    .
  26. ^
    PMID 27512113
    .
  27. PMID 24883113
    .
  28. OCLC 13123309
    .
  29. PMID 30731850
    .
  30. S2CID 16849373
    .
  31. PMID 21820616
    .
  32. ^ Guiry, Wendy (7 April 2011). "Cafeteria T.Fenchel & D.J.Patterson 1988". AlgaeBase. Retrieved 17 March 2023.
  33. ^ Fenchel, T.; Patterson, D. J. (1988). "Cafeteria roenbergensis nov. gen., nov. sp., a heterotrophic microflagellate from marine plankton". Marine Microbial Food Webs. 3: 9–19.
  34. ^ Krylov, M. V.; Dobrovolskii, A. A.; Issi, I. V.; Michaelevich, B. I.; Podlipaev, S. A.; Reshetnyak, V. V.; Seravin, L. N.; et al. 1980. New concepts for the system of unicellular organisms. Trudy Zoologischkei Institut Akademiya Nayuk, SSSR 94:122–132.
  35. PMID 18522922
    .
  36. PMID 24016529
    .
  37. PMID 35291881
    .
  38. ^
    PMID 23219323
    .
  39. ^
    S2CID 202865459
    .
  40. ^
    PMID 28822908
    .
  41. ^
    Wikidata Q123562228
    .
  42. Wikidata Q124719861
    .
  43. PMID 30257078
    .
  44. S2CID 54477112
    .
  45. ^ Medlin LK, Desdevises Y (2018). "Sequence analysis confirms a new algal class". Vie et Milieu/Life & Environment.
  46. S2CID 236175098
    .
  47. S2CID 232101186
    .
  48. S2CID 227315556
    .

External links
Retrieved from "https://en.wikipedia.org/w/index.php?title=Stramenopile&oldid=1219360254"