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Centrohelid

April 15, 2024

The centrohelids or centroheliozoa are a large group of heliozoan protists.[4] They include both mobile and sessile forms, found in freshwater and marine environments, especially at some depth.

Centrohelids
Raphidiophrys contractilis
Scientific classification
Domain: Eukaryota
Clade: Diaphoretickes
Phylum: Haptista
Class: Centroplasthelida
Febvre‐Chevalier & Febvre, 1984[1]
Orders[1][2]
  • Pterocystida
    • Raphidista
    • Pterista
  • Panacanthocystida

Incertae sedis

  • Spiculophryidae
  • Parasphaerastrum
  • Heteroraphidiophrys
Synonyms
  • Centroplastiales
  • Centrohelina Hartmann 1913
  • Centroheliozoa Cushman & Jarvis 1929 sensu Durrschmidt & Patterson 1987
  • Centrohelida Kühn 1926[3]
  • Centrohelea Kuhn 1926 stat. n. Cavalier-Smith 1993

Characteristics edit

 
Diagram of a centrohelid cell.

Individuals are unicellular and spherical, usually around 30–80 μm in diameter, and covered with long radial axopods, narrow cellular projections that capture food and allow mobile forms to move about.

A few genera have no cell covering, but most have a gelatinous coat holding scales and spines, produced in special deposition vesicles. These may be organic or siliceous and come in various shapes and sizes. For instance, in Raphidiophrys the coat extends along the bases of the axopods, covering them with curved spicules that give them a pine-treeish look, and in Raphidiocystis there are both short cup-shaped spicules and long tubular spicules that are only a little shorter than the axopods. Some other common genera include Heterophrys, Actinocystis, and Oxnerella.

The axopods of centrohelids are supported by microtubules in a triangular-hexagonal array, which arise from a tripartite granule called the centroplast at the center of the cell. Axopods with a similar array occur in gymnosphaerids, which have traditionally been considered centrohelids (though sometimes in a separate order from the others). This was questioned when it was found they have mitochondria with tubular cristae, as do other heliozoa, while in centrohelids the cristae are flat. Although this is no longer considered a very reliable character, on balance gymnosphaerids seem to be a separate group.

Taxonomy edit

History edit

The evolutionary position of the centrohelids is not clear. Structural comparisons with other groups are difficult, in part because no flagella occur among centrohelids, and genetic studies have been more or less inconclusive. Cavalier-Smith has suggested they may be related to the Rhizaria,[5] but for the most part they are left with uncertain relations to other groups. A 2009 paper suggests that they may be related to the cryptophytes and haptophytes (see Cryptomonads-haptophytes assemblage).[6] They are currently classified as Hacrobia, under the Plants+HC clade, although some research studies have found evidence against the monophyly of this group.[7] Centrohelids were previously divided into two orders with contrasting scale morphology and ultrastructure: Pterocystida and Acanthocystida.[8] Posterior molecular studies of 2018 have rearranged the classification of centrohelids into two taxa: Pterocystida and Panacanthocystida, which includes both Acanthocystida and the genus Yogsothoth.[2][1]

Classification edit

The modern classification of centrohelids, as of 2019:[2][1]

  • Centroplasthelida Febvre‐Chevalier & Febvre 1984 [=Centrohelea Kühn 1926 sensu Cavalier‐Smith in Yabuki et al. 2012; Centroheliozoa Dürrschmidt & Patterson 1987]
    • Pterocystida Cavalier‐Smith and von der Heyden 2007, emend. Shɨshkin and Zlatogursky 2018
      • Raphidista Shɨshkin & Zlatogursky 2018
        • Choanocystidae Cavalier-Smith & von der Heyden 2007
          • Choanocystis Penard 1904 non Cognetti 1918
        • Raphidiophryidae Mikrjukov 1996 emend. Cavalier-Smith & von der Heyden 2007
      • Pterista Shɨshkin & Zlatogursky 2018
        • Oxnerellidae Cavalier-Smith & Chao 2012
        • Pterocystidae Cavalier-Smith & von der Heyden 2007
          • Chlamydaster Rainer 1968
          • Pseudoraphidocystis Mikrjukov 1997 [Pseudoraphidiocystis (sic)]
          • Pseudoraphidiophrys Mikrjukov 1997
          • Pterocystis Siemensma & Roijackers 1988 non Lohmann 1904
          • Raineriophrys Mikrjukov 2001 [Rainierophrys (sic); Raineria Mikrjukov 1999 non Osswald 1928 non de Notaris 1838; Echinocystis Mikrjukov1997 non Haeckel 1896 non Bhatia & Chatterjee 1925 non Torrey & Gray 1840 non Gregory 1897]
        • Heterophryidae Poche 1913
          • Heterophrys Archer 1869
          • Parasphaerastrum Mikrjukov 1996
          • Sphaerastrum Greeff 1873
    • Panacanthocystida Shɨshkin & Zlatogursky 2018
      • Chthonida Shɨshkin & Zlatogursky 2018
      • Acanthocystida Cavalier-Smith 2011
        • Marophryina Cavalier-Smith 2011
          • Marophryidae Cavalier-Smith & von der Heyden 2007
            • Marophrys Cavalier-Smith & von der Heyden 2007
        • Chalarothoracina Hertwig & Lesser 1874 stat n. Cavalier-Smith 2011
          • Raphidocystidae Zlatogursky in Zlatogursky et al., 2018
            • Raphidocystis Penard 1904 [Raphidiocystis (sic) Doflein 1928 ; Rhaphidocystis (sic)]
          • Acanthocystidae Claus 1874 emend. Cavalier-Smith & von der Heyden 2007
            • Acanthocystis Carter 1863 non Kuehner 1926 non Bather 1889 non Haeckel 1896 nomen nudum
    • Incertae sedis Centroplasthelida:
      • Parasphaerastrum Mikrjukov 1996
      • Heteroraphidiophrys Mikrjukov & Patterson 2000[a]
      • Spiculophryidae Shɨshkin & Zlatogursky 2018
        • Spiculophrys Zlatogursky 2015

Notes edit

  1. ^ Heteroraphidiophrys, mentioned by Mikrjukov in 2002, was never formally introduced and needs to be avoided; the organism designated needs to be re‐isolated, carefully studied and provided with formal description.[1]

References edit

  1. ^ a b c d e Adl SM, Bass D, Lane CE, Lukeš J, Schoch CL, Smirnov A, Agatha S, Berney C, Brown MW, Burki F, Cárdenas P, Čepička I, Chistyakova L, del Campo J, Dunthorn M, Edvardsen B, Eglit Y, Guillou L, Hampl V, Heiss AA, Hoppenrath M, James TY, Karnkowska A, Karpov S, Kim E, Kolisko M, Kudryavtsev A, Lahr DJG, Lara E, Le Gall L, Lynn DH, Mann DG, Massana R, Mitchell EAD, Morrow C, Park JS, Pawlowski JW, Powell MJ, Richter DJ, Rueckert S, Shadwick L, Shimano S, Spiegel FW, Torruella G, Youssef N, Zlatogursky V, Zhang Q (2019). "Revisions to the Classification, Nomenclature, and Diversity of Eukaryotes". Journal of Eukaryotic Microbiology. 66 (1): 4–119. doi:10.1111/jeu.12691. PMC 6492006. PMID 30257078.
  2. ^ a b c Shɨshkin, Yegor; Drachko, Daria; Klimov, Vladimir I.; Zlatogursky, Vasily V. (November 2018). "Yogsothoth knorrus gen. n., sp. n. and Y. carteri sp. n. (Yogsothothidae fam. n., Haptista, Centroplasthelida), with notes on evolution and systematics of centrohelids". Protist. 169 (5): 682–696. doi:10.1016/j.protis.2018.06.003.
  3. ^ Kühn, A. (1926). Morphologie der Tiere in Bildern. Heft 2: Protozoen. Teil 2. Rhizopoden. Gebrüder Borntraeger: Berlin.
  4. ^ Nikolaev SI; Berney C; Fahrni JF; et al. (May 2004). "The twilight of Heliozoa and rise of Rhizaria, an emerging supergroup of amoeboid eukaryotes". Proc. Natl. Acad. Sci. U.S.A. 101 (21): 8066–8071. doi:10.1073/pnas.0308602101. PMC 419558. PMID 15148395.
  5. ^ Cavalier-Smith T, Chao EE (April 2003). "Molecular phylogeny of centrohelid heliozoa, a novel lineage of bikont eukaryotes that arose by ciliary loss". J. Mol. Evol. 56 (4): 387–396. Bibcode:2003JMolE..56..387C. doi:10.1007/s00239-002-2409-y. PMID 12664159. S2CID 8007933.
  6. ^ Burki, F; Inagaki, Y; Bråte, J; Archibald, J.; Keeling, P.; Cavalier-Smith, T; Sakaguchi, M; Hashimoto, T; Horak, A; Kumar, S; Klaveness, D; Jakobsen, K.S; Pawlowski, J; Shalchian-Tabrizi, K (2009). "Large-scale phylogenomic analyses reveal that two enigmatic protist lineages, Telonemia and Centroheliozoa, are related to photosynthetic chromalveolates". Genome Biology and Evolution. 1: 231–238. doi:10.1093/gbe/evp022. PMC 2817417. PMID 20333193.
  7. ^ Zhao, Sen; Burki, Fabien; Bråte, Jon; Keeling, Patrick J.; Klaveness, Dag; Shalchian-Tabrizi, Kamran (2012). "Collodictyon—An Ancient Lineage in the Tree of Eukaryotes". Molecular Biology and Evolution. 29 (6): 1557–68. doi:10.1093/molbev/mss001. PMC 3351787. PMID 22319147.
  8. ^ Cavalier-Smith, Thomas; Chao, Ema E. (2012). "Oxnerella micra sp. n. (Oxnerellidae fam. n.), a Tiny Naked Centrohelid, and the Diversity and Evolution of Heliozoa". Protist. 163 (4): 574–601. doi:10.1016/j.protis.2011.12.005. PMID 22317961.

Further reading edit

  • Patterson DJ (October 1999). "The Diversity of Eukaryotes". Am. Nat. 154 (S4): S96–S124. doi:10.1086/303287. PMID 10527921. S2CID 4367158.

April 15, 2024
centrohelid, centrohelids, centroheliozoa, large, group, heliozoan, protists, they, include, both, mobile, sessile, forms, found, freshwater, marine, environments, especially, some, depth, sraphidiophrys, contractilisscientific, classificationdomain, eukaryota. The centrohelids or centroheliozoa are a large group of heliozoan protists 4 They include both mobile and sessile forms found in freshwater and marine environments especially at some depth CentrohelidsRaphidiophrys contractilisScientific classificationDomain EukaryotaClade DiaphoretickesPhylum HaptistaClass CentroplasthelidaFebvre Chevalier amp Febvre 1984 1 Orders 1 2 Pterocystida Raphidista Pterista Panacanthocystida Chthonida AcanthocystidaIncertae sedis Spiculophryidae Parasphaerastrum HeteroraphidiophrysSynonymsCentroplastiales Centrohelina Hartmann 1913 Centroheliozoa Cushman amp Jarvis 1929 sensu Durrschmidt amp Patterson 1987 Centrohelida Kuhn 1926 3 Centrohelea Kuhn 1926 stat n Cavalier Smith 1993 Contents 1 Characteristics 2 Taxonomy 2 1 History 2 2 Classification 3 Notes 4 References 5 Further readingCharacteristics edit nbsp Diagram of a centrohelid cell Individuals are unicellular and spherical usually around 30 80 mm in diameter and covered with long radial axopods narrow cellular projections that capture food and allow mobile forms to move about A few genera have no cell covering but most have a gelatinous coat holding scales and spines produced in special deposition vesicles These may be organic or siliceous and come in various shapes and sizes For instance in Raphidiophrys the coat extends along the bases of the axopods covering them with curved spicules that give them a pine treeish look and in Raphidiocystis there are both short cup shaped spicules and long tubular spicules that are only a little shorter than the axopods Some other common genera include Heterophrys Actinocystis and Oxnerella The axopods of centrohelids are supported by microtubules in a triangular hexagonal array which arise from a tripartite granule called the centroplast at the center of the cell Axopods with a similar array occur in gymnosphaerids which have traditionally been considered centrohelids though sometimes in a separate order from the others This was questioned when it was found they have mitochondria with tubular cristae as do other heliozoa while in centrohelids the cristae are flat Although this is no longer considered a very reliable character on balance gymnosphaerids seem to be a separate group Taxonomy editHistory edit The evolutionary position of the centrohelids is not clear Structural comparisons with other groups are difficult in part because no flagella occur among centrohelids and genetic studies have been more or less inconclusive Cavalier Smith has suggested they may be related to the Rhizaria 5 but for the most part they are left with uncertain relations to other groups A 2009 paper suggests that they may be related to the cryptophytes and haptophytes see Cryptomonads haptophytes assemblage 6 They are currently classified as Hacrobia under the Plants HC clade although some research studies have found evidence against the monophyly of this group 7 Centrohelids were previously divided into two orders with contrasting scale morphology and ultrastructure Pterocystida and Acanthocystida 8 Posterior molecular studies of 2018 have rearranged the classification of centrohelids into two taxa Pterocystida and Panacanthocystida which includes both Acanthocystida and the genus Yogsothoth 2 1 Classification edit The modern classification of centrohelids as of 2019 2 1 Centroplasthelida Febvre Chevalier amp Febvre 1984 Centrohelea Kuhn 1926 sensu Cavalier Smith in Yabuki et al 2012 Centroheliozoa Durrschmidt amp Patterson 1987 Pterocystida Cavalier Smith and von der Heyden 2007 emend Shɨshkin and Zlatogursky 2018 Raphidista Shɨshkin amp Zlatogursky 2018 Choanocystidae Cavalier Smith amp von der Heyden 2007 Choanocystis Penard 1904 non Cognetti 1918 Raphidiophryidae Mikrjukov 1996 emend Cavalier Smith amp von der Heyden 2007 Raphidiophrys Archer 1867 Raphidiaphrys sic Greeff 1869 Pterista Shɨshkin amp Zlatogursky 2018 Oxnerellidae Cavalier Smith amp Chao 2012 Oxnerella Dobell 1917 Pterocystidae Cavalier Smith amp von der Heyden 2007 Chlamydaster Rainer 1968 Pseudoraphidocystis Mikrjukov 1997 Pseudoraphidiocystis sic Pseudoraphidiophrys Mikrjukov 1997 Pterocystis Siemensma amp Roijackers 1988 non Lohmann 1904 Raineriophrys Mikrjukov 2001 Rainierophrys sic Raineria Mikrjukov 1999 non Osswald 1928 non de Notaris 1838 Echinocystis Mikrjukov1997 non Haeckel 1896 non Bhatia amp Chatterjee 1925 non Torrey amp Gray 1840 non Gregory 1897 Heterophryidae Poche 1913 Heterophrys Archer 1869 Parasphaerastrum Mikrjukov 1996 Sphaerastrum Greeff 1873 Panacanthocystida Shɨshkin amp Zlatogursky 2018 Chthonida Shɨshkin amp Zlatogursky 2018 Yogsothothina Shɨshkin amp Zlatogursky 2018 Yogsothothidae Shɨshkin amp Zlatogursky 2018 Yogsothoth Shɨshkin amp Zlatogursky 2018 Acanthocystida Cavalier Smith 2011 Marophryina Cavalier Smith 2011 Marophryidae Cavalier Smith amp von der Heyden 2007 Marophrys Cavalier Smith amp von der Heyden 2007 Chalarothoracina Hertwig amp Lesser 1874 stat n Cavalier Smith 2011 Raphidocystidae Zlatogursky in Zlatogursky et al 2018 Raphidocystis Penard 1904 Raphidiocystis sic Doflein 1928 Rhaphidocystis sic Acanthocystidae Claus 1874 emend Cavalier Smith amp von der Heyden 2007 Acanthocystis Carter 1863 non Kuehner 1926 non Bather 1889 non Haeckel 1896 nomen nudum Incertae sedis Centroplasthelida Parasphaerastrum Mikrjukov 1996 Heteroraphidiophrys Mikrjukov amp Patterson 2000 a Spiculophryidae Shɨshkin amp Zlatogursky 2018 Spiculophrys Zlatogursky 2015Notes edit Heteroraphidiophrys mentioned by Mikrjukov in 2002 was never formally introduced and needs to be avoided the organism designated needs to be re isolated carefully studied and provided with formal description 1 References edit a b c d e Adl SM Bass D Lane CE Lukes J Schoch CL Smirnov A Agatha S Berney C Brown MW Burki F Cardenas P Cepicka I Chistyakova L del Campo J Dunthorn M Edvardsen B Eglit Y Guillou L Hampl V Heiss AA Hoppenrath M James TY Karnkowska A Karpov S Kim E Kolisko M Kudryavtsev A Lahr DJG Lara E Le Gall L Lynn DH Mann DG Massana R Mitchell EAD Morrow C Park JS Pawlowski JW Powell MJ Richter DJ Rueckert S Shadwick L Shimano S Spiegel FW Torruella G Youssef N Zlatogursky V Zhang Q 2019 Revisions to the Classification Nomenclature and Diversity of Eukaryotes Journal of Eukaryotic Microbiology 66 1 4 119 doi 10 1111 jeu 12691 PMC 6492006 PMID 30257078 a b c Shɨshkin Yegor Drachko Daria Klimov Vladimir I Zlatogursky Vasily V November 2018 Yogsothoth knorrus gen n sp n and Y carteri sp n Yogsothothidae fam n Haptista Centroplasthelida with notes on evolution and systematics of centrohelids Protist 169 5 682 696 doi 10 1016 j protis 2018 06 003 Kuhn A 1926 Morphologie der Tiere in Bildern Heft 2 Protozoen Teil 2 Rhizopoden Gebruder Borntraeger Berlin Nikolaev SI Berney C Fahrni JF et al May 2004 The twilight of Heliozoa and rise of Rhizaria an emerging supergroup of amoeboid eukaryotes Proc Natl Acad Sci U S A 101 21 8066 8071 doi 10 1073 pnas 0308602101 PMC 419558 PMID 15148395 Cavalier Smith T Chao EE April 2003 Molecular phylogeny of centrohelid heliozoa a novel lineage of bikont eukaryotes that arose by ciliary loss J Mol Evol 56 4 387 396 Bibcode 2003JMolE 56 387C doi 10 1007 s00239 002 2409 y PMID 12664159 S2CID 8007933 Burki F Inagaki Y Brate J Archibald J Keeling P Cavalier Smith T Sakaguchi M Hashimoto T Horak A Kumar S Klaveness D Jakobsen K S Pawlowski J Shalchian Tabrizi K 2009 Large scale phylogenomic analyses reveal that two enigmatic protist lineages Telonemia and Centroheliozoa are related to photosynthetic chromalveolates Genome Biology and Evolution 1 231 238 doi 10 1093 gbe evp022 PMC 2817417 PMID 20333193 Zhao Sen Burki Fabien Brate Jon Keeling Patrick J Klaveness Dag Shalchian Tabrizi Kamran 2012 Collodictyon An Ancient Lineage in the Tree of Eukaryotes Molecular Biology and Evolution 29 6 1557 68 doi 10 1093 molbev mss001 PMC 3351787 PMID 22319147 Cavalier Smith Thomas Chao Ema E 2012 Oxnerella micra sp n Oxnerellidae fam n a Tiny Naked Centrohelid and the Diversity and Evolution of Heliozoa Protist 163 4 574 601 doi 10 1016 j protis 2011 12 005 PMID 22317961 Further reading editPatterson DJ October 1999 The Diversity of Eukaryotes Am Nat 154 S4 S96 S124 doi 10 1086 303287 PMID 10527921 S2CID 4367158 Retrieved from https en wikipedia org w index php title Centrohelid amp oldid 1196543315, wikipedia, wiki, book, books, library,

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