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Telonemia

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Telonemia is a phylum of microscopic eukaryote, single-celled organisms.[3] They were formerly classified within kingdom Chromista. They are suggested to have evolutionary significance in being a possible transitional form between ecologically important heterotrophic and photosynthetic species among chromalveolates.[2]

Telonemia
Telonema rivulare by interference contrast micrography
Scientific classification Edit this classification
Domain: Eukaryota
Clade: Diaphoretickes
Clade: TSAR
Phylum: Telonemia
Shalchian-Tabrizi 2006[2]
Class: Telonemea
Cavalier-Smith 1993[1]
Order: Telonemida
Cavalier-Smith 1993[1]
Family: Telonemidae
Cavalier-Smith 1993[1]
Genera
T. rivulare by electron micrography

Although they have been studied in primarily marine environments, they have also been found in freshwater.[4][5]

Shalchian-Tabrizi et al say that 18S rDNA sequences in the phylum formed two major groups, Group 1 and 2, including T. subtilis and T. antarcticum respectively, and that these were further sub-divided into several statistically supported clades of sequences with restricted geographic distribution. Species of Telonemia are heterotrophic predators, feeding on a wide range of bacteria and pico- to nano-sized phytoplankton. Chloroplasts have not been observed in any of the investigated species.[2] By using specific PCR primers, they revealed a much larger diversity of Telonemia from environmental samples than previously uncovered by eukaryote-wide primers. They are globally distributed in marine waters and are frequently encountered in environmental clone libraries. The evolutionary origin of Telonemia was inferred from phylogenetic reconstruction of single- and concatenated sequences obtained from both cultured strains and environmental clones.[2]

Evolution

A 2009 paper places them in the SAR supergroup.[6] Phylogenomic analyses of 127 genes in 2009 placed Telonemia with Centroheliozoa in a group containing the cryptomonads and haptophytes.[7] Pawlowski identified it in 2013 as a micro-kingdom.[8] In 2019 a phylogenetic analysis placed them as sister to the SAR group.[9]

Systematics

History

The first telonemid genus, Telonema, was described by Karl Griessmann in 1913.[10] Eighty years later, in 1993, American protistologist Thomas Cavalier-Smith created a family Telonemidae, order Telonemida and class Telonemea to contain this genus of protists. Initially, this group was included within the now obsolete phylum Opalozoa, along with other unrelated groups of flagellates such as apusomonads, jakobids, cercomonads, spongomonads, katablepharids, ebriids, proteomyxids and so on. In this scheme, the class Telonemea was distinguished by the presence fo two posterior cilia of equal length (isokont cilia). It contained an additional order besides Telonemida, Nephromycida, which comprised the genus Nephromyces[1] (later treated as an apicomplexan).[11] Since 2006, they were treated as a new eukaryotic phylum Telonemia by protistologist Kamran Shalchian-Tabrizi and coauthors, on the basis of phylogenetic analyses that placed it near chromalveolate groups such as Haptista and Cryptista.[2] However, in 2015, Cavalier-Smith and coauthors rejected their treatment as an independent phylum and transferred Telonemea to the phylum Cryptista, under the obsolete subphylum Corbihelia. This subphylum included other protists with a pharyngeal basket or radiating axopodia[12] such as Picomonas (later classified as a separate phylum Picozoa closely related to red algae)[13] and Microheliella (now proposed as the sister group to Cryptista).[14] In addition, they added a new telonemid genus, Lateronema.[12] Numerous phylogenetic analyses in the following years solidified the position of Telonemia as the sister clade to the SAR supergroup, both collectively composing the TSAR clade,[9] which lead Cavalier-Smith to finally consider Telonemia a separate phylum in 2022.[15] In the same year, a third genus was described, Arpakorses, by protistologist Denis Victorovich Tikhonenkov and coauthors.[16]

Classification

Until 2019, only two species had been formally described,[9] although DNA sequences collected from seawater suggested there were many more species not yet described.[17] In 2022, five additional species were described along with a third new genus, bringing the total number of species to seven.[16]

References

  1. ^ a b c d Cavalier-Smith, Thomas (1993). "The Protozoan Phylum Opalozoa". The Journal of Eukaryotic Microbiology. 40 (5): 609–615. doi:10.1111/j.1550-7408.1993.tb06117.x. S2CID 84129692.
  2. ^ a b c d e Shalchian-Tabrizi, K; Eikrem, W; Klaveness, D; Vaulot, D; Minge, M.A; Le Gall, F; Romari, K; Throndsen, J; Botnen, A; Massana, R; Thomsen, H.A; Jakobsen, K.S (28 April 2006). "Telonemia, a new protist phylum with affinity to chromist lineages". Proceedings of the Royal Society B: Biological Sciences. 273 (1595): 1833–1842. doi:10.1098/rspb.2006.3515. PMC 1634789. PMID 16790418.
  3. ^ Vogt, Yngve (February 1, 2012). "Found Unknown Group of Oceanic Life Forms". Apollon.
  4. ^ Lefèvre, Emilie; Roussel, Balbine; Amblard, Christian; Sime-Ngando, Télesphore; Ibelings, Bas (11 June 2008). "The Molecular Diversity of Freshwater Picoeukaryotes Reveals High Occurrence of Putative Parasitoids in the Plankton". PLOS ONE. 3 (6): e2324. Bibcode:2008PLoSO...3.2324L. doi:10.1371/journal.pone.0002324. PMC 2396521. PMID 18545660.
  5. ^ Bråte, Jon; Klaveness, Dag; Rygh, Tellef; Jakobsen, Kjetill S; Shalchian-Tabrizi, Kamran (2010). "Telonemia-specific environmental 18S rDNA PCR reveals unknown diversity and multiple marine-freshwater colonizations". BMC Microbiology. 10 (1): 168. doi:10.1186/1471-2180-10-168. PMC 2891722. PMID 20534135.
  6. ^ Reeb, Valérie C.; Peglar, Michael T.; Yoon, Hwan Su; et al. (October 2009). "Interrelationships of chromalveolates within a broadly sampled tree of photosynthetic protists". Molecular Phylogenetics and Evolution. 53 (1): 202–211. doi:10.1016/j.ympev.2009.04.012. PMID 19398025.
  7. ^ Burki, Fabien; Inagaki, Yuji; Bråte, Jon; et al. (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.
  8. ^ Pawlowski, Jan (15 April 2013). "The new micro-kingdoms of eukaryotes". BMC Biology. 11: 40. doi:10.1186/1741-7007-11-40. PMC 3626909. PMID 23587248.
  9. ^ a b c Strassert, Jürgen F H; Jamy, Mahwash; Mylnikov, Alexander P; Tikhonenkov, Denis V; Burki, Fabien; Shapiro, Beth (April 2019). "New Phylogenomic Analysis of the Enigmatic Phylum Telonemia Further Resolves the Eukaryote Tree of Life". Molecular Biology and Evolution. 36 (4): 757–765. doi:10.1093/molbev/msz012. PMC 6844682. PMID 30668767.
  10. ^ a b Grießmann, Karl (1913). Über marine Flagellaten [About marine flagellates] (Thesis) (in German). Fischer. OCLC 638176877.
  11. ^ Muñoz-Gómez, Sergio A.; Durnin, Keira; Eme, Laura; Paight, Christopher; Lane, Christopher E.; Saffo, Mary B.; Slamovits, Claudio H. (2019). "Nephromyces Represents a Diverse and Novel Lineage of the Apicomplexa That Has Retained Apicoplasts". Genome Biology and Evolution. 11 (10): 2727–2740. doi:10.1093/gbe/evz155.
  12. ^ a b c d Cavalier-Smith, Thomas; Chao, Ema E.; Lewis, Rhodri (December 2015). "Multiple origins of Heliozoa from flagellate ancestors: New cryptist subphylum Corbihelia, superclass Corbistoma, and monophyly of Haptista, Cryptista, Hacrobia and Chromista". Molecular Phylogenetics and Evolution. 93: 331–362. doi:10.1016/j.ympev.2015.07.004. PMID 26234272.
  13. ^ Schön, Max E.; Zlatogursky, Vasily V.; Singh, Rohan P.; Poirier, Camille; Wilken, Susanne; Mathur, Varsha; Strassert, Jürgen F. H.; Pinhassi, Jarone; Worden, Alexandra Z.; Keeling, Patrick J.; Ettema, Thijs J. G.; Wideman, Jeremy G.; Burki, Fabien (2021). "Single cell genomics reveals plastid-lacking Picozoa are close relatives of red algae". Nature Communications. 12: 6651. doi:10.1038/s41467-021-26918-0.
  14. ^ Yazaki, Euki; Yabuki, Akinori; Imaizumi, Ayaka; Kume, Keitaro; Hashimoto, Tetsuo; Inagaki, Yuji (2022). "The closest lineage of Archaeplastida is revealed by phylogenomics analyses that include Microheliella maris". Open Biol. 12: 210376. doi:10.1098/rsob.210376. PMC 9006020.
  15. ^ Cavalier-Smith, Thomas (2022). "Ciliary transition zone evolution and the root of the eukaryote tree: implications for opisthokont origin and classification of kingdoms Protozoa, Plantae, and Fungi". Protoplasma. 259: 487–593. doi:10.1007/s00709-021-01665-7.
  16. ^ a b c d e f g h Tikhonenkov, Denis V.; Jamy, Mahwash; Borodina, Anastasia S.; Belyaev, Artem O.; Zagumyonnyi, Dmitry G.; Prokina, Kristina I.; Mylnikov, Alexander P.; Burki, Fabien; Karpov, Sergey A. (2022). "On the origin of TSAR: morphology, diversity and phylogeny of Telonemia". Open Biology. 12 (3). The Royal Society. doi:10.1098/rsob.210325. ISSN 2046-2441. PMC 8924772. PMID 35291881.
  17. ^ Shalchian-Tabrizi, K; Kauserud, H; Massana, R; Klaveness, D; Jakobsen, KS (18 April 2007). "Analysis of Environmental 18S Ribosomal RNA Sequences reveals Unknown Diversity of the Cosmopolitan Phylum Telonemia". Protist. 158 (2): 173–180. doi:10.1016/j.protis.2006.10.003. PMID 17196879.
  18. ^ Klaveness, Dag; Shalchian-Tabrizi, Kamran; Thomsen, Helge Abildhauge; Eikrem, Wenche; Jakobsen, Kjetill S. (2005). "Telonema antarcticum sp. nov., a common marine phagotrophic flagellate". International Journal of Systematic and Evolutionary Microbiology. 55. The Microbiology Society: 2595–2604. doi:10.1099/ijs.0.63652-0.
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