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Euglena viridis

Euglena viridis is a single-celled species of euglenoid, a type of microalgae. It is one of the oldest-known species of Euglena, and was first seen by Antonie van Leeuwenhoek in 1764.[1] It is found in freshwater habitats worldwide.[2]

Euglena viridis, along with other Euglena species, are well-studied.[3] Cells of E. viridis have a secondary chloroplast.[4] The chloroplast is bounded by three layers of membrane without a nucleomorph.[3]

Taxonomy

Euglena viridis is one of the first Euglena species named when Ehrenberg established the genus Euglena.[3] Euglena viridis is also the type species of this genus.[2]

The whole group of Euglenozoa was originally placed in a group called Excavata. However, Excavata has been thought not monophyletic and is divided into several groups. Now, Euglenozoa is placed below a group in Discoba.[5]

Phylogeny

According to molecular evidence, phylogenetic relationships between Euglena viridis and its close relatives are as follows:[6]

E. stellata

E. tristella

E. chadefaudii

E. pseudochadefaudii

E. granulata

E. laciniata

E. pseudostellata

E. geniculata

E. splendens

E. cantabrica

E. viridis

E. pseudoviridis

E. agilis

E. gracilis

E. gymnodinioides

E. satelles

E. mutabilis

E. deses

The phylogenetic trees of the Euglena genus still have some clades with polytomy. The phylogenetic relationship of Euglena viridis with other Euglena species is still unclear until 2017.[3]  

Morphology

Euglena viridis consists of single cells with two flagella, although one flagellum is very reduced and so only one is visible under the microscope. Normally, it is 40–65 μm long, slightly bigger than other well-known Euglena species: Euglena gracilis.[7] The cells are narrowly or widely spindle-shaped, rounded at the anterior end and pointed at the posterior end. The cell is surrounded by pellicle, which has faint spiral striations. Each cell has a single central chloroplast which is irregular and stellate, with pyrenoids. The central area of the chloroplast has a mass of paramylon grains, with additional paramylon grains scattered throughout the cell. The single emergent flagellum is roughly as long as the cell , but is sometimes dropped. Cells have a single, reddish eyespot (stigma).[8]

E. viridis typically moves with a squirming motion known as metaboly; it may also swim very rapidly. The cells can also round up to form cysts.[8]

E. viridis can be distinguished from most other Euglena species by its one axial, stellate chloroplast with a paramylon center in it. But there are still five species sharing these morphological features.[3] E. viridis differs from similar species (E. stellata, E. pseudostellata, and E. cantabrica) from lacking mucocysts (the mucocysts are only visible after staining with a dye such as neutral red), and is apparently morphologically identical to its sister species Euglena pseudoviridis.[6]

Habitat and distribution

Euglena viridis is common in bodies of water rich in organic compounds.[3] It has a cosmopolitan distribution.[2]

Euglena is considered to be the one of the most pollution-tolerant algal genera,[9] and E. viridis is an indicator of moderate to heavy pollution. E. viridis commonly forms green blooms in farmyards and sewage outfalls.[8]

Uses

Euglena viridis can be bought as a culture through some institutions[10][11] and can be maintained by replenishing it with fresh tap water and fresh leaf blades once a week.[7] Such accessibility lets it easily be used. For example, a research tests new cultivating system by cultivating Euglena viridis.[7] Additionally, E. viridis is used as teaching material in classrooms in order to demonstrate important biology concepts such as phylogenetic relationships[12] and exponential population growth.[13]

In a wastewater biodegradation system, algae can provide the oxygen that heterotrophic bacteria need for the degradation of organic matter.[14] The ability to live in polluted water bodies have let Euglena viridis be used as an oxygen producer in wastewater biodegrading systems; it has been proven that Euglena viridis can enhance biodegradation in piggery wastewater degradation system.[14]

References

  1. ^ Shin, W.; Triemer, R. E. (2003). "151 Phylogenetic Analysis of the Subgenus Euglena with Particualr Reference to the Type Species Euglena viridis (Euglenophyceae)". Journal of Phycology. 39: 52–53. Bibcode:2003JPcgy..39S..52S. doi:10.1111/j.0022-3646.2003.03906001_151.x.
  2. ^ a b c Guiry, M.D.; Guiry, G.M. "Euglena viridis (O.F.Müller) Ehrenberg 1830". AlgaeBase. University of Galway. Retrieved 2025-05-02.
  3. ^ a b c d e f Zakryś, Bożena; Milanowski, Rafał; Karnkowska, Anna (2017), Schwartzbach, Steven D.; Shigeoka, Shigeru (eds.), "Evolutionary Origin of Euglena", Euglena: Biochemistry, Cell and Molecular Biology, Advances in Experimental Medicine and Biology, vol. 979, Cham: Springer International Publishing, pp. 3–17, doi:10.1007/978-3-319-54910-1_1, ISBN 978-3-319-54910-1, PMID 28429314, retrieved 2021-12-29
  4. ^ Zimorski, Verena; Ku, Chuan; Martin, William F; Gould, Sven B (2014-12-01). "Endosymbiotic theory for organelle origins". Current Opinion in Microbiology. Growth and development: eukaryotes/ prokaryotes. 22: 38–48. doi:10.1016/j.mib.2014.09.008. ISSN 1369-5274. PMID 25306530.
  5. ^ Burki, Fabien; Roger, Andrew J.; Brown, Matthew W.; Simpson, Alastair G. B. (2020-01-01). "The New Tree of Eukaryotes". Trends in Ecology & Evolution. 35 (1): 43–55. Bibcode:2020TEcoE..35...43B. doi:10.1016/j.tree.2019.08.008. ISSN 0169-5347. PMID 31606140. S2CID 204545629.
  6. ^ a b Kosmala, Sylwia; Karnkowska-Ishikawa, Anna; Milanowski, Rafał; Kwiatowski, Jan; Zakryś, Bożena (2009). "Phylogeny and systematics of Euglena (Euglenaceae) species with axial, stellate chloroplasts based on morphological and molecular data—new taxa, emended diagnoses, and epitypifications". Journal of Phycology. 45 (2): 464–481. Bibcode:2009JPcgy..45..464K. doi:10.1111/j.1529-8817.2009.00653.x. PMID 27033825.
  7. ^ a b c Podwin, Agnieszka; Kubicki, Wojciech; Dziuban, Jan A. (2017-07-07). "Study of the behavior of Euglena viridis, Euglena gracilis and Lepadella patella cultured in all-glass microaquarium". Biomedical Microdevices. 19 (3): 63. doi:10.1007/s10544-017-0205-0. ISSN 1572-8781. PMC 5501897. PMID 28688071.
  8. ^ a b c John, David M.; Whitton, Brian A.; Brook, Alan J. (2021). The Freshwater Algal Flora of the British Isles (2 ed.). Cambridge University Press. p. 896. doi:10.1017/CHOL9781108784122. ISBN 978-1-108-78412-2.
  9. ^ Palmer, C. Mervin (1969). "A Composite Rating of Algae Tolerating Organic Pollution2". Journal of Phycology. 5 (1): 78–82. doi:10.1111/j.1529-8817.1969.tb02581.x. ISSN 1529-8817. PMID 27097257. S2CID 40469470.
  10. ^ Öffentlichkeitsarbeit, Georg-August-Universität Göttingen-. "Culture Collection of Algae (SAG) - Georg-August-Universität Göttingen". www.uni-goettingen.de (in German). Retrieved 2021-12-30.
  11. ^ "Euglena viridis Ehrenberg | ATCC". www.atcc.org. Retrieved 2021-12-30.
  12. ^ Newman, Lucas; Duffus, Amanda L. J.; Lee, Cathy (2016-09-01). "Using the Free Program MEGA to Build Phylogenetic Trees from Molecular Data". The American Biology Teacher. 78 (7): 608–612. doi:10.1525/abt.2016.78.7.608. ISSN 0002-7685. S2CID 89555924.
  13. ^ Anggraini, R.; Somakim; Hapizah (February 2019). "Students' understanding of logarithms using the growth of Euglena viridis context". Journal of Physics: Conference Series. 1166 (1): 012037. Bibcode:2019JPhCS1166a2037A. doi:10.1088/1742-6596/1166/1/012037. ISSN 1742-6596. S2CID 92221946.
  14. ^ a b Godos, Ignacio de; Vargas, Virginia A.; Blanco, Saúl; González, María C. García; Soto, Roberto; García-Encina, Pedro A.; Becares, Eloy; Muñoz, Raúl (2010-07-01). "A comparative evaluation of microalgae for the degradation of piggery wastewater under photosynthetic oxygenation". Bioresource Technology. 101 (14): 5150–5158. Bibcode:2010BiTec.101.5150G. doi:10.1016/j.biortech.2010.02.010. ISSN 0960-8524. PMID 20219356.