Prasinophyceae
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Prasinophyceae
| Prasinophyceae | |
|---|---|
| Scientific classification | |
| Domain: | Eukaryota |
| Kingdom: | Plantae |
| Division: | Chlorophyta |
| Class: | Prasinophyceae |
| Orders[1] | |
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In taxonomy, Prasinophytes are a class of the Division Chlorophyta. These are primitive eukaryotic, marine green algae.[2] Its best known genus is Ostreococcus (seen at right), which is considered to be the smallest (ca. 0.95 μm) free-living eukaryote[3] and which has been detected in marine samples around the world. Prasinophytes are thought to have low cellular complexity, that is, they are naked cells that possess single, multiple or no flagellae and contain only a single chloroplast and a single mitochondrion. They also have very small genomes for a eukaryote (about 12Mbp).
Recent studies agree that the prasinophytes are not a natural group, being highly paraphyletic. Alternative classifications of the chlorophytes have been proposed in which this class is replaced by at least six separate taxa.[4]
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Ecology
A study of photosynthetic gene-sequence diversity (rbcL) in the Gulf of Mexico indicated that Prasinophytes are particularly prevalent at the Subsurface Chlorophyll Maximum (SCM)[5] and several different ecotypes of Ostreococcus have been detected in the environment.[6] These ecotypes are distinguished by their adaptation to light intensities. O. lucimarinus is found in high-light environments and represents surface-isolated strains. RCC141 is considered low-light, because these strains were isolated from the lower euphotic zone. O. tauri was isolated from a coastal lagoon and is considered light-polyvalent. Genetic data indicates that distinct molecular differences exist between the different ecotypes that have been detected.[7]
Phylogeny
Recent studies agree that the prasinophytes are not a natural group, being highly paraphyletic.[4][8] Relationships among the groups making up the chlorophytes are not fully resolved. The cladogram produced by Becker and Marin in 2009 is shown below. The blue shaded groups are all prasinophytes. The prasinophyte species Mesostigma viride has been shown to be a member of the Streptophyta rather than the Chlorophyta, so is not included in this cladogram.[8]
| Chlorophyta |
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References
- ^ Guiry, M.D. & Guiry, G.M. (2007). "Class: Prasinophyceae taxonomy browser". AlgaeBase version 4.2 World-wide electronic publication, National University of Ireland, Galway. http://www.algaebase.org/browse/taxonomy/?id=4345. Retrieved 2007-09-23.
- ^ Sym SD, Pienaar RN (1993). "The class Prasinophyceae". Prog Phycol Res 9: 281–376.
- ^ Courties C, Vaquer A, Troussellier M, Lautier J, Chrétiennot-Dinet MJ, Neveux J, Machado C, Claustre H (1994). "Smallest eukaryotic organism". Nature 370 (6487): 255. doi:10.1038/370255a0.
- ^ a b Lewis, Louise A. & McCourt, R.M. (2004). "Green algae and the origin of land plants". Am. J. Bot. 91 (10): 1535–1556. doi:10.3732/ajb.91.10.1535. PMID 21652308
- ^ Wawrik B, Paul JH, Campbell L, Griffin D, Houchin L, Fuentes-Ortega A, Müller-Karger F (2003). "Vertical Structure of the Phytoplankton Community Associated with a Coastal Plume in the Gulf of Mexico". Marine Ecology Progress Series 251: 87–101. doi:10.3354/meps251087.
- ^ Guillou L, Eikrem W, Chrétiennot-Dinnet MJ, Le Gall F, Massana R, Romari K, Pedros-Alio C, Vaulot D (2004). "Diversity of picoplanktonic Prasinophyceae assessed by direct SSU rDNA sequencing of environmental samples and novel isolates retrieved from oceanic and coastal marine ecosystems". Protist 155 (2): 193–214. doi:10.1078/143446104774199592. PMID 15305796.
- ^ Rodríguez F, Derelle E, Guillou L, Le Gall F, Vaulot D, Moreau H (2005). "Ecotype diversity in the marine picoeukaryote Ostreococcus (Chlorophyta, Prasinophyceae)". Environmental Microbiology 7 (6): 853–859. doi:10.1111/j.1462-2920.2005.00758.x. PMID 15892704.
- ^ a b Becker, B. & Marin, B. (2009). "Streptophyte algae and the origin of embryophytes". Annals of Botany 103 (7): 999–1004. doi:10.1093/aob/mcp044. PMC 2707909. PMID 19273476. http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2707909
External links
Links to scientific references
- PubMed references for Prasinophyceae
- PubMed Central references for Prasinophyceae
- Google Scholar references for Prasinophyceae
Links to scientific databases
- NCBI taxonomy page for Prasinophyceae
- Search Tree of Life taxonomy pages for Prasinophyceae
- Search Species2000 page for Prasinophyceae
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Mentioned in
Chlorophycota
(algae – rhodophycota, euglenophycota, chromophycota, chlorophycota)
Chlorophyceae
(algae – rhodophycota, euglenophycota, chromophycota, chlorophycota)
Phytoplankton
(plant ecology)
Algae
(thallobionta)
» More