PRASINOPHYCEAE

Contents

Prasinophyceae

Ecology

References

Prasinophyceae

Prasinophytes are a class of primitive eukaryotic, chlorophyte marine algae (Sym and Pienaar, 1993). The groups most well known member is 'Ostreococcus', which is considered to be the smallest (ca. 0.95uM) free-living eukaryote (Courties et al. 1994) and has been detected in marine samples around the world. Prasinophytes are thought to have low cellular complexity i.e. they are naked cells that lack flagella and contain only a single chloroplast and a single mitochondrium. The also have very small genomes as far as eukarytoes are concerned (about 12Mbp).

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) (Wawrik et al. 2003) and several different ecotypes of ''Ostreococcus'' have been detected in the environment (Guillou et al. 2004). 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 (Rodriguez et al. 2005).

References

Sym, S.D., and Pienaar, R.N. (1993) The class Prasinophyceae. Prog Phycol Res 9: 281–376.
Courties, C., Vaquer, A., Troussellier, M., Lautier, J.,Chrétiennot-Dinet, M.J., Neveux, J., et al. (1994) Smallest eukaryotic organism. Nature 370: 255.
Guillou, L., Eikrem, W., Chrétiennot-Dinnet, M.J., Le Call, F.,Massana, R., Romari, K., et al. (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: 193–214.
Francisco Rodríguez, Evelyne Derelle, Laure Guillou, Florence Le Gall, Daniel Vaulot, Hervé Moreau. Ecotype diversity in the marine picoeukaryote Ostreococcus (Chlorophyta, Prasinophyceae) , Environmental Microbiology (2005) 7(6), 853–859.
Wawrik, B., J.H. Paul, L. Campbell, D. Griffin, L. Houchin, A. Fuentes-Ortega, and F. Müller-Karger, 2003. Vertical Structure of the Phytoplankton Community Associated with a Coastal Plume in the Gulf of Mexico. Marine Ecology Progress Series 251:87-101