Glaucophyte
From Wikivisual
| Glaucophyta | |
|---|---|
| 220px | |
| Glaucocystis sp. | |
| Scientific classification | |
| Domain: | Eukaryota |
| (unranked): | Archaeplastida |
| Phylum: | Glaucophyta Skuja, 1954 |
| Class: | Glaucophyceae Bohlin, 1901 |
| Order: | Glaucocystales Bessey, 1907 |
| Family: | Glaucocystaceae G. S. West, 1904 |
| Possible genera | |
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The glaucophytes, also known as glaucocystophytes or glaucocystids, are a small group of freshwater microscopic algae.<ref name="keeling">Patrick J. Keeling (2004). "Diversity and evolutionary history of plastids and their hosts". American Journal of Botany 91: 1481–1493. doi:10.3732/ajb.91.10.1481. http://www.amjbot.org/cgi/content/full/91/10/1481.</ref> Together with the red algae (Rhodophyta) and green algae plus land plants (Viridiplantae or Chloroplastida), they form the Archaeplastida. However, the relationships between the red algae, green algae and glaucophytes are unclear,<ref name="palmer">Jeffrey D. Palmer, Douglas E. Soltis & Mark W. Chase (2004). "The plant tree of life: an overview and some points of view". American Journal of Botany 91: 1437–1445. doi:10.3732/ajb.91.10.1437. http://www.amjbot.org/cgi/content/full/91/10/1437.</ref> in large part due to limited study of the glaucophytes.
The glaucophytes are of interest to biologists studying the development of chloroplasts, because some studies suggest that they may be similar to the original alga type that led to green plants and red algae.<ref name="keeling" /><ref>Eunsoo Kim & Linda E. Graham (2008). "EEF2 analysis challenges the monophyly of Archaeplastida and Chromalveolata" (Free full text). PLoS ONE 3 (7): e2621. doi:10.1371/journal.pone.0002621. PMID 18612431. PMC 2440802. http://www.plosone.org/article/info:doi/10.1371/journal.pone.0002621.</ref>
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[edit] Characteristics
The chloroplasts of glaucophytes are known as cyanelles. Unlike plastids in other organisms they have a peptidoglycan layer that is believed to be a relic of the endosymbiotic origin of plastids from cyanobacteria.<ref name="keeling" /> Glaucophytes contain the photosynthetic pigment chlorophyll a.<ref name="keeling" /> Along with red algae<ref name="keeling" /> and cyanobacteria they harvest light via phycobilisomes, structures consisting largely of phycobiliproteins. The green algae and land plants have lost that pigment.[not in citation given]
Glaucophytes have mitochondria with flat cristae, and undergo open mitosis without centrioles. Motile forms have two unequal flagella, which may have fine hairs and are anchored by a multilayered system of microtubules, both of which are similar to forms found in some green algae.
[edit] Genera
There are only 13 species of glaucophytes known, none of which is particularly common in nature.<ref name="keeling" /> The three included genera are:
- Glaucocystis is non-motile, though it retains very short vestigial flagella, and has a cellulose wall.
- Cyanophora is motile and lacks a cell wall.
- Gloeochaete has both motile and non-motile stages, and has a cell wall that does not appear to be composed of cellulose.
[edit] References
[edit] External links
- Guiry, M.D.; Guiry, G.M. (2008). "Glaucophyta". AlgaeBase. World-wide electronic publication, National University of Ireland, Galway. http://www.algaebase.org/browse/taxonomy/detail/?taxonid=4301.
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