Coccomyxa
A Microbial Biorealm page on the genus Coccomyxa
Classification
Eukaryota; Viridiplantae; Chlorophyta; Trebouxiophyceae; Trebouxiophyceae incertae sedis; Coccomyxaceae
Description and significance
Coccomyxa typically referred to as green algae are spherical to over in shape with a smooth surface, no flagellum. This species appears green under microscope, consisting of photopigments in addition to alloxanthin, diadinoxanthin, and diatoxanthin (3). These autotrophs contain two forms of chlorophyll, but are primarily aquatic. Coccomyxa are often found on wet rocky areas, along shorelines, or in dense films along the surface of ponds (4).
Particular species of Coccymyxa have been discovered to infect the gall bladder of marine fish. Polysporous plasmodia form clusters in the bile ducts and gall bladder of the host causing cholestasis, periductular fibrosis, and pericholangitis (2). The species Coccomyxa parasitica have also been discovered to inhabit several components of mussels (Mytilus galloprovincialis) including the mantle and gill filaments (3).
Coccomyxa are valuable for scientific research because this species has GC-rich mitrochondrial and plastic DNA. These GC-rich sequences are studied for phylogenetic analyses. There is also research about species with organelle DNAs biased toward G and C (4).
Genome structure
The ptDNA sequence is 175.7 kb in length with 56% noncoding DNA. The mtDNA sequence is 65.4 kb in length with 52% noncoding DNA. Both the mitrochondrial and plastid genome sequences (accession numbers in GenBank are HQ874522 and HQ693844 respectively)are both circular chomosomes. The mtDNA has 59 genes, and the ptDNA has 115 genes. The mitochondrial and plastid DNAs from the trebouxiophyte green alga Coccomyxa is GC-rich (60-70%). The GC-rich nature of the DNA is nonadaptive and is an innate genetic characteristic of the species. The nature of organelle DNAs are currently being researched for this species. The Coccomyxa organelle genomes have ∼500 nt of repeat sequence in common in both mtDNA and ptDNA, an unusual occurrence for eukaryotic species (4).
Cell structure, metabolism & life cycle
Provide a physical and biochemical description of the organism. What kind of organism is it, what does it look like, how is it built, what are its metabolic properties, how can it be identified, what is it's life cycle, &c. In other words, describe the organism from its perspective.
Ecology (including pathogenesis)
Describe its habitat, symbiosis, and contributions to environment. If it is a pathogen, how does this organism cause disease? Human, animal, plant hosts? Describe virulence factors and patient symptoms.
Coccomyxa inhabits salt and fresh water environments. The particular species Coccomyxa parasitica have been located off the coast of Newfoundland, Canada, as well as West Kattegat, a bay of the Baltic Sea. This species is a parasite, inhabiting many marine organisms including the gall bladders of fish, and various components of starfish, oysters, heart cockles, and blue mussles. C. parasitica have no flagella, and have a single set of chloroplasts, a mitonchrondria, a Golgi apparatus, and they reproduce by autosporulation. This species parasitic behavior is indicative by deformities, weight loss, and lowered reproductive rates of the blue mussels. While infections from green algae threaten marine life, blue mussels have indicated some ability to fight the parasite (3).
Green algae species are beneficial to other organisms. Salamander embryos grown in the presence of green algae showed lower mortality and higher growth rates than those grown in the dark with no algae (6). Licen species often have symbiotic relationships with Coccomyxa species. Licen-forming fungi have displayed protection for green algae against over exposure to ultraviolet radiation (7).
Interesting feature
Coccomyxa hydrodictyon is a unique species of algae which forms a "water net". This species forms a beautiful net-like sack formed by five or six cylindrical cells adjacent to each other. Hydrodictyon inhabits fresh water and it resources very rapidly, growing up to tens of centimeters in length. This species reproduces both asexually and sexually. As a result, each individual cell can develop into a new colony. When Hydrodictyon is present in large amounts, the fish, lakes, and irrigation ditches in the affected environment are harmed by these algae. Blooms of Hydrodictyon are problematic for drinking water resources, as this water is difficult to treat (5).
References
(1)http://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?mode=Info&id=41891&lvl=3&p=mapview&p=has_linkout&p=blast_url&p=genome_blast&lin=f&keep=1&srchmode=1&unlock "Coccomyxa". NCBI.
(2) http://www.ncbi.nlm.nih.gov/pubmed/17886740 Diamant A, Lipshitz A, Ucko M. "Phylogeny of Coccomyxa (Myxosporea: Myxidiidae) spp. with the description of a new species from Bathygobius cyclopterus (Gobiidae) in the northern Red Sea". NCBI.
(3) http://www.ncbi.nlm.nih.gov/pubmed/19686756. Crespo C, Rodríguez H, Segade P, Iglesias R, García-Estévez JM. "Coccomyxa sp. (chlorophyta: chlorococcales), a new pathogen in mussels (Mytilus galloprovincialis) of Vigo estuary (Galicia, NW Spain)". NCBI.
(4) http://www.microscopy-uk.org.uk/mag/indexmag.html?http://www.microscopy-uk.org.uk/mag/wimsmall/green.html. Egmond, Wim v. "Green Algae". Microscopy-UK.
(5) http://www.microscopy-uk.org.uk/mag/indexmag.html?http://www.microscopy-uk.org.uk/mag/wimsmall/green.html Parmentier, Jan. "Water Net". Microscopy-UK.
(6) http://www.jstor.org/pss/1565283 Marco a, Blaustein A. "Symbiosis with Green Algae Affects Survival and Growth of Northwestern Salamander Embryos". Journal of Herpetology. Vol.34 No. 4. pp. 617-621, 2000.
