Perkinsus marinus
Perkinsus marinus | |
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Scientific classification | |
Domain: | Eukaryota |
Clade: | Diaphoretickes |
Clade: | SAR |
Clade: | Alveolata |
Phylum: | Myzozoa |
Class: | Perkinsea |
Order: | Perkinsida |
Family: | Perkinsidae |
Genus: | Perkinsus |
Species: | P. marinus
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Binomial name | |
Perkinsus marinus (Mackin, Owen & Collier) Levine 1978
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Synonyms | |
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Perkinsus marinus is a species of
The species originally was named Dermocystidium marinum by Mackin, Owen and Collier in 1950.[5]
Taxonomy
P. marinus is a protozoan of the protist superphylum Alveolata, the alveolates. Its phylum, Perkinsozoa, is a relatively new taxon positioned between the dinoflagellates and the Apicomplexa, and is probably more closely related to the former.[3] P. marinus is the type species of the genus Perkinsus, which was erected in 1978. When first identified in 1950, it was mistaken for a fungus.[6]
Description and life cycle
The protist is about 2 to 4
The most economically important host is the
Pathology
Perkinsosis or "dermo" is the disease condition of the oyster. The name "dermo" was coined when the protist was named Dermocystidium marinum, and it is still commonly used.[7] Infested cells are destroyed by the reproducing protist, and many trophozoites are released into the tissues of the host, or into its bloodstream. There, they infest more cells or are excreted or released when the host dies and disintegrates. The infected oyster becomes stressed, its tissues are pale in color, its gamete production is retarded, its growth slows, it becomes emaciated, its mantle shrivels and pulls away from the shell, and it may develop pockets of pus-like fluid.[3] Lysis of tissues and blockage of blood vessels causes fatality, but many oysters can persist up to 3 years with active infections.[7]
Distribution
The protist occurs along the North American coast from Maine to Florida to the Yucatán Peninsula of Mexico. Dermo epizootic outbreaks occurred in the Gulf of Mexico in the 1940s. Periodic outbreaks in the Chesapeake Bay have caused extensive oyster mortality. Significant disease has occurred in Delaware Bay, Long Island Sound, and other parts of the coast of the northeastern United States.[7]
Oyster farming operations have been disrupted in some areas, particularly in Mexico.[3]
Management
The prevalence of the protist and the disease are influenced by environmental factors such as temperature, salinity, and food availability to the hosts. Oysters exposed to environmental pollutants such as N-Nitrosodimethylamine, and tributyltins experience more severe disease.[3] At higher temperatures, the chemical defenses of the oyster, particularly its lysozymes, are reduced; infections are more common and more severe in the summer.[9] Warmer winter ocean temperatures also promote outbreaks.[10]
While laboratory studies of certain antibiotics have been promising, no methods of eradication are effective, so prevention is important. Oysters from populations or farms that have experienced disease should not be moved to areas without infestations, because the protist is easily introduced and transmitted. In aquaculture, efforts to locate and breed more resistant strains of oysters are ongoing.[3] Infested seed oysters should not be planted in oyster beds, and in disease-ridden areas, the oysters should be removed and the site allowed to lie fallow to reduce the protist load.[7]
See also
- Haplosporidium nelsoni (MSX)
References
- ^ a b Joseph, S., et al. (2010). The alveolate Perkinsus marinus: biological insights from EST gene discovery. BMC Genomics 11(1), 228.
- ^ Saldarriaga, J. F., et al. (2003). Multiple protein phylogenies show that Oxyrrhis marina and Perkinsus marinus are early branches of the dinoflagellate lineage. International Journal of Systematic and Evolutionary Microbiology 53(1), 355-65.
- ^ a b c d e f g h Bower, S. M. Synopsis of infectious diseases and parasites of commercially exploited shellfish: Perkinsus marinus ("dermo" disease) of oysters. Fisheries and Oceans Canada. 2011.
- ^ Perkinsus marinus Genome Report. National Center for Biotechnology Information.
- PMID 17791737.
- ^ Villalba, A., et al. (2004). Perkinsosis in molluscs: a review. Aquatic Living Resources 17(04), 411-32.
- ^ a b c d e Sunila, I. Dermo Disease. Oyster and Clam Diseases. Connecticut Department of Agriculture.
- ^ a b Petty, D. Perkinsus Infections of Bivalve Molluscs. FA178. Fisheries and Aquatic Sciences. Florida Cooperative Extension Service. University of Florida IFAS. Published 2010.
- ^ Chu, F. L. E. and J. F. La Peyre. (1993). Perkinsus marinus susceptibility and defense-related activities in eastern oysters Crassostrea virginica: temperature effects. Diseases of Aquatic Organisms 16, 223-34.
- ^ Cook, T., et al. (1998). The relationship between increasing sea-surface temperature and the northward spread of Perkinsus marinus (dermo) disease epizootics in oysters. Estuarine, Coastal and Shelf Science 46(4), 587-97.
Further reading
- Audemard, C., et al. (2004). Real-time PCR for detection and quantification of the protistan parasite Perkinsus marinus in environmental waters. Applied and Environmental Microbiology 70(11), 6611-18.