„Pfiesteria piscicida“ – Versionsunterschied

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==Life Cycle==
==Life Cycle==
[[Image:Lifecycle of Pfiesteria.jpg|thumb|right|200 px|The complex life cycle of ''Pfiesteria piscidica'' as published in the [[1990s]]: Red = toxic stages, yellow = possibly toxic stages, blue = passive stages]]
While some peer-reviewed research by government and university dinoflagellate experts has shown that its living cycle is extremely complex (these scientists have found at least 24 different stages, spanning from [[cyst]] to several [[amoeba]]-like forms), other peer-reviewed research by government and university [[dinoflagellate]] experts has found only a simple life cycle with no [[toxic]] amoebic stage. The original research claimed that the organism apparently moves through many different stages as environmental conditions require. However, the new research from [[2002]] claims the cycle is much simpler than previously thought, and that the true Pfiesteria is non-toxic (see external links).
Early research suggested a very complex [[Biological life cycle|life cycle]] of ''Pfiesteria piscicida'' with up to 24 different stages, spanning from [[Microbial cyst|cyst]] to several [[amoeboid]] forms with toxic [[zoospore]]s. Transformations from one stage to another depend on environmental conditions such as the availability of food.<ref name="pmid9183706">{{cite journal |author=Burkholder JM, Glasgow HB |title=Trophic controls on stage transformations of a toxic ambush-predator dinoflagellate |journal=J. Eukaryot. Microbiol. |volume=44 |issue=3 |pages=200–5 |year=1997 |pmid=9183706 |doi=}}</ref> However these results have become controversial as additional research has found only a simple [[Biological life cycle#Haplontic life cycle|haplontic life cycle]] with no [[toxic]] amoeboid stages<ref name="Litaker">{{cite journal |author=Litaker RW, Vandersea MW, Kibler SR, Madden VJ, Noga EJ, Tester PA |title=Life cycle of the heterotrophic dinoflagellate Pfiesteria piscicida (Dinophyceae) |journal=Journal of Phycology |volume=38 |issue=3 |pages=442–463 |year=2002 |pmid= |doi=10.1046/j.1529-8817.2002.t01-1-01242.x}}</ref> and amoeba present on attacked fish may represent an unrelated species of protist.<ref name="pmid15537089">{{cite journal |author=Peglar MT, Nerad TA, Anderson OR, Gillevet PM |title=Identification of amoebae implicated in the life cycle of Pfiesteria and Pfiesteria-like dinoflagellates |journal=J. Eukaryot. Microbiol. |volume=51 |issue=5 |pages=542–52 |year=2004 |pmid=15537089 |doi=}}</ref>


==Toxicity==
==Toxicity==

Version vom 7. Januar 2008, 04:38 Uhr

Systematik

Pfiesteria piscicida is a dinoflagellate species of the genus Pfiesteria that some researchers claim is responsible for many harmful algal blooms in the 1980s and 1990s on the coast of North Carolina and Maryland. The species name piscicida means "fish-killer."

Life Cycle

The complex life cycle of Pfiesteria piscidica as published in the 1990s: Red = toxic stages, yellow = possibly toxic stages, blue = passive stages

Early research suggested a very complex life cycle of Pfiesteria piscicida with up to 24 different stages, spanning from cyst to several amoeboid forms with toxic zoospores. Transformations from one stage to another depend on environmental conditions such as the availability of food.[1] However these results have become controversial as additional research has found only a simple haplontic life cycle with no toxic amoeboid stages[2] and amoeba present on attacked fish may represent an unrelated species of protist.[3]

Toxicity

Some peer-reviewed research based on advanced DNA-analyses shows that the organism lacks certain genetic structure to be capable of making the type of toxic proteins associated with typical dinoflagellates. Researchers from the NOAA National Centers for Coastal Ocean Science, the National Institute of Standards and Technology, the Medical University of South Carolina, and the College of Charleston (S.C.) have formally isolated and characterized the toxin in the estuarine dinoflagellete Pfiesteria Piscicida and also have identified how the organism transforms from a non-toxic to toxic state. The findings were published in the peer-reviewed science journal, Environmental Science and Technology, on 11 January 2007.[4]

Human Health

Very little research on the human health effects of Pfiesteria toxins has been conducted. At a multi-state workshop at the Centers for Disease Control and Prevention (CDC) in Atlanta, Georgia, at the end of September 1997, attendees agreed on clinical symptoms that characterize the adverse health consequences of exposure to Pfiesteria toxins. These clinical features include:

  • memory loss
  • confusion
  • acute skin burning (on direct contact with water); or
  • three or more of an additional set of conditions (headaches, skin rash, eye irritation, upper respiratory irritation, muscle cramps, and gastrointestinal complaints (i.e., nausea, vomiting, diarrhea, and/or abdominal cramps).

With these criteria and environmental qualifiers (e.g., 20% of a 50-fish sample, all of the same species, have lesions caused by a toxin), it is likely that Pfiesteria-related surveillance data can better track potential illnesses.

Pfiesteria toxins have been blamed for causing adverse health effects in people who have come in close contact with waters where this organism is abundant. Since June 1997, the Maryland Department of Health and Hygiene has been collecting data from Maryland physicians through a state-wide surveillance system on illnesses suspected of being caused by Pfiesteria toxin. As of late October 1997, illness was reported by 146 persons who had been exposed to diseased fish or to waters that were the site of suspected Pfiesteria activity. Many of these persons are watermen and commercial fishermen.

The strongest evidence of adverse human health effects so far comes from case studies of two research scientists who were both overcome in their North Carolina laboratory in 1993. They still complain of adverse effects on their cognitive abilities, particularly after exercising. Duke University Medical Center researchers conducted experiments on rats, which showed that the toxin appeared to slow learning but did not affect memory.[5]

References

Vorlage:Reflist Vorlage:USGovernment

External links

de:Pfiesteria

  1. Burkholder JM, Glasgow HB: Trophic controls on stage transformations of a toxic ambush-predator dinoflagellate. In: J. Eukaryot. Microbiol. 44. Jahrgang, Nr. 3, 1997, S. 200–5, PMID 9183706.
  2. Litaker RW, Vandersea MW, Kibler SR, Madden VJ, Noga EJ, Tester PA: Life cycle of the heterotrophic dinoflagellate Pfiesteria piscicida (Dinophyceae). In: Journal of Phycology. 38. Jahrgang, Nr. 3, 2002, S. 442–463, doi:10.1046/j.1529-8817.2002.t01-1-01242.x.
  3. Peglar MT, Nerad TA, Anderson OR, Gillevet PM: Identification of amoebae implicated in the life cycle of Pfiesteria and Pfiesteria-like dinoflagellates. In: J. Eukaryot. Microbiol. 51. Jahrgang, Nr. 5, 2004, S. 542–52, PMID 15537089.
  4. Peter D. R. Moeller, Kevin R. Beauchesne, Kevin M. Huncik, W. Clay Davis, Steven J. Christopher, Pamela Riggs-Gelasco, and Andrew K. Gelasco (2007): "Metal Complexes and Free Radical Toxins Produced by Pfiesteria piscicida." Environ. Sci. Technol., 41 (4), 1166 -1172. doi:10.1021/es0617993
  5. http://www.ncseonline.org/nle/crsreports/marine/mar-23.cfm Report on Pfiesteria and Related Harmful Blooms: Natural Resource and Human Health Concerns, Congressional Research Service