Pfiesteria piscicida

Pfiesteria piscicida
Scientific classification
Kingdom: Protista
Phylum: Dinoflagellata
Class: Dinophyceae
Order: Phytodiniales
Family: Pfiesteriaceae
Genus: Pfiesteria
Species: P. piscicida
Binomial name
Pfiesteria piscicida
Steidinger & Burkholder

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. It was called the "Cell from Hell" in many media reports.[1] The species epithet piscicida means "fish-killer".

Life cycles

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.[2] However these results have become controversial as additional research has found only a simple haplontic life cycle with no toxic amoeboid stages[3] and amoeba present on attacked fish may represent an unrelated species of protist.[1][4]

Toxicity

Pfiesteria presumably kills fish via releasing a toxin into the water to paralyze its prey. This hypothesis has been questioned as no toxin could be isolated and no toxicity was observed in some experiments. However, toxicity appears to depend on the strains and assays used.[5] Polymerase chain reaction-analyses suggested that the organism lacks the DNA for polyketide synthesis, the type of toxins associated with most toxic dinoflagellates.[6] 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 as a metal complex and free radical toxin and also have identified how the organism transforms from a non-toxic to toxic state.[7][8][9][10]

Human illness

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, U.S., at the end of September 1997, attendees agreed on clinical symptoms that characterize a new illness associated with Pfiesteria exposure. These clinical features include:

With these criteria and environmental qualifiers (e.g., 22% 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 illness in those 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 statewide 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 Pfiesteria-associated human illness 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.[11]

Notes

  1. 1 2 "Study casts doubt on Cell from Hell's role in fish kills". Retrieved 2008-01-06.
  2. ↑ Burkholder JM, Glasgow HB (1997). "Trophic controls on stage transformations of a toxic ambush-predator dinoflagellate". J. Eukaryot. Microbiol. 44 (3): 200–5. doi:10.1111/j.1550-7408.1997.tb05700.x. PMID 9183706.
  3. ↑ Litaker RW, Vandersea MW, Kibler SR, Madden VJ, Noga EJ, Tester PA (2002). "Life cycle of the heterotrophic dinoflagellate Pfiesteria piscicida (Dinophyceae)". Journal of Phycology. 38 (3): 442–463. doi:10.1046/j.1529-8817.2002.t01-1-01242.x.
  4. ↑ Peglar MT, Nerad TA, Anderson OR, Gillevet PM (2004). "Identification of amoebae implicated in the life cycle of Pfiesteria and Pfiesteria-like dinoflagellates". J. Eukaryot. Microbiol. 51 (5): 542–52. doi:10.1111/j.1550-7408.2004.tb00290.x. PMID 15537089.
  5. ↑ Burkholder JM, Gordon AS, Moeller PD, et al. (2005). "Demonstration of toxicity to fish and to mammalian cells by Pfiesteria species: comparison of assay methods and strains". Proc. Natl. Acad. Sci. U.S.A. 102 (9): 3471–6. doi:10.1073/pnas.0500168102. PMC 552923Freely accessible. PMID 15728353.
  6. ↑ Berry JP, Reece KS, Rein KS, et al. (2002). "Are Pfiesteria species toxicogenic? Evidence against production of ichthyotoxins by Pfiesteria shumwayae". Proc. Natl. Acad. Sci. U.S.A. 99 (17): 10970–5. doi:10.1073/pnas.172221699. PMC 123194Freely accessible. PMID 12163648.
  7. ↑ Moeller PD, Beauchesne KR, Huncik KM, Davis WC, Christopher SJ, Riggs-Gelasco P, Gelasco AK (2007). "Metal complexes and free radical toxins produced by Pfiesteria piscicida". Environ. Sci. Technol. 41 (4): 1166–72. doi:10.1021/es0617993. PMID 17598275.
  8. ↑ "New Pfiesteria toxin identified". Environmental News. American Chemical Society. 15 February 2007. Retrieved 18 August 2016.
  9. ↑ "Fish study backs N.C. scientist". Archived from the original on 2008-06-08. Retrieved 2008-01-06.
  10. ↑ "Pfiesteria toxin breakthrough subject of teleconference briefing". Retrieved 2008-01-06.
  11. ↑ Report on Pfiesteria and Related Harmful Blooms: Natural Resource and Human Health Concerns Congressional Research Service

 This article incorporates public domain material from the United States Government document "a report by the Congressional Research Service (CRS), part of the Library of Congress".

References

External links

This article is issued from Wikipedia - version of the 12/1/2016. The text is available under the Creative Commons Attribution/Share Alike but additional terms may apply for the media files.