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Верзија на датум 29. октобар 2016. у 20:22

NOAA na snimku jezera Iri oktobra 2011, tokom najgoreg cijanobakterijskog svetanja koje je jezero doživelo zadnjih decenija. Obilne kiše su povećale priliv đubriva, koji je promovisao rast bakterija koje proizvode mikrocistin.[1][2]

Mikrocistini (ili cijanoginozini) su klasa toksina[3] produced by certain freshwater cyanobacteria; primarily Microcystis aeruginosa but also other Microcystis, as well as members of the Planktothrix, Anabaena, Oscillatoria and Nostoc genera. Over 50 different microcystins have been discovered so far, of which Microcystin-LR is the most common. Chemically they are cyclic heptapeptides produced through nonribosomal peptide synthases.[4]

Mikrocistini can be produced in large quantities during algal blooms and pose a major threat to drinking and irrigation water supplies, as well as the environment at large.[5][6]

Karakteristike

Hemijska struktura mikrocistina LR

Mikrocistin-LR is the most toxic form of over 80 known toxic variants, and is also the most studied by chemists, pharmacologists, biologists, and ecologists. Microcystin-containing 'blooms' are a problem worldwide, including China, Brazil, Australia, South Africa,[7][8][9][10][11][12][13][14] the United States and much of Europe.

Microcystins contain several uncommon non-proteinogenic amino acids such as dehydroalanine derivatives and the uncommon β-amino acid ADDA. Microcystins covalently bond to and inhibit protein phosphatases PP1 and PP2A and can thus cause pansteatitis.[15]

Izlaganje

Microcystins are hepatotoxic (able to cause serious damage to the liver). Once ingested, microcystin travels to the liver, via the bile acid transport system, where most is stored; though some remains in the blood stream and may contaminate tissue.[16][17] There appears to be inadequate information to assess the carcinogenic potential of microcystins by applying EPA Guidelines for Carcinogen Risk Assessment. A few studies suggest a relationship may exist between liver and colorectral cancers and the occurrence of cyanobacteria in drinking water in China.[18][19][20][21][22][23] Evidence is, however, limited due to limited ability to accurately assess and measure exposure.

The impact of exposure to microcystin by patients with a compromised immune system is not yet fully known, but is starting to raise some concern.[24]

Vidi još

Reference

  1. ^ Michael Wines (2013-03-14). „Spring Rain, Then Foul Algae in Ailing Lake Erie”. The New York Times. 
  2. ^ Joanna M. Foster (2013-11-20). „Lake Erie is Dying Again, and Warmer Waters and Wetter Weather are to Blame”. ClimateProgress. 
  3. ^ Dawson, R.M. „the toxicology of microcystins”. Toxicon. 36 (7): 953—962. doi:10.1016/S0041-0101(97)00102-5. 
  4. ^ Ramsy Agha; Samuel Cirés; Lars Wörmer; Antonio Quesada (2013). „Limited Stability of Microcystins in Oligopeptide Compositions of Microcystis aeruginosa (Cyanobacteria): Implications in the Definition of Chemotypes”. Toxins. doi:10.3390/toxins5061089. 
  5. ^ Paerl HW, Huisman J (2009). „Climate change: a catalyst for global expansion of harmful cyanobacterial blooms”. Environmental Microbiology Reports. 1 (1): 27—37. PMID 23765717. doi:10.1111/j.1758-2229.2008.00004.x. 
  6. ^ „Increasing toxicity of algal blooms tied to nutrient enrichment and climate change”. Oregon State University. 2013-09-24. 
  7. ^ Bradshaw D, Groenewald P, Laubscher R, Nannan N, Nojilana B, Norman B, Pieterse D, Schneider M (2003). Initial Burden of Disease Estimates for South Africa, 2000 (PDF). Cape Town: South African Medical Research Council. ISBN 1-919809-64-3. 
  8. ^ Fatoki, O.S., Muyima, N.Y.O. & Lujiza, N. 2001. Situation analysis of water quality in the Umtata River Catchment. Water SA, (27) Pp 467-474.
  9. ^ Oberholster PJ, Botha AM, Grobbelaar JU (2004). „Microcystis aeruginosa: Source of toxic microcystins in drinking water”. Africa Journal of Biotechnology. 3: 159—68. 
  10. ^ Oberholster PJ, Botha AM, Cloete TE (2005). „An overview of toxic freshwater cyanobacteria in South Africa with special reference to risk, impact, and detection by molecular marker tools”. Biokemistri. 17: 57—71. doi:10.4314/biokem.v17i2.32590. 
  11. ^ Oberholster PJ, Botha AM (2007). „Use of PCR based technologies for risk assessment of a winter cyanobacterial bloom in Lake Midmar, South Africa”. African Journal of Biotechnology. 6 (15): 14—21. 
  12. ^ Oberholster, P. 2008. Parliamentary Briefing Paper on Cyanobacteria in Water Resources of South Africa. Annexure “A” of CSIR Report No. CSIR/NRE/WR/IR/2008/0079/C. Pretoria. Council for Scientific and Industrial Research (CSIR).
  13. ^ Oberholster, P.J.; Cloete, T.E.; van Ginkel, C.; Botha, A-M.; Ashton, P.J. (2008). „The use of remote sensing and molecular markers as early warning indicators of the development of cyanobacterial hyperscum crust and microcystin-producing genotypes in the hypertrophic Lake Hartebeespoort, South Africa” (PDF). Pretoria: Council for Scientific and Industrial Research. 
  14. ^ Oberholster, P.J.; Ashton, P.J. (2008). „State of the Nation Report: An Overview of the Current Status of Water Quality and Eutrophication in South African Rivers and Reservoirs” (PDF). Pretoria: Council for Scientific and Industrial Research. 
  15. ^ http://www.pwrc.usgs.gov/health/rattner/rattner_blackwaternwr.cfm[<span title="Потребан је потпун навод. (Недостаје неопходни параметар 1, месец! 2014)">потребан је пун навод]
  16. ^ Falconer, Ian R. (1998). „Algal Toxins and Human Health”. Ур.: Hrubec, Jiři. Quality and Treatment of Drinking Water II. The Handbook of Environmental Chemistry. стр. 53—82. doi:10.1007/978-3-540-68089-5_4. 
  17. ^ Falconer, I.R. 2005. Cyanobacterial Toxins of Drinking Water Supplies: Cylindrospermopsins and Microcystins. Florida: CRC Press. 279 pages.
  18. ^ Humpage AR, Hardy SJ, Moore EJ, Froscio SM, Falconer IR (2000). „Microcystins (cyanobacterial toxins) in drinking water enhance the growth of aberrant crypt foci in the mouse colon”. Journal of Toxicology and Environmental Health, Part A. 61 (3): 155—65. PMID 11036504. doi:10.1080/00984100050131305. 
  19. ^ Ito E, Kondo F, Terao K, Harada K (1997). „Neoplastic nodular formation in mouse liver induced by repeated intraperitoneal injections of microcystin-LR”. Toxicon. 35 (9): 1453—7. PMID 9403968. doi:10.1016/S0041-0101(97)00026-3. 
  20. ^ Nishiwaki-Matsushima R, Nishiwaki S, Ohta T, et al. (1991). „Structure-function relationships of microcystins, liver tumor promoters, in interaction with protein phosphatase”. Japanese Journal of Cancer Research. 82 (9): 993—6. PMID 1657848. doi:10.1111/j.1349-7006.1991.tb01933.x. 
  21. ^ Ueno Y, Nagata S, Tsutsumi T, et al. (1996). „Detection of microcystins, a blue-green algal hepatotoxin, in drinking water sampled in Haimen and Fusui, endemic areas of primary liver cancer in China, by highly sensitive immunoassay”. Carcinogenesis. 17 (6): 1317—21. PMID 8681449. doi:10.1093/carcin/17.6.1317. 
  22. ^ Yu S-Z (1989). „Drinking water and primary liver cancer”. Ур.: Z.Y. Tang; M.C. Wu; S.S. Xia. Primary Liver Cancer. New York: China Academic Publishers. стр. 30—7. ISBN 978-0-387-50228-1. 
  23. ^ Zhou L, Yu H, Chen K (2002). „Relationship between microcystin in drinking water and colorectal cancer”. Biomedical and Environmental Sciences. 15 (2): 166—71. PMID 12244757. 
  24. ^ Doyle P. (1991). The Impact of AIDS on the South African Population. AIDS in South Africa: The Demographics and Economic Implications. Centre for Health Policy, University of the Witwatersrand, Johannesburg, South Africa.

Literatura

  • National Center for Environmental Assessment. Toxicological Reviews of Cyanobacterial Toxins: Microcystins LR, RR, YR, and LA (NCEA-C-1765)

Spoljašnje veze

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