Microcystins are cyclic peptides produced by cyanobacteria, which can be harmful to humans and animals when ingested. Eight of the (more than) 90 microcystin variants presently characterized, contain the amino acid tryptophan. The well-researched oxidation products of tryptophan; kynurenine, oxindolylalanine, and N-formylkynurenine, have been previously identified in intact polypeptides but mic...

Microcystin, a hepatotoxin that represents a serious health risk for humans and livestock, is produced by the bloom-forming cyanobacterium Microcystis aeruginosa in freshwater bodies worldwide. Here we describe the discovery of a lectin, microvirin (MVN), in M. aeruginosa PCC7806 that shares 33% identity with the potent anti-HIV protein cyanovirin-N from Nostoc ellipsosporum. Carbohydrate micro...

The cyanobacterium Microcystis sp. frequently develops water blooms consisting of organisms with different genotypes that either produce or lack the hepatotoxin microcystin. In order to monitor the development of microcystin (mcy) genotypes during the seasonal cycle of the total population, mcy genotypes were quantified by means of real-time PCR in Lake Wannsee (Berlin, Germany) from June 1999 ...

Myriophyllum aquaticum has shown potential allelopathic effects for the biocontrol of cyanobacteria and cyanotoxins. However, composition allelochemicals their biological may be influenced by seasonal changes. In this study, we investigated impact aqueous extracts M. collected in different seasons on growth Microcystis aeruginosa concentration microcystin-LR. Plant samples were extracted using ...

Bacterial degradation of toxic microcystins produced by cyanobacteria is a common phenomenon. However, our understanding of the mechanisms of these processes is rudimentary. In this paper several novel discoveries regarding the action of the enzymes of the mlr cluster responsible for microcystin biodegradation are presented using recombinant proteins. In particular, the predicted active sites o...

s & Poster presentations Fischer, A., Hoeger, S. J., Feurstein, D. J., Ernst, B., and Dietrich, D. R. (2007). Importance of organic anion transporting polypeptides (OATPs) for the toxicity of single microcystin congeners in vitro. 7th International Conference on Toxic Cyanobacteria, Rio das Pedras, Rio de Janeiro State, Brazil. Feurstein, D., Fischer, A., and Dietrich, D. (2007). In vitro toxic...

To determine the direct effects of microcystin on the fitness of herbivorous zooplankton, we experimentally added microcystin-LR to freeze-dried cells of palatable Chlorella and fed these compound-treated cells to two clones of Daphnia pulicaria that had shown differing responses to a diet containing a strain of Microcystis aeruginosa that produces microcystin. The Daphnia that performed better...