Aquatic Environmental Microbiology and Chemistry

University of Wisconsin Milwaukee, Zilber School of Public Health    



Tracking invasive algal species


Epifluorescent images of C. raciborskii from Lake Monona,WI. Cells were viewed at 630x magnification at wavelengths to view flourescence from phycocyanin pigments

Cylindrospermopsis raciborskii is a filamentous cyanobacterium most often observed in tropical or sub-tropical regions. Some strains of this organism have been shown to produce two powerful toxins, saxitoxin and cylindrospermopsin (Saker et al. 2001, Lagos et al. 1999). Both of these compounds are alkaloids exerting marked physiological affects in animals. Saxitoxin irreversibly binds to voltage-sensitive sodium channels preventing the release of neurotransmitters resulting in paralysis (Cestele et al. 2000). Cylindrospermopsin is a liver and kidney toxin whose mechanism of toxicity is less studied, but likely involves inhibition of pyrimidine synthesis and protein synthesis with possible tumor promoting effects . Observations of C. raciborskii in northern latitudes suggests that the range of known habitats of this organism is advancing northward. Physiological traits of this organism allow it to compete well with other dominant bloom- forming cyanobacteria such as Microcystis species. Whether C. raciborskii would coexist or outcompete with indigenous species is not clear. We recently detected this organism in eutrophic lakes of south central Wisconsin and are tracking its distribution across the watershed relative to other cyanobacteria species.

Relative abundance of C. raciborskii in a sediment core from Lake Wingra, WI. The cyanobacterium was detected by the APISA method. Relative abundance is given by relative fluorescent intensity of PCR amplified PC-IGS sequences at a size of 605 bp.

It is not clear when C. raciborskii first migrated to Wisconsin waters. Examinations of preserved water samples suggest it was present as far back as the 1980's. We are investigating the abundance of this organism in dated sediment cores taken from Wisconsin lakes in order to time its invasion. This data may help us to better understand environmental changes that have occurred, climate or otherwise, that led to its migration north. Prelminary evidence using APISA suggests that C. raciborskii was in Wisconsin waters by 1986 or sooner.




Saker, M. L., and B. A. Neilan. 2001. Varied diazotrophies, morphologies, and toxicities of genetically similar isolates of Cylindrospermopsis raciborskii (Nostocales, Cyanophyceae) from northern Australia. Appl. Environ. Microbiol. 67:1839-1845.

Lagos, N., H. Onodera, P. A. Zagatto, D. Andrinolo, S. M. F. Q. Azevedo, and Y. Oshima. 1999. The first evidence of paralytic shellfish toxins in the freshwater cyanobacterium Cylindrospermopsis raciborskii, isolated from Brazil. Toxicon 37:1359-1373.

Cestele, S., and W. A. Catterall. 2000. Molecular mechanisms of neurotoxin action on voltage-gated sodium channels. Biochimie 82:883-892.



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