AWRI Newsletter #66: July 2007

Recent increases in Harmful Algal Blooms of cyanobacteria (blue-green algae) in the Great Lakes region have caused significant concerns for human and ecosystem health.  Microcystis, a toxin-producing species of cyanobacteria, often dominates summer phytoplankton communities and can produce microcystins, a group of hepatotoxins that comprise over 200 congeners and molecular variants.  The ability to accurately measure the distribution and concentration of microcystins in the Great Lakes is a challenging analytical problem, but is essential to protect human and ecosystem health in the region.

AWRI researchers Richard Rediske, James O'Keefe, and graduate student, Janel Hagar, are working on a grant from the Michigan Department of Environmental Quality to examine cyanobacteria and their associated toxins in inland lakes.  In addition, they are collaborating with NOAA scientists, Juli Dyble and Gary Fahnenstiel, to examine ecosystem effects of cyanobacteria blooms in Lake Erie and Saginaw Bay.  Dr. Rediske's laboratory is currently using 3 methods to identify and measure cyanobacteria toxins:

·        Liquid Chromatography Tandem Mass Spectrometry (LC/MS) separates and analyzes individual microcystin congeners based on the production of characteristic molecular fragments.  The technique provides highly accurate results that can be used for human health assessments.  AWRI uses two LC/MS systems for cyanotoxin analysis: a Finnigan Navigator and a new Finnigan Surveyor MSQ.  The MSQ can measure cyanotoxins at part per trillion levels.

·        Enzyme Linked Immuno Sorbant Assay (ELISA). ELISA measures the presence of a structural feature in the microcystin molecule and serves as a screening tool for this group of toxins.  Because several of the congeners can cross react in the assay, ELISA is not as sensitive as LC/MS, and the results cannot be used for human health risk assessments.

·        Protein Phosphatase Inhibition Assay (PPIA). Microcystins inhibit protein phosphatase enzymes as an expression of hepatotoxicity.  PPIA provides a measure of total biological activity (toxicity) and can be used in conjunction with LC/MS and ELISA to determine if other congeners may be present.  The PPIA method was developed as part of Janel Hagar's Masters Thesis with assistance from Rebecca Uzarski (GVSU - Department of Biology) and Margaret Dietrich (GVSU - Department of Cell and Molecular Biology).

Future research concerning the causation and impacts of cyanobacteria blooms will require the integration of the above analytical methods with molecular techniques and more traditional ecological assessments of community composition and the chemical/physical environment.

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