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GLERL 2007 Milestone Reports
< GLERL 2007 Milestone main page
GOAL: Ecosystem
Scientist: Dr. Juli Dyble (GLERL)
NOAA Performance Objective: Improve public health by developing a rapid method to detect the presence of toxic algae in drinking and recreational water supplies. .
Ecosystem Research Program Performance Measure: Percentage of tools, technologies, and information services that are used by NOAA partners/customers to improve ecosystem-based management.
OAR Performance Measure: Develop Technologies and Tools
NOAA Program: Ecosystem Research
Milestone: Develop genetic assay for quantifying the number of toxic Microcystis colonies.
Purpose: To rapidly identify and quantify toxin-producing Microcystis colonies in environmental water samples using a molecular-based assay.
Efforts and Results (to date): The recent resurgence in the harmful algal bloom genera Microcystis in the lower Great Lakes is a significant concern for ecosystem and human health. While all cyanobacterial blooms can be detrimental to the ecosystem (at times contributing to hypoxia), of particular concern to human health is the production of toxins. Microcystis can produce the hepatotoxin microcystin, which can result in gastrointestinal illness and skin irritation in the acute exposure and has the potential for increased liver disease and liver cancer in chronically exposed populations. Therefore, in the presence of toxic Microcystis blooms, beach managers need to know when to close beaches and utility managers when to increase water treatment to remove algal toxins from the drinking water supply. However, not all Microcystis blooms are toxic and the cost in both water treatment and lost tourism revenue if a nontoxic bloom is considered toxic calls for a rapid assay to distinguish toxic from non-toxic strains.
Toxic and nontoxic strains are morphologically indistinguishable, preventing microscopy from being a sufficient method of quantification of toxic colonies. However, there is a suite of genes that control the synthesis of microcystin (mcy operon) that can be detected using PCR based assays. Two molecular assays for the detection of Microcystis colonies capable of producing toxin have been developed based on a gene involved in the synthesis of the toxin microcystin, mcyB. The first was a multiplex PCR assay in which two genes are amplified at the same time: mcyB and a positive control. Microcystis colonies were isolated from throughout the western basin of Lake Erie in the summer of 2005 and 2006 and assayed for the presence of the mcyB gene. A second gene (ITS, internal transcribed spacer region of the 16S gene) was used as a positive control to ensure the integrity of the samples and the assay. Toxic Microcystis colonies were identified in all the near shore regions (on the western and southern coastlines) of western Lake Erie as well as around the Bass Islands. The proportion of toxic to non-toxic Microcystis colonies varied depending on location.
The second assay is a real-time PCR assay which is designed to quantify the number of mcyB genes in a given amount of DNA extracted from environmental samples. Unlike regular PCR which just detects whether or not the gene of interest is present, quantitative PCR uses a fluorescence-emitting probe that correlates to the number of gene copies present. We have completed the design of this assay for mcyB and are currently running quality control tests to ensure that the data is well standardized in comparison with Microcystis cell counts. We plan on using this assay to quantify toxic Microcystis cells in samples collected during summer 2006.
Customers This product can be used by academic, federal and state researchers and eventually could be useful for water utility and beach managers and public health officials.
Cause Factors (if milestone not met):
Milestone was met.
Revised Completion Date (if milestone not met):
Milestone was met.
Last updated: 2007-04-04 mbl