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ICCVAM Biennial Report 2018-2019

Biennial Progress Report 2018-2019 Interagency Coordinating Committee on the Validation of Alternative Methods

In Vitro Methods and Molecular Profiling to Evaluate Effects of Cyanobacteria Toxin in Fishes

Cyanobacteria, also known as blue-green algae, produce potent toxins called microcystins. During algal blooms, concentrations of microcystins can reach levels that are toxic to vertebrates and adversely affect fish and wildlife health. While acute effects of high-dose microcystin exposure have been investigated, there has been less focus on adverse effects resulting from low-dose or chronic exposure. In addition, there are few options for testing effects on non-model organisms. During 2018-2019, scientists in the U.S. Geological Survey of the DOI developed and applied methods to evaluate cellular and molecular responses to microcystins using primary tissue culture approaches. These in vitro methods include evaluation of primary hepatocytes and leukocytes from fishes that inhabit aquatic ecosystems vulnerable to harmful algal blooms. Specifically, this research focused on smallmouth bass collected from the upper Chesapeake Bay watershed. This analytical approach includes the application of in vitro exposures, image analysis-based flow cytometry, and transcriptional profiling of hepatic and immune-responsive genes using nCounter technology. These in vitro approaches, used to interrogate specific mechanistic questions in environmentally relevant fishes, minimize the use of vertebrates.