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Light Intensity Selected for Larval Zebrafish Behavioral Assay May Influence Ability to Detect Chemically Mediated Effects
Citation:
Hill, B., D. Hunter, K. Jarema, Z. Rowson, B. Knapp, J. Olin, AND S. Padilla. Light Intensity Selected for Larval Zebrafish Behavioral Assay May Influence Ability to Detect Chemically Mediated Effects. Society of Environmental Toxicology and Chemistry 43rd Annual Meeting, Pittsburgh, PA, November 13 - 17, 2022. https://doi.org/10.23645/epacomptox.21728111
Impact/Purpose:
Poster presented to the Society of Environmental Toxicology and Chemistry SETAC North America 43rd Annual Meeting November 2022. Larval zebrafish behavior is recognized as a higher throughput testing strategy to identify developmentally neurotoxic chemicals. Interpretation and comparison of these behavior data can be challenging, and the complexity is further increased by the multitude of values chosen for behavioral assay variables in the light/dark transition test. Here we focus on one variable, the light intensity of the behavior protocol, and its influence on the ability to detect chemically-induced behavioral effects. These results emphasize that reporting the light intensities of the behavior protocol is imperative to understand potential assay confounders.
Description:
The U.S. Environmental Protection Agency is evaluating new approach methods to screen and prioritize chemicals for developmental neurotoxicity. Analysis of larval zebrafish behavior is recognized as a higher throughput testing strategy to identify developmentally neurotoxic chemicals. Interpretation and comparison of behavioral data is challenging, and some of the complexity results from inconsistent approaches (e.g. chorion status, age at time of behavior testing, and presence/absence of chemical) in the light/dark transition test between laboratories. Here we focus on one variable, the light phase intensity of the behavior protocol, and its influence on the ability to detect chemically induced behavioral effects. Six days post fertilization, normally developed zebrafish larvae were acutely exposed to a chemical previously shown to induce hypoactivity and then their behavior was assessed in a light/dark transition assay. Testing consisted of two different phases: forty minutes of a light phase at either 335 or 3,500 lux light intensity, followed by forty minutes of a dark phase (12 lux light intensity). The control (i.e., untreated) larvae generally had higher activity under the higher light phase intensity (3,500 lux), particularly in the light phase. While there was an overall significant difference in the activity patterns between the two light phase intensities, the chemical effects were comparable: all concentrations were different from the control independent of the light phase intensity used for the light/dark transition test. Despite testing with two markedly different light phase intensities, the same conclusion can be drawn. Here we sought to answer the question of whether a lower light phase intensity impedes the ability to detect chemically induced behavioral effects. We found there to be a baseline control difference using the two light phase intensities selected, but with the one chemical that was tested, we were still able to detect a difference in behavioral toxicity in both scenarios. Regardless of the results with this specific test chemical, it’s important to measure and report the light intensity used in order to develop more globally harmonized protocols. This abstract does not reflect US EPA policy.
URLs/Downloads:
DOI: Light Intensity Selected for Larval Zebrafish Behavioral Assay May Influence Ability to Detect Chemically Mediated Effects
HILL_SETAC NA 2022 POSTER_NEW TEMPLATE_10.28.22.PDF (PDF, NA pp, 2521.978 KB, about PDF)