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Protocol light level effects on larval zebrafish behavior and the ability to detect chemical differences
Citation:
Hill, B., D. Hunter, K. Jarema, Z. Rowson, B. Knapp, J. Olin, AND S. Padilla. Protocol light level effects on larval zebrafish behavior and the ability to detect chemical differences. NC Society of Toxicology, Durham, NC, NC, October 19, 2022. https://doi.org/10.23645/epacomptox.21370524
Impact/Purpose:
Poster presented to the North Carolina Society of Toxicology Meeting October 2022. Analysis of larval zebrafish behavior is recognized as a higher throughput testing strategy to identify developmentally neurotoxic chemicals. Interpretation and comparison of behavioral data among laboratories is challenging, and some of the complexity results from inconsistent approaches. 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. 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. 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.
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 between laboratories 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. 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 at 12 lux light intensity. The control (i.e., untreated) larvae generally had more 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 is 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: Protocol light level effects on larval zebrafish behavior and the ability to detect chemical differences
B HILL NC SOT 2022 POSTER_10.13.22.PDF (PDF, NA pp, 899.107 KB, about PDF)