Modeling Fetal Alcohol Spectrum Disorders in Zebrafish to Characterize the Impact of an Adverse Embryonic Environment on Adult Social Behavior

The scope of our lab is to understand how genes interact with brain development to influence behavior. In our lab, we use zebrafish to understand how an environmental factor like alcohol exposure during development lead to changes in a zebrafish's genes, and therefore influence brain development and leading to changes in behavior. Our overall goal is to understand whether a person's genetic profile makes them more or less likely to be affected by embryonic alcohol exposure. So in our field, we are currently using automated tracking, which increases throughput, and we're using advanced genetic editing like CRISPR technology. Pairing these two together allow us to further decipher how gene-environmental interactions lead to changes in behavior. So what we were able to show for the first time was that zebrafish could be used to model the social deficits that are associated with fetal alcohol spectrum disorders. In the past, zebrafish were used to model the more severe outcomes of prenatal alcohol exposure. Specifically what they were used for was to look for physical defects caused by high alcohol doses for long periods of time. As a field, we didn't know whether zebrafish could be used to model the social defects associated with fetal alcohol spectrum disorders. We were able to show for the first time that using a low dose of alcohol for a very short period of time leads to social defects in adult zebrafish.

[Instructor] To begin, position 1.4-liter tanks along the width of a 37-liter tank. Cover the rear and the bottom of the 37-liter tank with white corrugated plastic to enhance the contrast between the experimental fish and the background. Then position the corrugated plastic on the outer wall of the 1.4-liter tanks to enhance the contrast of the social stimulus for the experimental fish. Next, insert white corrugated plastic between the 1.4-liter and 37-liter tanks to prevent the fish from seeing each other during habitation. Position the camera at an appropriate distance to capture the length of the 37-liter tank and half of the 1.4-liter tanks. Use aquarium hood lights equipped with a 15 watt T8 full spectrum lamp to illuminate the 37-liter tank. Use an online random sequence generator to randomize all trials before conducting the behavioral assays. Then fill the 37-liter tank designated for the behavioral assay with water that matches the housing rack. Ensure the water temperature aligns with the housing rack within a 2 degree Celsius range and the water levels in all the tanks are identical. Mark 5 centimeter increments along the length of the 37-liter tank at the top and bottom to create 10 zones spanning 5 centimeters each for a 50-centimeter testing tank. Next, select two males and two females from the same cohort as the experimental fish to act as the social stimulus. Using a net, catch the 16-week-old experimental fish in the housing tank and place it in a container with fish water. Then position the experimental fish at the center of the testing arena. Check that the detection settings align with user preferences based on the chosen software before initiating the 20-minute trial. During the initial 10 minutes, maintain the opaque barrier between the 37-liter and the 1.4-liter tanks. Afterward, carefully remove the opaque barriers, allowing the experimental fish to view the social stimulus. Embryonic ethanol exposure blunted the shoaling response as these fishes failed to move close to the shoal. Control fish had a significantly stronger response to the live shoal than fish exposed to 1% alcohol. In the presence of the social stimulus, the control fish spent more time in zone 1 compared to ethanol treated fish. Embryonic ethanol exposure did not impair mobility as there is no difference between groups across zones during habituation when the social stimulus is not present. There is no difference in the amount of time fish spent in zone 1 when the social stimulus is not visible.