Honors Theses

Date of Award

Spring 5-2-2021

Document Type

Undergraduate Thesis



First Advisor

Kristine Willett

Second Advisor

Josh Bloomekatz

Third Advisor

Deborah Gochfeld

Relational Format



Benzo[a]pyrene (BaP) is a polycyclic aromatic hydrocarbon that is linked to negative reproductive and developmental effects in humans and animals. Because BaP is carcinogenic, and its continued presence in the environment allows it to be inhaled and ingested, better understanding of the effects of BaP is needed. To determine the behavioral effects of BaP exposure, zebrafish were used as a model. Wild-type zebrafish (5D) underwent two separate 21-day dietary exposures to 2.5 and 25 μg BaP/g fish to compare how BaP exposure affects locomotor activity. Following the dietary exposure, fish were mated to obtain and raise the F1 generation to 4 or 7 mpf (months post fertilization) to determine multigenerational effects of BaP on behavior. BaP is a ligand for the aryl hydrocarbon receptor (AHR in humans; Ahr in fish), which, in turn, mediates some of BaP’s adverse outcomes (e.g., metabolic activation of a DNA reactive intermediate). Previous research has suggested that not all of BaP-mediated developmental defects are Ahr-dependent. To isolate the Ahr-dependent adverse outcomes, Ahr2OSU1 zebrafish, which lack Ahr2, were exposed to 25 μg BaP/g fish to compare responses in Ahr null versus wild-type animals. Behavior in the open field test was analyzed to measure locomotor activity and assess anxiety-like behavior. In the F0 5D strain, no significant behavioral effects of dietary BaP exposure were observed. Adult F1 female offspring of parents exposed to 25 µg BaP/g fish had a significant increase in both distance traveled and time spent mobile when compared to controls. F1 behavioral effects were not significantly different in males or when only one parental sex was exposed. Open field behaviors were not significantly different between control 4 mpf 5D and 4 mpf Ahr-null zebrafish. However, in the F0 Ahr2OSU1 strain, total distanced traveled was significantly decreased in males, but not females, following BaP exposure. The F0 Ahr2OSU1 fish did not reproduce, so F1 assessments could not be done. Overall, our results suggest that BaP behavioral impacts are sex-dependent and persistent in F1 adults, and behavioral changes in controls, as well as behavioral changes due to BaP, are not Ahr-dependent.

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Creative Commons Attribution 4.0 International License
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