MP13 Aquatic Ecotoxicology
Monday, 14 November 2005: 8:00 AM - 6:30 PM in Exhibit Hall

(HEA-1117-821395) Stress Responses of Juvenile Zebrafish Exposed to -Naphthoflavone.

Heather, B¹, Lux, S¹, Weber, L¹, Janz, D^{1, 2}, ¹ Toxicology Centre, University of Saskatchewan, Saskatoon, SK, Canada² Veterinary Biomedical Science, University of Saskatchewan, Saskatoon, SK, Canada

ABSTRACT- Many ubiquitous environmental contaminants such as halogenated aromatic hydrocarbons and polycyclic aromatic hydrocarbons are aryl hydrocarbon receptor (AhR) agonists. The hypothesis of this study is that low-level exposure to AhR agonists during development will cause stress at the cellular and whole animal levels, resulting in alterations in growth, bioenergetics and gonadal development. In zebrafish (Danio rerio), exposure to toxicants such as AhR agonists during the period of sexual differentiation (20-40 days post-hatch (dph)) may interfere with normal gonadal development and gametogenesis. To test this hypothesis, juvenile zebrafish were exposed aqueously to -naphthoflavone (BNF) (0.001 mg/L, 0.01 mg/L, or 0.1 mg/L), an AhR agonist, or vehicle control (DMSO; 0.1% v/v) from 10 to 40 dph. The specific objectives of this research were to determine the potential effects of BNF exposure on bioenergetics, HSP70 expression and histopathology in juvenile zebrafish collected at 20, 30 and 40 dph. At 40 dph, mean fish length was significantly decreased in the high dose group (0.1 mg BNF/L) compared to the control group. Weight-at-length was significantly increased in the high dose group at 40 dph compared to the control group. Further work will focus on relating the observed changes in growth with bioenergetics (whole body RNA/DNA ratio, protein and triglycerides), whole body HSP70 expression, and gonadal histopathology and cell death.

Key words: zebrafish, aryl hydrocarbon receptor, gametogenesis, bioenergetics