T2 PM 'Omic' Technologies: Current and Future Applications to Environmental Toxicology (Part 2)
Tuesday, 15 November 2005: 1:50 PM - 5:30 PM in Ballroom 2

(CRU-1117-814694) The effects of polybrominated diphenylethers on neuronal gene expression in the herring gull (Larus argentatus).

Crump, D¹, Jagla, M¹, Kennedy, S¹, ¹ Canadian Wildlife Service, Environment Canada, Ottawa, Ontario, Canada

ABSTRACT- Polybrominated diphenylethers (PBDEs) are being detected at increasing levels in the environment due to their widespread usage as additive flame retardants in materials ranging from electronics and plastics to household furniture and insulation. Exponential increases in concentrations of PBDEs in herring gull egg homogenates have been reported throughout the Great Lakes however, toxicological endpoints have yet to be elucidated for this free-living avian species. Rodent-based studies suggest that PBDE exposure alters thyroid hormone synthesis and clearance as well as neurobehavioural endpoints associated with the cholinergic transmitter system. An avian, embryonic neuronal cell culture method was used to determine, in vitro, the impacts of the commercial penta-BDE mixture, Bromkal 70, on gene expression in herring gull neuronal cells. Two toxicogenomics approaches were employed to determine the molecular mechanisms of action of PBDEs. Fluorescent differential display PCR was used to identify candidate neuronal genes responsive to PBDE exposure and two real-time PCR multiplex assays were developed to quantify changes in mRNA abundance of the herring gull thyroid hormone receptors (alpha and beta) and neuronal nicotinic acetylcholine receptor. The in vitro approach represented an effective screening tool for PBDE effects and differential display PCR identified several novel PBDE-responsive genes in a species whose genome is not well characterized. The multiplex assays revealed that exposure to 1 and 3 M Bromkal 70 altered the expression of both thyroid hormone receptor alpha and neuronal nicotinic acetylcholine receptor. Thus, exposure of primary herring gull neuronal cells to a commercial PBDE mixture results in the alteration of genes associated with key hormonal and neurotransmitter pathways.

Key words: polybrominated diphenyl ethers, gene expression, neuronal cells, herring gull