Oxidative stress as a mechanism for polycyclic aromatic hydrocarbon phototoxicity in cultured fish cells

Jan Marie Reber, Purdue University

Abstract

Photo-enhanced toxicity, or phototoxicity, is the phenomenon in which a compound or mixture of compounds is more toxic to an organism when that organism is exposed to the compound in the presence of UV light. Although certain polycyclic aromatic hydrocarbon (PAH) are known to be phototoxic to aquatic organisms, the mechanism for this process has not been previously demonstrated. Evidence for oxidative stress as a mechanism for such phototoxicity is presented here. The effects of three PAH (anthracene, fluoranthene and pyrene) on cultured zebrafish (Brachydanio rerio) embryo cells were examined. Oxyradical promoters (diethyldithiocarbamic acid (DDC), 1-chloro-2,4-dinitrobenzene (CDNB), maleic acid diethyl ester (MADE) and dl-buthionine- (S,R) -sulfoximine (BSO)) were added at sublethal levels as pretreatments or cotreatments with the three PAH phototoxicants. In separate experiments, oxyradical inhibitors (1,10-phenanthroline and Quin 2 AM) were added at sublethal levels as cotreatments with the phototoxicants. The PAH were found to be significantly more toxic in the presence of UV light (350 nm) than in cool white fluorescent light or darkness. All three of these PAH were found to be significantly more phototoxic if combined with any of the oxyradical promoters than were the PAH alone. Further, these phototoxicants were found to be significantly less toxic in combination with the oxyradical inhibitors, even in the presence of UV. From these results, we conclude that oxidative stress is an important mechanism of phototoxicity. Additionally, comparisons between IC50s for cultured ZEM-2A cells and LC50s published for fathead minnow embryos, we can conclude that cultured fish cells provide a viable alternative to whole organisms for oxidative stress and phototoxicity testing.

Degree

Ph.D.

Advisors

Spacie, Purdue University.

Subject Area

Forestry

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