Analysis of the interaction of polycyclic aromatic compounds in a model organism: integration of genotoxic and histopathological effects

• Main Author: Sofia Pereira
• Format: Article
• Language: English
• Published: Frontiers Media S.A. 2014-05-01
• Series: Frontiers in Marine Science
• Subjects: Histology; Phenanthrene; Benzo[b]fluoranthene; Carcinogenic PAH; Non-carcinogenic PAH; DNA strand breakage
• Online Access: http://journal.frontiersin.org/Journal/10.3389/conf.fmars.2014.02.00034/full

Due to their toxicity, especially their carcinogenic potential, polycyclic aromatic hydrocarbons (PAHs) are considered priority in biomonitoring programmes. Many of these compounds are listed through the European Water Framework Directive as priority pollutants. Benzo(b)fluoranthene (B[b]F), considered potentially carcinogenic, and phenanthrene (Phe), non-carcinogenic, are two common PAHs in coastal waters and own distinct proprieties that are reflected in their mechanisms of toxicity. Still, their interaction effects onto the aquatic biota remain largely unknown. This work aimed to analyze the genotoxic effects caused by the interaction of B[b]F and Phe and their relation to histopathological alterations in the liver. The model organism was the seabass Dicentrarchus labrax, an important coastal species for fisheries and aquaculture. For the purpose, fish were injected with the two compounds (5 µg/g fish ww), isolated or in mixture, and incubated for 24h. The results only revealed minor clastogenic and aneugenic alterations, determined through erythrocytic nuclear abnormalities. On the other hand, the Comet assay showed significant DNA strand breakage in the individuals injected with B[b]F and the combination of the two compounds. On the contrary, Phe failed to cause significant genotoxic effects. Significant hepatic histopathological alterations were also found in animals injected with B[b]F, relating especially to inflammation-related responses. Overall, the results indicate no significant additive effect between B[b]F and Phe, under the current experimental conditions. Nonetheless, the seabass revealed to be sensitive to exposure to B[b]F (a higher molecular weight PAH), likely due to more efficient bioactivation of the pollutant (yielded genotoxic metabolites and reactive oxygen species), when compared to Phe. It is of paramount importance to understand the long-term interaction effects between PAHs under ecologically-relevant scenarios, since PAHs, like many other toxicants, are usually present in the aquatic environment as a complex mixture of xenobiotics.