Phenanthrene and nitrite effects on juvenile sea bass, Dicentrarchus labrax, using hepatic biotransformation enzymes, biliary fluorescence, and micronuclei as biomarkers

Abstract

Aquatic organisms may absorb organic compounds mainly from water and by ingestion of contaminated food. The toxicity of such compounds may be intensified by the presence of certain inorganic compounds such as nitrite (NO₂^–). In order to evaluate the effect of phenanthrene (PHE), a polycyclic aromatic hydrocarbon, in the presence and absence of NO₂^–, juvenile sea bass, Dicentrarchus labrax L, were exposed to PHE i.p. and to NO₂^– in water, and several endpoints were measured at days 1, 3, and 6 of exposure. Sea bass exposed to PHE exhibited lower hepatic 7-ethoxyresorufin O-deethylase (EROD) activity as compared to the control group. The activity of the phase II enzyme, glutathione S-transferase (GST), was similar in all the groups of fish. The concentration of PHE metabolites, determined as fluorescent aromatic compounds, was nearly 14 times higher both in the presence and absence of NO₂^–, showing that even at low EROD activities this PAH is metabolized. The presence of micronuclei was observed to be significantly higher only in sea bass treated with PHE alone, suggesting that different PHE metabolites, without genotoxic properties, were formed in the presence of NO₂^–.