Benzo(a)anthracene and benzo(a)pyrene exposure in the aquatic plant Fontinalis antipyretica: Uptake, elimination and the responses of biotransformation and antioxidant enzymes

Abstract

The exposure-effect relationship of benzo(a)anthracene (BaA) and benzo(a)pyrene (BaP), two potential environmental carcinogens, were evaluated in aquatic plants. The relationship was studied simultaneously by determining the BaA and BaP uptake/elimination and the responses of biotransformation and antioxidant enzymes to such exposures in the aquatic plant, Fontinalis antipyretica. The uptake of BaA and BaP by the plant was initially rapid followed by a slow phase. The concentrations of the compounds in plant reached a near steady state by the end of 168 hours of exposure. In general, the elimination of BaA and BaP from plant tissue was slow. The elimination of the compounds became even slower after the initial 24 or 48 hours of exposure for BaP or BaA, respectively. An overall increase was observed in the enzyme activities of antioxidant and conjugation systems in plants following exposure to BaA or BaP for 168 hours in either light or dark. The enzymes appeared to respond to BaP exposure more sensitively than to that of BaA. The effects on the enzyme activities were more apparent in the presence of light. Total glutathione content was higher in plants exposed to BaP than in controls. Darkness hindered the biosynthesis of glutathione in all the groups.