Mutagenic activation of arylamines by subcellular fractions of Chamaelea gallina clams exposed to environmental pollutants

Abstract

Biochemical measurements in the sentinel clam Chamaelea gallina have been used as biomarkers of marine pollution. In this study, S9, cytosolic fractions (CF), and microsomal fractions (MF) prepared from unexposed clams and clams exposed to model pollutants were used to activate 2-aminoanthracene (2-AA) and 2-acetylaminofluorene (AAF) to mutagens in Salmonella typhimurium strain BA149, which overexpresses O-acetyltransferase. Arylamine activation was similar with subcellular fractions from unexposed and Aroclor 1254-exposed clams, but decreased with fractions from As(III)- and Cu(II)-exposed clams. Bioactivation of arylamines by CF was higher than by MF, and higher with NADH than with NADPH as the reducing agent. alpha-Naphthoflavone inhibited AAF activation by CF and MF, but increased 2-AA activation nearly twofold. In contrast to the results with arylamine activation, benzo[a]pyrene hydroxylase (BPH) activity increased twofold in fractions from Aroclor 1254- and Cu(II)-exposed clams. Activation of 2-AA was also evaluated using S9 fractions from clams sampled at littoral sites with different pollutant levels. Compared to a reference site, lower 2-AA bioactivation and higher BPH activity were found in clams containing high levels of copper and organic contaminants, although the differences were not statistically significant. While these findings agree with the results of the model Cu(II) exposure, the effects of other pollutants cannot be ruled out. The results of the study demonstrate that arylamine activation by clams is not preferentially catalyzed by microsomal monooxygenases but by unknown cytosolic system(s), and that bioactivation of 2-AA and AAF appears to occur by different pathways.

Comparison of the use of mussels and semipermeable membrane devices for monitoring and assessment of accumulation of mutagenic pollutants in marine environment in combination with a novel microbiological mutagenicity assay

“…The first possibility is the analysis of tissues of marine organisms (Kadhim and Parry 1984). In this case, mussels are among the most often used animals, because of their biology and tendency to accumulate compounds that appear in their bodies due to the process of water filtration (Rodriguez-Ariza et al 1992;Canova et al 1998;Diaz-Mendez et al 1998;Lopez-Barea and Pueyo 1998;Rodriguez-Ortega et al 2003;Schiedek et al 2006). The second alternative is an employment of semipermeable membrane devices (reviewed by Lu et al 2002).…”