Can estrogenic compounds enhance the activity of cathepsin D and cathepsin L in the mussel, Mytilus galloprovincialis?

The aim of this study was to obtain new information on two lysosomal enzymes, cathepsin D (Cat D) and cathepsin L (Cat L) in the Mediterranean mussel, Mytilus galloprovincialis, and to test in a preliminary way if Cat D and Cat L enzymatic activity can be enhanced in response to estrogenic compounds, such as nonylphenol (NP) and estradiol (E2). In addition to assay optimisation, a number of experiments were performed in order to assess Cat D natural seasonality, the effect of captivity on Cat D and Cat L activity, and the response to estrogenic compounds. Exposure experiments were conducted under static conditions; once exposed to NP (300 μg/l) and E2 (1000 μg/l) on day one, mussels were sampled after 7 and 14 days. The main registered effect was a significant increase of Cat D activity in the digestive gland, caused by both NP and E2. The results obtained provide preliminary information on Cat D and Cat L in the Mytilus galloprovincialis; furthermore the Cat D activity enhancement, caused by estrogenic compounds, provides a starting point for further studies designed to evaluate if the Cat D assay in mussels may supply indications on the presence of estrogenic compounds in the environment. [ABSTRACT FROM AUTHOR]