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2C - Biomarkers (TUP/79) Biocomplexity of MXR related drug transporters in gills of the shore crab Carcinus maenas L. Koehler, Angela1, Einsporn, Sonja1, Bahns, Sieglinde1, 1 Alfred Wegener Institute for Polar and Marine Research, Bremerhaven, Germany ABSTRACT- Male shore crab were experimentally exposed to AAF, a known inducer of P-gp-related transmembrane drug transporters of the ABC gene family. These drug transporters function as efflux pumps and form a first line of defense mediating multixenobiotic resistance (MXR). Transport assays were performed in living gills (posterior) with Calcein AM which is a specific substrate for the P-glycoprotein transporter. AAF significantly induced enhanced transport efficiency as compared with unexposed controls. The inhibitor Verapamil prevented dye efflux in a concentration dependent manner. Crab adapted to low salinities showed a significantly higher transport activity than those adapted to seawater. Interestingly, we found that the feeding cycle dramatically influenced the dye/drug efflux of shore crab gills. 8 h after feeding, transport activity was nearly completely stopped. Gills of shore crab are involved in respiration, acid base regulation and osmoregulation. During digestion, gills must compensate increased oxygen demands of additional 45%, and excrete actively ammonia already 1 h after food intake. Thus, we conclude that gills overtake different tasks according to the physiological status of the animal. This hypothesis was supported by studies in hepatopancreas of the same individuals in which we found overexpression of P-gp related proteins during the period of reduced transport activity in gills, thus overtaking the task of protection against toxins. On the basis of these information we designed a sampling strategy for shore crab caught at fjord sites in Norway, differently contaminated by point source inputs of copper, PAHs, and organics from a kelp factory in comparison to clean reference sites. This field study had the aim to analyse whether MXR transport assays can be used in risk assessment of pollutants which inhibit the first line of defense located in cell membranes. Key words: shore crab, MXR, living cell imaging, biomarker |
