Estrogen receptor and multixenobiotic resistance genes in freshwater fish and snails: identification and expression analysis after pharmaceutical exposure

Sammanfattning: Pharmaceuticals are today released into aquatic environments where they can interfere with organisms' biological processes.The general research objective was to analyze how aquatic freshwater organisms are affected by exposure to pharmaceuticals that are categorized by the EU as potential risk factors to the environment (i.e., 17α-Ethinylestradiol (EE2) and diclofenac). The main aim of this thesis was to analyze the unkown mechanistic actions of EE2 and non-steroidal anti-inflammatory drugs (NSAIDs, such as diclofenac) on estrogen receptor (er) genes or multixenobiotic resistance (mxr) genes in common freshwater snails and fish. I identified several new molecular EE2 targets in freshwater wildlife such as the estrogen receptor (er) gene in female Bithynia tentaculata, the er in Radix balthica, and the estrogen receptor (esr1, esr2a and esr2b) genes in Rutilus rutilus. I also identified new molecular NSAID targets in a PLHC-1 fish liver model such as the p-glycoprotein (pgp) gene and multidrug-resistant protein 2 (mrp2) gene (after combined exposure to diclofenac and naproxen). By profiling gene expression responses, I have added to the currently limited knowledge on the mechanistic activities of pharmaceutical compounds in exposed aquatic organisms.