RESUMO
Teleosts are useful vertebrate model species for understanding copper toxicity due to the dual entry route for copper intake via the gills and intestine. In this present study, we utilized the differential display reverse transcription-polymerase chain reaction to isolate potential novel hepatic genes induced by sublethal copper exposure in the freshwater swordtail fish, Xiphophorus helleri. Full length cloning of a cDNA fragment induced by copper exposure to 1 µg/ml during 24 h resulted in the positive identification of a hepatic ribosomal protein L19 (RPL19) gene. Further characterization of this gene revealed that its transcriptional expression was dependent on dosage and time of copper exposure. This study describes for the first time the involvement of RPL19 in copper toxicity, probably as a result of increase in ribosome synthesis rate to support activities such as cellular protein translation, transcriptional activation and mRNA stabilization during sublethal copper exposure.