Intrastrain and interstrain variability in biotransformation enzyme activities of rainbow trout (Oncorhynchus mykiss)

Abstract

We assessed the intrastrain and interstrain variability of cytochrome P450 enzyme activities and conjugation reactions of different rainbow trout (Oncorhynchus mykiss) strains. The study protocol was divided into two parts: in two separate experiments, monooxygenase (7-ethoxyresorufin O-deethylase, EROD) and conjugation (glutathione S-transferase, GST; UDP-glucuronosyl transferase, UDPGT) enzyme activities were measured from liver and kidney samples of commonly used rainbow trout breeds. In the preliminary study, the differences in the basal biotransformation enzyme activities were detected in two separately cultivated rainbow trout strains. Results indicated significant intrastrain (UDPGT, GST) and interstrain (EROD) differences in biotransformation enzyme activities. In the experimental study, corresponding enzyme activities were measured from three different rainbow trout strains exposed to beta -naphthoflavone (BNF), a polycyclic aromatic hydrocarbon (PAH) type model compound.The results revealed significant interstrain differences, especially in hepatic EROD and GST\b activities. However, UDPGT activities in the liver, as well as the measured monooxygenase and conjugation activities in the kidney, showed no notable variance between strains.The present work addresses intrastrain differences between hatcheries and highlights the need for intercalibration of rainbow trout strains used in experimental studies in aquatic toxicology.