Assessment of the potential for mixed-function oxygenase enzyme induction in the extrahepatic tissues of cunners ( tautogolabrus adspersus) during reproduction

Abstract

One of the primary interests which have developed in aquatic toxicology over the past few years has been the use of the induction of mixed-function oxygenase (MFO) enzymes as a sensitive biochemical indicator for use in biological monitoring and assessment studies. Over 30 field trials had been reported to 1987 with fish indicating that induction may be common at various sites in the environment worldwide. 1 – 3 A number of other field trials have also been reported within the last two years. Most studies have focused on induction in liver but evidence suggests that liver tissues may be refractory to induction during reproduction. 4 We have investigated the potential for induction in extrahepatic and hepatic tissues of cunners pulsed with No. 2 fuel oil at various stages of reproduction. Both male and female fish were exposed during prespawning, early spawning and late spawning and induction was readily resolved in all tissues of both sexes during the three stages. The results on extrahepatic induction potential are of general toxicological interest and will find application in the design of future field studies.