Influence of reproductive status, sex, and petroleum hydrocarbon exposure on hepatic and extrahepatic biotransformation enzymes of the cunner, Tautogolabrus adspersus

Abstract

Laboratory and field trials have validated liver mixed function oxygenase (MFO) induction as a sensitive biomonitor for petroleum hydrocarbon exposure. However, basal enzyme levels are known to vary seasonally and the usage of extra-hepatic tissues for biological monitoring has received little attention. Laboratory experiments were conducted in the summer of 1985 to determine the induction potential of ethoxyresorufin O-deethylase (EROD) in liver, kidney, gill, and heart tissues of cunners (Tautogolabrus adspersus) exposed to no. 2 fuel oil (diesel oil) during the reproductive season. Although basal levels varied, induction was readily resolved in hepatic and extrahepatic tissues of both male and female cunners during prespawning, early spawning and late spawning. The induction potential of heart (7-18 fold) was much greater than liver (4-6 fold), kidney (4-7 fold) and gill (2-5 fold). Male cunners displayed a much higher induction potential compared to females in heart EROD during prespawning (18 versus 13 fold) and early spawning (12 versus 7 fold) but no significant sex differences were observed during late spawning. Sex differences were also evident in liver and kidney tissues throughout the reproductive season, males exhibiting higher enzyme activities than females in each case. -- The potential for induction of a conjugating enzyme, glutathione S-transferase (GST), was also studied. Unlike EROD, GST was refractory to induction in all tissues of male and female cunners throughout gonad maturation/spawning. Depression of GST was observed in the heart tissue of diesel exposed males during early spawning and male liver and kidney during late spawning. -- These experiments show the feasibility of using extrahepatic as well as hepatic MFO enzymes for monitoring studies even during the reproductive season.