Induction of heme oxygenase in fish by heavy metals, phenylhydrazine and high lipid diets

Heme oxygenase (HO) was measured in fish liver and spleen by a coupled catalytic assay and by immunochemical analysis using an anti-mouse HO-1 antibody. In Atlantic salmon (Salmo salar) treated i.p. with cadmium, arsenite and phenylhydrazine, increased levels of HO activity and HO-cross-reacting protein were observed in liver microsomes. In the spleen, although no HO activity could be detected, increased levels of HO-cross-reacting protein were detected by western blotting. The cross-reacting protein in liver and spleen had a relative molecular weight of approx. 30 kDa, slightly lower than the mammalian counterpart. In mackerel (Scomber scombrus) fed a high lipid diet, increased levels of HO activity were observed in a continuously fed group compared with fish starved for 2 months and wild mackerel. The results indicate that HO may be developed into a diagnostic biomarker for certain heavy metals and oxidative stress in fish. This application relies on the production of fish-specific antibodies for this enzyme.