Liver melanomacrophage centres as indicators of A tlantic bluefin tuna, T hunnus thynnus L. well‐being

Abstract

Melanomacrophage centres ( MMC s), located in different organs of non‐mammalian vertebrates, play a role in the destruction, detoxification or recycling of endogenous and exogenous materials. Cytochrome P 450 monoxygenase 1 A ( CYP 1A) is involved in xenobiotics biotransformation, and its liver expression is considered as a biomarker for detecting exposure to environmental pollutants. Atlantic bluefin tuna ( ABFT ), T hunnus thynnus L., liver samples were collected from: wild animals caught in the eastern A tlantic; juveniles reared in the central Adriatic; juveniles reared in the northern Adriatic; adults reared in the western Mediterranean. The samples were processed for basic histology, histochemistry and for CYP 1 A immunodetection. An unexpected high density of MMC s, containing ferric iron and lipofuscin–ceroids, was detected in the juveniles sampled in the northern A driatic S ea. These individuals showed also a strong anti‐ CYP 1 A immunopositivity in hepatocytes and in the epithelium of bile ducts. This study supports the utility of MMC s as biomarkers of fish ‘health status’ and gives concern for a potential contaminant accumulation in ABFT .

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