Metallothionein (MT): a good biomarker in marine sentinel species like sea bream (Sparus aurata)

This review presents an overview of the significance of the use of molecular biomarkers as diagnostic and prognostic tools for marine pollution monitoring. In order to assess the impact of highly persistent pollutants such as polychlorinated biphenyls (PCB), polychlorinated dibenzo–dioxins (PCDD), polychlorinated dibenzo–furans (PCDF), polynuclear aromatic hydrocarbons (PAH), tributyltin (TBT) and other toxic metals on the marine ecosystem a suite of biomarkers are being extensively used worldwide. Among the various types of biomarkers, like cytochrome P4501A induction, DNA integrity, and acetylcholinesterase activity,metallothionein induction represents an excellent biomarker. MTs are induced by toxic metals such as Cd, Hg, and Cu by chelation through cysteine residues and are used in both vertebrates and invertebrates as a biomarker of metal exposure. Sea bream is sentinel fish of its native sandy costal habitat as it is widely distributed throughout the entire Mediterranean Sea. Many studies, which results are further shown in this paper, has proposed metallothionein as a biomarker of heavy metal exposure in Sparus aurata. Recently MT expression profiles have been used as perfect diagnostic instruments to determine the physiological impact of aquaculture systems in S. aurata. All these knowledge could be very helpful to improve fish productivity and theaquaculture production system quality.