A multidisciplinary study of the extracutaneous pigment system of European sea bass (Dicentrarchus labrax L.). A possible relationship between kidney disease and dopa oxidase activity level.

Infectious diseases and breeding conditions can influence fish health status. Furthermore it is well known that human and animal health are strongly correlated. In lower vertebrates melano-macrophage centres, clusters of pigment-containing cells forming the extracutaneous pigment system, are widespread in the stroma of the haemopoietic tissue, mainly in kidney and spleen. In fishes, melano-macrophage centres play an important role in the immune response against antigenic stimulants and pathogens. Hence, they are employed as biomarker of fish health status. We have investigated this cell system in the European sea bass (Dicentrarchus labrax L.) following the enzyme activities involved in melanin biosynthesis. We have found a possible relationship between kidney disease of farmed fishes and dopa oxidase activity level, suggesting it as an indicator of kidney disease. Moreover variations of dopa oxidase activity in extracutaneous pigment system have been observed with respect to environmental temperature. At last, for the first time, using femtosecond transient absorption spectroscopy (Femto-TA), we pointed out that pigment-containing cells of fish kidney tissue present melanin pigments.

Effects of dietary yeast Saccaromyces cerevisiae on the antioxidant system in the liver of juvenile sea bass Dicentrarchus labrax.

The main goal of this work was to determine the effect of dietary live yeast Saccharomyces cerevisiae on the oxidative status of sea bass Dicentrarchus labrax juveniles. Fishes were fed on three diets: the GM group were fed a diet containing lyophilized yeast grown on grape must, the CS group were fed a diet containing lyophilized yeast grown on cornstarch, and the control group were fed a diet without yeast. The activity of the main antioxidative enzymes, superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase, glutathione S-transferase (GST), and glutathione (GSH) content, as well as lipid peroxidation, was measured in the liver of sea bass juveniles 90 days after hatching. Supplementation of the diet with S. cerevisiae significantly reduced the SOD and CAT activity, increased the GST activity, decreased the GSH content, and had no effect on lipid peroxidation. The results support the already reported radical-scavenging properties of yeast and usefulness of its employment as antiperoxidative agent in fish.

Diablo/SMAC: a novel biomarker of pollutant exposure in European flounder (Platichthys flesus).

Diablo (or SMAC) is a protein released from mitochondria following apoptotic stimuli and inhibits the actions of Inhibitors of Apoptosis (IAP) proteins. IAPs regulate the activity of caspases and NFkB, the primary executioners of apoptosis and of inflammation, respectively. Thus, Diablo is important for the regulation of cellular responses to damage. In Northern Europe, statutory governmental marine monitoring programs measure various biomarkers in flounder to indicate biological effects of pollutant exposure. More recently transcriptomic techniques have been applied in flounder to gain a more comprehensive understanding of pollutant effects, and to discover novel biomarkers. In most of these studies utilising flounder, Diablo was amongst the most highly increased transcripts identified. The aim of this study was to further examine piscine Diablo, at the gene level and mRNA level, after exposure to prototypical pollutants, and in flounder caught from polluted environments. The results show that two genes encoding Diablo exist in fish species, and in flounder one of these genes is increased in liver after exposure to polyaromatic hydrocarbons and polychlorinated biphenyls, and also in livers from fish living on contaminated estuarine sediments. Therefore, Diablo measurement has potential as a biomarker of pollutant exposure, and could indicate damaging effects of chemical contaminants.