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Tenacibaculum maritimum is a Gram-negative bacterium that causes large losses in farmed turbot, Psetta maxima (L.). Main lesions included erosive and ulcerative skin injuries in different locations in the body of the fish. This study was set up to gain insights into the immune response of the turbot against this bacterial infection. To determine the variations in the peripheral blood leukocytes a minimum of 200 leukocytes in blood smears were counted. The presence of immunoglobulin positive (Ig(+)) cells in spleen, kidney, intestine, thymus and skin from turbot experimentally infected with T. maritimum were studied using an immunohistochemical method. In fish challenged with the bacterium the percentage of circulating granulocytes, lymphocytes and trombocytes showed significant differences at different points of sampling. Moreover, the number of Ig(+) cells significantly increased in the spleen, kidney, intestine and thymus. In the skin a strong immunoreactivity was observed in the interstitial liquid in damaged areas. The results obtained in this study indicated that the infection by T. maritimum in turbot induced an immune response that involved changes in the number of peripheral blood leukocytes and in the number and distribution of Ig(+) cells., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

This study was undertaken to identify the normal morphologic, immunohistochemical and ultrastructural features of skin of the turbot (Psetta maxima L.). In the turbot skin, three morphologically distinct layers were identified: epidermis, dermis and hypodermis. The epidermis was non-keratinizing, stratified squamous epithelium that varies in thickness from 5 to 14 cells and 60 to 100μm in size. Goblet cells were seen randomly distributed between malpighian cells in the epidermal layer. These mucous cells were mainly located in the upper third of the epidermis and displayed a spherical to elongated morphology. Dermis was divided in two well-differentiated layers, the superficial stratum laxum and the deeper stratum compactum. Hypodermis was a loose layer mainly composed by adipocytes but we could observe variable amounts of fibroblast, collagen and blood vessels. In turbot two pigmentary layers could be identified: the pigmentary layer of dermis was located between basement membrane and dermis and the pigmentary layer of hypodermis immediately above the muscular layer. Three different types of chromatophores were present: melanophores, iridophores and xanthophores. The main differences observed between groups of fish with different colouration were in the amount of melanophores and xanthophores. The purpose of this article is to provide an overview of normal cutaneous biology prior to consideration of specific cutaneous alterations and diseases in turbot., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

Polybrominated diphenyl ethers (PBDEs) have become ubiquitous environmental pollutants because of their widespread use as flame retardants in various consumer products (plastics, textiles, electronic appliances and building materials) and their long half-life. BDE-47 (2,2',4,4'-tetrabromodiphenyl ether) is the major PBDE congener detected in the environment and in animal tissues. In the present study, the histopathological effects are examined of BDE-47 on the gills, intestine and liver tissues of juvenile turbot (Psetta maxima).The specimens were exposed to two concentrations of BDE-47 (0.03 and 0.3 µg/L) for a period of 15 days. The histological changes were detected microscopically and evaluated with quantitative or semi-quantitative analyses. At the doses of BDE-47 assayed, the most common gill injuries were lamellar fusion, blood congestion and hyperplasia and hypertrophy of the epithelial and mucous cells. In the intestine of fish exposed to BDE-47, the alterations detected were hyperplasia and hypertrophy of mucous cells. Hepatic lesions in the liver of fish exposed to BDE-47 were characterized by circulatory disturbances, irregular morphology of hepatocytes, cellular and nuclear hypertrophy, and nuclear vacuolation and pyknosis. As BDE-47 is present in food and other material related to aquaculture systems, our results indicate that exposure to this pollutant could have serious consequences on health in turbot and other cultured fish., (Copyright © 2013 Elsevier Inc. All rights reserved.)