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In gilthead sea bream, flesh quality traits such as body composition and texture directly influence yield of final product and consumer preferences so they should be considered in the breeding goal. However, strategies that involve the development of selection schemes for these traits of economic interest are scarce. Taking into account these circumstances, in this study the effect of the origin of the broodstock on the major flesh quality traits was analyzed at harvest size (690 days post-hatching) and genetic parameters (heritabilities and genetic correlations) were estimated as well as their correlations with harvest weight. For this purpose, a population of farmed gilthead sea bream was obtained from three broodstock of different geographical origins along the Spanish coast [Cantabrian Sea (CAN), the Atlantic Ocean (ATL) and Mediterranean Sea (MED)]. Parental assignments between breeders and their offspring were carried out a posteriori using a microsatellite multiplex (SMsa1). In the offspring, raw flesh composition (muscular collagen, fat, moisture and protein contents) were determined ( n = 700). Textural parameters (hardness, cohesiveness and derived traits) were measured in an industry relevant number of offspring ( n = 890) for the first time in this species. The origin had an effect on muscular fat content as well as on hardness and derived textural parameters. Fish from MED showed the lowest fat percentage and those from CAN the highest values for textural parameters. Differences among origins could be explained through their different genetic backgrounds. However, the effect of the origin could be affected by environmental conditions in the initial facilities, where each origin was reared separately, and by genotype x environment interactions. Heritabilities were medium for muscular fat (0.31 ± 0.08) and moisture (0.24 ± 0.07). The genetic correlation between them was very high and negative (− 0.99 ± 0.02). Selection for harvest weight may lead to an increase in fillet fat percentage due to the genetic correlation between the two traits (0.29 ± 0.14). Hardness showed a medium heritability (0.21 ± 0.06) and an unfavourable negative genetic correlation with harvest weight (− 0.34 ± 0.14). All findings reported in this study should be relevant for the establishment of successful breeding programs in aquaculture of this species. Statement of relevance This study proves the importance of the acquisition of a stock in sea bream since the studied origins of the broodstock has an effect on muscular fat content and textural parameters. Moreover, genetic parameters are estimated for this traits which are scarce in this species. [ABSTRACT FROM AUTHOR]

Abstract: Potentiated sulfa drugs are a combination of sulfonamide and pyrimidine potentiators. They are currently used against fish bacterial pathogens in Mediterranean marine fish farming. The present work aimed studying the potential hepatotoxicity of a combination of sulfadiazine (SDZ) and trimethoprim (TMP) in gilthead sea bream juveniles after oral administration, at the recommended ratio of 5:1 (SDZ/TMP), equivalent to a dose of 30mgkg−1 fishday−1, for 10days at 19°C temperature. Electrophoresis (DIGE) technology coupled with MS was used to identify possible markers of hepatotoxicity of this treatment. The results obtained show significant changes in the expression of 41 proteins by treatment (p≤0.02). Among these proteins, 14 increased in abundance, and 27 decreased with respect to the control group. Proteins showing differential expression with respect to the control were identified by PMF and/or LC-MS/MS and database research. Proteins like apolipoprotein A-I and fatty acid binding protein (lipid metabolism and transport, and antioxidant role), phosphoglucomutase 1 (carbohydrate metabolism), elongation factor 1-alpha (protein biosynthesis and antioxidant role), mitochondrial aldehyde dehydrogenase (oxidation regulation activity and antioxidant role) and ypbc-32-D06 (aminotransferases), were differentially expressed in treated fish. These proteins have not been associated before with potentiated sulfa effect in farmed fish. However, they are frequently found differentially expressed as a characteristic cellular/tissue stress response under different experimental conditions, making difficult their use as specific biomarkers for this treatment. [Copyright &y& Elsevier]

In order to extract salt-soluble proteins, such as myofibrillar proteins, sodium chloride is added to restructured products that serve as a binding agent among fish particles. Various additives, such as microbial transglutaminase (MTGase), have been used to reduce NaCl level in restructured products to improve water holding capacity (WHC) and textural properties. The aim of this work was to study the effect of salt level in the physicochemical and mechanical properties of uncooked restructured fish products using MTGase as cold binding agent. Except adhesiveness, the mechanical properties were affected by both salt and MTGase levels (p < 0.05). Samples with regular-salt level (20 g/kg) showed higher values of hardness, springiness and chewiness than low-salt (10 g/kg) samples (p < 0.05). Expressible water ranged from 7% to 10% for low-salt samples and from 4.3% to 4.5% for regular-salt samples, a decrease of the salt level induced a decrease in the WHC. El cloruro sodico se adiciona a los productos reestructurados con el fin de extraer las proteinas solubles, como las miofibrilares, que sirven de agentes de union en la pasta de pescado. Algunos aditivos, como la transglutaminasa microbiana, han sido utilizados en productos reestructurados bajos en sal para mejorar la capacidad de retencion de agua y las propiedades texturales. En este trabajo se estudio el efecto del nivel de sal y transglutaminasa (MGTasa), sobre las propiedades mecanicas y las caracteristicas fisicoquimicas, de un producto reestructurado no cocido de dorada (Sparus arata). Las propiedades mecanicas, a excepcion de la adhesividad, presentaron valores mas altos en las muestras con un nivel regular de sal (p < 0,05). Los valores de los parametros del Analisis de Textura TPA se incrementaban de forma significativa (p < 0,05) al aumentar la MTGasa adicionada de 3 a 6 g/kg para muestras con nivel regular de sal. El agua extraible incrementaba con el nivel de MTGasa para muestras con un contenido bajo de sal indicando un descenso en la capacidad de retencion de agua. [ABSTRACT FROM AUTHOR]

The presence of organochlorine pesticides and polychlorinated biphenyls in wild and farmed gilthead sea bream (Sparus aurata) from the Western Mediterranean, Spain, is investigated. These pollutants were determined in white and red muscle and liver by gas chromatography coupled to tandem mass spectrometry. Contaminant profiles present in both wild and farmed fish tissues include DDTs, PCBs and HCB. The highest concentrations of contaminants were found in liver, and an increase in pollutant levels was observed in autumn, before spawning. This fact is explained in light of increased food intake when sea water temperatures increase. Gilthead sea bream from Western Mediterranean populations showed significantly higher concentrations of DDTs and PCBs than farmed fish from the same area. This fact is attributed to the low level of organochlorine contaminants present in fish feed supplied to the cultured fish. The diet is highlighted as an important factor in understanding differences observed in organochlorine pollutants levels of fish tissues. [Copyright &y& Elsevier]