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Feed conversion ratio (FCR) is an important trait to target in fish breeding programs, and the aim of the present study is to underline how the genetic improvement of FCR in gilthead sea bream (Sparus aurata) drives to changes in transcriptional and behavioural patterns. Groups of fish with high (FCR+) and low (FCR-) individual FCR were established at the juvenile stage (161–315 dph) by rearing isolated fish on a restricted ration. Fish were then grouped on the basis of their individual FCR and they grew up until behavioural monitoring and gene expression analyses were done at 420 dph. The AEFishBIT datalogger (externally attached to operculum) was used for simultaneous measurements of physical activity and ventilation rates. This allowed discrimination of FCR+ and FCR- groups according to their different behaviour and energy partitioning for growth and locomotor activity. Gene expression profiling of liver and white muscle was made using customized PCR-arrays of 44 and 29 genes, respectively. Up to 15 genes were differentially expressed in liver and muscle tissues highlighting a different metabolic scope of FCR+ and FCR- fish. Hepatic gene expression profile of FCR- fish displayed a lower lipogenic activity that was concurrent with a down-regulation of markers of mitochondrial activity and oxidative stress, as well as a reallocation of body fat depots with an enhanced flux of lipids towards skeletal muscle. Muscle gene expression profile of FCR- fish matched with stimulatory and inhibitory growth signals, and an activation of energy sensors and antioxidant defence as part of the operating mechanisms for a more efficient muscle growth. These new insights contribute to phenotype the genetically mediated differences in fish FCR thanks to the combination of transcriptomic and behavioural approaches that contribute to better understand the mechanisms involved in a reliable FCR improvement of farmed gilthead sea bream.

Feed conversion ratio (FCR) is an important trait to target in fish breeding programs, and the aim of the present study is to underline how the genetic improvement of FCR in gilthead sea bream (Sparus aurata) drives to changes in transcriptional and behavioural patterns. Groups of fish with high (FCR+) and low (FCR-) individual FCR were established at the juvenile stage (161–315 dph) by rearing isolated fish on a restricted ration. Fish were then grouped on the basis of their individual FCR and they grew up until behavioural monitoring and gene expression analyses were done at 420 dph. The AEFishBIT datalogger (externally attached to operculum) was used for simultaneous measurements of physical activity and ventilation rates. This allowed discrimination of FCR+ and FCR- groups according to their different behaviour and energy partitioning for growth and locomotor activity. Gene expression profiling of liver and white muscle was made using customized PCR-arrays of 44 and 29 genes, respectively. Up to 15 genes were differentially expressed in liver and muscle tissues highlighting a different metabolic scope of FCR+ and FCR- fish. Hepatic gene expression profile of FCR- fish displayed a lower lipogenic activity that was concurrent with a down-regulation of markers of mitochondrial activity and oxidative stress, as well as a reallocation of body fat depots with an enhanced flux of lipids towards skeletal muscle. Muscle gene expression profile of FCR- fish matched with stimulatory and inhibitory growth signals, and an activation of energy sensors and antioxidant defence as part of the operating mechanisms for a more efficient muscle growth. These new insights contribute to phenotype the genetically mediated differences in fish FCR thanks to the combination of transcriptomic and behavioural approaches that contribute to better understand the mechanisms involved in a reliable FCR improvement of farmed gilthead sea bream.

Gut microbiomes of fish species consist of thousands of bacterial taxa that interact among each other, their environment, and the host. These complex networks of interactions are regulated by a diverse range of factors, yet little is known about the hierarchy of these interactions. Here, we introduce SAMBA (Structure-Learning of Aquaculture Microbiomes using a Bayesian Approach), a computational tool that uses a unified Bayesian network approach to model the network structure of fish gut microbiomes and their interactions with biotic and abiotic variables associated with typical aquaculture systems. SAMBA accepts input data on microbial abundance from 16S rRNA amplicons as well as continuous and categorical information from distinct farming conditions. From this, SAMBA can create and train a network model scenario that can be used to (i) infer information of how specific farming conditions influence the diversity of the gut microbiome or pan-microbiome, and (ii) predict how the diversity and functional profile of that microbiome would change under other variable conditions. SAMBA also allows the user to visualize, manage, edit, and export the acyclic graph of the modelled network. Our study presents examples and test results of Bayesian network scenarios created by SAMBA using data from a microbial synthetic community, and the pan-microbiome of gilthead sea bream (Sparus aurata) in different feeding trials. It is worth noting that the usage of SAMBA is not limited to aquaculture systems as it can be used for modelling microbiome–host network relationships of any vertebrate organism, including humans, in any system and/or ecosystem.

Gilthead sea bream (Sparus aurata) is considered an asymptomatic carrier for the nodavirus genotype affecting European sea bass (Dicentrarchus labrax), RGNNV. Only larvae and juveniles of sea bream have been found to be susceptible to the RGNNV/SJNNV reassortant. Nevertheless, the molecular bases of the high resistance of sea bream against RGNNV are not known, and the overall transcriptome response to the virus remains unexplored. In this work, we conducted the first RNA-Seq analysis of sea bream infected with RGNNV to elucidate the immune mechanisms involved in their resistance. Since we recently published the transcriptome response of sea bass infected with RGNNV, we wanted to take the same tissues (brain and head kidney) at the same time points (24 and 72 h postinfection) to conduct comparative analyses. Sea bream responded to RGNNV challenge with a powerful immune arsenal characterized by the high expression of a multitude of type I interferon-related genes, immune receptors and antigen presentation-related genes in both tissues. Moreover, complement-, coagulation- and angiogenesis-related genes were highly enriched in the head kidney at the earlier sampling point. Interestingly, despite the strong immune response found in the brain, inflammation seems to have been restrained, resulting in a neuroprotective scenario. While the response in sea bass was characterized by the activation of the stress axis, which could lead to immunosuppression and neuronal damage, genes involved in these processes were not modulated in sea bream. An efficient antiviral response accompanied by low inflammation and the absence of stimulation of the stress response seem to play a role in the success of sea bream in resisting RGNNV infection

The study combined the use of biometric, behavioral, physiological and external tissue damage scoring systems to better understand how high stocking densities drive schooling behavior and other adaptive features during the finishing growing phase of farmed gilthead sea bream in the Western Mediterranean. Fish were grown at three different final stocking densities (LD, 8.5 kg/m3; MD, 17 kg/m3; HD, 25 kg/m3). Water oxygen concentration varied between 5 and 6 ppm in LD fish to 3–4 ppm in HD fish with the summer rise of water temperature from 19°C to 26°C (May–July). HD fish showed a reduction of feed intake and growth rates, but they also showed a reinforced social cohesion with a well-defined endogenous swimming activity rhythm with feeding time as a main synchronization factor. The monitored decrease of the breathing/swimming activity ratio by means of the AEFishBIT data-logger also indicated a decreased energy partitioning for growth in the HD environment with a limited oxygen availability. Plasma glucose and cortisol levels increased with the rise of stocking density, and the close association of glycaemia with the expression level of antioxidant enzymes (mn-sod, gpx4, prdx5) in liver and molecular chaperones (grp170, grp75) in skeletal muscle highlighted the involvement of glucose in redox processes via rerouting in the pentose-phosphate-pathway. Other adaptive features included the depletion of oxidative metabolism that favored lipid storage rather than fatty acid oxidation to decrease the oxygen demand as last electron acceptor in the mitochondrial respiratory chain. This was coincident with the metabolic readjustment of the Gh/Igf endocrine-growth cascade that promoted the regulation of muscle growth at the local level rather than a systemic action via the liver Gh/Igf axis. Moreover, correlation analyses within HD fish displayed negative correlations of hepatic transcripts of igf1 and igf2 with the data-logger measurements of activity and respiration, whereas

The study combined the use of biometric, behavioral, physiological and external tissue damage scoring systems to better understand how high stocking densities drive schooling behavior and other adaptive features during the finishing growing phase of farmed gilthead sea bream in the Western Mediterranean. Fish were grown at three different final stocking densities (LD, 8.5 kg/m3; MD, 17 kg/m3; HD, 25 kg/m3). Water oxygen concentration varied between 5 and 6 ppm in LD fish to 3–4 ppm in HD fish with the summer rise of water temperature from 19°C to 26°C (May–July). HD fish showed a reduction of feed intake and growth rates, but they also showed a reinforced social cohesion with a well-defined endogenous swimming activity rhythm with feeding time as a main synchronization factor. The monitored decrease of the breathing/swimming activity ratio by means of the AEFishBIT data-logger also indicated a decreased energy partitioning for growth in the HD environment with a limited oxygen availability. Plasma glucose and cortisol levels increased with the rise of stocking density, and the close association of glycaemia with the expression level of antioxidant enzymes (mn-sod, gpx4, prdx5) in liver and molecular chaperones (grp170, grp75) in skeletal muscle highlighted the involvement of glucose in redox processes via rerouting in the pentose-phosphate-pathway. Other adaptive features included the depletion of oxidative metabolism that favored lipid storage rather than fatty acid oxidation to decrease the oxygen demand as last electron acceptor in the mitochondrial respiratory chain. This was coincident with the metabolic readjustment of the Gh/Igf endocrine-growth cascade that promoted the regulation of muscle growth at the local level rather than a systemic action via the liver Gh/Igf axis. Moreover, correlation analyses within HD fish displayed negative correlations of hepatic transcripts of igf1 and igf2 with the data-logger measurements of activity and respiration, whereas

The study combined the use of biometric, behavioral, physiological and external tissue damage scoring systems to better understand how high stocking densities drive schooling behavior and other adaptive features during the finishing growing phase of farmed gilthead sea bream in the Western Mediterranean. Fish were grown at three different final stocking densities (LD, 8.5 kg/m3; MD, 17 kg/m3; HD, 25 kg/m3). Water oxygen concentration varied between 5 and 6 ppm in LD fish to 3–4 ppm in HD fish with the summer rise of water temperature from 19°C to 26°C (May–July). HD fish showed a reduction of feed intake and growth rates, but they also showed a reinforced social cohesion with a well-defined endogenous swimming activity rhythm with feeding time as a main synchronization factor. The monitored decrease of the breathing/swimming activity ratio by means of the AEFishBIT data-logger also indicated a decreased energy partitioning for growth in the HD environment with a limited oxygen availability. Plasma glucose and cortisol levels increased with the rise of stocking density, and the close association of glycaemia with the expression level of antioxidant enzymes (mn-sod, gpx4, prdx5) in liver and molecular chaperones (grp170, grp75) in skeletal muscle highlighted the involvement of glucose in redox processes via rerouting in the pentose-phosphate-pathway. Other adaptive features included the depletion of oxidative metabolism that favored lipid storage rather than fatty acid oxidation to decrease the oxygen demand as last electron acceptor in the mitochondrial respiratory chain. This was coincident with the metabolic readjustment of the Gh/Igf endocrine-growth cascade that promoted the regulation of muscle growth at the local level rather than a systemic action via the liver Gh/Igf axis. Moreover, correlation analyses within HD fish displayed negative correlations of hepatic transcripts of igf1 and igf2 with the data-logger measurements of activity and respiration, whereas

The study combined the use of biometric, behavioral, physiological and external tissue damage scoring systems to better understand how high stocking densities drive schooling behavior and other adaptive features during the finishing growing phase of farmed gilthead sea bream in the Western Mediterranean. Fish were grown at three different final stocking densities (LD, 8.5 kg/m3; MD, 17 kg/m3; HD, 25 kg/m3). Water oxygen concentration varied between 5 and 6 ppm in LD fish to 3–4 ppm in HD fish with the summer rise of water temperature from 19°C to 26°C (May–July). HD fish showed a reduction of feed intake and growth rates, but they also showed a reinforced social cohesion with a well-defined endogenous swimming activity rhythm with feeding time as a main synchronization factor. The monitored decrease of the breathing/swimming activity ratio by means of the AEFishBIT data-logger also indicated a decreased energy partitioning for growth in the HD environment with a limited oxygen availability. Plasma glucose and cortisol levels increased with the rise of stocking density, and the close association of glycaemia with the expression level of antioxidant enzymes (mn-sod, gpx4, prdx5) in liver and molecular chaperones (grp170, grp75) in skeletal muscle highlighted the involvement of glucose in redox processes via rerouting in the pentose-phosphate-pathway. Other adaptive features included the depletion of oxidative metabolism that favored lipid storage rather than fatty acid oxidation to decrease the oxygen demand as last electron acceptor in the mitochondrial respiratory chain. This was coincident with the metabolic readjustment of the Gh/Igf endocrine-growth cascade that promoted the regulation of muscle growth at the local level rather than a systemic action via the liver Gh/Igf axis. Moreover, correlation analyses within HD fish displayed negative correlations of hepatic transcripts of igf1 and igf2 with the data-logger measurements of activity and respiration, whereas

The study combined the use of biometric, behavioral, physiological and external tissue damage scoring systems to better understand how high stocking densities drive schooling behavior and other adaptive features during the finishing growing phase of farmed gilthead sea bream in the Western Mediterranean. Fish were grown at three different final stocking densities (LD, 8.5 kg/m3; MD, 17 kg/m3; HD, 25 kg/m3). Water oxygen concentration varied between 5 and 6 ppm in LD fish to 3–4 ppm in HD fish with the summer rise of water temperature from 19°C to 26°C (May–July). HD fish showed a reduction of feed intake and growth rates, but they also showed a reinforced social cohesion with a well-defined endogenous swimming activity rhythm with feeding time as a main synchronization factor. The monitored decrease of the breathing/swimming activity ratio by means of the AEFishBIT data-logger also indicated a decreased energy partitioning for growth in the HD environment with a limited oxygen availability. Plasma glucose and cortisol levels increased with the rise of stocking density, and the close association of glycaemia with the expression level of antioxidant enzymes (mn-sod, gpx4, prdx5) in liver and molecular chaperones (grp170, grp75) in skeletal muscle highlighted the involvement of glucose in redox processes via rerouting in the pentose-phosphate-pathway. Other adaptive features included the depletion of oxidative metabolism that favored lipid storage rather than fatty acid oxidation to decrease the oxygen demand as last electron acceptor in the mitochondrial respiratory chain. This was coincident with the metabolic readjustment of the Gh/Igf endocrine-growth cascade that promoted the regulation of muscle growth at the local level rather than a systemic action via the liver Gh/Igf axis. Moreover, correlation analyses within HD fish displayed negative correlations of hepatic transcripts of igf1 and igf2 with the data-logger measurements of activity and respiration, whereas

Aquaculture is the fastest-growing food production sector and nowadays provides more food than extractive fishing. Studies focused on the understanding of how teleost growth is regulated are essential to improve fish production. Cysteamine (CSH) is a novel feed additive that can improve growth through the modulation of the GH/IGF axis; however, the underlying mechanisms and the interaction between tissues are not well understood. This study aimed to investigate the effects of CSH inclusion in diets at 1.65 g/kg of feed for 9 weeks and 1.65 g/kg or 3.3 g/kg for 9 weeks more, on growth performance and the GH/IGF-1 axis in plasma, liver, stomach, and white muscle in gilthead sea bream (Sparus aurata) fingerlings (1.8 ± 0.03 g) and juveniles (14.46 ± 0.68 g). Additionally, the effects of CSH stimulation in primary cultured muscle cells for 4 days on cell viability and GH/IGF axis relative gene expression were evaluated. Results showed that CSH-1.65 improved growth performance by 16% and 26.7% after 9 and 18 weeks, respectively, while CSH-3.3 improved 32.3% after 18 weeks compared to control diet (0 g/kg). However, no significant differences were found between both experimental doses. CSH reduced the plasma levels of GH after 18 weeks and increased the IGF-1 ones after 9 and 18 weeks. Gene expression analysis revealed a significant upregulation of the ghr-1, different igf-1 splice variants, igf-2 and the downregulation of the igf-1ra and b, depending on the tissue and dose. Myocytes stimulated with 200 µM of CSH showed higher cell viability and mRNA levels of ghr1, igf-1b, igf-2 and igf-1rb compared to control (0 µM) in a similar way to white muscle. Overall, CSH improves growth and modulates the GH/IGF-1 axis in vivo and in vitro toward an anabolic status through different synergic ways, revealing CSH as a feasible candidate to be included in fish feed.

The study combined the use of biometric, behavioral, physiological and external tissue damage scoring systems to better understand how high stocking densities drive schooling behavior and other adaptive features during the finishing growing phase of farmed gilthead sea bream in the Western Mediterranean. Fish were grown at three different final stocking densities (LD, 8.5 kg/m3; MD, 17 kg/m3; HD, 25 kg/m3). Water oxygen concentration varied between 5 and 6 ppm in LD fish to 3–4 ppm in HD fish with the summer rise of water temperature from 19°C to 26°C (May–July). HD fish showed a reduction of feed intake and growth rates, but they also showed a reinforced social cohesion with a well-defined endogenous swimming activity rhythm with feeding time as a main synchronization factor. The monitored decrease of the breathing/swimming activity ratio by means of the AEFishBIT data-logger also indicated a decreased energy partitioning for growth in the HD environment with a limited oxygen availability. Plasma glucose and cortisol levels increased with the rise of stocking density, and the close association of glycaemia with the expression level of antioxidant enzymes (mn-sod, gpx4, prdx5) in liver and molecular chaperones (grp170, grp75) in skeletal muscle highlighted the involvement of glucose in redox processes via rerouting in the pentose-phosphate-pathway. Other adaptive features included the depletion of oxidative metabolism that favored lipid storage rather than fatty acid oxidation to decrease the oxygen demand as last electron acceptor in the mitochondrial respiratory chain. This was coincident with the metabolic readjustment of the Gh/Igf endocrine-growth cascade that promoted the regulation of muscle growth at the local level rather than a systemic action via the liver Gh/Igf axis. Moreover, correlation analyses within HD fish displayed negative correlations of hepatic transcripts of igf1 and igf2 with the data-logger measurements of activity and respiration, whereas

Aquaculture is the fastest-growing food production sector and nowadays provides more food than extractive fishing. Studies focused on the understanding of how teleost growth is regulated are essential to improve fish production. Cysteamine (CSH) is a novel feed additive that can improve growth through the modulation of the GH/IGF axis; however, the underlying mechanisms and the interaction between tissues are not well understood. This study aimed to investigate the effects of CSH inclusion in diets at 1.65 g/kg of feed for 9 weeks and 1.65 g/kg or 3.3 g/kg for 9 weeks more, on growth performance and the GH/IGF-1 axis in plasma, liver, stomach, and white muscle in gilthead sea bream (Sparus aurata) fingerlings (1.8 ± 0.03 g) and juveniles (14.46 ± 0.68 g). Additionally, the effects of CSH stimulation in primary cultured muscle cells for 4 days on cell viability and GH/IGF axis relative gene expression were evaluated. Results showed that CSH-1.65 improved growth performance by 16% and 26.7% after 9 and 18 weeks, respectively, while CSH-3.3 improved 32.3% after 18 weeks compared to control diet (0 g/kg). However, no significant differences were found between both experimental doses. CSH reduced the plasma levels of GH after 18 weeks and increased the IGF-1 ones after 9 and 18 weeks. Gene expression analysis revealed a significant upregulation of the ghr-1, different igf-1 splice variants, igf-2 and the downregulation of the igf-1ra and b, depending on the tissue and dose. Myocytes stimulated with 200 µM of CSH showed higher cell viability and mRNA levels of ghr1, igf-1b, igf-2 and igf-1rb compared to control (0 µM) in a similar way to white muscle. Overall, CSH improves growth and modulates the GH/IGF-1 axis in vivo and in vitro toward an anabolic status through different synergic ways, revealing CSH as a feasible candidate to be included in fish feed.

The present research tested the effects of dietary nisin-producing Lactococcus lactis on growth performance, feed utilization, intestinal morphology, transcriptional response, and microbiota in gilthead sea bream (Sparus aurata). A feeding trial was conducted with fish weighting 70–90 g. Fish were tagged with passive, integrated transponders and distributed in nine 500 L tanks with 40 fish each. Fish were fed for 12 weeks with either a control (diet A) or experimental diets (diets B and C) in triplicate (3 tanks/diet). Extruded pellets of diets B and C were supplemented with a low (2 × 109 CFU/kg) and a high (5 × 109 CFU/kg) dose of probiotic, respectively. No significant differences were found between groups for the feed conversion ratio or specific growth rates. However, the final body weight of fish fed diet C was significantly higher than the control group with intermediate values for fish fed diet B. Histological analysis conducted using a semi-quantitative scoring system showed that probiotic did not alter the morphology of the intestine and did not trigger inflammation. With regard to the transcriptomic response, a customized PCR array layout was designed to simultaneously profile a panel of 44 selected genes. Significant differences in the expression of key genes involved in innate and acquired immunity were detected between fish fed probiotic and control diets. To analyze the microbiota associated to the feeds and the gut autochthonous microbial communities, we used the Illumina MiSeq platform for sequencing the 16S rRNA gene and a metagenomics pipeline based on VSEARCH and RDP databases. The analysis of gut microbiota revealed a lack of colonization of the probiotic in the host’s intestinal mucosa. However, probiotic did modulate the fish gut microbiota, confirming that colonization is not always necessary to induce host modification. In fact, diets B and C were enriched with Actinomycetales, as compared to diet A, which instead showed a higher percentage

The aquaculture sector has experienced rapid and important growth with the subsequent increase of feeding and nutritional issues for sustaining this activity, mainly related to the use of high quality, safe and environmentally friendly feed ingredients. The use of additives in aquafeeds has proven to be a suitable option to improve different productive indicators in farmed fish. In the present study, the effect of adding the GHRP-6 peptide, a ghrelin analog, to a commercial diet of gilthead sea bream (Sparus aurata) was studied at two proportions (100 or 500 µg/kg of feed). Both experimental diets show an increase in growth performance, as well as in feed efficiency after 97 days of experiment. The lower inclusion of GHRP-6 (100 µg/kg) results in a better aerobic metabolism, while the higher inclusion significantly increased plasma GH levels in agreement with the GH secretagogue effects of ghrelin. Similar growth outcome and differences between GHRP-6 levels in aerobic metabolism and GH stimulation suggest that improvements in culture performance by this peptide may occur through different mechanisms. Taken together, this compound can be considered as a viable dietary supplement for increasing production efficiency of sea bream aquaculture, although a better understanding of its dose-specific effects is still required.

The present research tested the effects of dietary nisin-producing Lactococcus lactis on growth performance, feed utilization, intestinal morphology, transcriptional response, and microbiota in gilthead sea bream (Sparus aurata). A feeding trial was conducted with fish weighting 70–90 g. Fish were tagged with passive, integrated transponders and distributed in nine 500 L tanks with 40 fish each. Fish were fed for 12 weeks with either a control (diet A) or experimental diets (diets B and C) in triplicate (3 tanks/diet). Extruded pellets of diets B and C were supplemented with a low (2 × 109 CFU/kg) and a high (5 × 109 CFU/kg) dose of probiotic, respectively. No significant differences were found between groups for the feed conversion ratio or specific growth rates. However, the final body weight of fish fed diet C was significantly higher than the control group with intermediate values for fish fed diet B. Histological analysis conducted using a semi-quantitative scoring system showed that probiotic did not alter the morphology of the intestine and did not trigger inflammation. With regard to the transcriptomic response, a customized PCR array layout was designed to simultaneously profile a panel of 44 selected genes. Significant differences in the expression of key genes involved in innate and acquired immunity were detected between fish fed probiotic and control diets. To analyze the microbiota associated to the feeds and the gut autochthonous microbial communities, we used the Illumina MiSeq platform for sequencing the 16S rRNA gene and a metagenomics pipeline based on VSEARCH and RDP databases. The analysis of gut microbiota revealed a lack of colonization of the probiotic in the host’s intestinal mucosa. However, probiotic did modulate the fish gut microbiota, confirming that colonization is not always necessary to induce host modification. In fact, diets B and C were enriched with Actinomycetales, as compared to diet A, which instead showed a higher percentage

On-growing juveniles of gilthead sea bream were acclimated for 45 days to mild-hypoxia (M-HYP, 40–60% O2 saturation), whereas normoxic fish (85–90% O2 saturation) constituted two different groups, depending on if they were fed to visual satiety (control fish) or pair-fed to M-HYP fish. Following the hypoxia conditioning period, all fish were maintained in normoxia and continued to be fed until visual satiation for 3 weeks. The time course of hypoxia-induced changes was assessed by changes in blood metabolic landmarks and muscle transcriptomics before and after exhaustive exercise in a swim tunnel respirometer. In M-HYP fish, our results highlighted a higher contribution of aerobic metabolism to whole energy supply, shifting towards a higher anaerobic fitness following normoxia restoration. Despite these changes in substrate preference, M-HYP fish shared a persistent improvement in swimming performance with a higher critical speed at exercise exhaustion. The machinery of muscle contraction and protein synthesis and breakdown was also largely altered by mild-hypoxia conditioning, contributing this metabolic re-adjustment to the positive regulation of locomotion and to the catch-up growth response during the normoxia recovery period. Altogether, these results reinforce the presence of large phenotypic plasticity in gilthead sea bream, and highlights mild-hypoxia as a promising prophylactic measure to prepare these fish for predictable stressful events.

Gill monogenean Sparicotyle chrysophrii is considered the most detrimental fish parasite to the Mediterranean aquaculture. Treatment of sparicotylosis relies on frequent gill inspections correlated with the seasonal increase in seawater temperature, application of functional feeds, and treatments with formalin baths where permitted. While the latter is bound to be banned in Europe, other synthetic anthelminthics, such as praziquantel and ivermectin, are prone to induce resistance in the parasites. Therefore, we investigated, in vitro, 14 synthetic and natural compounds against adult S. chrysophrii, developing dose–response modelsm and estimated toxicity levels at 20%, 50%, and 80% parasite mortality. Bactericidal activity of target compounds was also tested in two important aquaculture bacteria; Vibrio harveyi and V. anguillarum, while their potential host toxicity was evaluated in gilthead seabream SAF-1 cell line. Synthetic compound bithionate sodium exerted the most potent toxicity against the monogenean, no host cytotoxicity, and a medium and high potency against two bacterial pathogens. In comparison, target natural compounds were approximately 20 (cedrol) or up to 154 times (camphor) less toxic for the monogenean. Rather than completely dismissing natural compounds, we suggest that their application in combination with synthetic drugs, especially if administered in the feed, might be useful in sparicotylosis treatment.

The biosensor technology has the potential to revolutionize the aquaculture industry, but the selection of tagging method, operational mode (stand-alone vs. wireless systems) and telemetry technology ultimately depends on living species, life stage and research question. In particular, AEFishBIT is a small and stand-alone device composed of a tri-axial accelerometer, a microprocessor, a battery, and a RFID tag that was designed to be externally attached to the operculum. This unique location serves to provide simultaneous measurements of activity patterns (signals of x- and y-axes) and respiratory frequency (z-axis signal) processed by on-board algorithms. The validity of measurements was initially proved in exercised fish in a swim tunnel respirometer, and its use as a reliable tool for the individual monitoring of whole-organism traits in free-swimming gilthead sea bream was tested then in fish facing a wide range of biotic and abiotic stressors. The impact of the tagging method, based on the use of monel piercing fish tags with a flexible heat shrink polyethylene ring, was also evaluated and no signs of growth impairment, operculum damage or gill lamellae haemorrhage were found 10 days post-tagging. The autonomy of the device was 6 hours of continuous recording with re-programmable lag times and recording schedules of 2 min windows at regular intervals along the experimental period (2-8 days). Such procedure underlined a negative linear correlation between fasting weight loss and operculum breaths, becoming respiratory frequency a reliable indicator of basal metabolic rates. Biosensing signals also highlighted the more continuous physical activity and increased respiratory rates of young fish when comparisons were made between one- and three-year old fish. Also, AEFishBIT measurements evidenced a generalized increase of respiratory frequency during severe hypoxia (2-3 ppm), but the individuals classified as proactive fish also shared an increased physical activit

Megalocytiviruses have caused mass mortalities in various farmed fish species, both edible and ornamental. Infectious spleen and kidney necrosis virus (ISKNV) belongs to this family of viruses and induces lethal diseases in cultured fish. Here, we publish the first report describing this epizootic virus affecting the sea bream (Sparus aurata) in the offshore mariculture farm located in the Mediterranean Sea in Israel. The infectious agent was diagnosed with histology analysis and was identified as ISKNV by PCR.

In the context of Mediterranean aquaculture many efforts have been made in terms of reducing marine-derived ingredients in aquafeed formulation. On the other hand, little attention has been paid to the manipulation of feeding frequency at the on-growing phase, where the high costs related to feeding procedures and the optimisation of feed efficiency and fish health are key aspects for the economic and environmental sustainability of the production cycle. The effects of different feeding frequencies (F) (1F) one meal day−1, (2F) two meals day−1, (3F) three meals day−1 on growth, digestive enzyme activity, feed digestibility and plasma biochemistry were studied in gilthead sea bream (Sparus aurata, L. 1758) fed with high (FM30/FO15, 30% fishmeal FM, 15% fish oil, FO) and low (FM10/FO3; 10% FM and 3% FO) FM and FO levels. Isonitrogenous and isolipidic extruded diets were fed to triplicate fish groups (initial weight: 88.3 ± 2.4 g) by a fixed ration over 109 days. No significant effects of feeding frequency on overall performance, feed efficiency and feed digestibility during the on-growing of gilthead sea bream fed high or low fishmeal and fish oil dietary level were observed. Pepsin activity showed an apparent decrease in fish receiving more than one meal a day which was not compensated by an increased production of alkaline proteases (either trypsin or chymotrypsin), particularly in fish fed on low FM. Although there were no effects on growth and feed utilisation at increasing feeding frequency, trypsin decreased significantly with an increasing number of meals only under low FMFO diet. Thus, it seemed that consecutive meals could have amplified the potential trypsin inhibitor effect of the vegetable meal-based diet adopted. Most of the plasma parameters related to nutritional and physiological conditions were not affected by feeding frequency, however an effect on electrolytes (Na+, Cl), cortisol and creatinine was observed. The higher level of plasma creatinine det

The present study evaluated, in an 18-month gilthead sea bream trial, the time course effects of genetics on individual size variation and growth compensation processes in the offspring of families selected by growth in the PROGENSA breeding program. Families categorized as fast, intermediate and slow growing had different growth trajectories with a more continuous growth in fast growth families. This feature was coincident with a reduced size variation at the beginning of the trial that clustered together the half-sib families sharing the same father. Correlation analysis evidenced that the magnitude of compensatory growth was proportional to the initial size variation with no rescaling of families at this stage. By contrast, the finishing growth depensation process can mask, at least partially, the previous family convergence. This reflects the different contribution across the production cycle of genetics and environmental factors in growth, production and welfare. How early life experiences affect growth compensatory at juvenile stages was also evaluated in a separate cohort, and intriguingly, a first mild-hypoxia pulse at 60-81 days posthatching (dph) increased survival rates by 10% preventing growth impairment when fish were exposed to a second hypoxia episode (112-127 dph). The early hypoxia experience did not have a negative impact on growth compensatory processes at juvenile stages. By contrast, a diminished capacity for growth compensation was found with repeated or late hypoxia experiences. All this reinforces the use of size variation as a main criterion for improving intensive fish farming or selective breeding into practice.

Farmed gilthead sea bream (Sparus aurata) is able to grow efficiently with new feed formulations based on plant ingredients. Here, two experimental diets with standard and high inclusion levels of plant ingredients were formulated to assess the suited use of plant-based diets in fish with different growth genetic backgrounds. To pursue this issue, a long-term feeding trial (12-months) was conducted with fish (17 g initial body weight) of 16 families coming from the broodstock of PROGENSA project, that were grown communally in the IATS-CSIC experimental facilities. All fish in the study (2545) were PIT-tagged, and their pedigree was re-constructed with 96% success by using a SMsa1 multiplex of 11 microsatellites, which revealed the main parents contributions of 5 females and 6 males. Each diet was randomly assigned to replicate 3000 L tanks, gathering each replicate a similar family composition through all the feeding trial. Data on growth performance highlighted a strong genetic effect on growth trajectories, associated with enhanced growth during winter in fish selected for faster growth. No main dietary effects were found on growth rates or condition factor, and regression-correlation analyses of growth rates across families on both diets suggest that genome by diet interaction was weak, while genetic variation accounted for most of the growth phenotypic variation. Hepatosomatic index (HSI) and mesenteric fat index (MSI) of five families, covering the growth variability of the population, were regulated nutritionally and genetically, but without statistically significant genome by diet interactions. Fish from faster growing families showed shorter intestines after being fed the control diet, but this phenotype was masked by the enriched plant-based diet. Collectively, the results demonstrate that selection for faster growth is associated in gilthead sea bream with different growth trajectories and a high diet flexibility and intestine plasticity.

Passive immunization is used in humans for treating or preventing some infectious diseases, but it also constitutes an emerging field of interest in aquaculture, particularly with the restrictions for antibiotic use. Intracoelomically-injected antibodies can be detected in fish sera within the first 8 h and their half-life ranges from 7 to 22 days post-injection, depending on the species. The fish models studied so far used fast-acting pathogens such as virus, bacteria or ciliate parasites. The current work aimed to determine if passive immunization could help to prevent enteromyxosis in gilthead sea bream (GSB, Sparus aurata). Enteromyxum leei is a myxozoan intestinal parasite that invades the paracellular space of the intestinal epithelium, producing a slow-progressing disease, leading to anorexia, cachexia and mortalities. We have previously demonstrated that GSB that survive E. leei infection become resistant upon re-exposure, and this resistance is directly related to the presence of high levels of specific serum antibodies. In the current study, we evaluated whether injection with sera from resistant animals would protect naïve fish when challenged by effluent exposure to the parasite. Serum from a pool of resistant (R) and naïve (N) animals (intact or heat inactivated, 10 ¿l/g BW) was intracoelomically injected 24 h prior to the E. leei-effluent challenge and at 9 days post-challenge (dpc). At 23 dpc, the different groups were allocated in separate tanks and the effluent exposure was terminated. A non-lethal parasite diagnosis was performed at 56 dpc. At the final sampling (100 dpc), blood, serum and tissues were collected for hematology, circulating antibodies, histological and molecular diagnosis and gene expression. Groups injected with R sera had lower prevalence and intensity of infection than those with N sera, both in the intermediate and final samplings. At 100 dpc, the prevalence of infection in the PBS and N groups was 70%, whereas in R group it onl

Intestinal microbiota is key for many host functions, such as digestion, nutrient metabolism and absorption, disease resistance and immune function. With the growth of the aquaculture industry, there has been a growing interest in the manipulation of fish gut microbiota to improve welfare and nutrition (Egerton et al., 2018). However, a long road lies ahead to establish the baseline parameters to guide this manipulation. Intestinal microbiota varies with many factors, including host species, genetics, developmental stage, diet, environment and sex. The aim of this study was to compare the intestinal microbiota of adult gilthead sea bream (GSB, Sparus aurata) from three groups of age maintained under the same conditions. One-, 2- and 4-year old GSB (Y+1, Y+2, Y+4) were kept in the same open-flow system and fed the same diet for more than 6 months. After 2-days of fasting, 10 fish per group were sacrificed and the anterior intestinal portion was dissected, opened and washed to remove non-adherent bacteria. Intestinal mucus was scrapped off and immediately used for DNA extraction. The V3-V4 region of the 16S rRNA of each individual sample was amplified and sequenced by Illumina MiSeq. All Y+1 individuals were males, while the ones belonging to Y+2 and Y+4 age classes were females. A total of 686461 high quality reads (22882/sample) were assigned to 846 OTUs (97% identity). Almost 30% of the OTUs were classifiedup to the level of species. Microbiota diversity and richness did not differ among age groups; however bacterial composition did , highlighting the presence of Photobacterium and Vibrio only after 2 years of age and a higher presence of Staphylococcusand Corynebacterium in Y+1 animals. The core microbiota was defined by 14 OTUs and the groups that showed more OTUs in common were Y+2 and Y+4. PLS-DA analysis showed a clear separation by sex (component 1) and age (component 2), with bacteria belonging to the phyla Firmicutes, Proteobacteria and Actinobacteria drivi

[Background]:In the animal production sector, enteritis is responsible for serious economic losses, and intestinal parasitism is a major stress factor leading to malnutrition and lowered performance and animal production efficiency. The effect of enteric parasites on the gut function of teleost fish, which represent the most ancient bony vertebrates, is far from being understood. The intestinal myxozoan parasite Enteromyxum leei dwells between gut epithelial cells and causes severe enteritis in gilthead sea bream (Sparus aurata), anorexia, cachexia, growth impairment, reduced marketability and increased mortality., [Methods]: This study aimed to outline the gut failure in this fish-parasite model using a multifaceted approach and to find and validate non-lethal serum markers of gut barrier dysfunction. Intestinal integrity was studied in parasitized and non-parasitized fish by immunohistochemistry with specific markers for cellular adhesion (E-cadherin) and tight junctions (Tjp1 and Cldn3) and by functional studies of permeability (oral administration of FITC-dextran) and electrophysiology (Ussing chambers). Serum samples from parasitized and non-parasitized fish were analyzed using non-targeted metabolomics and some significantly altered metabolites were selected to be validated using commercial kits., [Results]: The immunodetection of Tjp1 and Cldn3 was significantly lower in the intestine of parasitized fish, while no strong differences were found in E-cadherin. Parasitized fish showed a significant increase in paracellular uptake measured by FITC-dextran detection in serum. Electrophysiology showed a decrease in transepithelial resistance in infected animals, which showed a diarrheic profile. Serum metabolomics revealed 3702 ions, from which the differential expression of 20 identified compounds significantly separated control from infected groups in multivariate analyses. Of these compounds, serum inosine (decreased) and creatine (increased) were identified as relevant and validated with commercial kits., [Conclusions]: The results demonstrate the disruption of tight junctions and the loss of gut barrier function, a metabolomic profile of absorption dysfunction and anorexia, which further outline the pathophysiological effects of E. leei.

Farmed gilthead sea bream (Sparus aurata) is able to grow efficiently with new feed formulations based on plant ingredients. Here, two experimental diets with standard and high inclusion levels of plant ingredients were formulated to assess the suited use of plant-based diets in fish with different growth genetic backgrounds. To pursue this issue, a long-term feeding trial (12-months) was conducted with fish (17 g initial body weight) of 16 families coming from the broodstock of PROGENSA project, that were grown communally in the IATS-CSIC experimental facilities. All fish in the study (2545) were PIT-tagged, and their pedigree was re-constructed with 96% success by using a SMsa1 multiplex of 11 microsatellites, which revealed the main parents contributions of 5 females and 6 males. Each diet was randomly assigned to replicate 3000 L tanks, gathering each replicate a similar family composition through all the feeding trial. Data on growth performance highlighted a strong genetic effect on growth trajectories, associated with enhanced growth during winter in fish selected for faster growth. No main dietary effects were found on growth rates or condition factor, and regression-correlation analyses of growth rates across families on both diets suggest that genome by diet interaction was weak, while genetic variation accounted for most of the growth phenotypic variation. Hepatosomatic index (HSI) and mesenteric fat index (MSI) of five families, covering the growth variability of the population, were regulated nutritionally and genetically, but without statistically significant genome by diet interactions. Fish from faster growing families showed shorter intestines after being fed the control diet, but this phenotype was masked by the enriched plant-based diet. Collectively, the results demonstrate that selection for faster growth is associated in gilthead sea bream with different growth trajectories and a high diet flexibility and intestine plasticity.

The development of Genotyping-By-Sequencing (GBS) technologies enables cost-effective analysis of large numbers of Single Nucleotide Polymorphisms (SNPs), especially in “non-model” species. Nevertheless, as such technologies enter a mature phase, biases and errors inherent to GBS are becoming evident. Here, we evaluated the performance of double digest Restriction enzyme Associated DNA (ddRAD) sequencing in SNP genotyping studies including high number of samples. Datasets of sequence data were generated from three marine teleost species (>5500 samples, >2.5 × 1012 bases in total), using a standardized protocol. A common bioinformatics pipeline based on STACKS was established, with and without the use of a reference genome. We performed analyses throughout the production and analysis of ddRAD data in order to explore (i) the loss of information due to heterogeneous raw read number across samples; (ii) the discrepancy between expected and observed tag length and coverage; (iii) the performances of reference based vs. de novo approaches; (iv) the sources of potential genotyping errors of the library preparation/bioinformatics protocol, by comparing technical replicates. Our results showed use of a reference genome and a posteriori genotype correction improved genotyping precision. Individual read coverage was a key variable for reproducibility; variance in sequencing depth between loci in the same individual was also identified as an important factor and found to correlate to tag length. A comparison of downstream analysis carried out with ddRAD vs single SNP allele specific assay genotypes provided information about the levels of genotyping imprecision that can have a significant impact on allele frequency estimations and population assignment. The results and insights presented here will help to select and improve approaches to the analysis of large datasets based on RAD-like methodologies

European fish farming drives the development of sustainable marine fish feed where marine ingredients are replaced by alternatives such as plant meals and vegetable oils. A new scenario emerges where noncurrent and/or new contaminants enter into the fish food chain as potential food safety and/or welfare concerns. Novel analytical methodologies must be developed to assess the large variety of contaminants from different families in feed ingredients, feeds based on these ingredients and fish farmed on the novel feeds. Of the novel contaminants identified in feed ingredients and feeds, the pesticides, such as chlorpyrifos‐methyl, pirimiphos‐methyl, boscalid and azoxystrobin, and the mycotoxins, such as deoxynivalenol and fumonisins (B1 + B2 + B3), were detected. Polyaromatic hydrocarbons, especially those with ≤4 ring, were found in all samples. Information of the transfer of contaminants from feed to public foodstuffs is essential for an appropriate human risk assessment of feed contaminants as well as for the harmonization of legislation of contaminants throughout the aquaculture production chain. However, the pesticides and mycotoxins found in feed were not detected in fish fillet, and hence, no transfer factor could be established. As a result, no apparent risk seems to be associated with these contaminants in fish fillets at the current background exposure levels by feeds

The development of Genotyping-By-Sequencing (GBS) technologies enables cost-effective analysis of large numbers of Single Nucleotide Polymorphisms (SNPs), especially in "non-model" species. Nevertheless, as such technologies enter a mature phase, biases and errors inherent to GBS are becoming evident. Here, we evaluated the performance of double digest Restriction enzyme Associated DNA (ddRAD) sequencing in SNP genotyping studies including high number of samples. Datasets of sequence data were generated from three marine teleost species (>5500 samples, >2.5 × 1012 bases in total), using a standardized protocol. A common bioinformatics pipeline based on STACKS was established, with and without the use of a reference genome. We performed analyses throughout the production and analysis of ddRAD data in order to explore (i) the loss of information due to heterogeneous raw read number across samples; (ii) the discrepancy between expected and observed tag length and coverage; (iii) the performances of reference based vs. de novo approaches; (iv) the sources of potential genotyping errors of the library preparation/bioinformatics protocol, by comparing technical replicates. Our results showed use of a reference genome and a posteriori genotype correction improved genotyping precision. Individual read coverage was a key variable for reproducibility; variance in sequencing depth between loci in the same individual was also identified as an important factor and found to correlate to tag length. A comparison of downstream analysis carried out with ddRAD vs single SNP allele specific assay genotypes provided information about the levels of genotyping imprecision that can have a significant impact on allele frequency estimations and population assignment. The results and insights presented here will help to select and improve approaches to the analysis of large datasets based on RAD-like methodologies.

[EN] The search for new sustainable aquafeeds for the species with greater economic importance, such as the gilthead sea bream in Europe, is one of the main challenges in the aquaculture sector. The present work tested fishmeal replacement by a mixture of plant meals at different levels, as well as the use of marine by-products with attractant properties and high-quality protein in high plant protein diets. In order to do that, effects on growth and biometric parameters, digestibility, amino acid retention, excreted ammonia and proteases and amylase activity were assessed, using six different diets: FM100 (100% of protein provided by fishmeal), FM50 (50% of replacement), FM25 (75% of replacement) and FM0 (100% of replacement), but also FM25+ (75% of replacement and 15% of squid and krill meal inclusion), and FM0+ (100% of replacement and 15% of squid and krill meal inclusion). In group FM0, a clear impact of dietary changes was observed on growth, survival and ammonia excretion. Amino acid retention in group FM0+ was also significantly affected, which can be explained by the limited content of certain amino acids in this diet. On the other hand, no significant differences were observed in most biometric parameters or in enzyme activity. In conclusion, complete fishmeal replacement can be achieved by using a mixture of plant-based sources, but supplementation with complementary marine ingredients can prevent detrimental effects on growth, survival, nutritional parameters and protein metabolism.

[Backgroud] Enteromyxum leei is a myxozoan parasite that produces a slow-progressing intestinal disease. This parasite invades the paracellular space of the intestinal epithelium and progresses from the posterior to the anterior intestine. The aim of the present study was to gain insights into fish T cell responses in the gilthead sea bream-E. leei infection model using a PCR-array with 30 signature molecules for different leukocyte responses in head kidney, spleen, anterior and posterior intestine., [Results] The PCR-array results suggest that E. leei induced migration of T cells from head kidney to intestines where TH1, CTL and TH17 profiles were activated and kept in balance by the upregulation of regulatory cytokines. These results were partially validated by the use of cross-reacting antibodies and BrdU immunostaining to monitor proliferation. Zap70 immunostaining supported the increased number of T cells in the anterior intestine detected by gene expression, but double staining with BrdU did not show active proliferation of this cell type at a local level, supporting the migration from lymphohaematopoietic tissues to the site of infection. Global analyses of the expression profiles revealed a clear separation between infected and exposed, but non-infected fish, more evident in the target organ. Exposed, non-infected animals showed an intermediate phenotype closer to the control fish., [Conclusions] These results evidence a clear modulation of the T cell response of gilthead sea bream upon E. leei infection. The effects occurred both at local and systemic levels, but the response was stronger and more specific at the site of infection, the intestine. Altogether, this research poses a promising basis to understand the response against this important parasite and establish effective preventive or palliative measures.

[ES] La acuicultura está en continuo crecimiento, sin embargo, las harinas y los aceites de pescado son un recurso que está en decadencia, es por ello que la industria se ha visto forzada a investigar materias primas alternativas para alimentar a los peces. En la actualidad se está invirtiendo tiempo y esfuerzo en la investigación de fuentes de aceites y harinas vegetales y animales, así como en los niveles óptimos que se deben incluir en la dieta de las diferentes especies de peces. El objetivo de este trabajo es valorar el efecto de la sustitución de la harina de pescado por una mezcla de harinas animales y vegetales (harina de carne de cerdo ibérico, harina de soja, de guisante y de girasol), en el crecimiento y parámetros nutritivos de la dorada (Sparus aurata). Para ello, se ensayarán 5 piensos experimentales en los que la harina de pescado se sustituirá en un 75, 90 y 100%. Habrá dos dietas con el 100% de sustitución (FM 0 y FM 0+), con la diferencia que FM 0+ contendrá un 5% de alga. Se trabajará con juveniles de dorada (50g de peso inicial). Al inicio y en cada muestreo, se pesarán todos los peces para luego estimar el peso final (Pf) y la tasa de crecimiento instantáneo (TCI). Asimismo se calculará la tasa de alimentación diaria (TAD) y el índice de conversión del alimento (ICA). Diariamente, se realizarán una serie de controles para comprobar el correcto funcionamiento del laboratorio: revisión general de la instalación, control de calidad del agua, control de crecimiento, etc.; así como la alimentación de los peces dos veces al día. Los controles de peso se realizarán cada 4 semanas y los peces serán alimentados hasta saciedad aparente. Al inicio y final de cada experimento se sacrificarán los peces con un exceso de esencia de clavo y se realizarán los análisis químicos: macronutrientes (siguiendo la metodología descrita por la AOAC, 1990) y los aminoácidos totales (mediante cromatografía líquida de alta resolución, HPLC) de los piensos fabricados y de lo, [EN] Aquaculture is in continuous growth, however, fishmeal and fish oils are a resource that is in decline, which is why the industry has been forced to investigate alternative raw materials to feed the fish. At present, time and effort are being invested in the research of sources of vegetable and animal oils and flours as well as the optimum levels to be included in the diet of different fish species. The objective of this work is to evaluate the effect of substitution of fish meal for a mixture of animal and vegetable flours (Iberic pig meal, soybean meal, pea and sunflower meal), growth and nutritional parameters of the gilthead sea bream (Sparus aurata). To do this, 5 experimental feeding stuffs will be tested in which the fish meal will be replaced in 75, 90 and 100%. There will be two diets with 100% substitution (FM 0 and FM 0+); with the difference that FM 0+ will contain 5% algae. It will work with juveniles of gilthead sea bream (50g of initial weight). At the beginning and in each sampling, all the fish will be weighed and then the final weight (Fw) and the specific growth rate (SGR) will be estimated. The feed intake ratio (FI) and the feed conversion ratio (FCR) will also be calculated. Daily, a series of controls will be carried out for the correct functioning of the laboratory: general revision of the installation, water quality control, growth control, etc., as well as feeding of the fish twice a day. Weight checks will be performed every 4 weeks and the fish will be fed to apparent satiety. At the beginning and at the end of each experiment the fish will be sacrificed with an excess of clove oil and the chemical analyzes will be performed: macronutrients (following the methodology described by AOAC, 1990) and total amino acids (by high performance liquid chromatography, HPLC) of the manufactured feed and the fish. From each sample, all the analyses were performed in triplicate.

The gilthead sea bream (Sparus aurata L.) is one of the most important marine fish species produced in southern European countries. Over the last two decades, microsatellites have become a powerful tool for DNA studies of fish populations, making it possible to establish existing genealogical relationships between individuals and to perform reliable estimates of genetic parameters. In the present study, a total of 7959 fish (494 breeders and 7465 fry) were genotyped using two rounds of multiplex reactions with four microsatellite markers each. Offspring were assigned based on the Mendelian exclusion principles, using FAP program. Genealogical information was successfully obtained for more than 83 % of the progeny. Heritability estimates were close to 0.40 in all cases and for all considered traits. The lowest value was for the length at first age (350 ± 6 dph) and the highest for the length at the second age (500 ± 7 dph). The heritabilities for the first and the second weight were similar although somewhat higher for the second age, but not significant. The highest genetic correlations were found between weight and length at the same age and the lowest between weight and length at different ages. Based on the results of this study, it seems reasonable to expect that the implementation of a breeding program for improved growth in this population of gilthead sea bream will offer comparable performances to those achieved in other populations and species of great success in aquaculture around the world. © 2016, Springer International Publishing Switzerland.

The seven sirtuin (SIRT) counterparts of higher vertebrates were identified and molecularly characterized in a farmed fish of the Sparidae family, order Perciformes. These proteins are NAD+-dependent deacetylases that couple protein deacetylation with the energy status of the cell via the cellular NAD+/NADH ratio with a strict conservation of the characteristic catalytic domain surrounded by divergent N- and C- terminal regions. Phylogenetic analysis showed three major clades corresponding to SIRT1–3, SIRT4–5, and SIRT6–7 that reflected the present hierarchy of vertebrates and the accepted classification of SIRTs. Transcriptional studies revealed a ubiquitous SIRT gene expression that was tissue-specific for each SIRT. This was evidenced by multivariate analyses, which established two main clusters corresponding to SIRTs with relatively high (SIRT1, 2, and 5) and low (SIRT3, 4, 6, and 7) gene expression levels. A nutritional regulation was also evidenced in 10-day fasted fish, and SIRT2–4 exhibited an overall downregulated expression. SIRT1, 5, 6, and 7 were mostly upregulated, although clustering analyses evidenced a highly regulated response that was different for each SIRT according to the different tissue metabolic capabilities. These findings supported the use of SIRTs alone or in combination with other biomarkers for the metabolic phenotyping of farmed fish and gilthead sea bream in particular.

The seven sirtuin (SIRT) counterparts of higher vertebrates were identified and molecularly characterized in a farmed fish of the Sparidae family, order Perciformes. These proteins are NAD+-dependent deacetylases that couple protein deacetylation with the energy status of the cell via the cellular NAD+/NADH ratio with a strict conservation of the characteristic catalytic domain surrounded by divergent N- and C- terminal regions. Phylogenetic analysis showed three major clades corresponding to SIRT1–3, SIRT4–5, and SIRT6–7 that reflected the present hierarchy of vertebrates and the accepted classification of SIRTs. Transcriptional studies revealed a ubiquitous SIRT gene expression that was tissue-specific for each SIRT. This was evidenced by multivariate analyses, which established two main clusters corresponding to SIRTs with relatively high (SIRT1, 2, and 5) and low (SIRT3, 4, 6, and 7) gene expression levels. A nutritional regulation was also evidenced in 10-day fasted fish, and SIRT2–4 exhibited an overall downregulated expression. SIRT1, 5, 6, and 7 were mostly upregulated, although clustering analyses evidenced a highly regulated response that was different for each SIRT according to the different tissue metabolic capabilities. These findings supported the use of SIRTs alone or in combination with other biomarkers for the metabolic phenotyping of farmed fish and gilthead sea bream in particular

A metabolomic study has been performed to identify sensitive and robust biomarkers of malnutrition in farmed fish, using gilthead sea bream (Sparus aurata) as a model. The metabolomic fingerprinting of serum from fasted fish was assessed by means of ultra-high performance liquid chromatography coupled to quadrupole time-offlight mass spectrometry. More than 15,000 different m/z ions were detected and Partial Least Squares–Discriminant analysis allowed a clear differentiation between the two experimental groups (fed and 10-day fasted fish) with more than 90% of total variance explained by the two first components. The most significant metabolites (up to 45) were elucidated on the basis of their tandem mass spectra with a broad representation of amino acids, oligopeptides, urea cycle metabolites, L-carnitinerelated metabolites, glutathione-related metabolites, fatty acids, lysophosphatidic acids, phosphatidylcholines as well as biotin- and noradrenaline-related metabolites. This untargeted approach highlighted important adaptive responses in energy and oxidative metabolism, contributing to identify robust and nutritionally-regulated biomarkers of health and metabolic condition that will serve to assess the welfare status of farmed fish.

[EN] Target strength (TS) measurements for ventral aspect of gilthead sea bream (Sparus aurata) have been performed in a scaled aquaculture cage. The measurements have been made with a Simrad EK-60 scientific echososunder working at 200 kHz with a single-beam composted transducer specific of the Simrad ES15 echosounder (aperture of 30 degrees), designed for aquaculture control among other applications. Linear relationships of TS versus the logarithms of length have been derived. It must been underlined the obtaining of high values of the correlation coefficients and a high resolution of the ventral expressions for fish size predictions. Lower mean values of TS distributions are obtained for single-beam mesurements respect split-beam measurements as expected.

In the present study, the nutritional value of Tetraselmis suecica and Tisochrysis lutea (previously known as Isochrysis aff galbana T-ISO strain) freeze-dried biomass for feeding Sparus aurata fry was evaluated. A total of 25,500 fry (3.7 mg body weight) were fed for 55 days on diets containing 5 and 10%(w/w) Tetraselmis or Tisochrysis, as well as on a microalgae-free diet. Fish fed 5 % Tetraselmis showed higher growth performance, nutrient utilization, and survival values than fish fed Tisochrysis. The use of microalgae significantly decreased the body lipid content in fry fed the highest microalgae level. Fry fed Tisochrysis-supplemented diets increased the DHA content in muscle, and consequently the EPA/DHA ratio decreased significantly, whatever dietary level considered. In general, digestive protease activities were not adversely affected by dietary microalgae inclusion, although slight variations were observed during fish development. Microalgae utilization causes a positive effect on intestinal mucosa ultrastructure owing to an increase of total enterocyte absorption surface that was observed in fish fed microalgae-supplemented diets. Cluster analysis of data separated clearly fish fed Tisochrysis-supplemented diets from the rest of experimental groups. This study confirms that Tetraselmis freeze-dried biomass can be used as dietary ingredient in started feeds for S. aurata fry, although an inclusion level of 5 % is recommended.

[ESP] El objetivo de esta Tesis fue obtener información relevante para el desarrollo de un programa de mejora genética en dorada. Con este fin, se obtuvo una población de alevines de dorada, a partir de tres lotes de reproductores diferentes [Mar Cantábrico (CAN); n = 59, 2?:1?; Océano Atlántico (ATL); n = 98, 1?:1? y Mar Mediterráneo (MED); n = 47; 1?:1?]. Los alevines fueron marcados para su identificación individual con Passive Integrated Transponder y criados bajo las mismas condiciones industriales hasta su sacrificio. Esta población fue analizada para desarrollar diversos objetivos concretos que se centraron en estudiar algunos aspectos escasamente tratados o desconocidos en dorada. Inicialmente se estudió la variabilidad y la estructuración genética de esta población, caracterizando genéticamente, mediante marcadores microsatélites, tanto reproductores como descendientes. Además se establecieron sus relaciones de parentesco y se estudiaron las contribuciones a la puesta. Los resultados mostraron que los tres orígenes estudiados presentaron una alta variabilidad genética y fueron diferentes genéticamente entre sí. Además, las contribuciones de los reproductores de los diferentes orígenes fueron desiguales por lo que su tamaño efectivo disminuyó. Se formaron un total de 201 familias de hermanos completos, más 21 familias de medios hermanos paternos y 9 familias de medios hermanos maternos. Seguidamente se analizó el efecto del origen de los reproductores sobre caracteres de interés comercial, lo que proporcionaría información fenotípica relevante para la adquisición de un stock. Así mismo, se estimaron parámetros genéticos (heredabilidades y correlaciones genéticas) y correlaciones fenotípicas para dichos caracteres con el fin de determinar posibles criterios de selección. Los caracteres crecimiento y presencia de malformaciones esqueléticas externas fueron analizados a diferentes edades iniciales (163, 368 y 516 días) así como a la edad de sacrificio (690 días

In this paper we analyze consumers’ preferences for gilthead sea bream in Catalonia by means of a Choice Experiment (CE). Data used are obtained from a structured questionnaire applied to 160 gilthead sea bream consumers. Results show that consumers’ preferences for this species are highly heterogeneous. However, a main trend has been shown which describes that the most appreciated product attributes are presentation and price., Postprint (published version)

The development of restructured fish products and the application of new food ingredients have been used to create attractive new products and also to upgrade low-value species. The aim of this study was to evaluate the effect of konjac gum (KGM) and carboxymethylcellulose (CMC) fibres on the mechanical and physico-chemical properties of microbial transglutaminase treated restructured fish products from gilthead sea bream as well as to evaluate the effect of heat treatment and storage time. Water holding capacity, mechanical properties and colour attributes in fresh and heat-treated samples after 15 days of cold storage were measured. Results showed that these edible gums could be appropriate for making restructured products obtained from gilthead sea bream. In fresh formulations the addition of 10 gkg−1 of KGM or 10 gkg−1 of CMC presented a significant effect (p¡Ü0.05) on water activity for fresh samples and the lowest value was obtained for 10 gkg−1 of KGM (0.975¡À0.002). Water holding capacity and adhesiveness increased due to the presence of these gums in fresh and heat-treated samples. For heattreated samples, KGM significantly reduced (p<0.05) hardness, cohesiveness and chewiness. Cryo-scanning electron microscopy revealed different structures for gels containing fibres. The use of these fibres did not induce significant changes in colour parameters. Fresh or heattreated samples stored for 15 days at 4¡ãC showed changes in relation to the parameters investigated.

In this study, we have evaluated the incorporation of two types of protein hydrolysates at 9 and 12% levels of inclusion, one from yeast (Saccharomyces cerevisiae, YPH) and another one from pig blood (PBPH), in microdiets for gilthead sea bream (Sparus aurora) larvae, and compared these results to a microdiet containing fish protein hydrolysate and another group only fed with enriched live prey (rotifers and Artemia). The trial consisted in substituting up to 75% (wt/wt) the enriched Artemia with the experimental microdiets from 15 to 40 days post-hatch, whereas larvae were exclusively fed on microdiets from 40 to 55 dph. Protein hydrolysates used in the present study were obtained from different raw materials (yeast, pig blood and fish protein concentrate) and differed in their amino acid (AA) profile and in their molecular weight distribution. YPH and PBPH were mainly composed by free amino acids (FAA) (44%, MW<200 Da), di- and tripeptides (50%, 200

Four experimental diets in which fish meal was partially replaced (0, 18, 36 and 55%) by carob seed germ meal (CSGM) were fed to gilthead sea bream (Sparus aurata L.). The results of this experiment demonstrated that CSGM can supply up to 36% of fish meal in diets for feeding g. sea bream without any adverse effect on fish growth, liver and gut.

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. © 2011 Taylor &Francis.

Skeletal muscle development in vertebrates – also termed myogenesis – is a highly integrated process. Evidence to date indicates that the processes are very similar across mammals, poultry and fish, although the timings of the various steps differ considerably. Myogenesis is regulated by the myogenic regulatory factors and consists of two to three distinct phases when different fibre populations appear. The critical times when myogenesis is prone to hormonal or environmental influences depend largely on the developmental stage. One of the main mechanisms for both genetic and environmental effects on muscle fibre development is via the direct action of the growth hormone–insulin-like growth factor (GH–IGF) axis. In mammals and poultry, postnatal growth and function of muscles relate mainly to the hypertrophy of the fibres formed during myogenesis and to their fibre-type composition in terms of metabolic and contractile properties, whereas in fish hyperplasia still plays a major role. Candidate genes that are important in skeletal muscle development, for instance, encode for IGFs and IGF-binding proteins, myosin heavy chain isoforms, troponin T, myosin light chain and others have been identified. In mammals, nutritional supply in utero affects myogenesis and the GH–IGF axis may have an indirect action through the partitioning of nutrients towards the gravid uterus. Impaired myogenesis resulting in low skeletal myofibre numbers is considered one of the main reasons for negative long-term consequences of intrauterine growth retardation. Severe undernutrition in utero due to natural variation in litter or twin-bearing species or insufficient maternal nutrient supply may impair myogenesis and adversely affect carcass quality later in terms of reduced lean and increased fat deposition in the progeny. On the other hand, increases in maternal feed intake above standard requirement seem to have no beneficial effects on the growth of the progeny with myogenesis not or only sli

The present research looked at the ability of gilthead seabream to discriminate between two similar diets differing only in the extent of lipid oxidation. Six groups of 4 fish (254 g initial wet weight) were allowed to be selected by means of self-feeders between two complete diets (34.5% casein + gelatin, 14.8% fish oil + soybean oil, 24.8% dextrin and 25.9% vitamins, minerals, filler and binder) which differed only in the oxidation level of the lipid source: 6.2 meq/kg for the control (D1) and 100.0 meq/kg for the oxidized diet (D2). During the first nine days of the trial, fish took similar amounts of D1 and D2, although there was a clear tendency to gradually avoid D2. Finally, on day 10 fish demanded a significantly higher percentage (82%) of D1. When the diets were interchanged to investigate feeder preferences, two selection patterns were observed: three groups resumed their selection for D1 from day 7 onwards, while the other three groups did not show a clear preference for any diet until they were subjected to a 3-week fasting period (which boosts internal oxidation), after which they significantly selected D1. Taking together the results before and after fasting, gilthead seabream were able to discriminate and avoid a diet with oxidized lipids, and the physiological state of fish (oxidative stress caused by fasting) appeared to reinforce their selection/avoidance behavior.

Several nutritional studies have found a direct effect of several vitamins in chondrogenic and osteogenic development during early life stages of marine fish species. In the present study, the effect of vitamin A (VA) in gilthead sea bream skeletogenesis was evaluated by means of four different dietary regimes (enriched rotifers) containing increasing levels of total VA (75,109, 188 and 723 ng total VA mg(-1) DW). Dietary treatments were offered to larvae during the rotifer-feeding phase (4-20 days after hatching), while later all groups were fed with Artemia nauplii and weaned onto the same inert diet. Different dietary doses of VA affected gilthead sea bream larval growth, survival, performance (maturation of the digestive system) and quality (incidence of skeletal deformities). Higher levels of dietary VA than those included in the commercial emulsion for rotifer enrichment led to different levels and typologies of skeletal deformities, indicating that gilthead sea bream larvae were very sensitive to small increases in dietary VA. The degree of ossification was affected by the level of VA in enriched rotifers: the higher amount of VA in the diet, the higher number of skeletal pieces ossified (R = 0.585, P = 0.04). Dietary VA affected the normal process of bone formation and skeletogenesis, the skeletal structures mostly affected by high amounts of dietary VA were those from the cranial skeleton (splanchnocranium), vertebral centrums and caudal fin complex. The premaxilla, maxilla and dentary bones were the cranial structures affected by dietary VA levels, resulting in a large incidence of animals with compressed snout. Dietary VA also affected the normal development of the opercular complex, and a dose-response dependant effect was observed in relation to the incidence of specimens with incomplete operculum. Body shape was also affected by the level of dietary VA, increasing the incidence of specimens with lordosis, kyphosis and/or scoliosis with the dose of VA

Several nutritional studies have found a direct effect of several vitamins in chondrogenic and osteogenic development during early life stages of marine fish species. In the present study, the effect of vitamin A (VA) in gilthead sea bream skeletogenesis was evaluated by means of four different dietary regimes (enriched rotifers) containing increasing levels of total VA (75, 109, 188 and 723 ng total VA mg− 1 DW). Dietary treatments were offered to larvae during the rotifer-feeding phase (4–20 days after hatching), while later all groups were fed with Artemia nauplii and weaned onto the same inert diet. Different dietary doses of VA affected gilthead sea bream larval growth, survival, performance (maturation of the digestive system) and quality (incidence of skeletal deformities). Higher levels of dietary VA than those included in the commercial emulsion for rotifer enrichment led to different levels and typologies of skeletal deformities, indicating that gilthead sea bream larvae were very sensitive to small increases in dietary VA. The degree of ossification was affected by the level of VA in enriched rotifers: the higher amount of VA in the diet, the higher number of skeletal pieces ossified (R = 0.585, P = 0.04). Dietary VA affected the normal process of bone formation and skeletogenesis, the skeletal structures mostly affected by high amounts of dietary VA were those from the cranial skeleton (splanchnocranium), vertebral centrums and caudal fin complex. The premaxilla, maxilla and dentary bones were the cranial structures affected by dietary VA levels, resulting in a large incidence of animals with compressed snout. Dietary VA also affected the normal development of the opercular complex, and a dose–response dependant effect was observed in relation to the incidence of specimens with incomplete operculum. Body shape was also affected by the level of dietary VA, increasing the incidence of specimens with lordosis, kyphosis and/or scoliosis with the dose of VA

Differential localization and regulation of two aquaporin-1 homologs in the intestinal epithelia of the marine teleost Sparus aurata. Am J Physiol Regul Integr Comp Physiol 294: R993–R1003, 2008. First published January 2, 2008; doi:10.1152/ajpregu.00695.2007.—Aquaporin (AQP)-mediated intestinal water absorption may play a major osmoregulatory role in euryhaline teleosts, although the molecular identity and anatomical distribution of AQPs in the fish gastrointestinal tract is poorly known. Here, we have investigated the functional properties and cellular localization in the intestine of two gilthead seabream (Sparus aurata) homologs of mammalian aquaporin-1 (AQP1), named SaAqp1a and SaAqp1b. Heterologous expression in Xenopus laevis oocytes showed that SaAqp1a and SaAqp1b were water-selective channels. Real-time quantitative RT-PCR and Western blot using specific antisera indicated that abundance of SaAqp1a mRNA and protein was higher in duodenum and hindgut than in the rectum, whereas abundance of SaAqp1b was higher in rectum. In duodenum and hindgut, SaAqp1a localized at the apical brush border and lateral membrane of columnar enterocytes, whereas SaAqp1b was detected occasionally and at very low levels at the apical membrane. In the rectum, however, SaAqp1a was mainly accumulated in the cytoplasm of a subpopulation of enterocytes spread in groups over the surface of the epithelia, including the intervillus pockets, whereas SaAqp1b was detected exclusively at the apical brush border of all rectal enterocytes. Freshwater acclimation reduced the synthesis of SaAqp1a protein in all intestinal segments, but it only reduced SaAqp1b abundance in the rectum. These results show for the first time in teleosts a differential distribution and regulation of two functional AQP1 homologs in the intestinal epithelium, which suggest that they may play specialized functions during water movement across the intestine