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The synergies between selective breeding and feed additives remain under-explored in farmed fish, despite their sustainability. Reference (REF) and selected gilthead sea bream for growth (GS) were fed with the control (CTRL) diet during 14 days. CTRL diet was oil-coated with three functional additives (PHY: phytogenic based on garlic and medium chain fatty acid; OA: organic acid mixture with a 70% of butyric acid sodium salt; PROB: probiotic based on Bacillus subtilis, pumillus and licheniformes species). These experimental diets were then sequentially administered at high (PHY/OA = 7.5 g/kg, PROB = 2 × 1011 CFU/kg; 2 weeks) and low (PHY = 5 g/kg, OA = 3 g/kg, PROB = 4 × 1010 CFU/kg; 10 weeks) additive doses. The capacity of a given genotype and additive to modify the fish growth performance, gut health and the host interaction with its anterior intestine (AI) microbiota was evaluated as a whole population or individually (9 fish/diet/genetics). GS fish showed a better growth and feed conversion ratio, linked to a reduced individual variability of gut microbial composition. The PHY additive had a major impact upon the intestinal transcriptome of GS-PHY fish, with the up-regulation of markers of epithelial integrity, sphingolipid and cholesterol/bile salt metabolism. With the OA additive, impaired growth performance, reduced AI goblet cell area and enhanced AI granulocyte infiltration were concomitant with a down-regulation of neutrophil degranulation markers associated with a decrease of pathogenic genera (Staphylococcus/Streptococcus/Neisseria), and an over-representation of acetone/butanol/ethanol fermentation and vitamin K biosynthesis inferred pathways. Bacillus establishment and lack of AI inflammation were parallel in PROB fish of both genetic backgrounds. However, GS fish grew and utilized feed better with the additive, whereas a worsening appeared in REF fish. This amelioration was related with a higher abundance of the nitrate-reducer Kocuria, an up-regulat

Integration of technological solutions aims to improve accuracy, precision and repeatability in farming operations, and biosensor devices are increasingly used for understanding basic biology during livestock production. The aim of this study was to design and validate a miniaturized tri-axial accelerometer for non-invasive monitoring of farmed fish with re-programmable schedule protocols.The device was attached to the operculum of gilthead sea bream and European sea bass juveniles for monitoring their physical activity by measurements of movement accelerations in x and y-axes, while records of operculum beats served as a measurement of respiratory frequency. Data post-processing of exercised fish in swimming test chambers revealed an exponential increase of fish accelerations with the increase of fish speed from 1 body-length to 4 body-lengths per second, while a close relationship between oxygen consumption and opercular frequency was consistently found.The usefulness of low computational load for data pre-processing with on-board algorithms was verified from low to submaximal exercise, increasing this procedure the autonomy of the system up to 6 h of data recording with different programmable schedules. Visual observations regarding tissue damage, feeding behavior and circulating levels of stress markers did not reveal at short term a negative impact of device tagging. Reduced plasma levels of triglycerides revealed a transient inhibition of feed intake in small fish, but this disturbance was not detected in larger fish. All this considered together is the proof of concept that miniaturized devices are suitable for non-invasive and reliable metabolic phenotyping of farmed fish to improve their overall performance and welfare. Further work is underway for improving the attachment procedure and the full device packaging., Comment: Preprint. Published on Frontiers in Physiology 29 May 2019 Sec. Aquatic Physiology Volume 10 - 2019 | https://doi.org/10.3389/fphys.2019.00667

The AEFishBIT tri-axial accelerometer was externally attached to the operculum to assess the divergent activity and respiratory patterns of two marine farmed fish, the gilthead sea bream (Sparus aurata) and European sea bass (Dicentrarchus labrax). Analysis of raw data from exercised fish highlighted the large amplitude of operculum aperture and body tail movements in European sea bass, which were overall more stable at low-medium exercise intensity levels. Cosinor analysis in free-swimming fish (on-board data processing) highlighted a pronounced daily rhythmicity of locomotor activity and respiratory frequency in both gilthead sea bream and European sea bass. Acrophases of activity and respiration were coupled in gilthead sea bream, acting feeding time (once daily at 11:00 h) as a main synchronizing factor. By contrast, locomotor activity and respiratory frequency were out of phase in European sea bass with activity acrophase on early morning and respiration acrophase on the afternoon. The daily range of activity and respiration variation was also higher in European sea bass, probably as part of the adaptation of this fish species to act as a fast swimming predator. In any case, lower locomotor activity and enhanced respiration were associated with larger body weight in both fish species. This agrees with the notion that selection for fast growth in farming conditions is accompanied by a lower activity profile, which may favor an efficient feed conversion for growth purposes. Therefore, the use of behavioral monitoring is becoming a reliable and large-scale promising tool for selecting more efficient farmed fish, allowing researchers and farmers to establish stricter criteria of welfare for more sustainable and ethical fish production.

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

Background Broodstock nutritional programming improves the offspring utilization of plant-based diets in gilthead sea bream through changes in hepatic metabolism. Attention was initially focused on fatty acid desaturases, but it can involve a wide range of processes that remain largely unexplored. How all this can be driven by a different genetic background is hardly underlined, and the present study aimed to assess how broodstock nutrition affects differentially the transcriptome and genome-wide DNA methylome of reference and genetically selected fish within the PROGENSA® selection program. Results After the stimulus phase with a low fish oil diet, two offspring subsets of each genetic background received a control or a FUTURE-based diet. This highlighted a different hepatic transcriptome (RNA-seq) and genome-wide DNA methylation (MBD-seq) pattern depending on the genetic background. The number of differentially expressed transcripts following the challenge phase varied from 323 in reference fish to 2,009 in genetically selected fish. The number of discriminant transcripts, and associated enriched functions, were also markedly higher in selected fish. Moreover, correlation analysis depicted a hyper-methylated and down-regulated gene expression state in selected fish with the FUTURE diet, whereas the opposite pattern appeared in reference fish. After filtering for highly represented functions in selected fish, 115 epigenetic markers were retrieved in this group. Among them, lipid metabolism genes (23) were the most reactive following ordering by fold-change in expression, rendering a final list of 10 top markers with a key role on hepatic lipogenesis and fatty acid metabolism (cd36, pitpna, cidea, fasn, g6pd, lipt1, scd1a, acsbg2, acsl14, acsbg2). Conclusions Gene expression profiles and methylation signatures were dependent on genetic background in our experimental model. Such assumption affected the magnitude, but also the type and direction of change. Thus, the r

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

[ES] La publicación de trabajos en revistas de reconocido impacto es uno de los puntales por los que se juzgan los méritos científicos. El sistema de publicación en Acceso Abierto impone a los autores unos costes de publicación que suelen sufragarse con partidas específicas de los proyectos financiados. Por tanto, a mayor productividad mayor gasto. En el caso de los investigadores del CSIC, desde la URICI se gestiona un sistema ágil y sencillo de apoyo para contribuir en todo o parte a estos desembolsos., [EN] Publication of papers in high-impact journals is one of the key points for the evaluation of scientific merits. The Open Access publication system claims publication charges to authors, that are usually taken from projects specific funding. So success in publication can lead to considerable costs. As a help for CSIC researchers, URICI manages an agile and simple support system to alleviate partially or even completely these publication charges.

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.

The present study aimed to evaluate the effect of dietary supplementation using bile salts (BSs) on several key performance indicators like growth and feed performance, fat accumulation and tissue condition in gilthead seabream (Sparus aurata). A 90-day feeding trial was conducted in juveniles of gilthead seabream (initial body weight, BW = 44.0 ± 4.2 g) that were fed three isoproteic (44% crude protein), isolipidic (18% crude fat) and isoenergetic (21.4 MJ kg−1) diets rich in saturated fats to favour lipid accumulation. One diet was used as a control and the others were supplemented with graded levels of a BS blend: 0.06 (BS0.06%) and 0.12% (BS0.12%). At the end of the trial, a significant increase in BW and a decrease in the levels of perivisceral fat were observed in fish fed the BS0.06% diet. However, only the BS0.12% diet significantly enhanced lipid digestibility, as indicated by the higher coefficient of apparent lipid digestibility and increased activity of the pancreatic bile salt-activated lipase. None of the diets modified the fatty acid profile of liver or fillet. In addition, while only the BS0.06% diet decreased fat deposits in liver, both BS-supplemented diets reduced fat accumulation in the intestine. Furthermore, dietary BS inclusion modified the bile acid profile in the gallbladder and anterior intestine, increasing the content of taurodeoxycholic acid in both tissues and decreasing the content of taurochenodeoxycholic acid in the gallbladder when supplementing the diet at an inclusion level of 0.12% of the BS blend. The gene expression profile of liver was analysed by quantitative PCR, targeting biomarkers mainly related to lipid metabolism and antioxidant defense, and few differences were found among dietary treatments. It was noteworthy that the decrease of lipoprotein lipase expression in fish fed the BS0.06% diet may be correlated with their reduced perivisceral fat and lipid accumulation in the liver, while the increase of the fatty acid synt

The GPRO suite is an in-progress bioinformatic project for -omics data analysis. As part of the continued growth of this project, we introduce a client- and server-side solution for comparative transcriptomics and analysis of variants. The client-side consists of two Java applications called “RNASeq” and “VariantSeq” to manage pipelines and workflows based on the most common command line interface tools for RNA-seq and Variant-seq analysis, respectively. As such, “RNASeq” and “VariantSeq” are coupled with a Linux server infrastructure (named GPRO Server-Side) that hosts all dependencies of each application (scripts, databases, and command line interface software). Implementation of the Server-Side requires a Linux operating system, PHP, SQL, Python, bash scripting, and third-party software. The GPRO Server-Side can be installed, via a Docker container, in the user’s PC under any operating system or on remote servers, as a cloud solution. “RNASeq” and “VariantSeq” are both available as desktop (RCP compilation) and web (RAP compilation) applications. Each application has two execution modes: a step-by-step mode enables each step of the workflow to be executed independently, and a pipeline mode allows all steps to be run sequentially. “RNASeq” and “VariantSeq” also feature an experimental, online support system called GENIE that consists of a virtual (chatbot) assistant and a pipeline jobs panel coupled with an expert system. The chatbot can troubleshoot issues with the usage of each tool, the pipeline jobs panel provides information about the status of each computational job executed in the GPRO Server-Side, while the expert system provides the user with a potential recommendation to identify or fix failed analyses. Our solution is a ready-to-use topic specific platform that combines the user-friendliness, robustness, and security of desktop software, with the efficiency of cloud/web applications to manage pipelines and workflows based on command line interface softw

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.

Given their role in lipid digestion, feed supplementation with bile salts could be an economic and sustainable solution to alterations in adiposity and intestinal inflammation generated by some strategies currently used in aquaculture. An important part of the metabolism of bile salts takes place in the intestine, where the microbiota transforms them into more toxic forms. Consequently, we aimed to evaluate the gut immune response and microbial populations in gilthead seabream (Sparus aurata) fed a diet supplemented with a blend of bile salts with proven background as a regulator of lipid metabolism and fat content. After the 90-day feeding trial, a differential modulation of the microbiota between the anterior and posterior intestine was observed. While in the anterior intestine the relative abundance of Desulfobacterota doubled, in the posterior intestine, the levels of Firmicutes increased and Proteobacteria, Actinobacteriota, and Campylobacterota were reduced when supplementing the diet with bile salts. Even so, only in the anterior intestine, there was a decrease in estimated richness (Chao1 and ACE indices) in presence of dietary bile salts. No significant differences were displayed in alpha (Shannon and Simpson indices) nor beta-diversity, showing that bile sales did not have a great impact on the intestinal microbiota. Regarding the gene expression profile in 2 h postprandial-fish, several changes were observed in the analyzed biomarkers of epithelial integrity, nutrient transport, mucus production, interleukins, cell markers, immunoglobulin production and pathogen recognition receptors. These results may indicate the development of an intestinal immune-protective status to tackle future threats. This work also suggests that this immune response is not only regulated by the presence of the dietary bile salts in the intestine, but also by the microbial populations that are in turn modulated by bile salts. After a fasting period of 2 days, the overall gene exp

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.

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 invention relates to a device placed on the operculum to monitor the metabolic state and well-being of fish through joint, simultaneous measurements of breathing frequency and physical activity via a plurality of accelerations that are coplanar (x and y axes) and normal to the operculum (z axis). The substrate is flexible and is covered with an water-resistant coating, which contains an electronic circuit with an acceleration sensor (208), a control unit (202), a microcontroller (206) configured to execute at least one activity-monitoring routine, a memory (210) and a battery (204). Data are collected via an external unit (201) which can optionally process them in a complete or partial manner. This type of measurement can be processed jointly with another type of measurement, obtained from other sensors of environmental parameters

[Introduction]: Studies in gilthead sea bream evidenced that high stocking densities exacerbate the negative impact of reduced oxygen availability, showing transcriptional analyses a different contribution of analyzed tissues (liver ≥ heart > muscle > blood) to the hypoxic- and crowding stress-mediated responses to cope with a changing environment (Martos-Sitcha et al., 2019). Moreover, blood metabolic and muscle transcriptomic landmarks indicate that mild hypoxia induces a hypometabolic state, increasing the contribution of lipid metabolism to the whole energy supply to preserve the aerobic energy production during exercise (Naya-Català et al., 2021a). The intestinal microbiota also has key effects on host health and welfare, and these complex populations tightly interact with the host affecting local and systemic physiological functions (Naya-Català et al., 2021b). Thus, the aim of the current study was to assess how mild hypoxia and high stocking rearing conditions affect the intestinal health of gilthead sea bream by applying a hologenomic approach to determine the host-microbiota interactions., [Methods]. Two-year-old gilthead sea bream (450-500 g) were tagged and distributed in 3,000 L tanks to achieve three different initial rearing densities (low, LD: 6 kg/m3; medium, MD: 12 kg/m3; high, HD: 22 kg/m3). Fish were fed close to satiety with a commercial diet from May to June (8 weeks) under natural photoperiod and temperature conditions at our latitude (40°5’N;0°10’E), varying the concentration of dissolved oxygen from 6-5 ppm in LD fish to 5-4 ppm in MD fish, and 4-3 ppm in HD fish. At the end of the trial, the growth rate of HD fish was 40% lower than that of MD/LD fish, and randomly selected fish from each group were taken to obtain tissue and mucus samples from the anterior intestine. RNA extracted from the anterior intestine from 10 fish/group was sequenced using NovaSeq PE150 (50 M reads/sample), and reads were assembled and mapped against the gilthead sea bream genome. DESeq2 was used to extract genes with P < 0.05 in all comparisons, that were used to perform discriminant and cluster analysis to determine the number of differentially expressed genes among conditions. K-means, GO and KEGG enrichment analyses were subsequently performed. The V3V4 regions of the 16S rRNA of the mucus DNA samples from the same animals were amplified and sequenced by Illumina MiSeq. After quality filtering, taxonomic assignment was performed with a custom-made pipeline using the RDP database. Alpha diversity was calculated using Phyloseq and beta diversity using PERMANOVA and PLS-DA models. Correlations between differentially expressed genes and discriminant bacteria were studied using the corrplot R package., [Results]: RNAseq and discriminant analyses revealed that a total of 2,813 differentially expressed genes significantly separated the three groups (Fig. 1A). K-means analysis divided these genes into four different clusters according to their expression patterns in each group, separating one cluster of 800 genes with higher expression in LD, a second cluster of 1,103 genes with higher expression in MD, a third cluster of 688 genes with higher expression in HD, and a fourth cluster of 222 genes that gradually increased expression with the stocking density (LD

Bile salts (BSs) are a proven asset as a dietary additive in some fish species, due to their positive effects on growth, feed utilization, lipid digestibility, oxidative status and lipid metabolism. In higher vertebrates, it has been demonstrated that these molecules shape the gut microbiota by having an antimicrobial effect, while some bacteria can metabolize them into secondary BSs that are non-toxic to the microbiota and have a key role in lipid metabolism. In addition, it has been suggested that the BS-receptor farnesoid X receptor (FXR), could act as a modulator of innate intestinal immunity. On the other hand, BSs alterations in the host's BS profile can create microbial dysbiosis associated with intestinal diseases, which could jeopardize the potential role of BSs as additives. Due to the existence of a gap in the knowledge about the effect of BSs on the immune response and the gut microbiota in teleosts, we intend in this work not only to verify the effect of BS dietary supplementation on growth and feeding performance, somatic indices and apparent digestibility coefficients, but mainly to study how these molecules affect the BS profile, the gut microbiota and the intestinal expression profile in gilthead seabream (Sparus aurata). For this purpose, juveniles with an initial body weight (BWi) of 44 ± 4 g were fed during 90 days with two isoproteic (44.0%), isolipidic (22.6%) and isoenergetic (21.4 MJ/kg) high-saturated fat diets, one of them as a control, and the other supplemented with a concentration of 0.06 % of a blend of BSs (cholic acid sodium salt, deoxycholic acid sodium salt and sodium taurocholate). At the end of the trial, fish fed the BS diet were heavier (BWf = 221.21 ± 3.10 g), longer (SLf = 19.65 ± 0.10 cm), showed a higher specific growth rate (SGR = 1.83 ± 0.02% day-1) and lower perivisceral fat index (PFI = 2.58 ± 0.19%) with respect to the control group (BWf = 215.80 ± 1.06 g, SLf = 19.32 ± 0.21 cm, SGR = 1.81 ± 0.01% day-1, PFI = 3.01 ± 0.

The use of body adiposity modulators, such as bile salts, as feed additives could be a good nutritional strategy to avoid adiposity disorders in fish, which may be attributed to their beneficial role in promoting lipid metabolism and enhancing fat digestibility. Furthermore, bile salts have a key role in the regulation of the gut microbiota, which has also been shown to modulate fat accumulation in higher vertebrates. In this context, we aimed to test the effect of supplementing high-saturated fat diets with bile salts on growth performance, feed utilization, lipid digestibility, fat accumulation, bile acids profile, gene expression related to lipid metabolism, and gut microbiome in Sparus aurata. For this purpose, seabream juveniles (44.1 ± 4.1 g) were fed during 90 days with three isoproteic (44 %), isolipidic (22.6 %) and isoenergetic (21.4 MJ/kg) high-saturated fat diets, supplemented with increasing concentrations (0, 0.06 and 0.12 %) of bile salts (BS; sodium taurocholate and deoxycholic acid). Results showed that fish fed BS-supplemented diets showed an improvement in growth, being the fish fed with the diet supplemented with 0.06 and 0.12 % a 2.4 and a 2.1 % heavier than the control group, respectively. In addition, the level of perivisceral adiposity was reduced in fish fed BS diets compared to the control. These results were in accordance with the lower levels of hepatic and intestinal fat deposits observed under histological examination in fish fed the diets with an inclusion of 0.06% of BS. Proximate composition of liver and fillet were also evaluated, and yttrium oxide was included in the diets as an inert marker for proper determination of apparent digestibility coefficients for macronutrients. Bile acids profiles were examined in fasting gallbladder and in the gut of fed animals. Based on the above, hepatic gene expression of several markers associated with lipid and energy metabolism, and the gut microbiome were studied in fish fed with the 0.06% BS

The present study aimed to unravel the effects of partial (50%; 50LSAqua) and total (100%; 100LSAqua) replacement of fish meal (FM) by a commercial protein source (LSAqua SusPro) made of bacterial and processed animal proteins (PAP) in farmed juveniles of gilthead sea bream (Sparus aurata). The trial lasted 8 weeks, and the feasibility of replacement was assessed in terms of growth performance, histopathological scoring and composition of mucosal adherent microbiota from anterior intestine (AI). Specific growth rates (SGR) of 50LSAqua fish were undistinguishable from the CTRL group, whereas a slight but significant growth impairment was found with the total replacement. Histological signs of inflammation across the intestine were more evident at the highest level of FM replacement. Illumina sequencing of gut mucosal microbiota yielded a mean of 130,439 reads per sample assigned to 1,567 OTUs at 97% identity threshold. The bacterial richness was similar in all groups, but a significantly higher Simpson diversity index was found in 100LSAqua fish. At the phylum level, Proteobacteria were the most abundant in all groups, whereas Firmicutes decreased and Actinobacteria increased with the FM replacement. The inferred metagenome analysis suggested that these discriminant bacteria could be implicated in a counter-regulatory anti-inflammatory response. It also pointed to an over-representation of mucosal microbes that can potentially be involved in the natural production of antimicrobials in fish fed the experimental diets.

Growth is one of the most desirable traits in an aquaculture species, which is in turn closely related to early maturity, a complex biological process that reduces the final yield of fish farming operations. Thus, while the selection of rapid-growth fish is highly attractive for the aquaculture sector, it is also common to select against early-maturing fish. The correlation between body size and age at maturation is still not entirely understood in fish, and several studies have reported different associations between the two traits. In this study, biometric and physiological parameters are being evaluated in order to determine the relationship of small and large sized female sea bass and its ovarian growth. Fish were individually tagged and growth and gonadal development were evaluated during the second and third year of age. Fish have been sacrificed at the end of each sexual cycle and performance indicators are being restored to specific point-in time based on the oocyte development. Temporal hormonal profiles, including Fsh, sex steroids, vitellogenin and Igf-1 plasma levels are being determined. Furthermore, genes with a putative role in the relationship between both growth and reproductive systems will be analysed. Results show the existence of early differential growth within the female sea bass. Thus, slow- (small-sized) and fast- (large-sized) growing female sea bass have been identified and their relationship to gonadal maturity has been considered. We have identified four female phenotypes as follows: a) small-sized and immature gonads, b) small-sized and maturing gonads, c) large-sized and immature gonads and d) large-sized and maturing gonads, over the second and third sexual cycles of this species. Accordingly, physiological aspects and also molecular factors are being considered to elucidate key events contributing to the relationship between these traits. A comprehensive understanding of the relationship between growth and maturation in sea bass will

Aquaculture is a sector with a rapid growth and a great potential to provide healthy and sustainable protein for future generations. In this context, and with stricter criteria of farmed animal welfare, it is very important to monitor fish behavior for the simultaneous improvement of the productivity and the welfare of group-housed animals. In the framework of AQUAEXCEL2020 EU project we have developed an ultra-low-power, stand-alone, miniature microsystem (AEFishBIT) with the double aim to combine measurements of physical and metabolic activities. The system was developed using available technology and includes a triaxial accelerometer and a microcontroller packaged in a waterproof container. It has been designed to be externally implanted on fish operculum and by signal filtering, it allows the measurements of physical activity and respiratory frequency.

To meet the increasing global demand of fish protein, aquaculture production is becoming more intensified, which requires the selection of non-aggressive individuals that perform well at high densities. Indeed, fish with high stress resilience are less susceptible to diseases, show better growth performance, and provide a better-quality product. In the other hand, animal health and welfare issues are of increasing public concern, and livestock industries and aquaculture in particular require to project a welfare-friendly image of their products. It is thereby important to encompass the development of aquaculture with novel and stricter criteria of welfare for the simultaneous improvement of the productivity and the welfare of group-housed animals. With the advent of new technologies, it is becoming relatively easy to integrate insights from the environment, microbial loads, and fish behaviour and appearance. Behavioural indicators are becoming especially useful for alerting farmers that something is potentially wrong before significant welfare issues and mortality occur. The challenge is that very often behavioural indicators are difficult to quantify in the aquatic environment and proper assessment of fish welfare often requires additional physiological measurements. Moreover, these analysis becomes tedious and laborious. Therefore, to turn quantitative behavioural analysis into practical operational welfare indicators, technological advances on machine vision, biotelemetry and miniaturized bio-loggers need to be applied and adapted to the demand of fish welfare monitoring. The above reasons led to the design of AEFishBIT, a small data storage Tag for a reliable underscore of welfare in fish exposed to different aquaculture stressors. This device was designed and validated for the individual and simultaneous monitoring of physical activity and gill ventilation rates (two in one). This improvement in fish sensing is intended to contribute to associate different acti

This study aimed to highlight the relationship between diet, animal performance and mucosal adherent gut microbiota (anterior intestine) in fish fed plant-based diets supplemented with an egg white hydrolysate (EWH) with antioxidant and antiobesogenic activity in obese rats. The feeding trial with juveniles of gilthead sea bream (Sparus aurata) lasted 8 weeks. Fish were fed near to visual satiety with a fish meal (FM)/fish oil (FO) based diet (CTRL) or a plant-based diet with/without EWH supplementation. Specific growth rate decreased gradually from 2.16% in CTRL fish to 1.88% in EWH fish due to a reduced feed intake, and a slight impairment of feed conversion ratio. Plant-based diets feeding triggered a hyperplasic inflammation of the anterior intestine regardless of EWH supplementation.

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 present study aimed to unravel the effects of partial (50%; 50LSAqua) and total (100%; 100LSAqua) replacement of fish meal (FM) by a commercial protein source (LSAqua SusPro) made of bacterial and processed animal proteins (PAP) in farmed juveniles of gilthead sea bream (Sparus aurata). The trial lasted 8 weeks, and the feasibility of replacement was assessed in terms of growth performance, histopathological scoring and composition of mucosal adherent microbiota from anterior intestine (AI). Specific growth rates (SGR) of 50LSAqua fish were undistinguishable from the CTRL group, whereas a slight but significant growth impairment was found with the total replacement. Histological signs of inflammation across the intestine were more evident at the highest level of FM replacement, and the total concentration of short chain fatty acids (SCFA) in stripped feces decreased in a dose dependent manner. Illumina sequencing of gut mucosal microbiota yielded a mean of 130,439 reads per sample assigned to 1,567 OTUs at 97% identity threshold. The bacterial richness was similar in all groups, but a significantly higher Simpson diversity index was found in 100LSAqua fish. At the phylum level, Proteobacteria were the most abundant in all groups, whereas Firmicutes decreased and Actinobacteria increased with the FM replacement. At a closer look, pro-inflammatory Gammaproteobacteria of the genus Psychrobacter, and Acinetobacter decreased with FM replacement, whereas the anti-inflammatory Paracoccus, Arthrobacter, and Actinomycetales increased, with a remarkable presence of the Propioniciclava genus in LSAqua groups. The inferred metagenome analysis suggested that these discriminant bacteria could be implicated in a counter-regulatory anti-inflammatory response. It also pointed to an over-representation of mucosal microbes that can potentially be involved in the natural production of antimicrobials in fish fed the experimental diets.

Behavioral parameters are reliable and useful operational welfare indicators that yield information on fish health and welfare status in aquaculture. However, aquatic environment is still constraining for some solutions based on underwater cameras or echo sounder transmitters. Thus, the use of bio-loggers internally or externally attached to sentinel fish emerges as a solution for fish welfare monitoring in tanks- and sea cages-rearing systems. This review is focused on the recently developed AEFishBIT, a small and light data storage tag designed to be externally attached to fish operculum for individual and simultaneous monitoring of swimming activity and ventilation rates under steady and unsteady swimming conditions for short-term periods. AEFishBIT is a tri-axial accelerometer with a frequency sampling of 50¿100 Hz that is able to provide proxy measurements of physical and metabolic activities validated by video recording, exercise tests in swim tunnel respirometers, and differential operculum and body tail movements across fish species with differences in swimming capabilities. Tagging procedures based on tag piercing and surgery procedures are adapted to species anatomical head and operculum features, which allowed trained operators to quickly complete the tagging procedure with a fast post-tagging recovery of just 2.5¿7 h in both salmonid (rainbow trout, Atlantic salmon) and non-salmonid (gilthead sea bream, European sea bass) farmed fish. Dual recorded data are processed by on-board algorithms, providing valuable information on adaptive behavior through the productive cycle with the changing environment and genetics. Such biosensing approach also provides valuable information on social behavior in terms of adaptive capacities or changes in daily or seasonal activity, linking respiratory rates with changes in metabolic rates and energy partitioning between growth and physical activity. At short-term, upcoming improvements in device design and accompanying sof

Fish genetically selected for growth (GS) and reference (REF) fish were fed with CTRL (15% FM, 5–7% FO) or FUTURE (7.5% FM, 10% poultry meal, 2.2% poultry oil + 2.5% DHA-algae oil) diets during a 12-months production cycle. Samples from initial (t0; November 2019), intermediate (t1; July 2020) and final (t2; November 2020) sampling points were used for Illumina 16S rRNA gene amplicon sequencing of the adherent microbiota of anterior intestine (AI). Samples from the same individuals (t1) were also used for the gene expression profiling of AI by RNA-seq, and subsequent correlation analyses with microbiota abundances. Discriminant analyses indicated the gut bacterial succession along the production cycle with the proliferation of some valuable taxa for facing seasonality and different developmental stages. An effect of genetic background was evidenced along time, decreasing through the progression of the trial, namely the gut microbiota of GS fish was less influenced by changes in diet composition. At the same time, these fish showed wider transcriptomic landmarks in the AI to cope with these changes. Our results highlighted an enhanced intestinal sphingolipid and phospholipid metabolism, epithelial turnover and intestinal motility in GS fish, which would favour their improved performance despite the lack of association with changes in gut microbiota composition. Furthermore, in GS fish, correlation analyses supported the involvement of different taxa with the down-regulated expression of pro-inflammatory markers and the boosting of markers of extracellular remodelling and response to bacterium. Altogether, these findings support the combined action of the gut microbiome and host transcriptionally mediated effects to preserve and improve gut health and function in a scenario of different growth performance and potentiality.

The use of feed additives has expanded rapidly as an alternative for antibiotics and chemotherapeutics, with also the capacity to modify the composition of gut microbiota. In farmed fish, and in gilthead sea bream in particular, there is evidence that the host genetic background has a major impact on gut microbiota. Thus, families selected for fast growth have a more flexible microbiota capable of exerting a wider nutritionallymediated response with less microbial community changes. However, nutrition and genetic interactions remain poorly explored in fish, and the aim of this study was to unravel how the microbiota of fish selected (GS) and unselected (NGS) for growth is differentially regulated by oil-coated feed additives. The basal diet (CTRL, no feed additives) was a low fish meal/fish containing algae oil, poultry by-products, and plant ingredients. Experimental diets were oil-coated with the additives: organic acids (OA), Bacillus-species probiotics (PROB), or natural plant extracts (PHYTO). Fish were fed to visual satiety with the CTRL diet during two weeks. After this adaptation period, the different supplemented diets were used with a high additive dose (7.5-10 g/kg) during 2 weeks, decreasing thereafter to 2-5 g/kg until the end of the trial (97 days). Then, adherent microbiota was obtained from the anterior intestine. Illumina sequencing of microbiota yielded a mean of 62,594 reads per sample, which were assigned to 1,156 OTUs at 97% identity threshold. A significant lower richness and diversity was found in the GS fish, which was mainly evidenced by a higher abundance of Actinobacteria in GS-PROB. To study in more detail the observed differences on gut microbial populations, supervised partial least-squares discriminant analyses (PLS-DA) were used. When all populations were analysed as a whole (GS vs NGS), dispersal was markedly lower in GS fish. This pattern was further evidenced for fish fed the CTRL, PROB and OA diets but not for the PHYTO additive

In parallel with the growth of the aquaculture industry, an increasing interest in fish microbiota research has grown to improve fish welfare and nutrition, as it plays a critical role in protection against pathogens, nutrient digestion and absorption, excretion of nitrogenous wastes, and osmotic regulation. Thus, the characterization of microbial communities is pivotal for detecting potential alterations that lead to fish homeostatic imbalance. During intensive fish farming, high rearing densities can be achieved, and this can dramatically reduce water oxygen availability, especially with the summer increase of temperature. This study aimed to assess how mild hypoxia and relatively high stocking densities affect gilthead sea bream skin microbiota, and how these results could correlate with different operational welfare indicators (OWIs), in order to improve fish health and aquaculture productivity. Hereby, two-year-old gilthead sea bream (450-500 g) were tagged and distributed in 3,000 L tanks to achieve three different initial rearing densities (low, LD: 6 kg/m3; medium, MD: 12 kg/m3, high, HD: 22 kg/m3). Fish were fed close to satiety with a commercial diet from May to June (8 weeks) under natural photoperiod and temperature conditions at our latitude (40°5’N;0°10’E), varying the concentration of dissolved oxygen from 6-5 ppm in LD fish to 5-4 ppm in MD fish, and 4-3 ppm in HD fish. At the end of the trial, growth rates of HD fish were 40% lower in comparison to MD/LD fish. At this stage, randomly selected fish (12 fish per group) were evaluated for external tissue OWIs, using a scoring system from 1 to 5, which detected different levels of fin damage and skin epidermal lesions in HD fish and to a lower extent in MD fish. The same fish were used to obtain skin mucus samples for microbiota analysis, the 16S rRNA v1-v9 regions were sequenced with the Oxford Nanopore Technology (ONT) MinION device, and then processed with an in-house bioinformatics pipeline to analy

The gut microbiota is now recognised as a key target for improving aquaculture profit and sustainability, but we still lack insights into the activity of microbes in fish mucosal surfaces. In the present study, a metatranscriptomic approach was used to reveal the expression of gut microbial genes in the farmed gilthead sea bream. Archaeal and viral transcripts were a minority but, interestingly and contrary to rRNA amplicon-based studies, fungal transcripts were as abundant as bacterial ones, and increased in fish fed a plant-enriched diet. This dietary intervention also drove a differential metatranscriptome in fish selected for fast and slow growth. Such differential response reinforced the results of previously inferred metabolic pathways, enlarging, at the same time, the catalogue of microbial functions in the intestine. Accordingly, vitamin and amino acid metabolism, and rhythmic and symbiotic processes were mostly shaped by bacteria, whereas fungi were more specifically configuring the host immune, digestive, or endocrine processes.

The exponential growth of the aquaculture sector requires the development of sustainable aquafeeds with less dependence on marine products. The maximized replacement of fish meal (FM) and fish oil (FO) with plant ingredients has been extensively studied in the economically important species gilthead sea bream (Sparus aurata). Recently, major progress has been done with other alternative raw materials, though some non-pathological inflammatory response persisted with feed formulations that increased the circularity of resource utilization. In the present study, we evaluated the effects on growth performance, gene expression, intestinal microbiota and disease resistance of a FM-free diet (NoPAP SANA), based on plant ingredients, aquaculture by-products, algae oil, insect meal and bacterial fermentation biomasses as main dietary oil and protein sources, and supplemented with a commercially available health-promoting feed additive (SANACORE®GM). Juveniles of 21 g initial body weight were fed control or NoPAP SANA diets for 34 days, and head kidney, liver and posterior intestine were collected for gene expression analyses using customized PCR-arrays. Each tissue-specific PCR covered 96 genes in total and included markers of growth performance, lipid and energy metabolism, antioxidant defence, immune system, and intestinal function and integrity. From the same fish, the adherent bacteria of the posterior intestine were studied by Illumina sequencing of the V3-V4 region of the 16S rRNA. The remaining fish were challenged with the intestinal parasite Enteromyxum leei for 78 days and sampled for parasite diagnosis. Both control and NoPAP SANA fish grew efficiently considering gilthead sea bream standards. Before parasite challenge, the NoPAP SANA group showed differential expression of 17, 2 and 4 genes in liver, head kidney and posterior intestine, respectively. The intestinal bacterial composition showed no major differences in diversity or at the phylum level. However, 29

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.

Integration of technological solutions aims to improve accuracy, precision and repeatability in farming operations, and biosensor devices are increasingly used for understanding basic biology during livestock production. The aim of this study was to design and validate a miniaturized tri-axial accelerometer for non-invasive monitoring of farmed fish with re-programmable schedule protocols. The current device (AE-FishBIT v.1s) is a small (14 mm × 7 mm × 7 mm), stand-alone system with a total mass of 600 mg, which allows monitoring animals from 30 to 35 g onwards. The device was attached to the operculum of gilthead sea bream (Sparus aurata) and European sea bass (Dicentrarchus labrax) juveniles for monitoring their physical activity by measurements of movement accelerations in x- and y-axes, while records of operculum beats (z-axis) served as a measurement of respiratory frequency. Data post-processing of exercised fish in swimming test chambers revealed an exponential increase of fish accelerations with the increase of fish speed from 1 body-length to 4 body-lengths per second, while a close relationship between oxygen consumption (MO2) and opercular frequency was consistently found. Preliminary tests in free-swimming fish kept in rearing tanks also showed that device data recording was able to detect changes in daily fish activity. The usefulness of low computational load for data pre-processing with on-board algorithms was verified from low to submaximal exercise, increasing this procedure the autonomy of the system up to 6 h of data recording with different programmable schedules. Visual observations regarding tissue damage, feeding behavior and circulating levels of stress markers (cortisol, glucose, and lactate) did not reveal at short term a negative impact of device tagging. Reduced plasma levels of triglycerides revealed a transient inhibition of feed intake in small fish (sea bream 50–90 g, sea bass 100–200 g), but this disturbance was not detected in large

Dispositivo emplazado en el opérculo para supervisar el estado metabólico y bienestar de peces a través de medidas conjuntas y simultáneas de frecuencia respiratoria y actividad física mediante una pluralidad de aceleraciones coplanares (ejes x,y) y normales al opérculo (eje z). El sustrato es flexible y está cubierto con un revestimiento impermeable, donde se encuentra un circuito electrónico con sensor de aceleración (208), una unidad de control (202), un microcontrolador (206) configurado para ejecutar al menos una rutina de monitorización de actividad, una memoria (210) y una batería (204). La toma de datos se efectúa a través de una unidad externa (201) que eventualmente puede procesarlos de forma total o parcial. Este tipo de mediciones se pueden procesar de forma conjunta con otro tipo de medidas, obtenidas a partir de otros sensores de parámetros medio-ambientales

Dispositivo emplazado en el opérculo para supervisar el estado metabólico y bienestar de peces a través de medidas conjuntas y simultáneas de frecuencia respiratoria y actividad física mediante una pluralidad de aceleraciones coplanares (ejes x,y) y normales al opérculo (eje z). El sustrato es flexible y está cubierto con un revestimiento impermeable, donde se encuentra un circuito electrónico con sensor de aceleración (208), una unidad de control (202), un microcontrolador (206) configurado para ejecutar al menos una rutina de monitorización de actividad, una memoria (210) y una batería (204). La toma de datos se efectúa a través de una unidad externa (201) que eventualmente puede procesarlos de forma total o parcial. Este tipo de mediciones se pueden procesar de forma conjunta con otro tipo de medidas, obtenidas a partir de otros sensores de parámetros medio-ambientales

[EN] The invention relates to a device placed on the gill cover to monitor the metabolic state and well-being of fish through joint, simultaneous measurements of breathing frequency and physical activity via a plurality of accelerations that are coplanar (x and y axes) and normal to the gill cover (z axis). The substrate is flexible and is covered with an impervious coating, which contains an electronic circuit with an acceleration sensor (208), a control unit (202), a microcontroller (206) configured to execute at least one activity-monitoring routine, a memory (210) and a battery (204). Data are collected via an external unit (201) which can optionally process them in a complete or partial manner. This type of measurement can be processed jointly with another type of measurement, obtained from other sensors of environmental parameters, [ES] Dispositivo emplazado en el opérculo para supervisar el estado metabólico y bienestar de peces a través de medidas conjuntas y simultáneas de frecuencia respiratoria y actividad física mediante una pluralidad de aceleraciones coplanares (ejes x,y) y normales al opérculo (eje z). El sustrato es flexible y está cubierto con un revestimiento impermeable, donde se encuentra un circuito electrónico con sensor de aceleración (208), una unidad de control (202), un microcontrolador (206) configurado para ejecutar al menos una rutina de monitorización de actividad, una memoria (210) y una batería (204). La toma de datos se efectúa a través de una unidad externa (201) que eventualmente puede procesarlos de forma total o parcial. Este tipo de mediciones se pueden procesar de forma conjunta con otro tipo de medidas, obtenidas a partir de otros sensores de parámetros medio-ambientales, [FR] La présente invention concerne un dispositif mis en place sur l'opercule pour surveiller l'état métabolique et le bien-être de poissons au moyen de mesures conjointes et simultanées de la fréquence respiratoire et de l'activité physique avec une pluralité d'accélérations coplanaires (axes x,y) et perpendiculaires à l'opercule (axe z). Le substrat est flexible et couvert d'un revêtement imperméable, où se situe un circuit électronique avec capteur d'accélération (208), une unité de commande (202), un microcontrôleur (206) configuré pour exécuter au moins une routine de surveillance d'activité, une mémoire (210) et une batterie (204). La capture de données est effectuée au moyen d'une unité externe (201) qui peut éventuellement les traiter de manière complète ou partielle. Les mesures de ce type peuvent être traitées de manière conjointe avec un autre type de mesures, obtenues à partir d'autres capteurs de paramètres du milieu ambiant

The GH/IGF-I system is the main endocrine regulator of growth in vertebrates. But, how correlated is the pituitary expression of GH and that of the other components of the system with the animal growth condition? To answer this we have analyzed the changes on pituitary GH and related molecules expression upon different experimental conditions in vivo and in vitro in gilthead sea bream (Sparus aurata). Gilthead sea bream juveniles were treated with recombinant bovine GH (rbGH, Posilac), were fasted during 21 days and refed for 7 days, or were fed a diet containing an amino acid (AA) derivative. Moreover, adult fish pituitaries were treated in vitro with different hormones and AA. Pituitary GH expression in rbGH-treated fish was down-regulated reaching the lowest values after 6 weeks of injection and maintaining low levels during the rest of the experiment, suggesting that sustained high levels of exogenous GH provoked a clear depression on GH synthesis and secretion. On the contrary, 21-days fasting triggered an increase of pituitary GH expression parallel to plasma levels, while GH and IGF-I receptors expression strongly decreased, and refeeding partially recovered the basal levels. The adaptation to food deprivation determined a simultaneous increase of GH gene and protein expression to facilitate its energy mobilization function. Dietary supplementation for 8 weeks with an AA derivative also provoked a tendency to increase GH expression. Finally, hemi-pituitaries treated with Ghrelin or the AA Lysine and Leucine increased, while IGF-I or Somatostatin decreased GH expression. In summary, considering the difficulties to analyze GH circulating levels, these results indicate that pituitary GH expression can be a useful parameter to understand the effects of different physiological conditions on GH/IGF-I system in fish

We report a draft genome assembly for the teleost gilthead sea bream (Sparus aurata), reconstructed by combination of short- and long-read high-throughput sequencing, and genetic linkage maps. The assembly comprised 5,039 scaffolds that span 1.24 Gb of the expected 1.59 Gb complete genome size, with 932 scaffolds (~732 Mb) anchored to 24 chromosomes. This sequencing strategy resulted in a high quality fish genome assembly, as supported by the high N50 (1.07 Mb) and lower L50 (227) values. These long and continuous reads allowed the annotation of a large number of coding genes (55,423), non-coding RNA genes (2,991) and 345 Mb of mobile genetic elements. Synteny analysis revealed a high level of homology between gilthead sea bream genes. Phylogenomics relationships with other fish species were established to locate temporal speciation and to assign duplication events. A large degree of recent and lineage-specific gene duplications were found, that were mainly enriched in functions related to genome transposition, immune response and response to stimulus. These duplication and gene family expansions could be related in part to the activity of mobile genetic elements. This fact makes gilthead sea bream an interesting model for the study of gene repertoire expansion strategies complementary to fish whole genome duplication events. Transcriptional analyses across six different tissues (anterior and posterior intestine, skeletal muscle, liver, gills, spleen) indicated that gene duplication preferentially affected genes expressed in two or more tissues. These findings highlight the genomic complexity of this species and the importance of selective gene duplications in the adaptation of fishes to challenging environment.

Sirtuins (SIRTs) are a conserved family of enzymes that couple protein deacetylation of histone and non-histone substrates with the energy status of the cell via the cellular NAD+/NADH ratio. This protein family has been largely conserved through evolution, and the SIRT counterparts of higher vertebrates have been identified and molecularly characterized in gilthead sea bream (Simó-Mirabet et al., 2017). Transcriptional studies have also revealed a ubiquitous sirt gene expression that is tissue-specific for each sirt and highly dependent on feed intake and growth potentiality (Simó-Mirabet et al., 2017, 2018). This agrees with an epigenetic role of SIRT related with developmental, differentiation and genome environment interactions. Nevertheless, there are few studies assessing the DNA methylation pattern of SIRT promoters, and the aim of this study was to determine if changes of sirt gene expression in liver and white skeletal muscle of one- and three-year old fish during winter and summer are due, at least in part, to changes in DNA methylation of sirt promoters. The study also included the gene expression profilingof markers of oxidative metabolism (cs, cpt1a, pgc1a) and mitochondrial respiration uncoupling (ucp1, ucp3). The exon-intron organization of the seven gilthead seabream sirts was determined by blat searches in our genomic gilthead sea bream database (http://nutrigroup-iats.org/seabreamdb). This in silico analysis included predictions of transcription start sites (TSS), core promoter regions, transcription factor binding sites (TFBS) and CpG islands (CGIs). For transcriptional and DNA methylation assays, tissue portions of liver and white skeletal muscle were processed for RNA and DNA extraction in fish of two class of age (+1, +3) at two different times (winter, February 2018; summer, June 2018). DNA methylation was examined by bisulfite conversion and pyrosequencing of CGIs close to TSS of sirt1 (22 CpG sites) and sirt3 (4 CpG sites). Gene expression p

With the use of electronic tracking technology, data on fish movements, physiology and environmental parameters can be collected from each tagged individual. The perfect tag - small size, lasting activity, long distance data transmission (e.g. radiotransmitters, acoustic transmitters, pop-up satellite archival tags) - does not exist, and the choice of telemetry technology and tagging method (external, intracelomic, intragastric) depends on fish species, life stage and research question. The proposed solution within the AQUAEXCEL2020 EU project is a stand-alone, small and light (1 g) device (AEFishBIT), composed of a tri-axial accelerometer, a microprocessor, a battery and an RFID tag for quick-smart identification. The device is externally attached to the operculum to monitor physical activity by mapping accelerations in x- and y-axes, while operculum beats (z-axis) serve as a measurement of respiratory frequency. Initial functional validation has been made with gilthead sea bream and European sea bass juveniles in swimming test chambers, highlighting a high correlation of oxygen consumption and swimming activity with the calculated AEFishBIT records (MartosSitcha et al., 2019; Frontiers in Physiology 10:667). Current studies with free-swimming fish reveal that the attachment protocol does not have a negative impact on growth performance in active feeding fish, offering a wide range of new information based on individual behaviour: i) the switch from nocturnal to diurnal rhythms of activity across season, ii) the different energy partitioning for growth and maintenance, iii) the asynchrony of movements as an indirect measure of aging and adaptability to culture environment, and iv) the different coping behaviour of fish challenged with low water oxygen concentrations. AEFishBIT also provides reliable information of disease outcome in fish parasitized with the intestinal myxozoan Enteromyxum leei, emerging as the ideal complement for sensing the quality of the enviro