Gene expression profiling reveals functional specialization along the intestinal tract of a carnivorous teleostean fish (Dicentrarchus labrax)

High-quality sequencing reads from the intestine of European sea bass were assembled, annotated by similarity against protein reference databases and combined with nucleotide sequences from public and private databases. After redundancy filtering, 24,906 non-redundant annotated sequences encoding 15,367 different gene descriptions were obtained. These annotated sequences were used to design a custom, high-density oligo-microarray (8 × 15 K) for the transcriptomic profiling of anterior (AI), middle (MI), and posterior (PI) intestinal segments. Similar molecular signatures were found for AI and MI segments, which were combined in a single group (AI-MI) whereas the PI outstood separately, with more than 1900 differentially expressed genes with a fold-change cutoff of 2. Functional analysis revealed that molecular and cellular functions related to feed digestion and nutrient absorption and transport were over-represented in AI-MI segments. By contrast, the initiation and establishment of immune defense mechanisms became especially relevant in PI, although the microarray expression profiling validated by qPCR indicated that these functional changes are gradual from anterior to posterior intestinal segments. This functional divergence occurred in association with spatial transcriptional changes in nutrient transporters and the mucosal chemosensing system via G protein-coupled receptors. These findings contribute to identify key indicators of gut functions and to compare different fish feeding strategies and immune defense mechanisms acquired along the evolution of teleosts.This work was funded by the EU seventh Framework Programme by the ARRAINA (Advanced Research Initiatives for Nutrition and Aquaculture; KBBE-2011-288925) project. It does not necessarily reflect the views of the EU and in no way anticipates the Commission's future policy in this area. The funders had no role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript. Additional funding was obtained from the Spanish Ministerio de Economía y Competitividad through the MI2-FISH project (Unraveling Metabolic, Intestinal and Immunopathological Fish Status; AGL2013-48560) and Generalitat Valenciana (PROMETEO FASE II-2014/085).Peer Reviewe

Wide-targeted gene expression infers tissue-specific molecular signatures of lipid metabolism in fed and fasted fish

European sea bass (Dicentrarchus labrax) is one of the most important species for Mediterranean aquaculture. It is therefore crucial to establish appropriate feeding management regimens and to gain better knowledge of nutritional requirements for this species, exploring not only new feed ingredients and feeding strategies, but also understanding the molecular mechanisms that regulate the metabolism of nutrients. Accordingly, transcriptomic analysis represents a useful nutrigenomic discovery tool for identifying the molecular basis of biological responses to nutrition as well as nutritional biomarkers in fish. This study evaluated how the transcriptional activity of genes controlling lipid metabolism in European sea bass were modulated in a tissue-specific manner in response to fasting and refeeding. Such approach focused on a panel of 29 genes in which desaturases, elongases, triacylglycerol lipases, fatty acid-binding proteins, β-oxidation and oxidative phosphorylation enzymes, phospholipid-related enzymes, and transcription factors that regulate lipid homeostasis were represented. Fasting activated the lipolytic machinery in adipose tissue, liver and muscle of European sea bass, whereas markers of lipogenesis were downregulated in liver and adipose tissue. Genes involved in phospholipid and oxidative metabolism were differentially regulated in liver and skeletal muscle of fasted European sea bass. However, 12 days of refeeding were sufficient, for the most part, to reverse the expression of key genes. Overall, our data clearly showed a tissue-specific regulation of lipid-related genes according to the different metabolic capabilities of each tissue, being the brain the most refractory organ to changes in nutrient and energy availability and liver the most responsive tissue.This research was partly funded by AQUAEXCEL EU 7 FP Project (Grant Agreement 262336): Trans National Access Grant to S.R. for accessing to IATS-CSIC facilities. This work has been partly funded under the EU seventh Framework Program by the ARRAINA Project N288925: Advanced Research Initiatives for Nutrition & Aquaculture.Peer Reviewe

Advances in comparative endocrinology : vol. VIII

Ponències presentades al 10th Congress of the Iberian Association of Comparative Endocrinology (AIEC), celebrat a la Universitat Jaume I, els dies 23 al 25 de setembre de 2015Les diverses comunicacions presentades al 10è Congrés de la Asociación Ibérica de Endocrinología Comparada (23-25 setembre 2016, Castelló) s'agrupen en aquest volum. Les intervencions han aportat els darrers avenços en àrees científiques com ara reproducció, metabolisme, estrés, resposta immune, creixement, mineralització i pigmentació...Las diversas comunicaciones presentadas en el 10º Congreso de la Asociación Ibérica de Endocrinología Comparada (23-25 septiembre 2016, Castellón) se agrupan en este volumen. Las intervenciones han aportado los últimos adelantos en áreas científicas como por ejemplo reproducción, metabolismo, estrés, respuesta inmune, crecimiento, mineralización y pigmentación...The present volume of Advances in Comparative Endocrinology collects the contributions of the participants at the 10th Congress of the Iberian Association of Comparative Endocrinology (AIEC). Eighteen years after the foundational meeting of our Association in Peñíscola, the return of this Congress to Castellón highlights the growing success of this initiative to foster the research and scientific development in the field of comparative endocrinology developed in the Iberian Peninsula. AIEC meetings have proven to be a way to keep in contact among research groups with common interests. Some of the participants in this last meeting were also present in the foundational one, others members came after and keep assisting every time. As one of the aims of AIEC has been to encourage students to participate, we are particulary proud of those young students and doctors from the first editions that have gained more permanent positions and continue participating in the AIEC meetings with new students

Wide-gene expression analysis of lipid-relevant genes in nutritionally challenged gilthead sea bream (Sparus aurata)

Disturbances of lipid metabolism are a major problem in livestock fish and the present study analysed the different tissue expression patterns and regulations of 40 lipid-relevant genes in gilthead sea bream. Nineteen sequences, including fatty acid elongases (4), phospholipases (7), acylglycerol lipases (8) and lipase-maturating enzymes (1), were new for gilthead sea bream (GenBank, JX975700-JX975718). Up to six different lipase-related enzymes were highly expressed in adipose tissue and liver, which also showed a high expression level of δ6 and δ9 desaturases. In the brain, the greatest gene expression level was achieved by the very long chain fatty acid elongation 1, along with relatively high levels of δ9 desaturases and the phospholipase retinoic acid receptor responder. These two enzymes were also expressed at a high level in white skeletal muscle, which also shared a high expression of lipid oxidative enzymes. An overall down-regulation trend was observed in liver and adipose tissue in response to fasting following the depletion of lipid stores. The white skeletal muscle of fasted fish showed a strong down-regulation of δ9 desaturases in conjunction with a consistent up-regulation of the >lipolytic machinery> including key enzymes of tissue fatty acid uptake and mitochondrial fatty acid transport and oxidation. In contrast, the gene expression profile of the brain remained almost unaltered in fasted fish, which highlights the different tissue plasticity of lipid-related genes. Taken together, these findings provide new fish genomic resources and contribute to define the most informative set of lipid-relevant genes for a given tissue and physiological condition in gilthead sea bream. © 2014 Elsevier B.V.This research was funded by the Spanish MICINN through AQUAFAT (AGL2009-07797; predictive modelling of flesh fatty acid composition in cultured fish species with different muscle lipid contents) and AQUAGENOMICS (CSD2007-00002, improvement of aquaculture production by the use of biotechnological tools) projects. Additional funding was obtained from EU project ARRAINA (KBBE-2011-5-288925, advanced research initiatives for nutrition and aquaculture).Peer Reviewe

Trace element accumulation in plants from an aridic area affected by mining activities

Trace element contamination has been a serious problem in the vicinity of abandoned mine sites. In the studied area, mining activities have produced great amounts of wastes, characterized by high trace elements content, acidic pH and minerals from supergene alteration. Trace elements have been dispersed, both downstream and downslope from the mine mainly due, mainly, to surface run-off. Trace elements hydric mobilization usually takes place during the rainy season, an important pollution route in the studied area. A wide range of techniques have been proposed to remediate soils polluted by trace elements. Among them, phytoremediation-based technologies could provide a long-lasting solution. The aimof thisworkwas to determine trace element concentration in roots and leaves of five plant species (Limonium carthaginens, Arthrocnemum macrostachyum, Dittrichia viscosa, Glaucium flavum and Zygophyllum fabago) growing in soils polluted by mining activities in order to determine which part of the plants accumulate heavymetals to the greatest extent. Themetal concentrations in plants varied with plant species. Plant accumulation results showed that Z. fabago could act as an accumulator for Fe, and A. macrostachyum could accumulate in Fe, As and Mn. The other plant species collected from the mining sites were tolerant to trace element contamination

Growth-promoting effects of sustained swimming in fingerlings of gilthead sea bream (Sparus aurata L.)

Fish growth is strongly influenced by environmental and nutritional factors and changing culture conditions can help optimize it. The importance of early-life experience on the muscle phenotype later in life is well known. Here, we study the effects of 5 weeks of moderate and sustained swimming activity (5 BL s) in gilthead sea bream during early development. We analysed growth and body indexes, plasma IGF-I and GH levels, feed conversion, composition [proximate and isotopic (N/C)] and metabolic key enzymes (COX, CS, LDH, HOAD, HK, ALAT, ASAT) of white muscle. Moderate and continuous exercise in fingerlings of gilthead sea bream increased plasma IGF-I, whereas it reduced plasma GH. Under these conditions, growth rate improved without any modification to feed intake through an increase in muscle mass and a reduction in mesenteric fat deposits. There were no changes in the content and turnover of muscle proteins and lipid reserves. Glycogen stores were maintained, but glycogen turnover was higher in white muscle of exercised fish. A lower LDH/CS ratio demonstrated an improvement in the aerobic capacity of white muscle, while a reduction in the COX/CS ratio possibly indicated a functional adaptation of mitochondria to adjust to the tissue-specific energy demand and metabolic fuel availability in exercised fish. We discuss the synergistic effects of dietary nutrients and sustained exercise on the different mitochondrial responses.A.M.C and E.J.V. are supported by a predoctoral fellowship from the “Ministerio de Ciencia e Innovación” (MICINN) and A.M.P. by a fellowship from the University of Barcelona (APIF-2012). This study was supported by the projects from the MICINN AGL2012-39768, and the “Xarxa de Refèrencia d’R+D+I en Aqüicultura” and the SGR2009-00402 from the “Generalitat de Catalunya”.Peer Reviewe

Diet and exercise modulate gh-igfs axis, proteolytic markers and myogenic regulatory factors in juveniles of gilthead sea bream (Sparus aurata)

© 2021 by the authors.The physiological and endocrine benefits of sustained exercise in fish were largely demonstrated, and this work examines how the swimming activity can modify the effects of two diets (high-protein, HP: 54% proteins, 15% lipids; high-energy, HE: 50% proteins, 20% lipids) on different growth performance markers in gilthead sea bream juveniles. After 6 weeks of experimentation, fish under voluntary swimming and fed with HP showed significantly higher circulating growth hormone (GH) levels and plasma GH/insulin-like growth-1 (IGF-1) ratio than fish fed with HE, but under exercise, differences disappeared. The transcriptional profile of the GH-IGFs axis molecules and myogenic regulatory factors in liver and muscle was barely affected by diet and swimming conditions. Under voluntary swimming, fish fed with HE showed significantly increased mRNA levels of capn1, capn2, capn3, capns1a, n3, and ub, decreased gene and protein expression of Ctsl and Mafbx and lower muscle texture than fish fed with HP. When fish were exposed to sustained exercise, diet-induced differences in proteases’ expression and muscle texture almost disappeared. Overall, these results suggest that exercise might be a useful tool to minimize nutrient imbalances and that proteolytic genes could be good markers of the culture conditions and dietary treatments in fish.This study was supported by the projects from the “Ministerio de Economía y Competitividad” (MINECO) AGL2015-70679-R and RTI2018-100757-B-I00 to J.G. and J.B., and the “Xarxa de Refèrencia d’R+D+I en Aqüicultura” and the 2017SGR1574 from the “Generalitat de Catalunya”. M.P.- A., I.G.-P. and E.J.V. were supported by predoctoral fellowships from the MINECO, BES-2016-078697, PRE2019-089578 and BES-2013-062949, respectively

Modulation of the IgM gene expression and IgM immunoreactive cell distribution by the nutritional background in gilthead sea bream (Sparus aurata) challenged with Enteromyxum leei (Myxozoa)

The aim of the present work was to determine if a plant protein-based diet containing vegetable oils (VO) as the major lipid source could alter the distribution of IgM immunoreactive cells (IRCs) and the IgM expression pattern in the intestine and haematopoietic tissues of gilthead sea bream (GSB) (. Sparus aurata) challenged with the myxosporean Enteromyxum leei. In a first trial (T1), GSB fed for 9 months either a fish oil (FO) diet or a blend of VO at 66% of replacement (66VO diet) was challenged by exposure to parasite-contaminated water effluent. All fish were periodically and non-lethally sampled to know their infection status. After 102 days of exposure, samples of intestine and head kidney were obtained for IgM expression and immunohistochemical detection (IHC). Additional samples of spleen were taken for IHC. Fish were categorized as control (C, not exposed), and early (E), or late (L) infected. The 66VO diet had no effect on the number of IgM-IRCs in any of the tissues or on IgM expression in C fish, whereas the infection with E. leei had a strong effect on the intestine. A combined time-diet effect was also observed, since the highest expression and IRCs values were registered in the posterior intestine (Pi) of E-66VO fish. A positive correlation was found between IgM expression and the presence of IgM-IRCs in the Pi. The effect of the time of infection was studied more in detail in a second trial (T2) in which samples of Pi were taken at 0, 24, 51, 91 and 133 days after exposure to the parasite. A significant increase of the IgM expression was detected only in parasitized fish, and very late after exposure. These results show that the duration of the exposure to the parasite is the most determinant factor for the observed intestinal IgM increased phenotype which gets magnified by the feeding of a high VO-based diet. © 2012 Elsevier Ltd.This work was funded by EU through projects AQUAMAX (FOOD-CT-2006-16249; Sustainable Aquafeeds to Maximise the Health Benefits of Farmed Fish for Consumers) and ARRAINA (Advanced Research Initiatives for Nutrition & Aquaculture, FP7/2007/2013; grant agreement n° 288925), and by the Spanish Ministry of Science and Innovation (MICINN) through the project AGL2009-13282-C02-01. Additional funding was obtained from the “Generalitat Valenciana” (research grant PROMETEO 2010/006). I. E. received a Spanish PhD fellowship (FPI) from MICINN.Peer Reviewe

Up-scaling validation of a dummy regression approach for predictive modelling the fillet fatty acid composition of cultured European sea bass (Dicentrarchus labrax)

The aim of the study was to validate a dummy regression approach for predictive modelling the fillet fatty acid (FA) composition of cultured European sea bass with dietary FA composition and lipid fillet content as independent variables. The model used our own data on gilthead sea bream as reference subgroup dataset and data from turbot, sole and European sea bass as dummy variables. Most of the observed variance within and among species was explained by the regression model without statistical significant interactions on blocks between diet composition and fish species subgroups. For the validation of European sea bass FA descriptors, predictive values derived from data on fish reared at laboratory scale were plotted against those obtained in farmed fish harvested at commercial size. A close linear association near to equality was found for 12 representative FAs, including saturated FAs, monoenenes and polyunsaturated FAs. This finding reinforces the possibility to produce tailored and healthy seafood products according to the guidelines of essential FA requirements in humans. FA algorithms for all the species in the model are hosted at www.nutrigroup-iats.org/aquafat as a multispecies tool to interrogate the nutritionally regulated FA composition of four cultured marine fish species of a high added value.This study was founded by Spanish (AQUAFAT, AGL2009-07797, Predictive modelling of flesh fatty acid composition in cultured fish species with different muscle lipid content) and EU (ARRAINA, KBBE-2011-5-288925, Advanced research initiatives for nutrition and aquaculture) projects. Additional founding was obtained from the “Generalitat Valenciana” (research grant PROMETEO 2010/006). GFB-L was recipient of a Spanish PhD fellowship from the Diputación Provincial de Castellón.Peer Reviewe

Multi-class determination of undesirables in aquaculture samples by gas chromatography/tandem mass spectrometry with atmospheric pressure chemical ionization: A novel approach for polycyclic aromatic hydrocarbons

In this work, a method for the analysis of 24 PAHs in 19 different matrices, including fish tissues, feeds and feed ingredients, has been developed using gas chromatography coupled to triple quadrupole tandem mass spectrometry with atmospheric pressure chemical ionization source (GC-APCI-MS/MS). The method is based on a modification of the unbuffered QuEChERS method, using freezing as an additional clean-up step and applying a 20-fold dilution factor to the final extract. The procedure was also tested for 15 pesticides and 7 polychlorinated biphenyl (PCB) congeners in order to widen the scope of the method. The excellent sensitivity and selectivity provided by GC-APCI-MS/MS allowed the dilution of the sample extracts and quantification using calibration with standards in solvent for all the 19 matrices tested. The developed method was evaluated at 2, 5 and 50 ng·g-1 spiking levels. LOQs were 2 ng·g-1 for most compounds, and LODs ranged from 0.5 to 2 ng·g-1. Analysis of real-world samples revealed the presence of naphthalene, fluorene, phenanthrene, fluoranthene and pyrene at concentration levels ranging from 4.8 to 187 ng·g-1. No PCBs, DDTs and pesticides were found in fillets from salmon and sea bream