Browsing by Author "Dias, J."
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- Avanços recentes em nutrição de larvas de peixesPublication . Conceicao, Luis; Aragão, C.; Richard, Nadège; Engrola, S.; Gavaia, Paulo; Mira, Sara; Dias, J.Os requisitos nutricionais de larvas de peixes são ainda mal compreendidos, o que leva a altas mortalidades e problemas de qualidade no seu cultivo. Este trabalho pretende fazer uma revisão de novas metodologias de investigação, tais como estudos com marcadores, genómica populacional, programação nutricional, génomica e proteómica funcionais, e fornecer ainda alguns exemplos das utilizações presentes e perspectivas futuras em estudos de nutrição de larvas de peixes.
- Dietary lipid quality regulates bone composition and metabolism in gilthead seabream (Sparus aurata) juvenilesPublication . Dias, J.; Rodrigues, V.; Colen, Rita; Rosa, Joana; Viegas, Michael; Cardeira Da Silva, João; Cancela, Leonor; Gavaia, Paulo J.; Laizé, VincentReplacement of significant amounts of marine fish oils by vegetable oils is a major trend in the aquaculture feed industry. However, knowledge on the mechanisms underlying the nutritional regulation of bone metabolism is extremely scarce in fish. We speculate that changes in the dietary ratio of fatty acids may modulate tissue eicosanoids production and affect bone formation in fastgrowing gilthead seabream, an important fish species for aquaculture in the Mediterranean region.
- Dietary nitrogen and fish welfarePublication . Conceição, L. E. C.; Aragão, C.; Dias, J.; Costas, B.; Terova, G.; Martins, C.; Tort, L.Little research has been done in optimizing the nitrogenous fraction of the fish diets in order to minimize welfare problems. The purpose of this review is to give an overview on how amino acid (AA) metabolism may be affected when fish are under stress and the possible effects on fish welfare when sub-optimal dietary nitrogen formulations are used to feed fish. In addition, it intends to evaluate the current possibilities, and future prospects, of using improved dietary nitrogen formulations to help fish coping with predictable stressful periods. Both metabolomic and genomic evidence show that stressful husbandry conditions affect AA metabolism in fish and may bring an increase in the requirement of indispensable AA. Supplementation in arginine and leucine, but also eventually in lysine, methionine, threonine and glutamine, may have an important role in enhancing the innate immune system. Tryptophan, as precursor for serotonin, modulates aggressive behaviour and feed intake in fish. Bioactive peptides may bring important advances in immunocompetence, disease control and other aspects of welfare of cultured fish. Fishmeal replacement may reduce immune competence, and the full nutritional potential of plant-protein ingredients is attained only after the removal or inactivation of some antinutritional factors. This review shows that AA metabolism is affected when fish are under stress, and this together with sub-optimal dietary nitrogen formulations may affect fish welfare. Furthermore, improved dietary nitrogen formulations may help fish coping with predictable stressful events.
- Dietary tools to modulate glycogen storage in gilthead seabream muscle: glycerol supplementationPublication . Silva, Tomé S.; Matos, Elisabete; Cordeiro, O.; Colen, Rita; Wulff, Tune; Sampaio, Eduardo; Sousa, Vera; Valente, L. M. P.; Gonçalves, Amparo; Silva, Joana M. G.; Bandarra, N.; Nunes, Maria Leonor; Dinis, Maria Teresa; Dias, J.; Jessen, Flemming; Rodrigues, PedroThe quality and shelf life of fish meat products depend on the skeletal muscle’s energetic state at slaughter, as meat decomposition processes can be exacerbated by energy depletion. In this study, we tested dietary glycerol as a way of replenishing muscle glycogen reserves of farmed gilthead seabream. Two diets were tested in duplicate (n = 42/tank). Results show 5% inclusion of crude glycerol in gilthead seabream diets induces increased muscle glycogen, ATP levels and firmness, with no deleterious effects in terms of growth, proximate composition, fatty acid profile, oxidative state, and organoleptic properties (aroma and color). Proteomic analysis showed a low impact of glycerol-supplementation on muscle metabolism, with most changes probably reflecting increased stress coping capacity in glycerol-fed fish. This suggests inclusion of crude glycerol in gilthead seabream diets (particularly in the finishing phase) seems like a viable strategy to increase glycogen deposition in muscle without negatively impacting fish welfare and quality.
- Effect of harvesting stress and storage conditions on protein degradation in fillets of farmed gilthead seabream (Sparus aurata): a differential scanning calorimetry studyPublication . Matos, Elisabete; Silva, Tomé S.; Tiago, Teresa; Aureliano, M.; Dinis, Maria Teresa; Dias, J.A trial was undertaken to evaluate Differential Scanning Calorimetry (DSC) as a fast analytical tool to differentiate gilthead seabream subjected to variable conditions of slaughter stress and post-mortem storage. Fish were subjected to different harvesting stress conditions: profound anaesthesia (PA, low stress) and net crowding (NC, high stress). Fish were slaughtered in an ice-salt water slurry, and subsequently stored on ice (7 days). Additional NC fish were frozen ( 20 C) and subjected to a freeze–thaw cycle. Dorsal muscle was assessed for cathepsins activity, liquid loss and DSC analysis. It is demonstrated that DSC analysis is capable of differentiating fresh, frozen and thawed-re-frozen fish, while liquid loss and cathepsin B activity are good markers to distinguish fresh from frozen fish. Harvesting stress had little effect on myosin and actin enthalpy transitions, as observed by DSC at 49 and 74 C, respectively, but a lower DH actin/myosin ratio was found in PA fish, suggesting that intense exercise prior to slaughter promoted partial denaturation of muscle myosin.
- Effect of variable levels of dietary cholesterol and plant sterols on the growth performance and bone metabolism in gilthead seabream (Sparus aurata) juvenilesPublication . Dias, J.; Colen, Rita; Rodrigues, V.; Aragão, C.; Engrola, S.; Viegas, Michael; Laizé, Vincent; Gavaia, Paulo J.; Cancela, LeonorCholesterol is found in all animal tissues and is an important component of biological cell membranes with functions such as precursor to bile acids, hormones and vitamins. Fish meal and fish oil are cholesterol-rich ingredients. Replacement of these marine-derived ingredients by plant proteins and vegetable oils tends to reduce dietary cholesterol levels.
- Effects of dietary amino acids and repeated handling on stress response and brain monoaminergic neurotransmitters in Senegalese sole (Solea senegalensis) juvenilesPublication . Costas, B.; Aragão, C.; Soengas, J. L.; Míguez, J. M.; Rema, P.; Dias, J.; Afonso, A.; Conceição, L. E. C.The present study aimed to assess the effects of increased availability of dietary amino acids (AA) on brain monoamine neurotransmitters and the metabolic processes resulting from stressful situations in fish. Senegalese sole (Solea senegalensis) juveniles (24.2 ± 0.4 g wet mass) were weekly subjected to an acute handling stressor (HDLG) or remained undisturbed (CTL). Additionally, both treatments were fed a control or a high protein (HP) diet (CTL, CTL HP, HDLG and HDLG HP). The HP diet slightly increased the levels of digestible indispensable AA, together with tyrosine and cysteine. Repeated handling induced a stress response after 14 and 28 days in fish held at both HDLG and HDLG HP treatments. While dietary treatment and handling stress activated the serotonergic system at 14 days, these effects were not observed after 28 days. In addition, the HP diet minimized the decrease in plasma indispensable AA due to repeated handling stress after 28 days. It was concluded that HP diet decreased post-stress plasma glucose and lactate levels in HDLG HP specimens only at 14 days of treatment. Moreover, dietary treatment was also effective in stimulating DA synthesis and release, thus dietary phenylalanine supplementation can increase DA biosynthesis in fish.
- Effects of preslaughter stress levels on the post-mortem sarcoplasmic proteomic profile of gilthead seabream musclePublication . Silva, Tomé S.; Cordeiro, O.; Matos, Elisabete; Wulff, Tune; Dias, J.; Jessen, Flemming; Rodrigues, PedroFish welfare is an important concern in aquaculture, not only due to the ethical implications but also for productivity and quality-related reasons. The purpose of this study was to track soluble proteome expression in post-mortem gilthead seabream muscle and to obsere how preslaughter stress affects these post-mortem processes. For the experiment, two groups of gilthead seabream (n = 5) were subjected to distinct levels of preslaughter stress, with three muscle samples being taken from each fish. Proteins were extracted from the muscle samples, fractionated, and separated by 2DE. Protein identification was performed by MALDI-TOF-TOF MS. Analysis of the results indicates changes on several cellular pathways, with some of these changes being attributable to oxidative and proteolytic activity on sarcoplasmic proteins, together with leaking of myofibrillar proteins. These processes appear to have been hastened by preslaughter stress, confirming that it induces clear postmortem changes in the muscle proteome of gilthead seabream.
- Glucose overload in yolk has little effect on the long-term modulation of carbohydrate metabolic genes in zebrafish (Danio rerio)Publication . Rocha, Filipa; Dias, J.; Engrola, S.; Gavaia, Paulo J.; Geurden, Inge; Dinis, Maria Teresa; Panserat, S.The use of early nutritional stimuli to program metabolic pathways in fish is ill defined. Therefore, studies were undertaken with zebrafish to assess the effect of high glucose levels during the embryonic stage as a lifelong modulator of genes involved in carbohydrate metabolism. Genes related to carbohydrate metabolism were expressed at low levels at 0.2 and 1 day post-fertilization (dpf). However, from 4 dpf onwards there was a significant increase on expression of all genes, suggesting that all analysed pathways were active. By microinjection, we successfully enriched zebrafish egg yolk with glucose (a 43-fold increase of basal levels). Acute effects of glucose injection on gene expression were assessed in larvae up to 10 dpf, and the programming concept was evaluated in juveniles (41 dpf) challenged with a hyperglucidic diet. At 4 dpf, larvae from glucose-enriched eggs showed a downregulation of several genes related to glycolysis, glycogenolysis, lipogenesis and carbohydrate digestion in comparison with control (saline-injected) embryos. This inhibitory regulation was suppressed after 10 dpf. At the juvenile stage, and upon switching from a low to a high digestible carbohydrate diet, early glucose enrichment had no significant effect on most analysed genes. However, these same fish showed altered expression of the genes for cytosolic phosphoenolpyruvate carboxykinase, sodium-dependent glucose cotransporter 1 and glycogen synthase, suggesting changes to the glucose storage capacity in muscle and glucose production and transport in viscera. Overall, supplementation of egg yolk with high glucose levels had little effect on the long-term modulation of carbohydrate metabolic genes in zebrafish.
- Health status in gilthead seabream (Sparus aurata) juveniles fed diets devoid of fishmeal and supplemented with Phaeodactylum tricornutumPublication . Reis, B.; Ramos-Pinto, L.; Martos-Sitcha, J. A.; Machado, M.; Azeredo, R.; Fernandez-Boo, S.; Engrola, S.; Unamunzaga, C.; Calduch-Giner, J.; Conceicao, L. E. C.; Silva, T.; Dias, J.; Costas, B.; Perez-Sanchez, J.To enhance fish general health, feeds can be supplemented with health-promoting additives, reducing the need to use chemotherapeutics. Incorporation of marine algae biomasses in aquafeeds has been shown to improve fish immune status by enhancing innate immune response. This study evaluated the effects of Phaeodactylum tricornutum incorporation in feed by two different processes, either as freeze-dried biomass or broken cell wall biomass, on fish health status and performance. Triplicate groups of gilthead seabream juveniles (13.3 +/- 0.3 g) were either fed a control diet (CTRL) with an extreme (i.e., 0% fishmeal), nutritionally balanced, formulation, or two experimental diets formulated as the CTRL with 1% inclusion of the microalga P. tricornutum at the expense of wheat meal: BC diet contains P. tricornutum broken cells and WC diet microalgae whole cells. After 2 and 12 weeks of feeding, blood was collected for hematological procedures, whereas plasma and mucus were sampled for immune parameters. Head-kidney, liver, and white skeletal muscle were also collected for gene expression measurements. No major differences were observed in hematological nor plasma humoral parameters after 12 weeks irrespective of dietary treatment. Arrays of 29-31 genes were analyzed in the different tissues, revealing an early dietary effect (2 weeks) in a tissue-specific pattern. In the liver, the major effect was found in the GH/IGF axis and in muscle there was a late downregulation of myostatin (mstn) gene, mainly due to WC diet, even though all fish had similar growth performance. Regarding the head-kidney, BC diet led to alpha-2-macroglobulin (a2m) gene upregulation. Also, the same treatment showed increased mucus alternative complement pathway and bactericidal activity at 2 and 12 weeks, respectively. Hence, it seems that BC diet has a potential stimulatory effect that might be relevant as a prophylactic measure before a predictable stressful event.
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