Advanced Research Initiatives for Nutrition & Aquaculture

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Early nutritional programming in fish: tailoring the metabolic use of dietary carbohydrates

Publication . Rocha, Filipa; Dinis, Maria Teresa; Dias, Jorge; Panresat, Stéphane

Sustainable feeding practices in aquaculture require a higher use of vegetable feedstuffs, which are naturally rich in carbohydrates. This can raise some constrains to fish species with carnivorous feeding habits, due to their poor ability to use dietary carbohydrates. This thesis aimed to explore the potential of nutritional programming as a new strategy to better understand the mechanisms underlying the impaired utilization of dietary carbohydrates in fish. The experimental work relied on multiple approaches: a) rearing trials with larvae and juvenile fish for assessment of zootechnical criteria; b) analysis with radiolabeled tracers to follow the metabolic flux of nutrients; c) and genomic expression of key metabolic-genes. In Chapters 2 and 3, we evaluated how the supplementation of egg-yolk with glucose, through microinjection, could act as a stimulus and permanently alter some metabolic pathways in zebrafish. Microinjection was proven an efficient technique to alter the nutritional composition of embryo’s yolk. We saw that the embryonic window for stimulus delivery is crucial in determining future outcomes. The late embryo stage was found more suitable to exert a glucidic stimulus compared with incipient stages of embryogenesis, based on molecular and metabolic analyses that suggested an improved capacity for glucose utilization. Chapters 4 and 5 aimed the nutritional programming of the carbohydrate-related metabolic pathways in gilthead seabream. Recurrent hyperglucidic stimuli were delivered at early larval development using live preys and a glucose-rich diet, demonstrating that nutritional stimuli can be performed in a marine fish species during sensitive stages of development, without compromising survival and growth. We found some short-term effects after stimulus delivery, on gene expression pattern and metabolic utilization of glucose of post-larvae. In contrast, juvenile fish exposed to the early stimuli showed only few changes on glucose utilization, namely a higher absorption of dietary starch. This thesis has generated new knowledge on the triggering effect of early glucidic events upon the regulation of key metabolic processes, contributing to a better comprehension over the concept of nutritional programming in fish.

2015-11-30Doctoral thesis

Open access

High-glucose feeding of gilthead seabream (Sparus aurata) larvae: effects on molecular and metabolic pathways

Publication . Rocha, Filipa; Dias, Jorge; Geurden, Inge; Dinis, Maria Teresa; Panserat, Stephane; Engrola, S.

Nutritional programming has begun to arouse interest as a novel tool to alter specific metabolic pathways or functions in farmed animals. The aim of the present study was to explore the potential of early glucose stimuli to induce changes in nutrient metabolism of gilthead seabream. Nutritional conditioning was performed by delivering glucose-rich feed at three distinct recurrent periods of larval feeding regime: during first-feeding with rotifers (3 days after hatching, DAH) and mid-feeding with Artemia metanauplii (20DAH) and the beginning of inert diet feeding (30DAH), called the Recurrent treatment (REC). As opposed, the control treatment (CTRL) did not experience any glucose stimuli. At post-larval stage (from 50 to 60DAH), both treatments were challenged with a high-carbohydrate diet (50%). The immediate response to the early stimuli was assessed through gene expression of metabolic markers and by nutrient metabolism using [C-14] tracers. Each dietary stimulus induced metabolic changes on REC larvae, shown by altered expression of some genes, including those involved in glycolysis, and by a different pattern of glucose utilization. However, none of the molecular adaptations (except G6PDH gene) were persistent in the viscera and muscle of challenged post-larvae from REC group. In contrast, the glucose metabolism of challenged REC post-larvae revealed a shift towards a higher catabolism and lower glucose retention in tissues, compared to the CTRL group, suggesting an improvement of glucose oxidation pathways. In addition, the REC group showed a higher bio-conversion of glucose into lipids, indicating enhanced hepatic lipogenesis. The early stimuli did not affect the relative retention or use of amino acids or the growth and survival of challenged fish, up to 60DAH. In summary, although not substantiated at a molecular level, our data reveal that a recurrent high-glucose stimulus during larval stages affects the short-term modulation of pathways for glucose utilization in gilthead seabream. (C) 2015 Elsevier B.V. All rights reserved.

2016-01Journal article

Restricted access

Dietary butyrate helps to restore the Intestinal status of a marine teleost (Sparus aurata) fed extreme diets low in fish meal and fish oil

Publication . Estensoro, Itziar; Ballester-Lozano, Gabriel; Benedito-Palos, Laura; Grammes, Fabian; Martos-Sitcha, Juan Antonio; Mydland, Liv-Torunn; Calduch-Giner, Josep Alvar; Fuentes, Juan; Karalazos, Vasileios; Ortiz, Alvaro; Overland, Margareth; Sitja-Bobadilla, Ariadna; Perez-Sanchez, Jaume

There is a constant need to find feed additives that improve health and nutrition of farmed fish and lessen the intestinal inflammation induced by plant-based ingredients. The objective of this study was to evaluate the effects of adding an organic acid salt to alleviate some of the detrimental effects of extreme plant-ingredient substitution of fish meal (FM) and fish oil (FO) in gilthead sea bream diet. Three experiments were conducted. In a first trial (T1), the best dose (0.4%) of sodium butyrate (BP-70 (R) NOREL) was chosen after a short (9 weeks) feeding period. In a second longer trial (T2) (8 months), four diets were used: a control diet containing 25% FM (T2-D1) and three experimental diets containing 5% FM (T2-D2, T2-D3, T2-D4). FO was the only added oil in D1, while a blend of plant oils replaced 58% and 84% of FO in T2-D2, and T2-D3 and T2-D4, respectively. The latter was supplemented with 0.4% BP-70. In a third trial (T3), two groups of fish were fed for 12 and 38 months with D1, D3 and D4 diets of T2. The effects of dietary changes were studied using histochemical, immunohistochemical, molecular and electrophysiological tools. The extreme diet (T2-D3) modified significantly the transcriptomic profile, especially at the anterior intestine, up-regulating the expression of inflammatory markers, in coincidence with a higher presence of granulocytes and lymphocytes in the submucosa, and changing genes involved in antioxidant defences, epithelial permeability and mucus production. Trans-epithelial electrical resistance (Rt) was also decreased (T3-D3). Most of these modifications were returned to control values with the addition of BP-70. None of the experimental diets modified the staining pattern of PCNA, FABP2 or ALPI. These results further confirm the potential of this additive to improve or reverse the detrimental effects of extreme fish diet formulations.

2016-11Journal article

Open access

Parental and early-feeding effects of dietary methionine in rainbow trout (Oncorhynchus mykiss)

Publication . Fontagne-Dicharry, Stephanie; Alami-Durante, Helene; Aragão, Cláudia; Kaushik, Sadasivam J.; Geurden, Inge

We studied the effect of changes in dietary methionine (Met) supply in broodstock and first-feeding rainbow trout fry (offspring). Three plant-based diets differing in Met level (deficient, adequate or in excess of the established requirement) were fed to the broodstock (male and female) for 6 months prior to spawning (diets BD, BA and BE, respectively). The offspring from the parental Met-groups was then challenged in turn with the different Met fry-diets (FD, FA and FE, respectively) for 3 weeks from first-feeding. At spawning, females fed diet BD had significantly higher plasma total and LDL-cholesterol and slightly lower plasma triacylglycerol. Diet BD reduced female (but not male) growth, weight of spawn and egg size, but had no effect on relative fecundity. The free amino acid profile of oocytes was modified, with levels of Met and Cys correlating positively with the Met-levels of broodstock diets. SAM and SAH levels in oocytes followed the same pattern, as opposed to SAM/SAH ratio. At the swim-up stage, no significant effect of parental diet on fry weight was noted, whereas survival was the highest in fry from BE-broodstock. The subsequent 21-day fry feeding with different Met levels highly affected the daily growth index with a significant interaction between the parental-diet and fry-diet effects. The expression of a number of genes regulating sulfur amino acid metabolism was modified either directly by the dietary Met supply in both broodstock liver and in whole fry (e.g. BHMT1, GR, GST pi, MsrA1) or indirectly by the parental Met intakes as seen in the swim-up fry (e.g. BHMT1, MTR, GST pi, MsrA1). Importantly, long-lasting parental effects linked to broodstock Met-intake were seen in the fry, 21-days after first-feeding and irrespective of the fry diet (CTH, MsrA1, MsrB2, SOD2). Similarly, parental effects were noted on the gene expression of both NPY and POMC feeding peptides in fry prior to exogenous feeding which persisted for POMC in the 21-day fry. Parental effects were also demonstrated on the key myogenic gene Myog, on fMHC and GDH in swim-up fry, which persisted for GDH in 21-day fry. In summary, our results demonstrate that dietary Met levels of rainbow trout broodstock affect various traits in the offspring, some of which persisted during the first weeks of exogenous feeding. Further studies need to evaluate the long-term persistence of the parental effects over time and to elucidate the mechanisms, whether epigenetic or not. Statement of relevance: Determining the multiple effects of dietary methionine levels on reproductive, growth performance and metabolism in offspring will help improve formulations of low fish meal feeds for rainbow trout at sensitive life cycle stages. (C) 2016 Elsevier B.V. All rights reserved.

2017-02Journal article

Open access