Browsing by Author "Martos-Sitcha, Juan A."
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- Dietary tryptophan supplementation induces a transient immune enhancement of gilthead seabream (Sparus aurata) juveniles fed fishmeal-free dietsPublication . Ramos-Pinto, Lourenco; Martos-Sitcha, Juan A.; Reis, Bruno; Azeredo, Rita; Fernandez-Boo, Sergio; Perez-Sanchez, Jaume; Alvar Calduch-Giner, Josep; Engrola, Sofia; Conceicao, Luis E. C.; Dias, Jorge; Silva, Tome S.; Costas, BenjaminEuropean aquaculture is an industry with a high sustainability profile contributing to the supply of safe seafood. However, several diseases can affect farmed fish and it is imperative to find alternatives for chemotherapeutic treatments when disease outbreaks occur. Maintenance of health through nutrition is well-establish in modern animal farming, and amino acids (AA) are promising candidates as functional additives to improve fish health. Therefore, the goal of this research is to provide a better understanding of the influence of tryptophan supplementation on nutritional condition and immune mechanisms in fish. Triplicate groups of fish (13.3 +/- 0.3g) previously fed with a fishmeal-based diet were either fed a control diet with an extreme formulation (0% fishmeal) but meeting the AA requirements (CTRL), or the SUP diet, formulated as the CTRL with an increase in tryptophan (TRP) content. After 2 and 13 weeks of feeding, head-kidney (HK), liver (L) and white skeletal muscle (WSM) were collected for gene expression, whereas plasma was suited for humoral immune parameters. A holistic approach using transcriptomic, humoral and zootechnical parameters was undertaken. The expression of 29-31 genes for WSM, L or HK confirms an effect due to the treatment across time. A two-way ANOVA analysis revealed that 15-24 genes varied significantly depending on the tissue, and the multivariate analysis by means of PLS-DA explained (R-2) and predicted (Q(2)) with four components up to 93% and 78% of total variance, respectively. Component 1 (R-2 = 50.06%) represented the time effects, whereas components 2 (24.36%) and 3 (13.89%) grouped fish on the basis of dietary treatment, at early sampling. The HK results in particular suggest that fish fed SUP diet displayed an immunostimulated state at 2 weeks. No major differences were observed in plasma humoral parameters, despite an increase in antiprotease and peroxidase activities after 13 weeks regardless of dietary treatment. These results suggest that tryptophan supplementation may improve the seabream immune status after 2 weeks. Hence, the use of functional feeds is especially relevant during a short-term feeding period before a predictable stressful event or disease outbreak, considering that these putative advantageous effects seem to disappear after a 13 weeks feeding period.
- High plant protein diet impairs growth performance and intestinal integrity in greater amberjack (Seriola dumerili): Molecular and physiological insightsPublication . Fuentes, Juan; Fonseca, Filomena; Gregorio, Silvia; Kussaba Miguel, Larissa; Perera, Erick; Alarcón-López, Francisco J.; Martos-Sitcha, Juan A.The Mediterranean aquaculture industry that produces mainly seabream and seabass is exploring alternative plant-based protein sources for fish feeds together with the diversification of fish species. Effective plant-based formulations require diverse sources and additives to maintain fish welfare and growth, which is especially important for carnivorous species. In this scenario, the objective of the present study was to evaluate the impact of a high percentage of fishmeal replacement with protein of plant origin in Seriola dumerili, a fast-growing species with a high protein requirement. Two diets were developed: MAP (marine animal protein) with a protein content of 92 % of animal origin and PPB (plant protein blend) with a 50 % replacement of protein of animal origin with plant protein. We combined electrophysiology measurements with expression analysis of claudins and members of the SLC superfamily of solute carriers to unravel and characterise putative markers of intestinal integrity and absorption. The replacement resulted in shorter and lighter fish with a reduction in growth rate (SGR) from 2.6 to 2. We simultaneously observed lower transepithelial tissue resistance (TER), lower permeability, and decreased cld12 expression in the anterior intestine. In addition, we demonstrated a strong regiondependent electrogenic transport of essential amino acids, with the mid-intestine having the highest transport capacity. The comparative study performed in the mid-intestine with fish fed the MAP or the PPB diets exposed a negative effect of dietary replacement with plant protein. No significant dietary impact on di- and tri-peptide transporters (SLC15) was found at the molecular level. However, a clear region-dependent expression pattern of slc15a1, slc15a2, and slc15a4 was observed, which warrants further investigation. The expression pattern of slc7a5 showed the effect of the diet, but in contrast, the diet and intestinal region affected the expression of its functionally associated slc3a1 and slc3a2 for amino acid antiport, with the strongest effects in the posterior intestine. The integrity and absorption impairments detected in response to protein source replacement will likely underlie the significant growth differences observed between the two dietary regimes.