Percorrer por autor "Santos, Paulo"
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- Development and testing of a dual accelerometer vector sensor for AUV acoustic surveysPublication . Mantouka, Agni; Felisberto, Paulo; Santos, Paulo; Zabel, Friedrich; Saleiro, Mário; Jesus, Sergio M.; Sebastiao, LuisThis paper presents the design, manufacturing and testing of a Dual Accelerometer Vector Sensor (DAVS). The device was built within the activities of theWiMUST project, supported under the Horizon 2020 Framework Programme, which aims to improve the efficiency of the methodologies used to perform geophysical acoustic surveys at sea by the use of Autonomous Underwater Vehicles (AUVs). The DAVS has the potential to contribute to this aim in various ways, for example, owing to its spatial filtering capability, it may reduce the amount of post processing by discriminating the bottom from the surface reflections. Additionally, its compact size allows easier integration with AUVs and hence facilitates the vehicle manoeuvrability compared to the classical towed arrays. The present paper is focused on results related to acoustic wave azimuth estimation as an example of its spatial filtering capabilities. The DAVS device consists of two tri-axial accelerometers and one hydrophone moulded in one unit. Sensitivity and directionality of these three sensors were measured in a tank, whilst the direction estimation capabilities of the accelerometers paired with the hydrophone, forming a vector sensor, were evaluated on a Medusa Class AUV, which was sailing around a deployed sound source. Results of these measurements are presented in this paper.
- Immune status and hepatic antioxidant capacity of Gilthead Seabream Sparus aurata juveniles fed yeast and microalga derived β-glucansPublication . Reis, Bruno; Gonçalves, Ana Teresa; Santos, Paulo; Sardinha, Manuel; Conceição, Luís E. C.; Serradeiro, Renata; Pérez-Sánchez, Jaume; Calduch-Giner, Josep; Schmid-Staiger, Ulrike; Frick, Konstantin; Dias, Jorge; Costas, BenjamínThis work aimed to evaluate the effects of dietary supplementation with β-glucans extracted from yeast (Saccharomyces cerevisiae) and microalga (Phaeodactylum tricornutum) on gene expression, oxidative stress biomarkers and plasma immune parameters in gilthead seabream (Sparus aurata) juveniles. A practical commercial diet was used as the control (CTRL), and three others based on CTRL were further supplemented with different β-glucan extracts. One was derived from S. cerevisiae (diet MG) and two different extracts of 21% and 37% P. tricornutum-derived β-glucans (defined as Phaeo21 and Phaeo37), to give a final 0.06% β-glucan dietary concentration. Quadruplicate groups of 95 gilthead seabream (initial body weight: 4.1 ± 0.1 g) were fed to satiation three times a day for 8 weeks in a pulse-feeding regimen, with experimental diets intercalated with the CTRL dietary treatment every 2 weeks. After 8 weeks of feeding, all groups showed equal growth performance and no changes were found in plasma innate immune status. Nonetheless, fish groups fed β-glucans supplemented diets showed an improved anti-oxidant status compared to those fed CTRL at both sampling points (i.e., 2 and 8 weeks). The intestinal gene expression analysis highlighted the immunomodulatory role of Phaeo37 diet after 8 weeks, inducing an immune tolerance effect in gilthead seabream intestine, and a general down-regulation of immune-related gene expression. In conclusion, the results suggest that the dietary pulse administration of a P. tricornutum 37% enriched-β-glucans extract might be used as a counter-measure in a context of gut inflammation, due to its immune-tolerant and anti-oxidative effects.
- Immunomodulatory effects of dietary methionine supplementation in rainbow trout (Oncorhynchus mykiss) juveniles: insights following vaccination and infection response against Yersinia ruckeriPublication . Carvalho, Inês; Schoninger, Felipe Bolgenhagen; Pereira da Cunha, André; Peixoto, Diogo; Brito, Francisca; Simões, Luara; Vaz, Mariana; Stensballe, Allan; Ferreira, Inês; Santos, Paulo; Tafalla, Carolina; Machado, Marina; Costas, BenjamínMethionine, an essential amino acid, participates in various pathways with implications for the immune system. Recent evidence suggests that it may support both innate and adaptive immune mechanisms. In the present study, it was hypothesized that dietary methionine supplementation prior to vaccination may be a promising strategy to improve vaccine efficacy. Hence, the current research aimed to evaluate the effects of dietary methionine supplementation on the immune status of rainbow trout (Oncorhynchus mykiss) juveniles, its role in modulating immune responses, as well as its potential synergistic effects with a commercial vaccine. To this end, fish were fed either a control diet (CTRL), meeting the methionine requirements of the species, or a methioninesupplemented diet (MET). After 4 weeks, half of the fish within each dietary group were either dip-vaccinated against Yersinia ruckeri (vaccinated) or left unvaccinated (naïve). Twenty-one days post-vaccination, during which fish continued on their respective dietary treatment, fish were intraperitoneally challenged with Y. ruckeri or injected with HBSS to serve as a control. Bacterial load in gills, posterior gut and spleen tissues, hematological parameters, differential cell counts, hepatic metabolites and antioxidant defenses, gene expression in the head-kidney and liver tissues, and plasma proteomic profiles were assessed following feeding trial and immunization period, and at early time points post-infection. Mortality was also monitored. Naïve fish exhibited a higher prevalence of Y. ruckeri, along with increased expression of pro-inflammatory and innate immune genes compared to their vaccinated counterparts. In contrast, vaccinated fish appeared to resolve the infection more rapidly, possibly through an early and heightened production of reactive oxygen species. In naïve fish, methionine supplementation appeared to impair antioxidant defenses and prolong immune activation, potentially contributing to the higher bacterial burden and reduced survival observed in this group. Differences between the two vaccinated groups were subtle, with no mortality recorded in either. However, proteomic analyses at 24 h post-infection revealed distinct responses, with MET-fed vaccinated fish exhibiting an increase in hemostasisrelated proteins, while CTRL-fed vaccinated fish showed a response more akin to pre-infection groups. Methionine supplementation in combination with vaccination appeared to promote slightly faster pathogen clearance.
- Tryptophan modulatory role in European Seabass (Dicentrarchus labrax) immune response to acute inflammation under stressful conditionsPublication . Machado, Marina; Peixoto, Diogo; Santos, Paulo; Ricardo, Ana; Duarte, Inês; Carvalho, Inês; Raquel Cêa de Aragão Teixeira, Cláudia; Azeredo, Rita; Costas, BenjamínThe present work aimed to study the role of dietary tryptophan supplementation in modulating the European seabass (Dicentrarchus labrax) immune condition during stressful rearing conditions (i.e., 15 days exposure to high density), as well as the immune response to acute inflammation after intraperitoneal injection of a bacterial pathogen. Stress alone did not compromise seabass health indicators. In contrast, a clear peripheral and local inflammatory response was observed in response to the inoculated bacteria. Moreover, exposure to a high stocking density seemed to exacerbate the inflammatory response at early sampling points, compared to fish stocked at a lower density. In contrast, stressed fish presented some immune-suppressing effects on the T-cell surface glycoprotein receptor expressions at a late sampling point following inflammation. Regarding the effects of dietary tryptophan, no changes were observed on seabass immune indicators prior to inflammation, while a small number of immunosuppressive effects were observed in response to inflammation, supporting tryptophan’s role in the promotion of immune-tolerance signals during inflammation. Nonetheless, tryptophan dietary supplementation improved the inflammatory response against a bacterial pathogen during stressful conditions, supported by a reduction of plasma cortisol levels, an up-regulation of several immune-related genes at 48 h, and an inversion of the previously observed, stress-induced T-cell suppression. Finally, the involvement of tryptophan catabolism in macrophages was confirmed by the up-regulation of genes involved in the kynurenine pathway. The present study brings new insights regarding the immune modulatory role of tryptophan during stressful conditions in fish, thus allowing for the development of novel prophylactic protocols during vaccination by intraperitoneal injection in the European seabass.