Browsing by Issue Date, starting with "2024-06-25"
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- Effect of bile salts on intestinal epithelial function in gilthead seabream (Sparus aurata)Publication . Fuentes, J.; Gregorio, Silvia; F. Fonseca; Robles-Arozarena, R.; Martos-Sitcha, J. A.; Moyano, F. J.In the context of modern aquaculture, the effort to reduce the reliance on fishmeal/marine ingredients in fish diets has led to the exploration of plant-based protein sources as potential substitutes, a dietary shift that disrupts the bile acid profile in fish. Therefore, bile salts are being sought as additives. However, artificially increased intestinal levels of bile acids may significantly impact mucosal function. Therefore, here, we explored the regulatory role in the intestine of gilthead sea bream (Sparus aurata) of (i) chenodeoxycholic acid (CDC), (ii) a mixture formed by two bile acids, 3% cholic acid and 97% deoxycholic acid (MIX), and (iii) a conjugated bile salt sodium taurocholate (TC) in Ussing chambers with the epithelial voltage clamp technique. We tested the bile salts in a 50-500 mu g/ml concentration range, and all of them promoted ion absorption. Yet, clear concentration-dependent and more pronounced effects on the ion transport were observed in the posterior intestine. On the other hand, bile salts had no or minor effects on tissue resistance. However, there are indications that the MIX could have adverse effects at high concentrations (500 mu g/ml), promoting a threefold increase in tissue permeability measured using FITC-dextran (4 kD) regardless of the intestinal region, thus suggesting an alteration in intestinal permeability at high bile salt concentrations. The findings from our study emphasize the importance of considering intestinal function when contemplating the possible use of a particular bile salt as a dietary supplement. It appears that bile salts, whether acting individually or in combination, play a pivotal role in orchestrating nutrient absorption by influencing the function of epithelial ion transport. However further research is needed to fully grasp the region-dependent nuances of bile salt effects on ion transport and the ultimate consequences for nutrient absorption in the context of fish aquaculture.
- A new species of Pontocrates Boeck, 1871 (Crustacea, Amphipoda, Oedicerotidae) from CyprusPublication . GARCIA GÓMEZ, SERGIO C.; MYERS, ALAN A.; AVRAMIDI, ELENI; GRAMMATIKI, KLEOPATRA; Lymperaki, Myrsini; RESAIKOS, VASILIS; PAPATHEODOULOU, MAGDALENE; LOUCA, VASILIS; XEVGENOS, DIMITRIOS; KÜPPER, FRITHJOF C.A new species of the amphipod genus Pontocrates (Boeck 1871), family Oedicerotidae, is described from Cyprus in the south-eastern Mediterranean Sea. It is a sister taxon to Pontocrates moorei (Myers & Ashelby 2022), currently recorded solely from the British Isles. It is the third species of Pontocrates now known to occur in the Mediterranean Sea.
- Artificial Intelligence and sustainable tourism planning: a hetero-intelligence methodology proposalPublication . Buitrago-Esquinas, Eva Maria; Yñiguez-Ovando, Rocío; Puig-Cabrera, Miguel; Custódio Santos, Margarida; Santos, José António C.This study explores the growing significance of Large Language Models (LLMs) in tourism, for their current and potential applications. It aims to achieve two primary objectives: first, to develop a novel heterointelligence framework merging human and artificial intelligence (AI) to address contemporary sustainability challenges in tourism; second, to validate this framework by applying it to sustainable tourism planning, assessing LLMs' capabilities and limitations. The research employs a hetero-intelligence performance test, contrasting human intelligence and AI contributions in sustainable tourism planning with overtourism as a proxy challenge. Results showed that hetero-intelligence could effectively address sustainability issues in tourism, provided human and AI strengths and weaknesses are understood. LLMs proved useful in diagnosing and proposing solutions for sustainability-related issues. However, a rigorous methodological framework is essential to ensure unbiased outcomes. The research offers practical guidelines for applying this approach and significantly contributes to epistemological and empirical dimensions, providing valuable insights for researchers and tourism planners. The study calls for more empirical research to validate the methodology and explore ethical and legal dimensions, extending hetero-intelligence applications to broader sustainability challenges in tourism.
- Establishment of a genetic resource bank for restocking management in Portuguese oyster (Crassostrea angulata) and striped venus clam (Chamelea gallina)Publication . Anjos, Catarina Miranda Castilho dos; Cabrita, Elsa; Matias, DomitíliaBivalves are essential for fisheries, aquaculture, and ecosystems, serving as nutrient-rich resources for human consumption. Despite their significance, many bivalve resources, including Crassostrea angulata (Portuguese oyster) and Chamelea gallina (striped venus clam) in Europe, evidence signs of depletion due to environmental change, anthropogenic impact, and overexploitation, requiring rehabilitation measures. One possible strategy involves establishing a genetic resource bank via cryopreservation. However, cryopreservation presents challenges, requiring optimization of freezing and thawing conditions, particularly the cryoprotectant solution, and understanding cryodamage. The present thesis aims to explore and establish conditions to store and preserve the genetic resources of C. angulata and C. gallina populations. Chapter 1 provides contextual background, on the current situation of bivalve production and the importance of these resources, with special attention on the endangered and valuable species for aquaculture/fisheries, C. angulata and C. gallina. The chapter addresses the fundamental principles of cryobiology and current knowledge on bivalve cryopreservation methodologies for sperm and larvae. This chapter discusses the value of cryodamage assessment tools, emphasizing “omics” molecular tools for high-potential analysis. Chapters 2 and 3 aim to optimize and develop new cryopreservation protocols for the target species. Chapter 2 investigates the effect of the cryoprotectant supplementation with sugars (trehalose and sucrose) on the post-thaw sperm quality of C. angulata. Several methodologies not commonly used in bivalve cryopreservation works were employed, including the determination of reactive oxygen species levels, acrosome integrity and the activity of antioxidant enzymes (superoxide dismutase - SOD, glutathione reductase - GR and glutathione peroxidase - GPX). Sugars supplementation, especially trehalose reduced lipid peroxidation and ROS levels having a positive effect in plasma membrane and acrosome integrity. Chapter 3 evaluates the larval quality of C. angulata and C. gallina exposed and cryopreserved with cryoprotectant solutions that differ in the permeant agent (dimethyl sulfoxide - DMSO and ethylene glycol - EG). The work aimed to understand the effects of cryoprotectant exposure and, cryopreservation on malformations, movement, and enzymatic activity compared with non-exposed larvae. The methodologies for cryopreserving D-larvae of both species were established for the first time. Chapter 4 investigates C. angulata D-larvae cryodamage during cryoprotectant exposure and cryopreservation, using RNA sequencing. This molecular approach was essential for providing evidence that the freezing process was the critical step rather exposure. Furthermore, identified 11 genes as relevant biomarkers of freezability for D-larvae quality assessment. This thesis presents strategies for cryopreserving the genetic material of C. angulata and C. gallina and for cryodamage evaluation.