Impact of dietary phosphorus on turbot bone mineral density and content

Fish are largely dependent on dietary phosphorus for skeletal development and mineralization. In aquaculture, commercial diets commonly have higher phosphorus concentration than the basal requirements in most fish species to ensure growth and prevent bone mineral disorders. Excessive phosphorus in feeds is harmful for metabolism and results in an increase of wastes in farm effluents, which impact aquatic ecosystems. Previous studies have shown that depletion/excess of dietary phosphorus cause skeletal malformations and reduced/enhanced mineralization in fish. There is scarce information on dietary phosphorus requirements for optimal bone mineralization in species with different types of bone (cellular vs. acellular bone), which is particularly relevant for sustainable aquaculture. Thus, the aim of our study was to analyse the effect of dietary phosphorus concentrations on bone mineralization of turbot, a demersal acellularâ boned fish and valuable aquaculture species. Our results show that the dietary phosphorus concentration did not cause changes to the bone mineral density and the phosphate/calcium concentrations. No apparent skeletal malformations were detected. Additionally, we did not find an altered expression of genes involved in bone mineral metabolism. Taken together, our data show that the phosphorus requirements for optimum growth and bone mineralization in turbot are below those currently used commercially at least for the time period examined: 55â 195 days postfertilization (dpf).Spanish Economy and Competitiveness Ministry project AGL2014-52473R and AGL2017-89648P to JR. PS-B was supported by AGL2014-52473R and AGL2017-89648P project contracts

Environmental DNA (eDNA) for monitoring marine mammals: Challenges and opportunities

Monitoring marine mammal populations is essential to permit assessment of population status as required by both national and international legislation. Traditional monitoring methods often rely on visual and/or acoustic detections from vessels and aircraft, but limitations including cost, errors in the detection of some species and dependence on taxonomic expertise, as well as good weather and visibility conditions often limit the temporal and spatial scale of effective, long-term monitoring programs. In recent years, environmental DNA (eDNA) has emerged as a revolutionary tool for cost-effective, sensitive, noninvasive species monitoring in both terrestrial and aquatic realms. eDNA is a rapidly developing field and a growing number of studies have successfully implemented this approach for the detection and identification of marine mammals. Here, we review 21 studies published between 2012 and 2021 that employed eDNA for marine mammal monitoring including single species detection, biodiversity assessment and genetic characterization. eDNA has successfully been used to infer species presence (especially useful for rare, elusive or threatened species) and to characterize the population genetic structure, although additional research is needed to support the interpretation of non-detections. Finally, we discuss the challenges and the opportunities that eDNA could bring to marine mammal monitoring as a complementary tool to support visual and acoustic methods

Molecular cloning and characterization of the matricellular protein Sparc/osteonectin in flatfish, Scophthalmus maximus, and its developmental stage-dependent transcriptional regulation during metamorphosis

SPARC/osteonectin is amultifunctionalmatricellular glycoprotein,which is expressed in embryonic and adult tissues that undergo active proliferation and dynamic morphogenesis. Recent studies indicate that Sparc expression appears early in development, although its function and regulation during development are largely unknown. In this report, we describe the isolation, characterization, post-embryonic developmental expression and environmental thermal regulation of sparc in turbot. The full-length turbot sparc cDNA contains 930 bp and encodes a protein of 310 amino acids, which shares 77, 75 and 80% identity with human, frog and zebrafish, respectively. Results of whole-mount in situ hybridization reveal a dynamic expression profile during post-embryonic turbot development. Sparc is expressed differentially in the cranioencephalic region; mainly in jaws, branchial arches, fin folds and rays of caudal, dorsal and anal fins. Furthermore, ontogenetic studies demonstrated that Sparc gene expression is dynamically regulated during post-embryonic turbot development, with high expression during stage-specific post-embryonic remodeling. Additionally, the effect of thermal environmental conditions on turbot development and on ontogenetic sparc expression was evaluated.En prens

Genetic and molecular analysis of phosphorus homeostasis regulatory genes. A key nutrient for aquaculture sustainability

Spanish Science and Innovation Ministry project [ALG2011-23581]Campus Do Mar-Xunta de Galicia PhD fellowshipinfo:eu-repo/semantics/publishedVersio

Feeding European sea bass (Dicentrarchus labrax) juveniles with a functional synbiotic additive (mannan oligosaccharides and Pediococcus acidilactici): An effective tool to reduce low fishmeal and fish oil gut health effects?

11 pages, 4 figures, 7 tablesThe aim of this study was to assess the effects of dietary mannan oligosaccharides (MOS), Pediococcus acidilactici or their conjunction as a synbiotic in low fish meal (FM) and fish oil (FO) based diets on European sea bass (Dicentrarchus labrax) disease resistance and gut health. For that purpose, sea bass juveniles were fed one of 6 diets containing different combinations of MOS (Biomos® and Actigen©; Alltech, Inc., Kentucky, USA) and Pediococcus acidilactici (BAC, Bactocell®; Lallemand Inc., Cardiff, UK) replacing standard carbohydrates as follows (MOS (%)/BAC (commercial recommendation): high prebiotic level (HP) = 0.6/0, low prebiotic level (LP) = 0.3/0, only probiotic (B) = 0/+, high prebiotic level plus probiotic (HPB) = 0.6/+, low prebiotic level plus probiotic (LPB) = 0.3/+, control (C) = 0/0 for 90 days. After 60 and 90 days of feeding trial, fish were subjected to an experimental infection against Vibrio anguillarum. Additionally, inducible nitric oxide synthase (iNOS) and tumor necrosis factor α (TNFα) gut patterns of immunopositivity and major histocompatibility complex class II (MHCII), transforming growth factor β (TGF-β), regulatory T-cell subset (CD4+T lymphocytes) and effector T cell (CD8α+ T lymphocytes) gene expression patterns in gut by in situ hybridization were evaluated after 90 days of feeding. The effects of both additives on posterior gut through Gut Associated Lymphoid Tissue (GALT) gene expression was also studied. Fish fed the prebiotic and its combination with P. acidilactici presented increased weight regardless of the dose supplemented after 90 days of feeding, however no effect was detected on somatic indexes. For posterior gut, morphometric patterns and goblet cells density was not affected by MOS, P. acidilactici or its combination. Anti-iNOS and anti-TNFα gut immunopositivity patterns were mainly influenced by MOS supplementation and not by its combination with P. acidilactici. MHCII-β, TCR-β, CD4 and CD8-α positive cells distribution and incidence was not affected by diet. Fish fed HP dose presented a clear up-regulation of TNF-α, cyclooxygenase-2 (COX-2), CD4 and IL10, whereas P. acidilactici dietary supplementation increased the number of interleukin-1β (IL1β) and COX-2 gene transcripts. Synbiotic supplementation resulted in a reduction of MOS-induced gut humoral proinflammatory response by increasing the expression of some cellular-immune system related genes. Fish mortality after V. anguillarum infection was reduced in fish fed LPB and LP diets compared to fish fed the non-suppelmented diet after 90 days of feeding. Thus, overall pointing to the combination of a low dose of MOS and P. acidilactici as synbiont (LPB) as a viable tool to potentiate European sea bass juvenile's growth and disease resistance when supplemented in low FM and FO diets.This work was funded by the Spanish Ministry of Economy and Competitiveness (MINECO, “Subprograma de proyectos de investigación fundamental no orientada, call 2012”) by the PROINMUNOIL (AGL2012-39919) project: “Functional additives & alternative oils to fish oils in Aquaculture: an effective tool increase fish disease resistance”. We also acknowledge the complementary funding through a ULPGC predoctoral and postdoctoral fellowships for FR and ST. SBP and RJ were supported by the Spanish Economy and Competitiveness Ministry project AGL2014-52473R.Peer reviewe