1
|
Gou N, Wang K, Jin T, Yang B. Effects of Starvation and Refeeding on Growth, Digestion, Nonspecific Immunity and Lipid-Metabolism-Related Genes in Onychostoma macrolepis. Animals (Basel) 2023; 13:ani13071168. [PMID: 37048424 PMCID: PMC10093011 DOI: 10.3390/ani13071168] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2023] [Revised: 03/23/2023] [Accepted: 03/23/2023] [Indexed: 03/29/2023] Open
Abstract
The present research was conducted to assess the influences of starvation and refeeding on growth, nonspecific immunity and lipid metabolic adaptation in Onychostoma macrolepis. To date, there have been no similar reports in O. macrolepis. The fish were randomly assigned into two groups: control group (continuous feeding for six weeks) and starved鈥搑efed group (starvation for three weeks and then refeeding for three weeks). After three weeks of starvation, the results showed that the body weight (BW, 1.44 g), condition factor (CF, 1.17%), visceral index (VSI, 3.96%), hepatopancreas index (HSI, 0.93%) and intraperitoneal fat index (IPFI, 0.70%) of fish were significantly lower compared to the control group (BW, 5.72 g; CF, 1.85%; VSI, 6.35%; HSI, 2.04%; IPFI, 1.92%) (p < 0.05). After starvation, the serum triglyceride (TG, 0.83 mmol/L), total cholesterol (T-GHOL, 1.15 mmol/L), high-density lipoprotein (HDL, 1.13 mmol/L) and low-density lipoprotein (LDL, 0.46 mmol/L) concentrations were significantly lower than those in the control group (TG, 1.69 mmol/L; T-GHOL, 1.86 mmol/L; HDL, 1.62 mmol/L; LDL, 0.63 mmol/L) (p < 0.05). The activities of intestinal digestive enzymes (amylase, lipase and protease) in the starved-refed group were significantly lower than those in the control group after three weeks of starvation (p < 0.05). The highest activities of immune enzymes such as lysozyme (LZM), acid phosphate (ACP), alkaline phosphate (ALP), superoxide dismutase (SOD), glutathione peroxidase (GSH-PX) and catalase (CAT) in the hepatopancreas were presented in the starved鈥搑efed group at second week, and significantly higher than those in the control group (p < 0.05). Meanwhile, starvation significantly improved intestinal immune enzymes activities (p < 0.05). the lowest TG contents and the highest expression levels of lipolysis genes including hormone-sensitive lipase (HSL) and carnitine palmitoyl transferase 1 isoform A (CPT-1A) appeared in the hepatopancreas, muscle and intraperitoneal fat after starvation, indicating the mobilization of fat reserves in these tissues (p < 0.05). After refeeding, the recovery of TG content might be mediated by the upregulation of the expression levels of lipogenesis genes such as sterol regulatory element binding protein 1 (SREBP1) and fatty acid synthase (FAS). Understanding the duration of physiological and metabolic changes in O. macrolepis and their reversibility or irreversibility to supplementary feeding response could provide valuable reference for the adaptability of O. macrolepis in large-scale culturing, proliferation and release.
Collapse
|
2
|
Salamanca N, Moreno O, Gir谩ldez I, Morales E, de la Rosa I, Herrera M. Effects of Dietary Phenylalanine and Tyrosine Supplements on the Chronic Stress Response in the Seabream ( Sparus aurata). Front Physiol 2022; 12:775771. [PMID: 35222060 PMCID: PMC8864120 DOI: 10.3389/fphys.2021.775771] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2021] [Accepted: 10/25/2021] [Indexed: 01/18/2023] Open
Abstract
The increase of aquaculture production is associated with a growing interest in improving physiological status and welfare in fish. For this reason, the search for strategies for mitigating stress has been intensified, with one of these strategies being food supplementation with different amino acids (AA). The objective of this study was to evaluate the effects of dietary phenylalanine (Phe) and tyrosine (Tyr) supplements on the endocrine and physiological state of seabreams (Sparus aurata) subjected to chronic stress. The fish were stocked at 30 fish/tank in a recirculation aquatic system, fed one control diet and two diets supplemented with 5% Phe or Tyr for 90 days. Blood was drawn from 10 fish per tank every 30 days, and the weight and length were measured every 15 days. At the end of the experiment, length/weight of the fish were measured, and they were sacrificed for the extraction of blood, head kidney, liver, and brain. Classic plasma stress markers (glucose, lactate, proteins, and cortisol), as well as hormones derived from Phe and Tyr (adrenaline, norepinephrine, and dopamine) and the accumulation of AA were analyzed. Fish fed with diets supplemented with Phe or Tyr showed a reduction in various stress markers and physiological parameters. In addition, the stress condition favored a mobilization of AA toward the tissues, especially in supplemented diets, so this excess of AA could be used as an energy substrate to cope with stress.
Collapse
Affiliation(s)
| | | | | | - Emilio Morales
- Faculty of Experimental Sciences, University of Huelva, Huelva, Spain
| | | | - Marcelino Herrera
- IFAPA Centro Agua del Pino, Cartaya, Spain
- Escuela Superior de Ingenier铆a, University of Huelva, Huelva, Spain
| |
Collapse
|
3
|
Dietary Histidine, Threonine, or Taurine Supplementation Affects Gilthead Seabream ( Sparus aurata) Immune Status. Animals (Basel) 2021; 11:ani11051193. [PMID: 33919381 PMCID: PMC8143364 DOI: 10.3390/ani11051193] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2021] [Revised: 03/31/2021] [Accepted: 04/09/2021] [Indexed: 12/16/2022] Open
Abstract
Simple Summary The concept of supporting animal health through the best possible nutrition is well-accepted in modern aquaculture, and functional amino acids (AAs) appear to be good candidates to improve health and growth performance. For instance, histidine (His), taurine (Tau), and threonine (Thr) appear to play important roles in homeostatic maintenance, detoxification of reactive species, and immune function. The present study aimed to evaluate the effects of His, Tau, and Thr supplementation on the gilthead seabream (Sparus aurata) immune status. In general, the results suggest that dietary supplementation with His, Tau, or Thr above their nominal requirements for this species has relatively mild effects. Still, some effects of threonine and taurine supplementation on the fish immune system were observed, particularly after a short-term feeding period (four weeks), which reinforces the importance of feeding period when aiming to improve immune alertness. Hence, further studies with other supplementation levels and eventually duration of supplementation could help to clarify the potential immunomodulatory role of these AAs for gilthead seabream. Abstract AAs have become interesting feed ingredients to be used in functional fish feeds as not only are they protein building blocks, but they also participate in several other key metabolic processes. In the present study, a comprehensive analysis of transcriptomics, hematology, and humoral immune parameters (plasma and skin mucus) were measured twice over the course of the feeding trial (four weeks). Plasma antiprotease activity increased in fish fed Thr compared to those fed the CTRL and Tau treatments, regardless of sampling time. The bactericidal activity in skin mucus decreased in fish fed Tau and His treatments compared to those fed the CTRL diet after two weeks. The membrane IgT (mIgT) was upregulated in fish fed Tau after four weeks, while C-type lectin domain family domain 10 member (clec10a) was downregulated in fish fed Thr after two weeks of feeding. By comparing the molecular signatures of head-kidney by means of a PLS-DA, it is possible to visualize that the main difference is between the two sampling points, regardless of diet. Altogether, these results suggest that dietary supplementation with these AAs at the tested levels causes mild immune-modulation effects in gilthead seabream, which should be further studied under disease challenge conditions.
Collapse
|
4
|
Salamanca N, Gir谩ldez I, Morales E, de La Rosa I, Herrera M. Phenylalanine and Tyrosine as Feed Additives for Reducing Stress and Enhancing Welfare in Gilthead Seabream and Meagre. Animals (Basel) 2020; 11:ani11010045. [PMID: 33383663 PMCID: PMC7824165 DOI: 10.3390/ani11010045] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2020] [Revised: 12/21/2020] [Accepted: 12/23/2020] [Indexed: 01/15/2023] Open
Abstract
Simple Summary Food additives (phenylalanine and tyrosine) were tested in gilthead seabream (Sparus aurata) and meagre (Argyrosomus regius) to improve fish welfare in sea farms. These amino acids improved the stress response in both species, reducing some stress markers, though interspecific differences were detected. The results indicate that these dietary supplements could be provided before submitting fish to typical stress conditions in sea farms (sampling, grading, etc.) for improving animal welfare. Abstract Increased aquaculture production is associated with a growing interest in improving fish welfare. For this reason, the search for strategies to mitigate stress has intensified, one of these strategies being food supplementation with amino acids. The objective of this study was to evaluate the effects of dietary phenylalanine (Phe) and Tyrosine (Tyr) on the stress response and metabolism of juvenile gilthead seabreams (Sparus aurata) and meagres (Argyrosomus regius). Fish batches were fed a control diet and two diets supplemented with 5% Phe or Tyr for seven days. At the end of the experiment fish were stressed by air exposure for 3 min and then sacrificed for the extraction of blood and brain. Classical plasma stress markers were analyzed (glucose, lactate, proteins, cortisol), as well as hormones derived from those amino acids (adrenaline, noradrenaline and dopamine). Despite interspecific differences, fish fed the diets supplemented with Phe or Tyr showed a reduction on several stress markers. However, interspecific differences were detected for many indicators. Concretely, hormonal stress markers were significantly attenuated in meagres fed the enriched diets. Moreover, the stress condition favored a mobilization of amino acids towards the brain, especially in supplemented diets, hence this amino acid excess could be used as an energy substrate to cope with stress.
Collapse
Affiliation(s)
- Natalia Salamanca
- IFAPA Centro Agua del Pino, El Rompido-Punta Umbria rd., 21459 Cartaya, Spain;
- Correspondence: ; Tel.: +34-671532192
| | - Inmaculada Gir谩ldez
- Faculty of Experimental Sciences, University of Huelva, 21071 Huelva, Spain; (I.G.); (E.M.)
| | - Emilio Morales
- Faculty of Experimental Sciences, University of Huelva, 21071 Huelva, Spain; (I.G.); (E.M.)
| | - Ignacio de La Rosa
- Escuela Superior de Ingenier铆a, University of Huelva, 21071 Huelva, Spain;
| | - Marcelino Herrera
- IFAPA Centro Agua del Pino, El Rompido-Punta Umbria rd., 21459 Cartaya, Spain;
- Escuela Superior de Ingenier铆a, University of Huelva, 21071 Huelva, Spain;
| |
Collapse
|
5
|
Oxidation of energy substrates in tissues of largemouth bass (Micropterus salmoides). Amino Acids 2020; 52:1017-1032. [PMID: 32656621 DOI: 10.1007/s00726-020-02871-y] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2020] [Accepted: 07/03/2020] [Indexed: 12/12/2022]
Abstract
This study tested the hypothesis that amino acids are oxidized at higher rates than glucose and palmitate for ATP production in tissues of largemouth bass (LMB, a carnivorous fish). Slices (10 to 50 mg) of liver, proximal intestine, kidney, and skeletal muscle isolated from LMB were incubated at 26聽掳C for 2聽h in oxygenated Krebs-Henseleit bicarbonate buffer (pH 7.4, with 5聽mM D-glucose) containing either D-[U-14C]glucose, 2聽mM L-alanine plus L-[U-14C]alanine, 2聽mM L-aspartate plus L-[U-14C]aspartate, 2聽mM L-glutamate plus L-[U-14C]glutamate, 2聽mM L-glutamine plus L-[U-14C]glutamine, 2聽mM L-leucine plus L-[U-14C]leucine, or 2聽mM palmitate plus [U-14C]palmitate. In parallel experiments, tissues were incubated with a [U-14C]-labeled tracer and a mixture of unlabeled substrates [alanine, aspartate, glutamate, glutamine, leucine, and palmitate (2聽mM each) plus 5聽mM glucose]. 14CO2 was collected to calculate the rates of substrate oxidation. In separate experiments, O2 consumption by each tissue was measured in the presence of individual or a mixture of substrates. The activities of key metabolic enzymes were also measured. Results indicated that the liver and skeletal muscle had a limited ability to oxidize glucose and palmitate to CO2 for ATP production in the presence of individual or a mixture of substrates due to low activities of carnitine palmitoyltransferase-I, hexokinase and pyruvate dehydrogenase. In the presence of individual substrates, each amino acid was actively oxidized by all the tissues. In the presence of a mixture of substrates, glutamine and glutamate were the major metabolic fuels in the proximal intestine and kidney, as glutamine for the liver and aspartate for skeletal muscle. All the tissues had high activities of glutaminase, glutamate dehydrogenase, and transaminases. At the same extracellular concentration of amino acids (2 mM) in a mixture of energy substrates, glutamine was the major metabolic fuel for the liver of the LMB, glutamine and glutamate for the proximal intestine and kidneys, and aspartate for the skeletal muscle. Glutamine plus glutamate plus aspartate generated 60-70% of ATP in LMB tissues.
Collapse
|
6
|
Clark TC, Tinsley J, Sigholt T, Macqueen DJ, Martin SAM. Arginine, ornithine and citrulline supplementation in rainbow trout: Free amino acid dynamics and gene expression responses to bacterial infection. FISH & SHELLFISH IMMUNOLOGY 2020; 98:374-390. [PMID: 31968266 DOI: 10.1016/j.fsi.2020.01.026] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/04/2019] [Revised: 01/10/2020] [Accepted: 01/15/2020] [Indexed: 06/10/2023]
Abstract
Supplementing the diet with functional ingredients is a key strategy to improve fish performance and health in aquaculture. The amino acids of the urea and nitric oxide (NO) cycles - arginine, ornithine and citrulline - perform crucial roles in the immune response through the generation of NO and the synthesis of polyamine used for tissue repair. We previously found that citrulline supplementation improves and maintains circulating free arginine levels in rainbow trout more effectively than arginine supplementation. Here, to test whether supplementation of urea cycle amino acids modulates the immune response in rainbow trout (Oncorhynchus mykiss), we supplemented a commercial diet with high levels (2% of total diet) of either arginine, ornithine or citrulline during a 7-week feeding trial, before challenging fish with the bacterium Aeromonas salmonicida. We carried out two separate experiments to investigate fish survival and 24聽h post-infection to investigate the immediate response of free amino acid levels, and transcriptional changes in genes encoding urea cycle, NO cycle and polyamine synthesis enzymes. There were no differences in percentage fish mortality between diets, however there were numerous highly significant changes in free amino acid levels and gene expression to both dietary supplementation and infection. Out of 26 amino acids detected in blood plasma, 8 were significantly changed by infection and 9 by dietary supplementation of either arginine, ornithine or citrulline. Taurine, glycine and aspartic acid displayed the largest decreases in circulating levels in infected fish, while ornithine and isoleucine were the only amino acids that increased in concentration. We investigated transcriptional responses of the enzymes involved in arginine metabolism in liver and head kidney; transcripts for polyamine synthesis enzymes showed highly significant increases in both tissues across all diets following infection. The paralogous arginase-encoding genes, Arg1a, Arg1b, Arg2a and Arg2b, displayed complex responses across tissues and also due to diet and infection. Overall, these findings improve our understanding of amino acid metabolism following infection and suggests new potential amino acid targets for improving the immune response in salmonids.
Collapse
Affiliation(s)
- T C Clark
- School of Biological Sciences, University of Aberdeen, Tillydrone Avenue, Aberdeen, UK
| | - J Tinsley
- BioMar AS, Grangemouth Docks, Grangemouth, UK
| | | | - D J Macqueen
- The Roslin Institute and Royal (Dick) School of Veterinary Studies, University of Edinburgh, Edinburgh, UK
| | - S A M Martin
- School of Biological Sciences, University of Aberdeen, Tillydrone Avenue, Aberdeen, UK.
| |
Collapse
|
7
|
Asencio-Alcudia G, Andree KB, Giraldez I, Tovar-Ramirez D, Alvarez-Gonz谩lez A, Herrera M, Gisbert E. Stressors Due to Handling Impair Gut Immunity in Meagre ( Argyrosomus regius): The Compensatory Role of Dietary L-Tryptophan. Front Physiol 2019; 10:547. [PMID: 31133878 PMCID: PMC6523026 DOI: 10.3389/fphys.2019.00547] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2018] [Accepted: 04/17/2019] [Indexed: 01/14/2023] Open
Abstract
In the context of intensive aquaculture, meagre (Argyrosomus regius) is one of the most important new aquaculture species in Southern Europe and several studies are focused on the optimization of its culture. Nevertheless, stressors such as handling during transport or culture maintenance may affect the immune system, thereby impairing some immune responses or provoking cellular damage. One strategy that has been used to avert this type of negative stress response is the supplementation of amino acids to improve resistance to stress. In this experiment, meagre (105.0聽卤聽2.6聽g, mean聽卤聽standard deviation) juveniles were fed two diets for a period of 7聽days, the first a commercial diet supplemented with 1% tryptophan (Trp) and second, the same commercial diet without tryptophan supplementation (control group). The effects of two types of handling stressors (air exposure and confinement/netting) on fish fed both diets was evaluated in terms of gene expression of the selected gut immunity markers, such as (1) innate immune response processes: c3 complement (c3), lysozyme (lys), and cyclooxygenase (cox2); (2) humoral immune response processes: interferon type 1 (ifn1), mx protein (mxp), interleukin 1b (il-1b), tumor necrosis factor 1a (tnf1a), and interleukin 10 (il-10); (3) antimicrobial peptides: defensin (def), hepcidin (hep), piscidin (pis), and a marker for mitochondrial respiration: glyceraldehyde 3-phosphate dehydrogenase (gapdh). Samples of the anterior intestine were collected at 1 and 6聽h post-stress (hps). Results showed that in fish fed 1% Trp, the air exposure resulted in an upregulation of gene expression at 6 hps for c3, lys, cox2, ifn1, mxp, il-10 and gapdh, and il-1b and pis. The confinement/netting test for fish fed 1% Trp resulted in an upregulation of c3 and mxp and a downregulation of cox2, ifn1, il-1b, tnf1a, il-10, def, hep, and gapdh at both post-stress times (1 and 6 hps). According to the present study, dietary supplementation with 1% Trp may be considered as a proper nutritional strategy for improving tolerance and/or alleviating acute response to handling stressors.
Collapse
Affiliation(s)
- Gloria Asencio-Alcudia
- Centro de Investigaciones Biol贸gicas del Noroeste (CIBNOR), La Paz, Mexico.,Laboratorio de Acuicultura Tropical, Divisi贸n Acad茅mica de Ciencias Biol贸gicas, Universidad Ju谩rez Aut贸noma de Tabasco (DACBiol-UJAT), Villahermosa, Mexico
| | - Karl B Andree
- Programa de Cultius Aqu脿tics, IRTA, Centro de San Carlos de la R脿pita (IRTA-SCR), Tarragona, Spain
| | | | | | - Alfonso Alvarez-Gonz谩lez
- Laboratorio de Acuicultura Tropical, Divisi贸n Acad茅mica de Ciencias Biol贸gicas, Universidad Ju谩rez Aut贸noma de Tabasco (DACBiol-UJAT), Villahermosa, Mexico
| | | | - Enric Gisbert
- Programa de Cultius Aqu脿tics, IRTA, Centro de San Carlos de la R脿pita (IRTA-SCR), Tarragona, Spain
| |
Collapse
|
8
|
Herrera M, Mancera JM, Costas B. The Use of Dietary Additives in Fish Stress Mitigation: Comparative Endocrine and Physiological Responses. Front Endocrinol (Lausanne) 2019; 10:447. [PMID: 31354625 PMCID: PMC6636386 DOI: 10.3389/fendo.2019.00447] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/12/2018] [Accepted: 06/20/2019] [Indexed: 01/01/2023] Open
Abstract
In the last years, studies on stress attenuation in fish have progressively grown. This is mainly due to the interest of institutions, producers, aquarists and consumers in improving the welfare of farmed fish. In addition to the development of new technologies to improve environmental conditions of cultured fish, the inclusion of beneficial additives in the daily meal in order to mitigate the stress response to typical stressors (netting, overcrowding, handling, etc.) has been an important research topic. Fish are a highly diverse paraphyletic group (over 27,000 species) though teleost infraclass include around 96% of fish species. Since those species are distributed world-wide, a high number of different habitats and vital requirements exist, including a wide range of environmental conditions determining specifically the stress response. Although the generalized endocrine response to stress (based on the release of catecholamines and corticosteroids) is detectable and therefore provides essential information, a high diversity of physiological effects have been described depending on species. Moreover, recent omics techniques have provided a powerful tool for detecting specific differences regarding the stress response. For instance, for transcriptomic approaches, the gene expression of neuropeptides and other proteins acting as hormonal precursors during stress has been assessed in some fish species. The use of different additives in fish diets to mitigate stress responses has been deeply studied. Besides the species factor, the additive type also plays a pivotal role in the differentiation of the stress response. In the literature, several types of feed supplements in different species have been assayed, deriving in a series of physiological responses which have not focused exclusively on the stress system. Immunological, nutritional and metabolic changes have been reported in these experiments, always associated to endocrine processes. The biochemical nature and physiological functionality of those feed additives strongly affect the stress response and, in fact, these can act as neurotransmitters or hormone precursors, energy substrates, cofactors and other essential elements, implying multi-systematic and multi-organic responses. In this review, the different physiological responses among fish species fed stress-attenuating diets based on biomolecules and minerals have been assessed, focusing on the endocrine regulation and its physiological effects.
Collapse
Affiliation(s)
- Marcelino Herrera
- IFAPA Centro Agua del Pino, Huelva, Spain
- *Correspondence: Marcelino Herrera
| | - Juan Miguel Mancera
- Department of Biology, Faculty of Marine and Environmental Sciences, Campus de Excelencia Internacional del Mar (CEI路MAR), Instituto Universitario de Investigaci贸n Marina (INMAR), Universidad de C谩diz, C谩diz, Spain
| | - Benjam铆n Costas
- Centro Interdisciplinar de Investiga莽茫o Marinha e Ambiental (CIIMAR), Matosinhos, Portugal
- Instituto de Ci锚ncias Biom茅dicas Abel Salazar (ICBAS-UP), Universidade do Porto, Porto, Portugal
| |
Collapse
|
9
|
Narrowing the Range of Environmental Salinities Where Juvenile Meagre (Argyrosomus regius) Can Be Cultured Based on an Osmoregulatory Pilot Study. FISHES 2018. [DOI: 10.3390/fishes3040048] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Aquaculture in Europe aims to diversify and optimize fish farming. The meagre (Argyrosomus regius) arose as a promising species due to its fast growth rates and flesh quality. Thus, it is currently being produced in several Mediterranean countries, mainly in sea-cages and salt-marshes. However, although meagre naturally spend the first years of life in brackish waters, to date it is cultured in seawater. Here, we show that juveniles may not successfully face either freshwater or hyper-osmotic environments as high as 55 ppt salinity. We found that 55 ppt induced catabolism and mobilization of energy metabolites stored in the liver, probably to maintain its osmotic balance. Furthermore, we found that osmoregulatory tissues such as gills managed to maintain plasma osmolality levels without differences in meagre acclimated at 5, 12 and 39 ppt salinity. Our results demonstrate the euryhaline capacity of this species, highlighting that juveniles may be cultured in a wider range of salinities rather than just at seawater. Future studies should focus on optimal environmental salinities for the growth of A. regius juveniles, including long-term experiments limited to the range of 5 ppt to full-strength seawater. Minimizing fish energy consumption in osmoregulation could be economically beneficial for the aquaculture industry in Europe.
Collapse
|