Effect of amino acid supplementation and stress on expression of molecular markers in meagre (Argyrosomus regius)

The objectives of this work were: 1) develop of molecular stress biomarkers obtaining sequence data of different transcripts, 2) study the molecular stress response through the expression quantification of key gene involved in it, and 3) assess the effects of dietary amino acid additives on stress response in meagre meagres (Argyrososmus regius). Fish batches were fed two experimental diets with tryptophan (Trp) or aspartate (Asp) added for seven days. Before sampling fish were submitted to confinement/netting stress during 1 h, except control fish. Therefore fish were sampled before and after stress (1 h and 6 h post-stress). The sampling consisted of blood and tissues (brain, hypophysis and liver). Several gene expressions related to the stress response were measured in those tissues, and the cloning of corticotropin-releasing hormone (crh), corticotropin-releasing hormone binding protein (crh-bp), and thyrotropin-releasing hormone (trh) has been reported in meagre for the first time. In fact, fish fed an additional Asp diet did not present any sl, prl and gh expression changes, as for the control group. Contrarily, the Trp diet altered the prl and gh expressions after stress. For crh and crh-bp expressions, no significant differences were detected within the Asp diet hence that amino acid improved the stress response. However, Asp feeding, but not Trp, enhanced pomc-a expression after stress. Hsp70 expression varied for every treatment, including the control feeding, indicating a late response at 6 h post-stress sampling, where both Asp and Trp treatments increased these expressions significantly. Concluding, the response of molecular stress markers to amino acid enriched diets was diverse. The stressor did not change significantly the relative expression of most analyzed genes for control feeding groups, though the Asp supplemented diet was more effective for attenuating molecular markers than the Trp one.info:eu-repo/semantics/publishedVersio

What can we learn from glucocorticoid administration in fish? Effects of cortisol and dexamethasone on intermediary metabolism of gilthead seabream (Sparus aurata L.)

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Teleost fish survival and physiological recovery after capture by hookline: the case study of the blackspot seabream (Pagellus bogaraveo)

Evaluating the survival of discarded species is gaining momentum after the new European Common Fisheries Policy (Article 15 of the European Regulation No. 1380/2013). This regulation introduced a discard ban, with an exemption for those species with demonstrated high survival rates after their capture and release. Candidate species should be evaluated for each fishing gear and geographical area. In this study, we assessed not only survival, but also physiological recovery rates of blackspot seabream (Pagellus bogaraveo) below commercial size captured with a hookline called “voracera” in the Strait of Gibraltar (SW Atlantic waters of Europe). Experiments onboard a commercial fishing vessel were paralleled with studies in controlled ground-based facilities, where the capture process was mimicked, and physiological recovery markers were described. Our results confirmed that hookline capture induced acute stress responses in the target species, such as changes in plasma cortisol, lactate, glucose, and osmolality. However, 90.6% of the blackspot seabreams below commercial size captured with this fishing gear managed to survive, and evidenced physiological recovery responses 5 h after capture, with complete homeostatic recovery occurring within the first 24 h. Based on this study, the European Commission approved an exemption from the discard (EU Commission Delegated Regulation 6794/2018). Thus, the robust methodology described herein can be an important tool to mitigate the problem of discards in Europe.Postprin

Intestinal response to salinity challenge in the Senegalese sole (Solea senegalensis)

Fish are continuously forced to actively absorb or expel water and ions through epithelia. Most studies have focused on the gill due to its role in Na+ and Cl- trafficking. However, comparatively few studies have focused on the changing function of the intestine in response to external salinity. Therefore, the present study investigated the main intestinal changes of long-term acclimation of the Senegalese sole (Solea senegalensis) to 5,15, 38 and 55 ppt. Through the measurement of short-circuit current (Isc) in Ussing chambers and biochemical approaches, we described a clear anterior/posterior functional regionalization of the intestine in response to salinity. The use of specific inhibitors in Ussing chamber experiments, revealed that the bumetanide-sensitive Na+/K+/Cl- co-transporters are the main effectors of Cl- uptake in both anterior intestine and rectum. Additionally, the use of the anion exchanger specific inhibitor, DIDS, showed a salinity/region dependency of anion exchanger function. Moreover, we also described ouabain-sensitive Na+/K+-ATPase (NKA) and Bafilomycin Al-sensitive H-ATPase activities (HA), which displayed changes related to salinity and intestinal region. However, the most striking result of the present study is the description of an omeprazole-sensitive H+/K+-ATPase (HKA) in the rectum of Senegalese sole. Its activity was consistently measurable and increased at lower salinities, reaching rates even higher than those of the NKA. Together our results provide new insights into the changing role of the intestine in response to external salinity in teleost fish. The rectal activity of HKA offers an alternative/cooperative mechanism with the HA in the final processing of intestinal water absorption by apical titration of secreted bicarbonate. (C) 2016 Elsevier Inc. All rights reserved.Ministry of Science and Education, Spain [AGL2010-14876]Ministry of Science and Higher EducationEuropean Social Funds through the Portuguese National Science Foundation (FCT) [PTDC/MAR-BIO/3811/2012, PTDC/MAR-BIO/3034/2014]Portuguese Foundation for Science and Technology (FCT) [UID/Multi/04326/2013