Suchergebnisse

Trabajo presentado en el XII Conference of the Iberian Association for Comparative Endocrinology (AIEC), celebrado en Faro (Portugal), del 26 al 28 de septiembre de 2019. ; Cortisol is the most important hormone involved in the regulation of neuroendocrine stress response in teleosts. Effects of this hormone are mediated through its intracellular receptors, although membrane components are also involved, with unclear roles during the stress response. In this work, the contribution of membrane-initiated cortisol actions on stress-related parameters and metabolism-related genes in gilthead sea bream (Sparus aurata) were evaluated. Two in vivo experiments were performed. In the first, fish were administered with vehicle, BSA, cortisol and cortisol-BSA (membrane impermeable analogue) dissolved in saline (PBS 1X). In the second, the same treatments were replicated but using coconut oil as a vehicle. Fish were sampled after one and six hours (first experiment) and after three days (second experiment). Plasma cortisol, glucose and lactate levels were measured, and hepatic transcript levels of key genes involved in glucose metabolism, like glucose-6-phosphatase (g6pc), phosphoglycerate mutase 1 (pgam1), among others, were also analyzed. Fish implanted with each version of cortisol in both in vivo experiments reached plasma levels typically observed under an acute stress in S. aurata. Cortisol and cortisol-BSA increased glucose and lactate plasma levels after six hours of treatment. However, cortisol, but not cortisol-BSA, maintained increased plasma glucose levels after three days of treatment. Analysis by qPCR showed that expression of g6pc increased after one hour of cortisol and cortisol-BSA administration. However, cortisol, but not cortisol-BSA, maintained the g6pc up-regulation after three days. Our results suggested that membrane-initiated cortisol actions contributed to the regulation of early metabolic adaptations in S. aurata submitted to an emulated acute stress situation. ; This work was funded by Spanish Ministry of Science, Innovation and Universities - MICINN (AGL2016-76069-C2-1-R) awarded to JMM. The authors belong to the Fish Welfare and Stress Network (AGL2016-81808-REDT), supported by the Agencia Estatal de Investigación (MICINN, Spanish Government). ; Peer reviewed

Transport processes between aquaculture facilities activate the stress response in fish. To deal with these situations, the hypothalamic-pituitary-interrenal (HPI) axis releases cortisol, leading to an increase in circulating energy resources to restore homeostasis. However, if the allostatic load generated exceeds fish tolerance limits, stress-related responses will compromise health and welfare of the animals. In this context, anesthetics have arisen as potential agents aiming to reduce negative effects of stress response. Here we assessed the effects of a sedative dose of clove oil (CO) and MS-222 on hallmarks involved in HPI axis regulation and energy management after simulated transport, and further recovery, in gilthead seabream (Sparus aurata L.) juveniles. Fish were placed in a mobile setup of water tanks where transport conditions were simulated for 6 h. Sedation doses of either CO (2.5 mg L−1) or MS-222 (5 mg L−1) were added in the water tanks. A control group without anesthetics was also included in the setup. Half of the animals (n = 12 per group) were sampled immediately after transport, while remaining animals were allowed to recover for 18 h in clean water tanks and then sampled. Our results showed that the HPI axis response was modified at peripheral level, with differences depending on the anesthetic employed. Head kidney gene-expressions related to cortisol production (star and cyp11b1) matched concomitantly with increased plasma cortisol levels immediately after transport in CO-sedated fish, but these levels remained constant in MS-222-sedated fish. Differential changes in the energy management of carbohydrates, lipids and amino acids, depending on the anesthetic employed, were also observed. The use of CO stimulated amino acids catabolism, while MS-222-sedated fish tended to consume liver glycogen and mobilize triglycerides. Further studies, including alternative doses of both anestethics, as well as the assessment of time-course HPI activation and longer recovery periods, are necessary to better understand if the use of clove oil and MS-222 is beneficial for S. aurata under these circumstances. ; This work was funded by Spanish Ministry of Science, Innovation and Universities - MICINN (AGL2013-48835-C2-1-R and AGL2016-76069-C2-1-R) awarded to JM. IJ-C is currently supported by a contract of Trainee Predoctoral Research Staff from the University of Cádiz (PIF UCA/REC02VIT/2014; 2018-011/PU/AY.PUENTE/CD). The authors (IJ-C, IR-J, JM-S, and JM) belong to the Fish Welfare and Stress Network (AGL2016-81808-REDT), supported by the Agencia Estatal de Investigación (MICINN, Spanish Government).

Thyroid hormones are involved in many developmental and physiological processes, including osmoregulation. The regulation of the thyroid system by environmental salinity in the euryhaline gilthead seabream (Sparus aurata) is still poorly characterized. To this end seabreams were exposed to four different environmental salinities (5, 15, 40 and 55 ppt) for 14 days, and plasma free thyroid hormones (fT3, fT4), outer ring deiodination and Na+/K+-ATPase activities in gills and kidney, as well as other osmoregulatory and metabolic parameters were measured. Low salinity conditions (5 ppt) elicited a significant increase in fT3 (29%) and fT4 (184%) plasma concentrations compared to control animals (acclimated to 40 ppt, natural salinity conditions in the Bay of Cádiz, Spain), while the amount of pituitary thyroid stimulating hormone subunit β (tshb) transcript abundance remained unchanged. In addition, plasma fT4 levels were positively correlated to renal and branchial deiodinase type 2 (dio2) mRNA expression. Gill and kidney T4-outer ring deiodination activities correlated positively with dio2 mRNA expression and the highest values were observed in fish acclimated to low salinities (5 and 15 ppt). The high salinity (55 ppt) exposure caused a significant increase in tshb expression (65%), but deiodinase gene expression (dio1 and dio2) and activity did not change and were similar to controls (40 ppt). In conclusion, acclimation to different salinities led to changes in the peripheral regulation of thyroid hormone metabolism in seabream. Therefore, thyroid hormones are involved in the regulation of ion transport and osmoregulatory physiology in this species. The conclusions derived from this study may also allow aquaculturists to modulate thyroid metabolism in seabream by adjusting culture salinity. ; This work was partially supported by a Socrates/Erasmus Grant from the European Union and a Ph.D. scholarship from the University of Cadiz (UCA 2009-074-FPI) to I. R-J. It has been also supported by grants AGL2007-61211/ACU (Ministerio de Educación y Ciencia and FEDER, Spain) and Proyecto de Excelencia PO7-RNM-02843 (Junta de Andalucía) to J.M.M. BL (SFRH/BPD/89889/2012) and PISP (SFRH/BPD/84033/2012) were supported by the Science Foundation (FCT) of Portugal. ; Peer reviewed

The potential for exemption from the European Union (EU) Common Fisheries Policy's (CFP) landing obligation (discard ban), where high discard survival can be demonstrated, has identified the need for scientific guidelines to conduct discard survival assessments. Robust estimates of discard survival can be used to justify exemptions from the landing obligation and inform on levels of post-release fishing mortality, which can then be accounted for in stock assessments. The Working Group on Methods for Estimating Discard Survival (WGMEDS) set out to review and update ICES guidance on Methods to Estimate Discard Survival and complete meta-analyses of discard survival evidence to investigate variables influencing survival, with a view to influencing survival through modified fishing practices. We also explored the demand for ongoing monitoring requirements to inform on discard survival and took a proactive approach to sharing discard survival estimates with those working in stock assessment so that new evidence could be applied more widely. In the past three years, the considerable investment in research in to discard survival, specifically from EU countries, has continued. The main outputs from WGMEDS include enhancements to the ICES guidance on how to quantify discard survival. This has supported the work of group members to estimate discard survival in a variety species-fishery combinations, including Nephrops, mackerel, plaice, common sole, eels, rays, much of which has been put forward as evidence to support exemptions from the EU discard ban. A critical review framework developed by WGMEDS has been used by the EU Scientific, Technical and Economic Committee for Fisheries (STECF) to assess the quality of discard survival evidence for proposed exemptions. There has been a high impact of work produced by the members of the group – specifically in multiple new EU regulated exemptions from the landing obligation. This has permitted fishers to continue discarding defined species and so assisting the implementation of the EU discard ban. Future work is expected to focus on applying discard survival estimates in stock assessments. This would include developing guidance to assist assessment expert groups to determine whether available survival studies can be applied. It would require reviewing and assessing the quality and confidence in available discard survival estimates and exploring the potential to combine the results of survival studies so the effect of different variables could be accounted for in estimating an overall best survival estimate. Ultimately, we would aim to include estimates of discard survival in catch scenarios in the ICES advice sheets.