Suchergebnisse

8º Congreso Asociación Ibérica de Endocrinología Comparada (AIEC), Madrid, 5-7 septiembre, 2011. ; Gilthead sea bream (S. aurata) is a eurihaline fish, and therefore presents the capacity to live under different environmental salinities, expending extra energy for maintaining the homeostasis when there are osmotic differences between the internal medium and the external environment. In fish, glucose has a relevant role in osmotic stress, supplying the necessary extra energy to the osmoregulatory organs. This metabolite is a hydrophilic molecule that needs a specific transporter (GLUT) to cross plasma membrane. Several members of the GLUT family have been cloned in various fish species, but not in S. aurata. In this study we have cloned the S. aurata GLUT1 (saGLUT1). The cDNA is composed by 4483 bp, with a 5¿UTR of 173 bp, ORF 1476 bp and 3¿UTR which has 2616 bp, presenting high similarity to GLUT1 in other fish species (between 79 to 95 % identity). In addition, saGLUT1 mRNA expression changes in gills, kidney, liver and brain were determined by real time PCR analysis in specimens of 100-150 g body weight, acclimated to four different salinities (5, 12, 40 and 55 ppt) during 15 days. The major levels of expression were found in brain and gills (5000 and 8000 copies/10 ng RNA). Statistical differences in gills (highest expression at 40 ppt) and kidney (highest expression at 5 ppt) were detected, without any significant changes in brain and liver. Our results show that saGLUT1 mRNA expression is regulated in osmoregulatory organs in response to different environmental salinities ; CB-A is supported by a postdoctoral fellowship "Becas Chile" from Chile Government. JAM-S is supported by a Ph.D. fellowship (FPU) from (he Spanish Ministry of Education. ; Peer Reviewed

Trabajo presentado en el XIII Congreso de la Asociación Ibérica de Endocrinología Comparada, celebrado los días 16 y 17 de septiembre de 2021 ; Corticosteroids control inter alia, metabolism, immunology, osmoregulation, and stress responses. In the present work, we examined the different physiological and molecular responses evoked in the gilthead seabream acclimated to seawater (SW, 38 ppt) after chronic oral administration for 30 days of cortisol (F; 400 mg/kg fish feed) and the synthetic glucocorticoid dexamethasone (DEX; 300 mg/kg fish feed), prior- and post-hypersaline seawater (HSW, 60 ppt) direct transfer for 3 days. After the feeding trial, plasma cortisol levels showed the following pattern: CT > F > DEX. HSW transfer significantly enhanced plasma cortisol levels in the CT group, whereas F and DEX groups showed about half of these values. Na+/K+-ATPase (NKA) activity increased dramatically in the DEX group prior to HSW transfer. Surprisingly gill NKA activity levels in this tissue were recovered to the initial lowest levels for all the groups. Plasma and intestinal fluid osmolalities enhanced significantly after HSW transfer in the DEX group. Intestinal short circuit-current (Isc) showed a more anion absorptive capacity in the posterior intestine (PI) than the anterior. Moreover, F treatment significantly increased this anion absorptive capacity in the PI after HSW transference. Surprisingly HSW significantly decreased the anion absorptive capacity in all intestinal regions, specifically in the PI, indicating the appearance and/ or switch to secretory mechanisms in the intestine to counteract hypersalinity. Furthermore, molecular hypophyseal markers such as the pomcb and the gh were significantly altered/modulated by both pharmacological treatments and HSW challenge. ; This work was funded by Agencia Estatal de Investigación (Ministerio de Ciencia e Investigación, Spanish Government) (PID2020-117557RB-C22). A. Barany was supported by the University of Cadiz Ph.D. scholarship (UCA/REC01VI/2017).

Aflatoxin B1 (AFB1) is a mycotoxin often present in food. This study aimed to understand the physiological effects of AFB1 on the seabream (Sparus aurata) gastrointestinal system. In a first in vitro approach, we investigated ion transport using the short-circuit current (Isc) technique in Ussing chambers in the anterior intestine (AI). Application of apical/luminal AFB1 concentrations of 8 and 16 μM to healthy tissues was without effect on tissue transepithelial electrical resistance (TER), and apparent tissue permeability (Papp) was measured using fluorescein FITC (4 kD). However, it resulted in dose-related effects on Isc. In a second approach, seabream juveniles fed with different AFB1 concentrations (1 and 2 mg AFB1 kg fish feed) for 85 days showed significantly reduced gill Na/K-ATPase (NKA) and H-ATPase (HA) activities in the posterior intestine (PI). Moreover, dietary AFB1 modified Isc in the AI and PI, significantly affecting TER in the AI. To understand this effect on TER, we analyzed the expression of nine claudins and three occludins as markers of intestinal architecture and permeability using qPCR. Around 80% of the genes presented significantly different relative mRNA expression between AI and PI and had concomitant sensitivity to dietary AFB1. Based on the results of our in vitro, in vivo, and molecular approaches, we conclude that the effects of dietary AFB1 in the gastrointestinal system are at the base of the previously reported growth impairment caused by AFB1 in fish. ; This work was funded by the Spanish Ministry of Economy and Business-MINECO (AGL2016-76069-C2-1-R) awarded to JM. The authors (AB and JM) belong to the Fish Welfare and Stress Network (AGL2016-81808-REDT), supported by the Agencia Estatal de Investigación (MINECO, Spanish Government). AB was supported by the University of Cadiz Ph.D. scholarship (PIF UCA/REC02VIT/2014). CCMar is supported by national funds from the Portuguese Foundation for Science and Technology (FCT) through project UIDB/04326/2020.

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

The aquaculture sector has experienced rapid and important growth with the subsequent increase of feeding and nutritional issues for sustaining this activity, mainly related to the use of high quality, safe and environmentally friendly feed ingredients. The use of additives in aquafeeds has proven to be a suitable option to improve different productive indicators in farmed fish. In the present study, the effect of adding the GHRP-6 peptide, a ghrelin analog, to a commercial diet of gilthead sea bream (Sparus aurata) was studied at two proportions (100 or 500 µg/kg of feed). Both experimental diets show an increase in growth performance, as well as in feed efficiency after 97 days of experiment. The lower inclusion of GHRP-6 (100 µg/kg) results in a better aerobic metabolism, while the higher inclusion significantly increased plasma GH levels in agreement with the GH secretagogue effects of ghrelin. Similar growth outcome and differences between GHRP-6 levels in aerobic metabolism and GH stimulation suggest that improvements in culture performance by this peptide may occur through different mechanisms. Taken together, this compound can be considered as a viable dietary supplement for increasing production efficiency of sea bream aquaculture, although a better understanding of its dose-specific effects is still required. ; This research was supported under the Fellowship for short stays to prestigious researchers awarded by the University of Cadiz (reference EST2019-021) to L.R.-V. Additional funding was obtained by the projects AGL2016-76069-C2-1-R of MICINN (Spain) to J.M.M, and co-financed by the European Union under the 2014–2020 ERDF Operational Programme and by the Department of Economic Transformation, Industry, Knowledge, and Universities of the Regional Government of Andalusia (Project reference: FEDER-UCA18-107182) to J.A.M.-S. J.M.M. and J.A.M.-S. belong to the Fish Welfare and Stress Network (AGL2016-81808-REDT) supported by the Spanish Ministry of Economy, Industry and Competitiveness. ; Peer reviewed

Osmotic costs in teleosts are highly variable, reaching up to 50% of energy expenditure in some. In several species, environmental salinities close to the isosmotic point (~15 psu) minimize energy demand for osmoregulation while enhancing growth. The present study aimed to characterize the physiological status related to osmoregulation in early juveniles of the greater amberjack, Seriola dumerili, acclimated to three salinities (15, 22, and 36 psu). Our results indicate that plasma metabolic substrates were enhanced at the lower salinities, whereas hepatic carbohydrate and energetic lipid substrates decreased. Moreover, osmoregulatory parameters, such as osmolality, muscle water content, gill and intestine Na-K-ATPase activities, suggested a great osmoregulatory capacity in this species. Remarkably, electrophysiological parameters, such as short-circuit current (Isc) and transepithelial electric resistance (TER), were enhanced significantly at the posterior intestine. Concomitantly, Isc and TER anterior-to-posterior intestine differences were intensified with increasing environmental salinity. Furthermore, the expression of several adeno-hypophyseal genes was assessed. Expression of prl showed an inverse linear relationship with increasing environmental salinity, while gh mRNA enhanced significantly in the 22 psu-acclimated groups. Overall, these results could explain the better growth observed in S. dumerili juveniles kept at salinities close to isosmotic rather than in seawater. ; This research was funded by Project "Diversificación de la Acuicultura Española mediante la optimización del cultivo de Seriola dumerili" JACUMAR 2016 (MAPAMA) and Fondo Europeo Marítimo y de Pesca (FEMP). The authors (A.B. and J.M.M.) belong to the FishWelfare and Stress Network (AGL2016-81808-REDT), supported by the Agencia Estatal de Investigación (MINECO, Spanish Government).

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