Browsing by Author "Vargas-Chacoff, L."
Now showing 1 - 7 of 7
Results Per Page
Sort Options
- Changes in plasma amino acid levels in a euryhaline fish exposed to different environmental salinitiesPublication . Aragão, C.; Costas, B.; Vargas-Chacoff, L.; Ruiz-Jarabo, I.; Dinis, Maria Teresa; Mancera, J. M.; Conceição, L. E. C.Previous studies have shown that Senegalese sole is partially euryhaline in the juvenile phase, being able to adapt to a wide range of salinities in a short-time period, due to changes at the osmoregulatory and metabolic level. This study aimed to assess the effects of acclimation of sole to a wide range of salinities, with a special emphasis on the role of plasma amino acids during this process. Sole juveniles were acclimated for 2 weeks to different salinities: 5, 15, 25, 38, and 55 g L−1. Plasma levels of cortisol, glucose, osmolality, and free amino acids were assessed at the end. Changes in plasma levels of cortisol, glucose, and amino acids indicate that fish reared at 5 and 55 g L−1 were facing extra energy costs. Amino acids seem to play an important role during salinity acclimation, either as energy sources or as important osmolytes for cell volume regulation.
- Characterization of the peripheral thyroid system of gilthead seabream acclimated to different ambient salinitiesPublication . Ruiz-Jarabo, I.; Klaren, P. H. M.; Louro, Bruno; Martos-Sitcha, J. A.; Pinto, P. I.; Vargas-Chacoff, L.; Flik, G.; Martinez-Rodriguez, G.; Power, Deborah; Mancera, J. M.; Arjona, F. J.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, ff4), 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 ff4 (184%) plasma concentrations compared to control animals (acclimated to 40 ppt, natural salinity conditions in the Bay of Cadiz, Spain), while the amount of pituitary thyroid stimulating hormone subunit 13 (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 (diol 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. (C) 2016 Elsevier Inc. All rights reserved.
- Different environmental temperatures affect amino acid metabolism in the eurytherm teleost Senegalese sole (Solea senegalensis Kaup, 1858) as indicated by changes in plasma metabolitesPublication . Costas, B.; Aragão, C.; Ruiz-Jarabo, I.; Vargas-Chacoff, L.; Arjona, F. J.; Mancera, J. M.; Dinis, Maria Teresa; Conceição, L. E. C.Senegalese sole (Solea senegalensis) is a eurytherm teleost that under natural conditions can be exposed to annual water temperature fluctuations between 12 and 26C. This study assessed the effects of temperature on sole metabolic status, in particular in what concerns plasma free amino acid changes during thermal acclimation.
- Feed deprivation in Senegalese sole (Solea senegalensis Kaup, 1858) juveniles: Effects on blood plasma metabolites and free amino acid levelsPublication . Costas, B.; Aragão, C.; Ruiz-Jarabo, I.; Vargas-Chacoff, L.; Arjona, F. J.; Dinis, Maria Teresa; Mancera, J. M.; Conceição, L. E. C.The effects of prolonged feed deprivation were assessed on blood plasma metabolites and free amino acid levels in Solea senegalensis. Juvenile specimens were maintained at two experimental conditions (24 h fasted and 21 days feed-deprived). In feed-deprived fish, relative growth rate and hepatosomatic index as well as plasma triglycerides and proteins levels were significantly lower.
- Francisella noatunensis modulates the hepatic profile of fatty acids in Patagonian blennie Eleginops maclovinusPublication . Oyarzún-Salazar, R.; Lagos, Carolina; Orellana, P.; Dantagnan, P.; Muñoz, J.L.P.; Romero, A.; Vargas-Chacoff, L.Fatty acids (FA) have been reported to play a role in the defense against bacterial pathogens. However, studies in fish are limited and no information exists on the modulation of FA of Eleginops maclovinus challenged with the pathogen of aquaculture relevance Francisella noatunensis. We inoculated 144 fish intraperitoneally with 3 doses (low dose [LD]: 1 x 101 bact/mu L; medium dose [MD]: 1 x 105 bact/mu L; high dose [HD]: 1 x 1010 bact/mu L) and a control dose (sterile culture medium, [C]) of the bacteria F. noatunensis and took liver samples at 1, 3, 7, 14, 21, 28 days post-inoculation (dpi). The LD of F. noatunensis did not present significant differences to the C, except for the C20:4n6 (ARA) at day 28, while the MD and HD of F. noatunensis did generate a significant effect of the FA profile of E. maclovinus. We observed a greater modulation after administering the HD of bacteria and detected significant differences from day 3 post-inoculation (P < 0.05). Significantly high levels of C18:0 was detected at day 28 (P < 0.05), while significantly low levels of C14:0, C20:0, C16:1, C18:1n9, C18:2n6; C18:3n3, and C20:5n3 were detected at different dpi of F. noatunensis (P < 0.05). ARA and C22:6n3 (DHA) showed a significant decrease during the first dpi (P < 0.05) but later they showed an increase in their levels, with ARA increasing its levels from day 14 (P < 0.05), while DHA increased its levels only at day 28 (P < 0.05). A large number of FA were highly correlated with each other and multivariate statistical analyzes (PCA and random forest) were able to detect the HD of F. noatunensis as the dose that most affects the FA profile of E. maclovinus, while the LD, MD and C cannot be differentiated in their FA profile. The FA most affected by the challenge with F. noatunensis were C18:2n3 and C18:3n3 (P < 0.05). Our results suggest a relationship between the bioavailability of FA in the liver and the level of the physiological response of E. maclovinus to an experimental challenge with F. noatunensis and suggest that hepatic FA modulation may explain or be part of the high tolerance to bacterial infections reported for E. maclovinus, although more studies are necessary to clarify the roles of the different types of FA on pathogen-host dynamics and its potential use in combating fish pathogenic bacteria.
- Metabolic responses to salinity changes in the subantarctic notothenioid teleost Eleginops maclovinusPublication . Vargas-Chacoff, L.; Moneva, F.; Oyarzun, R.; Martinez, D.; Saavedra, E.; Ruiz-Jarabo, I.; Munoz, J. L. P.; Bertran, C.; Mancera, J. M.Eleginops maclovinus is an endemic, subantarctic Notothenioidei species. This study examined the influence of different environmental salinities (5, 15, and 45 psu; and 32 psu as a control) on energy metabolism in E. maclovinus over a period of 14 days. Metabolite contents and enzymatic activities related to carbohydrate, amino acid, and lipid metabolisms were evaluated in metabolic (liver) and osmoregulatory (gill and kidney) tissues. At extreme salinities (5 and 45 psu), the liver showed a high consumption of energy reserves, mainly as amino acids and carbohydrates. Carbohydrate metabolism in the gills did not change under different salinities, but increased lactate levels were found, suggesting that this tissue may use lactate as an energy substrate. Amino acid metabolism in the gills decreased at 5 psu but increased at 45 psu, and lipid metabolism increased at 5 and 15 psu during the first days of the trial, indicating a possible use of lipids as energy. Kidney carbohydrate catabolism and amino acid metabolism increased after 14 days at 45 psu, while lipid metabolism did not vary in relation to salinity changes. Together, these results suggest that the liver is most affected by salinity changes, probably due to its role as a supplier of energetic substrates. The gills and kidney, osmoregulatory tissues, maintained their energy metabolism levels with minor modifications. In conclusion, E. maclovinus exhibits metabolic adjustments to adapt to different salinities, showing the best responses in isosmotic environmental salinities.
- Physiological short-term response to sudden salinity change in the Senegalese sole (Solea senegalensis)Publication . Herrera, M.; Aragão, C.; Hachero-Cruzado, Ismael; Ruiz-Jarabo, I.; Vargas-Chacoff, L.; Mancera, J. M.; Conceição, L. E. C.The physiological responses of Senegalese sole to a sudden salinity change were investigated. The fish were first acclimated to an initial salinity of 37.5 ppt for 4 h. Then, one group was subjected to increased salinity (55 ppt) while another group was subjected to decreased salinity (5 ppt). The third group (control group) remained at 37.5 ppt. We measured the oxygen consumption rate, osmoregulatory (plasma osmolality, gill and kidney Na+,K+-ATPase activities) and stress (plasma cortisol and metabolites) parameters 0.5 and 3 h after transfer. Oxygen consumption at both salinities was higher than for the control at both sampling times. Gill Na+,K+-ATPase activity was significantly higher for the 55 ppt salinity at 0.5 h. Plasma osmolality decreased in the fish exposed to 5 ppt at the two sampling times but no changes were detected for high salinities. Plasma cortisol levels significantly increased at both salinities, although these values declined in the low-salinity group 3 h after transfer. Plasma glucose at 5 ppt salinity did not vary significantly at 0.5 h but decreased at 3 h, while lactate increased for both treatments at the first sampling time and returned to the control levels at 3 h. Overall, the physiological response of S. senegalensis was immediate and involved a rise in oxygen consumption and plasma cortisol values as well as greater metabolite mobilization at both salinities.