Browsing by Author "Martinez-Rodriguez, G."
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- 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.
- Dietary aflatoxin B1 (AFB1) reduces growth performance, impacting growth axis, metabolism, and tissue integrity in juvenile gilthead sea bream (Sparus aurata)Publication . Barany, A.; Guilloto, M.; Cosano, J.; de Boevre, M.; Oliva, M.; de Saeger, S.; Fuentes, J.; Martinez-Rodriguez, G.; Mancera, J. M.Mycotoxins are an increasing threat to all the related commodities from agriculture. Its occurrence is expected to increase due to climate change. Here, we examined the impacts of dietary toxicity of aflatoxin B1 (AFB1) in gilthead sea bream (Sparus aurata) at levels of 1 or 2 mg AFB1 kg(-1)- fish feed. Inclusion of AFB1 in the diet resulted in 80% inhibition of the total weight gain during the 85-day trial. Carbohydrate and lipid energetic metabolites, both in plasma and liver, were depleted. Moreover, the histopathological analysis revealed several tissue anomalies in the liver, kidney, and spleen. Furthermore, the relative expression of gene transcripts for growth regulation was affected by AFB1. Adenohypophyseal gh and hepatic igf1 were inversely correlated due to AFB1 effects. Relative expression levels of gene transcripts as stress indicators were increased at AFB1 highest doses, such as hypothalamic trh, crh, and crhbp, as well as star in head kidney. Interestingly circulating levels of cortisol were unaffected. Overall, our results showed that aquafeeds with AFB1 impaired growth, alter metabolism, tissue integrity, and transcriptomic responses. However, we did find AFB1 residue neither in the liver nor muscle.
- Ontogeny and diurnal patterns of molecular gene expression and activity of digestive enzymes in developing greater amberjackPublication . Gamberoni, P.; Yufera, M.; de las Heras, V; Siguero, I; Gilannejad, N.; Martinez-Rodriguez, G.; Navarro-Guillén, CarmenThe greater amberjack, Seriola dumerili, is a fast-growing pelagic teleost with great interest for the diversification of farmed marine fish species in the Mediterranean region. Aiming to advance the optimization of feeding during the early stage of this species, this study examines the ontogeny of digestive function using molecular and biochemical approaches. Gene expression of digestive enzyme precursors and the enzymatic activity have been determined during the first 51 days post hatching (dph) and during the diurnal period of 19 dph larvae reared in semi-intensive conditions. The expression of pancreatic proteases precursors (try3, ctra and ctrb1) increased from first-feeding, while gastric chitinase (chia1), gastric protease (pga3) and proton pump (atp4a2) after 10 dph. The expression of pancreatic lipases (cel1, cel2 and cel3) peaked between 6 and 10 dph, phospholipase A2 (pla2g1b) rose only after 25 dph, while a-amylase (amy2a) increased mainly from 20 dph. The trypsin activity was more evident from first-feeding to 25 dph and chymotrypsin activity from this day onwards. Acidic chitinase and pepsin activity appeared, respectively, at 16 and 30. The activity of 7C-like lipase was evident from first-feeding but as 4C-like lipase significantly increased from 15 dph, while amylase peaked from 6 to 22 dph. Aminopeptidase and alkaline phosphatase activities started at 20 dph indicating the functional maturation of brush border of the enterocytes. The daily pattern analysis showed a food anticipatory strategy in the expression of proteases related genes. Lipases activity was more evident during the morning hours, followed by amylase, and by alkaline proteases in the afternoon. Results, also, suggested an alternation in the activity of chymotrypsin and trypsin. These ontogenetic patterns are concordant with a carnivorous marine teleost.