Muscle Of Sea Bream Research Articles

Mitochondrial activity as an indicator of fish freshness

The current methods used to routinely assess freshness in the fishing industry reflect more a state of spoilage than a state of freshness. Mitochondria, the seat of cellular respiration, undergo profound changes in post mortem tissues. The objective of this study was to demonstrate that mitochondrial activity constitutes a putative early fish freshness marker. The structure of gilthead sea bream (Sparus aurata) muscle tissue was evaluated over time by transmission electron microscopy. Respiration was assessed in mitochondria isolated from sea bream fillets using oxygraphy. Membrane potential (ΔΨm) was determined by fluorescence (Rhodamine 123). Mitochondrial activity of fillets stored at +4 °C was studied for 6 days. Changes in mitochondrial cristae structure appeared from Day 3 highlighting the presence of dense granules. ΔΨm and mitochondrial activity were significantly disrupted in sea bream fillets after 96 h of storage at +4 °C. Mitochondrial activity constituted a reliable and early indicator of fish freshness.

Somatotropic Axis Regulation Unravels the Differential Effects of Nutritional and Environmental Factors in Growth Performance of Marine Farmed Fishes.

The Gh/Prl/Sl family has evolved differentially through evolution, resulting in varying relationships between the somatotropic axis and growth rates within and across fish species. This is due to a wide range of endogenous and exogenous factors that make this association variable throughout season and life cycle, and the present minireview aims to better define the nutritional and environmental regulation of the endocrine growth cascade over precisely defined groups of fishes, focusing on Mediterranean farmed fishes. As a result, circulating Gh and Igf-i are revitalized as reliable growth markers, with a close association with growth rates of gilthead sea bream juveniles with deficiency signs in both macro- or micro-nutrients. This, together with other regulated responses, promotes the use of Gh and Igf-i as key performance indicators of growth, aerobic scope, and nutritional condition in gilthead sea bream. Moreover, the sirtuin-energy sensors might modulate the growth-promoting action of somatotropic axis. In this scenario, transcripts of igf-i and gh receptors mirror changes in plasma Gh and Igf-i levels, with the ghr-i/ghr-ii expression ratio mostly unaltered over season. However, this ratio is nutritionally regulated, and enriched plant-based diets or diets with specific nutrient deficiencies downregulate hepatic ghr-i, decreasing the ghr-i/ghr-ii ratio. The same trend, due to a ghr-ii increase, is found in skeletal muscle, whereas impaired growth during overwintering is related to increase in the ghr-i/ghr-ii and igf-ii/igf-i ratios in liver and skeletal muscle, respectively. Overall, expression of insulin receptors and igf receptors is less regulated, though the expression quotient is especially high in the liver and muscle of sea bream. Nutritional and environmental regulation of the full Igf binding protein 1–6 repertoire remains to be understood. However, tissue-specific expression profiling highlights an enhanced and nutritionally regulated expression of the igfbp-1/-2/-4 clade in liver, whereas the igfbp-3/-5/-6 clade is overexpressed and regulated in skeletal muscle. The somatotropic axis is, therefore, highly informative of a wide-range of growth-disturbing and stressful stimuli, and multivariate analysis supports its use as a reliable toolset for the assessment of growth potentiality and nutrient deficiencies and requirements, especially in combination with selected panels of other nutritionally regulated metabolic biomarkers.

Long-term stability of RNA isolated from muscle of red seabream (Pagrus major) during ice storage.

Recovering high-quality intact RNA from postmortem tissue is of major concern for gene expression studies. However, it is difficult to perform RNA extraction from aquacultured fish immediately after death, as rapid and accurate skills are needed for the procedure. The objective of this study was to quantitatively assess the integrity of total RNA extracted from muscle, liver, and digestive tract tissues of red seabream stored in ice as whole bodies, at a range of time points up to 10days postmortem, using RNA integrity number (RIN) and quantitative PCR (qPCR). The RIN of total RNA in muscle remained over 8.0 for 5days postmortem. The RINs in the liver and digestive tract were under 5.0 at 2days postmortem. The mRNA levels of tissue inhibitor metalloproteinase 2 (TIMP-2) and β-actin, measured using qPCR in muscle, decreased to 87.8% at 1day postmortem and to 45.5% at 2days postmortem, from that at 0days postmortem. In the liver and digestive tract, the mRNA levels were not significantly changed until 1day postmortem. These results indicate that RNA, especially from fish muscle, can be maintained at high quality for several days postmortem solely by storing the fish body in ice.

Effects of olive leaf powder supplemented to fish feed on muscle protein of red sea bream.

Olive leaf is known to have the high polyphenol content of 6-9% in dry weight. We investigated the effects of olive leaf powder (OLP) supplemented to fish feed on muscle protein of red sea bream (Pagrus major). Fish reared with feed containing 8% OLP for 40days had 1.4 times higher myofibril content and 2.2 times higher acid-soluble collagen content than fish reared with control feed for the same period. On the other hand, sarcoplasmic protein content and collagenase activity of the muscle were almost the same between the control fish and OLP-diet fish. Microstructure observation of fish muscle showed that OLP-diet fish has more rigid endomysium structure than that of the control-diet fish. Since collagen fiber in endomysium is responsible for the texture of the muscle, feeding OLP to aquaculture fish will lead to a harder muscle texture. The present study suggests that OLP is a useful feed additive to enhance the texture of aquaculture red sea bream muscle through strengthening of the collagen structure in the muscle.

Spectroscopic analyses and genotoxicity of dioxins in the aquatic environment of Alexandria

Dioxins have global concerns because of the bioaccumulation tendency and persistency in the environment. Water, seabream Pagrus auratus and seabass Dicentrarchus labrax samples were collected from Abu Qir, Alexandria to evaluate the concentration of dioxin. Fourier Transform Infrared Spectrometer (FTIR) and molecular modeling was applied for elucidating the molecular structure of fish samples. Furthermore, HPLC with UV detection was used to determine the concentration of dioxins (2,8-dichloro dibenzo-p-dioxin). RT-PCR assay was conducted to verify the expression of some immune genes in the fish species as a result of water pollution. The average detected concentrations varied from 0.2 to 1.3μg/l. Gene expression revealed that MHC class 1 and C3 were highly upregulated in liver and muscle of seabass and seabream while T2BP was highly regulated in seabass liver and seabream muscle and seabass muscle for transferrin, FTIR and molecular modeling indicate that dioxin finds its way to fish protein.

Pharmacokinetics of chloramphenicol (CAP) in gilthead sea bream (Sparus aurata) and its in vitro activities against important bacterial fish pathogens

The pharmacokinetics of chloramphenicol (CAP) in gilthead sea bream (Sparus aurata), a warm water farmed fish species and its in vitro efficacy against important bacterial diseases of Mediterranean mariculture were investigated in this study. After an intravascular injection (10 mg/kg/fish), the distribution half-life (tl/2a) and the elimination half-life (tl/2ß) of CAP were calculated to be 1.6 and 69 h, respectively. Tissue penetration of CAP was found to be moderate since both the apparent volume of distribution of the drug at steady-state (V<i(ss)) and the apparent volume of the central compartment (Vc) were calculated to be 1.13 and 0.90 L/kg. The total clearance (CLp) of the drug was slow (0.022 L/kg/h). The minimum inhibitory concentration (MIC) values of CAP in distilled water supplemented with 2% NaCl against Vibrio anguillarum serotype lb, Photobacterium damsela subsp. piscicida, V alginolyticus and V ßuvialis were determined to be 4.78 pg/mL, while it was 0.60 pg/mL for V. damsela. The addition of 10 mM Ca2+ and 55 mM Mg2+ in the medium revealed MIC values of 19.13 pg/mL for V alginolyticus and V ßuvialis, whereas showed no effect for V anguillarum P. damsela subsp. Piscicida and V damsela. The results indicate that CAP displayed a satisfactory kinetic profile and it is eliminated fast from gilthead sea bream muscle; however, its high MIC values stress show a possible inefficacy against important bacterial pathogens of Mediterranean mariculture.

Evaluation of antimicrobials residues in farmed gilthead seabream (Sparus aurata) after administration through medicated feed

The use of antimicrobials in aquaculture is a well-known fact and merits the focus of the scientific community. In the present study, five drugs (oxytetracycline, sulfadiazine, trimethoprim, oxolinic acid and flumequine) were selected to assess their retention in muscle tissues from gilthead seabream (Sparus aurata). Fish were placed in 150 L tanks at 18 °C, and fed for 7 days with experimental diets containing two concentrations of each antimicrobial (ranging from 5.51 to 131.16 mg kg−1). Edible tissues were then analyzed through a validated multi-class quantification method (UHPLC-MS/MS). The results indicate that sulfadiazine concentrations were the highest immediately after the feeding period and decreased towards day 3. Flumequine was only detected on the first day with concentrations below the MRL. Both trimethoprim and oxolinic acid concentrations were below the MRLs 3 days after the feeding period was over (oxolinic acid was not detected in muscle samples at day 14 for prophylaxis and day 28 for both treatments). Oxytetracycline residues in muscle tissues were the highest through time, with concentrations above the MRL for 7 days (Cday7 of 111.2 and 157.2 μg kg−1 for both dosages). Results suggest that these antimicrobials can be present in gilthead seabream muscle samples for longer periods than previously reported, when realistic conditions are tested. With the exception of oxytetracycline, concentrations were below the MRLs established 3 days after the feeding trial was over meaning that adverse effects related to human consumption are not likely. Nevertheless, allergic reactions or resistance to antimicrobials can be developed if low concentrations of such compounds are ingested on a frequent basis, as is the case of the Mediterranean diet.

Proteolytic degradation of myofibrillar components by endogenous proteases in red sea bream muscle

Proteolytic degradation of myofibrillar components by endogenous proteases in red sea bream muscle

Influence of waterborne arsenic on nutritive and potentially harmful elements in gilthead seabream (Sparus aurata).

Fish are an important source of nutrients in human nutrition. Although arsenic (As) is considered potentially carcinogenic for human being, very little is known about its toxicity in fish biology. To increase our knowledge of the effect of exposure to waterborne As on fish, gilthead seabream (Sparus aurata) were exposed to 5μM As2O3 and the bioaccumulation of macronutrients (Ca, K, Mg, Na, P), micronutrients (Fe, Mn, Zn) and Potentially Harmful Elements (As, Cd) was determined using spectrometric techniques. All elements were determined in the muscle and liver of non-exposed fish and those exposed to As for 2, 10 or 30days. The concentrations of K, Na, Mg, Mn and Zn (in muscle) and Fe and Mn (in liver) of control (non-exposed) fish were higher than those determined in exposed fish. Furthermore, neither As nor Cd accumulated in the edible part (muscle) of seabream and were only evident in liver after 30days of continuous exposure to As, but both concentrations remained below legally established limits.

Characterization and in vitro sensitivity of cholinesterases of gilthead seabream (Sparus aurata) to organophosphate pesticides.

The characterization of cholinesteraseactivity in brain and muscle of gilthead seabream was carried out using four specific substrates and three selective inhibitors. In addition, K m and V max were calculated from the Michaelis-Menten equation for ASCh and BSCh substrates. Finally, the in vitro sensitivity of brain and muscle cholinesterases to three organophosphates (OPs) was also investigated by estimating inhibition kinetics. The results indicate that AChE is the enzyme present in the brain, whereas in muscle, a typical AChE form is present alongwith an atypical form of BChE. Very low ChE activity was found in plasma with all substrates used. The inhibitory potency of the studied OPs on brain and muscle AChEs based on bimolecular inhibition constants (k i ) was: omethoate<dichlorvos<azinphosmethyl-oxon. Furthermore, muscle BChE was found to be several orders of magnitude (from 2 to 4) more sensitive than brain and muscle AChE inhibition by dichlorvos and omethoate.

Role of mariculture in the loading and speciation of mercury at the coast of the East China Sea

The effects of mariculture on mercury (Hg) contamination and speciation in water, sediment and cultured fish in a typical mariculture zone located in Xiangshan bay, Zhejiang province, east China, were studied. Water, sediment and fish samples were collected from mariculture sites (MS) and from corresponding reference sites (RS) 2500 m away from the MS. The THg concentration in overlying water in Xiangshan bay reached as high as 16.6 ± 19.5 ng L−1, indicating that anthropogenic sources in this bay may contribution on Hg contamination in overlying water. Mariculture activities resulted in an increase in THg concentration in water from surface and bottom layers, which may be attributed to the discharge of domestic sewage and the accumulation of unconsumed fish feed and fish excreta in the benthic environment. Methylmercury (MeHg) concentrations in the bottom layer of overlying water and top surface layer of porewater underneath MS were higher than at RS, implying that mariculture activities promote Hg methylation in the interface between sediments and water. In addition, the concentrations of MeHg in sediment and porewater were significantly higher in summer than winter. It was observed that THg and MeHg contents in the muscle of blackhead seabream (Acanthopagrus schlegelii) (fed by the trash fish) were significantly higher (p < 0.001) than those in red snapper (Lutjanus campechanus) or perch (Perca fluviatilis) (fed by pellet fish feed). The THg and MeHg concentrations in the fish meat were closely related to the feeding mode, which indicate that fish feed rather than environmental media is the major pathway for Hg accumulation in fish muscle.

Comparative contribution of trophic transfer and biotransformation on arsenobetaine bioaccumulation in two marine fish

Marine fish can accumulate high arsenic (As) concentrations, with arsenobetaine (AsB) as the major species in the body. However, whether the high AsB accumulation in fish occurs mainly through trophic transfer from diet or biotransformation in the fish body remains unclear. This study investigated the trophic transfer and biotransformation of As in two marine fish (seabream Acanthopagrus schlegeli and grunt Terapon jarbua) fed artificial and clam diets for 28 d. The different diets contained different proportions of inorganic [As(III) and As(V)] and organic [methylarsenate (MMA), dimethylarsenate (DMA), and AsB] As compounds. Positive correlations were observed between the accumulated As concentrations and AsB concentrations in both fish, suggesting that AsB contributed to the accumulation of total As in marine fish. Based on the calculated total input of AsB and detected AsB concentrations in the muscle of the seabream and grunt, the ingested amounts of AsB accounted for 0.1–0.3%, 8.1–14.4% of detected AsB concentrations, respectively, in the muscle of seabream and grunt fish species, suggesting that AsB was mainly biotransformed versus trophically transferred in these marine fish. In summary, this study demonstrates that marine fish prefer to biotransform inorganic As forms into AsB, resulting in high bioaccumulation of total As.

NADPH production, a growth marker, is stimulated by maslinic acid in gilthead sea bream by increased NADP-IDH and ME expression

NADPH plays a central role in reductive biosynthesis of membrane lipids, maintenance of cell integrity, protein synthesis and redox balance maintenance. Hence, NADPH is involved in the growth and proliferation processes. In addition, it has been shown that changes in nutritional conditions produced changes in NADPH levels and growth rate. Maslinic acid (MA), a pentacyclic triterpene of natural origin, is able to stimulate NADPH production, through regulation of the two oxidative phase dehydrogenases of the pentose phosphate pathway. Our main objective was to study the effects of MA on the kinetic behaviour and on the molecular expression of two NADPH-generating systems, NADP-dependent isocitrate dehydrogenase (NADP-IDH) and malic enzyme (ME), in the liver and white muscle of gilthead sea bream (Sparus aurata). Four groups of 12g of a mean body mass were fed for 210days in a fish farm, with diets containing 0 (control), and 0.1g of MA per kg of diet. Two groups were fed ad libitum (C-AL and MA-AL) and another's two, with restricted diet of 1% of fish weight (C-R and MA-R). Results showed that MA significantly increased the main kinetic parameter of the NADPH-forming enzymes (NADP-IDH and ME). In this sense, specific activity, maximum velocity, catalytic efficiency and activity ratio values were higher in MA conditions than control groups. Moreover, these changes were observed in both feeding regimen, AL and R. Meanwhile, the Michaelis constant changed mainly in groups fed with the MA and restricted diet, these changes are related to the best substrate affinity by enzyme. Moreover, in the Western-blot result, we found that MA increased both protein levels studied, this behaviour being consistent with the regulation of the number of enzyme molecules. All results, indicate that MA, independently of the fed regimen, could potentially be a nutritional additive for fish as it improved the metabolic state of fish, as consequence of increased activity and expression of NADP-IDH and ME enzymes.

Determination of sulfadiazine, trimethoprim, and N(4) -acetyl-sulfadiazine in fish muscle plus skin by Liquid Chromatography-Mass Spectrometry. Withdrawal-time calculation after in-feed administration in gilthead sea bream (Sparus aurata L.) fed two different diets.

This study presents a depletion study for sulfadiazine and trimethoprim in muscle plus skin of gilthead sea bream (Sparus aurata L.). N(4) -acetyl-sulfadiazine, the main metabolite of sulfadiazine (SDZ), was also examined. The fish were held in seawater at a temperature of 24-26°C. SDZ and trimethoprim (TMP) were administered orally with medicated feed for five consecutive days at daily doses of 25mg SDZ and 5mg TMP per kg of fish body weight per day. Two different diets, fish oil- and plant oil-based diets, were investigated. Ten fish were sampled at each of the days 1, 3, 5, 6, 8, 9, 10, and 12 after the start of veterinary medicine administration. However for the calculation of the withdrawal periods, sampling day 1 was set as 24 h after the last dose of the treatment. Fish samples were analyzed for SDZ, TMP, and acetyl-sulfadiazine (AcSDZ) residues by liquid chromatography-mass spectrometry. SDZ and TMP concentrations declined rapidly from muscle plus skin. Considering a maximum residue limit of 100μg/kg for the total of sulfonamides and 50μg/kg for TMP residues in fish muscle plus skin, the withdrawal periods of the premix trimethoprim-sulfadiazine 50% were calculated as 5 and 6days, at 24-26 °C, in fish oil (FO) and plant oil (PO) groups, respectively. The investigation of this work is important to protect consumers by controlling the undesirable residues in fish.

Exposure of sea bream (Sparus aurata) to toxic concentrations of benzo[a]pyrene: possible human health effect

Polycyclic aromatic hydrocarbons (PAHs) can accumulate in the food chain, due to their lipophilic properties. Fish can accumulate contaminants including PAHs and frequent consumption of such contaminated fish can pose risk to human health. The aim of this study was to clarify if acute exposure of sea bream (Sparus aurata, a fish species of great economic importance in the Atlantic and Mediterranean areas) to a PAH, benzo[a]pyrene (B[a]P), at a dose that can induce CYP1A and pathological changes in fish gills, liver and muscle, can induce accumulation in muscle. We investigated the cytotoxic effects (as changes in cell viability, DNA laddering and glutathione content) of in vitro exposure of human peripheral blood mononuclear cells (PBMCs) to organic extracts obtained from muscle of sea breams previously exposed via water to B[a]P (2mg/l, for 12, 24 and 72h). At this level of exposure, B[a]P caused morphological changes, inflammatory response and CYP1A induction not only in sea bream gills and liver but also in muscle; furthermore, in fish muscle we observed a substantial B[a]P accumulation, which may be associated with the increased CYP1A activity in liver and especially in muscle. However, when PBMCs were exposed to organic extracts obtained from sea bream muscle contaminated with B[a]P, a toxic, although modest effect was revealed, consisting in a significant decrease in cell glutathione levels without alterations in cell viability and DNA laddering. This suggests that consumption of sea breams from B[a]P contaminated waters might represent a risk for human health.

CLA 첨가사료가 감성돔(Acanthopagrus schlegeli) 성장과 지방산 조성 및 내장 추출지방이 지방세포 3T3-L1에 미치는 영향

Three groups of black seabream (Acanthopagrus schlegeli) were fed with treatment diets containing certain concentrations of conjugated linoleic acid (CLA) and carotenoids. The control group feed contained 0% CLA and 0% carotenoids, the CP10 group feed contained 1% CLA and 0.1% carotenoids, and the CP25 group feed contained 2.5% CLA and 0.1% carotenoids . The CP10 and CP25 groups demonstrated the enhanced growth and increased feed conversion efficiency of black seabream. The specific growth rates (SGRs) were 0.74, 0.81, and 0.97, while the feed conversion ratios (FCRs) were 2.65, 2.46, and 2.04 for the control, CP10, and CP25 groups, respectively. The total contents of high unsaturated fatty acid (HUFA) for the control, CP10, and CP25 groups were 41.0%, 41.7%, and 43.5%, respectively. CLA was deposited to the extent of 2.8% and 5.6% in the muscle, and 4.0% and 8.3% in the viscera of the CP10 and CP25 groups, respectively. Meanwhile, treatment with the viscera lipid extract (VLE) from CP25 fish evidently lowered 3T3-L1 adipocytes viability. The lipid extract from the muscle and viscera of black seabream contained ample amounts of beneficial substances, such as CLA, carotenoids, EPA, and DHA. CLA, which enriched black seabream m uscle, could be categorized as a functional food and serve as a well-being food. Meanwhile, th e fish oil from its viscera could serve as a high function supplement.

ROLES OF APOPTOSIS AND AUTOPHAGY ON THE TEXTURE OF RED SEA BREAM MUSCLE

One of commercial brands in farmed-products of red sea bream (Pagrus major), named “Date-Madai”, is known to possess hard texture and transparency when served as “Sashimi”. The quality of “Sashimi” is usually evaluated by texture, appearance, and color of dark muscle. These characters easily change worse during post mortem storage. The aim of this study was to reveal relationship between proteolytic degradation and muscle quality of the red sea bream. Sensory analysis was carried out to evaluate the quality of “Sashimi” in terms of texture and appearance of flesh. Western blot analysis was conducted to evaluate protein expressions of red sea bream muscle. Significantly higher score in the sensory analysis for brightness was given to the “Date-Madai”. Similar tendency were also observed in color, texture and general acceptability. Intracellular effector of the apoptotic pathway includes contributin of caspase family. Lower level in caspase-3 protein was observed in the “Date-Madai” muscle. Autophagy is known to be inhibited by the target of rapamycin (TOR) signaling. Phosphorylated ribosomal protein S6 kinase, which is in the downstream of the TOR, increased in the “Date- Madai” muscle. This study concluded that the apoptosis and autophagy could be associated with the quality of the red sea bream. Keywords: apoptosis, autophagy, proteases, red sea bream

Dietary macroalgae is a natural and effective tool to fortify gilthead seabream fillets with iodine: Effects on growth, sensory quality and nutritional value

Marine fish are a rich source of iodine in the human diet. Exogenous feeding under captivity opens the possibility of tailoring fish composition with health valuable nutrients, such as iodine, and establishing it as a functional food. A study was undertaken to test the efficacy of various dietary iodine supplemental forms on the growth performance of gilthead seabream and assess the effects on sensory attributes and nutritional value of fillets. Duplicate groups of 35 seabream (IBW: 252 g) were fed over 118 days: a) control diet (CTRL) with 3 mg I kg− 1, supplied as potassium iodide; b) this same control diet supplemented with potassium iodide (diet KI: 26 mg I·kg− 1) or with ethylenediamine dihydroiodide (diet EDDI; 22 mg I·kg− 1); c) a fourth diet with 10% of Laminaria digitata, an iodine-rich macroalgae (diet LAM). At the end of the trial, fish doubled their initial weight, but irrespective of the iodine form used, the elevation of dietary iodine level had no effect (P > 0.05) on feed intake, growth rate, feed conversion, nutrient utilization or whole-body composition. Dietary iodine supplementation led to a significant increase (P < 0.05) of the iodine content in seabream fillets. In comparison to the CTRL treatment (0.13 mg·kg− 1), seabream fed KI and EDDI supplemented diets showed a significant enhancement (P < 0.05) of their fillet iodine content (0.17 mg·kg− 1). Feeding seabream with the iodine-rich brown algae L. digitata resulted in a significant (P < 0.05) 6.5-fold increase (0.84 mg·kg− 1 fillet) of fillet iodine content over the levels found in the CTRL treatment. Overall sensory difference between CTRL and fish fed supplemented diets was significant (P < 0.05) only for fish fed the EDDI diet. Steam-cooking elicited 13–20% losses of the iodine content of seabream fillets. Iodine supplementation had no effect (P > 0.05) on the fatty acid profile of seabream muscle. Dietary iodine-rich macroalgae was an effective and natural strategy to fortify muscle with iodine, showing that a 160 g portion of steam-cooked seabream fillets could cover approximately 80% of the Daily Recommended Intake for iodine and 370% of the Daily Adequate Intake of EPA + DHA for enhanced cardiovascular health in adults.

Multi-residue and multi-class determination of antibiotics in gilthead sea bream (Sparus aurata) by ultra high-performance liquid chromatography-tandem mass spectrometry

This paper describes a method for the determination of 41 antibiotics from seven different classes in gilthead sea bream (Sparus aurata) by ultra-high-performance liquid chromatography with tandem mass spectrometry (UPLC-MS/MS). Sulfonamides, trimethoprim, tetracyclines, macrolides, quinolones, penicillins and chloramphenicol were simultaneously determined. Fourteen procedures for sample treatment were tested and an extraction with acetonitrile and ethylenediaminetetra acetic acid was found to be the best option. The methodology was validated in accordance with Decision 2002/657/EC. Precision in terms of relative standard deviation (RSD) was under 17% for all compounds, and the recoveries ranged from 92% to 111%. CCα and CCβ were determined according to the maximum residue limit or the minimum required performance limit, when necessary. The validation provided evidence that the method was suitable for application in routine analysis for the detection and confirmation of antibiotics in muscle of gilthead sea bream, an important and intensively produced fish in aquaculture.

Plant protein and vegetable oil-based diets modulate gilthead seabream (Sparus aurata) muscle biochemical status and proteolytic enzymes at an early postmortem stage

A 70 days feeding trial was carried out on juvenile gilthead seabream (Sparus aurata) (mean initial body weight: 362 ± 59 g) to evaluate whether the simultaneous replacement of fishmeal and fish oil by vegetable ingredients affected the muscle's proteolytic potential. Fish were fed either a fishmeal/fish oil diet, a fishmeal/vegetable oil diet, a plant protein/fish oil or a plant protein/vegetable oil diet. The use of dietary plant proteins resulted in lower sulphated glycosaminoglycans' content and lower glycogen phosphorylase activity in the muscle, while both plant proteins and vegetable oil increased muscle pH and reduced cathepsin B activity. Our results indicate that high replacement of fish meal and/or fish oil with plant ingredients has a significant impact on early postmortem metabolic processes and proteolytic potential of seabream muscle, especially when replacing both fish meal and fish oil.