Utilização de glúten de trigo na alimentação de dourada, Sparus aurata (Linnaeus, 1758)

A incorporação de fontes proteicas alternativas à farinha de peixe na alimentação de espécies piscícolas tem sido objecto de variados estudos no âmbito da nutrição animal. Neste contexto realizou-se o presente trabalho, cujo objectivo foi determinar o nível de substituição ideal de farinha de peixe por glúten de trigo na alimentação de dourada. Foram realizados dois ensaios, um de crescimento e um de digestibilidade. O ensaio de crescimento efectuou-se para determinar qual o nível máximo de substituição sem que os animais apresentassem diferenças significativas em termos de taxa de crescimento. O ensaio de digestibilidade teve como principal objectivo determinar qual das dietas testadas proporcionaria melhores valores de utilização digestiva por parte dos animais. Tendo em conta os resultados dos ensaios e as condições experimentais em que se realizaram, verificou-se que a substituição até 40% não afecta significativamente o desempenho zootécnico das douradas. ABSTRACT; The incorporation of alternative protein sources in fish diets has been the aim of many scientific experiments in animal nutrition. ln this study, the main objective was to evaluate the ideal level of wheat gluten incorporation in substitution of fishmeal in diets for gilthead sea bream (Sparus aurata L). To reach this objective, two experiments were carried out, in which growth and digestibility were studied. The aim of the growth experiment was to evaluate the maximum level of fish meal substitution by wheat gluten (20%, 40%, 60% and 80%), without affecting significantly the animals growth rate. The digestibility experiment took place to evaluate which animals presented better food utilization with the tested diets (20%, 40%, 60% and 80%). Observing the results of these two experiments, it was concluded that the substitution until 40% did not affect significantly the performance of the fishes.

Formação e desenvolvimento da bexiga gasosa em larvas de dourada (Sparus aurata Linnaeus 1758)

Tese de dout., Unidade de Ciências e Tecnologias dos Recursos Aquáticos, Univ. do Algarve, 1995

Estudo da doença de inverno em dourada (Sparus aurata L.) de cultivo a sul de Portugal

Dissertação de mest. em Aquacultura, Faculdade de Ciências do Mar e do Ambiente, Univ. do Algarve, 2003

Molecular biology of prolactin and prolactin receptor in a marine teleost: the sea bream(Sparus aurata)

Tese de dout. em Biologia, especialidade de Biologia Molecular, Unidade de Ciências e Tecnologias dos Recursos Aquáticos, Univ. do Algarve

Effect of short chain fructooligosaccharides (scFOS) on immunological status and gut microbiota of gilthead sea bream (Sparus aurata) reared at two temperatures

The effects of dietary short chain fructooligosaccharides (scFOS) incorporation on hematology, fish immune status, gut microbiota composition, digestive enzymes activities, and gut morphology, was evaluated in gilthead sea bream (Sparus aurata) juveniles reared at 18 °C and 25 °C. For that purpose, fish with 32 g were fed diets including 0, 0.1, 0.25 and 0.5% scFOS during 8 weeks. Overall, scFOS had only minor effects on gilthead sea bream immune status. Lymphocytes decreased in fish fed the 0.1% scFOS diet. Fish fed the 0.5% scFOS diet presented increased nitric oxide (NO) production, while total immunoglobulins (Ig) dropped in those fish, but only in the ones reared at 25 °C. Red blood cells, hemoglobin, bactericidal activity and NO were higher at 25 °C, whereas total white blood cells, circulating thrombocytes, monocytes and neutrophils were higher at 18 °C. In fish fed scFOS, lymphocytes were higher at 18 °C. Total Ig were also higher at 18 °C but only in fish fed 0.1% and 0.5% scFOS diets. No differences in gut bacterial profiles were detected by PCR-DGGE (polymerase chain reaction denaturing gradient gel electrophoresis) between dietary treatments. However, group's similarity was higher at 25 °C. Digestive enzymes activities were higher at 25 °C but were unaffected by prebiotics incorporation. Gut morphology was also unaffected by dietary prebiotic incorporation. Overall, gut microbiota composition, digestive enzymes activities and immunity parameters were affected by rearing temperature whereas dietary scFOS incorporation had only minor effects on these parameters. In conclusion, at the tested levels scFOS does not seem worthy of including it in gilthead sea bream juveniles diets.

Caracterització estructural i funcional del gen de la miogenia en l’orada (Sparus aurata )

Report for the scientific sojourn at the University of Maryland Biotechnology Institute from February to August 2007. Myogenesis of skeletal muscles in vertebrates is controlled by extracellular signalling molecules together with intracellular transcription factors. Among the transcriptional factors, the members of the myogenic regulatory family play important roles regulating skeletal muscle development and growth. To characterize the gene structure and expression of fish myogenin, we have isolated the myogenin genomic gene and cDNA from gilthead seabream (Sparus aurata) and analyzed the genomic structure, pattern of expression and the regulation of musclespecific expression. Sequence analysis revealed that the seabream myogenin shares a similar gene structure with other fish myogenins, with three exons, two introns and the highly conserved bHLH domain. Expression studies demonstrated that myogenin is expressed in both slow and fast muscles as well as in muscle cells in primary culture. In situ hybridization showed that myogenin was specifically expressed in developing somites of seabream embryos. Promoter activity analysis demonstrated that the myogenin promoter could drive green fluorescence protein expression in muscle cells of zebrafish embryos, as well as in myofibers of adult zebrafish and juvenile seabream.

Metabolic effects of insulin and IGFs on gilthead sea bream (Sparus aurata) muscle cells.

Primary cultures of gilthead sea bream myocytes were performed in order to examine the relative metabolic function of insulin compared with IGF-I and IGF-II (insulin-like growth factors, IGFs) at different stages in the cell culture. In these cells, the in vitro effects of insulin and IGFs on 2-deoxyglucose (2-DG) and L-alanine uptake were studied in both myocytes (day 4) and small myotubes (day 9). 2-DG uptake in gilthead sea bream muscle cells was increased in the presence of insulin and IGFs in a time dependent manner and along with muscle cell differentiation. On the contrary, L-alanine uptake was also stimulated by insulin and IGFs but showed an inverse pattern, being the uptake higher in small myocytes than in large myotubes. The results of preincubation with inhibitors (PD-98059, wortmannin, and cytochalasin B) on 2-DG uptake indicated that insulin and IGFs stimulate glucose uptake through the same mechanisms, and evidenced that mitogenesis activator protein kinase (MAPK) and PI3K-Akt transduction pathways mediate the metabolic function of these peptides. In the same way, we observed that GLUT4 protein synthesis was stimulated in the presence of insulin and IGFs in gilthead sea bream muscle cells in a different manner at days 4 or 9 of the culture. In summary we describe here, for the first time, the effects of insulin and IGFs on 2-DG and L-alanine uptake in primary culture of gilthead sea bream muscle cells. We show that both MAPK and PI3K-Akt transduction pathways are needed in order to control insulin and IGFs actions in these cells. Moreover, changes in glucose uptake can be explained by the action of the GLUT4 transporter, which is stimulated in the presence of insulin and IGFs throughout the cell culture.

Hepatocyte nuclear factor 4alpha transactivates the mitochondrial alanine aminotransferase gene in the kidney of Sparus aurata

Alanine aminotransferase (ALT) plays an important role in amino acid metabolism and gluconeogenesis. The preference of carnivorous fish for protein amino acids instead of carbohydrates as a source of energy lead us to study the transcriptional regulation of the mitochondrial ALT (mALT) gene and to characterize the enzyme kinetics and modulation of mALT expression in the kidney of gilthead sea bream (Sparus aurata) under different nutritional and hormonal conditions. 5′-Deletion analysis of mALT promoter in transiently transfected HEK293 cells, site-directed mutagenesis and electrophoretic mobility shift assays allowed us to identify HNF4α as a new factor involved in the transcriptional regulation of mALT expression. Quantitative RT-PCR assays showed that starvation and the administration of streptozotocin (STZ) decreased HNF4α levels in the kidney of S. aurata, leading to the downregulation of mALT transcription. Analysis of the tissue distribution showed that kidney, liver, and intestine were the tissues with higher mALT and HNF4α expression. Kinetic analysis indicates that mALT enzyme is more efficient in catalyzing the conversion of L-alanine to pyruvate than the reverse reaction. From these results, we conclude that HNF4α transactivates the mALT promoter and that the low levels of mALT expression found in the kidney of starved and STZ-treated fish result from a decreased expression of HNF4α. Our findings suggest that the mALT isoenzyme plays a major role in oxidazing dietary amino acids, and points to ALT as a target for a biotechnological action to spare protein and optimize the use of dietary nutrients for fish culture.

Patterns of primary growth increments in otoliths of Sparus aurata larvae in relation to water temperature and food consumption

Sparus aurata larvae reared under controlled water-temperature conditions during the first 24 days after hatching displayed a linear relationship between age (t) and standard length (SL): SL = 2.68 + 0.19 t (r2 = 0.91l). Increments were laid down in the sagittae with daily periodicity starting on day of hatching. Standard length (SL) and sagittae radius (OR) were correlated: SL(mm) = 2.65 + 0.012 OR(mm). The series of measurements of daily growth increment widths (DWI), food density and water temperature were analyzed by means of time series analysis. The DWI series were strongly autocorrelated, the growth on any one day was dependent upon growth on the previous day. Time series of water temperatures showed, as expected, a random pattern of variation, while food consumed daily was a function of food consumed the two previous days. The DWI series and the food density were correlated positively at lags 1 and 2. The results provided evidence of the importance of food intake upon the sagittae growth when temperature is optimal (20ºC). Sagittae growth was correlated with growth on the previous day, so this should be taken into account when fish growth is derived from sagittae growth rates.

Effect of diet composition and ration size on key enzyme activities of glycolysis-gluconeogenesis, pentose phosphate pathway and amino acid metabolism in liver of Sparus aurata

The effects of diet composition and ration size on the activities of key enzymes involved in intermediary metabolism were studied in the liver of gilthead sea bream (Sparus aurata). Highcarbohydrate, low-protein diets stimulated 6-phosphofructo 1-kinase (EC 2.7.1.11), pyruvate kinase (EC 2.7.1.40), glucose-6-phosphate dehydrogenase (EC 1.1.1.49) and 6-phosphogluconate dehydrogenase (EC 1.1.1.44) enzyme activities, while they decreased alanine aminotransferase (EC 2.6.1.2) activity. A high degree of correlation was found between food ration size and the activity of the enzymes 6-phosphofructo 1-kinase, pyruvate kinase, glucose-6-phosphate dehydrogenase (positive correlations) and fructose-1,6-bisphosphatase (EC 3.1.3.11) (negative correlation). These correlations matched well with the high correlation also found between ration size and growth rate in starved fish refed for 22 d. Limited feeding (5 g/kg body weight) for 22 d decreased the activities of the key enzymes for glycolysis and lipogenesis, and alanine aminotransferase activity. The findings presented here indicate a high level of metabolic adaptation to both diet type and ration size. In particular, adaptation of enzyme activities to the consumption of a diet with a high carbohydrate level suggests that a carnivorous fish like Sparus aurata can tolerate partial replacement of protein by carbohydrate in the commercial diets supplied in culture. The relationship between enzyme activities, ration size and fish growth indicates that the enzymes quickly respond to dietary manipulations of cultured fish.

Effect of diet composition and ration size on key enzyme activities of glycolysis-gluconeogenesis, pentose phosphate pathway and amino acid metabolism in liver of Sparus aurata

The effects of diet composition and ration size on the activities of key enzymes involved in intermediary metabolism were studied in the liver of gilthead sea bream (Sparus aurata). Highcarbohydrate, low-protein diets stimulated 6-phosphofructo 1-kinase (EC 2.7.1.11), pyruvate kinase (EC 2.7.1.40), glucose-6-phosphate dehydrogenase (EC 1.1.1.49) and 6-phosphogluconate dehydrogenase (EC 1.1.1.44) enzyme activities, while they decreased alanine aminotransferase (EC 2.6.1.2) activity. A high degree of correlation was found between food ration size and the activity of the enzymes 6-phosphofructo 1-kinase, pyruvate kinase, glucose-6-phosphate dehydrogenase (positive correlations) and fructose-1,6-bisphosphatase (EC 3.1.3.11) (negative correlation). These correlations matched well with the high correlation also found between ration size and growth rate in starved fish refed for 22 d. Limited feeding (5 g/kg body weight) for 22 d decreased the activities of the key enzymes for glycolysis and lipogenesis, and alanine aminotransferase activity. The findings presented here indicate a high level of metabolic adaptation to both diet type and ration size. In particular, adaptation of enzyme activities to the consumption of a diet with a high carbohydrate level suggests that a carnivorous fish like Sparus aurata can tolerate partial replacement of protein by carbohydrate in the commercial diets supplied in culture. The relationship between enzyme activities, ration size and fish growth indicates that the enzymes quickly respond to dietary manipulations of cultured fish.

Determination of some quality properties of marinated sea bream (Sparus Aurata L., 1758) during cold storage

In this study, it was aimed to determine the effect of sea bream (Sparus aurata) marinated some quality properties during cold storage. The fillets of fish were immersed into brine including 3.5% acetic acid 11% salt in the ratio of 1: 1.5 (fish: marinate brine) for marination process. After the process of ripening, samples were grouped into two and packed in plastic containers; one being plain (in sunflower oil) and the other being sauced (sauced prepared with sunflower oil). During storage, sensory, crude protein, lipid, dry matter and crude ash, TBA, TVB-N, TMA-N and peroxide analyses were done periodically. According to results of 200 days of storage, TVB-N values of sea bream marinates packaged as plain and sauced were 15.86/14.89 mg/100g, TBA 7.06/7.99 mg MA/kg, TMA-N 2.97/3.12, mg/100g, the value of peroxide was 7.23/7.45 meq/kg respectively. According to chemical and sensory analyses results obtained in the study; it was concluded that sea bream marinates packaged as plain and sauced can be stored in +4 °C for 200 days.