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The common dentex, Dentex dentex , is an iconic marine coastal fish of the Mediterranean Sea. Despite its economic and ecological importance, data on the population structure of this species are still very limited. The aim of this study was to identify the stock structure of the common dentex at relatively fine spatial scale around Corsica Island, using a combination of markers that have different spatial and temporal scales of integration: microsatellite DNA markers, otolith shape analysis and parasites communities. Microsatellite analysis indicated that there was no significant genetic differentiation in D . dentex between the four sampling sites around Corsica. Otolith shape analysis suggests one potential distinct population unit of D . dentex centered in one site (Cap Corse) varying in their degree of differentiation from those in the other zones. Multivariate analysis on parasite abundance data highlights to a lower extent two sites (Bonifacio and Galeria) with some connectivity between adjacent zones. The combination of these three markers together highlights the resulting three sites while giving complementary insights and an opportunity to compare their utility and potential to understand population interactions. A complex population structure around Corsican coasts is then proposed, providing a new perspective on common dentex fishery stock conservation and management strategies. [ABSTRACT FROM AUTHOR]

Common dentex ( Dentex dentex ) is an appreciated carnivorous fish with high growth rate and life cycle adaptable to existing farming techniques. Since the use of carbohydrates is an economic and sustainable alternative for a protein-sparing effect, the study of how this macronutrient affects the welfare of carnivorous species must be studied. The aim of the present study was to evaluate the effects of different types and levels of carbohydrates on common dentex oxidative status. Nine isonitrogenous (43%) and isoenergetic (22 MJ kg − 1 ) diets were formulated combining three types (pregelatinized starch-PS, dextrin-Dx and maltodextrin-Mx) and three levels (12, 18 and 24%) of carbohydrates. The activities of catalase-CAT, superoxide dismutase-SOD, glutathione peroxidase-GPX, glutathione reductase-GR and glucose 6-phosphate dehydrogenase-G6PDH, SOD isoenzymatic profile, lipid peroxidation-LPO and protein oxidation-PO were determined in liver and white muscle. SOD and CAT were not affected. GPX in liver and white muscle and GR in liver increased at higher inclusion carbohydrates levels. The lowest levels of GR and G6PDH in both tissues and LPO in liver were observed in maltodextrin groups. No significant effects by carbohydrate source were observed in liver PO and white muscle LPO. Regarding carbohydrate level effect, 18% and 24% dietary inclusion level decreased LPO in white muscle and PO in liver. LPO in liver was also decreased at 24% inclusion level. Altogether, results indicate the use of carbohydrates as an alternative energy source does not produce negative effects on oxidative status of common dentex, on the contrary, even contribute to their oxidative protection. [ABSTRACT FROM AUTHOR]

Abstract The egg quality of two common dentex captive broodstocks were monitored for two consecutive years during their natural spawning season. Volume of spawned eggs, volume of buoyant eggs, fertilization rate, egg weight, hatching rate and mortality of larvae were recorded. According to the volume of spawned eggs, the ratio of buoyant eggs spawned, the number of spawning days and the fertilization rate pointed to an improvement from Year 1 to Year 2. But data on hatching rate and larval mortality lead to the opposite conclusion. Highlights • Two common dentex captive broodstocks have been monitored during their natural spawning season for two consecutive years. • The quality of the spawned eggs has been assessed using different quality criteria based on egg production or larval performance. • Criteria used for assessing the spawning quality lead to different conclusions. • In conclusion, all criteria should be used in order to obtain a reliable assessment, including criteria based on larval performance. [ABSTRACT FROM AUTHOR]

The present study was aimed to evaluate the capacity of common dentex ( Dentex dentex ) to efficiently use dietary carbohydrates. So, the effects of different type and levels of carbohydrates on growth performance, feed utilization, fish composition, plasma metabolites and key metabolic pathways in liver and white muscle of common dentex are presented. Nine isonitrogenous (43%) and isoenergetic (22 MJ kg − 1 ) diets were formulated combining three types, pregelatinized starch (PS), dextrin (Dx) and maltodextrin (Mx), and three levels (12, 18 and 24%) of carbohydrates. Growth performance was not significantly influenced by treatments. The best feed utilization was observed in 18% Mx group. Higher hepatic lipid content was found in fish fed lower dietary carbohydrate levels. PS induced higher liver and white muscle hexokinase and pyruvate kinase activities compared to the lower values observed for Mx. Malic enzyme and glucose 6-phosphate dehydrogenase in liver and white muscle were lower in Mx group. The influence of dietary carbohydrates source was more noticeable than those induced by the carbohydrate level, when glycolysis and lipogenesis pathways were considered. Common dentex is able to use properly dietary carbohydrates, although optimal dietary inclusion levels are below 24%. The greater protein-sparing effect was promoted by the less complex carbohydrate (maltodextrin) and the best feed utilization indices were obtained at intermediate levels of inclusion (18%). [ABSTRACT FROM AUTHOR]

Abstract: Since the timing of the lipovitellin heavy chain (LvH) of vitellogenin Ab (VtgAb) degradation during marine teleosts ontogeny is poorly understood, the current study was planned to address some aspects of this shortcoming. Fertilized eggs (before epiboly) of Dentex dentex were analysed. Vtg-derived proteins, that appeared as 6 protein bands after SDS-PAGE, were purified using specific ion exchange chromatography. Five bands (i.e., ∼78, ∼57, ∼22, ∼19, and ∼17 kDa) were merely stained with Coomassie Blue and one band (i.e., ∼16 kDa) only with Periodic Acid Schiff (PAS). The ∼16 kDa protein band was subjected to a mass spectrometry-based sequencing. These results showed that the ∼16 kDa protein band contains a mixture of “LvH-Ab” derivatives with the same molecular weight. The specific staining system (i.e., PAS) also revealed the glycosylation of some of the LvH-Ab fragments inside the ∼16 kDa protein band. The study provides new data about fragmentation of the LvH-Ab in marine pelagophil teleosts. [Copyright &y& Elsevier]

Abstract: Free amino acids (FAAs) play a key role in the physiology of marine teleosts (eggs, embryos, and larvae). However, the relationship between the egg FAAs content and the production of viable embryos and larvae (at different developmental stages) in batch spawner pelagophils has not yet comprehensively been investigated. Viable eggs of common dentex, Dentex dentex, were obtained from captive broodstocks. Egg wet weight (WW), dry weight (DW), and water content (%W) and viability parameters, or VPs (egg floating rate [FR], hatching rate [HR], and larval survival rate [SR] at days 0 to 5 posthatch) were determined for 45 egg batches. The egg batches were classified according to their HR magnitude. Twelve egg batches with the same WW, DW, and %W were taken from the same broodstock and at the same developmental stage to determine the qualitative and quantitative composition of FAAs. The total FAA (TFAA) content, glutamic acid (Glu), asparagine (Asn), glutamine (Gln), and arginine (Arg) were correlated with VPs. The Glu was significantly correlated with HR and SR at 0 day posthatch (dph), the Asn with SR at 1 dph, and the Gln and Arg with FR and HR. Of the 361 ratios made based on the absolute concentrations of FAAs, 24 ratios were correlated with VPs (P < 0.005) through 42 simple regression models (R2 =0.641 to 0.846). Of the 42 significant relationships found ∼10%, ∼28%, ∼12%, ∼30%, ∼8%, ∼4%, ∼2%, ∼2%, and ∼2% of the models show the relations of the egg FAAs ratios with FR, HR, SR at days 1 to 5 posthatch, and %W, respectively. A path coefficient in combination with a Pearson''s correlation coefficient provided a series of statistical evidences to show the effects of the egg FAAs interrelations on the relationships found between quantitative composition of a FAA and a VP. [Copyright &y& Elsevier]

Abstract: A wide range of antioxidant mechanisms are present in fish maintaining an adequate “oxidative balance”. When this balance tilts in favor of the oxidant agents “oxidative stress” arises with detrimental effects in molecules of great biological importance. Little has been reported about the influence of different dietary energy sources on antioxidant defenses in fish. The influence of different dietary macronutrient combinations on the key antioxidant enzyme activity, the oxidative damage to lipids and proteins and the possible modifications in the SOD isoenzymatic pattern were evaluated in liver, white muscle, heart and erythrocytes of common dentex (Dentex dentex). Four experimental diets with different protein:lipid:carbohydrate ratios (43/16/28; 43/24/4; 38/19/28 and 38/24/13) were formulated. In general, neither different dietary macronutrient levels nor the interaction among them induces substantial modifications in enzymatic antioxidant defense mechanisms. Two constitutive SOD isoforms, CuZn-SOD I and Mn-SOD, were detected in the tissues analyzed in all experimental groups, independently of diet formulation, but, a third SOD isoenzyme, CuZn-SOD II seems to be induced in white muscle by higher dietary protein levels. Densitometric analyses of western blotting membranes revealed higher CuZn-SOD expression in the heart of dentex fed on lower dietary protein levels, although these differences did not correlate with the SOD activity. Finally, a direct relation exists between the lipid or protein intake level and occurrence of oxidative damage in different tissue components. [Copyright &y& Elsevier]

Abstract: Digestive physiology of on-growing common dentex (Dentex dentex), including protease, amylase and lipase activity in stomach, pyloric caeca, anterior and posterior intestine, was evaluated. The influence of dietary macronutrient balance on these digestive processes was also assessed. Four experimental diets with different protein:lipid:carbohydrate ratios (43/16/28; 43/24/4; 38/19/28 and 38/24/13) were formulated. The highest activity for acid proteases was located in the stomach at pH 1.5. Alkaline proteolytic activities showed the highest values in the pyloric caeca and posterior intestine at pH 8.5–9.0. Dentex showed substantial amylase activity in the pyloric caeca and posterior intestine. Lipase activity was higher in the pyloric caeca, anterior and posterior intestine and was not detected in the stomach. Feed composition influenced alkaline protease activity in the anterior and posterior intestine and was higher for the diet with less protein and more carbohydrates. Enhanced amylase activity was observed in the pyloric caeca and posterior intestine in those groups fed on higher carbohydrate and lower lipid level diets. High dietary carbohydrate levels produced the highest lipase activity but this only occurred in the anterior intestine. We can conclude that the digestive tract of dentex adapts well to protein digestion and possesses a high potential for digesting the other dietary macronutrients, too. Dietary carbohydrate content seems to induce changes in protease, amylase and lipase activity. [Copyright &y& Elsevier]

Abstract: The aim of this study was to assess the potential effects of replacing part of the dietary protein by lipid or carbohydrate on the characteristics of dentex muscle. Dentex were hand-feed four isoenergetic diets (22.6 MJ kg−1 gross energy) with protein:lipid:carbohydrate ratios 43/16/28 (D1); 43/24/4 (D2); 38/19/28 (D3), and 38/24/13 (D4). At the end of the feeding period, biometric parameters, textural properties of muscle, as well as protein, lipid and collagen contents, and electrophoretic protein profiles of this tissue were studied. The decrease in dietary protein content improved textural parameters (increased firmness and water holding capacity). Within each dietary protein level, diets with high carbohydrate and low lipid contents resulted in lower values of muscle firmness than diets with low carbohydrate and high lipid contents. This increase in firmness matched with a lower muscle lipid and higher muscle collagen contents. SDS-PAGE separation of muscle extracts showed a higher relative contribution of myosin to total optical density in muscle from those animals fed lower dietary protein, although no significant difference in fish texture could be attributable to this finding. Results indicate a favourable effect of replacing protein by alternative energy sources (lipids or carbohydrates) on the rheological properties of muscle in this species, this improvement was more noticeable when protein was replaced by lipid than by carbohydrate. [Copyright &y& Elsevier]

Abstract: The influence of the dietary macronutrient balance on the intermediary metabolism of common dentex (Dentex dentex L.) was evaluated. Four experimental diets combining high and low levels of macronutrients were formulated. Dentex fed on 43% protein had higher liver and muscle lipid content, corresponding with an increased hepatic G6PDH activity. This “excess” of hepatic lipids at higher protein levels could be used to obtain energy as would be reflected by hepatic HOAD. In the liver, 43% of dietary protein induced higher AlaAT and FBPase activities. Similarly, dentex fed on the P43C28 and P38C28 diets showed an increased hepatic and muscular gluconeogenic pathways (higher FBPase activity) from amino acids (elevated AlaAT) and/or glycerol (elevated GK). However, changes in glycemia were not observed among dietary treatments. At coronary level, the use of lower dietary protein induced an increase in the activity of glycolytic (PK and HK-IV) and lipolytic (HOAD) enzymes. Considering the overall results and the experimental conditions, it could be suggested that dietary protein could be reduced until 38% without affecting negatively the normal physiology of dentex. Moreover, high dietary carbohydrate levels could not be used efficiently by dentex given that gluconeogenesis occurs. [Copyright &y& Elsevier]

Abstract: The digestive physiology of common dentex was studied by assessing the activity of different pancreatic (trypsin, chymotrypsin, amylase and lipase), intestinal (alkaline phosphatase, aminopeptidase N, maltase and leuncine–alanine peptidase) and gastric (pepsin) enzymes from hatching until the juvenile stage (50 dph at 19 °C). Enzymes involved in the digestion of protein, lipid and carbohydrate were present in common dentex larvae at hatching and before the onset of exogenous feeding. The specific activity of trypsin and chymotrypsin in newly hatched larvae was higher than that of amylase and lipase, indicating the importance of these enzymes in the cleavage of yolk proteins and hatching, while after hatching, the activity of these serine proteases dramatically decreased, whereas lipase showed the opposite trend. A progressive shift in activity from alkaline to acid proteases was observed during larval development, reflecting that alkaline proteases were not longer the main digestive enzymes involved in protein digestion after the development of gastric glands and onset of acidic digestion. Lipase total activity in common dentex peaked at 35 dph and decreased after weaning. Diet change due to weaning might partially explain the decrease in lipase activity, although this change might be also indicative of a change in the nutritional requirements of this species, since the juveniles prefer diets with high protein levels than those with lower protein and higher lipid content. Regarding intestinal enzymes, leucine–alanine peptidase and alkaline phosphatase and aminopeptidase N were found in newly hatched larvae, while maltase was detected after the onset of exogenous feeding. The achievement of an efficient brush border membrane digestion takes place much earlier (6–12 dph) than in any of the studied species which might reflect the different metabolic profile and rapid growth of this species. [Copyright &y& Elsevier]

Abstract: The aim of this paper was to test the effectiveness of Inter-Simple Sequence Repeat (ISSR) technique in detecting specific molecular markers to genetically discriminate some species of teleost fish. As model species, we used four Mediterranean sea bream species (i.e. Diplodus annularis, D. puntazzo, D. sargus sargus, and D. vulgaris), and the common Mediterranean dentex Dentex dentex. Furthermore, the occurrence in our samples of two partially albino sparids (suspected, on a morphological basis, to probably belong to D. sargus sargus and to D. dentex, respectively) allowed ISSRs to be tested on doubtful specimens. Eight ISSR primers produced 95 out of 97 scorable polymorphic loci with a large number (63) of species-private bands. Maximum parsimony analysis, ΔK statistics, and assignment test were consistent in separating the five species and solving the taxonomic position of specimens of dubious attribution. The results obtained evidence the usefulness of ISSR markers in specimen and species identification, particularly when the morphological traits of fish make the classification problematic. [Copyright &y& Elsevier]

Abstract: The spawning quality, in terms of hatching rate, larval mortality at 3 and 5 days post-hatching (dph) and day of total mortality of two broodstock groups of common dentex was evaluated for 1 month in 2005. Several biochemical parameters including total lipid content, lipid class and fatty acid composition, carbohydrate content and metabolic enzyme activities were analysed in all the egg batches collected. Comparison was carried out between low- (mortality at 3 dph higher than 35%) and high-quality (mortality at 3 dph lower than 10%) batches. No differences were observed in lipid content and/or lipid class and fatty acid composition although a slightly higher content of neutral lipids was detected in high-quality batches. However, significant differences were obtained regarding carbohydrate composition and the activity of enzymes such as alkaline phosphatase and pyruvate kinase being higher in low-quality egg batches. [Copyright &y& Elsevier]

Abstract: Skin coloration patterns in fish are of great physiological, behavioural and ecological importance, can be considered as an index of animal welfare in aquaculture and as an important quality factor for the retail value, especially of red skinned fish. In the present study we developed an appropriate method for comparisons of the skin chromaticity parameters in wild (Pagrus pagrus, Pagrus caeruleostictus, and Dentex gibbosus) and farmed red skin Sparidae and investigated the effect of storage time on skin colour of farmed Pagrus pagrus. The three-dimensional characteristics of colour appearance (lightness — L ⁎, hue — H° ab and chroma —C ab ⁎) were calculated. A new index, named Entire Colour Index (ECI), was developed to express hue and chroma which as combined variables, cannot be considered separately. In all species there was a remarkable dorsoventral gradient in mean L ⁎ and H° ab , with the ventral area being statistically significant brighter than the dorsal one. ECI value was species specific but did not show any statistically significant dorsoventral gradient, with the exception of P. pagrus. Skin melanin and carotenoids content presented differences between the Pagrus and the Dentex species that may explain the differences in the observed chromaticity pattern. Storage time affected lightness and hue only in the dorsal skin area. However, the effect of storage on ice was better reflected in mean ECI value which showed a marked decrease from Day 3 to Day 7 in both the dorsal (Day 0: 8.96±0.40; Day 7: 2.86±0.29) and ventral (Day 0: 8.97±0.18; Day 7: 4.10±0.29) skin area. Our results provide data for a non-subjective determination of skin colour pattern and show that ECI offers a good index of the actual colour in a meaningful and objective way. [Copyright &y& Elsevier]

Abstract: The aim of this work was to evaluate the effects of prolonged starvation and refeeding on antioxidant status and some metabolic-related parameters in common dentex (Dentex dentex) liver. Fish deprived of food for 5 weeks showed a significant increase in lipid peroxidation, measured as malondialdehyde (MDA) levels. The activity of the antioxidative enzymes superoxide dismutase (SOD), catalase, and glutathione peroxidase (GPX) in starved fish significantly increased (by 42%, 22%, and 52%, respectively), whereas glutathione reductase (GR) activity was significantly depressed by 53% compared to controls. No qualitative changes in the SOD isoenzymatic pattern were detected by nondenaturing PAGE analysis, but the isoforms corresponding to CuZn-SOD I and II were enhanced in starved fish. The activity of the enzymes indicative of oxidative metabolism, β-hydroxyacyl CoA dehydrogenase (HOAD) and citrate synthase (CS), significantly increased (by 123% and 28%, respectively), and that of glucose-6-phosphate dehydrogenase (G6PDH) was inhibited by 56%. Oxidative damage under these circumstances is reversible since all biomarkers assayed returned to control values after refeeding. Our results show that prolonged starvation leads to a pro-oxidant situation and oxidative stress despite activation of antioxidant defense mechanisms, and that inhibition of G6PDH activity might be responsible for this failure in cellular antioxidant defenses. [Copyright &y& Elsevier]

This study describes the evolution of tissue composition and serum metabolites of common dentex (Dentex dentex) in different maturity stages. During maturation, diet and perivisceral fat provide the materials needed for the development of gonads. Female and male fish had higher total proteins, total fat, triglycerides (TG) and cholesterol in their serum, at spawning and spermiation, respectively. The examination of dentex tissues (muscle, liver and gonad) revealed no statistically significant differences (P<0.05) in energy density and lipid content during different maturity stages and there was no conclusive evidence that energy density and lipid content differ between sexes. In muscle, liver and gonad triglycerides fraction, the proportion of saturated fatty acids (FA) was greater than the proportion of polyunsaturated fatty acids (PUFA), whereas the reverse observation was made (with the exception of liver) in the polar lipid (PL) fraction of the above tissues. In muscle and liver, the main polyunsaturated fatty acids (n-3 PUFA) were docosahexaenoic (DHA, 22:6n-3) and eicosapentaenoic (EPA, 20:5n-3) acids. The main n-6 polyunsaturated fatty acids were linoleic (18:2n-6) and arachidonic (20:4n-6) acids. Palmitic (16:0) and oleic (18:1n-9) acids were the main saturated fatty acids and monoenes, respectively. The relative concentration of the major fatty acids varied seasonally and a pattern can be seen in both mature and immature dentex. In the PL fraction of muscle, higher values of total saturated and n-3 fatty acids, palmitic acid and DHA were obtained during summer in comparison to winter samplings; this trend was also shown by the total saturated fatty acids in the TG fraction. [Copyright &y& Elsevier]

Dentex is considered suitable for aquaculture due to its ready adaptation to culture systems, acceptance of formulated feeds and rapid growth rates. However, little information on the nutritional requirements or growth rates under controlled conditions has been reported for this fish. Thus, two feeding trials were performed, at different growth stages, to identify suitable protein and lipid (energy) levels to be used in formulating dry diets for this species. As the first step, a 3×2 factorial experiment was conducted to determine the optimum protein-to-energy (P/E) ratio for fingerling dentex. Triplicate groups were fed to satiation one of six practical diets with increasing levels of protein (50%, 53% and 57% DM) and two energy levels (20 and 22 kJ g-1) within each protein level. Protein utilization was enhanced by a sparing effect of dietary lipid at 19.7%. These data suggest that, when the energy level of the diet is maintained at 22 kJ g-1, the dietary protein level for fingerling dentex can be lowered from 57% to 50%. In the second experiment, with larger fish, triplicate groups of fish were fed one of six diets with two energy levels (20 and 22 kJ g-1) and three P/E ratios (19, 21 and 23 g MJ-1). Thus, the dietary protein level tested ranged from 38.7% to 51.14% DM. The results in the second trial suggest that, when protein efficiency or retention are considered, even dietary levels of 43.4% CP and 19 g protein MJ-1 of P/E, and a calculated available energy level (22 kJ g-1) could be assumed to be adequate levels for formulating practical diets for this species at this growth stage. It can be concluded that, for the two size classes of dentex used, dietary lipid had a protein-sparing effect. [Copyright &y& Elsevier]

Dentex fingerlings weighing 2.5 g initial live weight were fed 12 extruded diets containing four crude protein levels (40%, 45%, 50% and 55%) and three crude lipid levels (12%, 17% and 22%) according to a factorial design, for 6 weeks. Survival was high (84–92%) and specific growth rate (SGR) values were 3.4%, 3.9%, 4.3% and 4.1% day−1 and food conversion ratio (FCR) were 2.2, 2.1, 1.5 and 1.9 for fish fed the diets containing 40%, 45%, 50% and 55% crude protein, respectively. With respect to lipid levels, SGR values were 4.2%, 4.0% and 3.6% day−1 and FCR were 1.7, 1.8 and 2.3 for 12%, 17% and 22% crude lipid, respectively. The effects of protein and lipid levels were significant; final live weight, SGR, FCR and PER values were best for fish fed 50% crude protein and poorest for those fed 22% lipid diets. The best growth performance was observed in fish fed diets containing 50/12 and 50/17 protein/lipid ratios. The results indicate that optimum growth and nutrient utilisation of dentex fingerlings can be obtained when they are fed a diet containing around 50% crude protein with a lipid level ranging from 12% to 17%, and having a crude protein/gross energy ratio from 22 to 25 g MJ−1. [Copyright &y& Elsevier]

The formation of annuli was examined from scales and otoliths of farmed (known age) common dentex, Dentex dentex. One scale annulus formed each year during May and one hyaline zone on the otoliths during June. The formation of scale annuli and the hyaline zone on otoliths of adult fish coincided with gonadal maturation which takes place during April to May. Scales were found to be more accurate than otoliths in respect to annuli formation, but their annuli were not as intense and distinct. Missing or additional hyaline zones were observed on adult otoliths. These irregularities were observed after fish maturation and were related to temperature conditions, as well as to faster growth of the farmed fish than the wild ones. [Copyright &y& Elsevier]