Lasting temperature effects on the muscle tissue, body growth and fillet texture of adult turbots, Scophthalmus maximus, L.

In the teleosts, several factors can influence the muscle growth patterns of fish by a modulation of the hypertrophy and hyperplasia. The temperature (T) is one of the most important environmental factors. Thus, the T history of fish influences on their potential growth, as it has been observed in Salmon, Salmo salar (Johnston et al., 2003) and other species. The T imprinting can influence on the muscle cellularity throughout the advanced stages of life due to the lasting T effects on myogenic cells precursors (MPC) (Steinbacher et al., 2011). In different teleost species, a correlation between texture and muscle fibre size has been demonstrated (Hatae et al., 1990). Hence, the thermal history can also influence in the flesh texture. In the present work we study the lasting T effects in adult turbots reared at different Ts during the early phases. This species reaches ≈ 1.5 kg at 18-20 months of age and the first sexual maturity takes place at ≈ 24 month

Estudio de la celularidad en las diferentes regiones musculares de rodaballos diploides y triploides, Scophthalmus maximus L.

Se analizó la celularidad muscular en cuatro zonas del miotomo: epiaxial superior, hipoaxial superior, epiaxial interior e hipoaxial inlerior, en2 grupos de rodaballos: 7 diploides y 7 triploides. En diploides, las zonas epiaxiales (superior e interior) mostraron mayores valores del tamaOO (p0,05) que las hipoaxiales, siendo tales valores mayores en hembras que en machos. En triploides, ~ distribución librilar mostró algunas dilerencias respecto a diploides, observándose mayores valores del tamaño librilar en las regiones epie hipoaxiales de la zona superior del pez, mientras que el menor número y densidad de fibras fue encontrado en la región epiaxial superior. En relación al sexo, el tamaño librilar lue menor en hembras que en machos triploides, mientras que el resto de parámetros musculares mostraron generalmente mayores valores en hembras. Al comparar ambos grupos, la hipertrofia librilar fue mayor en triploides (P<0,05), en todas las zonas musculares (1-4).The muscle cellularily was analyzed in lour regions (epaxial upper. hipoaxial upper, epaxial bottom and hipoaxial bottom) en two populatioos ~ turbo!: 7 diploid and 7 triploid specimens. Diploid specimens showed higher values 01the size and number 01 whije fibres in the epaxial!han in!he hipoaxial zones, being such values higher in lemales than in males. In triploid specimens, the highest values olthe muscle fibres size were 100M!! !he upper zones (epaxial and hipoaxial), whereas!he lowest number and densijy 01libres was lound in !he epaxial upper zone. In relationtothesex influence in triploid, the lowest value 01Ihe muscle fibres size was lound in lemaJes, whereas Ihe rest 01 muscle parameters were higher in lemaIes. When comparing bolh groups, muscle hypertrophy was higherin triploid than in diploid specimens (P<0,05), in all the muscle zones (1-4)

The Effect of 17α-Ethynilestradiol and GPER1 Activation on Body and Muscle Growth, Muscle Composition and Growth-Related Gene Expression of Gilthead Seabream, Sparus aurata L

Endocrine-disrupting chemicals include natural and synthetic estrogens, such as 17α- ethynilestradiol (EE2 ), which can affect reproduction, growth and immunity. Estrogen signalling is mediated by nuclear or membrane estrogen receptors, such as the new G-protein-coupled estrogen receptor 1 (GPER1). The present work studies the effect of EE2 and G1 (an agonist of GPER1) on body and muscle parameters and growth-related genes of 54 two-year-old seabreams. The fish were fed a diet containing EE2 (EE2 group) and G1 (G1 group) for 45 days and then a diet without EE2 or G1 for 122 days. An untreated control group was also studied. At 45 days, the shortest body length was observed in the G1 group, while 79 and 122 days after the cessation of treatments, the shortest body growth was observed in the EE2 group. Hypertrophy of white fibers was higher in the EE2 and G1 groups than it was in the control group, whereas the opposite was the case with respect to hy- perplasia. Textural hardness showed a negative correlation with the size of white fibers. At the end of the experiment, all fish analyzed in the EE2 group showed a predominance of the gonadal ovarian area. In addition, the highest expression of the mafbx gene (upregulated in catabolic signals) and mstn2 (myogenesis negative regulator) was found in EE2 -exposed fish.Versión del editor2,46

DATOS BIOMÉTRICOS Y DE COMPOSICIÓN EN LUBINA DE TAMAÑO COMERCIAL (Dicentrarchus labrax L.) CULTIVADA A DIFERENTES TEMPERATURAS

Se estudió el crecimiento y algunos parámetros somatométricos (longitud total, a la horquilla, estándar, cefálica, y de la línea lateral; altura dorsal superior, anal, y dorsal inferior; índice de condición, cefálico, de compacidad, gonadosomático, hepatosomático, digestosomático, bazosomático, grasosomático y fracción comestible), así como la composición corporal, en lubinas de un peso de 350 g mantenidas a diferentes temperaturas desde la fertilización hasta el tamaño comercial. Los dos lotes sólo presentaron diferencias significativas en el contenido en cenizas (P0,05), que fue mayor en la población cultivada a alta temperatura. Se discutieron los resultados en relación con la temperatura. Estos resultados mostraron la escasa influencia del método de cultivo, lo que puede ser de interés por su posible efecto sobre la calidad final del producto.Biometric and composition data in sea bass, Dicentrarchus labrax (Linnaeus, 1758), of commercial size cultivated at different temperatures. Some somatometric parameters (total, fork, standard, head, and lateral line length; superior dorsal, anal, and inferior dorsal height; condition, cranial, compactness, gonadosomatic, hepatosomatic, digestosomatic, spleensoomatic, perivisceral fat and dressing index) and body composition of 350 g sea bass cultured under different temperatures from fertilization to commercial size were studied. We found significative differences (P0,05) between both groups only in ash content which was higher in the fish cultivated at high temperature. The results related to temperature are discussed. These data showed that there is no influence of culture temperature on characteristics and quality of the final product and that this fact can be of interest from the point of view of the aquaculture commercialization.CICYT. Proyecto AGL2000-1738-C03-0

Efecto de la triploidía sobre los parámetros musculares y nutricionales del rodaballo (Scophthalmus maximus, L.) después de su maduración sexual

Con el objetivo de una mejor comprensión de la calidad final del rodaballo triploide (Scophtha/mus maximus, L.), la celularidad musculary los parámetros de calidad de la carne fueron estudiados en 7 rodaballos diploides y 7 lriploides de 33 meses de edad, todos ejemplares decultivoy de un tamaño similar. La celularidad del músculo blanco se evaluó por medio del número y diámetro de las fibras musculares. Para determinarla calidad de la carne fueron analizados diversos parámetros físico-químicos (humedad, proteína, grasa y ácidos grasas totales) y se determinaIOO las propiedades mecánicas de la lextura (dureza, elasticidad, masticabilidad, cohe~ividad y gomosidad) con un texturómetro. El mecanismode crecimiento muscular difirió entre los dos grupos, de tal manera que el tamaño de las fibras fue mayor (p<O,OOI)en los triploides , mientrasquela densidad de fibras musculares fue mayor en el grupo de los diploides, lo que demuestra que las diferencias genéticas produjeron dtlerente celularidad muscular en ambos grupos. No se encontraron diferencias significativas en las propiedades texturales ni en los parámetros decalidad de la carne entre diploides y triploides.In order lo a beller understanding of Ihe final qualily of lriploid turbot (Scophthalmus maximus, L.), muscle cellularily and qualily parametersoflhe flesh were studied on 7 diploid and 7 triploid 33 months old farmed turbot of similar size. White muscle cellularily was evaluated by meansofIhe number and diameter of muscle fibers. lo ascertain the flesh qualily, several physlco-cbemlcal parameters (moisture, protein, total fat andfalty acids) were analyzed, and textural mechanical properties (hardness, springiness, chewiness, cohesiveness, gumminess) were determinedwitha texturometer. Muscle growth mechanism differed between both groups, such that muscie fibres size was greater (p<O,OOI)in triploid specimens, wihereas muscle fibre density was higher in diploid group, thus showing mat genetic differences produced different muscie cellularity in bothgroups. No significant differences were found in textural properties and flesh qualily parameters between diploid and triploid groups

Influence of Low Dietary Inclusion of the Microalga Nannochloropsis gaditana (Lubián 1982) on Performance, Fish Morphology, and Muscle Growth in Juvenile Gilthead Seabream (Sparus aurata)

A 90-d feeding trial was conducted in which five groups of gilthead seabream (11.96 g initial body weight) were fed with a microalgae-free diet (control group, C) or four diets containing the microalgae Nannochloropsis gaditana at two inclusion levels (2.5% or 5%), either raw (R2.5 and R5 batches) or cellulose-hydrolyzed (H2.5 and H5 batches), to study their effect on the body and muscle growth. At 40 days, the highest values of body length and weight were reached in R5 group, but at 64 and 90 days, these were reached in R2.5. However, feed conversion rate, specific growth, daily intake, and survival (100%) were similar in all the groups. The acquisition of a discoid body shape was accelerated depending on the inclusion level of N. gaditana in the diets. Moreover, H5 diet affected the fish geometric morphology compared to R5 diet. The white muscle transverse area was similar in all groups at 40 days, with the exception of H2.5 group, which showed the lowest area. At day 90, C and R2.5 displayed the highest muscle growth, attributable to increased hyperplasia in C, and higher hypertrophy in R2.5. However, the highest proportion of small and medium fibers was observed in R5 and H5Versión del edito

Body and muscle growth of prelarvae and larvae of turbot, scophthalmus maximus L., reared at three different temperatures

Three turbot groups were kept at 15˚C - 16˚C (Cold Temperature, T), 17˚C - 18˚C (ambient T) and 21˚C - 22˚C (warm T) during the larval development in order to study the thermal influence on muscle growth and larval development in this species. During the early stages (2 - 6 days of posthatching), the body and the muscle growth was scarce, although the hyperplasia increased slightly, being higher at ambient and at cold T than at warm T. In contrast, the highest value of hypertrophy was found in the warm group. At 15 days of age, the body length and muscle growth increased in all the groups, being significantly higher in the warm than in the rest of groups. Thus, the highest values of both the hypertrophy and the hyperplasia of the white muscle fibres were reached at warm T, although it was only significant for the hyperplasia. The end of the metamorphosis was reached at 29 days of age in the warm group, whereas in the rest of groups it was no observed yet. At this developmental stage, the warm group showed the typical morphological mosaic of the myotome, and it was accompanied by an increase of the transverse area of the white and the red muscles, parallel to an increase of both the hypertrophy and the hyperplasia of the muscle fibres. The hyperplasia of the white fibres was the parameter most significantly increased. Also, the body length increased significantly in this group, reaching ≈1.6 cm at this stage.Postprin

Evaluation of Nannochloropsis gaditana raw and hydrolysed biomass at low inclusion level as dietary functional additive for gilthead seabream (Sparus aurata) juveniles

Abundant research is being carried out in the last years aimed at exploring microalgal biomass as nutrient source for different species of aquacultured fish. Some microalgae species, such as Nannochloropsis gaditana, have thick cell walls rich in cellulose, which might well reduce the bioavailability of intracellular active compounds. Among the alternatives aimed at overcoming this limitation, cellulase enzyme hydrolysis is proposed as a convenient and practical solution. In this regard, an in vitro assay was carried out, in which N. gaditana biomass was treated with cellulase (5% w/w basis) and the release of soluble compounds (reducing sugars, free amino acids and total phenolics) into the reaction medium was measured and compared to untreated raw biomass. The results confirmed increased yields of those compounds as a result of the enzyme pre-treatment. A 90-d feeding trial was also carried out in order to assess in vivo the influence of the inclusion of N. gaditana in feeds on juvenile gilthead seabream (Sparus aurata) growth, digestive physiology and body composition. Microalgal biomass was added at two inclusion levels (25 and 50 g kg 1 dry weight) in four experimental feeds, either crude or enzymatically pretreated. Animals (15.1 g initial body weight) were randomly assigned to five dietary treatments (two inclusion levels, 2.5 and 5%, and two microalgae formats, raw and enzymatically hydrolysed, plus a microalgae-free control), and distributed triplicate tanks per dietary treatment. Fish were withdrawn after 45 and 90 days, and proximate composition, muscle fatty acid and amino acid profiles, muscle and liver lipid oxidation, instrumental skin colour, digestive enzyme activities, as well as structural and ultrastructural changes in the intestinal mucosa were determined. No differences attributable to the dietary treatments were found with regard to fish growth or proximate composition at the end of the feeding trial. On the contrary, the inclusion of microalgal biomass, irrespectively of the cellulase pre-treatment, caused beneficial effects on some physiological parameters (namely digestive mucosa structure and functionality, oxidative status of muscle lipids, and instrumental colour). The only clear improvement found in fish attributable to the cellulase pre-treatment of the microalgal biomass was related to the prevention of muscle lipid oxidation. Overall, the results suggest that N. gaditana used as additive (at inclusion level below 5%) in feeds might represent a valuable nutritional strategy for S. aurata juveniles, even if growth was not affected.Versión del editor2,04