284 research outputs found

    Crecimiento en peces teleósteos

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    El crecimiento en los peces tele√≥steos, al igual que ocurre en otros grupos de animales, es el resultado de un complejo proceso en el que se ven implicados diversos factores (ambientales, endocrinos, nutricionales y gen√©ticos). Dentro de los factores endocrinos, existen diversos ejes que intervienen en el proceso de crecimiento. Entre estos ejes, el m√°s importante es el eje somatotr√≥pico, que incluye la hormona de crecimiento (GH), las somatomedinas (IGFI y II), los receptores de estas hormonas, as√≠ como las prote√≠nas de uni√≥n a la IGF (IGFBP). Sin embargo, otros ejes, tales como el eje hipot√°lamo-hipofisario-tiroideo (con las hormonas tiroideas T3 y T4 como productos finales), as√≠ como el eje hipot√°lamo-hipofisario-interrenal (con el cortisol como producto final), tambi√©n juegan un importante parel en el control endocrino del crecimiento. Dentro de los factores ambientales se pueden distinguir dos tipos: a) factores determinantes (temperatura, salinidad, fotoper√≠odo) que influyen directamente sobre el crecimiento aument√°ndolo o disminuy√©ndolo, y b) factores limitantes para los cu√°les existe un determinado umbral (NH4+ u ox√≠geno disuelto) o un margen de tolerancia espec√≠fico (pH). Entre los factores ambientales, la salinidad es un factor espec√≠fico del medio acu√°tico y que, por tanto, constituye una variable susceptible de ser modulada en el sector acu√≠cola. Las especies eurihalinas cultivadas (dorada, lenguado, lubina) pueden hacer frente a los cambios en la salinidad ambiental gracias a la actividad de su sistema osmorregulador. Sin embargo, estos procesos osmorreguladores requieren mucha energ√≠a y aquellas salinidades ambientales que disminuyan las necesidades energ√©ticas derivadas de los procesos osmorreguladores podr√≠an salvar energ√≠a y ayudar a maximizar el crecimiento. En la pr√°ctica acu√≠cola, el principal objetivo es la perfecta adaptaci√≥n del animal a las condiciones de cultivo. Esta adaptaci√≥n permitir√° el mantenimiento en cautividad, crecimiento y reproducci√≥n de la especie. Sin embargo, los posibles agentes estresantes en el cultivo de la especie son m√ļltiples y de variado origen (alimentaci√≥n deficiente, alta densidad de cultivo, baja oxigenaci√≥n del agua, condiciones f√≠sico-qu√≠micas del agua no √≥ptima, fotoperiodo y/o termoperiodo no adecuado, vibraciones y ruidos, etc). De este modo, la existencia de una situaci√≥n de estr√©s cr√≥nico en el cultivo originar√° una activaci√≥n del sistema de estr√©s con altos niveles de cortisol mantenidos durante tiempo (estr√©s cr√≥nico). Bajo estas circunstancias, el cortisol afecta negativamente al crecimiento, pues activa los procesos catab√≥licos en el tele√≥steoUniversidad de M√°laga. Campus de Excelencia Internacional Andaluc√≠a Tech

    Cultivo de especies de interés comercial en diferentes salinidades ambientales: dorada, corvina y pargo como ejemplos

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    El estrés, y en particular el estrés osmótico debido a la concentración salina del agua, es un factor muy relevante para la producción en acuicultura. En los teleósteos marinos cultivados, la exposición a un medio hiperosmótico impone en el animal la necesidad de osmorregular, lo cual implica un gasto energético importante. Este coste energético va en detrimento de la tasa de crecimiento de los peces, y por tanto de la productividad de la explotación acuícola. En la bahía de Cádiz existe una consolidada actividad de acuicultura, con un importante impacto económico en la región. Por ello, la optimización de la producción piscícola es de vital importancia. Una de los aspectos a considerar es el impacto de las variables ambientales sobre el cultivo, siendo de particular relevancia la temperatura, el fotoperiodo y la salinidad. En la facultad de Ciencias del Mar existe un centro de cría de especies de interés en acuicultura, e instalaciones adecuadas para la experimentación. Así, experimentos llevados a cabo con dorada y lenguado han permitido establecer que la salinidad del agua es un factor crítico para el crecimiento de los peces cultivados. Además, la salinidad óptima para el cultivo resultó ser diferente para cada especie, y por tanto debe ser optimizada de manera individual. Esto demuestra el coste energético que supone la osmorregulación en los peces, lo cual repercute en su crecimiento.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

    Metabolic and Stress Responses in Senegalese Soles (Solea senegalensis Kaup) Fed Tryptophan Supplements: E ects of Concentration and Feeding Period

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    The objective of this study was to assess the impact of di erent dietary Trp concentrations on the stress and metabolism response of juvenile Senegalese soles (Solea senegalensis). Fish (38.1 1.9 g) were fed di erent Trp-enriched feeds (0%, 1% and 2% Trp added) for two and eight days, and later exposed to air stress for three min. Samples were taken pre- and 1 h post-stress (condition). Plasma cortisol, lactate, glucose and proteins were significantly a ected by the sampling time, showing higher values at 1 h post-stress. Trp concentration in food also had significant e ects on lactate and glucose levels. However, the feeding period did not a ect these parameters. Post-stress values were higher than in the pre-stress condition for every plasma parameter, except for lactate in two days and 1% Trp treatment. Nevertheless, cortisol, glucose and lactate did not vary significantly between pre- and post-stress samplings in fish fed the 1% Trp-enriched diet for two days. The lack of variability in cortisol response was also due to the high pre-stress value, significantly superior to pre-stress control. The exposure time to Trp feeding did not significantly a ect any enzyme activity; however, Trp added and condition influenced protein-related enzyme activities. In spite of decreasing stress markers, Trp-enriched diets altered the protein metabolism

    Nuevos retos para la diversificación en acuicultura: la liseta (Chelon labrosus)

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    Chelon labrosus (Risso, 1827), commonly known as thicklip grey mullet, is a marine teleost fish from the Mugilidae family, very common in coastal and estuarine areas. It is characterized as an amphidromous species, migrating to brackish or lagoon waters to feedChelon labrosus (Risso, 1827), com√ļnmente conocida como lisa, liseta o corc√≥n, es un tele√≥s- teo marino de la Familia Mugilidae muy frecuente en zonas costeras y estu√°ricas. Se caracteriza por ser una especie anf√≠droma, migrando a aguas salobres o lagunares para alimentars

    Aflatoxicosis Dysregulates the Physiological Responses to Crowding Densities in the Marine Teleost Gilthead Seabream (Sparus aurata)

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    A fungal toxin, aflatoxin B1 (AFB1), undermines growth and stress axes of gilthead seabream (Sparus aurata) with depletion of somatic carbohydrate and lipid reservoirs. The present study assessed the physiological consequences of high stocking density versus low stocking density in seabream juveniles, which had previously been fed with AFB1 supplementation. These stressors are likely to converge by inferring animal welfare and economic profitability in the food animal industry. Interestingly, AFB1 seems to cause physiological and molecular dysfunction in response to overcrowding densities. Our results might be relevant to elucidate a potential risk for fish farming that is often overlooked. Several studies in fish have shown that aflatoxin B1 (AFB1) causes a disparity of species-dependent physiological disorders without compromising survival. We studied the effect of dietary administration of AFB1 (2 mg AFB1 kg(-1) diet) in gilthead seabream (Sparus aurata) juveniles in combination with a challenge by stocking density (4 vs. 40 g L-1). The experimental period duration was ten days, and the diet with AFB1 was administered to the fish for 85 days prior to the stocking density challenge. Our results indicated an alteration in the carbohydrate and lipid metabolites mobilization in the AFB1 fed group, which was intensified at high stocking density (HSD). The CT group at HSD increased plasma cortisol levels, as expected, whereas the AFB1-HSD group did not. The star mRNA expression, an enzyme involved in cortisol synthesis in the head kidney, presented a ninefold increase in the AFB1 group at low stocking density (LSD) compared to the CT-LSD group. Adenohypophyseal gh mRNA expression increased in the AFB1-HSD but not in the CT-HSD group. Overall, these results confirmed that chronic AFB1 dietary exposure alters the adequate endocrinological physiological cascade response in S. aurata, compromising the expected stress response to an additional stressor, such as overcrowding

    Vasotocin and isotocin regulate aquaporin 1 function in the sea bream

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    Aquaporins (AQPs) are specific transmembrane water channels with an important function in water homeostasis. In terrestrial vertebrates, AQP2 function is regulated by vasopressin (AVP) to accomplish key functions in osmoregulation. The endocrine control of aquaporin function in teleosts remains little studied. Therefore, in this study we investigated the regulatory role of vasotocin (AVTR) and isotocin (ITR) receptors in Aqp1 paralog gene function in the teleost gilthead sea bream (Sparus aurata). The complete coding regions of Aqp1a, Aqp1b, AVTR V1a2-type, AVTR V2-type and ITR from sea bream were isolated. A Xenopus oocyte-swelling assay was used to functionally characterize AQP1 function and regulation by AVT and IT through their cognate receptors. Microinjection of oocytes with Aqp1b mRNA revealed regulation of water transport via PKA (IBMX+forskolin sensitive), whereas Aqp1a mRNA injection had the same effect via PKC signaling (PDBU sensitive). In the absence of expressed receptors, AVT and IT (10(-8) mol l(-1)) were unable to modify AQP1 function. AVT regulated AQP1a and AQP1b function only when the AVTR V2-type was co-expressed. IT regulated AQP1a function, but not AQP1b, only when ITR was present. Considering that Aqp1a and Aqp1b gene expression in the sea bream intestine is highly salinity dependent in vivo, our results in ovo demonstrate a regulatory role for AVT and IT in AQP1 function in the sea bream in the processing of intestinal fluid to achieve osmoregulation.Ministry of Education (Spain) [FPU AP2008-01194]; Portuguese National Science Foundation [SFRH/BPD/66808/2009]; Ministry of Science and Education, Spain [AGL2010-14876]; National Science Foundation (FCT, Portugal) [PTDC/MAR-BIO/3811/2012

    La lampera marina a (Petromyzon marinus): Origen, evolución, historia y biología

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    Of all the existing vertebrates (more than 60,000 species), practically half (32,000) are fish. Within this group, more than 15,000 are strictly freshwater while only 225 are diadromous. Diadromy is a typical characteristic of species that perform migrations from the seas to the rivers, or vice versa associated with spawning. Modern lampreys (Petromyzontiformes) are one of the two surviving lineages of jawless fish (Agnathans), in addition to the hagfish (Myxini). Both lineages have survived at least four of the five mass extinctions that have occurred in the history of the Earth. These lineages diverged from a common ancestor.De todos los vertebrados existentes (m√°s de 60.000 especies), pr√°cticamente la mitad ( 32.000) son peces. Dentro de este grupo, m√°s de 15.000 son estrictamente dulceacu√≠colas mientras que solo 225 son di√°dromas. La diadrom√≠a es una caracter√≠stica t√≠pica de especies que realizan migraciones desde los mares hasta los r√≠os, o viceversa asociadas a la freza. Las lampreas modernas (Petromyzontiformes) son uno de los dos linajes supervivientes de peces no mandibulados (Agnathans), adem√°s de los myxines (Myxini). Ambos linajes han sobrevivido al menos a cuatro de las cinco extinciones masivas que se han producido la historia de la Tierra. Estos linajes divergieron de un ancestro com√ļn

    New Perspectives Related to the Bioluminescent System in Dinoflagellates: Pyrocystis lunula, a Case Study

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    Pyrocystis lunula is considered a model organism due to its bioluminescence capacity linked to circadian rhythms. The mechanisms underlying the bioluminescent phenomenon have been well characterized in dinoflagellates; however, there are still some aspects that remain an enigma. Such is the case of the presence and diversity of the luciferin-binding protein (LBP), as well as the synthesis process of luciferin. Here we carry out a review of the literature in relation to the molecular players responsible for bioluminescence in dinoflagellates, with particular interest in P. lunula. We also carried out a phylogenetic analysis of the conservation of protein sequence, structure and evolutionary pattern of these key players. The basic structure of the luciferase (LCF) is quite conserved among the sequences reported to date for dinoflagellate species, but not in the case of the LBP, which has proven to be more variable in terms of sequence and structure. In the case of luciferin, its synthesis has been shown to be complex process with more than one metabolic pathway involved. The glutathione S-transferase (GST) and the P630 or blue compound, seem to be involved in this process. In the same way, various hypotheses regarding the role of bioluminescence in dinoflagellates are exposed

    Crecimiento y cambios metabólicos anuales en corvina Argyrosomus regius cultivada en esteros

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    Metabolic modifications associated with natural environmental conditions were assessed in the meagre Argyrosomus regius cultured in earthen ponds under natural photoperiod and temperature. Juvenile specimens (90-100 g initial weight) were sampled (plasma, liver and muscle) every two months for 18 months (between December 2004 and May 2006). Specimens showed seasonal variations in growth rate, with the highest values in spring and summer. Plasmatic, hepatic and muscular metabolite levels and hepatic and muscular metabolic enzymes also showed significant variations throughout the year. Enzymatic activity related to carbohydrate metabolism in the liver (HK, FBPase and G6PDH) showed great modifications in summer, increasing glycogenogenic pathways, while amino acid metabolism (GDH and GOT activity) was enhanced in spring and summer. However lipid-related (G3PDH activity) metabolic enzymes did not show a clear seasonal pattern. In muscle, enzymatic activity related to amino acid, lipid and lactate metabolism (LDH-O activity), but not carbohydrate metabolism, showed seasonal changes in parallel with changes in growth rate. Thus A. regius specimens showed a trend to grow in summer months and mobilize their energy reserves in winter. Differences in the hepatic level were observed between the first and the second year of the study, suggesting the possible existence of metabolic changes related to specimen age or size. Our results indicate that growth and metabolic responses in A. regius are environmentally dependent and that this species is a very good candidate for diversification in aquaculture.Modificaciones metab√≥licas asociadas a condiciones ambientales temporales fueron evaluadas en la corvina Argyrosomus regius, cultivadas en esteros con fotoperiodo y temperatura natural. Ejemplares juveniles (90-100 g de peso inicial) fueron muestreados (plasma, h√≠gado y m√ļsculo) cada dos meses durante 18 meses (entre diciembre de 2004 y mayo de 2006). Las muestras mostraron variaciones estacionales en la tasa de crecimiento, con valores m√°s altos durante la primavera y el verano. Niveles de metabolitos plasm√°ticos, hep√°ticos y musculares, as√≠ como las actividades de enzimas metab√≥licas hep√°ticas y musculares tambi√©n presentaron variaciones significativas a lo largo del a√Īo. La actividad enzim√°tica relacionada con el metabolismo de carbohidratos en el h√≠gado (HK, FBPasa y G6PDH) mostr√≥ altas modificaciones en el verano, el aumento de las v√≠as glucogenog√©nicas, mientras el metabolismo de amino√°cidos (actividades de GDH y GOT) se increment√≥ en temporadas de primavera y verano. Sin embargo la actividad de G3PDH (enzima metab√≥lica relacionada con los l√≠pidos) no mostr√≥ un claro patr√≥n estacional. En el m√ļsculo, la actividad enzim√°tica respecto a los amino√°cidos, l√≠pidos y el metabolismo del lactato (LDH-O) present√≥ cambios estacionales en paralelo con los cambios en la tasa de crecimiento, pero el metabolismo de los carbohidratos no present√≥ cambios estacionales. As√≠ espec√≠menes de A. regius mostraron una tendencia a crecer en los meses de verano y movilizar sus reservas de energ√≠a en invierno. Se observaron diferencias en el nivel hep√°tico entre el primer y el segundo a√Īo de estudio, lo que sugiere la posible existencia de cambios metab√≥licos relacionados con la edad o el tama√Īo del esp√©cimen. Nuestros resultados indican que el crecimiento y las respuestas metab√≥licas en A. regius dependen del medio ambiente, pero tambi√©n indican que esta especie es una muy buena candidata para la diversificaci√≥n de la acuicultura
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