Comments on the calculation of the specific growth rate in experiments with untagged individuals

Postprint1,006

Growth and digestive enzymes of Solea senegalensis Kaup, 1858 larvae weaned onto different commercial diets

The optimization of artificial diets in the weaning of the Senegal sole Solea senegalensis Kaup, 1858 is an essential part of improving production and promoting its culture. Feeds are very important in larval digestive development and affect survival after weaning. Some digestive enzymes (trypsin, chymotrypsin, alkaline phosphatase and leucine aminopeptidase) have been proposed as indicators of the larval nutritional status. In the present study, three commercial aquafeeds (Aglonorse, Microbaq and Gemma) were used in weaning the S. senegalensis larvae. Growth, survival and digestive enzymes of larvae reared with the different feeds were compared.Se determina el crecimiento y las enzimas digestivas de larvas de lenguado senegalés Solea senegalensis Kaup, 1858 destetadas con tres piensos. Las larvas fueron alimentadas con un nivel basal de nauplios de artemia y una cantidad creciente de pienso. Las larvas alimentadas únicamente con presas vivas presentaron mejores crecimientos y supervivencias (140 mg de peso fresco por larva y 97 %, respectivamente) que las coalimentadas con piensos (60 mg de peso fresco por larva y 91 %, respectivamente). La evolución del peso en los tratamientos con pienso no mostró diferencias entre ellos. La mortalidad fue menor entre las larvas alimentadas con artemia, seguidas del tratamiento Gemma, siendo mayor con Microbaq y Aglonorse, en este orden. El patrón de actividades enzimáticas digestivas fue similar en todos los tratamientos. A pesar del menor crecimiento, las larvas desarrollan de forma adecuada sus capacidades digestivas sin que el uso de piensos ocasione modificación alguna en las mismas.Instituto Español de Oceanografí

A meta-analysis of the effects of agricultural management on soil physical quality for different farm typologies across Europe

Póster presentado en la Conferencia EGU 2014, 27 Abril - 7 Mayo 2014, Viena, Austri

Some problems of the determination of best management practices to maintain the quality of agricultural soils

Póster presentado en la Conferencia ELS 2014, 22-25 Septiembre 2014, Bari, ItaliaIn spite of the great effort of scientific research exploring the influence of agricultural practices on soil quality, many aspects remain unclear, possibly precluding a more general adoption of the best management systems by farmers and land use planners. Among other causes of this knowledge gap, the wide variety of agricultural practices due to different climates, landforms, soils, and crop types make hard to find either a general best management system or at least common rules of larger applicability. Nevertheless the more important problem is that we usually consider soil as an invariant entity which does not change, or if it does, its changes are controlled. The purpose of this report is the discussion of the results of a meta-analysis of the effects of agricultural management practices on physical aspects of soil quality, throughout the published research data of countries of the central and western part of the European continent. Soil physical quality was evaluated through several indicators which were evaluated in the research reports found. The indicators were: bulk density, resistance to penetration, stability of aggregates, permeability and water and sediment yield. The results indicate that there are agricultural practices which could be classified as convenient, although their possible advantages are not always evident, as, for instance, direct drilling as compared to conventional tillage, where the farm operations induce a certain compaction not always alleviated in absence of tillage. To further explore some of the results, the evolution of some properties of a clay soil subject to a long term experiment in dry farming conditions in southern Spain is considered. The evolution of the soil properties must be taken into account, for a more precise evaluation of the efficiency of management practices

Characterization of digestive proteases in the Senegal sole Solea senegalensis Kaup, 1858

The digestive proteases of Senegal sole Solea senegalensis Kaup, 1858 were studied. Acid proteases showed their peak of activity between pH:2.0 and pH:2.5. Optimum activity for intestinal proteases was found in the range of pH:9.5-10.0. The results of acid protease stability under different pH indicated that only pH 12.0 affect these enzymes. Alkaline proteases were highly sensitive to acidic pH. Temperature optimums were found at 37-40 °C. Thermal stability analysis showed that proteases kept up their activities until 50 °C. The use of specific proteases inhibitors showed the presence of aspartic proteases in stomach and serine proteases (trypsin and chymotrypsin-like) in the intestine. Zymograms confirm the existence of a single protease in stomach extract, and seven active fractions in the intestine extracts.Se caracterizan las proteasas digestivas de Solea senegalensis Kaup, 1858. El óptimo de actividad para el extracto estomacal se situó en valores de pH entre 2,0 y 2,5 y para los intestinales entre pH:9,5 y pH:10,0. El extracto de estómago se mostró muy estable a distintos valores de pH, excepto a pH:12,0. Los extractos intestinales mostraron ser inestables a pH ácido. Los óptimos de temperatura se localizaron entre 37 y 40 °C. Las proteasas fueron termolábiles por encima de 50 °C. El uso de sustratos e inhibidores específicos evidenció la presencia mayoritaria de pepsina en el estómago y de serina proteasas de tipo tripsina y quimotripsina en el intestino. Los zimogramas confirmaron la existencia de una sola proteasa en el extracto de estómago y de siete fracciones activas en el intestino.Instituto Español de Oceanografí

Probiotic supplementation influences the diversity of the intestinal microbiota during early stages of farmed Senegalese sole (Solea senegalensis, Kaup, 1858)

Ingestion of bacteria at early stages results in establishment of a primary intestinal microbiota which likely undergoes several stages along fish life. The role of this intestinal microbiota regulating body functions is crucial for larval development. Probiotics have been proved to modulate this microbiota and exert antagonistic effects against fish pathogens. In the present study, we aimed to determine bacterial diversity along different developmental stages of farmed Senegalese sole (Solea senegalensis) after feeding probiotic (Shewanella putrefaciens Pdp11) supplemented diet for a short period (10–30 days after hatching, DAH). Intestinal lumen contents of sole larvae fed control and probiotic diets were collected at 23, 56, 87, and 119 DAH and DNA was amplified using 16S rDNA bacterial domain-specific primers. Amplicons obtained were separated by denaturing gradient gel electrophoresis (DGGE), cloned, and resulting sequences compared to sequences in GenBank. Results suggest that Shewanella putrefaciens Pdp11 induces a modulation of the dominant bacterial taxa of the intestinal microbiota from 23 DAH. DGGE patterns of larvae fed the probiotic diet showed a core of bands related to Lactobacillus helveticus, Pseudomonas acephalitica, Vibrio parahaemolyticus,and Shewanella genus, together with increased Vibri o genus presence. In addition, decreased number of clones related to Photobacterium damselae subsp piscicida at 23 and 56 DAH was observed in probiotic-fed larvae. A band corresponding to Shewanella putrefaciens Pdp11 was sequenced as predominant from 23 to 119 DAH samples, confirming the colonization by the probiotics. Microbiota modulation obtained via probiotics addition emerges as an effective tool to improve Solea senegalensis larviculture.En prens

Crecimiento y enzimas digestivas de larvas de Solea senegalensis Kaup, 1858 alimentadas con piensos comerciales

The optimization of artificial diets in the weaning of the Senegal sole Solea senegalensis Kaup, 1858 is an essential part of improving production and promoting its culture. Feeds are very important in larval digestive development and affect survival after weaning. Some digestive enzymes (trypsin, chymotrypsin, alkaline phosphatase and leucine aminopeptidase) have been proposed as indicators of the larval nutritional status. In the present study, three commercial aquafeeds (Aglonorse, Microbaq and Gemma) were used in weaning the S. senegalensis larvae. Growth, survival and digestive enzymes of larvae reared with the different feeds were compared.Se determina el crecimiento y las enzimas digestivas de larvas de lenguado senegalés Solea senegalensis Kaup, 1858 destetadas con tres piensos. Las larvas fueron alimentadas con un nivel basal de nauplios de artemia y una cantidad creciente de pienso. Las larvas alimentadas únicamente con presas vivas presentaron mejores crecimientos y supervivencias (140 mg de peso fresco por larva y 97 %, respectivamente) que las coalimentadas con piensos (60 mg de peso fresco por larva y 91 %, respectivamente). La evolución del peso en los tratamientos con pienso no mostró diferencias entre ellos. La mortalidad fue menor entre las larvas alimentadas con artemia, seguidas del tratamiento Gemma, siendo mayor con Microbaq y Aglonorse, en este orden. El patrón de actividades enzimáticas digestivas fue similar en todos los tratamientos. A pesar del menor crecimiento, las larvas desarrollan de forma adecuada sus capacidades digestivas sin que el uso de piensos ocasione modificación alguna en las mismas

Caracterización de las proteasas digestivas del lenguado senegalés Solea senegalensis Kaup, 1858

The digestive proteases of Senegal sole Solea senegalensis Kaup, 1858 were studied. Acid proteases showed their peak of activity between pH:2.0 and pH:2.5. Optimum activity for intestinal proteases was found in the range of pH:9.5-10.0. The results of acid protease stability under different pH indicated that only pH 12.0 affect these enzymes. Alkaline proteases were highly sensitive to acidic pH. Temperature optimums were found at 37-40 oC. Thermal stability analysis showed that proteases kept up their activities until 50 oC. The use of specific proteases inhibitors showed the presence of aspartic proteases in stomach and serine proteases (trypsin and chymotrypsin-like) in the intestine. Zymograms confirm the existence of a single protease in stomach extract, and seven active fractions in the intestine extracts.Se caracterizan las proteasas digestivas de Solea senegalensis Kaup, 1858. El óptimo de actividad para el extracto estomacal se situó en valores de pH entre 2,0 y 2,5 y para los intestinales entre pH:9,5 y pH:10,0. El extracto de estómago se mostró muy estable a distintos valores de pH, excepto a pH:12,0. Los extractos intestinales mostraron ser inestables a pH ácido. Los óptimos de temperatura se localizaron entre 37 y 40 oC. Las proteasas fueron termolábiles por encima de 50 oC. El uso de sustratos e inhibidores específicos evidenció la presencia mayoritaria de pepsina en el estómago y de serina proteasas de tipo tripsina y quimotripsina en el intestino. Los zimogramas confirmaron la existencia de una sola proteasa en el extracto de estómago y de siete fracciones activas en el intestino