Accumulation and Decomposition Rates and N, P and K Returned to the Soil by the Litter of Tropical Legumes and Grasses

The return of plant nutrients through litter decomposition of legumes and grasses is important for the sustainability of grassland ecosystems (Sánchez et al., 1989). Therefore, the selection of species that produce high amounts of decomposable litter is important . The objective of the present work was to study the production and decomposition rates of litter from various legumes and grasses in Cuba

Validation of the Software “Recycling of Nutrients” in Dairy-Farms of Western Cuba

To maintain a good productivity in the soil-plant-animal system it is necessary to achieve an equilibrium between input and output of nutrients and energy. Models and simulation software have been proposed for this purpose. For dairy farms, models have been utilised to show the behaviour of different aspects, such as: feed utilisation, energy flow, digestibility values and daily weight gains (Freer et al., 1970; Assis & France, 1983, Bruce et al., 1984). However, there are few models showing the interaction between soil-plant- animal components of these systems. The objective of the present study was to validate the software Recycling of Nutrients proposed by Ortiz (2000) for dairy farms of western Cuba

Anti-mycobacterial activity of labdane and halimane diterpenes obtained from Plectranthus ornatus Codd

Biomedical and biopharmaceutical research : jornal de investigação biomédica e biofarmacêuticaOs produtos naturais são uma fonte única de compostos-tipofpara o desenvolvimento de fármacos em química medicinal. Vários diterpenos das espécies Plectranthus foram referidos com actividade tuberculostática interessante, sendo que o P. omatus Codd. é usado como anti-infeccioso em algumas regiões do Brasil. Em trabalhos anteriores, um diterpeno de esqueleto de halimano outro labdano foram isolados a partir de P. ornatus Codd. Neste trabalho, avaliou-se preliminarmente a sua actividade micobacteriana com uma estirpe não virulenta de Mycobacterium smegmatis. A citotoxicidade dos compostos foi testada medindo a libertação de lactato desidrogenase (LDH) não sendo encontrados efeitos citotóxicos consideráveis até 25 ug/mL. Posteriormente, o método de microdiluição foi utilizado para determinar a concentração mínima inibitória (CMI) de M. smegmatis. A CMI>99% para o esqueleto de halimano foi 100 ug/mL e >100 ug/mL para o esqueleto de labdano. De acordo com o nosso conhecimento, este é o primeiro estudo usando diterpenos de esqueleto de halimano e de labdano isolados a partir de P. omatus em ensaios de citotoxicidade em macrófagos, e num ensaio preliminar sobre a sua atividade anti-micobacteriana. Estudos futuros são sugeridos na estirpe virulenta de M. tugerculosis, particularmente para os diterpenos de esqueleto de halimano.Plectranthus spp. have been reported to have interesting tuberculostatic activity and P. ornatus Codd. has been used in some regions of Brazil as an anti-infective. Previously, diterpenes with halimane and labdane skeletons were isolated in large quantities from P. ornatus Codd. We assessed the anti-mycobacterial activity of these compounds, performing a preliminar assay with the non-virulent strain Mycobacterium smegmatis. The cytotoxicity of the diterpenes with halimane and labdane skeletons was tested with the lactate dehydrogenase assay, where no considerable cytotoxic effects were found up to 25 μg.mL-1. Subsequently, the microdilution method was used to determine the minimum inhibitory concentration (MIC) against M. smegmatis. The MIC that inhibited the growth of the non-virulent mycobacteria by ≥99% was 100 μg.mL-1 for the diterpene with halimane skeleton, whereas for the diterpene with a labdane skeleton was >100 μg.mL-1. To the best of our knowledge, this is the first report on diterpenes with halimane and labdane skeletons isolated from P. ornatus in macrophages cytotoxicity, and in a preliminar assay for anti-mycobacterial activity. Further studies are suggested on M. tuberculosis, particularly for the diterpenes with halimane skeleton

Estudio de la toxoplasmosis y sarcosporidiosis de ganada bovino de la provincia de Granada (España)

The variations in the content of free amino acids in fruits during ripening is a matter of interest since these compounds are related to their flavour, taste and structure. This study was designed to determine the changes of free amino acids in ripening cherimoya fruits (Annona cherimolia var. Fino de Jete), evaluating the influence of the storage temperature afier harvesting. Methanolic fruit extracts of epicarp and mesocarp were used for quantification of free amino acids which were analyzed by ion-exchange chromatography. Citrulline and proline were detected in relatively high amounts. Glutamate, glutamine, aspartate, asparagine and the non proteinogenic taurine, y-aminobutyric and yaminoadipic acids were found in concentrations that varied between 2-6% of the total free amino acids content. Ripening increased the contents of amino acids, mainly proline,  citrulline and glutamate when cherimoya storage at 20 oC or 80 oC. These increases did not occur when the storage temperature was maintained at 4 oC suggesting that chilling injury markedly affects the synthesis pathway of proline from glutamate.Las variaciones en el contenido de aminoácidos libres en frutos durante la maduración es un tema de interés debido a la relación de estos compuestos con su olor, sabor y estructura. Este estudio se ha diseñado para determinar los cambios en aminoácidos libres durante la maduración de los frutos del chirimoyo (Annona cherimolia varo Fino de Jete), evaluando la influencia de la temperatura de almacenamiento después de la recolección. Extractos metanólicos de epicarpio y mesocarpio del fruto se usaron para la cuantificación de los aminoácidos libres, los cuales fueron analizados por cromatografia de intercambio iónico. Citrulina y prolina se detectaron en cantidades relativamente altas. Glutamato, glutamine, aspartato, asparragina y los no proteinogenéticos taurina, ácido yaminobutíricoy ácido a-aminoadípico fueron encontrados en concentraciones que variaron entre 2-6% del total del contenido de aminoácidos libres. La maduración incrementó el contenido de aminoácidos, sobre todo de prolina, citrulina y glutamato, cuando los chirimoyos se almacenaron a 20 oC o 8 oc. Este incremento no ocurrió cuando la temperatura de almacenamiento se mantuvo a 4 oC, sugiriendo que el daño por frío afecta marcadamente a la vía de síntesis de la prolina a partir de glutamato

Morris-Thorne wormholes with a cosmological constant

First, the ideas introduced in the wormhole research field since the work of Morris and Thorne are briefly reviewed, namely, the issues of energy conditions, wormhole construction, stability, time machines and astrophysical signatures. Then, spherically symmetric and static traversable Morris-Thorne wormholes in the presence of a generic cosmological constant are analyzed. A matching of an interior solution to the unique exterior vacuum solution is done using directly the Einstein equations. The structure as well as several physical properties and characteristics of traversable wormholes due to the effects of the cosmological term are studied. Interesting equations appear in the process of matching. For instance, one finds that for asymptotically flat and anti-de Sitter spacetimes the surface tangential pressure of the thin-shell, at the boundary of the interior and exterior solutions, is always strictly positive, whereas for de Sitter spacetime it can take either sign as one could expect, being negative (tension) for relatively high cosmological constant and high wormhole radius, positive for relatively high mass and small wormhole radius, and zero in-between. Finally, some specific solutions with generic cosmological constant, based on the Morris-Thorne solutions, are provided.Comment: latex, 49 pages, 8 figures. Expanded version of the paper published in Physical Review

Properties of OB star−black hole systems derived from detailed binary evolution models

Context. The recent gravitational wave measurements have demonstrated the existence of stellar mass black hole binaries. It is essential for our understanding of massive star evolution to identify the contribution of binary evolution to the formation of double black holes. Aims. A promising way to progress is investigating the progenitors of double black hole systems and comparing predictions with local massive star samples, such as the population in 30 Doradus in the Large Magellanic Cloud (LMC). Methods. With this purpose in mind, we analysed a large grid of detailed binary evolution models at LMC metallicity with initial primary masses between 10 and 40 M⊙, and identified the model systems that potentially evolve into a binary consisting of a black hole and a massive main-sequence star. We then derived the observable properties of such systems, as well as peculiarities of the OB star component. Results. We find that ∼3% of the LMC late-O and early-B stars in binaries are expected to possess a black hole companion when stars with a final helium core mass above 6.6 M⊙ are assumed to form black holes. While the vast majority of them may be X-ray quiet, our models suggest that these black holes may be identified in spectroscopic binaries, either by large amplitude radial velocity variations (≳50 km s−1) and simultaneous nitrogen surface enrichment, or through a moderate radial velocity (≳10 km s−1) and simultaneous rapid rotation of the OB star. The predicted mass ratios are such that main-sequence companions can be excluded in most cases. A comparison to the observed OB+WR binaries in the LMC, Be and X-ray binaries, and known massive black hole binaries supports our conclusion. Conclusions. We expect spectroscopic observations to be able to test key assumptions in our models, with important implications for massive star evolution in general and for the formation of double black hole mergers in particular

Paleobiology of titanosaurs: reproduction, development, histology, pneumaticity, locomotion and neuroanatomy from the South American fossil record

Fil: García, Rodolfo A.. Instituto de Investigación en Paleobiología y Geología. Museo Provincial Carlos Ameghino. Cipolletti; ArgentinaFil: Salgado, Leonardo. Instituto de Investigación en Paleobiología y Geología. General Roca. Río Negro; ArgentinaFil: Fernández, Mariela. Inibioma-Centro Regional Universitario Bariloche. Bariloche. Río Negro; ArgentinaFil: Cerda, Ignacio A.. Instituto de Investigación en Paleobiología y Geología. Museo Provincial Carlos Ameghino. Cipolletti; ArgentinaFil: Carabajal, Ariana Paulina. Museo Carmen Funes. Plaza Huincul. Neuquén; ArgentinaFil: Otero, Alejandro. Museo de La Plata. Universidad Nacional de La Plata; ArgentinaFil: Coria, Rodolfo A.. Instituto de Paleobiología y Geología. Universidad Nacional de Río Negro. Neuquén; ArgentinaFil: Fiorelli, Lucas E.. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica. Anillaco. La Rioja; Argentin