Propuesta metodológica para el cálculo de indicadores ambientales en el engorde de machos vacunos en pastoreo

Antecedentes: En los últimos años se ha producido un incremento en la demanda mundial de carne de res. Esta situación ha conllevado a un crecimiento de los sistemas de explotación para satisfacer la demanda de la sociedad. Por consiguiente, esto implicaría un incremento de las acciones antrópicas. Objetivo: definir un método de análisis relacionado con la implicación medioambiental de los sistemas de engorde de vacunos en pastoreo, mediante la construcción de indicadores ambientales (IA). Métodos: A partir de este estudio se determinó un indicador global para engorde en pastoreo denominado Indicador Ambiental de Pastoreo (IAP). Este indicador global se cuantificó asignándole un factor de riesgo ambiental entre 0 y 100, constituidos por ocho índices parciales y cada uno se correspondió con una actividad de la explotación ganadera. Se aplicó una escala tipo Likert y se calcularon los pesos estimados para cada índice parcial sobre la base de consultas realizadas a diferentes expertos. Resultados y conclusiones: Se concluye que el método propuesto permite el estudio y la evaluación de los impactos ambientales en los sistemas de ganado de engorde en pastoreo. Asimismo, constituye una base fundamental para la construcción de índices medioambientales en otros sistemas de producción, donde se podría sustituir las actividades del ganado de engorde por las que correspondan. El método constituye una herramienta valiosa para la detección de impactos y el planteamiento de medidas enfocadas a mitigarlos en cualquier área de producción. Palabras clave: Impacto ambiental, Ganado de carne, Recursos naturales (Fuente: BIREME

Cholesterol and membrane phospholipid compositions modulate the leakage capacity of the swaposin domain from a potato aspartic protease (StAPs-PSI).

Potato aspartic proteases (StAPs) and their swaposin domain (StAsp-PSI) are proteins with cytotoxic activity which involves plasma membrane destabilization. The ability of these proteins to produce cell death varies with the cellular type. Therefore, StAPs and StAsp-PSI selective cytotoxicity could be attributed to the different membrane lipid compositions of target cells. In this work we investigate the possible mechanism by which StAPs and StAsp-PSI produce selective membrane destabilization. Results obtained from leakage assays show that StAsp-PSI is a potent inducer of the leakage of LUVs containing anionic phospholipids, especially those containing phosphatidylglycerol. Based in these results, we suggest that the cytotoxic activity of StAsp-PSI on pathogenic microorganisms could be mediated by the attraction between the exposed positive domains of StAsp-PSI and the negatively charged microorganism membrane. On the other hand, our circular dichroism spectroscopic measurements and analysis by size exclusion chromatography and followed by electrophoresis, indicate that hydrophobic environment is necessary to StAsp-PSI oligomerization and both StAsp-PSI disulfide bounds and membrane with negative charged phospholipids are required by StAsp-PSI to produce membrane destabilization and then induce cell death in tumors and microorganism cell targets. Additionally, we demonstrate that the presence of cholesterol into the LUV membranes strongly diminishes the capacity of StAsp-PSI to produce leakag

Membrane interaction of segment H1 (NS4BH1) from hepatitis C virus non-structural protein 4B

AbstractNS4B protein from hepatitis C virus (HCV) is a highly hydrophobic protein inducing a rearrangement of endoplasmic reticulum membranes responsible of the HCV replication process. Different helical elements have been found in the N- and C- terminal domains of the protein, which seem to be responsible for many key aspects of the viral replication process. In this work we have carried out a study of the binding and interaction with model biomembranes of peptide NS4BH1, patterned after segment H1, one of these C-terminal previously identified segments. We show that NS4BH1 partitions into phospholipid membranes; its membrane activity is modulated by lipid composition, interacting preferentially with negatively charged phospholipids as well as with sphingomyelin. Furthermore, the change in its sequence prevents the resulting peptide from interacting with the membrane. These data would support its role in the interaction of NS4B with the membrane and suggest that the region where this peptide resides could be involved in the membrane alteration which must occur in the HCV replication and/or assembly process

Possible mechanism of structural transformations induced by StAsp-PSI in lipid membranes

In the present work we have analyzed the effect of StAsp-PSI (plant-specific insert of potato aspartic protease) on the structural and thermotropic properties of the major phospholipid types of bacterial and animal cells. Results obtained suggest that StAsp-PSI induces a destabilization of the membrane bilayers, depending on the time of interaction between the protein and the bilayers, rather than on its concentration. This temporal delay would be consistent with a lateral diffusion of StAsp-PSI monomers to assemble into aggregates to form pores. Like with the results previously reported for the StAsp-PSI circular dichroism, data obtained here from IR spectroscopy show that there are slight changes in the StAsp-PSI secondary structure in the presence of lipid membranes; suggesting that these changes could be related with the StAsp-PSI self-association. Results obtained from steady-state fluorescence anisotropy and differential scanning calorimetry assays suggest that StAsp-PSI interacts with both uncharged and negatively charged phospholipids, modulates the phase polymorphic behavior of model membranes and partitions and buries differentially in the membrane depending on the presence of negatively charged phospholipids

N-terminal AH2 segment of protein NS4B from hepatitis C virus : binding to and interaction with model biomembranes

© 2013 Elsevier B.V. All rights reserved.HCV NS4B, a highly hydrophobic protein involved in the alteration of the intracellular host membranes forming the replication complex, plays a critical role in the HCV life cycle. NS4B is a multifunctional membrane protein that possesses different regions where diverse and significant functions are located. One of these important regions is the AH2 segment, which besides being highly conserved has been shown to play a significant role in NS4B functioning. We have carried out an in-depth biophysical study aimed at the elucidation of the capacity of this region to interact, modulate and disrupt membranes, as well as to study the structural and dynamic features relevant for that disruption. We show that a peptide derived from this region, NS4BAH2, is capable of specifically binding phosphatidyl inositol phosphates with high affinity, and its interfacial properties suggest that this segment could behave similarly to a pre-transmembrane domain partitioning into and interacting with the membrane depending on the membrane composition and/or other proteins. Moreover, NS4BAH2 is capable of rupturing membranes even at very low peptide-to-lipid ratios and its membrane-activity is modulated by lipid composition. NS4BAH2 is located in a shallow position in the membrane but it is able to affect the lipid environment from the membrane surface down to the hydrophobic core. The NS4B region where peptide NS4BAH2 resides might have an essential role in the membrane replication and/or assembly of the viral particle through the modulation of the membrane structure and hence the replication complex.This work was partially supported by grants REEQ/140/BIO/2005, PTDC/QUI-BIQ/114774/2009 and PTDC/QUI-BIQ/112929/2009 to M.R.B.C (FCT-MES, Portugal). H. N. is supported by a “Santiago Grisolía” fellowship from Generalitat Valenciana Autonomous Government, Spain. F.P.J. acknowledges FEBS for a Short Term Fellowship

Trophic structure and energy fluxes around a Mediterranean fish farm

A fish farm in Southeastern Spain was described using an Ecopath mass-balanced model, aimed at characterising its structure, the interactions among ecological groups and the impact of fish farms and fisheries. The model comprised 41 functional groups (including the artificial food input). Comparing consumption and respiration to total system throughput suggests lower energy use in the fish farm, resulting in an accumulation of detritus. The production to total system throughput ratio was low due to the low efficiency of the modelled ecosystem. The connectance and system omnivory indexes were low, typical of a simple or immature food web in terms of structure and dynamics. Artificial food pellets provided energy and nutrients to sustain system function and generate a considerable reserve from which it can draw to meet unexpected perturbations. The study shows the substantial effect the artificial food pellets have on the wild aggregated fishes, which could act to buffer the ecosystem and hence prevent environmental degradation.Conselleria d’Educació, Generalitat Valenciana. MARTORRES. The study forms part of the ACUFISH project (Department of Marine Science and Applied Biology, University of Alicante) and was funded by Spanish Ministry of Science Grant MYCT-REN2003-00794

Noninvasive ventilation for severely acidotic patients in respiratory intermediate care units : Precision medicine in intermediate care units

Severe acidosis can cause noninvasive ventilation (NIV) failure in chronic obstructive pulmonary disease (COPD) patients with acute hypercapnic respiratory failure (AHRF). NIV is therefore contraindicated outside of intensive care units (ICUs) in these patients. Less is known about NIV failure in patients with acute cardiogenic pulmonary edema (ACPE) and obesity hypoventilation syndrome (OHS). Therefore, the objective of the present study was to compare NIV failure rates between patients with severe and non-severe acidosis admitted to a respiratory intermediate care unit (RICU) with AHRF resulting from ACPE, COPD or OHS. We prospectively included acidotic patients admitted to seven RICUs, where they were provided NIV as an initial ventilatory support measure. The clinical characteristics, pH evolutions, hospitalization or RICU stay durations and NIV failure rates were compared between patients with a pH ≥ 7.25 and a pH < 7.25. Logistic regression analysis was performed to determine the independent risk factors contributing to NIV failure. We included 969 patients (240 with ACPE, 540 with COPD and 189 with OHS). The baseline rates of severe acidosis were similar among the groups (45 % in the ACPE group, 41 % in the COPD group, and 38 % in the OHS group). Most of the patients with severe acidosis had increased disease severity compared with those with non-severe acidosis: the APACHE II scores were 21 ± 7.2 and 19 ± 5.8 for the ACPE patients (p < 0.05), 20 ± 5.7 and 19 ± 5.1 for the COPD patients (p < 0.01) and 18 ± 5.9 and 17 ± 4.7 for the OHS patients, respectively (NS). The patients with severe acidosis also exhibited worse arterial blood gas parameters: the PaCO levels were 87 ± 22 and 70 ± 15 in the ACPE patients (p < 0.001), 87 ± 21 and 76 ± 14 in the COPD patients, and 83 ± 17 and 74 ± 14 in the OHS patients (NS)., respectively Further, the patients with severe acidosis required a longer duration to achieve pH normalization than those with non-severe acidosis (patients with a normalized pH after the first hour: ACPE, 8 % vs. 43 %, p < 0.001; COPD, 11 % vs. 43 %, p < 0.001; and OHS, 13 % vs. 51 %, p < 0.001), and they had longer RICU stays, particularly those in the COPD group (ACPE, 4 ± 3.1 vs. 3.6 ± 2.5, NS; COPD, 5.1 ± 3 vs. 3.6 ± 2.1, p < 0.001; and OHS, 4.3 ± 2.6 vs. 3.7 ± 3.2, NS). The NIV failure rates were similar between the patients with severe and non-severe acidosis in the three disease groups (ACPE, 16 % vs. 12 %; COPD, 7 % vs. 7 %; and OHS, 11 % vs. 4 %). No common predictive factor for NIV failure was identified among the groups. ACPE, COPD and OHS patients with AHRF and severe acidosis (pH ≤ 7.25) who are admitted to an RICU can be successfully treated with NIV in these units. These results may be used to determine precise RICU admission criteria