Efecto de los gradientes de pastoreo ovino sobre la vegetación y el suelo en Península Valdés, Patagonia Argentina

La introducción de ganado doméstico provocó modificaciones en la vegetación y en el suelo de la Patagonia extra-andina. Estos cambios alteraron procesos ecosistémicos, aumentaron la desertificación y causaron pérdida de biodiversidad. Es frecuente encontrar gradientes decrecientes de actividad animal partiendo de las aguadas (piósferas), que resultan adecuados para determinar el impacto del pastoreo sobre los ecosistemas. El objetivo de este estudio fue evaluar el efecto de la intensidad de pastoreo ovino a partir de gradientes de piósfera sobre la estructura de la vegetación y el suelo en estepas arbustivas representativas de Península Valdés, Argentina. Mediante modelos lineales generalizados mixtos (GLMM) y técnicas multivariadas se estudiaron las variaciones en la cobertura vegetal, complejidad vertical de la vegetación, número y área de parches vegetados, microtopografía del suelo y su compactación en relación con el gradiente de pastoreo. La intensidad del pastoreo disminuyó con la distancia a la aguada y explicó más de 50% de la variabilidad ambiental. Esto demuestra la existencia de efecto piósfera. La cobertura de herbáceas, mantillo, complejidad vertical de la vegetación y la microtopografía aumentaron al disminuir la presión de pastoreo en los sitios más alejados de la aguada, mientras que el porcentaje de suelo desnudo, gravas, cobertura de anuales y la compactación del suelo presentaron un patrón opuesto. Este estudio evidencia, por primera vez, la existencia de piósferas ovinas en Península Valdés e indica que la intensidad de pastoreo en la región se asocia con alteraciones ambientales compatibles con procesos importantes de degradación ecosistémica. Dada la importancia que reviste la península en el contexto de la conservación biológica de la región, se requieren más estudios de este tipo para una implementación efectiva de medidas de manejo que integren la ganadería y la conservación de los recursos naturales.The introduction of domestic livestock in the arid Patagonia produced changes in vegetation and soil that altered fundamental ecosystem processes, increasing desertification and biodiversity loss. In this region, it is common to observe gradients of decreasing animal activity from watering points where livestock impact is greatest near the watering sites, called piospheres, particularly suitable for assessing the effect of grazing on arid ecosystems. The aim of this study was to evaluate the effect of sheep-grazing intensity using piospheres on the structure of the vegetation and soil in shrubby steppes of Peninsula Valdes, Argentina. Variation of plant cover, vertical complexity of the vegetation, number and area of vegetated patches, micro-topography and soil compaction in relation to piosphere gradients were studied using Generalized Linear Mixed Models (GLMM) and multivariate analyses. Grazing intensity decreased according to increasing distance to the watering point. This fact, explaining more than 50% of the overall environmental variability, confirmed the existence of a piosphere gradient on each studied site. Such environmental changes were characterized by a gradual increase in grass and litter cover, vertical complexity of vegetation and soil microtopography at increasing distances from the watering point. Percentages of bare soil and gravel, cover of annual grasses and soil compaction showed the opposite pattern. This study demonstrates, for the first time, the existence of sheep piospheres in the shrubby steppes of Peninsula Valdes. Our results indicate that sheep-grazing intensity is associated with changes in the structure and composition of the vegetation and the soil characteristics that are compatible with degradation processes in the study region. Taking into account the importance of Peninsula Valdes in the context of biodiversity conservation, more studies of this type are required to implement effective management actions integrating livestock and conservation efforts on the terrestrial ecosystems of the regionFil: Cheli, Germán H. CCT-CONICE-CENPAT. Instituto Patagónico para el Estudio de los Ecosistemas Continentales; Argentina. Universidad Nacional de la Patagonia San Juan Bosco. Facultad de Ciencias Naturales; ArgentinaFil: Pazos, Gustavo E. CCT-CONICE-CENPAT. Instituto Patagónico para el Estudio de los Ecosistemas Continentales; Argentina. Universidad Nacional de la Patagonia San Juan Bosco. Facultad de Ciencias Naturales; ArgentinaFil: Flores, Gustavo E. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto Argentino de Investigaciones de las Zonas Áridas. Laboratorio de Entomología; ArgentinaFil: Corley, Juan Carlos. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Bariloche. Grupo de Ecología de Poblaciones de Insectos; Argentin

FOOD HABITS OF THE MAGELLANIC HORNED OWL (BUBO MAGELLANICUS) IN A COASTAL ISLAND OF PATAGONIA, ARGENTINA

Abstract ∙ The Magellanic Horned Owl (Bubo magellanicus) is one of the most common nocturnal raptors in Patagonia. The aim of this note was to analyze the food habits of this species in a small island from the Patagonian Atlantic coast. Four nesting areas and eight adults of Bubo magellanicus were found; 217 pellets plus disaggregated material were collected. We identified 2774 individual prey items. Insects were the most consumed prey (63.56%), followed by reptiles (13.73%), arachnids (10.92%), mammals (10.42%), and birds (1.37%). Our study show B. magellanicus feeding mainly on arthropods and introduced species, a fact that was not previously reported for this species in Patagonia. Resumen ∙ Hábitos alimenticios del Tucúquere (Bubo magellanicus) en una isla de Patagonia, Argentina El Tucúquere (Bubo magellanicus) es una de las rapaces nocturnas más comunes de la Patagonia. El objetivo de esta nota fue analizar los hábitos alimenticios de esta especie en una pequeña isla de la costa atlántica de la Patagonia. Se encontraron cuatro áreas de nidificación y ocho adultos de Bubo magellanicus y se recolectaron 217 egagrópilas además de material disgregado. Identificamos 2774 individuos presa. Los insectos fueron la presa más consumida (63,56%), seguidos por los reptiles (13,73%), los arácnidos (10,92%), los mamíferos (10,42%) y las aves (1,37%). La relevancia de este estudio reside en que B. magellanicus se alimenta principalmente de artrópodos y especies introducidas, hecho que no se había reportado previamente para esta especie en la Patagonia.

Effects of putrescine, cadaverine, spermine, spermidine and β-phenylethylamine on cultured bovine mammary epithelial cells

A bovine mammary epithelial cell line (BME-UV1) and three-dimensional collagen primary bovine organoids were used to evaluate the effects of cadaverine, putrescine, spermine, spermidine and β-phenylethylamine on mammary epithelial cells. Each biogenic amine was diluted in several concentrations (0-50 mM in BME-UV1 and 0-4 mM in primary bovine organoids) in the appropriate saline solution for the cell culture considered. In order to determine the activity of each compound tritiated thymidine incorporation was used. At low concentrations, all amines induced cell proliferation in both cultures. In BME-UV1, spermine significantly inhibited cell proliferation (P<0.001), while the other amines inhibited at higher concentrations (50mM). In primary bovine organoids, β−phenylethylamine significantly (P<0.001) inhibited cell proliferation at 4 mM. Organoids cultured in the presence of all amines, except β-phenylethylamine, had stellate projections indicating intense cell proliferation. Proliferation of mammary epithelial cells was stimulated at low concentrations, while at high concentrations it was inhibited. Our results suggested that the effects of each compound on mammary epithelial cells could be related to the compound itself and not to mediating by the bovine amino oxidase, responsible of the formation of toxic metabolites

Role of alpha-tocopherol in counteracting DNA damage induced by Ochratoxin A in primary porcine fibroblasts

Ochratoxin A is a mycotoxin responsible for disease states in both humans and animals. OTA mechanisms of action are numerous, including lipid peroxidation. Oxidative damage results in the modification of macromolecules (i.e. DNA), cell death and tissue injure. Several strategies, such as the use of antioxidants, have been used to reduce OTA cytotoxicity. The aim of this study was to evaluate the role of alpha-tocopherol in counteracting DNA damage induced by OTA in cell cultures. Primary porcine fibroblasts, isolated from embryo and from ear, were incubated for 24h with several concentrations of OTA in order to detect DNA fragmentation. OTA produced DNA fragmentation in a concentration dependent manner in both primary cell cultures. The pre-treatment with alpha-tocopherol caused the reduction of DNA fragmentation in both primary cell cultures, after 24h of incubation with OTA. In particular, when OTA was added at 10 µg/ml in embryo fibroblasts, alpha-tocopherol at the concentrations of 1 nM was significantly (P<0.05) able to reduce DNA fragmentation by 16%. In ear fibroblast cultures, alpha-tocopherol at the 1nM concentration was significantly (P<0.05) able to reduce DNA fragmentation by 15.23% in the presence of 5 µg/ml of OTA

A Conditional Zebrafish MITF Mutation Reveals MITF Levels Are Critical for Melanoma Promotion vs. Regression In Vivo

The microphthalmia-associated transcription factor (MITF) is the “master melanocyte transcription factor” with a complex role in melanoma. MITF protein levels vary between and within clinical specimens, and amplifications and gain- and loss-of-function mutations have been identified in melanoma. How MITF functions in melanoma development and the effects of targeting MITF in vivo are unknown because MITF levels have not been directly tested in a genetic animal model. Here, we use a temperature-sensitive mitf zebrafish mutant to conditionally control endogenous MITF activity. We show that low levels of endogenous MITF activity are oncogenic with BRAFV600E to promote melanoma that reflects the pathology of the human disease. Remarkably, abrogating MITF activity in BRAFV600Emitf melanoma leads to dramatic tumor regression marked by melanophage infiltration and increased apoptosis. These studies are significant because they show that targeting MITF activity is a potent antitumor mechanism, but also show that caution is required because low levels of wild-type MITF activity are oncogenic

Clinical and genetic determinants of nevirapine plasma trough concentration

Background: Only few data are available on the influence of CYP2B6 and CYP3A4/A5 polymorphisms on nevirapine plasma concentrations in the Caucasian population. Our aim was to assess the impact of CYP2B6 and CYP3A4/A5 polymorphisms on nevirapine plasma concentrations consecutively collected. Methods: We retrospectively analyzed clinical data of all HIV-positive patients who were followed at the Infectious Diseases Unit, DIBIC Luigi Sacco, University of Milan between January 2000 and December 2015. All patients with at least one nevirapine plasma trough concentration (NVP Cmin) determination were tested for CYP2B6 c.516 G>T, CYP3A4*22C>T and CYP3A5*3 A>G polymorphisms. Univariate and multivariate regression analyses were carried out considering NVP Cmin as the dependent variable and genetic polymorphisms and clinical characteristics as independent variables. Results: A total of 143 patients were evaluated. Most of them were males (61.5%) and Caucasian (92.3%). Overall, NVP Cmin varied from 1571 to 14,189\u2009 ng/mL (median\u2009 =\u2009 5063\u2009 ng/mL, interquartile range\u2009 =\u2009 3915\u20136854). The median NVP Cmin significantly differed in patients with different CYP2B6 genotypes, but did not vary in those with different CYP3A phenotypes. In the final general linear model, factors significantly associated with a higher NVP Cmin were each extra unit of T alleles of CYP2B6 rs3745274 (\u3b2\u2009 =\u2009 0.328, 95% confidence interval\u2009 =\u2009 0.172\u20130.484; p\u2009 <\u2009 0.0001), older age (\u3b2\u2009 =\u2009 0.362, 95% confidence interval\u2009 =\u2009 0.193\u20130.532; p\u2009 <\u2009 0.0001) and hepatitis C virus coinfection (\u3b2\u2009 =\u2009 0.161, 95% confidence interval\u2009 =\u2009 0.006\u20130.315; p\u2009 <\u2009 0.041). Conclusion: Our study, conducted in a prevalent Caucasian population, highlighted the importance of CYP2B6 genetic variants in influencing nevirapine plasma trough concentration. Furthermore, older age and hepatitis C virus coinfection significantly increase exposure to nevirapine

Pharmacokinetics and pharmacogenetics of SSRIs during pregnancy : An observational study

Background: An involvement of selective serotonin reuptake inhibitors (SSRIs) in increasing the risk of malformations, neonatal withdrawal syndrome, has been suggested recently. Here, we aimed to investigate the contribution of individual pharmacogenetics of SSRI on infants' outcome. We also estimated the umbilical/maternal plasma SSRI concentration ratio in the pregnant women still on SSRI therapy at the time of delivery. Methods: Thirty-four pregnant women, referred to our hospital from January 2011 to July 2015, who were given SSRIs in the third trimester, and related children, were considered. The umbilical/maternal plasma SSRI concentration ratio was estimated in 15 mothers still on SSRI therapy at the time of delivery. For patients with pharmacokinetic analyses, blood samples were collected for pharmacogenetic analyses. Results: Nineteen newborns presented clinical signs possibly related to drug toxicity. A high umbilical/maternal plasma ratio of SSRI was observed in 10 of the 15 evaluated newborns. Five mothers were intermediate metabolizers and 1 a poor metabolizer for the major CYP enzyme involved in pharmacokinetic pathway. Conclusions: Individualized psychopharmacologic treatment that takes into account the mother's exposure to SSRI concentrations and eventually her genetic background may become the standard of care to maximize drug benefit and minimize risks to the newborn

Autophagy as a new therapeutic target in Duchenne muscular dystrophy

A resolutive therapy for Duchene muscular dystrophy, a severe degenerative disease of the skeletal muscle, is still lacking. Because autophagy has been shown to be crucial in clearing dysfunctional organelles and in preventing tissue damage, we investigated its pathogenic role and its suitability as a target for new therapeutic interventions in Duchenne muscular dystrophy (DMD). Here we demonstrate that autophagy is severely impaired in muscles from patients affected by DMD and mdx mice, a model of the disease, with accumulation of damaged organelles. The defect in autophagy was accompanied by persistent activation via phosphorylation of Akt, mammalian target of rapamycin (mTOR) and of the autophagy-inhibiting pathways dependent on them, including the translation-initiation factor 4E-binding protein 1 and the ribosomal protein S6, and downregulation of the autophagy-inducing genes LC3, Atg12, Gabarapl1 and Bnip3. The defective autophagy was rescued in mdx mice by long-term exposure to a low-protein diet. The treatment led to normalisation of Akt and mTOR signalling; it also reduced significantly muscle inflammation, fibrosis and myofibre damage, leading to recovery of muscle function. This study highlights novel pathogenic aspects of DMD and suggests autophagy as a new effective therapeutic target. The treatment we propose can be safely applied and immediately tested for efficacy in humans

Clinical and genetic factors associated with increased risk of severe liver toxicity in a monocentric cohort of HIV positive patients receiving nevirapine-based antiretroviral therapy

BackgroundNevirapine has been used as antiretroviral agent since early 90. Although nevirapine is not currently recommended in initial anti-HIV regimens, its use remains consistent in a certain number of HIV-1-positive subjects. Thus, our aim was to determine clinical and genetic factors involved in the development of severe nevirapine induced liver toxicity.MethodsWe retrospectively analyzed all HIV positive patients who were followed at the Infectious Diseases Unit, DIBIC Luigi Sacco, University of Milan from May 2011 to December 2015. All patients treated with nevirapine who underwent a genotyping for the functional variants mapping into ABCB1, CYP2B6, CYP3A4 and CYP3A5 genes were included in the analysis. Severe hepatotoxicity was defined as ACTG grade 3-4 AST/ALT increase during the first three months of nevirapine treatment. The causality assessment between NVP exposure and drug-induced liver injury was performed by using the updated Roussel Uclaf Causality Assessment Methods. Hardy Weinberg equilibrium was tested by (2) test. A multivariable logistic regression model was constructed using a backward elimination method.ResultsThree hundred and sixty-two patients were included in the analysis, of which 8 (2.2%) experienced a severe liver toxicity. We observed no differences between patients with and without liver toxicity as regards gender, ethnicity, age and immune-virological status. A higher prevalence of HCV coinfection (75.0% vs 30.2%; p=.0013) and higher baseline AST (58IU/L vs 26IU/L; p=0.041) and ALT (82IU/L vs 27IU/L; p=0.047) median levels were observed in patients with liver toxicity vs those without toxicity. The genotypes CT/TT at ABCB1 rs1045642 single nucleotide polymorphism (SNP), showed a protective effect for liver toxicity when compared with genotype CC (OR=0.18, 95%CI 0.04-0.76; p=0.020) in univariate analysis. In the multivariate model, HCV coinfection was independently associated with higher risk of developing liver toxicity (aOR=8.00, 95%CI 1.27-50.29; p=0.027), whereas ABCB1 rs1045642 CT/TT genotypes (aOR=0.10, 95%CI 0.02-0.47; p=0.004) was associated with a lower risk.ConclusionsAccording to our findings HCV coinfection and ABCB1 rs1045642 SNP represent independent determinants of severe liver toxicity related to nevirapine. This genetic evaluation could be included as toxicity assessment in HIV-1-positive subjects treated with nevirapine