Vinchucas, Trypanosomas y demas familia: Nociones sobre la enfermedad de Chagas

La enfermedad de Chagas es, segun la Organization Mundial de la Salud, la enfermedad parasitaria mas grave en America Latina, y la principal causa de enfermedadescardiacas en esta region. Pese a ello, existe una gran ignorancia en la poblacion generalsobre lo que podriamos llamar su ciclo: como se transmite, como se manifiesta, y cualespueden ser los metodos para controlar esta enfermedad

Ausencia de efectos en los balances de nutrientes después de defoliación por insectos en una cuenca

Nutrient export via streamflow after the defoliation by Gonipterus scutellatus Gill. in a Eucalyptus globulus Labill. watershed in Galicia (NW Spain) was monitored from 1999 to 2006. The effects of such defoliation on nutrients balance had not been previously evaluated. Insect defoliation caused no significant changes in streamflow nutrient concentrations during the period of study compared with the pre-perturbation period and nutrient exports in streamflow were compensated via precipitation in all cases. The results presented here show that in spite of the reduction in E.globulus growth caused by the defoliation, nutrient balances were positive, suggesting a minor impact in the soil-plant system nutrient budget.Se ha desarrollado un estudio entre 1999 y 2006 para evaluar el efecto de la defoliación por Gonypterus scutellatus Gill. sobre la pérdida de nutrientes por escorrentía en una cuenca experimental de Eucalyptus globulus Labill. Galicia (NW España). Esos efectos no habían sido evaluados hasta ahora. La defoliación no causó variaciones significativas en las concentraciones de nutrientes durante el período de estudio en relación con el período pre-perturbación y las entradas de nutrientes por precipitación compensaron las salidas de nutrientes por escorrentía en todos los casos. Los resultados que se presentan en este trabajo muestran que a pesar de la reducción en el crecimiento de E.globulus causado por la defoliación, los balances de nutrientes fueron positivos, sugiriendo un impacto menor en el balance de nutrientes del sistema suelo-planta

Efectos de la secuencia incendio-corta a hecho-selección de brotes en la pérdida de nutrientes por escorrentía en una cuenca experimental de E. globulus en Galicia (NW de España)

An experimental study was carried out between 1987 and 1999, to assess the effect of the sequence wildfire-clearfelling-coppice sprout selection thinning, on streamflow nutrient export in a Eucalyptus globulus Labill. watershed in Galicia (NW Spain). The effects of such a sequence on nutrient export via streamflow had not been previously evaluated. A wildfire in 1989 caused a significant increase in nutrient exports in streamflow during the following two years. No significant effect was observed the third year after wildfire. After clearfelling in 1992, inputs via precipitation compensated for nutrient exports in streamflow, except for K the first year following harvest and NO3- during the three years after this operation. Coppice sprout selection thinning in 1995 had less effect on nutrient exports than wildfire or harvest. The results presented here could may help in evaluating the effects of current intensive forest management and perturbations that affect eucalypt stands in NW Spain.Se ha desarrollado un estudio entre 1987 y 1999 para evaluar el efecto de la secuencia incendio-corta a hecho-selección de brotes sobre la pérdida de nutrientes por escorrentía en una cuenca experimental de Eucalyptus globulus Labill. en Galicia (NW España). Esos efectos no habían sido evaluados hasta ahora. Un incendio en 1989 causó un aumento significativo de las pérdidas de nutrientes por escorrentía durante los dos años siguientes. Ningún efecto era apreciable al tercer año del incendio. Después de la corta a hecho del arbolado quemado en 1992, las entradas por precipitación compensaron las pérdidas por escorrentía, a excepción del K el primer año después de esta operación y del NO3- durante los tres años siguientes. La selección de brotes ejecutada en 1995 tuvo un efecto mucho menor en las pérdidas de nutrientes por escorrentía que el incendio o la corta. Los resultados que se presentan en este trabajo pueden ayudar a los gestores a evaluar los efectos del manejo intensivo y de las perturbaciones que afectan a las masas de eucalipto en el NW de España

Los problemas de lápiz y papel en la formación de profesores

In this article a didactic approach for both initial and ongoing teacher training is presented, oriented towards the teaching and learning of paper and pencil problem-solving. Taking as a starting point teachers' ideas of the educational possibilities of the problems which are generally used in Science classes (objectives reached and specific procedures which they develop), it then goes on to analyse and evaluate concrete traditional and innovative problem-solving models. This study will also look at commentaries and results regarding the development of these activities from both in-service and trainee teachers. It is shown that these teachers initially accept the educational interest of such problems, and they consider the innovative model to be the most useful because, apart from motivating the students, it also develops research procedures which the traditional problems ignore, and which are fundamental in scientific training

PHF2 regulates homology-directed DNA repair by controlling the resection of DNA double strand breaks

Post-translational histone modifications and chromatin remodelling play a critical role controlling the integrity of the genome. Here, we identify histone lysine demethylase PHF2 as a novel regulator of the DNA damage response by regulating DNA damage-induced focus formation of 53BP1 and BRCA1, critical factors in the pathway choice for DNA double strand break repair. PHF2 knockdown leads to impaired BRCA1 focus formation and delays the resolution of 53BP1 foci. Moreover, irradiation-induced RPA phosphorylation and focus formation, as well as localization of CtIP, required for DNA end resection, to sites of DNA lesions are affected by depletion of PHF2. These results are indicative of a defective resection of double strand breaks and thereby an impaired homologous recombination upon PHF2 depletion. In accordance with these data, Rad51 focus formation and homology-directed double strand break repair is inhibited in cells depleted for PHF2. Importantly, we demonstrate that PHF2 knockdown decreases CtIP and BRCA1 protein and mRNA levels, an effect that is dependent on the demethylase activity of PHF2. Furthermore, PHF2-depleted cells display genome instability and are mildly sensitive to the inhibition of PARP. Together these results demonstrate that PHF2 promotes DNA repair by homologous recombination by controlling CtIP-dependent resection of double strand breaks.España Ministerio de Ciencia e Innovacion SAF2016-80626-REspaña, Fundación Canaria Instituto de Investigación Sanitaria de Canarias (FIISC) [PIFUN16/18

Modelling aboveground biomass and fuel load components at stand level in shrub communities in NW Spain

Shrub-dominated ecosystems cover large areas globally and play essential roles in ecological processes. Aboveground biomass expressed on an area basis (AGB) is central to many of the ecological processes and services provided by shrublands and is important as the main fuel source for wildfires. Hence, its accurate estimation in shrublands is crucial for ecologists and land managers. This is especially relevant in fire-prone regions such as NW Spain, where shrublands are an important part of the landscape, providing multiple services, but are severely impacted by wildfires. Although biomass models are available for numerous shrub species at the individual plant level, operational models based directly on easily measured shrub stand attributes are scarce. In this study, equations for estimating AGB and loads of different fuel components by size and condition (live and dead) from stand biometric variables were developed for the nine most prevalent shrub communities in NW Spain. Non-linear iterative seemingly unrelated regression was used to fit compatible systems of equations for estimating fuel loads, with shrub stand height and cover and litter depth as predictors for individual shrub communities and all data combined. In general, the goodness-of-fit statistics indicated that the estimates were reasonably accurate for all communities (grouped and ungrouped). The best results were obtained for AGB and total fuel load, including litter, whereas the poorest results were obtained for standing live and dead fine fuel load. Model performance was reduced when height was the only independent variable, although the reduction was small for most fuel categories, except litter load for which the variability was adequately explained by the litter depth. These results illustrate the feasibility of the stand level approach for constructing operational models of shrub fuel load that are accurate for most of fuel components, while also highlighting the ongoing challenges in live and dead fine fuel modelling. The equations developed represent an appreciable advance in shrubland biomass assessment in the region and areas with similar characteristics and may be instrumental in generating fuel maps, fire management improvement and better C storage assessment by vegetation, among other many usesS

Variation of Hg concentration and accumulation in the soil of maritime pine plantations along a coast-inland transect in SW Europe

Financiado para publicación en acceso aberto: Universidade de Vigo/CISUGClimatic conditions have been shown as a major driver of the fate of Hg in forest ecosystems at a global scale, but less is known about climatic effects at shorter scales. This study assesses whether the concentration and pools of Hg in soils collected from seventeen Pinus pinaster stands describing a coastal-inland transect in SW Europe vary along a regional climatic gradient. In each stand, samples of the organic subhorizons (OL, OF + OH) and the mineral soil (up to 40 cm) were collected and some general physico-chemical properties and total Hg (THg) were analyzed. Total Hg was significantly higher in the OF + OH than in the OL subhorizons (98 and 38 μg kg−1, respectively), favored by a greater organic matter humification in the former. In the mineral soil, mean THg values decreased with depth, ranging from 96 μg kg−1 in the 0–5 cm layers to 54 μg kg−1 in the deepest layers (30–40 cm), respectively. The average Hg pool (PHg) was 0.30 mg m−2 in the organic horizons (92% accumulated in the OF + OH subhorizons), and 27.4 mg m−2 in the mineral soil. Changes in climatic factors, mainly precipitation, along the coast-inland transect resulted in a remarkable variation of THg in the OL subhorizons, consistent with their role as the first receiver of atmospheric Hg inputs. The high precipitation rate and the occurrence of fogs in coastal areas characterized by the oceanic influence would explain the higher THg found in the uppermost soil layers of pine stands located close to the coastline. The regional climate is key to the fate of mercury in forest ecosystems by influencing the plant growth and subsequent atmospheric Hg uptake, the atmospheric Hg transference to the soil surface (wet and dry deposition and litterfall) and the dynamics that determine net Hg accumulation in the forest floor.Ministerio de Educación y Formación Profesional | Ref. FPU17/05484Ministerio de Ciencia e Innovación | Ref. PID 2021-125114OB-I00Consellería de Cultura, Educación e Universidade (Xunta de Galicia) | Ref. ED431C2021/46- GRCUniversidad de Vigo/CISU

Needle age and precipitation as drivers of Hg accumulation and deposition in coniferous forests from a southwestern European Atlantic region

Financiado para publicación en acceso aberto: Universidade de Vigo/CISUGVegetation and climate are critical in the biogeochemical cycle of Hg in forest ecosystems. The study assesses the influence of needle age and precipitation on the accumulation of Hg in needle biomass and its deposition by litterfall in thirty-one pine plantations spread throughout two biogeographical regions in SW Europe. Welldeveloped branches of Pinus pinaster were sampled and pine needles were classified according to 4 age classes (y0, y1, y2, y3). The concentration of total Hg (THg) was analyzed in the samples and Hg content in needle biomass and its deposition by litterfall were estimated. The concentration of total Hg (THg) increased with needle age ranging from 9.1 to 32.7 μg Hg kg−1 in the youngest and oldest needles, respectively. The rate of Hg uptake (HgR) three years after needle sprouting was 10.2 ± 2.3 μg Hg kg−1 yr−1, but it decreased with needle age probably due to a diminution in photosynthetic activity as needles get older. The average total Hg stored in needle biomass (HgWt) ranged from 5.6 to 87.8 mg Hg ha−1, with intermediate needle age classes (y1 and y2) accounting for 70% of the total Hg stored in the whole needle biomass. The average deposition flux of Hg through needle litterfall (HgLt) was 1.5 μg Hg m−2 yr−1, with the y2 and y3 needles contributing most to the total Hg flux. The spatial variation of THg, HgWt and HgLt decreased from coastal pine stands, characterized by an oceanic climate, to inland pine stands, a feature closely related to the dominant precipitation regime in the study area. Climatic conditions and needle age are the main factors affecting Hg accumulation in tree foliage, and should be considered for an accurate assessment of forest Hg pools at a regional scale and their potential consequences in the functioning of terrestrial ecosystems.Ministerio de Educación y Formación Profesional | Ref. FPU17/05484Xunta de Galicia | Ref. ED431C 2021/46-GRCXunta de Galicia | Ref. ED431F2018/06-EXCELENCIAXunta de Galicia | Ref. ED431C2018/0