Joan Nogué i Font

Interactive effects of UV radiation and reduced precipitation on the seasonal leaf phenolic content/composition and the antioxidant activity of naturally growing Arbutus unedo plants

The effects of UV radiation and rainfall reduction on the seasonal leaf phenolic content/composition and antioxidant activity of the Mediterranean shrub Arbutus unedo were studied. Naturally growing plants of A. unedo were submitted to 97% UV-B reduction (UVA), 95% UV-A+UV-B reduction (UV0) or near-ambient UV levels (UVBA) under two precipitation regimes (natural rainfall or 10-30% rainfall reduction). Total phenol, flavonol and flavanol contents, levels of eight phenols and antioxidant activity [DPPH(●) radical scavenging and Cu (II) reducing capacity] were measured in sun-exposed leaves at the end of four consecutive seasons. Results showed a significant seasonal variation in the leaf content of phenols of A. unedo, with the lowest values found in spring and the highest in autumn and/or winter. Leaf ontogenetic development and/or a possible effect of low temperatures in autumn/winter may account for such findings. Regardless of the watering regime and the sampling date, plant exposure to UV-B radiation decreased the total flavanol content of leaves, while it increased the leaf content in quercitrin (the most abundant quercetin derivative identified). By contrast, UV-A radiation increased the leaf content of theogallin, a gallic acid derivative. Other phenolic compounds (two quercetin derivatives, one of them being avicularin, and one kaempferol derivative, juglanin), as well as the antioxidant activity of the leaves, showed different responses to UV radiation depending on the precipitation regime. Surprisingly, reduced rainfall significantly decreased the total amount of quantified quercetin derivatives as well as the DPPH scavenging activity in A. unedo leaves. To conclude, present findings indicate that leaves of A. unedo can be a good source of antioxidants throughout the year, but especially in autumn and winter.

La abstención en las grandes ciudades, Madrid y Barcelona

El articulo analiza la evolucion de la participacion electoral en las areas metropolitanas de Madrid y Barcelona. Tras la descripcion de los cambios y la distribucion local de la abstencion se intenta apuntar algunas hipotesis explicativas a partir de tecnicas de regresion multiple. Se utilizan diversas variables agregadas (nivel de estudios, clase social, etc...) Entre las que el efecto desmovilizador del paro y de la inmigracion reciente y el incremento de la participacion alli donde hay mas asociaciones aparecen como las conclusiones mas significativas.

El reencuentro con el lugar : nuevas ruralidades, nuevos paisajes y cambio de paradigma

Estamos asistiendo a un reencuentro con el lugar a traves de nuevas e imaginativas formulas, como resultado de un cambio de paradigma liderado por una sociedad civil que entiende la accion politica de otra manera. Una sociedad civil que no tiene ningun problema en reconocer la importancia que tiene vincular las emociones a los lugares, a los paisajes y, en general, a la gestion del espacio publico. Emergen en el mundo rural nuevos proyectos y actitudes, nuevos valores, nuevas formas de organizacion social que, en algunos casos, surgen casi de la nada y, en otros, se han reforzado precisamente gracias a la hecatombe economica, social y cultural provocada por la tan manida crisis economica.