Phenylpropanoids, particularly flavonoids have been recently suggested as playing primary antioxidant functions in the responses of plants to a wide range of abiotic stresses. Furthermore, flavonoids are effective endogenous regulators of auxin movement, thus behaving as developmental regulators. Flavonoids are capable of controlling the development of individual organs and the whole-plant; and, hence, to contribute to stress-induced morphogenic responses of plants. The significance of flavonoids as scavengers of reactive oxygen species (ROS) in humans has been recently questioned, based on the observation that the flavonoid concentration in plasma and most tissues is too low to effectively reduce ROS. Instead, flavonoids may play key roles as signaling molecules in mammals, through their ability to interact with a wide range of protein kinases, including mitogen-activated protein kinases (MAPK), that supersede key steps of cell growth and differentiation. Here we discuss about the relative significance of flavonoids as reducing agents and signaling molecules in plants and humans. We show that structural features conferring ROS-scavenger ability to flavonoids are also required to effectively control developmental processes in eukaryotic cells.

There is a growing body of evidence that flavonoids do not primarily function as UV-B screening pigments in photoprotection. Recent findings support the idea that excess light stress, irrespective of the relative proportions of the solar wavebands reaching the leaf surface, upregulates the biosynthesis of dihydroxy B-ring-substituted flavonoid glycosides, as a consequence of and aimed at countering the generation of ROS. Intriguingly, the very conditions that lead to the inactivation of antioxidant enzymes can also upregulate the biosynthesis of antioxidant flavonoids, which suggests flavonoids constituting a secondary ROS-scavenging system in plants exposed to severe/prolonged stress conditions. H 2 O 2 may diffuse out of the chloroplast at considerable rates and be transported to the vacuole, the storing site for flavonoids, by tonoplast intrinsic proteins, under severe excess light conditions. We suggest that the unanticipated key role of the vacuole in the ROS homeostasis might be mediated by flavonoids.The ancient and widespread flavonol metabolism has been widely reported to be mostly involved in the response mechanisms of plants to a wide range of stressful conditions.1 The loss of mycosporin-like aminoacid (MAA) in favor of flavonol metabolism is a strong evidence that flavonoids did not likely serve a primary UV-B screening function during the evolution of early land plants. 2,3 In fact (1) MAA are excellent UV-B absorbers and flavonols are less effective UV-B attenuators with respect

In 2008, a new term emerged in the already crowded e-learning landscape: MOOC, or massive open online course. Lifelong learners can now use various tools to build and manage their own learning networks, and MOOCs may provide opportunities to test such networks. This paper focuses on the technological aspects of one MOOC, the Connectivism and Connective Knowledge (CCK08) course, in order to investigate lifelong learners" attitudes towards learning network technologies. The research framework is represented by three perspectives: (a) lifelong learning in relation to open education, with a focus on the effective use of learning tools; (b) the more recent personal knowledge management (PKM) skills approach; and (c) the usability of web-based learning tools.Findings from a survey of CCK08 participants show that the course attracted adult, informal learners, who were not concerned about course completion. Time constraints, language barriers, and ICT skills affected the participants" choice of tools; for example, learners favoured the passive, time-saving mailing list over interactive, time-consuming discussions forums. Some recommendations for future MOOCs include highlighting the purpose of the tools (e.g., skillbuilding) and stating clearly that the learners can choose their preferred tools. Further research on sustainability and facilitator workload should be conducted to determine the cost and effectiveness of MOOCs. Investigation is also necessary to understand MOOC participant profiles as they relate to course outcomes and retention and whether terms such as course and attrition are appropriate in this context.

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Resumen. El propósito del artículo es mostrar la ruta metodológica seguida para desarrollar un cuestionario para estimar las habilidades digitales con propósito educativo que tienen los estudiantes de una universidad pública mexicana. Se describe el desarrollo de un cuestionario basado en cuatro dimensiones: manejo de información, de comunicación, de organización y de tecnología portátil. Se recurre a la consulta de expertos para la delimitación de los factores, la elaboración de los reactivos y la estimación de un indicador de univocidad. Se aplica un análisis preliminar basado en modelado estructural de ecuaciones para obtener evidencias de validez de la escala desarrollada. El cuestionario se aplicó al azar a una muestra de 350 estudiantes. Se propuso un modelo conceptual para el constructo de habilidad digital, el cual tuvo la congruencia esperada entre las variables observadas y la estructura propuesta. Tras una primera aplicación se obtuvieron valores aceptables en tres de los índices de bondad de ajuste (RMSEA, GFI y AGFI), con excepción de Chi-cuadrada y se detectaron posibilidades de adecuar la escala con base en los índices de modificación derivados del programa AMOS. La información obtenida permitirá mejorar la escala propuesta. Determinar las habilidades digitales de los estudiantes es un punto de interés actual en la búsqueda de la innovación y eficiencia de las actividades educativas. Palabras clave: habilidades de información; tratamiento de información; educación tecnológica; análisis estadístico.[en] Development of a questionnaire to estimate undergraduate digital skills Abstract. The purpose of this article is to show the methodological route carried out to develop a questionnaire to estimate the educational digital skills of students of a Mexican public university as well as to show evidence of construct validity through structural equation modeling. The development of a questionnaire based on four dimensions is described: management of information, communication, organization and portable technology. We draw on expert consultation for the delimitation of the factors, the development of reagents and the estimation of an indicator of _____________