Ground level isoprenoid exchanges associated with Pinus pinea trees in a Mediterranean turf

The emissions of isoprenoids, a kind of biogenic volatile organic compounds (BVOCs), from soils is not well characterized. We quantified the exchange of isoprenoids between soil with litter and atmosphere along a horizontal gradient from the trunks of the trees, in a Mediterranean Pinus pinea plantation with dry and green needle litter to open herbaceous turf during mornings at mid-summer. Further, potential associated drivers were identified. Isoprenoid emissions were greatest and most diverse, and also can be roughly estimated by litter dry weight near the trunk, where the needle litter was denser. The composition of emitted isoprenoid by needle litter was different than the composition previously described for green needles. Low exchange rates of isoprenoids were recorded in open turf. Isoprenoid exchange rates were correlated positively with soil temperature and negatively with soil moisture. Given the variations in ground emissions with soil, vegetation, microorganisms, and associated interactions, we recommend widespread extensive spatio-temporal analysis of ground level BVOC exchanges in the different ecosystem types

Bidirectional interaction between phyllospheric microbiotas and plant volatile emissions

Due to their antimicrobial effects and their potential role as carbon sources, plant volatile organic compound (VOC) emissions play significant roles in determining the characteristics of the microbial communities that can establish on plant surfaces. Furthermore, epiphytic microorganisms, including bacteria and fungi, can affect plant VOC emissions in different ways: by producing and emitting their own VOCs, which are added to and mixed with the plant VOC blend; by affecting plant physiology and modifying the production and emission of VOCs; and by metabolizing the VOCs emitted by the plant. The study of the interactions between plant VOC emissions and phyllospheric microbiotas is thus of great interest and deserves more attention

L'alzina podria perdre la seva hegemonia en el bosc mediterrani a causa del canvi climàtic

Les baixes temperatures de l'hivern i la baixa disponibilitat d'aigua són els dos factors principals que poden inhibir o danyar l'aparell fotosintètic de les espècies mediterrànies. Amb l'augment de les temperatures i la disminució de la disponibilitat d'aigua associades al canvi climàtic, hi ha un seguit d'espècies arbustives, com el fals aladern, que podrien competir amb avantatge amb l'alzina, l'actual espècie dominant dels boscos mediterranis.Las bajas temperaturas invernales y la baja disponibilidad de agua son los dos factores principales que pueden inhibir o dañar el aparato fotosintético de las especies mediterráneas. Con el aumento de las temperaturas y la disminución de la disponibilidad de agua asociadas al cambio climático, hay algunas especies arbustivas, como el labiérnago negro, que podrían competir ventajosamente con la encina, la actual especie dominante de los bosques mediterráneos

β-Ocimene, a key floral and foliar volatile involved in multiple interactions between plants and other organisms

β-Ocimene is a very common plant volatile released in important amounts from the leaves and flowers of many plant species. This acyclic monoterpene can play several biological functions in plants, by potentially affecting floral visitors and also by mediating defensive responses to herbivory. The ubiquity and high relative abundance of β-ocimene in the floral scents of species from most plant families and from different pollination syndromes (ranging from generalism to specialism) strongly suggest that this terpenoid may play an important role in the attraction of pollinators to flowers. We compiled abundant evidence from published studies that supports β-ocimene as a generalist attractant of a wide spectrum of pollinators. We found no studies testing behavioural responses of pollinators to β-ocimene, that could directly demonstrate or deny the function of β-ocimene in pollinator attraction; but several case studies support that the emissions of β-ocimene in flowers of different species follow marked temporal and spatial patterns of emission, which are typical from floral volatile organic compound (VOC) emissions that are involved in pollinator attraction. Furthermore, important β-ocimene emissions are induced from vegetative plant tissues after herbivory in many species, which have relevant functions in the establishment of tritrophic interactions. We thus conclude that β-ocimene is a key plant volatile with multiple relevant functions in plants, depending on the organ and the time of emission. Experimental behavioural studies on pure β-ocimene conducted with pollinating insects will be necessary to prove the assumptions made here

Students mediators. The assumption of the role

[ES] Existen numerosos estudios relacionados con el proceso de implantación y funcionamiento de la mediación escolar pero es difícil encontrar literatura relacionada con las condiciones que influyen en la identificación del alumnado mediador con su rol. El objetivo del estudio es identificar los aspectos clave que intervienen en el proceso de formación del rol del alumnado mediador (tercero y cuarto de Educación Secundaria Obligatoria). Al final del artículo se presenta un decálogo dirigido a la coordinación de mediación, en este sentido. Utilizando el método de Estudio de Casos Múltiples (cinco centros de secundaria obligatoria de Cataluña), partiendo de la idea de que los factores que influyen en la identificación con el rol mediador son la autopercepción, la formación, la experiencia en mediación, el apoyo de los diferentes agentes y la organización del servicio. Se administra un cuestionario a todos los alumnos mediadores de los cinco centros y a los coordinadores de mediación y, se realiza un focus group con 10 alumnos mediadores para profundizar y contrastar los resultados iniciales.Los resultados apuntan que el alumnado se siente mediador y desarrolla un sentimiento de pertinencia cuando pasan a formar parte del servicio. Se sienten seguros cuando compañeros y profesores reconocen su función mediadora. Destacan la figura del coordinador como la más importante en el proceso de identificación y, el funcionamiento del propio servicio de mediación. Las conclusiones también presentan el decálogo de aspectos que deben darse en los centros de educación secundaria obligatoria para potenciar la asunción del rol del alumnado mediador.[EN] There are many studies about the mediation and the implementation process of mediations, but is hard to find literature about the conditions that have influence in the mediator’s identification with his role. The objective of this study is identify the key conditions that are involved in the formation process of the mediator’s role on the students of 3rd and 4th of Secondary Education. At the conclusions of this article a Decalogue is presented directed to the Coordinators of mediators, in this sense. The multiple case methods are used in this study (in the sample had participated 5 Secondary Schools from Catalonia). At the beginning of the study the factors that have influence in the mediator’s identification with the mediator’s role are the auto-perception, the training, the mediation experience, the support of different agents and the service’s organization. To collect the information, a questionnaire was administered to all the Mediators Students and Coordinators of the mediation service of the five centers. Finally one focus group with 10 Mediators students was done to deepen and contrast on the beginning results. The finally results suggest that the student feels himself mediator and develop a sense of belonging when he receives training and becomes part of the service. They feel safe and comfortable when their colleagues and teachers recognize to them their role like mediators. The students highlight the figure of the Service Coordinator and the functioning of the mediation service like the most important factors in the process of identifying themselves like mediators. At the conclusions is presented a conditions Decalogue that should be in the Secondary School to boost the assumption of the role of student mediator.Mozo Llusià, M.; Armengol Asparó, MC. (2019). Los estudiantes como mediadores escolares. La asunción del rol. Revista sobre la infancia y la adolescencia. (17):1-20. https://doi.org/10.4995/reinad.2019.11403SWORD1201

Iridoids and other Mmnoterpenes in the Alzheimer’s Brain: Recent development and future prospects

Iridoids are a class of monoterpenoid compounds constructed from 10-carbon skeleton of isoprene building units. These compounds in their aglycones and glycosylated forms exist in nature to contribute to mechanisms related to plant defenses and diverse plant-animal interactions. Recent studies have also shown that iridoids and other structurally related monoterpenes display a vast array of pharmacological effects that make them potential modulators of the Alzheimer’s disease (AD). This review critically evaluates the therapeutic potential of these natural products by assessing key in vitro and in vivo data published in the scientific literature. Mechanistic approach of scrutiny addressing their effects in the Alzheimer’s brain including the τ-protein phosphorylation signaling, amyloid beta (Aβ) formation, aggregation, toxicity and clearance along with various effects from antioxidant to antiinflammatory mechanisms are discussed. The drug likeness of these compounds and future prospects to consider in their development as potential leads are addressed

Photosynthesis, stomatal conductance and terpene emission response to water availability in dry and mesic Mediterranean forests

Water stress results in a reduction of the metabolism of plants and in a reorganization of their use of resources geared to survival. In the Mediterranean region, periods of drought accompanied by high temperatures and high irradiance occur in summer. Plants have developed various mechanisms to survive in these conditions by resisting, tolerating or preventing stress. We used three typical Mediterranean tree species in Israel, Pinus halepensis L., Quercus calliprinos and Quercus ithaburensis Webb, as models for studying some of these adaptive mechanisms. We measured their photosynthetic rates (A), stomatal conductance (g s), and terpene emission rates during spring and summer in a geophysical gradient from extremely dry to mesic from Yatir (south, arid) to Birya (north, moist) with intermediate conditions in Solelim. A and g s of P. halepensis were threefold higher in Birya than in Yatir where they remained very low both seasons. Quercus species presented 2-3-fold higher A and g s but with much more variability between seasons, especially for Q. ithaburensis with A and g s that decreased 10-30-fold from spring to summer. Terpene emission rates for pine were not different regionally in spring but they were 5-8-fold higher in Birya than in Yatir in summer (P < 0.05). Higher emissions were also observed in Solelim for the drought resistant Q. ithaburensis (P < 0.001) but not for Q. calliprinos. α-Pinene followed by limonene and 3-carene were the dominant terpenes. Warmer summer conditions result in increased Terpene emission rates except under severe drought, in which case they strongly decreas