Structure and assembly cues of Arabidopsis root-inhabiting bacterial communities and comparative genomics of selected Rhizobium members

The plant root defines the interface between a multicellular eukaryote and soil, one of the richest microbial ecosystems on earth. Soil bacteria are able to colonize the root surface and even multiply inside roots as benign endophytes. Some of these bacteria modulate plant growth and development, with implications ranging from enhanced nutrition to resistance against pathogens. In this study a high-resolution methodology based on pyrosequencing of the bacterial 16S rRNA marker gene was adopted to characterize and compare soil and root-inhabiting bacterial communities. Our results show that roots of Arabidopsis thaliana, grown in different natural soils under controlled environmental conditions, are preferentially colonized by Proteobacteria, Bacteroidetes and Actinobacteria, and each bacterial phylum is represented by a dominating class or family of bacteria. Soil type defines the composition of root-inhabiting bacterial communities whereas the host genotype modulates their profiles only to a limited extent. Furthermore, bacterial communities associated to wooden sticks, representing a metabolically inactive lignocellulosic matrix for bacterial colonization, were analyzed to deconvolute actively recruited from opportunistic root microbiota members. This comparison showed that plant cell wall features appear to provide a sufficient cue for the assembly of app. 40% of the Arabidopsis root microbiota. This root- and wood-shared sub-community was mainly composed by Betaproteobacteria. In contrast, specifically recruited members of the root-inhabiting bacteria, mostly Actinobacteria, depended on cues from metabolically active host cells, defining a root-specific sub-community. This culture-independent survey of the Arabidopsis root-associated bacteria was utilized to guide a targeted cultivation-based approach resulting in the isolation of members of both sub-communities of the Arabidopsis root-inhabiting bacterial microbiota. Several Rhizobium spp., which are either members of the shared or specific sub-communities, were isolated from Arabidopsis roots in pure culture and tested for plant growth promotion capabilities. Upon inoculation in a gnotobiotic system, Rhizobium spp. isolated from the specific sub-community increased shoot fresh weight of Arabidopsis, while a Rhizobium strain from the shared sub-community was not able to promote plant growth. Comparative whole-genome analysis of independent exemplars of the isolated Rhizobium spp. revealed differential gene enrichments among members of both sub-communities. Particularly, the amplification and divergence of transcription factor genes might represent a signature of differential habitat adaptation. This culture-based approach backed by a broad scale culture-independent survey sets the stage to advance from descriptive characterization of bacterial communities to testing the functional significance of plant-microbiota interactions

Measurement of media pedagogical competences of adult educators

Media pedagogical competence is critical for the modern-day adult educator. In the process of adult learning, both the use of digital media in the classroom and the transfer of knowledge in dealing with media are the basis for social participation and individual development that must be provided by teachers. However, at present little or no research has been conducted that assess media pedagogical competence of adult educators. Moreover, an instrument to measure media pedagogical competence was lacking. In order to redress these concerns, in the present paper an instrument for objectively measuring media pedagogical competence is designed and piloted with adult educators (n=622). The study provides the first results concerning objective measurement of adult educator media pedagogical competence. (DIPF/Orig.

Fit für die digitale (Lern-)Welt? Medienpädagogische Kompetenzanforderungen an Erwachsenenbildner/innen

Fit for the digital (learning) world? Media educational competence requirements for adult educators The development of digital media continuously provides new opportunities for developing teaching/learning processes. As a result, the media educational requirements for teachers to assess the relevant chances and risks and to use digital media effectively as a learning support, is growing. The article points out the demand for paying increased attention to this specific competence. It presents a media educational competence model for adult educators, which was developed on a theoretical and empirical basis.Auch wenn digitale Medien noch eher selten und rudimentär Anwendung in der Erwachsenenbildung finden, ist der Trend zur stärkeren Digitalisierung von Lehr-/Lernkontexten auch hier unübersehbar. Medienpädagogische Kompetenzen auf Seiten der Lehrenden sind Voraussetzung für einen sinnvollen Medieneinsatz in der Erwachsenenbildung. Deshalb ist es unumgänglich, sich mit den medienpädagogischen Kompetenzanforderungen auseinanderzusetzen, die an Erwachsenenbildnerinnen und -bildner gestellt werden. Im Projekt MEKWEP wurde ein auf die Erwachsenenbildung ausgerichtetes medienpädagogisches Kompetenzmodell entwickelt, das die Autorinnen und Autoren hier vorstellen

The glaciers climate change initiative: Methods for creating glacier area, elevation change and velocity products

Glaciers and their changes through time are increasingly obtained from a wide range of satellite sensors. Due to the often remote location of glaciers in inaccessible and high-mountain terrain, satellite observations frequently provide the only available measurements. Furthermore, satellite data provide observations of glacier character- istics that are difficult to monitor using ground-based measurements, thus complementing the latter. In the Glaciers_cci project of the European Space Agency (ESA), three of these characteristics are investigated in detail: glacier area, elevation change and surface velocity. We use (a) data from optical sensors to derive glacier outlines, (b) digital elevation models from at least two points in time, (c) repeat altimetry for determining elevation changes, and (d) data from repeat optical and microwave sensors for calculating surface velocity. For the latter, the two sensor types provide complementary information in terms of spatio-temporal coverage. While (c) and (d) can be generated mostly automatically, (a) and (b) require the intervention of an analyst. Largely based on the results of various round robin experiments (multi-analyst benchmark studies) for each of the products, we suggest and describe the most suitable algorithms for product creation and provide recommendations concerning their practical implementation and the required post-processing. For some of the products (area, velocity) post-processing can influence product quality more than the main-processing algorithm