Das „Sandwich-Prinzip“ – Einführung in Lerner zentrierte Lehr-Lernmethoden in der Medizin

Lernen ist ein hochindividueller Prozess, der von zahlreichen Faktoren, wie Vorwissen, Aufmerksamkeit, Lerninteresse und Motivation abhängt. Effizientes Lernen erscheint deshalb nur durch Ermöglichung individueller Lernphasen im Unterricht erreichbar. Die Sandwicharchitektur von Lehrveranstaltungen stellt ein übergeordnetes Prinzip dar, das durch Einsatz verschiedenster didaktischer Methoden kollektive und individuelle Lernphasen integriert und so effiziente Lernprozesse unterstützt

microRNAs and the evolution of complex multicellularity:Identification of a large, diverse complement of microRNAs in the brown alga Ectocarpus

There is currently convincing evidence that microRNAs have evolved independently in at least six different eukaryotic lineages: animals, land plants, chlorophyte green algae, demosponges, slime molds and brown algae. MicroRNAs from different lineages are not homologous but some structural features are strongly conserved across the eukaryotic tree allowing the application of stringent criteria to identify novel microRNA loci. A large set of 63 microRNA families was identified in the brown alga Ectocarpus based on mapping of RNA-seq data and nine microRNAs were confirmed by northern blotting. The Ectocarpus microRNAs are highly diverse at the sequence level with few multi-gene families, and do not tend to occur in clusters but exhibit some highly conserved structural features such as the presence of a uracil at the first residue. No homologues of Ectocarpus microRNAs were found in other stramenopile genomes indicating that they emerged late in stramenopile evolution and are perhaps specific to the brown algae. The large number of microRNA loci in Ectocarpus is consistent with the developmental complexity of many brown algal species and supports a proposed link between the emergence and expansion of microRNA regulatory systems and the evolution of complex multicellularity

Arctic marine phytobenthos of northern Baffin Island

This project was supported by SAMS and NFSD core funding (Oceans 2025 WP 4.5 from the UK Natural Environment Research Council), the European Commission (ASSEMBLE, grant agreement no. 227799), and the TOTAL Foundation (Paris; Project “Macroalgal and oomycete benthic diversity in the Canadian Marine Arctic”). This work also received funding from the MASTS pooling initiative (The Marine Alliance for Science and Technology for Scotland) and their support is gratefully acknowledged. MASTS is funded by the Scottish Funding Council (grant reference HR09011) and contributing institutions. We also would like to thank Laura Grenville-Briggs (KTH, Stockholm) for help with bioinformatics analyses as well as Cindy Grant and Philippe Archambault (University of Quebec, Rimouski) for help with preparing the map of the study area (Fig. 1).Peer reviewedPublisher PD

A molecular insight into algal-oomycete warfare : cDNA analysis of Ectocarpus siliculosus infected with the basal oomycete Eurychasma dicksonii

Peer reviewedPublisher PD

psiCLIP reveals dynamic RNA binding by DEAH-box helicases before and after exon ligation

RNA helicases remodel the spliceosome to enable pre-mRNA splicing, but their binding and mechanism of action remain poorly understood. To define helicase-RNA contacts in specific spliceosomal states, we develop purified spliceosome iCLIP (psiCLIP), which reveals dynamic helicase-RNA contacts during splicing catalysis. The helicase Prp16 binds along the entire available single-stranded RNA region between the branchpoint and 3\u27-splice site, while Prp22 binds diffusely downstream of the branchpoint before exon ligation, but then switches to more narrow binding in the downstream exon after exon ligation, arguing against a mechanism of processive translocation. Depletion of the exon-ligation factor Prp18 destabilizes Prp22 binding to the pre-mRNA, suggesting that proofreading by Prp22 may sense the stability of the spliceosome during exon ligation. Thus, psiCLIP complements structural studies by providing key insights into the binding and proofreading activity of spliceosomal RNA helicases

Vertical Distribution of Epibenthic Freshwater Cyanobacterial Synechococcus spp. Strains Depends on Their Ability for Photoprotection

Epibenthic cyanobacteria often grow in environments where the fluctuation of light intensity and quality is extreme and frequent. Different strategies have been developed to cope with this problem depending on the distribution of cyanobacteria in the water column. and either constant or enhanced levels of carotenoids were assayed in phycocyanin-rich strains collected from 1.0 and 0.5 m water depths. Protein analysis revealed that while the amount of biliproteins remained constant in all strains during light stress and recovery, the amount of D1 protein from photosystem II reaction centre was strongly reduced under light stress conditions in strains from 7.0 m and 1.0 m water depth, but not in strains collected from 0.5 m depth. spp. strains, depending on their genetically fixed mechanisms for photoprotection

Molecular biology of the Ectocarpus / Eurychasma pathosystem

Ectocarpus siliculosus is commonly challenged by the intracellular oomycete pathogen Eurychasma dicksonii and unlike most other pathogens affecting algae, it is available in a laboratory-controlled pathosystem.  In the context of this PhD project, the molecular processes of algal response to pathogen infection has for the first time been studied on a pathosystem using genome-enabled approaches. The proteomic investigation of the compatible (disease-causing) interaction between E. siliculosus and Eu. dicksonii via comparative two-dimensional electrophoresis elucidated 21 differentially expressed proteins. A number of proteins, identified in this course, have been associated with various stress responses (e.g. heat shock proteins, superoxide dismutases) including defence response in previous studies on macroalgae.  Most important, some  results of this study uncovered molecular aspects of the host response to biotic stress which have not been documented with elicitor-based studies so far, stressing the biological value of this pathosystem. The identification of a Eurychasma-resistant Ectocarpus strain via a qPCR assay, specifically developed for this pathosystem, will allow future applications of the proteomic approach in the investigation of the incompatible (resistant) interaction. Furthermore, in-silico analysis of the E. siliculosus genome identified homologues of plant defence-related genes, coding for so-called pathogenesis-related (PR) proteins.  Taken together, these results open new routes for the understanding of algal host pathogen interactions.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Gene silencing in Fucus embryos: developmental consequences of RNAi-mediated cytoskeletal disruption

Brown algae (Phaeophyceae) are an important algal class that play a range of key ecological roles. They are often important components of rocky shore communities. A number of members of the Fucales and Ectocarpales have provided models for the study of multicellular evolution, reproductive biology and polarized development. Indeed the fucoid algae exhibit the unusual feature of inducible embryo polarization, allowing many classical studies of polarity induction. The potential of further studies of brown algae in these important areas has been increasingly hindered by the absence of tools for manipulation of gene expression that would facilitate further mechanistic analysis and gene function studies at a molecular level. The aim of this study was to establish a method that would allow the analysis of gene function through RNAi-mediated gene knockdown. We show that injection of double-stranded RNA (dsRNA) corresponding to an ?-tubulin gene into Fucus serratus Linnaeus zygotes induces the loss of a large proportion of the microtubule cytoskeleton, leading to growth arrest and disruption of cell division. Injection of dsRNA targeting ?-actin led to reduced rhizoid growth, enlarged cells and the failure to develop apical hair cells. The silencing effect on actin expression was maintained for 3 months. These results indicate that the Fucus embryo possesses a functional RNA interference system that can be exploited to investigate gene function during embryogenesis