evolution, structure and function of metazoan splicing factor PRPF39

In the yeast U1 snRNP the Prp39/Prp42 heterodimer is essential for early steps of spliceosome assembly. In metazoans no Prp42 ortholog exists, raising the question how the heterodimer is functionally substituted. Here we present the crystal structure of murine PRPF39, which forms a homodimer. Structure-guided point mutations disrupt dimer formation and inhibit splicing, manifesting the homodimer as functional unit. PRPF39 expression is controlled by NMD-inducing alternative splicing in mice and human, suggesting a role in adapting splicing efficiency to cell type specific requirements. A phylogenetic analysis reveals coevolution of shortened U1 snRNA and the absence of Prp42, which correlates with overall splicing complexity in different fungi. While current models correlate the diversity of spliceosomal proteins with splicing complexity, our study highlights a contrary case. We find that organisms with higher splicing complexity have substituted the Prp39/Prp42 heterodimer with a PRPF39 homodimer

Bandwidth renormalization due to the intersite Coulomb interaction

The theory of correlated electrons is currently moving beyond the paradigmatic Hubbard $U$, towards the investigation of intersite Coulomb interactions. Recent investigations have revealed that these interactions are relevant for the quantitative description of realistic materials. Physically, intersite interactions are responsible for two rather different effects: screening and bandwidth renormalization. We use a variational principle to disentangle the roles of these two processes and study how appropriate the recently proposed Fock treatment of intersite interactions is in correlated systems. The magnitude of this effect in graphene is calculated based on cRPA values of the intersite interaction. We also observe that the most interesting charge fluctuation phenomena actually occur at elevated temperatures, substantially higher than studied in previous investigations.Comment: New appendix on benzen

Ecomat und Dammkultur – Alternative Bodenbearbeitungssysteme im Ökologischen Landbau – Erste Ergebnisse aus einem Exaktversuch

In the interdisciplinary research project a field experiment of alternative tillage systems in organic farming was installed. Ridge till system from Turiel-Major and Ecomat-system from Kverneland will be compared with conventional ploughing system. Within the project, located on the experimental farm of the University of Kassel, regular yearly workshops are led. Due to the regular contact with farmers, advisers, developers and scientists knowledge of practice will be carried into scientific research, the transfer of knowledge will be carried on. The change to the Ecomat-system is simple. Take notice that after very shallow till-age, like stubble cultivation (short stubble) or turning grass-clover, the following tillage has to be done a few cm deeper. In the year of implementing the Ecomat-system there were no decreases in yields. The mineralization of Nitrogen was the same as in the ploughing system. When changing to the ridge till system the width of the dams (90 cm) must fit to the track width, planting and harvesting equipment. After stubble cultivation in the ridge till system mineralization of N increased. This N was taken up by the catch crop. Leaching of N is not expected. Even in the first year after changing the tillage systems the alternative systems Eco-mat and ridge till showed higher saturated hydraulic conductivity than the conventional ploughing system. This leads to much lower susceptibility of soil erosion when using these soil layer conservation systems

Ermittlung der Futterqualität verschiedener Wintererbsengenotypen in Rein- und Gemengesaat zur Nutzung als nachwachsender Rohstoff, als Grünfutter und als Druschfrucht

Normalblättrige Wintererbsen sind in Reinsaat eine rohproteinreiche Winterzwischenfrucht für die Nutzung als Grünfutter oder als nachwachsender Rohstoff zur Energiegewinnung im Rahmen von Zweikulturnutzungssystemen. Zum Korndrusch im Gemengeanbau stellen sie bei mindestens vergleichbaren Kornerträgen und Qualitäten eine Alternative zu Sommererbsen dar. Dabei können Anbauprobleme von Sommererbsen besonders hinsichtlich der Unkrautregulierung reduziert werden