Yearbook 2005

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Researchers in the 1980s believed Cecco del Caravaggio’s ‘Cupid at the Fountain’ to be ‘perhaps the most shameless painting ever to emerge from the time and artistic milieu [of Caravaggio]’. However, such an interpretation, derived solely from the supposed sexual disposition of the artist, cannot explain many details within the painting. In fact, the painting illustrates amor Dei, the desire for God. If one accepts this interpretation of the painting the composition as a whole unfolds as a highly complex reflection upon the possibilities and limitations of a realistic religious painting. more
Digilib is a software tool for the scholarly study of images via internet. Images can be zoomed and annotated in a persistent way. It was developed as open source software by the Berlin Max Planck Institute for the History of Science and the Bibliotheca Hertziana – Max Planck Institute for Art History in Rome in collaboration with the Institute for History and Philosophy of Science at Bern University. Digilib opens up new perspectives of scholarly research working on digital images. more
Our research focuses on the regulation of substrate specificity in the ubiquitin proteasome system, specifically on two modular protein complexes: the CBCVHL ubiquitin ligase with its substrate binding subunit, the von-Hippel-Lindau tumor suppressor protein, and the chaperone-like Cdc48 AAA ATPase with cofactors of the UBX protein family. UBX proteins bind to Cdc48 and thereby regulate the specificity of Cdc48 activity in various cellular processes. UBX proteins with a ubiquitin binding UBA domain recruit ubiquitylated substrates which are targeted via Cdc48 for proteasomal degradation. One such UBA/UBX protein, called Ubx2, plays a central role in endoplasmic reticulum (ER) associated protein degradation (ERAD). Biochemical studies of tumor associated mutants of the von-Hippel-Lindau tumor suppressor protein provide new insights in the complex genotype/phenotype relationship of the von-Hippel-Lindau disease. For instance, the extent of functional defects on the molecular level correlates with the patients´ risk of developing renal cell carcinomas. more
Coordinated growth and differentiation of specialized tissues during the development of higher eukaryotes requires precisely regulated communication between the multiple cell types of an organism. The same holds for the maintenance of all life functions of mature organisms. Defects in the cellular communication network cause multitudes of pathological phenomena such as cancer, diabetes and neurodegenerative diseases. The research program of the Department of Molecular Biology is focussed on the elucidation of such critical biological and pathophysiological processes. Main emphasis of the research efforts is on the investigation of signaling mechanisms in normal cells and degeneration of signaling pathways in cancer. more
Quantification of greenhouse gas exchange between surface and atmosphere on regional scales is crucial for process understanding, but also for verification of greenhouse gas budgets in the context of emission trading. The combination of regional modelling and airborne measurements allows a rigorous assessment of the methods used in the quantification of trace gas fluxes, both with respect to the measurement strategy (measurement network design), but also with respect to the modelling approach (atmospheric transport modelling, biospheric modelling). The long term goal is the optimal integration of measurements within the modelling systems, taking unavoidable representation errors into account quantitatively. This presents a precondition for estimating the uncertainties associated with trace gas budgets. more
Somatic Cells can be reprogrammed to pluripotency by fusion with embryonic stem cells. Factors involved in this process appear to be associated with the nucleus of pluripotent cells and give rise to reprogrammed, pluripotent cells from neuronal precursor as well as terminally differentiated cumulus cells. Their differentiation potential is unrestricted but these cells have a doubled chromosome set, which is addressed in current research projects of the MPI for Molecular Biomedicine in Münster. more
Phototaxis and photophobic responses of the green alga Chlamydomonas reinhardtii are mediated by microbial rhodopsins with the chromophore retinal. Sequence comparison with other microbial rhodopsins from archaea as the light-driven proton pump bacteriorhodopsin and the light-driven chloride pump halorhodopsin showed an overall homology of 15 to 20 % of those two algae chromoproteins. It is equally important that the N-terminal half approximately 300 of 712 and 737 amino acids, respectively, comprises seven hypothetical transmembrane helices as it is typical for rhodopsin-like proteins. Morover, several of the amino acids are conserved, which define the retinal binding site as well as the H+ -transporting pathway in bacteriorhodopsin. Recently, we demonstrated that two of these retinal-binding proteins from the eyespot of the alga, which we named channelrhodopsin-1 and -2 (ChR1 and ChR2), showed channel activity, directly activated by light when expressed in oocytes from Xenopus laevis or HEK 293 cells. ChR1 is selective for protons, whereas ChR2 is also conductive for monovalent and divalent cations. For both proteins the N-terminal hydrophobic half is sufficient to enable light-gated channel activity, demonstrating that the seven transmembrane helix motif represents a new class of ion channels. more
In the cerebral cortex information processing strongly relies on the connectivity between different areas. So far, investigations have concentrated on the role of feed-forward connections linking lower areas to higher order centers. However, there is also a dense network of feed-back connections which transmit signals back to the primary sensory areas. We have investigated the role of these connections using optical and electrophysiological recording techniques in combination with reversible deactivation methods and showed that feed-back connections exert a strong influence over the neuronal processes in early sensory areas. Moreover, we investigated how use-dependent cortical plasticity is related to different states of cortical processing and found that only in states of high frequency oscillatory activity, which are related to wakefulness and attention, an enhancement of the representations of repetitively experienced stimuli can be induced. more
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