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Dec. 30, 2009

The Dynamic of Synthetic Proteo-nucleic Complexes

Synthetic proteo-nucleic structures (PDNA) encompassing a ss-DNA sequence covalently attached to a cytochrome b5-derived protein domain through a synthetic linker were designed. PDNAs can bind to natural or supported membranes through an histidine-tag-nickel-NTA modified phospholipids. Alternatively the structures can be attached, while keeping free lateral diffusion capabilities, by interaction of the protein his-tag with a substrate supported field of nickel ions. more
Dec. 29, 2009

Optical Tweezers

The propulsion of the leading edge of neuronal lamellipodia is a complex process in which the polymerization of actin filaments towards the cell membrane is a major component [1,2]. This process is at the origin of force generation in neurons. By using optical tweezers, we have characterized the dynamics by which lamellipodia of Dorsal Root Ganglia neurons exerted force on encountered obstacles such as silica beads. more
Dec. 28, 2009

AFM-studies on Solid Supported Lipid-bilayers with Bound Proteins

Proteins are involved in all processes which are necessary for living, e.g. they are responsible for growth and cleavage of cells, which makes them an interesting topic for science and medical application. Small GTPases, like Ras, are GTP-binding proteins involved in cellular processes, e.g. vesicle transport, cell cycles, nuclear import and signal transduction. GTPases act as molecular switches, which cycle between a GDP-bound inactive and a GTP-bound active state regulated through different factors. In oncogenic mutants of Ras this regulation is disturbed. more
Dec. 23, 2009

Determination of Physical Properties of a Single Peptide by AFM Experiments

By stretching a polymer in solution using single molecule techniques it is possible to infer about its physical properties. In particular, AFM stretching experiments allow for a full characterization of the elasto-mechanical properties of the sample under study, taking into account both statical and dynamical regimes [1]. In the presented work, single molecule AFM force spectroscopy experiments have been used to determine mechanical properties of a polymer obtained starting from the Exon 28 (Ex28) of the human elastin gene. more
Dec. 22, 2009

Multiple Facets of Neuronal Growth

A prerequisite for an understanding of the mechanisms of nerve regeneration and neuronal development is the understanding of the principles of force generation in growth cones - the mechanical and chemical sensor of a neuron. In our working group we try to approach this issue from a variety of different aspects, combining experimental and theoretical studies of actin networks, membrane fluctuations and focal adhesion sites. more
Dec. 21, 2009

Cell Adhesion on Micro-Nanostructured Surfaces

Many aspects of cellular adhesion to the surrounding, the extracellular matrix (ECM), are of great interest as they control and influence various fundamental cell actions such as motility, differentiation, proliferation and apoptosis and hence, even the function of an organism may depend on this complex and highly regulated process. more
Dec. 18, 2009

AFM Discriminates Between Cell Lines

We report for the first time the use of Atomic Force Microscopy (AFM) in discriminating between living normal human urothelial cells (HUC) and bladder tumour cells (MGH) on the basis of their ultrastructure and nanomechanical properties. AFM imaging revealed clear differences in the shapes and dimensions of MGH and HUC cells: MGH cells had the tendency to cluster and therefore they did not spread much compared to their normal counterparts. As a consequence, the dimensions of MGH cells were found to be smaller than those of normal HUCs. more
Dec. 18, 2009

Optical Tweezer Experiments

Optical trapping techniques have evolved to the point where quantitative force measurements on biological systems can be performed down into the femtonewton range. As resolution is constantly improving, the pinpointing and elimination of noise sources become increasingly important. Allan-variance analysis is ideally suited for this task; adjacent time series are recorded and the variations between observation intervals are calculated. more
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