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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
Dec. 17, 2009

Gradient Optical Traps

The powerful results in the molecular and cellular domain that are currently obtained using optical tweezers are leading to an increasing interest in this biophysical tool. Once calibrated, laser traps can be used to accurately measure the forces and displacements involved in many different molecular processes. Unfortunately, standard force detection techniques are not suitable for experiments inside living cells. more
Dec. 17, 2009

Protrusion Force Measurements with the SFM on Motile Cells

A fundamental step in cell migration is the advancement of the cell's leading edge. It is generally accepted that this motion is driven by actin polymerization against the plasma membrane but this has not been directly measured. more
Dec. 16, 2009

The “Walking” Mechanism of Kinesin-1 in 3D

Kinesin-1 is a molecular motor essential for cellular function. It transports components such as membrane-bound organelles and molecular complexes around a cell by travelling along microtubule filaments, which make up part of the cytoskeleton, while hydrolysing ATP. This motion is processive, in one direction only and is known to involve both of kinesin's two heads. Although extensively studied by a variety of techniques over many years, the mechanism these single-molecule motors use for this efficient motion on the nanoscale is not fully understood. more
FRET and Translocation in Cell-based Imaging
Dec. 14, 2009

FRET and Translocation in Cell-based Imaging

Microscopy in combination with fluorescence labeling techniques has enabled us to look at diverse biological processes. By tagging a protein of interest, we learn about its intracellular localization and dynamics. Fluorescence resonance energy transfer (FRET) sensors, which carry two fluorescent tags instead of one, a donor and an acceptor, are generated to obtain information about protein function. While the use of multiple labels is straightforward and common in high content imaging and screening, the use of multiple FRET sensors is more difficult. more
Dec. 14, 2009

Holographic Optical Tweezers

The actin cortex, a quasi two-dimensional network of actin, plays an important role in cell stability, motility and viscoelasticity. In vivo, its characteristic properties are controlled by various actinbinding proteins (ABPs), such as crosslinkers or ions. To investigate the influence of specific crosslinkers on the network's behaviour exclusively, we create and probe biomimetic models of the actin cortex. This is realized using microbeads trapped by holographic optical tweezers (HOTs) as scaffold for the actin filaments. more
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