<> "The repository administrator has not yet configured an RDF license."^^ . <> . . "Investigation of Molecular Interactions in Cytoskeletal Systems with Holographic Optical Tweezers"^^ . "Optical tweezers are a versatile tool to apply and measure forces in the piconewton range on microscopic ob jects that are held by optical forces in a focussed laser beam. We employed holographic optical tweezers (HOT) to create extended force sensor arrays, consisting of multiple trapped particles that were controlled and probed individually. The combination of high-speed video microscopy with fluorescence imaging allowed the visualization of labeled protein structures in parallel with the tracking of multiple trapped particles for force measurements. Using this setup, we could perform quantitative force measurements on biological samples with HOT for the first time. To obtain reliable force measurements, calibration methods based on power spectra analysis were adapted for holographic optical tweezers. In microfluidic environments, biomimetic structures of the cellular cytoskeleton could be reconstituted between optically trapped microspheres. Flow cells and fluidic control, developed in this work allowed the exchange of solutions in the system and thus, the complete control of the chemical environment without generating forces that would affect the trapped particles. This provided the possibility to measure dynamic processes such as the contractility of two-dimensional cross-linked actin networks in the microfluidic flow cell. A network of actin fibers between seven trapped particles was created and the forces during cross-linking were obtained. To investigate bundling processes between filaments, a method has been established using dynamic HOT to manipulate zipper-like structures between trapped particles actively. Analysis of particle trajectories during zipping of filaments allowed the determination of binding energies between filaments. Unbundling forces between actin filaments were measured on trapped spheres during the active process of unzipping. Additionally, this system was transferred to actin networks on PDMS micropillar substrates to improve feasibility. In combination with the optical trap, this allowed for the investigation of unbundling forces for alpha-actinin as well as for magnesium ions as cross-linkers. In a different set of experiments, the adhesion process of the Malaria causing parasite Plasmodium was investigated. Adhesion and locomotion of the sporozoites is crucial for the infectivity of the parasite. A methodology for laser tweezer experiments with Plasmodium sporozoites was developed. Using optical tweezers, the formation of adhesion sites in the presence of actin disrupting drugs was probed and compared to knock-out parasite strains. We found the second step of sporozoite adhesion sequence to be significantly dependend on actin and a specific transmembrane protein named TRAP."^^ . "2009" . . . . . . . . "Kai"^^ . "Uhrig"^^ . "Kai Uhrig"^^ . . . . . . "Investigation of Molecular Interactions in Cytoskeletal Systems with Holographic Optical Tweezers (PDF)"^^ . . . "dissertation.pdf"^^ . . . "Investigation of Molecular Interactions in Cytoskeletal Systems with Holographic Optical Tweezers (Other)"^^ . . . . . . "indexcodes.txt"^^ . . . "Investigation of Molecular Interactions in Cytoskeletal Systems with Holographic Optical Tweezers (Other)"^^ . . . . . . "lightbox.jpg"^^ . . . "Investigation of Molecular Interactions in Cytoskeletal Systems with Holographic Optical Tweezers (Other)"^^ . . . . . . "preview.jpg"^^ . . . "Investigation of Molecular Interactions in Cytoskeletal Systems with Holographic Optical Tweezers (Other)"^^ . . . . . . "medium.jpg"^^ . . . "Investigation of Molecular Interactions in Cytoskeletal Systems with Holographic Optical Tweezers (Other)"^^ . . . . . . "small.jpg"^^ . . "HTML Summary of #9587 \n\nInvestigation of Molecular Interactions in Cytoskeletal Systems with Holographic Optical Tweezers\n\n" . "text/html" . . . "540 Chemie"@de . "540 Chemistry and allied sciences"@en . .