Mechanik und Dynamik biologischer Modellsysteme am Beispiel aktingefüllter Vesikel und synchroner Zellmigration von Dictyostelium discoideum

Mechanics and dynamics of biological model systems examining actin-filled vesicles and synchronous cell migration of Dictyostelium discoideum

by Edith Elisabeth Schäfer
Doctoral thesis
Date of Examination:2012-09-19
Date of issue:2013-02-06
Advisor:Prof. Dr. Andreas Janshoff
Referee:Prof. Dr. Andreas Janshoff
Referee:Prof. Dr. Sarah Köster
Persistent Address: http://dx.doi.org/10.53846/goediss-3574

 

 

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Abstract

English

This thesis analyzes the dynamics of cell contacts of synchronic cells and the mechanical characteristics of the plasma membrane on the basis of two different model systems. The first model system consisting of the amoebae Dictyostelium discoideum deals with periodic changes of the cells during the chemotaxis in the aggregation phase. By electric cell-substrate impedance sensing (ECIS) in conjunction with optical microscopy periodic changes of cell-cell as well as cell-substrate contacts could be detected. Quartz crystal microbalance with dissipation (D-QCM) analyses and time-resolved total internal reflection fluorescence (TIRF) microscope videos confirm that the detected impedance oscillations during the collective chemotaxis of the cells are induced by cell-substrate distance changes. Important influences on the formation of cellular adhesion have the plasma membrane and the associated actin cortex underneath the cell membrane. With a second model system consisting of giant unilamellar lipid vesicles the mechanical properties of artificial membranes without and with an actin cortex were analyzed. Therefore, a new measurement method was developed to compress vesicles with a tipless cantilever between two parallel plates. Force-compression curves display a nonlinear response that allows to determine static tension and the area compressibility modulus by computing the contour of the vesicle as a function of compression depth.
Keywords: Dictyostelium discoideum; oscillation; collective migration; area compressibility modulus; membrane properties; actin-filled vesicles; vesicle compression

Other Languages

Diese Arbeit beschäftigt sich mit zwei verschiedenen Modellsystemen, die Aufschluss über die Mechanik und die Dynamik von zellulären Systemen geben sollen. Zum Einsatz kommt zum einen der Modellorganismus Dictyostelium discoideum, dessen kollektives Migrationsverhalten analysiert wird und zum anderen wird die Mechanik von aktingefüllten Riesenvesikeln als artifizielles Modellsystem etabliert.
Schlagwörter: Dictyostelium discoideum; Oszillation; kollektive Migration; Flächenkompressionsmodul; Membraneigenschaften; aktin gefüllte Vesikel; Vesikelkompression
 
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