Berlin 2018 – wissenschaftliches Programm

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BP: Fachverband Biologische Physik

BP 10: Postersession II

BP 10.44: Poster

Montag, 12. März 2018, 17:30–19:30, Poster C

Visualization of intracellular calcium levels in Dictyostelium discoideum with a genetically encoded reporter — •Manuel Frey, Sven Flemming, Serena Cucinotta, and Carsten Beta — Biological Physics, Universität Potsdam

Ca²⁺ is an important second messenger in eukaryotic cells and is crucial for several signaling pathways related to cellular functions such as chemotaxis and cell motility. In order to visualize Ca²⁺ in the social amoeba Dictyostelium discoideum, we expressed a genetically encoded GFP based Ca²⁺ reporter at the plasma membrane. This enabled us to monitor spatiotemporal changes in the intracellular Ca²⁺ levels. As expected, we could detect global increases in calcium levels after chemotactic stimulation with cyclic AMP. Mechanical stimulation of cells with a micropipette led to a local calcium response. Furthermore, we could detect short, focal increases of Ca²⁺ at the basal plasma membrane, which coincided with the appearance of F-actin foci at the same location. In cells exposed to continuous shear flow, we observed periodic oscillations of the intracellular Ca²⁺ levels. Interestingly, once excited these oscillations continued for several minutes even after the shear flow was stopped. In contrast, application of a short pulse of shear flow induced only single responses. Our results show that localized increases in Ca²⁺ can be visualized with our new reporter in live cell imaging experiments and revealed interesting oscillatory behavior under shear flow. Currently, we work on the co-expression of other reporters, which will provide more information on the biological function of this behavior and the related signaling pathways.