Untersuchungen zu Interaktionen zwischen bioelektrischen Signalen, Zytoskelettelementen, Zellpolarität und Gewebearchitektur im Ovar von Drosophila Melanogaster

  • Investigations on interactions between bioelectric signals, cytoskeletal elements, cell polarity and tissue architecture in the ovary of Drosophila melanogaster

Weiß, Isabel; Bohrmann, Johannes (Thesis advisor); Pradel, Gabriele (Thesis advisor)

Aachen (2020)
Dissertation / PhD Thesis

Dissertation, RWTH Aachen University, 2020


Bioelectric properties of cells play a role during development and regeneration of organisms as well as in a variety of human diseases. Gradual changes of bioelectric properties, such as membrane potential (Vmem), intracellular pH (pHi), ion concentrations or extracellular currents, serve as signals for the spatial and temporal regulation of morphogenetic processes. In the present study, bioelectric gradients, their formation and their influence on the cytoskeleton during oogenesis of Drosophila melanogaster are described. The fluorescent pH-indicator 5-CFDA,AM and the potentiometric dye DiBAC4(3) were used to analyse pHi- and Vmem-gradients, respectively. Basal microfilaments (bMF) and microtubules (MT) in the follicle-cell epithelium (FCE) were examined using fluorescence-labelled phalloidin and an antiserum against α-tubulin. For the analysis of the FCE-specific cytoskeleton in living follicles, the Gal4-UAS system was used (Lifeact-GFP and αTub84B-GFP). Stage-specific pHi- and Vmem-gradients, which are based on asymmetric distribution and activity patterns of ion-transport mechanisms, were investigated during stages S8 to S12. Furthermore, stage-specific bMF- and MT-patterns and their spatial and temporal correlations with pHi- and Vmem-gradients, respectively, were detected. Inhibitors were used to investigate the contributions of relevant ion-transport mechanisms to the regulation of pHi and Vmem as well as to the establishment of the gradients in the FCE: Na+/H+-antiporters and Na+-channels, V-ATPases, ATP-sensitive K+-channels, voltage-dependent L-type Ca2+-channels, Cl--channels and Na+/K+/2Cl--cotransporters. The use of these inhibitors led to changes of pHi and Vmem as well as of their gradients in the FCE. In addition, modifications of the cytoskeletal organization were observed, which correspond to changes occurring during development. Thus, pHi- and Vmem-changes caused by the use of inhibitors are able to simulate naturally occurring bioelectric modifications in the FCE. In addition, bioelectric modifications led to changes in the cytoskeletal organisation as observed during development of the FCE. Insights gained in this study contribute to a better understanding of the cause and meaning of bioelectric signals during development.