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Intercellular communication and transport processes
during development

The ovary of Drosophila melanogaster is a popular model system for investigating numerous aspects of cell and developmental biology. During development of a stem cell into a mature egg almost every possible cellular process is involved. In the ovarian follicle (see figures), the oocyte (OOC) and 15 polyploid nurse cells (NC) form a syncytium by way of intercellular bridges (or ring canals, RC). This cell cluster is surrounded by a layer of somatic follicle cells (FC). The three cell types are known to interact in many ways during oogenesis. In particular, coordinated cooperation between germ-line and soma cells is required for the correct establishment of the embryonic body pattern, especially its spatial coordinates. Yet the routes for the intercellular exchange of information are only partly analysed. Our investigations concentrate on such communication and transport processes that occur via intercellular bridges, gap junctions, ion pumps and ion channels.

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Ovarian follicle of Drosophila

 

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Body patterns of the embryo and the adult fly

 


We are studying cytoplasmic transport processes between nurse cells and oocyte by means of diverse microscopic techniques, microinjections and inhibitors. From these studies we obtain information about the specific mechanisms that are involved in the cytoskeleton-dependent localization of cytoplasmic determinants playing key roles during the course of development.

 

Selected publications:

Bohrmann J, Cell Mol Life Sci 53:652-662, 1997.

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Fluorescent staining of microfilaments (white resp.
red) and nuclei (blue) in young ovarian follicles
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Via gap junctions, i. e. clusters of small membrane channels, intercellular communication takes place that can be stimulated or inhibited by a variety of treatments. By means of microinjections, antibodies and inhibitors we gain insight into the molecular basis and into the role that gap-junctional communication plays during the regulation of development.

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Communication between oocyte and follicle cells occurs via gap junctions: microinjected antibodies (C) inhibit the distribution of a fluorescent tracer (ip, injection pipette; sp, suction pipette;
bar, 100 µm)
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Morphogenetic movements depend on intercellular communication: blocking gap junctions (right) inhibits gastrulation (ventral view of the embryo, nuclear staining)

Selected publications:

Bohrmann J, Zimmermann J, BMC Dev Biol 8:111, 2008.

 


Using voltage- and ion-sensitive dyes or microelectrodes, bioelectric phenomena and ion-exchange processes can be detected during oogenesis. They are involved in various cellular processes like e. g. growth, cell migration, apoptosis, osmoregulation and pH-regulation. By analyzing the localization and functioning of ion-transport mechanisms, we obtain information about the cause and meaning of electrochemical phenomena during development.

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Summary of analyzed ion-transport mechanisms and their supposed directions of ion flow in ovarian follicles

Selected publications:

 


(Studies supported by the DFG and the RWTH Aachen)