Projects

Aging in unicellular Eukaryotes

Unicellular Eukaryotes exhibiting an asymmetric mode of cell division represent valuable tools to study mechanisms and modulators of replicative and chronologic aging. The budding yeast Saccharomyces cerevisiae has been used as an aging model system and led to the identification of aging factors such as nutrient availability and signaling, autophagy and proteostasis, which modulate aging also in higher eukaryotes. In addition, pharmacological inhibition of nutrient signaling by rapamycin or rapamycin-derived drugs has life-span prolonging effects in various model systems.

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UNCD-based platforms for study of time-resolved neuronal signals

Due to the outstanding electrochemical properties, superior chemical inertness and biocompatibility, etc., diamond in a form of thin films with different crystallinities has been recognized as an extremely attractive material for (bio-)chemical sensing and as an interface to biological systems. The ultrananocrystalline diamond (UNCD) films deposited in our group by microwave plasma chemical vapor deposition from methane/nitrogen gas mixtures are composed of diamond nanocrystallites of up to 10 nm diameter embedded in an amorphous carbon matrix. Their surface is smooth with rms roughness of 10 – 14 nm and H-terminated, rounded nanostructures with diameters up to 100 nm dominate the topography. After surface modifications by different plasma and photochemical processes the UNCD surface can be rendered strongly hydrophilic (with O- or NH2-termination) or strongly hydrophobic (with F-termination). Furthermore, the surface termination can be patterned.

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Temporal control of fat metabolism in Dictyostelium

 In the unicellular amoebae Dictyostelium, as in many other single-celled eukaryotes and prokaryotes, starvation initiates a sequence of developmental events culminating in the formation of enduring spores that withstand adverse conditions such as cold, heat, drought, and of course, nutrient deprivation. Intracellular food reserves should help the cells to survive starvation, but surprisingly in the case of Dictyostelium amoebae, accumulated storage fat prevents most of the cells from becoming spores. Within the “clocks” network, we will investigate the timing of the cell’s decision to become a spore or to fail, taking the initiation of starvation as the set point.

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Localization and interaction of PDF neuropeptides in Onychophora and Tardigrada

Although numerous studies have been performed on pigment-dispersing factor neuropeptides (PDFs) in arthropods – a neuropeptide, which acts as a circadian neuromodulator – only little is known about the expression and interaction of PDFs with their receptors in the closest relatives of arthropods, the onychophorans (velvet worms) and tardigrades (water bears). The aim of our project is therefore to localize the two identified PDF neuropeptides in onychophorans and the three PDFs in tardigrades together with their respective receptors using immunolabelling with specific antibodies.

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The role of Orco in hawkmoth pheromone transduction and in the control of circadian changes in olfactory sensitivity

Insect odor transduction is still not resolved, despite the fact that its understanding is a crucial prerequisite to controlling the behaviour of pest, vector, or beneficial insects. Odours from the environment and pheromones (species-specific odours) can be detected via odour receptor neurons (ORNs) on insect antennae. It is well known that insect olfactory receptors (ORs) expressed in ORNs consist of a highly conserved olfactory receptor co-receptor (Orco) subunit and a highly variable ligand-binding OR subunit. Orco locates and maintains ORs in ciliary membranes as prerequisite to odor responses (termed chaperone function). Despite several excellent investigations, it remains unclear how Orco and OR proteins interact with each other during odor transduction. 

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Morphological and functional examination of neuropeptides in the circadian system of Rhyparobia maderae with focus on myoinhibitory peptides

The cockroach Rhyparobia maderae is an established model organism for circadian research. Transplantation experiments located the circadian clock that controls rest-activity cycles to the accessory medulla (AME) with innervating pigment-dispersing factor (PDF) expressing neurons. The AME is a small optic lobe neuropil innervated by about 240 neurons belonging to 8 soma groups that are enriched in neuropeptides. Among all AME clock neurons the 12 anterior PDF expressing cells are studied best. Two of them co-express myoinhibitory peptides (MIPs). We want to understand the function of MIP in the circadian system of the cockroach.

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Functional characterization of circadian clock neuronal circuits controlling sleep-wake rhythms in the Madeira cockroach Rhyparobia maderae

The cockroach Rhyparobia maderae is an established model organism for circadian research. Transplantation experiments located the circadian clock that controls rest-activity cycles to the accessory medulla (AME) with innervating pigment-dispersing factor (PDF) expressing neurons. The AME is a small optic lobe neuropil innervated by about 240 neurons belonging to 8 soma groups that are enriched in neuropeptides. Among all AME clock neurons the 12 anterior PDF expressing cells are studied best. Two of them co-express myoinhibitory peptides (MIPs). We want to understand the function of MIP in the circadian system of the cockroach.

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How can rhythmic extracellular/environmental signals generate highly specific, rhythmic cellular responses at different time scales, while the repertoire of intracellular second messengers is limited?

Clock cells can sense regular environmental rhythms at different time scales, such as the 24h light dark cycle or the superimposed ultradian rhythm in the change of light intensity at dusk and dawn. They transduce these environmental rhythms into respective intracellular rhythms of “second messengers” as well as in regular release of coupling factors such as neuropeptides. The rhythmically released neuropeptides in turn will generate intracellular changes of second messengers in all neuropeptide receptor expressing cells at the time course of the environmental cues.

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