Animal Biodiversity and Evolutionary Biology

Many organisms communicate via chemical signals; for instance, fish release chemical cues via urine which tell other fish about their reproductive and social status, health, sex, and relatedness. The aim of the project is to identify some of these chemical signals for genetic  relatedness and understand their processing in the olfactory system.

Neurobiology

The first steps in vision require the precise communication between the different classes of retinal neurons and electrical synapses (gap junctions) contribute significantly to information processing within retinal networks. Projects 3.5.3. and 3.5.4. aim to elucidate the molecular characteristics  of selected retinal gap junctions (composition, interacting partners, post-translational modifications) and the signalling cascades involved in their modulation by using a multi-methodological approach (molecular techniques, proteomics, immunhistochemistry).

The mammalian retina uses several different pathways to process signals from rod photoreceptors. The most sensitive pathway relies on an electrical synapse between AII amacrine cells and ON bipolar cells. We aim to study the composition and light-dependent regulation of this electrical synapse (gap junction) using intracellular dye injections, STED microscopy, and biochemical techniques.

Organic Chemistry

Diaminoterephthalates are excellent fluorescent dyes which moreover define a mo­lecu­lar scaffold for binding up to four different effector groups or pharmacophores. This fluores­cent scaffold can be equipped with azides, alkynes or maleimides as reactive groups for binding pro­teins. Further­more, the fluorescence of maleimide-functionalized congeners is “tur­ned on” by the conjugate addition of thiols.

Neurochemistry

Stress responses and cell death mechanisms leading to sensory dysfunction
Abnormal protein accumulation and aggregation have been implicated in the pathogenesis of retinal dystrophies, leading to cell degeneration and death. Molecular mechanisms and signal transduction pathways underlying the regulation of cell death and survival will be evaluated. Special attention will be given to stress-induced changes in protein expression, the role of heat shock proteins and the involvement of autophagy in retinal cell deterioration.

Neurosensorik

Magnetic compass receptions takes place in the eyes of migratory birds. The process is light-dependent and most likely based on a quantum mechanical mechanism involving a long-lived radical pair. It is highly likely that one or more cryptochromes are involved as the primary sensory molecules. In this project we will investigate the occurrence and functional significance of the four different cryptochromes known from migratory bird retinae by using immunohistochemical and RNAi techniques.

Neurogenetics

A clinically important but poorly addressed issue in hearing disorders is the function of deafness genes beyond the cochlea. We aim to characterize the role of selected deafness associated transcriptional regulators/signaling molecules in the auditory brainstem by using the Cre loxP system in mice. Fuctional consequences of these gene losses for development and function of the auditory brainstem will be investigated on the molecular and cellular level using gene expression profiling and high-end microscopy (STED).

Biochemistry

Conformational changes in multiprotein complexes operating in sensory transduction

The project is aimed at investigating catalytic site and switch mechanisms in signaling proteins like guanylate cyclases and calcium sensor proteins. Methods to perform the tasks will include site-directed mutagenesis, protein chemistry, surface plasmon resonance and time-resolved fluorescence spectroscopy.

Energy and Semiconductor Research Laboratory (EHF)

Designing and Developing Selective Surfaces for Biomolecular Uptake and Release in Cellular Systems

The aim of this project is to look at adsorption, electrostatic binding, and voltage regulated release of biomolecules to and from modified electrode surfaces. Their complex interaction, particularly in case of the neural transmitter L-glutamate, representing the major excitatory amino acid in the brain, will be analyzed via electrochemical, optical, and surface sensitive measurement techniques. In a first step, we focus on electrode prototypes coated with a molecularly selective polymer, in order to cope with the excitotoxic effects of glutamate on neural cellular systems.

Molecular Microbiology

The model bacterium “Aromatoleum aromaticum” strain EbN1 degrades structurally very similar aromatic acids (benzoate, phenylacetate and 3-phenylpropanoate), phenolic compounds (phenol and p-ethylphenol) and alkylbenzenes (toluene and ethylbenzene) via different pathways. Differential expression of the respective catabolic operons is strictly substrate-specific and proposed to be mediated by compound-specific sensory/regulatory systems, as inferred from genome analysis and differential proteomics. By a combination of physiological, bioinformatic, molecular genetic and proteomic approaches we want to elucidate modes of operation and molecular mechanisms of the sensory systems enabling this fine-tuned discrimination between chemically similar compounds.