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Research

An increasing interest is directed today to the understanding of the role of chemical interactions in aquatic systems. Our group focuses on two major aspects of aquatic chemical ecology – biochemical determinants of food quality and chemical communication in predator-prey interactions.
Our approach is a combination of analytical chemistry and molecular biology with field work and highly controlled experiments in meso- and microcosms. In addition to ecological field techniques we are using a wide array of methods that cover HPLC, GC and GC-MS, Real-Time PCR and 2-D-gelelectrophoresis, which are always closely linked to bioassays.

Food quality is determined largely by the biochemical composition of food organisms. We investigate factors that are responsible for the nutritional quality of primary producers in freshwater (algae and cyanobacteria) for various aquatic invertebrate herbivores.
Our research has focused on polyunsaturated fatty acids (PUFAs) and sterols in algae and cyanobacteria as determinants of the trophic transfer efficiency to herbivorous invertebrates. Currently we investigate genotype dependent variation of the demand of these essential lipids and the underlying genetics in different Daphnia species.
Cyanobacteria are well known for a variety of inhibitory secondary metabolites, of which protease inhibitors are the most frequently produced inhibitors. We are investigating how these cyanobacterial protease inhibitors interact with digestive proteases of Daphnia. Analyses of gene expression and proteome of Daphnia have revealed a high degree of plasticity with respect to proteases.
Currently we focus on molecular evolution in Daphnia populations in response to cyanobacteria.

Aquatic ecosystems are ideally suited for communication via chemical cues since infochemicals can be easily distributed in concentrations sufficient for a response. Therefore, it is not surprising that infochemicals are involved in the location of prey, predators, food, and partners and may be used in kin recognition.
In our group we investigate several of these infochemical-mediated interactions that play a crucial role in structuring aquatic food webs. We are participating in the  Daphnia Genomics Consortium (DGC) that is working since 2003 on establishing Daphnia as a new model organism and has  succeeded only recently.
We work on kairomones from the predator fish that induce defenses in Daphnia. The defenses are changes in behaviour and life-history of Daphnia. In this context we use HPLC and proteomics to identify the kairomones and to understand the molecular basis of the response in Daphnia.