Our model systems
|The red flour beetle Tribolium castaneum is the second most developed genetic model system within arthropods surpassed only by Drosophila melanogaster. It represents the most species rich taxon on earth (Coleoptera) and in many respects, its biology is more typical for insects than the one of the fly Drosophila melanogaster. Technically, its major strength lies in the robust and systemic reverse genetics via RNAi gene knock-down. Further, a high quality genomic sequence is available and transgenesis and genome editing work efficiently in this species. Recently, resources for efficient mid and large scale RNAi screens have become available.
|Lymnaea stagnalis is a representative of the second largest animal phylum and is a member of the largest molluscan class, the Gastropoda. Despite their biological diversity, ancient evolutionary heritage and fascinating modes of development, molluscs are challenging to develop functional molecular tools for, and lag behind more advanced model systems in this respect. Despite these challenges L. stagnalis has long served as a model for neuroethology, eco-toxicology, morphological chirality and developmental biology. Lymnaea’s reproductive characteristics means that developmental material for study is available year-round with generation times being as short as 8 weeks. Stereotypical spiral cleaving embryos and larvae can be used to study spatial gene expression patterns, and a draft genome sequence along with a variety of transcriptome datasets are available for this species.
|The alphaproteobacterium Wolbachia is the most common, and arguably one of the most important inherited symbionts. Meta-analyses suggest that half of all arthropods are infected with Wolbachia. Using phylogenomic methods we found that the pandemic Wolbachia supergroups likely coincides with the evolution of holometabolous insects. The spread among arthropod hosts has been explained by horizontal transfer and for many strains it is known that they are able to manipulate the reproduction of their by induction of parthenogenesis, male killing, feminization and cytoplasmic incompatibility hosts to enhance their spread. Additionally, positive (or negative) fitness effects by impacting the immunity and physiology of their hosts seem to be of major importance for the establishment of novel infections. The combination of effects on the host made Wolbachia a powerful tool in the control of insects pests and human pathogens.
|Syllidae is the most diverse family of annelids characterized by its complex life cycles involving some of the most outstanding annelid reproductive strategies. Syllid reproductive modes sometimes imply the modification of the posterior body to form independent reproductive units (schizogamy) or the development of swimming adults (epigamy). Regenerative abilities are widespread in both epigamic and schizogamic syllids. All of them are able to regenerate posteriorly, while the complete anterior regeneration is more limited.
|Clytia hemisphaerica is a recently established emerging model system to study oogenesis and early embryonic development in a species at the base of animal phylogeny. A unique feature of this species is that the entire process of oogenesis can be followed by high-resolution live-cell microscopy within the isolated, transparent ovaries. In addition, the life cycle is short, including a vegetative polyp stage, which provides a continuous supply of genetically identical jellyfish, rendering this species well amenable to transgenesis. A set of recent studies have taken advantage of the assembled genome and transcriptome resources, and used this model system to revel novel features of conserved mechanism, for example, in regulation of oogenesis, origins of embryo polarity, embryonic pattering, germ-line origins or muscle evolution.
|Drosophila species We study the evolution of head morphology and eye size in two main groups of Drosophila. In the melanogaster group, we work with D. melanogaster, D. simulans and D. mauritiana and in the virilis group, we work with D. americana and D. novamexicana. We established strain-specific genomes for all species and various CRISPR/Cas9 tools are available in species of the melanogaster group.
|Beetles: Males of the broad horned flour beetle Gnathocerus cornutus develop exaggerated mandibles. We combine comparative transcriptomics and developmental characterization, as well as RNA interference (RNAi) to identify key genes regulating mandible growth in comparison to the red flour beetle Tribolium castaneum. A draft genome, as well as RNAi are established for G. cornutus.
|Comparative studies on Locusta migratoria (Orthoptera), Tribolium castaneum (Coleoptera) and Drosophila melanogaster (Diptera), in combination with available data from vertebrate species, suggest that complex apoptosis regulatory networks present in extant vertebrates already existed in early ancestors of metazoa. While apotosis control was subsequently simplified in C. elegans and D. melanogaster, other insects retained the complex vertebrate-like apoptosis regulation. Making use of differential accessibility of the three insect species mentioned above to different experimental approaches (survival assays, pharmacology, RNAi, expression studies etc.), we use whole animals, extracted tissues and cell cultures (neurons, hemocytes) to characterize regulatory mechanisms of insect apoptotis including possibilities to activate and interfere with cell death and loss of functions.
|Phasmatodeans are also large arthropods whose body size often exceeds that of the largest members of other insect groups. In my studies, I combine morphological and molecular techniques to explore evolutionary processes such as adaptive radiation and community assembly in geographic isolation, repeated evolution of convergent ecotypes and the loss (and regain) of complex character traits. Complementary lines of inquiry include issues related to taxonomy and systematics of stick insects, including extant and extinct forms, and using fossils as calibrations for divergence time analyses (i.e. dating phylogenetic trees).
|Chaetopterus – the so-called parchment worm – represents a remarkable and early branching member of the phylum Annelida. Chaetopterus can be fertilized in high numbers under lab conditions, shows a planktonic developmental cycle and exhibits an interesting phylogenetic position outside the annelid main radiation. Hence, numerous investigations dealing with immunohistochemical analyses, gene expression patterns or phylogenomic questions already exist, and provide the basis for future in-depth investigations using various approaches.
|Platynereis is a marine species, deeply nested within the tree of segmented worms (Annelida). Quite simple culture methods and a short lifecycle with non-feeding larvae that can be maintained under standardized lab conditions lead to many studies focussing on this annelid – reaching from general immunohistochemical investigations and comprehensive gene expression analyses to stable transgenesis and whole-body single cell studies. In summary, an in-depth knowledge and various protocols are already available for Platynereis, and provide the perfect background for further investigations.