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Portfolio of my current research projects

Origin and ancestral function of the nervous system

We strive to gain insights into the ancestral complexity and function of the nervous system. Using single-cell transcriptomics, comparative genomics and functional analysis by transgenesis, we uncover a remarkable complexity of the nervous systems in pre-bilaterian Metazoa. Our findings suggest that the nervous system might have emerged in the evolution in a tight interaction with the microbial environment (Klimovich & Bosch, 2018). In our resent study, we show that the ancestral pacemaker neurons emerged as immunocompetent cells that directly interact with the commensal microbiota. 

This project is a part of our long-term collaboration with Prof. Igor Adameyko (Medical University Vienna/Karolinska Institute).  

Architecture, activity and plasticity of simple nervous systems

We are interested in uncovering the fundamental principles of neuronal network topology, activity, plasticity, and energy efficiency. To this end, we combine experimentation on Hydra with computational modelling approaches. This project is a part of a newly established Collaborative Research Center 1461 "Neurotronics: Bio-inspired Information Pathways" funded by the German Science Foundation (DFG). Together with the group of Prof. Claus Hilgetag (UKE, Hamburg), we develop computational models of network topology and activity to explore how developmental constraints and basic plasticity rules lead to emergence of complex activity patterns and behaviours.

Evolutionary role of taxonomically-restricted genes

Recently, we uncovered a surprising abundance and diversity of transcripts encoded in taxonomically-restricted genes (TRGs) in Hydra neurons. What role do these cnidarian- and even Hydra-specific genes play? Why is the nervous system particularly enriched in TRG products? We attempt to address these questions using bioinformatic approaches combined with functional studies on transgenic Hydras

Evolutionary roots of tumor formation

How old are tumors? Are all animals capable of developing tumors? We have provided the first evidence for naturally occurring tumors in two Hydra species (Domazet-Loso, Klimovich et al., 2014). This study suggests that tumor formation is as old as multicellularity. In this project, we join efforts with Assoc. Prof. Tomislav Domazet-Loso (Ruder Boskovic Institute, Zagreb). 

Recently, we demonstrated that the tumor development in Hydra is caused by an interaction between an environmental bacterium Turneriella and the Hydra-associated resident Pseudomonas bacterium (Rathje et al., 2020). We continue exploring the evolutionary and ecological implications of tumor formation in collaboration with Frédéric Thomas (CREEC, Montpellier).

Transgenesis in Hydra

Developmental studies on Hydra rely on in vivo tracing of cells and on the functional analysis of genes by transgenesis. Therefore, we not only implement the previously developed tools of transgenesis in Hydra, but also improve them and develop new approaches. We have developed the first inducible gene expression system in Hydra (Klimovich et al., 2019). Recently, we also developed a versatile transgenesis system for selective cell ablation in Hydra (unpublished). With Jörg Wittlieb, we generate transgenics on routine basis at the Transgenic Hydra Facility in Kiel University (

Projects: Projects
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