The RFamide-positive neural network in an adult polyp

We study how cells make decisions during development and regeneration using molecular genetics, genomics, imaging, and functional studies. For our research, we use the cnidarian Hydractinia as a model system. This animal has quite unique biological features and can be manipulated with (relative) ease. 

Hydractinia is a clonal and colonial animal. Embryos develop within three days into a swimming larva called planula. Upon metamorphosis, which takes 24 hours, they transform into the adult form called a polyp. Polyps are sessile (we grow them on microscope glass slides). Upon metamorphosis, they start making genetic copies of themselves by asexual budding, forming a colony of genetically identical individuals (i.e. a clone).

The clonemates maintain tissue continuity, sharing a gastrovascular system (called stolon) and a nervous system – if you pinch one polyp, the entire colony will contract. In a way, a colony can be seen as a meta-individual. The animals can regenerate a fully functional individual from a tiny body fragment. They do not show any evidence for age-related deterioration, never get tumors (one can induce neoplasia by forced expression of some genes), and reproduce sexually on a daily basis.

Hydractinia possesses adult stem cells, known as i-cells. These cells are thought to contribute to all somatic lineages of the animal and to germ cells. i-cells are a major focus of our work. We study how they make different cell types like neurons and gametes. i-cells can migrate in the tissues and are recruited to major injury sites where they contribute to regeneration.