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.
