Principal Investigator Joern Dunkel
Asexual reproduction by fission or budding is a characteristic feature of bacteria and single cell eukaryotes, such as yeast or amoeba. Higher multicellular organisms usually reproduce sexually, because they lack the regenerative capabilities required for asexual reproduction. Exceptions are hydras and planarians (flatworms) which can reproduce both sexually and asexually. Hydras are relatively primitive organisms composed of only a very small number of cell types. By contrast, planarians are bilaterally symmetric animals, possess all three germ layers, a complex central nervous system and many of their genes can also be found in humans. Planarians exhibit amazing regenerative abilities, facilitated by stem cells that are distributed throughout their bodies. These stem cells not only enable the worms to heal without scarring after wounding, but also allow for asexual reproduction: In the course of a fission cycle, planarians can split in two or more pieces and subsequently regenerate the missing body parts within a few days. In collaboration with the Collins lab, we have studied internal and external factors that can affect the fission and population dynamics in the asexual freshwater planarian species Schmidtea mediterranea.