How does wounding or amputation trigger proliferation of the planarian's stem cells? What signals are used to turn off proliferation after the appropriate amount of tissue has been regenerated? How is the proper pattern restored?

In contrast to commonly studied model invertebrates, planarians do not appear to segregate their germ cell lineage during early embryogenesis. Rather, the germ cells arise postembryonically and require inductive interactions for their specification. We are applying the tools of functional genomics to understand how the planarian stem cells are signalled to generate either oocytes or sperm at the appropriate time and place in the animal.

After amputation, planarians are able to regenerate a complete, functional central nervous system (CNS). We are studying a large collection of genes that are expressed in the CNS to identify molecules required for the proper re-wiring and patterning of the planarian CNS.