Not lost in translation Sensing the loss and filling the gap during regeneration

Every organism responds to injuries by reparative processes in order to adapt to the altered conditions. The quality of the adjustment in terms of morphological and functional recapitulation of the original status varies among species. One task is to understand the concepts by which animals with outstanding regenerative capabilities sense what and how much is missing, and how they translate that information to the appropriate responses. These concepts may integrate various kinds of regenerative phenomena although the specific molecular and cellular mechanisms that execute these processes are divergent and depend on the type of the injury. The use of a variety of lesion paradigms could uncover common principles that link injury to successful regeneration. In addition they could indicate means how to further translate this knowledge to the practice of regenerative medicine. We exemplify this possibility by outlining some critical features of dopaminergic neurogenesis in the midbrain of adult salamanders, and the implications for Parkinson's disease.