Pathways involved in environmental sensing in trypanosomatids

Digenetic parasites, such as those of the order Kinetoplastida, must respon d to extracellular and intracellular signals as they adapt to new environme nts within their different hosts. Evidence for signal transduction has been obtained for Trypanosoma brucei, T. cruzi and Leishmania, as reveiwed here by Marilyn Parsons and Larry Ruben. Although the broad picture suggests si milarities with the mammalian host, there are large gaps in our understandi ng of these processes; this probably contributes to a perception of differe nces. Nonetheless, current evidence suggests that the trypanosomatids might lack certain classes of signalling molecules found in other organisms.