Catecholamines inEntamoebae: Recent (re)discoveries

Free-living and enteric amoebae have similar two-stage life cycles, and both organisms depend on being able to monitor environmental conditions to determine whether to continue multiplying as trophozoites, or to differentiate into dormant or transmissible cysts. Conditions that support high trophozoite densities might also be expected to select for mechanisms of information exchange between these cells. We recently determined that trophozoites of at least one species ofEntamoeba release and respond to catecholamine compounds during differentiation from the trophozoite stage into the cyst stage. It turns out that this is not an entirely novel finding, as a number of previous studies have demonstrated parts of this story in free-living or enteric amoebae. We briefly review here major points of the previous studies and describe some of our recent results that have extended them.