Correspondence

This study presents morphological and biochemical evidence of programmed cell death (PCD) in Entamoeba histolytica induced by exposure of trophozoites to the aminoglycoside antibiotic G418. Morphological characteristics of PCD, including cell shrinkage, reduced cellular volume, nuclear condensation, DNA fragmentation and vacuolization were observed, with preservation of trophozoite membrane integrity. PCD is orchestrated biochemically by alterations in intracellular ion fluxes. In G418-treated trophozoites, overproduction of reactive oxygen species (ROS), decreased intracellular K+, increased cytosolic calcium, and decreased intracellular pH levels were observed. However, externalization of phosphatidylserine was not detected. These results suggest that amoebae can undergo PCD under stress conditions, and that this PCD shares several properties with PCD reported in mammals and in a variety of unicellular organisms