Programmed cell death in Entamoeba histolytica induced by the aminoglycoside G418

1 Programa de Biomedicina Molecular ENMyH, Instituto Politécnico Nacional, CP 07320, Mexico 2 Escuela Militar de Graduados de Sanidad, UDEFA CP 11620, Mexico 3 Departamento de Inmunología, IIB, UNAM, Mexico 4 Departamento de Patología Experimental CINVESTAV-IPN, CP 07300, Mexico Correspondence D. Guillermo Pérez Ishiwara ishiwaramx{at}yahoo.com.mx 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. Abbreviations: BCECF, 2-,7-bis(2-carboxyethyl)-5-(and 6)-carboxyfluorescein; [Ca 2+ ] i , intracellular Ca 2+ concentration; DCFDA, dichlorodihydrofluorescein; , intracellular potassium; NT, not (G418) treated; PBFI-AM, potassium-binding benzofuran isophthalate; PCD, programmed cell death; pH i , intracellular pH; PI, propidium iodide; PS, phosphatidylserine; ROS, reactive oxygen species; TUNEL, terminal deoxynucleotidyl transferase-mediated biotin–dUTP nick end labelling