Visualization of the mitochondria ofToxoplasma gondii-infected mouse fibroblasts by the cationic permeant fluorescent dye rhodamine 123

Summary The mitochondria of living mouse fibroblasts infected withToxoplasma gondii were monitored with the cationic permeant fluorescent dye rhodamine 123. Fluorescence microscopy revealed that host cell mitochondria accumulated at the cytoplasmic surface of parasitophorous vacuoles and increased the dye uptake in the periparasitophorous vacuole asT. gondii multiplied.The author wishes gratefully to acknowledge the work of Miss Mayumi Kato and Mr. Isao Kimata in preparing the photographs. The publication cost was supported by a grant of the Ohyama Health Foundation.