At present very little is known about the energy metabolism of Toxoplasma gondii except that Fulton and Spooner showed that a suspension of organisms utilizes glucose and oxygen. The organism is difficult to study because it is an obligate intracellular parasite. Not only does multiplication require an intracellular locus, but gradual death of organisms occurs when they are extracellular for any appreciable period of time. Since Toxoplasma can thrive in almost any mammalian cell or any cell in tissue culture, the factors which are provided by the cell must be simple and nearly universal. It is the purpose of this study to employ enzyme histochemistry to ascertain the presence, activity and location within the organisms of enzymes associated with respiration, and to compare the apparent enzyme activities of proliferative and encysted parasites.
Tetrazolium stains permit selective demonstration of the various enzymes of glycolysis, the Kreb's cycle, and the electron transport chain in encysted as well as proliferative forms of Toxoplasma and permit localization of these enzymes within the organism.