Cytochemical study of various stages of the life cycle of Toxoplasma gondii. 4. Dehydrogenases in the endozoa

Dehydrogenases of glycolysis, Krebs' cycle and pentosephosphate shunt are present in the metabolic machinery of toxoplasma endozoites (strain SS-119), thus suggesting a mixed oxidative metabolism in these. The enzymes are most commonly localized in the perinuclear area of the cytoplasm. Of special interest is the increased activity of some enzymes (especially lactate dehydrogenase) (fig HC) in the infected cells seen as definite layers of the stuff surrounding each parasite. This may correspond to the "overcoating" by mitochondrial material observed by Jones and Hirsch (1972) with the electron microscope. The importance of host-parasite relationships in the existence of the obligate intracellular parasite is discussed.