GAMETOCYTOGENESIS INDUCTION BY AMMONIUM-COMPOUNDS IN CULTURED PLASMODIUM-FALCIPARUM

Asexual parasites of a strain that seldom or never produce gametocytes in in vitro culture began gametocytogenesis after 24 h treatment with RPMI 1640 medium containing concanavalin A (final concentration, 10 μg ml-1) and ammonium carbonate (final concentration, 15 mm ml-1) or ammonium bicarbonate (final concentration, 15 mm ml-1). Gametocytogenesis was consistently observed from the 3rd day after the treatment. Concanavalin A enhanced gametocytogenesis induction by ammonium carbonate or ammonium bicarbonate, although concanavalin A does not itself have gametocytogenesis induction activity. Whereas no gametocytogenesis was observed after addition of concanavalin A and ammonium acetate (final concentration, 5-25 mm ml-1) or ammonium chloride (final concentration, 5-15 mm-1). Addition of ammonium compounds resulted in decrease of parasitemia, regardless of gametocytogenesis. © 1990.