MICROTUBULES IN PLASMODIUM-FALCIPARUM MEROZOITES AND THEIR IMPORTANCEFOR INVASION OF ERYTHROCYTES

Plasmodium falciparum merozoites have an array of 2-3 subpellicular mi crotubules, designated f-MBST. We have previously shown that colchicin e inhibits merozoite invasion of erythrocytes, indicating a microtubul ar involvement in this process. Colchicine inhibition of invasion was reduced by the Taxol(R)-stabilization of merozoite microtubules prior to colchicine exposure. Immunofluorescence assays showed that the numb er and length of f-MASTs were reduced in colchicine-treated merozoites , confirming that microtubules were the target of colchicine inhibitio n. The dinitroaniline drugs, trifluralin and pendimethalin, were shown by immunofluorescence to depolymerize the f-MAST and both drugs were inhibitory in invasion assays. These results demonstrate that the inte grity of the f-MAST is important for successful invasion. Fluorescence imaging demonstrated the alignment of mitochondria to f-MAST, suggest ing that mitochondrial transport might be perturbed in merozoites with disorganized f-MAST. Depolymerizing mt in late-stage schizonts did no t affect the allocation of mitochondria to merozoites.