A ROLE FOR MICROTUBULES IN PLASMODIUM-FALCIPARUM MEROZOITE INVASION

Colchicine, a drug which poisons the polymerization of microtubules, w as assayed for effects on the invasion of Plasmodium falciparum merozo ites into red cells in order to investigate if merozoite microtubules have a function in invasion. Culture conditions and concentrations of colchicine were established where the maturation and rupture of schizo nts was unaffected by the drug. This was judged first by light microsc opy, including morphology and counts of nuclear particle numbers, then by ultrastructural studies which excluded deranged organellogenesis a s a cause of merozoite failure, and finally by diachronic cultures in which both recruitment and loss of schizonts could be counted. Specifi c invasion inhibition was seen when 10 mu M-1 mM colchicine was presen t. Red cells pre-incubated in colchicine and then washed showed no red uction in their extent of invasion, and neither red cell lysis, spheri ng nor blebbing were apparent. We conclude that intact microtubules ar e necessary for successful merozoite function.