Colchicine, a drug which poisons the polymerization of microtubules,
was assayed for effects on the invasion of Plasmodium falciparum merozoites 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 schizonts was unaffected
by the drug. This was judged first by light microscopy, including morphology
and counts of nuclear particle numbers, then by ultrastructural studies
which excluded deranged organellogenesis as a cause of merozoite failure,
and finally by diachronic cultures in which both recruitment and loss of
schizonts could be counted. Specific invasion inhibition was seen when
10 μM–1 mM colchicine was present. Red cells
pre-incubated in colchicine and then washed showed no reduction in their
extent of invasion, and neither red cell lysis, sphering nor blebbing were
apparent. We conclude that intact microtubules are necessary for successful
merozoite function.