Microtubular organization visualized by immunofluorescence microscopy during erythrocytic schizogony inPlasmodium falciparumand investigation of post-translational modifications of parasite tubulin

Abstract

SUMMARYWe describe a novel procedure for the immunofluorescent investigation ofPlasmodium falciparum. This has allowed us to visualize clearly microtubular structures and their changing conformation through the erythrocytic cell-cycle, to the stage of cytodifferentiation leading to merozoite release. The images of spindle development we observed, together with an analysis of nuclear body numbers in large numbers of parasites, indicate that there is an apparent asynchrony in chromosomal multiplication within a single parasite. Using antibodies specific for post-translational modification of α- tubulin, we also demonstrate that the C-terminal tyrosine-containing epitope ofP. falciparumα-tubulin I is similar to that of other organisms. Lysine-40 in the same molecule, a target for highly specificin vivoacetylation in some organisms, is unmodified in the blood stages we examined here. Afterin vitroacetylation of this residue, however, the epitope to which it contributes was recognized by antibody, showing that the conformation of this part of the molecule is also conserved, despite a lack of primary sequence homology immediately downstream of the target lysine residue.