Immunoelectron micrographs. (A) Section of an early schizont of P.falciparum (Brazilian strain 7G8, drug sensitive) incubated with anti-CaM antibody and protein A-gold. Gold particles (arrows) are scattered diffusely over the schizont (S) cytoplasm. Little label is associated with the host erythrocyte (RBC). (x43,000.) (B) Section of merozoite. Gold particles indicate the location of CaM at the apical end (A) and the ductule of rhoptries (R). (x52,000.)Scheibel LW, Colombani PM, Hess AD, Aikawa M, Atkinson CT, Milhous WK. Calcium and calmodulin antagonists inhibit human malaria parasites (Plasmodium falciparum): implications for drug design. Proc Natl Acad Sci U S A. 1987 84:7310-4.

Ultrathin sections of merozoites were incubated with sheep Abs to calmodulin from bovine testis (these Abs are specific for all calmodulins found in all eukaryotic cells; It is not clear if the Ab reacted with all homologs of calmodulin or specifically with some of them) and then with protein-A gold. a. an are of intense immunoreactivity is located on the merozoite apical end. Some label was also noted immediately under the plasma membrane (arrows). b, e) Tangential section of the apical end of maturing merozoites, the calmodulin labeling is mostly on the polar rings.. A – apical end; R – rhoptry; Pr – polar ring. Bar= 0.1 mm.Matsumoto Y, Perry G, Scheibel LW, Aikawa M. Role of calmodulin in Plasmodium falciparum: implications for erythrocyte invasion by the merozoite. Eur J Cell Biol. 198745:36-43. Copyright Elsevier 2009.