Immunoelectron microscopic demonstration of the exocytosis of dense granule contents into the secondary parasitophorous vacuole of Sarcocystis muris (Protozoa, Apicomplexa)
Entzeroth, R.; Dubremetz, J.F.; Hodick, D.; Ferreira, E.
European Journal of Cell Biology 41(2): 182-188
1986
ISSN/ISBN: 0171-9335 PMID: 3093233 Document Number: 267649
Merozoites of S. muris were shown to have 3 types of characteristic organelles with electron dense contents named rhoptries, micronemes, and dense granules, which are supposed to be involved in the parasite-host cell interactions during and after invasion. Dense granules were purified from a merozoite homogenate by centrifugation on a sucrose density gradient. It was shown by SDS polyacrylamide gel electrophoresis that they contain a major protein of MW 21 000. Polyclonal antibodies raised against this protein were applied to ultrathin frozen and Lowicryl-K4M-embedded sections of the parasite before and after host cell invasion. Dense granules were distinctly labelled by immunogold before and after invasion. After host cell invasion the parasite was enclosed in a secondary parasitophorous vacuole which contained an electron-dense material. This deposition was heavily labelled by anti-21 000 MW antibodies which clearly demonstrated that the dense granule contents are released into the secondary parasitophorous vacuole.