Isolation and partial characterization of rhoptries and micronemes from Eimeria nieschulzi zoites (Sporozoa, Coccidia).

Homogenization and subcellular fractionation of sporozoites of Eimeria nieschulzi have allowed the recovery of highly enriched fractions of rhoptries and micronemes. The isolated organelles kept their in situ morphological characteristics. Their apparent densities in sucrose solutions were approximately 1.18 g/cm3 for rhoptries and 1.14 g/cm3 for micronemes. When subjected to sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), the microneme fraction showed two major polypeptides at 220 and 94 kDa. The rhoptry fraction contained at least three predominant peptides at 200, 150, and 63 kDa. Micronemes were also isolated from third-generation merozoites of the same species; their characteristics were identical to those of the organelles isolated from sporozoites.