Entzeroth R, Dubremetz J F, Hodick D, Ferreira E
Eur J Cell Biol. 1986 Aug;41(2):182-8.
Merozoites of the parasitic protozoon Sarcocystis muris (Apicomplexa) possess three 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 21 kDa. 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 labeled by immunogold before and after invasion. After host cell invasion the parasite is enclosed in a secondary parasitophorous vacuole which contains an electron-dense material. This deposition was heavily labeled by anti 21 kDa antibodies which clearly demonstrated that the dense granule contents is released into the secondary parasitophorous vacuole.
寄生原生动物鼠肉孢子虫（顶复门）的裂殖子具有三种特征性细胞器，其内容物电子密度高，分别称为棒状体、微线体和致密颗粒，推测它们在入侵期间及入侵后参与寄生虫与宿主细胞的相互作用。通过在蔗糖密度梯度上离心，从裂殖子匀浆中纯化出致密颗粒。十二烷基硫酸钠-聚丙烯酰胺凝胶电泳显示，它们含有一种主要的21 kDa蛋白。针对该蛋白产生的多克隆抗体应用于宿主细胞入侵前后寄生虫的超薄冷冻切片和用Lowicryl-K4M包埋的切片。入侵前后，致密颗粒均被免疫金明显标记。宿主细胞入侵后，寄生虫被包裹在一个含有电子致密物质的次级寄生泡中。这种沉积物被抗21 kDa抗体大量标记，这清楚地表明致密颗粒的内容物被释放到次级寄生泡中。
