Plasmodium parasites cause malaria in mammalian hosts and are transmitted by Anopheles mosquitoes. Gametocytes, which differentiate from asexual-stage parasites, are activated by environmental changes when ingested into the mosquito midgut, and are rapidly released from erythrocytes prior to fertilization. Secretory proteins localized to osmiophilic bodies (OBs), organelles unique to gametocytes, have been reported to be involved in female gametocyte egress. In this study, we investigate the dynamics of OBs in activated gametocytes of Plasmodium falciparum and Plasmodium yoelii using the female OB-specific marker protein, G377. After activation, female gametocyte OBs migrate to the parasite surface and fuse to form large vesicles beneath the parasite plasma membrane. At the marginal region of female gametocytes, fused vesicles secrete contents by exocytosis into the parasitophorous vacuole space, prior to parasite egress via the break-down of the erythrocyte membrane. This is the first detailed description of how proteins are transported through osmiophilic bodies.

疟原虫寄生虫在哺乳动物宿主中引起疟疾，并由蚊子按蚊传播。与无性期寄生虫不同的配子细胞在被摄入蚊子中肠时会被环境变化激活，并在受精前迅速从红细胞中释放出来。据报道，定位于亲卵小体（OBs）的分泌蛋白是配子体细胞特有的细胞器，参与了女性配子体细胞的排出。在这项研究中，我们调查OB的动力在配子体激活恶性疟原虫和氏疟原虫使用雌性OB特异性标记蛋白G377。激活后，雌性配子细胞OB迁移到寄生虫表面并融合，在寄生虫质膜下形成大的囊泡。在雌配子体细胞的边缘区域，融合的囊泡通过胞吐作用分泌到寄生虫的液泡空间，然后通过红细胞膜的分解而寄生虫逸出。这是蛋白质如何通过渗透性亲体转运的第一个详细描述。