National Research Center for Protozoan Diseases, Obihiro University of Agriculture and Veterinary Medicine, Inada-cho, Obihiro, Hokkaido 080-8555, Japan.
Exp Parasitol. 2011 Jun;128(2):176-80. doi: 10.1016/j.exppara.2011.02.011. Epub 2011 Feb 16.
The infection by the malaria parasite of its mammalian host is initiated by the asexual reproduction of the parasite within the host hepatocyte. Before the reproduction, the elongated sporozoites undergo a depolarizing morphogenesis to the spherical exo-erythrocytic form (EEF). This change can be induced in vitro by shifting the environmental conditions, in the absence of host hepatocytes. Using rodent malaria parasites expressing a FRET-based calcium sensor, YC3.60, we observed that the intracellular calcium increased at the center of the bulbous structure during sporozoite transformation. Modulators of intracellular calcium signaling (A23187 and W-7) accelerated the sporozoite-rounding process. These data suggest that calcium signaling regulates the morphological development of the malaria parasite sporozoite to the EEF, and support a fundamental role for calcium as a universal transducer of external stimuli in the parasitic life cycle.
疟原虫感染其哺乳动物宿主是由寄生虫在宿主肝细胞内的无性繁殖引发的。在繁殖之前，长形的子孢子经历去极化形态发生，形成球形的外血红细胞前体（EEF）。这种变化可以在没有宿主肝细胞的情况下，通过改变环境条件在体外诱导。使用表达基于荧光共振能量转移（FRET）的钙离子传感器 YC3.60 的啮齿动物疟原虫，我们观察到在子孢子转化过程中，钙离子在球茎状结构的中心增加。细胞内钙信号转导的调节剂（A23187 和 W-7）加速了子孢子变圆的过程。这些数据表明，钙信号调节疟原虫子孢子向 EEF 的形态发育，并支持钙作为寄生虫生命周期中外来刺激的通用转导物的基本作用。
