State Key Laboratory of Silkworm Genome Biology, Southwest University, Chongqing, China.
Chongqing Key Laboratory of Microsporidia Infection and Control, Southwest University, Chongqing, China.
mSphere. 2020 Feb 12;5(1):e00958-19. doi: 10.1128/mSphere.00958-19.
Microsporidia are obligate intracellular parasites that infect a wide variety of host organisms, including humans. The sporoplasm is the initial stage of microsporidian infection and proliferation, but its morphological and molecular characteristics are poorly understood. In this study, the sporoplasm of was successfully isolated and characterized after the induction of spore germination The sporoplasm was spherical, 3.64 ± 0.41 μm in diameter, had the typical two nuclei, and was nonrefractive. Scanning and transmission electron microscopy analyses revealed that the sporoplasm was surrounded by a single membrane, and the cytoplasm was usually filled with relatively homogeneous granules, possibly ribosomes, and contained a vesicular structure comprising a concentric ring and coiled tubules. Propidium iodide staining revealed that the sporoplasm membrane showed stronger membrane permeability than did the cell plasma membrane. Transmission electron microscopy (TEM) revealed that the sporoplasm can gain entry to the host cell by phagocytosis. Transcriptome analysis of mature spores and sporoplasms showed that 541 significantly differentially expressed genes were screened (adjusted value [] < 0.05), of which 302 genes were upregulated and 239 genes were downregulated in the sporoplasm. The majority of the genes involved in trehalose synthesis metabolism, glycolysis, and the pentose phosphate pathway were downregulated, whereas 10 transporter genes were upregulated, suggesting that the sporoplasm may inhibit its own carbon metabolic activity and obtain the substances required for proliferation through transporter proteins. This study represents the first comprehensive and in-depth investigation of the sporoplasm at the morphological and molecular levels and provides novel insights into the biology of microsporidia and their infection mechanism. Once awoken from dormancy, the cellular matter of microsporidia is delivered directly into the host cell cytoplasm through the polar tube. This means that the microsporidia are difficult to study biologically in their active state without a contaminating signal from the host cell. Sporoplasm is a cell type of microsporidia , but relatively little attention has been paid to the sporoplasm in the past 150 years due to a lack of an effective separation method. , the first reported microsporidium, is a type of obligate intracellular parasite that infects silkworms and can be induced to germinate in alkaline solution We successfully separated the sporoplasm , and the morphological and structural characteristics were investigated. These results provide important insight into the biology and pathogenesis of microsporidia and potentially provide a possible strategy for genetic manipulation of microsporidia targeting the sporoplasm.
微孢子虫是一种专性细胞内寄生虫，感染范围广泛，包括人类。孢子是微孢子虫感染和增殖的初始阶段，但它的形态和分子特征尚未得到充分了解。在这项研究中，通过诱导孢子萌发成功分离和表征了 的孢子 。孢子呈球形，直径为 3.64±0.41μm，具有典型的双核，且非折射性。扫描和透射电子显微镜分析表明，孢子由单层膜包围，细胞质中通常充满相对均匀的颗粒，可能是核糖体，并包含一个由同心环和卷曲小管组成的泡状结构。碘化丙啶染色表明，孢子膜的膜通透性强于细胞质膜。透射电子显微镜（TEM）显示，孢子可以通过吞噬作用进入宿主细胞。成熟孢子和孢子的转录组分析表明，筛选出 541 个显著差异表达基因（调整后 值 [] < 0.05），其中 302 个基因上调，239 个基因下调。参与海藻糖合成代谢、糖酵解和戊糖磷酸途径的大多数基因下调，而 10 个转运体基因上调，这表明孢子可能抑制自身的碳代谢活性，并通过转运蛋白获得增殖所需的物质。本研究首次从形态和分子水平全面深入地研究了孢子，为微孢子虫生物学及其感染机制提供了新的见解。一旦从休眠中苏醒，微孢子虫的细胞物质就通过极管直接输送到宿主细胞质中。这意味着，如果没有宿主细胞的污染信号，微孢子虫在其活跃状态下进行生物学研究是非常困难的。孢子是微孢子虫的一种细胞类型，但在过去的 150 年中，由于缺乏有效的分离方法，相对较少关注孢子。是第一个被报道的微孢子虫，是一种专性细胞内寄生虫，感染家蚕，可以在碱性溶液中诱导萌发。我们成功地分离了 的孢子，并对其形态和结构特征进行了研究。这些结果为微孢子虫的生物学和发病机制提供了重要的见解，并可能为针对孢子的微孢子虫遗传操作提供一种可能的策略。
