Soft X-ray microscopy analysis of cell volume and hemoglobin content in erythrocytes infected with asexual and sexual stages of Plasmodium falciparum
Soft X-ray microscopy analysis of cell volume and hemoglobin content in erythrocytes infected with asexual and sexual stages of Plasmodium falciparum
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DOI：
10.1016/j.jsb.2011.09.003
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发表时间：
2012-02-01
影响因子：
3
通讯作者：
Tilley, Leann
中科院分区：
文献类型：
--
作者：
Hanssen, Eric;Knoechel, Christian;Tilley, Leann
恶性疟原虫（Plasmodiumfalciparum）是人类疟疾最致命的病原体，在红细胞内经历无性循环和性分化。随着红细胞内寄生虫的发育，它的大小增加，并改变宿主细胞质膜的通透性。一个有趣的问题是：在红细胞内循环过程中，宿主红细胞的完整性是如何维持的？我们已经使用水窗冷冻X射线断层扫描，以确定细胞形态和血红蛋白含量在不同阶段的无性和性分化。冷冻稳定保留了天然结构，允许精确分析寄生虫和宿主细胞体积。蛋白质对软X射线的吸收遵循比尔-朗伯定律，从而可以定量宿主细胞区室中血红蛋白的浓度。在无性发育期间，寄生虫的体积达到未感染红细胞体积的约50%，但感染的红细胞体积保持相对恒定。总血红蛋白含量在48小时周期内逐渐降低，但其浓度保持恒定，直到滋养体早期，降低25%，然后再次保持恒定，直到破裂前。在性发育早期，配子体具有与滋养体相似的形态，但随后经历了戏剧性的形状变化。我们的冷冻X射线断层扫描分析显示，约70%的宿主细胞血红蛋白被吸收和消化配子体发育过程中，寄生虫最终占据约50%的未感染的红细胞体积。受感染的红细胞的总体积保持恒定，除了在第四阶段有一些可逆的收缩，而血红蛋白的浓度降低到未感染红细胞的70%左右。(C)2011 Elsevier Inc. All rights reserved.
Plasmodium falciparum, the most virulent agent of human malaria, undergoes both asexual cycling and sexual differentiation inside erythrocytes. As the intraerythrocytic parasite develops it increases in size and alters the permeability of the host cell plasma membrane. An intriguing question is: how is the integrity of the host erythrocyte maintained during the intraerythrocytic cycle? We have used water window cryo X-ray tomography to determine cell morphology and hemoglobin content at different stages of asexual and sexual differentiation. The cryo stabilization preserves native structure permitting accurate analyses of parasite and host cell volumes. Absorption of soft X-rays by protein adheres to Beer-Lambert's law permitting quantitation of the concentration of hemoglobin in the host cell compartment. During asexual development the volume of the parasite reaches about 50% of the uninfected erythrocyte volume but the infected erythrocyte volume remains relatively constant. The total hemoglobin content gradually decreases during the 48 h cycle but its concentration remains constant until early trophozoite stage, decreases by 25%, then remains constant again until just prior to rupture. During early sexual development the gametocyte has a similar morphology to a trophozoite but then undergoes a dramatic shape change. Our cryo X-ray tomography analysis reveals that about 70% of the host cell hemoglobin is taken up and digested during gametocyte development and the parasite eventually occupies about 50% of the uninfected erythrocyte volume. The total volume of the infected erythrocyte remains constant, apart from some reversible shrinkage at stage IV, while the concentration of hemoglobin decreases to about 70% of that in an uninfected erythrocyte. (C) 2011 Elsevier Inc. All rights reserved.