Kudryashev Mikhail, Lepper Simone, Baumeister Wolfgang, Cyrklaff Marek, Frischknecht Friedrich
Parasitology, Department of Infectious Diseases, University of Heidelberg Medical School, Im Neuenheimer Feld 324, D-69120 Heidelberg, Germany.
PMC Biophys. 2010 Mar 5;3(1):6. doi: 10.1186/1757-5036-3-6.
Polymerization of actin into filaments can push membranes forming extensions like filopodia or lamellipodia, which are important during processes such as cell motility and phagocytosis. Similarly, small organelles or pathogens can be moved by actin polymerization. Such actin filaments can be arranged in different patterns and are usually hundreds of nanometers in length as revealed by various electron microscopy approaches. Much shorter actin filaments are involved in the motility of apicomplexan parasites. However, these short filaments have to date not been visualized in intact cells. Here, we investigated Plasmodium sporozoites, the motile forms of the malaria parasite that are transmitted by the mosquito, using cryogenic electron tomography. We detected filopodia-like extensions of the plasma membrane and observed filamentous structures in the supra-alveolar space underneath the plasma membrane. However, these filaments could not be unambiguously assigned as actin filaments. In silico simulations of EM data collection and tomographic reconstruction identify the limits in revealing the filaments due to their length, concentration and orientation.PACS Codes: 87.64.Ee.
肌动蛋白聚合成丝可以推动细胞膜形成丝状伪足或片状伪足等延伸结构，这些结构在细胞运动和吞噬作用等过程中很重要。同样，小细胞器或病原体也可以通过肌动蛋白聚合而移动。通过各种电子显微镜方法可以发现，此类肌动蛋白丝可以以不同的模式排列，长度通常为数百纳米。更短的肌动蛋白丝参与顶复门寄生虫的运动。然而，迄今为止，这些短丝在完整细胞中尚未被观察到。在这里，我们使用低温电子断层扫描技术研究了疟原虫的子孢子，即由蚊子传播的疟原虫的活动形式。我们检测到了质膜丝状伪足样延伸，并在质膜下方的肺泡上间隙中观察到了丝状结构。然而，这些丝不能明确地确定为肌动蛋白丝。对电子显微镜数据收集和断层扫描重建的计算机模拟确定了由于丝的长度、浓度和方向而在揭示丝方面存在的局限性。
PACS代码：87.64.Ee。
