Aikawa M, Kamanura K, Shiraishi S, Matsumoto Y, Arwati H, Torii M, Ito Y, Takeuchi T, Tandler B
Research Institute of Medical Sciences, Tokai University, Isehara, Japan.
Exp Parasitol. 1996 Dec;84(3):339-43. doi: 10.1006/expr.1996.0122.
Cerebral malaria, a severe complication of malaria, is caused by the obstruction of cerebral microvessels by Plasmodium falciparum-infected erythrocytes. Such cells adhere to endothelial cells by means of "knobs" induced on the red cell membrane by the parasites. When atomic force microscopy was used to investigate the structure of the knobs of unfixed infected red cells, each knob was found to consist of two distinct subunits, knob components that have never been seen in chemically fixed knobs examined by conventional transmission electron microscopy. Surface potential spectroscopy revealed that the knobs have a positive charge (+20 mV), whereas the remainder of the red cell plasma membrane is negatively charged. Since endothelial plasma membranes have a negative charge, the charge difference between knobs and endothelium may play a significant role in cytoadherence between the two cell types. The subunit structure of the knobs may be a steric necessity to align adherence molecules so that they can exert their effect. This study shows that the atomic force microscope has great potential for examination of cells in their native state; in combination with surface potential spectroscopy, it may uncover fundamental processes and mechanisms in cell function.
脑型疟疾是疟疾的一种严重并发症，由恶性疟原虫感染的红细胞阻塞脑微血管所致。此类细胞通过寄生虫在红细胞膜上诱导产生的“隆起”与内皮细胞黏附。当使用原子力显微镜研究未固定的感染红细胞隆起的结构时，发现每个隆起由两个不同的亚基组成，这是传统透射电子显微镜检查化学固定隆起时从未见过的隆起成分。表面电位光谱显示隆起带正电荷（+20 mV），而红细胞质膜的其余部分带负电荷。由于内皮细胞质膜带负电荷，隆起与内皮之间的电荷差异可能在两种细胞类型的细胞黏附中起重要作用。隆起的亚基结构可能是排列黏附分子以使其发挥作用的空间必需条件。这项研究表明，原子力显微镜在检查天然状态的细胞方面具有巨大潜力；与表面电位光谱相结合，它可能揭示细胞功能中的基本过程和机制。
