Watanabe Tomonobu M, Sato Takashi, Gonda Kohsuke, Higuchi Hideo
Biomedical and Engineering Research Organization, Tohoku University, Sendai, Miyagi 980-8579, Japan.
Biochem Biophys Res Commun. 2007 Jul 20;359(1):1-7. doi: 10.1016/j.bbrc.2007.04.168. Epub 2007 May 4.
Dual-focus imaging optics for three-dimensional tracking of individual quantum dots has been developed to study the molecular mechanisms of motor proteins in cells. The new system has a high spatial and temporal precision, 2 nm in the x-y sample plane and 5 nm along the z-axis at a frame time of 2 ms. Three-dimensional positions of the vesicles labeled with quantum dots were detected in living cells. Vesicles were transported on the microtubules using 8-nm steps towards the nucleus. The steps had fluctuation of approximately 20 nm which were perpendicular to the axis of the microtubule but with the constant distance from the microtubule. The most of perpendicular movement was not synchronized with the 8-nm steps, indicating that dynein moved on microtubules without changing the protofilaments. When the vesicles changed their direction of movement toward the cell membrane, they moved perpendicular with the constant distance from the microtubule. The present method is powerful tool to investigate three dimensional movement of molecules in cells with nanometer and millisecond accuracy.
已开发出用于单个量子点三维跟踪的双聚焦成像光学系统，以研究细胞中运动蛋白的分子机制。新系统具有很高的空间和时间精度，在x-y样本平面中为2纳米，在z轴上为5纳米，帧时间为2毫秒。在活细胞中检测到用量子点标记的囊泡的三维位置。囊泡在微管上以8纳米的步长向细胞核运输。这些步长有大约20纳米的波动，垂直于微管轴，但与微管保持恒定距离。大部分垂直运动与8纳米步长不同步，这表明动力蛋白在微管上移动时不改变原纤维。当囊泡改变其向细胞膜的运动方向时，它们垂直于微管并与微管保持恒定距离移动。本方法是一种强大的工具，可用于以纳米和毫秒精度研究细胞中分子的三维运动。
