MEASUREMENT OF FREE CALCIUM IN SINGLE FROG OOCYTES

某些外部刺激会导致游离钙水平的增加， 青蛙卵母细胞的细胞质。衡量这一点的标准方法是 生物发光蛋白水母发光蛋白，它与钙反应， 光该项目的目标是能够测量相对 通过测量各种刺激剂产生的钙的量， 刺激后发射的光子数。所发射的光处于 极低的水平-大约每秒50个光子-所以一个非常低的黑暗 使用电流光电倍增管和冷却外壳。卵母细胞 插入到一个特殊设计的停流池中， 刺激可以很快改变。特殊的光学系统被用来捕捉 尽可能多的光，并将其聚焦在光电倍增管上。

Certain external stimuli cause an increase in the free calcium level in the cytoplasm of a frog oocyte. The standard way to measure this is using the biological photoprotein aequorin, which reacts with calcium to emit light. The goal of the project is to be able to measure the relative amounts of calcium produced by various stimulating agents by measuring the number of photons emitted after the stimulus. The emitted light is at an extremely low level-about 50 photons per second--so a very low dark current photomultiplier tube and a cooled housing were used. The oocyte is inserted into a specially-designed stopped-flow cell so the external stimuli can be changed very quickly. Special optics were used to capture as much light as possible and focus it on the photomultiplier tube.