荧光探针与分子传感器演示文稿.pptVIP

脱氧胸腺嘧啶核苷二聚体，分别连接能量给体（荧光素）和能量受体（罗丹明）。羟基自由基作用前，测得能量转移荧光，羟基自由基作用后，磷酸连接体断裂，能量转移荧光消失。 * Fura-2 and indo-1 (Fura and Indo Ratiometric Calcium Indicators) are UV light–excitable, ratiometric Ca2+ indicators that are generally considered to be interchangeable in most experiments. Fura-2 has become the dye of choice for ratio-imaging microscopy ( ), in which it is more practical to change excitation wavelengths than emission wavelengths. Upon binding Ca2+, fura-2 exhibits an absorption shift that can be observed by scanning the excitation spectrum between 300 and 400 nm, while monitoring the emission at ~510 nm (Figure 19.3). In contrast, indo-1 is a preferred dye for flow cytometry, where it is more practical to use a single laser for excitation — usually the 351–364 nm spectral lines of the argon-ion laser — and monitor two emissions. The emission maximum of indo-1 shifts from ~475 nm in Ca2+-free medium to ~400 nm when the dye is saturated with Ca2+ (Figure 19.4). * * * False-color image（假色成像） of free Ca2+ concentration in a Purkinje neuron （梨状神经元）from embryonic mouse cerebellum（胚鼠小脑）. Neurons were grown in dispersed tissue culture for 12 days, loaded with the pentapotassium salt of fura-2 (F1200) using a microelectrode and then challenged（活化） with trans-ACPD, an agonist（兴奋剂） of metabotropic glutamate receptors, in the absence of extracellular Ca2+. The composite image, which represents the ratio of images obtained with excitation at 340 nm and 380 nm, reveals the mobilization of internal Ca2+ stores without contribution from Ca2+ influx. The image was contributed by D.J. Linden, Johns Hopkins University, and M. Smeyne and J.A. Connor, Roche Institute of Molecular Biology. * * CA1 pyramidal neuron（锥形神经元） in a hippocampal slice（海马切片） filled with SBFI delivered from a patch pipette (visible on the right). The image was obtained using two-photon excitation of SBFI at 790 nm. Image contributed by Christine R. Rose, Physiological Institute, University of Munich. * * *