应用荧光探针研究菠菜叶绿体膜对低强度电磁场的辐射敏感性

应用ANS渗入菠菜叶绿体膜后的ANS荧光光谱和光合细胞Chla荧光参数的变化研究了菠菜叶绿体膜对辐射功率密度为5 mW·cm-2以下的300 MHz低强度电磁场的辐射敏感性。研究发现，在1～5 mW·cm-2的低强度电磁场作用下，菠菜叶绿体ANS荧光光谱的位置没有明显变化，但ANS荧光强度明显增大，表明低强度电磁场使菠菜叶绿体膜流动性变小。1～5 mW·cm-2低强度电磁场的作用还使菠菜叶绿体发出的Chla荧光参数F₀减小，f_V／F₀,F_V／F_m和ΔF_V／T增大，F_VI／F_V减小，表明低强度电磁场使菠菜叶绿体膜发生了光系统Ⅱ(PSⅡ)无活性中心向有活性中心的转变，PSⅡ潜在活性提高、光合电子传递过程加快，原初光能转换效率增强。菠菜叶绿体膜ANS荧光和Chla荧光对低强度电磁场的这种辐射敏感性说明了低强度电磁场能对菠菜光合作用系统产生非热效应，并且，菠菜光合细胞有可能通过PSⅡ活性中心异质性的转变来适应电磁辐射增强的环境。

Fluorescence Used to Investigate the Sensitivity of Spinach Chloroplast Membrane to Low Intensity Electromagnetic Radiation

A system for studying biological effect of radio frequency electromagnetic field was developed. The system can form an area where electromagnetic wave with large frequency range is well distributed. The strength of electromagnetic wave was measured easily. Electromagnetic wave in the system did not have effect on environment. The sensitivity of spinach chloroplast membrane to low intensity electromagnetic radiation of 300 MHz under power density of 5 mW·cm-2 was studied by the spectral analysis method of fluorescence of 8-anilino-1-naphthalene-sulfonic acid (ANS) and the changes in chlorophyll a (Chla) fluorescence parameters of spinach chloroplast membrane. The result showed that the position of spectrum of ANS fluorescence of spinach chloroplast membrane did not change, but the intensity of ANS fluorescence was obviously increased under the action of electromagnetic radiation with power density of 1-5 mW·cm-2. There was an increase in the intensity of ANS fluorescence with the increase in electromagnetic radiation. The increase of ANS fluorescence of spinach chloroplast membrane showed that low level electromagnetic field induced the decrease in fluidity of chloroplast membrane compared with control experiment. The cause of the change in the fluidity could be related to the polarization of chloroplast membrane under the electromagnetic field. The analysis of Chla fluorescence parameters of spinach chloroplast membrane indicated that low level electromagnetic field of 300 MHz made the fluorescence parameters Ｆ０ and ＦＶＩ／ＦＶ decrease, and ＦＶ／Ｆ０, ＦＶ／Ｆｍ and ΔＦＶ／Ｔ increase. It was showed that low level electromagnetic field caused the change of non-active center of photosystem Ⅱ of spinach chloroplast membrane to active center and the increase in potential active and photochemical efficiency of PSⅡ, and promoted the transmit process of electron in photosynthesis of chloroplast membrane of photosynthesis cell in spinach leaf. The study confirmed that low level electromagnetic field has non-thermal effects on photosynthesis system of spinach chloroplast membrane. The cell in spinach leaf can keep the photosynthesis through the change in heterogeneity of photosystem Ⅱ and adapt to the environment of electromagnetic radiation increase.