ELEMENTAL MAPPING AT LOW DOSE

低剂量元素图谱

• 批准号: 6308950
• 负责人: JOSEPH S WALL
• 金额: $ 0.97万
• 依托单位: BROOKHAVEN SCIENCE ASSOC-BROOKHAVEN LAB
• 依托单位国家: 美国
• 财政年份: 2000
• 资助国家: 美国
• 起止时间: 2000-04-01 至 2001-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6308950
• 关键词: biomedical equipment development; biomedical resource; building /facility design /renovation; nucleic acids; proteins; technology /technique

The phosphorus L2, edge at 132 eV energy loss is very weak but provides an element-specificsignal. Direct imaging of phosphorus using electrons which have lost this amount of energy would require a dose much higher than that known to damage molecules. However low dose imaging is possible in the STEM using the simultaneously recorded dark field annular detector signal to locate particles for image averaging. Summing the weak phosphorus signal from several thousand aligned particles should be adequate to obtain a phosphorus map of essentially undamaged molecules. Preliminary data on ribosomal subunits indicated the feasibility -of many parts -of the project In that case the difference of large angle and small angle scattering gave a significant signal when averaged -over 1,000 aligned particle images, whereas the TMV (tobacco mosaic virus) control subtracted to background. This may be indicative of the RNA distribution in the subunits, but the arguments are indirect The elemental map should be much more straightforward to interpret. A key unknown is the degree of localization possible with the 132 eV loss electrons. This is -estimated to be better than'b.5 nra, but needs to be tested. Control specimens will be TMV and filamentous viruses which are ideal for alignment and have known or strongly predicted phosphorus distributions. Once the protocols for data collection are established and control spectra match theory, phosphorus mapping will be attempted on 30S and 50S ribosomal subunits. In addition to distinguishing nucleic, acid from protein, this technique should be useful for ing phosphorylated proteins and phospholipids. The same technique can be applied to elemental mapping of B, C, N, 0, F; Fe, Mg, Ca and other elements in our specimens using the appropriate energy loss and control signals.

磷L2，132 EV的Edge非常弱，但 提供特定于元素的信号。 磷的直接成像 使用损失这种能量的电子需要 剂量比已知损害分子的剂量高得多。 多低 使用同时记录的茎中可以在茎中进行剂量成像 暗场环形检测器信号定位图像的颗粒 平均。 总结数千个弱磷信号 对齐的颗粒应足以获得 本质上是未损坏的分子。 核糖体的初步数据 亚基表示该项目的可行性 - 许多部分 那种情况是大角度和小角度散射的差异 平均时给出明显的信号 1,000个对齐的粒子图像，而TMV（烟草病毒） 控制减去背景。 这可能表明RNA 亚基中的分布，但论点是间接的 元素地图应该更加直接地解释。 钥匙 未知的是132 eV损失可能的定位程度 电子。 估计比'B.5 NRA更好，但需要 进行测试。 控制标本将是TMV和丝状病毒 这是对齐的理想选择，并且已经知道或强烈预测 磷分布。 一旦数据收集协议是 建立和控制光谱匹配理论，磷映射将 尝试在30s和50s的核糖体亚基上尝试。 此外 区分核酸，酸和蛋白质，该技术应为 可用于磷酸化蛋白质和磷脂。 相同 技术可以应用于B，C，N，0，F的元素映射； fe 使用适当的标本中的MG，CA和其他元素 能源损失和控制信号。